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Smoke contains a mixture of harmful gases, chemicals, and superheated particles. Inhalation of smoke causes generalized hypoxia and airway inflammation due to impaired oxygen transport and utilization, as well as thermal and chemical injury in the airways. Generally, treatment is supportive with oxygen therapy and airway management, including chest physiotherapy, bronchodilators, and nebulization. Immediate oxygen therapy is mandatory for all suspected smoke inhalation patients and should not be delayed pending diagnostic test results or due to "normal" oxygen saturation readings that can be falsely elevated in carbon monoxide intoxication. Smoke inhalation patients with mild clinical signs who respond well to initial stabilization generally have a favorable prognosis. However, patients with severe signs or progression despite initial stabilization may require more advanced or intensive care., (© 2024 by American Animal Hospital Association.)

Case Series Summary: This case series describes seven cats that were treated with high-flow nasal cannula oxygen therapy (HFNOT). Seven cats were prospectively (n = 5) or retrospectively (n = 2) included from three veterinary university referral centers between March 2020 and September 2023. Data on signalment, medical history, clinical and diagnostic findings, treatment administered, response to HFNOT and outcomes were recorded. All cats included in this case series failed to respond to oxygen cage or flow-by oxygen therapy and were subsequently transitioned to HFNOT. After this transition, these cats demonstrated a marked improvement in respiratory parameters, including respiratory rate, effort and oxygen saturation measured by pulse oximetry, within 1 h of initiating HFNOT. All cats tolerated HFNOT well without any complications., Relevance and Novel Information: There is limited literature reporting the use of HFNOT in feline patients. This is the first case series in the literature of HFNOT utilized as an advanced oxygen delivery method for feline respiratory failure. This case series indicates that HFNOT improves oxygenation in feline patients that fail to respond to conventional oxygen therapy., Competing Interests: Conflict of interestThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objective: To evaluate the respiratory rate-oxygenation index (ROX), modified ROX index (ROX-HR), and the ratio of pulse oximetry saturation (Spo 2 ) to Fio 2 (SF) to determine if these indices over time are predictive of outcome in dogs treated with high-flow nasal cannula oxygen therapy (HFNC)., Design: Retrospective study., Setting: Two university teaching hospitals., Animals: Eighty-one client-owned dogs treated with HFNC for hypoxemic respiratory failure., Interventions: None., Measurements and Main Results: The ROX was defined as the SF divided by the respiratory rate (RR), and the ROX-HR was defined as the ROX divided by the heart rate multiplied by 100. The overall success rate of HFNC was 44% (n = 36/81). Dogs weaned from HFNC had a significantly higher ROX (P < 0.0001) at 1-3, 5-10, 12, and 15 hours than dogs that failed HFNC. Both the ROX and SF showed excellent discriminatory power in predicting HFNC failure at 6 hours, with an area under receiver operating curve of 0.85 (95% confidence interval: 0.72-0.99; P < 0.002) and 0.86 (95% confidence interval: 0.73-0.99; P < 0.001), respectively. The optimal cutoff values for predicting HFNC failure at 6 hours were a ROX ≤3.68 (sensitivity 72%, specificity 92%) and an SF ≤143 (sensitivity 79%, specificity 93%)., Conclusions: These results suggest that similar to people, the ROX and SF are useful predictors of HFNC failure. These indices are easy to measure at the bedside and may have clinical use. Future prospective studies are warranted to confirm the findings and to optimize cutoff values in a larger population of dogs undergoing HFNC., (© Veterinary Emergency and Critical Care Society 2024.)

Introduction: This study observed the effects of oxygen supplementation, via an oxygen concentrator, on peripheral arterial blood oxygenation (SpO2) measured by pulse oximetry in anaesthetised cats undergoing spay in three different surgical positions. A total of 192 female feral cats were investigated for a large-scale trap-neuter-release program. Cats were anaesthetised with an intramuscular combination of butorphanol (0,4 mg / kg), ketamine (7-10 mg / kg) and medetomidine (0,03-0,05 mg / kg). Cats were randomly allocated to undergo spay in either Trendelenburg (TR) (70° downward head tilt), lateral (LR) or dorsal (DR) recumbency. Cats were breathing spontaneously either room air or 2 L/minute oxygen via a tight-fitting face mask. Pulse rate (in beats per minute), respiratory rate (in breaths per minute) and SpO2 (in percentage) were measured at baseline in left lateral recumbency and afterwards continuously after being positioned in allocated surgical position. At the end of surgery, cats were placed again in left recumbency, and all parameters were re-evaluated after five minutes. Overall, 33 % of cats showed severe arterial oxygen desaturation (SpO2 < 90 %) at baseline when breathing room air. When oxygen was supplemented during the procedure, arterial oxygen desaturation resolved in all cats. At the end of the procedure, 29 % of cats were hypoxaemic when oxygen was not supplemented, with an overall higher percentage of hypoxaemic cats in TR as compared to DR and LR recumbencies. All cats recovered well from surgery and were released within 24 hours post-anaesthesia. Arterial oxygen desaturation is frequent in cats anaesthetised with injectable anaesthesia for spay under field conditions. Oxygen supplementation administered via a tight-fitting mask resolved arterial oxygen desaturation in this feral cat population regardless of the surgical position and therefore oxygen supplementation is recommended in any case.

Background: High-flow nasal oxygen (HFNO) therapy is a non-invasive respiratory support method that provides oxygen-enriched, warmed, and humidified air to respiratory-compromised patients. It is widely used in human medical care, but in veterinary medicine it is still a relatively new method. No practical guidelines exist for its use in canine pneumonia patients, although they could potentially benefit from HFNO therapy. This study aims to provide a new, safe, non-invasive, and effective treatment protocol for oxygen supplementation of non-sedated dogs with pneumonia., Methods: Twenty privately owned dogs with pneumonia will receive HFNO therapy at a flow rate of 1-2 L/kg, and the fraction of inspired oxygen will be determined individually (ranging from 21% to 100%). HFNO therapy will continue as long as oxygen support is needed based on clinical evaluation. Patients will be assessed thrice daily during their hospitalisation, with measured primary outcomes including partial pressure of oxygen, oxygen saturation, respiratory rate and type, days in hospital, and survival to discharge., Discussion: The proposed protocol aims to provide a practical guideline for applying HFNO to dogs hospitalised due to pneumonia. The protocol could enable more efficient and well-tolerated oxygenation than traditional methods, thus hastening recovery and improving survival of pneumonia patients., (© 2023. BioMed Central Ltd., part of Springer Nature.)

This study evaluated the effects of various flow rates and fractions of oxygen on arterial blood gas parameters and on the fraction of inspired oxygen (F I O 2 ) delivered to the distal trachea. Oxygen was administered to 6 healthy, conscious, standing, adult horses via single nasal cannula positioned within the nasopharynx. Three flow rates (5, 15, 30 L/min) and fractions of oxygen (21, 50, 100%) were delivered for 15 minutes, each in a randomized order. F I O 2 was measured at the level of the nares and distal trachea. Adverse reactions were not observed with any flow rate. F I O 2 (nares and trachea) and PaO 2 increased with increasing flow rate and fraction of oxygen (P < .0001). F I O 2 (trachea) was significantly less than F I O 2 (nares) at 50% and 100% oxygen at all flow rates (P < .0001). Differences in PaO 2 were not observed between 100% oxygen-5L/min and 50% oxygen-15L/min and or between 100% oxygen-15L/min and 50% oxygen-30L/min. Tracheal F I O 2 for 100% oxygen-15L/min was increased compared to 50% oxygen-30L/min (P < .0001). Respiratory rate, ETCO 2 , PaCO 2 , and pH did not differ between treatments. Administration of 50% oxygen via nasal cannula at 15 and 30 L/min effectively increased in PaO 2 and was well tolerated in conscious, standing, healthy horses. While these results can be used guide therapy in hypoxemic horses, evaluation of the administration of 50% oxygen to horses with respiratory disease is warranted., (Copyright © 2023 Elsevier Inc. All rights reserved.)

