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The carotid bodies are the primary sensors of blood pH, pO2 and pCO2. The ganglioglomerular nerve (GGN) provides post-ganglionic sympathetic nerve input to the carotid bodies, however the physiological relevance of this innervation is still unclear. The main objective of this study was to determine how the absence of the GGN influences the hypoxic ventilatory response in juvenile rats. As such, we determined the ventilatory responses that occur during and following five successive episodes of hypoxic gas challenge (HXC, 10% O2, 90% N2), each separated by 15 min of room-air, in juvenile (P25) sham-operated (SHAM) male Sprague Dawley rats and in those with bilateral transection of the ganglioglomerular nerves (GGNX). The key findings were that 1) resting ventilatory parameters were similar in SHAM and GGNX rats, 2) the initial changes in frequency of breathing, tidal volume, minute ventilation, inspiratory time, peak inspiratory and expiratory flows, and inspiratory and expiratory drives were markedly different in GGNX rats, 3) the initial changes in expiratory time, relaxation time, end inspiratory or expiratory pauses, apneic pause and noneupneic breathing index (NEBI) were similar in SHAM and GGNX rats, 4) the plateau phases obtained during each HXC were similar in SHAM and GGNX rats, and 5) the ventilatory responses that occurred upon return to room-air were similar in SHAM and GGNX rats. Overall, these changes in ventilation during and following HXC in GGNX rats raises the possibility the loss of GGN input to the carotid bodies effects how primary glomus cells respond to hypoxia and the return to room-air. [ABSTRACT FROM AUTHOR]

The carotid bodies are the primary sensors of blood pH, pO2 and pCO2. The ganglioglomerular nerve (GGN) provides post-ganglionic sympathetic nerve input to the carotid bodies, however the physiological relevance of this innervation is still unclear. The main objective of this study was to determine how the absence of the GGN influences the hypoxic ventilatory response in juvenile rats. As such, we determined the ventilatory responses that occur during and following five successive episodes of hypoxic gas challenge (HXC, 10% O2, 90% N2), each separated by 15 min of room-air, in juvenile (P25) sham-operated (SHAM) male Sprague Dawley rats and in those with bilateral transection of the ganglioglomerular nerves (GGNX). The key findings were that 1) resting ventilatory parameters were similar in SHAM and GGNX rats, 2) the initial changes in frequency of breathing, tidal volume, minute ventilation, inspiratory time, peak inspiratory and expiratory flows, and inspiratory and expiratory drives were markedly different in GGNX rats, 3) the initial changes in expiratory time, relaxation time, end inspiratory or expiratory pauses, apneic pause and non-eupneic breathing index (NEBI) were similar in SHAM and GGNX rats, 4) the plateau phases obtained during each HXC were similar in SHAM and GGNX rats, and 5) the ventilatory responses that occurred upon return to room-air were similar in SHAM and GGNX rats. Overall, these changes in ventilation during and following HXC in GGNX rats raises the possibility the loss of GGN input to the carotid bodies effects how primary glomus cells respond to hypoxia and the return to room-air.

Thiago De Marchi,1,2 Fabiano Frâncio,1,3 João Vitor Ferlito,3 Renata Weigert,3 Cristiane de Oliveira,3 Ana Paula Merlo,3 Délcio Luis Pandini,3 Bolivar Antônio Pasqual-Júnior,3 Daniela Giovanella,3 Shaiane Silva Tomazoni,4,5 Ernesto Cesar Leal-Junior2,4,5 1University Center of Bento Gonçalves (UNICNEC), Bento Gonçalves, Rio Grande do Sul, Brazil; 2Laboratory of Phototherapy and Innovative Technologies in Health (LaPIT), Post-graduate Program in Rehabilitation Sciences, Nove de Julho University, São Paulo, Brazil; 3Hospital Tacchini, Bento Gonçalves, Rio Grande do Sul, Brazil; 4Physiotherapy Research Group, Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway; 5ELJ Consultancy, Scientific Consultants, São Paulo, BrazilCorrespondence: Shaiane Silva TomazoniPhysiotherapy Research Group, Department of Global Public Health and Primary Care, University of Bergen, Alrek helseklynge, blokk D, Årstadveien 17, Bergen, NO-5020, NorwayEmail shaiane.tomazoni@eljconsultancy.comPurpose: We aimed to investigate the effects of photobiomodulation therapy combined with static magnetic field (PBMT-sMF) on the length of intensive care unit (ICU) stay and mortality rate of severe COVID-19 patients requiring invasive mechanical ventilation and assess its role in preserving respiratory muscles and modulating inflammatory processes.Patients and Methods: We conducted a prospectively registered, triple-blinded, randomized, placebo-controlled trial of PBMT-sMF in severe COVID-19 ICU patients requiring invasive mechanical ventilation. Patients were randomly assigned to receive either PBMT-sMF or a placebo daily throughout their ICU stay. The primary outcome was length of ICU stay, defined by either discharge or death. The secondary outcomes were survival rate, diaphragm muscle function, and the changes in blood parameters, ventilatory parameters, and arterial blood gases.Results: Thirty patients were included and equally randomized into the two groups. There were no significant differences in the length of ICU stay (mean difference, MD = − 6.80; 95% CI = − 18.71 to 5.11) between the groups. Among the secondary outcomes, significant differences were observed in diaphragm thickness, fraction of inspired oxygen, partial pressure of oxygen/fraction of inspired oxygen ratio, C-reactive protein levels, lymphocyte count, and hemoglobin (p < 0.05).Conclusion: Among severe COVID-19 patients requiring invasive mechanical ventilation, the length of ICU stay was not significantly different between the PBMT-sMF and placebo groups. In contrast, PBMT-sMF was significantly associated with reduced diaphragm atrophy, improved ventilatory parameters and lymphocyte count, and decreased C-reactive protein levels and hemoglobin count.Trial Registration Number (Clinical Trials.gov): NCT04386694.Keywords: COVID-19, photobiomodulation, intensive care unit, respiratory muscles, ventilatory parameters, mechanical ventilation

