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Pregnancy is associated with major changes in hormonal status, anatomy and physiology involving all systems of a human organism. This narrative review focuses on the most recent data concerning lung function changes during healthy pregnancy. The major findings are as follows: pregnancy is associated with a reduction in static lung volumes reaching 20% of residual functional capacity; it is also associated with chronic alveolar hyperventilation; lastly, it is not associated with significant changes in variables measured by spirometry such as vital capacity, forced expiratory volume in one second and peak expiratory flow, or airway resistance., (Copyright © 2024 SPLF. Published by Elsevier Masson SAS. All rights reserved.)

Manual ventilation, most commonly with a bag-valve mask, is a form of short-term ventilation used during resuscitative efforts in emergent and out-of-hospital scenarios. However, compared to mechanical ventilation, manual ventilation is an operator-dependent skill that is less well controlled and is highly subject to providing inappropriate ventilation to the patient. This article first reviews recent manual ventilation guidelines set forth by the American Heart Association and European Resuscitation Council for providing appropriate manual ventilation parameters (e.g., tidal volume and respiratory rate) in different patient populations in the setting of cardiopulmonary resuscitation. There is then a brief review of clinical and manikin-based studies that demonstrate healthcare providers routinely hyperventilate patients during manual ventilation, particularly in emergent scenarios. A discussion of the possible mechanisms of injury that can occur during inappropriate manual hyperventilation follows, including adverse hemodynamic alterations and lung injury such as acute barotrauma, gastric regurgitation and aspiration, and the possibility of a subacute, inflammatory-driven lung injury. Together, these injurious processes are described as manual-ventilation-induced lung injury (MVILI). This review concludes with a discussion that highlights recent progress in techniques and technologies for minimizing manual hyperventilation and MVILI, with a particular emphasis on tidal-volume feedback devices.

Hyperventilation is common in pulmonary arterial hypertension and may be related to autonomic imbalance. Patients underwent exercise testing and hyperoxic breathing before and after bisoprolol treatment. We found that neither beta blocker treatment nor hyperoxic breathing in patients reduced hyperventilation at rest and during exercise, although it reduced heart rate.

This document is a comment on a correspondence article regarding the management of acute respiratory distress syndrome (ARDS) and the use of negative pressure ventilation (NPV). The authors agree that NPV is often overlooked in ARDS management, but they argue that ventilatory induced lung injury (VILI) is primarily caused by excessive strain on the lungs, rather than the positive or negative airway pressure itself. They explain that the risk of VILI depends on the ratio between lung elastance and total respiratory system elastance, and that excessive negative pleural pressure can have pulmonary and hemodynamic consequences. The authors remain skeptical about the effectiveness of negative pressure ventilation and suggest that extracorporeal support may be necessary to mitigate injury risks. [Extracted from the article]

This article discusses the use of exercise tests to assess the physiological reserve and operability of patients before lung cancer resection. The study validates the use of peakVO2, a measure of maximal oxygen uptake, and the minute ventilation to carbon dioxide output (VE/VCO2) slope as predictors of mortality and cardiopulmonary complications following surgery. The article suggests that incorporating the VE/VCO2 slope into risk stratification algorithms could help identify high-risk patients who may benefit from alternative treatment options. However, further research is needed to determine the relationship between peakVO2 and the VE/VCO2 slope and to standardize the analysis of the VE/VCO2 relationship. [Extracted from the article]

Background: Periodic breathing (PB) is a cyclical breathing pattern composed of alternating periods of hyperventilation (hyperpnea, HP) and central apnea (CA). Differences in PB phenotypes mainly reside in HP length. Given that respiration modulates muscle sympathetic nerve activity (MSNA), which decreases during HP and increases during CA, the net effects of PB on MSNA may critically depend on HP length. Objectives: We hypothesized that PB with shorter periods of HP is associated with increased MSNA and decreased heart rate variability. Methods: 10 healthy participants underwent microelectrode recordings of MSNA from the common peroneal nerve along with non-invasive recording of HRV, blood pressure and respiration. Following a 10-min period of tidal breathing, participants were asked to simulate PB for 3 min following a computed respiratory waveform that emulated two PB patterns, comprising a constant CA of 20 s duration and HP of two different lengths: short (20 s) vs long (40 s). Results: Compared to (3 min of) normal breathing, simulated PB with short HP resulted in a marked increase in mean and maximum MSNA amplitude (from 3.2 ± 0.8 to 3.4 ± 0.8 µV, p = 0.04; from 3.8 ± 0.9 to 4.3 ± 1.1 µV, p = 0.04, respectively). This was paralleled by an increase in LF/HF ratio of heart rate variability (from 0.9 ± 0.5 to 2.0 ± 1.3; p = 0.04). In contrast, MSNA response to simulated PB with long HP did not change as compared to normal breathing. Single CA events consistently resulted in markedly increased MSNA (all p < 0.01) when compared to the preceding HPs, while periods of HP, regardless of duration, decreased MSNA (p < 0.05) when compared to normal breathing Conclusion: Overall, the net effects of PB in healthy subjects over time on MSNA are dependent on the relative duration of HP: increased sympathetic outflow is seen during PB with a short but not with a long period of HP. [ABSTRACT FROM AUTHOR]