A combination of tiletamine-zolazepam, medetomidine, and azaperone was used to immobilize captive Chacoan peccaries (Catagonus wagneri) for health assessments and biological sample collection at the Centro Chaqueño para la Conservación e Investigación (CCCI) in the Paraguayan Chaco during July in 2017 and 2018. In total, 83 peccaries kept in 0.25-1.50 hectare enclosures were immobilized via dart-administered anesthetic. Mean animal weight was 33.89±3.74 kg (standard deviation; n=77). The mean intramuscular (IM) anesthetic drug and dosages were 0.03±0.00 mg/kg of medetomidine, 0.91±0.10 mg/kg of Zoletil 50 (tiletamine-zolazepam), and 0.30±0.03 mg/kg azaperone. The mean time to recumbency after darting was 6.07±2.65 min. The mean time to reach the anesthetic plane postdarting was 10.00±2.00 min. Muscle relaxation was adequate to allow minor veterinary procedures. A mean dosage of 0.15±0.02 mg/kg of atipamezole was given IM to reverse the medetomidine. Recoveries were smooth and animals were standing by 59.17±30.18 min postreversal. Full recovery and release back to enclosures occurred 90±30 min postreversal. A single dose of this drug combination provided adequate anesthesia for 88% of adult Chacoan peccaries; 12% needed a supplemental dose of tiletamine-zolazepam because of failure to receive the full dose from the anesthetic dart. Sex and age did not impact the dosage required to achieve immobilization. Confinement during recovery from anesthesia is required with this protocol. Aside from mild hypoxemia, no adverse effects from anesthesia were observed. However, oxygen supplementation as a part of this protocol is recommended to support circulatory and respiratory capacity., (© Wildlife Disease Association 2023.)

Objective: A prospective clinical trial was performed to evaluate the efficacy and tolerance of high-flow nasal cannula (HFNC) in dogs with hypoxemia., Animals: 20 client-owned dogs failing conventional oxygen therapy (COT)., Procedures: Patients admitted to the ICU for treatment of hypoxemic respiratory failure were enrolled in the study. PaO2, SPO2, respiratory rate (RR), and acute patient physiologic and laboratory evaluation scores were obtained at the time of COT failure and after initiation of HFNC. Complications and patient tolerance while receiving HFNC were also recorded., Results: Compared to COT, the median PaO2 and SO2 were significantly higher when dogs were receiving HFNC (60.8 vs 135.6 mm Hg and 90.7% vs 99.25%, respectively). Dogs receiving HFNC had a significant reduction in median RR as compared to dogs undergoing COT (52 vs 36 breaths per minute). After the initiation of HFNC, all dogs showed clinical improvement as measured by PaO2, SO2, and RR. Of 20 dogs, 6 ultimately failed HFNC and mechanical ventilation was recommended. Nine dogs undergoing HFNC survived to discharge, and acute patient physiologic and laboratory evaluation scores had a significant positive severity correlation with death. Complications included pneumothorax in 1 dog., Clinical Relevance: COT has limited flow rates due to airway irritation caused by room temperature, nonhumidified oxygen. HFNC uses vapor humidification and heated oxygen, allowing for higher flow rates. In people, HFNC is used as escalation of oxygen therapy when COT fails. Dogs treated with HFNC had significant improvements in PaO2, SO2, and RR as compared to COT. HFNC is well tolerated and effective in treating hypoxemia in dogs.

Background: Respiratory disease is common in critically ill neonatal foals. Traditional oxygen therapy (TOT) with nasal insufflation of oxygen is often used to provide first-line respiratory support. Mechanical ventilation is used in foals which require a greater level of support but requires specialist expertise and can be associated with significant complications. Non-invasive ventilation (NIV) enables a greater level of respiratory support without the need for intubation. High flow oxygen therapy (HFOT) is a mode of NIV commonly used in human intensive care., Objectives: To describe the use of HFOT in hospitalised neonatal foals., Study Design: Retrospective case series., Methods: Hospital records of neonatal foals admitted between 2018 and 2019 that received treatment with HFOT were reviewed. Clinical data and complications were recorded., Results: Fourteen foals were identified and the median duration of use was 43 hours (range 2-93 hours) with a median flow rate of 0.7L/kg/min (range 0.42-1.67). Ten foals survived to discharge. No significant complications associated with the technique were recorded., Main Limitations: A small study population which was retrospectively reviewed., Conclusions: This study provides preliminary information about the clinical use of HFOT in neonatal foals. The technique was well tolerated and no significant adverse effects were noted. However, further study is required to evaluate efficacy., (© 2021 EVJ Ltd.)

Objective: To describe the clinical characteristics and outcomes in a population of dogs with negative-pressure pulmonary edema (NPPE) and to identify the main causes of the disease. To evaluate any associations with morbidity and mortality., Design: Retrospective study., Setting: Three university teaching hospitals and 2 private referral centers in the United Kingdom., Animals: Thirty-five client-owned dogs presented with NPPE., Interventions: None MEASUREMENTS AND MAIN RESULTS: Data collected included patient characteristics, clinical history, clinicopathological abnormalities, radiographic features, treatments, and outcomes. The median age was 4 months (range 2-90) and median weight was 7.1 kg (range 1.7-37.2). There were many causes of NPPE including leash tugs, near hanging, accidental choking, anatomical obstruction to airflow, and purposeful airway obstruction by people. The most common cause of NPPE was accidental choking (40% of cases). Dogs with an anatomical obstruction were older than 24 months. Hypoxemia with an increased alveolar-arterial gradient was common on presentation. The majority of thoracic radiographs (65.7%) showed an alveolar or interstitial pattern in the caudodorsal area as previously described in the literature. Oxygen therapy was administered to 33 (94.3%) dogs. Furosemide was administered to 18 (51.4%) dogs. The median length of hospitalization was 2 days (range 0-14). Twenty-eight (80%) dogs survived to discharge. Seven dogs were mechanically ventilated and only 2 of them (28.6%) survived to discharge. The requirement for mechanical ventilation was the only parameter associated with mortality (P < 0.001)., Conclusions: Most cases of NPPE occur in juvenile dogs. Different incidents associated with upper airway obstruction can produce an episode of NPPE. Choking on food or toys and near hanging have not been previously described in the veterinary literature as inciting causes of NPPE. The overall prognosis is good., (© Veterinary Emergency and Critical Care Society 2021.)

High-flow nasal oxygen therapy (HFNT) and positive pressure ventilation (PPV) are interventions used in the management of animals with respiratory failure. The indications for the use of these modalities, clinical application, prognosis, and a review of the current veterinary evidence are provided., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Respiratory distress is a common ailment in small animal medicine. Oxygen supplementation is a mainstay of initial therapy. High Flow Nasal Cannula Oxygen Therapy (HFNCOT) has become increasingly popular as a treatment modality in human medicine, and more recently in canine patients. These devices deliver high flow rates of heated and humidified oxygen at an adjustable fraction of inspired oxygen . This article reviews current literature in human patients on HFNCOT as well as studies that have evaluated its use in veterinary patients. A discussion of the respiratory physiology that is associated with respiratory distress, in addition to an overview of currently available oxygen supplementation modalities is provided. The physiologic benefits of HFNCOT are explained, as are technical aspects associated with its use. Recommendations on initial settings, maintenance therapy, and weaning are also described., (Published by Elsevier Inc.)