Continuous monitoring of ventilatory parameters such as tidal volume (TV) and minute ventilation (MV) has shown to be effective in the prevention of respiratory compromise events in hospitalized patients. However, the non-invasive estimation of respiratory volume in non-intubated patients remains an outstanding challenge. In this work, we present a novel approach to respiratory volume monitoring (RVM) that continuously predicts TV and MV in normal subjects. Respiratory flow in 19 volunteers under spontaneous breathing was recorded using respiratory inductance plethysmography and a temperature-based wearable sensor. Temperature signals were processed to identify features such as temperature amplitude and mean value, among others. The feature datasets were then used to train and validate three machine-learning (ML) algorithms for the prediction of respiratory volume based on temperature-related features. A model based on Random-Forest regression resulted in the lowest root mean-square error and was subsequently chosen to predict ventilatory parameters on subject test data not used in the construction of the model. Our predictions achieve a bias (mean error) in TV and MV of 16.04 mL and 0.19 L/min, respectively, which compare well with performance metrics reported in commercially-available RVM systems based on electrical impedance. Our results show that the combination of novel respiratory temperature sensors and machine-learning algorithms can deliver accurate and continuous estimates of TV and MV in healthy subjects.

There is an urgent need to understand the intracellular mechanisms by which synthetic opioids, such as fentanyl, depress breathing. We used L-NAME (NG-nitro-L-arginine methyl ester), a nitric oxide synthase (NOS) inhibitor, to provide evidence for a role of nitric oxide (NO) and nitrosyl factors, including S-nitrosothiols, in fentanyl-induced suppression of breathing in rats. We measured breathing parameters using unrestrained plethysmography to record the changes produced by bolus administration of fentanyl (25 μg/kg, IV) in male Sprague Dawley rats that were pretreated with vehicle (saline), L-NAME (50 μmol/kg, IV) or the inactive D-isomer, D-NAME (50 μmol/kg, IV), 15 min previously. L-NAME produced a series of ventilatory changes that included (i) sustained elevations in breathing frequency, due to the reductions in the durations of inspiration and expiration, (ii) sustained elevations in minute ventilation, accompanied by minimal changes in tidal volume, and (iii) increases in inspiratory drive and expiratory drive, and peak inspiratory flow and peak expiratory flow. Subsequent administration of fentanyl in rats pretreated with vehicle produced negative effects on breathing, including decreases in frequency, tidal volume and therefore minute ventilation. Fentanyl elicited markedly different responses in rats that were pretreated with L-NAME, and conclusively, the negative effects of fentanyl were augmented by the NOS inhibitor. D-NAME did not alter ventilatory parameters or modulate the effects of fentanyl on breathing. Our study fully characterized the effects of L-NAME on ventilation in rats and is the first to suggest a potential role of nitrosyl factors in the ventilatory responses to fentanyl. Our data shows that nitrosyl factors reduce the expression of fentanyl-induced changes in ventilation.

Arterial pCO2 elevations increase minute ventilation via activation of chemosensors within the carotid body (CB) and brainstem. Although the roles of CB chemoafferents in the hypercapnic (HC) ventilatory response have been investigated, there are no studies reporting the role of these chemoafferents in the ventilatory responses to a HC challenge or the responses that occur upon return to room air, in freely moving mice. This study found that an HC challenge (5% CO2, 21% O2, 74% N2 for 15 min) elicited an array of responses, including increases in frequency of breathing (accompanied by decreases in inspiratory and expiratory times), and increases in tidal volume, minute ventilation, peak inspiratory and expiratory flows, and inspiratory and expiratory drives in sham-operated (SHAM) adult male C57BL6 mice, and that return to room air elicited a brief excitatory phase followed by gradual recovery of all parameters toward baseline values over a 15-min period. The array of ventilatory responses to the HC challenge in mice with bilateral carotid sinus nerve transection (CSNX) performed 7 days previously occurred more slowly but reached similar maxima as SHAM mice. A major finding was responses upon return to room air were dramatically lower in CSNX mice than SHAM mice, and the parameters returned to baseline values within 1-2 min in CSNX mice, whereas it took much longer in SHAM mice. These findings are the first evidence that CB chemoafferents play a key role in initiating the ventilatory responses to HC challenge in C57BL6 mice and are essential for the expression of post-HC ventilatory responses. [ABSTRACT FROM AUTHOR]