Dogs with lower airway pathology that present in respiratory distress often receive oxygen therapy as the first line of treatment regardless of the underlying cause. Conventional "low-flow" systems deliver oxygen with a maximum flow rate of 15 L/minute. Traditionally, when an animal's respiratory status does not improve with conventional oxygen therapy and treatments for underlying disease, options might be limited to either intubation and mechanical ventilation or humane euthanasia. High-flow oxygen therapy (HFOT) has been gaining popularity in veterinary medicine as an alternative route of oxygen supplementation for animals that require support beyond conventional therapy. High-flow oxygen therapy can supply a mixture of air and oxygen via a heated and humidified circuit. It is user friendly and can be used in an environment in which mechanical ventilation is unavailable. This review article is written for emergency doctors and general practitioners who lack access to mechanical ventilation. This article briefly reviews pertinent respiratory physiology, traditional oxygen supplementation techniques, the physiology of HFOT, and the limited evidence available in veterinary medicine regarding the use of HFOT, its applications, and limitations. Guidelines for the use of HFOT are suggested and HFOT is compared to conventional therapy., (Copyright and/or publishing rights held by the Canadian Veterinary Medical Association.)

1. Pulmonary hypertension, associated with mitochondrial function in the lung tissue of broilers, can occur at hypoxic high altitudes. The present research examined the impacts of O 2 supplementation at different embryonic stages on broiler organ development and antioxidant enzyme activities.2. In total, 360 eggs from Ross 308 broiler breeders at sea level were divided into a control group (O 2 non-supplementation group) and three experimental groups daily 1 h 23.5% O 2 supplementation from days 0 to 11 (O 0-11 ), from days 12 to 21 (O 12-21 ), and from days 18 to 21 (O 18-21 ) of embryonic age.3. The lung, heart, right ventricular (RV), and left ventricular (LV) + septum of newly hatched and seven day old chicks from every group were dissected and weighed. Antioxidant enzyme activities were examined in their lung tissue.4. The lung weight did not change in any group. At hatching, the heart weight (g and %) was higher in the O 12-21 and O 18-21 groups than in the O 0-11 and control groups, but the relative heart weight was the highest in the O 18-21 group in comparison with the O 12-21 group.5. Superoxide dismutase (SOD) activity increased in all experimental groups at both ages, but glutathione peroxidase (GPx) activity increased only in seven day old chicks. Catalase (CAT) exhibited high activity in the O 12-21 and O 18-21 groups at hatching. In the seven day old chicks, while the CAT activity did not change in the O 18-21 group, it decreased in the O 0-11 group and increased in the O 12-21 group.6. Glutathione reductase (GR) activity did not change in the O 18-21 group, but GR exhibited low activity in the O 0-11 group and high activity in the O 18-21 group in newly hatched chicks. The GR activity only decreased in the O 18-21 group of seven day old chicks.7. The results indicated that oxygen supplementation to the incubator caused alterations in the antioxidant enzyme activities in the lungs of broiler chicks, and this may have been in response to oxidative stress.

Objective: To compare oxygenation and ventilation in white-tailed deer (Odocoileus virginianus) anesthetized with two treatments with and without oxygen supplementation., Study Design: Randomized, blinded, crossover study., Animals: A total of eight healthy adult white-tailed deer weighing 49-62 kg., Methods: Each deer was anesthetized twice intramuscularly: 1) treatment XK, xylazine (2 mg kg -1 ) and ketamine (6 mg kg -1 ) and 2) treatment XTZ, xylazine (2 mg kg -1 ) and tiletamine-zolazepam (4 mg kg -1 ). With the deer in sternal position, arterial and venous blood was collected before and at 30 minutes during administration of oxygen at 1 L minute -1 through a face mask. PaO 2 and heart rate (HR) were compared using two-way repeated measures anova. pH, PaCO 2 and lactate concentration were analyzed using mixed-effects linear models, p < 0.05., Results: When breathing air, PaO 2 was < 80 mmHg (10.7 kPa) in six and seven deer with XK and XTZ, respectively, and of these, PaO 2 was < 60 mmHg (8.0 kPa) in three and five deer, respectively. With oxygen supplementation, PaO 2 increased to 128 ± 4 and 140 ± 5 mmHg (17.1 ± 0.5 and 18.7 ± 0.7 kPa), mean ± standard error, with XK and XTZ, respectively (p < 0.001). PaO 2 was not significantly different between treatments at either time point. HR decreased during oxygen supplementation in both treatments (p < 0.001). Lactate was significantly lower (p = 0.047) with XTZ than with XK (2.2 ± 0.6 versus 3.5 ± 0.6 mmol L -1 ) and decreased (p < 0.001) with oxygen supplementation (4.1 ± 0.6 versus 1.6 ± 0.6 mmol L -1 ). PaCO 2 increased in XTZ during oxygen breathing., Conclusions and Clinical Relevance: Treatments XK and XTZ resulted in hypoxemia, which responded to oxygen supplementation. Both treatments are suitable for immobilization of white-tailed deer under the study circumstances., (Copyright © 2021 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.)

Objectives: To prospectively describe the impact of gas flow rate and temperature on dog's tolerance of high-flow nasal oxygen therapy during recovery from anaesthesia, hypothesizing that higher flow rates and temperatures will decrease tolerance., Materials and Methods: Twelve non-dyspnoeic client-owned dogs recovering from general anaesthesia were included in this study. After extubation, a nasal cannula was positioned and high-flow nasal oxygen therapy was initiated. Two flow rates (two or four time the theoretical minute ventilation: HF2 and HF4), each of them combined with two temperatures (31 and 37°C: T31 and T37), were randomly applied (four conditions per dog). For each condition, cardiovascular and respiratory parameters (heart rate, respiratory rate, systolic arterial blood pressure and pulse oximeter oxygen saturation), sedation score and tolerance score were recorded at initiation (T 0 ) and after 10 minutes of accommodation (T 10 )., Results: Sedation scores were not significantly different between the four conditions. Cardiovascular and respiratory parameters were not significantly different between any condition at both T 0 and T 10 . Tolerance scores were good and not significantly different between any flow rate or temperature (HF2-T31: 4 (2-4), HF4-T31: 4 (2-4), HF2-T37: 4 (2-4), HF4-T37: 4 (1-4))., Clinical Significance: The gas flow rates and temperatures studied have no impact on tolerance during the recovery period of non-dyspnoeic dogs, and high-flow nasal cannula is well tolerated. Further studies are required to confirm these results in dyspnoeic dogs., (© 2020 British Small Animal Veterinary Association.)

Respiratory distress is commonly seen in dogs and cats presenting to the emergency room. Rapid identification of respiratory difficulty with strategic stabilization and diagnostic efforts are warranted to maximize patient outcome. This article focuses on the relevant anatomy and physiology of the respiratory system and the clinical recognition, stabilization, and initial diagnostic planning for small animal patients that present for respiratory emergencies., Competing Interests: Disclosure The authors have nothing to disclose., (Published by Elsevier Inc.)

Aims: To evaluate the effect of a novel method of practical oxygen therapy on physiological parameters related to survival, weaning weight and preweaning mortality of neonatal piglets under commercial farm conditions. Methods: Piglets from hyperprolific sows born with signs of asphyxia, (n = 109; <6 on a score of respiration, meconium staining and activity) or very low birth weight (VLBW; n = 112; <1.05 kg) were selected for the study. Approximately half of each group (n = 55 VLBW piglets and n = 57 piglets with asphyxia) received 100% oxygen immediately after birth using a specially designed facemask for 45 seconds (VLBW) or 1 minute (asphyxiated). Physiological parameters (peripheral blood oxygen saturation (SpO 2 ) blood glucose concentration and rectal temperature) were measured before oxygen treatment 5 minutes after birth (SpO 2 ) and 24 hours later (SpO 2 , blood glucose concentration, temperature). Weight at birth, at 24 hours and at 21 days of age, preweaning mortality, and estimated colostrum intake were also recorded. Results: A significant treatment effect on SpO 2 was observed (p = 0.013 and p < 0.001 for VLBW and asphyxiated piglets respectively). VLBW and asphyxiated piglets that received oxygen treatment had higher SpO 2 after treatment (measured 5 minutes after birth, 97.7 and 97.8% respectively) compared to immediately after birth (93.3 and 86.8% respectively) while untreated piglets showed no variation. Blood glucose concentrations increased in all piglets between birth and 24 hours of age (p = 0.003 and p < 0.001 for asphyxiated and VLBW piglets respectively) and this was higher in asphyxiated piglets that received oxygen than those that did not (5.6 (SE 0.2) mmol/L; p < 0.05). Estimated colostrum intake was higher in asphyxiated (401.6 (SD 24.4) g/kg) and VLBW (374.9 (SE 23.4 g/kg) piglets that received oxygen than those that did not (273.2 (SE 24.1) g/kg; p < 0.001 and 249.0 (SE 22.5) g/kg; p < 0.001 respectively). Similarly weight at weaning was higher in asphyxiated (5.8 (SE 0.2) kg) and VLBW (4.9 (SE 0.2) kg) piglets that received oxygen therapy than control animals (4.9 (SE 0.2) kg; = 0.005 and 4.1 (SE 0.2) kg; p = 0.008 respectively). Furthermore, oxygen treatment markedly reduced preweaning mortality from 9/52 (17%) untreated to 1/57 (1.7%) oxygen-treated piglets suffering asphyxia at birth (p = 0.006). Conclusions: Oxygen therapy improves physiological and productive parameters in piglets born with signs of asphyxia or VLBW. The incorporation of this strategy as part of the farrowing routine enhances the advantages of rearing hyperprolific sows.

Background: Brachycephalic airway syndrome can pose a risk of complicated recovery from anesthesia as a result of irritation to the excess pharyngeal andlaryngeal tissue present in affected dogs. High-flow nasal cannula (HFNC) oxygen therapy is a respiratory support modality that offers provision of continuous positive airway pressure via high gas flow rates. The HFNC system actively warms and humidifies inspired gases, which improves comfort and facilitates tolerance of the high flow rates in people and dogs. HFNC oxygen therapy was applied to brachycephalic dogs that developed increased work of breathing or hypoxemia in the recovery phase of anesthesia to determine if this device would be tolerable and effective for relief of upper respiratory difficulty., Key Findings: The HFNC nasal prong interface is well suited to the brachycephalic facial structure. The application of HFNC was found to reduce dyspnea scores in patients with signs of upper airway obstruction after general anesthesia. Aerophagia and changes in PCO 2 were noted., Significance: Application of HFNC in the recovery period may result in improved airflow during times of somnolent obstructive breathing, not unlike the use of continuous positive airway pressure therapy in sleep-disordered breathing in people., (© Veterinary Emergency and Critical Care Society 2020.)

Objective: To determine the effect of high-flow nasal cannula (HFNC) oxygen therapy on cardiorespiratory variables and outcome in dogs with acute hypoxemic respiratory failure., Design: Prospective, sequential clinical trial., Setting: University veterinary teaching hospital., Animals: Twenty-two client-owned dogs that failed to respond to traditional oxygen support., Interventions: Initiation of HFNC therapy after traditional oxygen supplementation failed to increase Spo 2 > 96% and Pao 2 > 75 mm Hg or improve respiratory rate/effort., Measurements and Main Results: Physiological variables, blood gas analyses, and dyspnea/sedation/tolerance scores were collected prior to HFNC initiation (on traditional oxygen support [time 0 or T0]), and subsequently during HFNC oxygen administration at time 30 minutes, 60 minutes, and 7 ± 1 hours. Relative to T0, use of HFNC resulted in a decreased respiratory rate at 1 hour (P = 0.022) and 7 hours (P = 0.012), a decrease in dyspnea score at all times (P < 0.01), and an increase in Spo 2 at all times (P < 0.01). There was no difference in arterial/venous Pco 2 relative to T0, although Paco 2 was correlated with flow rate. Based on respiratory assessment, 60% of dogs responded to HFNC use by 30 minutes, and 45% ultimately responded to HFNC use and survived. No clinical air-leak syndromes were observed., Conclusions: HFNC use improved oxygenation and work of breathing relative to traditional oxygen therapies, without impairing ventilation. HFNC use appears to be a beneficial oxygen support modality to bridge the gap between standard oxygen supplementation and mechanical ventilation., (© Veterinary Emergency and Critical Care Society 2020.)

Objective: To evaluate arterial oxygenation during the first 4 postoperative hours in dogs administered different fractions of inspired oxygen (FiO 2 ) during general anesthesia with mechanical ventilation., Study Design: Prospective, randomized clinical trial., Animals: A total of 20 healthy female dogs, weighing >15 kg and body condition scores 3-7/9, admitted for ovariohysterectomy., Methods: Dogs were randomized to breathe an FiO 2 >0.9 or 0.4 during isoflurane anesthesia with intermittent positive pressure ventilation. The intraoperative PaO 2 :FiO 2 ratio was recorded during closure of the linea alba. Arterial blood was obtained 5, 60 and 240 minutes after extubation for measurement of PaO 2 and PaCO 2 (FiO 2  = 0.21). Demographic characteristics, duration of anesthesia, PaO 2 :FiO 2 ratio and anesthetic agents were compared between groups with Wilcoxon tests. The postoperative PaO 2 , PaCO 2 , rectal temperature, a visual sedation score and events of hypoxemia (PaO 2 < 80 mmHg) were compared between groups with mixed-effects models or generalized linear mixed models., Results: Groups were indistinguishable by demographic characteristics, duration of anesthesia, anesthetic agents administered and intraoperative PaO 2 :FiO 2 ratio (all p > 0.08). Postoperative PaO 2 , PaCO 2 , rectal temperature or sedation score were not different between groups (all p > 0.07). During the first 4 postoperative hours, hypoxemia occurred in three and seven dogs that breathed FiO 2 >0.9 or 0.4 during anesthesia, respectively (p = 0.04)., Conclusions and Clinical Relevance: The results identified no advantage to decreasing FiO 2 to 0.4 during anesthesia with mechanical ventilation with respect to postoperative oxygenation. Moreover, the incidence of hypoxemia in the first 4 hours after anesthesia was higher in these dogs than in dogs breathing FiO 2 >0.9., (Copyright © 2020 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.)

Objective: To investigate the effects of a heat and moisture exchanger (HME) on the temperature and humidity of inhaled gas in isoflurane-anesthetized dogs., Study Design: Prospective, interventional study., Animals: A total of four experimental dogs and four client-owned dogs weighing 13.9 ± 7.4 kg (mean ± standard deviation)., Methods: The four experimental dogs were anesthetized on two occasions with and without an intact HME at least 1 week apart. The four client-owned dogs were anesthetized once only for a surgical procedure and assigned to the HME group or no-HME group in alternate order, resulting in six dogs for each group. All dogs were premedicated, anesthetized with propofol and intubated. The HME was connected to the endotracheal tube. Anesthesia was maintained with isoflurane. A digital thermo-hygrometer was placed between the endotracheal tube and HME. The temperature and relative humidity of the inhaled gas were measured every 5 minutes for 60 minutes and the absolute humidity was calculated at each time point., Results: The temperature and absolute humidity of the inhaled gas was significantly higher at 5-60 minutes after intubation in the HME group than in the no-HME group. Absolute humidity was maintained above 29 mg H 2 O L -1 in the HME group. No significant time-dependent effects on temperature, relative humidity or absolute humidity of the inhaled gas were observed., Conclusions and Clinical Relevance: The temperature and absolute humidity of the inhaled gas were higher when an HME was used during isoflurane anesthesia in dogs. The use of an HME may reduce the risk of dehydration and dysfunction of the airway mucosal epithelium., (Copyright © 2020 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.)