The cervical sympathetic chain (CSC) innervates post-ganglionic sympathetic neurons within the ipsilateral superior cervical ganglion (SCG) of all mammalian species studied to date. The post-ganglionic neurons within the SCG project to a wide variety of structures, including the brain (parenchyma and cerebral arteries), upper airway (e.g., nasopharynx and tongue) and submandibular glands. The SCG also sends post-ganglionic fibers to the carotid body (e.g., chemosensitive glomus cells and microcirculation), however, the function of these connections are not established in the mouse. In addition, nothing is known about the functional importance of the CSC-SCG complex (including input to the carotid body) in the mouse. The objective of this study was to determine the effects of bilateral transection of the CSC on the ventilatory responses [e.g., increases in frequency of breathing (Freq), tidal volume (TV) and minute ventilation (MV)] that occur during and following exposure to a hypoxic gas challenge (10% O2 and 90% N2) in freely-moving sham-operated (SHAM) adult male C57BL6 mice, and in mice in which both CSC were transected (CSCX). Resting ventilatory parameters (19 directly recorded or calculated parameters) were similar in the SHAM and CSCX mice. There were numerous important differences in the responses of CSCX and SHAM mice to the hypoxic challenge. For example, the increases in Freq (and associated decreases in inspiratory and expiratory times, end expiratory pause, and relaxation time), and the increases in MV, expiratory drive, and expiratory flow at 50% exhaled TV (EF50) occurred more quickly in the CSCX mice than in the SHAM mice, although the overall responses were similar in both groups. Moreover, the initial and total increases in peak inspiratory flow were higher in the CSCX mice. Additionally, the overall increases in TV during the latter half of the hypoxic challenge were greater in the CSCX mice. The ventilatory responses that occurred upon return to room-air were essentially similar in the SHAM and CSCX mice. Overall, this novel data suggest that the CSC may normally provide inhibitory input to peripheral (e.g., carotid bodies) and central (e.g., brainstem) structures that are involved in the ventilatory responses to hypoxic gas challenge in C57BL6 mice.

The cervical sympathetic chain (CSC) innervates post-ganglionic sympathetic neurons within the ipsilateral superior cervical ganglion (SCG) of all mammalian species studied to date. The post-ganglionic neurons within the SCG project to a wide variety of structures, including the brain (parenchyma and cerebral arteries), upper airway (e.g., nasopharynx and tongue) and submandibular glands. The SCG also sends post-ganglionic fibers to the carotid body (e.g., chemosensitive glomus cells and microcirculation), however, the function of these connections are not established in the mouse. In addition, nothing is known about the functional importance of the CSC-SCG complex (including input to the carotid body) in the mouse. The objective of this study was to determine the effects of bilateral transection of the CSC on the ventilatory responses [e.g., increases in frequency of breathing (Freq), tidal volume (TV) and minute ventilation (MV)] that occur during and following exposure to a hypoxic gas challenge (10% O2 and 90% N2) in freely-moving sham-operated (SHAM) adult male C57BL6 mice, and in mice in which both CSC were transected (CSCX). Resting ventilatory parameters (19 directly recorded or calculated parameters) were similar in the SHAM and CSCX mice. There were numerous important differences in the responses of CSCX and SHAM mice to the hypoxic challenge. For example, the increases in Freq (and associated decreases in inspiratory and expiratory times, end expiratory pause, and relaxation time), and the increases in MV, expiratory drive, and expiratory flow at 50% exhaled TV (EF50) occurred more quickly in the CSCX mice than in the SHAM mice, although the overall responses were similar in both groups. Moreover, the initial and total increases in peak inspiratory flow were higher in the CSCX mice. Additionally, the overall increases in TV during the latter half of the hypoxic challenge were greater in the CSCX mice. The ventilatory responses that occurred upon return to room-air were essentially similar in the SHAM and CSCX mice. Overall, this novel data suggest that the CSC may normally provide inhibitory input to peripheral (e.g., carotid bodies) and central (e.g., brainstem) structures that are involved in the ventilatory responses to hypoxic gas challenge in C57BL6 mice. [ABSTRACT FROM AUTHOR]

Maternal undernutrition may cause injuries in several organs of the offspring, as well as lead to diseases in adulthood. Obesity and/or the consumption of a high‐fat diet may also induce metabolic and cardiorespiratory diseases. We hypothesized that the consumption of a post‐weaning high‐fat diet would potentiate the deleterious effects of maternal protein undernutrition. This study evaluated the effects of the association of a low‐protein diet during gestation and lactation with a post‐weaning high‐fat diet on the biochemical and ventilatory parameters of rats. Male Wistar rats from mothers who received a low‐protein (9% of protein) or normoprotein diet during pregnancy and lactation received a high‐fat (32% of total kilocalories from lipids) or a normal fat diet after weaning. Mass gain and somatic growth of the offspring were monitored. Also examined were biochemical chemical parameters and respiratory frequency, tidal volume (volume of air displaced in each normal respiratory cycle when extra effort is not applied), and pulmonary ventilation. Offspring from undernourished mothers presented lower birth weight (P =.0225), which remained until the end of lactation (P <.01). The rats that consumed high‐fat diet and had been submitted to maternal undernutrition presented higher tidal volume when compared to the ones that consumed control diet at the 21st day of life (P ˂.05). At 30 and 90 days, no further ventilatory changes were observed. Our data show that the consumption of a high‐fat diet post‐weaning did not seem to potentiate the changes induced by maternal undernutrition. [ABSTRACT FROM AUTHOR]