In this review, we summarize the results of studies that investigated the effects of hypoxia and reoxygenation in cardiac arrest, including the use of different fractions of inspired oxygen, in neonatal animals. The studies were heterogenous in terms of anaesthetic regimens, and definitions of cardiac arrest and circulatory recovery. Cardiopulmonary resuscitation with 100% oxygen increased oxidative stress in maturing rats. Studies in fetal/neonatal lambs and post-transitional neonatal piglets indicate no consistent differences between ventilation with 21% vs. 100% oxygen with regards to recovery times, oxygen damage or adverse events. If 21% oxygen is as effective as 100% oxygen in newborn infants with cardiac arrest requiring chest compression, the use of 21% instead of 100% oxygen could reduce morbidity and mortality in asphyxiated infants. Unanswered questions include what is the most optimal cerebral oxygen delivery during reperfusion, as well as oxygenation targets after return of spontaneous circulation., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (© 2020 Elsevier Ltd. All rights reserved.)

Objectives: To describe the use, effectiveness and tolerance of high-flow oxygen therapy in dyspnoeic dogs., Materials and Methods: Prospectively, dogs in acute respiratory distress admitted to an intensive care unit between January and May 2018 that failed to respond to nasal oxygen therapy and medical stabilisation after 30 minutes were transitioned to high-flow oxygen therapy. High-flow oxygen therapy, delivered an inspired oxygen fraction of 100% using an air/oxygen blender, active humidifier, single warmed tube and specific nasal cannula. Respiratory rate, pulse oximetry (SpO 2 ), heart rate and a tolerance score were assessed every 15 minutes from T 0 (under nasal oxygen) to 1 hour (T 60 ), and PaO 2 and PaCO 2 at T 0 and T 60 . Complications were recorded for each dog., Results: Eleven dogs were included. At T 60 , PaO 2 , flow rate and SpO 2 were significantly greater than at T 0 (171 ± 123 versus 73 ± 24 mmHg; P=0.015; 18 ±12 L/minute versus 3.2 ± 2.0 L/minute, P<0.01; 97.7 ±2.3% versus 91.6 ±7.2%, P=0.03, respectively). There was no significant difference in PaCO 2 , respiratory rate or heart rate between T 0 and T 60 . Tolerance was excellent, and there were no complications., Clinical Significance: High-flow oxygen therapy improves markers of oxygenation in dyspnoeic dogs and is an effective means to deliver oxygen with comfort and minimal complications., (© 2019 British Small Animal Veterinary Association.)

Objective: The aim of this study was to evaluate the consequences of different oxygen supplementation methods on arterial blood gas analysis during an injectable anesthesia., Material and Methods: A total of 29 rabbits with dental diseases (tooth elongation) were sampled before, during and after coronal reduction. Oxygen was provided either via the flow-by method or with a nasal oxygen tube; the control group breathed room air., Results: All patients receiving oxygen developed respiratory acidosis that intensified during the course of anesthesia. Furthermore, these groups experienced reduced respiratory rates intraoperatively, nevertheless they showed elevated oxygen parameters (hyperoxemia) in the arterial blood gas analysis. No significant differences could be demonstrated between the 2 oxygen providing methods. In the control group, pH remained stable, the oxygen parameters however decreased to less than 80 mmHg (hypoxemia)., Conclusions: Although there were no clinical consequences of hypoxemia or hyperoxemia, moderate oxygen support during an injectable anesthesia is recommended due to the development of hypoxemia. A balance between oxygen supply and oversupply needs to be established to aid in avoiding oxygen toxicity., Competing Interests: Die Autoren bestätigen, dass kein Interessenkonflikt besteht., (© Georg Thieme Verlag KG Stuttgart · New York.)

Objective: To determine the feasibility, degree of respiratory support, and safety of high flow nasal cannula (HFNC) oxygen therapy in sedated and awake healthy dogs, when compared to traditional nasal cannula (TNC) oxygen administration., Design: Randomized experimental crossover study., Setting: University research facility., Animals: Eight healthy dogs., Interventions: Variable flow rates (L/kg/min) were assessed, TNC: 0.1, 0.2, and 0.4 and HFNC: 0.4, 1.0, 2.0, and 2.5. HFNC was assessed in sedated and awake dogs., Measurements: Variables measured included: inspiratory/expiratory airway pressures, fraction of inspired oxygen (FiO 2 ), end-tidal oxygen (ETO 2 ), end-tidal carbon dioxide (ETCO 2 ), partial pressure of oxygen (PaO 2 ), partial pressure of carbon dioxide (PaCO 2 ), temperature, heart/respiratory rate, arterial blood pressure, and pulse oximetry. Sedation status, complications, and predefined tolerance and respiratory scores were recorded., Main Results: Using HFNC, continuous positive airway pressure (CPAP) was achieved at 1 and 2 L/kg/min. CPAP was not higher at 2.5 than 2 L/kg/min, with worse tolerance scores. Expiratory airway pressures were increased when sedated (P = 0.006). FiO 2 at 0.4 L/kg/min for both methods was 72%. FiO 2 with TNC 0.1 L/kg/min was 27% and not different from room air. The FiO 2 at all HFNC flow rates ≥1 L/kg/min was 95%. PaO 2 for HFNC 0.4 L/kg/min was lower than at other flow rates (P = 0.005). The only noted complication was aerophagia. PaCO 2 was increased with sedation and use of HFNC when compared to baseline (P = 0.006; P < 0.01)., Conclusions: Use of HFNC in dogs is feasible and safe, provides predictable oxygen support and provides CPAP, but may cause a mild increase in PaCO 2 . Flow rates of 1-2 L/kg/min are recommended. If using TNC, flow rates above 0.1 L/kg/min may attain higher FiO 2 ., (© Veterinary Emergency and Critical Care Society 2019.)

AIMS To compare the effect of oxygen supplementation using flow-by or a face mask on the partial pressure of arterial oxygen (PaO 2 ) in sedated dogs. METHODS Twenty healthy dogs weighing >15 kg, of mixed sex and breed, were enrolled in a randomised cross-over study. Each dog was sedated with I/M 0.015 mg/kg medetomidine and 0.5 mg/kg methadone. Twenty minutes later dogs were exposed to two 5-minute treatment periods of oxygen supplementation separated by a 15-minute washout period during which dogs were allowed to breathe room air. During the treatment periods, oxygen was delivered at a flow rate of 3 L/minute either through a face mask (face mask oxygenation), or via a tube held 2 cm from the dog's nares (flow-by oxygenation). The order in which the treatments were administered was randomised. Arterial blood was collected for blood gas analysis and rectal temperature measured at four times: prior to commencing treatments, after each treatment, and at the end of the 15 minutes washout period between treatments. RESULTS The mean PaO 2 in arterial samples taken from the dogs after face mask oxygen supplementation was 371.3 (SE 13.74) mmHg which was higher than in samples taken after they received flow-by oxygen supplementation (182.2 (SE 6.741) mmHg; p<0.001). The mean PaO 2 in samples taken after receiving either form of oxygen supplementation was higher than in samples taken after the dogs had been breathing room air (82.43 (SE 2.143) mmHg; p<0.001). There was no association between sex, age, weight or breed of dogs and blood gas parameters or rectal temperature (p>0.05). CONCLUSIONS Oxygen supplementation delivered using a face mask was more effective at increasing PaO 2 than flow-by oxygen supplementation. Flow-by oxygen supplementation at a distance of 2 cm from the nose may be a suitable alternative when the use of a face mask is not tolerated by the patient.

Objective: To determine the accuracy and precision of flowmeters used for oxygen therapy in a veterinary teaching hospital., Study Design: An observational study., Methods: A total of 50 flowmeters used for oxygen therapy were evaluated using Defender 530 gas flow analyzers to measure flow. For each flowmeter, a minimum of seven flow settings were tested in random order and in triplicate. Flow measured at ambient conditions was converted to standardized flow specifications (21.1 °C and 760 mmHg) and analyzed using general linear mixed models. Flowmeters were considered accurate at a given flow setting when the targeted mean flow was within the corresponding 95% confidence interval. Precision of flow was characterized based on the magnitude of variance component estimates., Results: Flowmeters of 1.0, 3.5 and 8.0 L minute -1 were considered accurate across flow settings corresponding to their capacity range. Flowmeters of 7.0 and 15.0 L minute -1 were accurate at flow settings ≤2.0 L minute -1 . For flow settings ≥3.0 L minute -1 , average oxygen flow was consistently below reference values. Precision varied with the capacity of the flowmeter, ranked by decreasing precision as 1.0 > 3.5 > 8.0 > 7.0 > 15.0 L minute -1 ., Conclusions and Clinical Relevance: A flowmeter of the smallest maximum capacity within the desired flow range is more appropriate for smaller patients where accurate, precise flow delivery is needed. Although 15.0 L minute -1 flowmeters were accurate at flow settings ≤2.0 L minute -1 , the graduated increments do not allow exact flow settings <0.5 L minute -1 . Flowmeters of 15 L minute -1 capacity should be useful for high-flow oxygen delivery for which accuracy and precision are not critical., (Published by Elsevier Ltd.)

Objective: To describe the effects of high flow oxygen therapy (HFOT) in canine patients failing traditional oxygen therapy (TOT)., Design: Retrospective study., Setting: Private referral practice., Animals: Six client-owned dogs with primary pulmonary hypoxemia., Interventions: None., Measurements and Main Results: High flow oxygen was delivered by high flow nasal prongs to dogs assessed clinically to be failing TOTs. HFOT was able to significantly improve PaO2 compared to TOT in severely hypoxemic dogs (median, 133.75 mm Hg; range, 109.2-304.8) versus median 61.85 mm Hg (range, 52.3-71.8; xsP = 0.0412). Flow rates were significantly higher with HFOT compared to TOT (median, 688 mL/kg/min; range, 523-1,667 mL/kg/min) versus median 122 mL/kg/min (range, 80-208; P = 0.0412). Complications included patient discomfort requiring light sedation in 1/6 dogs and persistence of a pneumothorax in 1 dog. Hypoxemia resolved in 4/6 dogs., Conclusion: These data suggest HFOT is a viable clinical intervention for dogs with moderate-to-severe hypoxemia assessed to be failing TOT. Further studies are needed to determine if HFOT can be used as an alternative to mechanical ventilation in resource limited settings and to characterize the complications associated with this therapy., (© Veterinary Emergency and Critical Care Society 2016.)

Perioperative complications commonly include oxygenation and ventilation abnormalities. The best outcome is associated with prevention. Ventilation impairment may be due to either neurologic compromise such as cervical intervertebral disk disease or severe parenchymal disease, while oxygenation failure may result from either the underlying disease or severe complications such as aspiration pneumonia, volume overload, pulmonary thromboembolism, or acute respiratory distress syndrome. This article reviews the approach to the patient with perioperative complications and provides recommendations on the management approach., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Objective: Hypoxemia is common during equine field anesthesia. Our hypothesis was that oxygen therapy from a portable oxygen concentrator would increase PaO2 during field anesthesia compared with the breathing of ambient air., Study Design: Prospective clinical study., Animals: Fifteen yearling (250 - 400 kg) horses during field castration., Methods: Horses were maintained in dorsal recumbency during anesthesia with an intravenous infusion of 2000 mg ketamine and 500 mg xylazine in 1 L of 5% guaifenesin. Arterial samples for blood gas analysis were collected immediately post-induction (PI), and at 15 and 30 minutes PI. The control group (n = 6) breathed ambient air. The treatment group (n = 9) were administered pulsed-flow oxygen (192 mL per bolus) by nasal insufflation during inspiration for 15 minutes PI, then breathed ambient air. The study was performed at 1300 m above sea level. One-way and two-way repeated-measures anova with post-hoc Bonferroni tests were used for within and between-group comparisons, respectively. Significance was set at p ≤ 0.05., Results: Mean ± SD PaO2 in controls at 0, 15 and 30 minutes PI were 46 ± 7 mmHg (6.1 ± 0.9 kPa), 42 ± 9 mmHg (5.6 ± 1.1 kPa), and 48 ± 7 mmHg (6.4 ± 0.1 kPa), respectively (p = 0.4). In treatment animals, oxygen administration significantly increased PaO2 at 15 minutes PI to 60 ± 13 mmHg (8.0 ± 1.7 kPa), compared with baseline values of 46 ± 8 mmHg (6.1 ± 1 kPa) (p = 0.007), and 30 minute PI values of 48 ± 7 mmHg (6.5 ± 0.9 kPa) (p = 0.003)., Conclusions: These data show that a pulsed-flow delivery of oxygen can increase PaO2 in dorsally recumbent horses during field anesthesia with ketamine-xylazine-guaifenesin., Clinical Relevance: The portable oxygen concentrator may help combat hypoxemia during field anesthesia in horses., (© 2015 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.)

This study documents the degree of positional atelectasis in sedated dogs receiving 100% oxygen (O(2)) versus room air. Initial lateral recumbency was determined by an orthopedic study and initial treatment (O(2) or room air) was randomized. Each dog was maintained in lateral recumbency for 15 min, at which time ventrodorsal (VD) and opposite lateral thoracic radiographs were obtained. Each dog was then maintained in the opposite lateral recumbency and received the other treatment for 15 min, followed by a VD and opposite lateral radiograph. Radiographs were scored for severity of pulmonary pattern and mediastinal shift by 3 radiologists. Dogs breathing O(2) had significantly higher scores than dogs breathing room air. If radiographically detectable dependent atelectasis is present, repeat thoracic images following manual positive ventilation and/or position change to the opposite lateral recumbency should be made to rule out the effect of O(2) positional atelectasis and avoid misdiagnosis.

Hypoxemia is anticipated during wildlife anesthesia and thus should be prevented. We evaluated the efficacy of low flow rates of supplemental oxygen for improvement of arterial oxygenation in anesthetized brown bears (Ursus arctos). The study included 32 free-ranging brown bears (yearlings, subadults, and adults; body mass 12-250 kg) that were darted with medetomidine-zolazepam-tiletamine (MZT) from a helicopter in Sweden. During anesthesia, oxygen was administered intranasally from portable oxygen cylinders at different flow rates (0.5-3 L/min). Arterial blood samples were collected before (pre-O2), during, and after oxygen therapy and immediately processed with a portable analyzer. Rectal temperature, respiratory rate, heart rate, and pulse oximetry-derived hemoglobin oxygen saturation were recorded. Intranasal oxygen supplementation at the evaluated flow rates significantly increased the partial pressure of arterial oxygen (PaO2) from pre-O2 values of 9.1 ± 1.3 (6.3-10.9) kPa to 20.4 ± 6.8 (11.1-38.7) kPa during oxygen therapy. When oxygen therapy was discontinued, the PaO2 decreased to values not significantly different from the pre-O2 values. In relation to the body mass of the bears, the following oxygen flow rates are recommended: 0.5 L/min to bears <51 kg, 1 L/min to bears 51-100 kg, 2 L/min to bears 101-200 kg, and 3 L/min to bears 201-250 kg. In conclusion, low flow rates of intranasal oxygen were sufficient to improve arterial oxygenation in brown bears anesthetized with MZT. Because hypoxemia quickly recurred when oxygen was discontinued, oxygen supplementation should be provided continuously throughout anesthesia.