Background: Respiratory muscle strength can be decreased in patients with asthma; however, it is not well-documented whether a mild bronchial asthma disease can affect respiratory muscle strength in children and can be associated with higher presence of breathing difficulties. Objective: The main aim of the present study was to compare respiratory muscle strength between children with asthma and age-matched healthy children. The next aim of this study was to assess the incidence of decreased respiratory muscle strength in children with asthma and healthy children and assess the effect of decreased respiratory muscle strength on the incidence of breathing difficulties. Methods: Children with mild bronchial asthma (n = 167) and age-matched, healthy children (n = 100) were recruited into this study. Pulmonary function tests, maximal inspiratory (PImax) and expiratory (PEmax) mouth pressures and the incidence of breathing difficulty were evaluated in children with asthma and healthy controls. Results: The inspiratory muscle strength was similar between children with asthma and healthy children. Conversely, the expiratory muscle strength was lower in asthmatic children. There was a statistically significant difference between girls with asthma and healthy girls (PEmax = 81.7 ± 29.8% vs. 100.1 ± 23.7% of predicted, p max was significantly higher in boys with asthma than in girls with asthma (PEmax = 92.9 ± 26.4 % vs. 81.7 ± 29.8% of predicted, p = .03). A higher incidence of breathing difficulties during physical activity (uphill walking, running, swimming) was confirmed in children with asthma with lower respiratory muscle strength. Conclusions: There was a higher prevalence of decreased expiratory muscle strength in children with asthma; therefore, respiratory muscle strength should be tested in these children, especially in those who are symptomatic.

Mechanical ventilation (MV) is widely used in hospitals or in intensive care units in patients with acute respiratory failure (ARF). The efficiency of mechanical ventilation depends on frequent manual adjustments by trained professionals and in accordance with the patient's physiological signals. This task implies a specialized, constant and exhaustive work. This paper proposes an artificial neural network (RNA) model for automatic parametrization of the mechanical ventilator aiming to maintain adequate ventilation of the patient plus the optimization of human resources in the health area. [ABSTRACT FROM AUTHOR]

Objective: To assess respiratory function and functional capacity in children with pectus excavatum who followed a physical therapy program, to compare these parameters to healthy controls and to evaluate adherence of this category of patients (pectus excavatum without surgical indications) to a supervised exercise program.Methods: This study included 14 children with pectus excavatum and 14 gender and age-matched healthy controls. The study patients performed a 12-week exercise program. They were assessed at the beginning and at the end of rehabilitation by spirometry and functional capacity testing (6-min walk test). Parents of children with pectus excavatum completed a 10-item adherence questionnaire.Results: In the study patients all respiratory parameters increased after rehabilitation. After 12 weeks there were no differences between study patients and controls, except for functional capacity that still had lower values in children with pectus excavatum. The parents of all patients agreed about fitting of the training program with their child's daily routine, low difficulty of the exercises, the child following the physiotherapist's instructions and confidence in the results of rehabilitation.Conclusions: In children with pectus excavatum without surgical indications, forced vital capacity, forced expiratory volume in 1 s and functional capacity assessed by the 6‑min walk test improved significantly after a 12-week supervised exercise program. The study showed that adherence to the exercise-based program was good for all patients. [ABSTRACT FROM AUTHOR]

Background and Aims : Laryngeal mask airway (LMA) cuff pressure increases when the air is used for the cuff inflation during oxygen: nitrous oxide (O 2 :N 2 O) anaesthesia, which may lead to various problems. We compared the effects of different gases for ProSeal LMA™ (PLMA) cuff inflation in adult patients for various parameters. Methods: A total of 120 patients were randomly allocated to four groups, according to composition of gases used to inflate the PLMA cuff to achieve 40 cmH 2 O cuff pressure, air (Group A), 50% O 2 :air (Group OA), 50% O 2 :N 2 O (Group ON) and 100% O 2 (Group O). Cuff pressure, cuff volume and ventilator parameters were monitored intraoperatively. Pharyngolaryngeal parameters were assessed at 1, 2 and 24 h postoperatively. Statistical analysis was performed using ANOVA, Fisher′s exact test and step-wise logistic regression. Results: Cuff pressure significantly increased at 10, 15 and 30 min in Group A, OA and O from initial pressure. Cuff pressure decreased at 5 min in Group ON (36.6 ± 3.5 cmH 2 O) (P = 0.42). PLMA cuff volume increased in Group A, OA, O, but decreased in Group ON (6.16 ± 2.8 ml [P < 0.001], 4.7 ± 3.8 ml [P < 0.001], 1.4 ± 3.19 ml [P = 0.023] and − 1.7 ± 4.9 ml [P = 0.064], respectively), from basal levels. Ventilatory parameters were comparable in all four groups. There was no significant association between sore throat and cuff pressure, with odds ratio 1.002. Conclusion: Cuff inflation with 50% O 2 :N 2 O mixture provided more stable cuff pressure in comparison to air, O 2 :air, 100% O 2 during O 2 :N 2 O anaesthesia. Ventilatory parameters did not change with variation in PLMA cuff pressure. Post-operative sore throat had no correlation with cuff pressure.

Background and Aims: Studies have demonstrated minimal hemodynamic variation and postoperative complications with ProSeal laryngeal mask airway (PLMA) compared to endotracheal tube (ETT). Hence, a study was conducted to compare the ventilatory parameters and airway dynamics required to maintain normocarbia and stable hemodynamics with PLMA and ETT. Material and Methods: A prospective, randomized, single blinded study was conducted on 60 patients aged 20-40 years of American society of anesthesiologists class I and II, divided into Group PLMA and Group ETT. Standard anesthesia protocol was instituted. Group PLMA received PLMA sizes as per manufacturer′s recommendations and group ETT received appropriate sized cuffed ETT. Patients were initially ventilated at 14 bpm, I:E ratio 1:2, tidal volume (Vt) 6 ml/kg and later adjusted to maintain end tidal carbon dioxide (EtCO 2 ) between 35 and 40 mmHg. Peak airway pressure (Ppeak), compliance (Compl.), Vt, airway resistance (R aw ), hemodynamic parameters, oxygen saturation (SpO 2 ) and EtCO 2 were recorded throughout surgery. Postoperative complications if any, were noted. Results: Demographic parameters, R aw , EtCO 2 , SpO 2 were comparable between groups. Ppeak was lower and Vt needed to maintain EtCO 2 of 35-40 mmHg was lesser in Group PLMA. Compl was low for 5 min after insertion of PLMA. Heart rate was significantly reduced at 1 min post insertion; blood pressures were significantly lower upto 2 min after insertion and post removal in group PLMA. Incidence of cough was significantly lower in group PLMA. Conclusion: ProSeal laryngeal mask airway maintains adequate ventilation at lower Vts and minimal peak pressures, has lesser hemodynamic variations and lower incidence of postoperative cough compared to ETT.

Background: The SERVE-HF study has raised questions concerning the higher mortality under adaptive servoventilation. The ventilatory mode was discussed as a possible aggravating factor. Objectives: We wondered if the data recorded by the adaptive servo-ventilation (ASV)-devices in heart failure patients with CSA-CSR ± OSA are different in terms of respiratory parameters and therapeutic pressures compared to patients with CPAP-resistant/emergent-CSA with normal BNP/NT-pro-BNP. Methods: Patients were included, if ASV had normalized respiratory disturbance index in the first night of application and after at least 6 weeks. ASV-device data were analyzed in terms of respiratory rate (RR), min ventilation (MV), endexpiratory (EEP), peak inspiratory pressure (Ppeak) and median pressure. Results: Compared to CPAP-resistant/emergent-CSA with normal BNP/NT-pro-BNP (n = 25), CSA-CSR- (n = 13) CSA-CSR+OSA-patients (n = 32) with elevated BNP/NT-pro-BNP had higher RR (p < 0.01) in the first night of ASV therapy and during follow-up (15.3 ± 1.3 vs. 17.3 ± 2.4/min) with similar MV (6.5 ± 1.3 vs. 6.6 ± 1.3 L), resulting in significantly lower tidal volumes. EEP (5.6 ± 1.1 vs. 5.5 ± 1.1 hPa), Pmedian and Ppeak (9.8 ± 1.5 vs. 9.7 ± 1.2 hPa) were comparable. Ventilatory parameters were not different between LVEF < 40, 40–49, and ≥50%, neither within the whole group nor the group of CSA-CSR ± OSA and heart failure. Conclusion: Patients with heart failure and CSA-CSR ± OSA have higher RRs but similar MV under ASV-therapy than patients with CSA and normal BNP. This indicates higher dead space ventilation. EF was not found to have an influence on the ventilatory parameters. [ABSTRACT FROM AUTHOR]

Although respiratory muscle functions can influence swimming performance, respiratory muscle training (RMT) is not routinely used for improving fin-swimmers' performance. The aim of our study was to verify the benefit of a one month of RMT in young fin-swimmers. We assessed the effect of this training on respiratory muscles and on maximal underwater swimming distance. 28 fin-swimmers were randomly divided into an experimental group (EG) and a control group (CG). The study finished with 20 fin-swimmers (EG: n = 12; average age 12.0; weight 47.4 kg; height 1.58 m; CG: n = 8; age 11.5; weight 49.6 kg; height 1.53 m). Both group performed regular swimming training, during which the EG used Threshold PEP (positive expiratory pressure) and IMT (inspiratory muscle trainer) for RMT for one month. After one-month washout period, the CG also performed RMT. RMT showed significant improvement of inspiratory muscles in both groups (Z = <1.96; 2.59>; p < 0.05). Significant improvement was observed also in apnoea (AP) max (ZCG = 2.03; p < 0.05; ZEG=2.93; p < 0.01). A long-term effect was observed in the respiratory muscle strength and AP max in the EG (ZEG = 2.52; p < 0.05). RMT in fin-swimmers improves both respiratory muscle strength and the performance in AP max. [ABSTRACT FROM AUTHOR]