Objective: To evaluate the influence of different inspired oxygen fractions (FiO2) on pulmonary oxygen exchange and Tei-index of myocardial performance in propofol-anesthetized dogs., Study Design: Prospective crossover, randomized, experimental trial., Animals: Eight adult dogs weighing 8.6 ± 1.8 kg., Methods: The animals were anesthetized on five occasions, receiving either an FiO2 = 1.0 (F100), 0.8 (F80), 0.6 (F60), 0.4 (F40) or 0.21 (F21). Propofol was used for induction (6.45 ± 0.69 mgkg(-1) IV) followed by a continuous rate infusion (CRI, 0.7 mgkg(-1) minute(-1)). The dogs breathed spontaneously. The initial measurements of arterial partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2), arterial hemoglobin saturation (SaO2), heart rate (HR), mean arterial pressure (MAP), cardiac index (CI), stroke index (SI), pre-ejection period (PEP) and left ventricular ejection time (LVET) were performed 30 minutes after beginning the CRI (T0) and then, at 15-minute intervals (T15-T60). From these measurements the following were calculated; alveolar oxygen partial pressure (PAO2), alveolar-arterial oxygen gradient (AaDO2), arterial oxygen partial pressure/inspired oxygen fraction ratio (PaO2/FiO2), arterial-to-alveolar oxygen tension ratio (PaO2/PAO2), respiratory index (RI), oxygen delivery (D·O2), PEP/LVET ratio, isovolumic relaxation time (IVRT) and Tei-index., Results: At T30, PaCO2 in F100 was higher than in F21. The AaDO2 mean in F100 was greater than in other treatments. PaO2/FiO2 in F21 was lower than F100 and F80 at T0 and than in F80 and F60 at T15. At T15, PaO2/PAO2 and RI in F100 were higher than in F80, F60 and F21. At T30, PaO2/PAO2 in F21 was lower than in F100 and F60. At T30, PEP/LVET in F100 was higher than F80, F40 and F21, which was lower than F80 and F40., Conclusion: The Tei-index and cardiovascular parameters are not affected by different FiO2., Clinical Relevance: An FiO2 of 1.0 and 0.21 impaired respiratory efficiency., (© 2013 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.)

Objective: To determine whether the ratio of pulse oximetry saturation/fraction of inspired oxygen (SpO2 /FiO2 , [SF]) correlates with the ratio of partial pressure of oxygen in arterial blood/FiO2 (PaO2 /FiO2 , [PF]) in dogs., Design: Prospective, observational pilot study., Setting: Urban tertiary veterinary referral center., Animals: Thirty-eight client-owned dogs requiring assessment of oxygenation., Interventions: None., Measurements and Main Results: Arterial blood gas analysis with co-oximetry was performed on samples obtained from the dorsal pedal artery. Median SpO2 was 91.5% (range 80-97%) and median PaO2 was 70.1 mmHg (range 44.5-103.8 mmHg). Hypoventilation was uncommon and venous admixture was the predominant cause of hypoxemia in this population. Median SF was 435.7 (range 381.0-461.9) and median PF was 334.0 (range 211.9-494.3). Nine dogs (23.6%) had PF <300; no dogs had PF below 200. SF and PF were correlated (ρ = 0.618, P < 0.01)., Conclusions: SF and PF in dogs spontaneously breathing room air have good correlation, suggesting that SF may be a useful, noninvasive surrogate for PF when assessing oxygenation in canine patients. Further studies are warranted to confirm and validate this relationship in spontaneously breathing and mechanically ventilated dogs on varying levels of FiO2 and to assess the ability of SF to predict outcome., (© Veterinary Emergency and Critical Care Society 2013.)

Objective: To evaluate physical examination findings and their association with carboxyhemoglobin (COHb) concentrations in 21 dogs that were exposed to smoke during a kennel fire., Series Summary: Twenty-one dogs were exposed to a kennel fire. Physical exam findings, presenting, and posttherapy COHb concentrations as well as therapeutic interventions were evaluated. COHb concentrations upon presentation were increased in all smoke inhalation exposed dogs. These dogs were compared to a small set of clinically normal staff-owned dogs who were not exposed to fire. Physical parameters significantly associated with higher COHb concentrations included lower body temperature, increased respiratory effort, abnormal respiratory auscultation, altered neurologic status, and length of hospital stay. Oxygen therapy resulted in a more rapid decline in COHb concentrations although 5 dogs still had mildly increased COHb concentrations 24-hour postadmission., Unique Information Provided: This study describes the relationship of admitting clinical findings of dogs exposed to a kennel fire with their initial blood COHb concentrations. It also describes the resolution of increased COHb concentrations with use of oxygen therapy and hospitalization. Additionally, COHb concentrations for a control group of dogs was evaluated and compared to the dogs exposed to smoke inhalation., (© Veterinary Emergency and Critical Care Society 2012.)

Portable battery-driven oxygen concentrators provide an alternative to the use of oxygen cylinders for treatment of hypoxemia during field anesthesia. The aim of this study was to evaluate the use of the EverGo Portable Oxygen Concentrator (Respironics, Murrysville, Pennsylvania 15668, USA) with pulse-dose delivery for improvement of arterial oxygenation during anesthesia of wildlife. This concentrator delivers oxygen in a pulsed flow with pulse volumes from 12 to 70 ml, up to a maximum capacity of 1.05 L/min. The pulse-dose setting shall be adjusted according to the respiratory rate of the animal, e.g., setting 6 for a respiratory rate < or = 15/min. The study included 16 free-ranging brown bears (Ursus arctos), 18 free-ranging bighorn sheep (Ovis canadensis), and five captive reindeer (Rangifer tarandus). Oxygen was administered via two nasal lines that were inserted through the nostrils to the level of the medial canthus of the eyes. Arterial blood samples were collected before, during, and after oxygen therapy and immediately analyzed. When providing oxygen from the portable concentrator, the arterial oxygenation markedly improved in all brown bears and some reindeer, whereas no or minor improvement was seen in the bighorn sheep. The mean +/- SD (range) PaO2 during oxygen supplementation was 134 +/- 29 (90-185) mmHg in the brown bears, 52 +/- 11 (32-67) mmHg in the bighorn sheep, and 79 +/- 19 (61-110) mmHg in the reindeer. The efficacy of the evaluated method may be influenced by ambient temperature, altitude, pulse-dose setting on the concentrator, the animal's respiratory rate, and species-specific physiology during anesthesia. Advantages of the portable oxygen concentrator included small size and low weight, ease of operate, and rechargeablity.

Objective: To compare tissue oxygen saturation in ovariohysterectomized dogs recovering postoperatively on room air versus nasal oxygen insufflation., Design: Prospective clinical study., Setting: University teaching hospital., Animals: Twenty dogs undergoing ovariohysterectomy., Interventions: Dogs were randomized to breathe either room air or 100 mL/kg/min of nasal oxygen insufflation for 2 hours postoperatively. Tissue oxygen saturation (StO(2)) was evaluated at 2 mm and 20 mm lateral to the surgical incision, as well as in the inguinal region using a noninvasive tissue oximeter., Measurements and Main Results: In dogs recovered on nasal oxygen insufflation (n = 10), tissue oxygen saturation was significantly higher--20 mm from the surgical site (88.44 ± 2.50%, P = 0.02) and in the inguinal region (83.56 ± 1.91%, P = 0.032)-- compared to dogs recovered on room air (n = 10, 79.11% ± 2.50 and 77.12% ± 1.91, respectively)., Conclusions: In ovariohysterectomized dogs, oxygen supplementation for 2 hours postoperatively improves tissue oxygen saturation 20 mm adjacent to the linea alba and in the inguinal region. Oxygen supplementation in postoperative dogs is an inexpensive and easily applicable method to improve tissue oxygen saturation., (© Veterinary Emergency and Critical Care Society 2011.)