Background: Respiratory muscle strength can be decreased in patients with asthma; however, it is not well-documented whether a mild bronchial asthma disease can affect respiratory muscle strength in children and can be associated with higher presence of breathing difficulties. Objective: The main aim of the present study was to compare respiratory muscle strength between children with asthma and age-matched healthy children. The next aim of this study was to assess the incidence of decreased respiratory muscle strength in children with asthma and healthy children and assess the effect of decreased respiratory muscle strength on the incidence of breathing difficulties. Methods: Children with mild bronchial asthma (n = 167) and age-matched, healthy children (n = 100) were recruited into this study. Pulmonary function tests, maximal inspiratory (PImax) and expiratory (PEmax) mouth pressures and the incidence of breathing difficulty were evaluated in children with asthma and healthy controls. Results: The inspiratory muscle strength was similar between children with asthma and healthy children. Conversely, the expiratory muscle strength was lower in asthmatic children. There was a statistically significant difference between girls with asthma and healthy girls (PEmax = 81.7 ± 29.8% vs. 100.1 ± 23.7% of predicted, p < .001). PEmax was significantly higher in boys with asthma than in girls with asthma (PEmax = 92.9 ± 26.4 % vs. 81.7 ± 29.8% of predicted, p = .03). A higher incidence of breathing difficulties during physical activity (uphill walking, running, swimming) was confirmed in children with asthma with lower respiratory muscle strength. Conclusions: There was a higher prevalence of decreased expiratory muscle strength in children with asthma; therefore, respiratory muscle strength should be tested in these children, especially in those who are symptomatic. [ABSTRACT FROM AUTHOR]

Background and Aims: Laryngeal mask airway (LMA) cuff pressure increases when the air is used for the cuff inflation during oxygen: nitrous oxide (O2:N2O) anaesthesia, which may lead to various problems. We compared the effects of different gases for ProSeal LMA™ (PLMA) cuff inflation in adult patients for various parameters. Methods: A total of 120 patients were randomly allocated to four groups, according to composition of gases used to inflate the PLMA cuff to achieve 40 cmH2O cuff pressure, air (Group A), 50% O2:air (Group OA), 50% O2:N2O (Group ON) and 100% O2 (Group O). Cuff pressure, cuff volume and ventilator parameters were monitored intraoperatively. Pharyngolaryngeal parameters were assessed at 1, 2 and 24 h postoperatively. Statistical analysis was performed using ANOVA, Fisher's exact test and step-wise logistic regression. Results: Cuff pressure significantly increased at 10, 15 and 30 min in Group A, OA and O from initial pressure. Cuff pressure decreased at 5 min in Group ON (36.6 ± 3.5 cmH2O) (P = 0.42). PLMA cuff volume increased in Group A, OA, O, but decreased in Group ON (6.16 ± 2.8 ml [P < 0.001], 4.7 ± 3.8 ml [P < 0.001], 1.4 ± 3.19 ml [P = 0.023] and - 1.7 ± 4.9 ml [P = 0.064], respectively), from basal levels. Ventilatory parameters were comparable in all four groups. There was no significant association between sore throat and cuff pressure, with odds ratio 1.002. Conclusion: Cuff inflation with 50% O2:N2O mixture provided more stable cuff pressure in comparison to air, O2:air, 100% O2 during O2:N2O anaesthesia. Ventilatory parameters did not change with variation in PLMA cuff pressure. Post-operative sore throat had no correlation with cuff pressure. [ABSTRACT FROM AUTHOR]

Background and Aims: Studies have demonstrated minimal hemodynamic variation and postoperative complications with ProSeal laryngeal mask airway (PLMA) compared to endotracheal tube (ETT). Hence, a study was conducted to compare the ventilatory parameters and airway dynamics required to maintain normocarbia and stable hemodynamics with PLMA and ETT. Material and Methods: A prospective, randomized, single blinded study was conducted on 60 patients aged 20-40 years of American society of anesthesiologists class I and II, divided into Group PLMA and Group ETT. Standard anesthesia protocol was instituted. Group PLMA received PLMA sizes as per manufacturer's recommendations and group ETT received appropriate sized cuffed ETT. Patients were initially ventilated at 14 bpm, I:E ratio 1:2, tidal volume (Vt) 6 ml/kg and later adjusted to maintain end tidal carbon dioxide (EtCO2) between 35 and 40 mmHg. Peak airway pressure (Ppeak), compliance (Compl.), Vt, airway resistance (Raw), hemodynamic parameters, oxygen saturation (SpO2) and EtCO2 were recorded throughout surgery. Postoperative complications if any, were noted. Results: Demographic parameters, Raw, EtCO2, SpO2 were comparable between groups. Ppeak was lower and Vt needed to maintain EtCO2 of 35-40 mmHg was lesser in Group PLMA. Compl was low for 5 min after insertion of PLMA. Heart rate was significantly reduced at 1 min post insertion; blood pressures were significantly lower upto 2 min after insertion and post removal in group PLMA. Incidence of cough was significantly lower in group PLMA. Conclusion: ProSeal laryngeal mask airway maintains adequate ventilation at lower Vts and minimal peak pressures, has lesser hemodynamic variations and lower incidence of postoperative cough compared to ETT. [ABSTRACT FROM AUTHOR]

To elucidate key factors of host susceptibility to air pollution, healthy and cardiovascular (CV)-compromised rats were exposed to air or ozone (O3) at 0.25, 0.5, or 1.0 ppm for 4 h. We hypothesized that rat strains with the least cardiac reserve would be most prone to develop significant health effects. Using flow whole body plethysmography (FWBP), ventilatory responses in healthy 3-month-old male rats [i.e. Wistar–Kyoto (WKY), Wistar (WIS), and Sprague–Dawley (SD) strains] were compared with hypertensive [i.e. spontaneously hypertensive (SH), fawn-hooded-hypertensive (FHH), and SH-stroke-prone (SHSP)] strains and obese [i.e. SH-heart failure-prone (SHHF) and JCR:LA-cp, atherosclerosis-prone (JCR)] strains. SH were slower to acclimate to the FWBP chambers. At 0-h post-air-exposure, SHSP and SHHF exhibited hyperpnea, indicative of cardiopulmonary insufficiency. At 0-h-post-O3, all but one strain showed significant concentration-dependent decreases in minute volume [MV = tidal volume (TV) × breathing frequency]. Comparing air with 1.0 ppm responses, MV declined 20–27% in healthy, 21–42% in hypertensive, and 33% in JCR rats, but was unchanged in SHHF rats. Penh increased significantly in all strains, with disproportionate increases in “responder” WKY and FHH strains. By 20 h, most changes had resolved, although Penh remained elevated in WKY, SH, and SHSP. Based on theeffectivedose estimates (O3 ppm × h × MV), the most CV-compromised (SHSP and SHHF) strains received significantly greater O3lung deposition (25% and 40%, respectively). Data support epidemiologic associations that individuals with cardiopulmonary insufficiency are at greater risk for urban pollutant exposure due, in part, to enhanced lung deposition and exacerbation of hypoxia and pathophysiologic processes of heart failure. [ABSTRACT FROM AUTHOR]

The clothing used during exercise is an important determinant of hyperthermia and cardiorespiratory adjustments. The purpose of this study the indirect effect of two different types of clothing on cardiorespiratory parameters and water body in a continuous exercise was compared. 10 men, mean age 18.3 ± 0.3 years, 68.7 ± 8,9 kg (BM), 178 ± 10,2 cm (Estature) and 23,13 ± 3,4 (BMI). They conducted two continuous aerobic tests of 30-minute tests at the anaerobic threshold, with ligth clothing (shorts and T-shirt) and heavy clothing (pants, T-shirt and camouflage jacket, used by the military). Reviewed basal metabolic rate, lean body mass, corporal water, heart rate, pulomonary ventilation before and after the tests. No differences were found between the parameters studied in relation to light and heavy clothing. Conclusion, the use of pants, jacket and shirt made with cotton fabric in a physical activity lasting 30 minutes at anaerobic threshold intensity at room temperature 22 oC is not a thermal stress to preclude the same. [ABSTRACT FROM AUTHOR]

Abstract: The effects of microcystin on the cardio-respiratory function of Nile tilapia were analyzed 48h after intraperitoneal injection of microcystin-LR (MC-LR – 100μgkg−1 body weight). Exposure to MC-LR induced significant reduction in metabolic rate () and increase in the critical O2 tension (PCO2) in relation to the control group. Gill ventilation () and ventilatory tidal volume (V T) were considerably lower in fish exposed to MC-LR, probably due to an alteration in the homeostatic mechanisms, impairing the regular respiratory response of this species to environmental hypoxia. The ability to maintain the O2 extraction from the ventilatory current (EO2) during severe hypoxia was also significantly reduced in fish exposed to MC-LR exposure. Control fish displayed the characteristic reflex bradycardia in response to hypoxia. However, when compared to the control group, fish exposed to MC-LR presented significantly lower heart rate (f H) in normoxia and in all experimental hypoxic levels, probably due to a direct effect of this toxin on the cardiac tissue. [Copyright &y& Elsevier]

The cardio-respiratory function, oxidative stress and fish antioxidants were analyzed in juvenile Nile tilapia exposed for 96h to a sublethal trichlorfon (TRC-Neguvon®, Bayer) concentration of 0.5mgL¿1. The exposure to TRC induced oxidative stress in the heart, as manifested by the glutathione S-transferase depletion and hydroperoxide elevation, and was the most sensitive organ when compared to the liver and gills, in which the antioxidant mechanisms against TRC exposure were sufficient to remove reactive oxygen species (ROS), preventing the increase of lipid peroxidation. TRC exposure also reduced O2 uptake and increased the critical oxygen tension (PcO2), reducing the species capacity to survive prolonged hypoxic conditions. The heart rate and force contraction were significantly impaired, making the heart the most sensitive organ when exposed to the TRC. [Copyright &y& Elsevier]

There is an urgent need to understand the intracellular mechanisms by which synthetic opioids, such as fentanyl, depress breathing. We used L -NAME (NG-nitro- L -arginine methyl ester), a nitric oxide synthase (NOS) inhibitor, to provide evidence for a role of nitric oxide (NO) and nitrosyl factors, including S-nitrosothiols, in fentanyl-induced suppression of breathing in rats. We measured breathing parameters using unrestrained plethysmography to record the changes produced by bolus administration of fentanyl (25 μg/kg, IV) in male Sprague Dawley rats that were pretreated with vehicle (saline), L -NAME (50 μmol/kg, IV) or the inactive D -isomer, D -NAME (50 μmol/kg, IV), 15 min previously. L -NAME produced a series of ventilatory changes that included (i) sustained elevations in breathing frequency, due to the reductions in the durations of inspiration and expiration, (ii) sustained elevations in minute ventilation, accompanied by minimal changes in tidal volume, and (iii) increases in inspiratory drive and expiratory drive, and peak inspiratory flow and peak expiratory flow. Subsequent administration of fentanyl in rats pretreated with vehicle produced negative effects on breathing, including decreases in frequency, tidal volume and therefore minute ventilation. Fentanyl elicited markedly different responses in rats that were pretreated with L -NAME, and conclusively, the negative effects of fentanyl were augmented by the NOS inhibitor. D -NAME did not alter ventilatory parameters or modulate the effects of fentanyl on breathing. Our study fully characterized the effects of L -NAME on ventilation in rats and is the first to suggest a potential role of nitrosyl factors in the ventilatory responses to fentanyl. Our data shows that nitrosyl factors reduce the expression of fentanyl-induced changes in ventilation. Panel A: Fentanyl-activated μ-ORs recruit histidine triad nucleotide-binding protein 1 (HINT1) while simultaneously activating neuronal NOS (nNOS). HINT1 then recruits nNOS to the μ-OR-HINT1 complex [64,66]. nNOS produces small molecule S-nitrosothiols and S-nitrosylated proteins which serve to protect against fentanyl-induced respiratory depression. Panel B: Fentanyl-activated μ-ORs recruit HINT1 but nNOS is inhibited by L -NAME and nNOS cannot produce small molecule S-nitrosothiols and S-nitrosylated proteins. Blockade of nNOS has a number of effects including preventing the formation of the μ-OR-NMDA (N-methyl- D -aspartate) receptor super complex, which is a possible mechanism for the potentiation of fentanyl-induced respiratory depression in the absence of NOS activity [65,69]. [Display omitted] [ABSTRACT FROM AUTHOR]