Objective: To describe the medical management of pneumoperitoneum without surgical intervention in a dog that sustained blunt force trauma to the thorax. To review the mechanisms of how a thoracic injury (ie, extra-abdominal source) can lead to pneumoperitoneum., Case Summary: A 4-month-old Shih Tzu puppy was attacked by a larger dog and sustained various injuries including a pneumothorax, pneumomediastinum, and a pneumoperitoneum. The dog presented minimally responsive and in respiratory distress secondary to pulmonary contusions and noncardiogenic pulmonary edema. No penetrating wounds to the abdomen or thorax were identified. As no immediate surgical lesion was identified the dog was treated conservatively without the need for surgical intervention. The dog was successfully managed and discharged after a few days of supportive care with oxygen therapy. Before discharge, repeat radiographs revealed complete resolution of the pneumothorax, pneumomediastinum, and pneumoperitoneum., New or Unique Information Provided: Cases of nonsurgical pneumoperitoneum have rarely been reported in the veterinary literature. A thoracic source of pneumoperitoneum should be considered when the suspicion of a ruptured viscus is low based on diagnostic procedures (eg, ultrasound, computed tomography, and diagnostic peritoneal lavage), in addition to physical examination (eg, lack of fever and absence of abdominal pain) and laboratory findings (eg, absence of inflammatory leukogram)., (© Veterinary Emergency and Critical Care Society 2011.)

After an uneventful general anesthesia, in a horse negative pressure pulmonary edema developed due to acute upper airway obstruction during the anesthetic recovery phase after colic surgery. No pathologic alteration of respiration was observed until the horse stood up and began suffocating. The horse had recovered with the nasogastric tube in situ. This, together with the postmortem diagnosis of laryngeal hemiplegia resulted in impairment of airflow through the larynx and development of pulmonary edema. Our objective is to alert clinicians about the possible hazard of recovery with an in-situ nasogastric tube.

Background: The purpose of this study was to compare the effects of 0.5 fraction of inspired oxygen (FiO₂) and >0.95 FiO₂ on pulmonary gas exchange, shunt fraction and oxygen delivery (DO₂) in dorsally recumbent horses during inhalant anesthesia. The use of 0.5 FiO₂ has the potential to reduce absorption atelectasis (compared to maximal FiO₂) and augment alveolar oxygen (O₂) tensions (compared to ambient air) thereby improving gas exchange and DO₂. Our hypothesis was that 0.5 FiO₂ would reduce ventilation-perfusion mismatching and increase the fraction of pulmonary blood flow that is oxygenated, thus improving arterial oxygen content and DO₂., Results: Arterial partial pressures of O₂ were significantly higher than preanesthetic levels at all times during anesthesia in the >0.95 FiO₂ group. Arterial partial pressures of O₂ did not change from preanesthetic levels in the 0.5 FiO₂ group but were significantly lower than in the >0.95 FiO₂ group from 15 to 90 min of anesthesia. Alveolar to arterial O₂ tension difference was increased significantly in both groups during anesthesia compared to preanesthetic values. The alveolar to arterial O₂ tension difference was significantly higher at all times in the >0.95 FiO₂ group compared to the 0.5 FiO2 group. Oxygen delivery did not change from preanesthetic values in either group during anesthesia but was significantly lower than preanesthetic values 10 min after anesthesia in the 0.5 FiO₂ group. Shunt fraction increased in both groups during anesthesia attaining statistical significance at varying times. Shunt fraction was significantly increased in both groups 10 min after anesthesia but was not different between groups. Alveolar dead space ventilation increased after 3 hr of anesthesia in both groups., Conclusions: Reducing FiO₂ did not change alveolar dead space ventilation or shunt fraction in dorsally recumbent, mechanically ventilated horses during 3 hr of isoflurane anesthesia. Reducing FiO₂ in dorsally recumbent isoflurane anesthetized horses does not improve oxygenation or oxygen delivery.

Respiratory distress is usually a life-threatening emergency in any species and this is particularly important in avian species because of their unique anatomy and physiology. In the emergency room, observation of breathing patterns, respiratory sounds, and a brief physical examination are the most important tools for the diagnosis and treatment of respiratory distress in avian patients. These tools will help the clinician localize the lesion. This discussion focuses on the 5 anatomic divisions of the respiratory system and provides clinically important anatomic and physiologic principles and diagnosis and treatment protocols for the common diseases occurring in each part., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Perinatal asphyxia is one of the leading causes of morbidity and mortality in the neonatal period. Response to oxygen treatment is unpredictable and the optimum concentration of oxygen in neonatal resuscitation is still a matter of debate among neonatologists. A metabolomic approach was used to characterize the metabolic profiles of newborn hypoxic-reoxygenated piglets. Urine samples were collected from newborn piglets (n = 40) undergoing hypoxia followed by resuscitation at different oxygen concentrations (ranging from 18% to 100%) and analyzed by ¹H NMR spectroscopy. Despite reoxygenation 7 piglets, out of 10 which became asystolic, did not respond to resuscitation. Profiles of the ¹H NMR spectra were submitted to unsupervised (principal component analysis) and supervised (partial least squares-discriminant analysis) multivariate analysis. The supervised analyses showed differences in the metabolic profile of the urine collected before the induction of hypoxia between survivors and deaths. Metabolic variations were observed in the urine of piglets treated with different oxygen concentrations comparing T0 (basal value) and end of the experiment (resuscitation). Some of the individual metabolites discriminating between these groups were urea, creatinine, malonate, methylguanidine, hydroxyisobutyric acid. The metabolomic approach appears a promising tool for investigating newborn hypoxia over time, for monitoring the response to the treatment with different oxygen concentrations, and might lead to a tailored management of the disorder.

Objective: To describe the successful management of cardiac arrest following accidental venous air embolism (VAE) in a cat., Case Summary: A 3-year-old spayed female domestic shorthair cat, weighing 4 kg, was presented for continuation of its chemotherapy protocol. The cat was inadvertently administered approximately 5.5 mL of air IV during initiation of fluid therapy. Immediate cardiac arrest resulted and CPR successfully achieved return of spontaneous circulation. The cat was discharged 5 days later and is reportedly clinically normal 7 months post-discharge., New or Unique Information Provided: VAE has been rarely reported in the veterinary literature. This is the first report of a cat surviving cardiac arrest secondary to VAE.

This study assessed whether arterial oxygenation could be increased by treatment with intranasal oxygen supplementation in brown bears (Ursus arctos) with hypoxemia during anesthesia with medetomidine-zolazepam-tiletamine. Arterial blood samples were collected anaerobically from the femoral artery before and during oxygen supplementation. An oxygen flow rate of 2-5 L/min administered intranasally to brown bears weighing 12-120 kg markedly increased arterial oxygenation. Intranasal oxygen supplementation proved to be a simple and efficient method for treatment of hypoxemia in anesthetized bears.

Drowning is potentially fatal. Physiologic responses to aspiration of water differ according to whether the water is salt or fresh; whether these responses are significant depends on the volume of fluid aspirated. Resuscitation efforts should be started at the scene of the accident. Oxygen therapy is essential. Many patients require continuous positive airway pressure or positive end-expiratory pressure to reverse hypoxemia. Physiologic responses induced by ice-water submersion can be protective during the initial insult. The prognosis for submersion injuries is guarded and is influenced by several variables.

Oxygenation status was evaluated in medetomidine-sedated dogs breathing room air (M) or 100 percent oxygen (MO2). Medetomidine (40 microg/kg IV) administration resulted in peripheral vasoconstriction and decreased venous saturation as measured by an increased oxygen extraction ratio in peripheral tissues. Providing 100 percent oxygen insufflation via face mask reduced desaturation by increasing oxygen content but did not prevent vasoconstriction or reduce the oxygen extraction ratio in peripheral tissues. Atipamezole (200 microg/kg IV) reversed medetomidine-induced vasoconstriction and increased oxygen supply to tissues as indicated by a lower tissue oxygen extraction ratio. The authors conclude that 100 percent oxygen insufflation via face mask during medetomidine sedation (40 micrograms/kg [corrected] IV) benefits tissue oxygenation in healthy dogs.