The "anaerobic threshold" concept has been the most polemic and controversial issue of recent exercise physiology history. Great part of this controversy is related to the original proposed mechanisms to explain muscle lactate synthesis and cause-effect association between metabolic acidosis and ventilatory adaptations. The aim of this review is to examine, in agreement with actual theories, the metabolic adaptations that cause the anaerobic threshold phenomenon and some methods used in its detection. [ABSTRACT FROM AUTHOR]

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The case records of 59 patients with congenital diaphragmatic hernia (CDH) who presented between 1984 and 1997 were studied retrospectively. Included in the study were infants born with CDH who required respiratory support within the first 6 h of life. Twenty-three were excluded from the study for various reasons; 36 were enrolled in the study; the male-to-female ratio was 18:18. Twenty-nine hernias were left-sided and 7 were right-sided. All patients were ventilated using conventional techniques. Arterial blood gases were measured on average 1.76 h following admission and the initial period of resuscitation (range 1–4 h). Three formulae were applied in an attempt to predict outcome: ventilation index against PCO2, alveolar-arterial oxygen gradient, and a newly derived formula from this institution (Red Cross formula) that comprises respiratory rate × PCO2× FiO2× mean airway pressure/PaO2× 6000. Seventeen patients (47.2%) survived and 19 died (52.8%); 21 became stable enough to undergo surgery. The average time from presentation until surgery was 1.98 days (range 6 h to 4 days). The Red Cross formula, with a 100% predictive value for mortality, 85% predictive value for survival, and an overall predictive value of 91.6%, appeared to be superior to the other formulae studied. The availability of a highly accurate predictive formula may facilitate management of this frequently lethal disease. [ABSTRACT FROM AUTHOR]

Blood gas analysis can be used to reliably predict outcome in infants with congenital diaphragmatic hernia (CDH) both before and after surgical repair, providing these values are indexed to some measurement of alveolar ventilation. Until recently there has been difficulty in interpreting some of the published data because of differing sampling sites and the fact that ventilatory parameters, which have major influences on all blood gas values in this anomaly, were not included. Application of this information enables us to identify infants with similar degrees of severity of CDH in order to evaluate the efficacy of novel forms of therapy and to determine whether they represent a genuine advance in management where more conventional forms of treatment have failed. [ABSTRACT FROM AUTHOR]

Background: The SERVE-HF study has raised questions concerning the higher mortality under adaptive servoventilation. The ventilatory mode was discussed as a possible aggravating factor., Objectives: We wondered if the data recorded by the adaptive servo-ventilation (ASV)-devices in heart failure patients with CSA-CSR ± OSA are different in terms of respiratory parameters and therapeutic pressures compared to patients with CPAP-resistant/emergent-CSA with normal BNP/NT-pro-BNP., Methods: Patients were included, if ASV had normalized respiratory disturbance index in the first night of application and after at least 6 weeks. ASV-device data were analyzed in terms of respiratory rate (RR), min ventilation (MV), endexpiratory (EEP), peak inspiratory pressure (Ppeak) and median pressure., Results: Compared to CPAP-resistant/emergent-CSA with normal BNP/NT-pro-BNP (n = 25), CSA-CSR- (n = 13) CSA-CSR+OSA-patients (n = 32) with elevated BNP/NT-pro-BNP had higher RR (p < 0.01) in the first night of ASV therapy and during follow-up (15.3 ± 1.3 vs. 17.3 ± 2.4/min) with similar MV (6.5 ± 1.3 vs. 6.6 ± 1.3 L), resulting in significantly lower tidal volumes. EEP (5.6 ± 1.1 vs. 5.5 ± 1.1 hPa), Pmedian and Ppeak (9.8 ± 1.5 vs. 9.7 ± 1.2 hPa) were comparable. Ventilatory parameters were not different between LVEF < 40, 40-49, and ≥50%, neither within the whole group nor the group of CSA-CSR ± OSA and heart failure., Conclusion: Patients with heart failure and CSA-CSR ± OSA have higher RRs but similar MV under ASV-therapy than patients with CSA and normal BNP. This indicates higher dead space ventilation. EF was not found to have an influence on the ventilatory parameters., (© 2018 S. Karger AG, Basel.)