Cardiac disease is the leading cause of morbidity and mortality in pregnant women. There is a wide range of diagnoses ranging from congenital heart disease (CHD) to valvular heart disease. Obstetricians and anaesthesiologists need great understanding of physiology and pharmacological therapy of these parturients. ///Physiological changes in pregnancy occur in the first trimester and peak at term. Parturients respond differently to physiological changes. Cardiovascular system changes include a fall in systemic vascular resistance (SVR), increased cardiac output (CO) and plasma volume. Oxygen consumption, metabolic rate, oxygen demand, minute ventilation and tidal volume are increased in pregnancy. Anaemia of pregnancy, fall in platelet count and hypercoagulability also occur. Serum creatinine and urea are decreased. ///General principles and management of pregnant cardiac patients include optimising the mother, managing complications, analgesia and haemodynamic monitoring. Vaginal delivery and regional analgesia is generally recommended. Caesarean section (CS) can be safely done with segmental epidural anaesthesia. ///Rheumatic heart disease (RHD) is the most common cause of valvular disease in pregnancy and mitral stenosis is the dominant (90%) lesion. Symptoms include orthopnoea, exertional dyspnoea or pulmonary oedema. The anaesthetic goals for mitral and aortic stenosis are to avoid tachycardia and decrease in SVR, maintain sinus rhythm and optimise preload. Labour, vaginal and CS delivery anaesthesia may be accomplished with segmental epidural. Regurgitant lesions are well-tolerated in pregnancy, and anaesthetic goals are to avoid increase in SVR and bradycardia, and prevention of myocardial depression. ///CHD is becoming a common disease in pregnancy, with acyanotic lesions well-tolerated in pregnancy compared to cyanotic lesions. Acyanotic lesions' anaesthetic goals for labour, delivery and CS are to avoid intravenous injection of air, hypoxia, hypercarbia and decrease in SVR. Regional anaesthesia must be used with caution in Tetralogy of Fallot (TOF) patients, however it is deemed safe in Eisenmenger syndrome. ///Pulmonary hypertension (PHT) in pregnancy carries a very high risk of mortality (5-25%) and pregnancy should be discouraged, however epidural anaesthesia is recommended in these patients. Segmental epidural is also recommended for patients with postpartum cardiomyopathy. Pregnant women presenting for emergency cardiac surgery should not be postponed due to pregnancy. [ABSTRACT FROM AUTHOR]

BACKGROUND: Excessive ventilation at rates of 30 breaths per minute (bpm) or more during cardiopulmonary resuscitation (CPR) decreases venous return and coronary perfusion pressure, leading to lower survival rates in animal models. A review of our institution's pediatric CPR data revealed that patients frequently received excessive ventilation. METHODS: We designed a multifaceted quality improvement program to decrease the incidence of clinically significant hyperventilation ($30 bpm) during pediatric CPR. The program consisted of provider education, CPR ventilation tools (ventilation reminder cards, ventilation metronome), and individual CPR team member feedback. CPR events were reviewed pre- and postintervention. The first 10 minutes of each CPR event were divided into 20 second epochs, and the ventilation rate in each epoch was measured via end-tidal carbon dioxide waveform. Individual epochs were classified as within the target ventilation range (<30 bpm) or clinically significant hyperventilation (≥30 bpm). The proportion of epochs with clinically significant hyperventilation, as well as median ventilation rates, were analyzed in the pre- and postintervention periods. RESULTS: In the preintervention period (37 events, 699 epochs), 51% of CPR epochs had ventilation rates ≥30 bpm. In the postintervention period (24 events, 426 epochs), the proportion of CPR epochs with clinically significant hyperventilation decreased to 29% (P < .001). Median respiratory rates decreased from 30 bpm (interquartile range 21-36) preintervention to 21 bpm (interquartile range 12-30) postintervention (P < .001). CONCLUSIONS: A quality improvement initiative grounded in improved provider education, CPR team member feedback, and tools focused on CPR ventilation rates was effective at reducing rates of clinically significant hyperventilation during pediatric CPR. [ABSTRACT FROM AUTHOR]

Joubert syndrome (JS) is a rare ciliopathy characterized by neurodevelopmental delay and irregular breathing patterns. Here we present a patient with JS, who was misdiagnosed as having epilepsy. A five year-old girl with JS was referred due to excessive daytime sleepiness. She was diagnosed as having apneic seizures, and given antiseizure medications with no benefit. Apneas were present during wakefulness lasting for more than one minute, with sudden myoclonic jerks characterized by the extension of the body and the flexion of the limbs at the resume of respiration with paradoxical breathing, hyperventilation and tachypnea. A full-night polysomnography (PSG) revealed pediatric obstructive and central sleep apnea syndromes. The patient was effectively treated by adaptive servo ventilation therapy. Respiratory control disturbances are commonly encountered in the children with JS. Although routine electroencephalography may be helpful in differentiation of the apneas of epileptic origin, polygraphic recordings and/or PSG better delineate the pathophysiology. [ABSTRACT FROM AUTHOR]

(2) When MT filled out the Depression, Anxiety, and Stress Scales (DASS) with her mother - and scored 48 of the possible score of 63 (very high) - her mother understood that MT perceived the cumulative stressors that she had experienced as very substantial.[2] (3) MT's parents - and the team - realized that MT's recovery process would take longer than was typical for young children and that they needed to prepare for the long haul. Stephen Porges, PhD As a consultant in this Clinical Challenge, I see my role as twofold: (1) to explain the core mechanisms that would manifest in a subset of symptoms experienced by MT, and (2) to explain how modulated vocalizations/music would function as a neuromodulator to optimize neurophysiological regulation and reduce MT's symptoms. It is important to note, however, that analgesia is achieved at lower doses than those needed to address depression[83] and that tricyclics are ineffective for depression in youth.[84] As was evident in MT's case, patients with functional seizures often present in a high state of physiological arousal.[85] Given that alpha agonist medications, such as the guanfacine used with MT, often decrease sympathetic arousal, they may be helpful with FND symptoms.[[86]] Anticonvulsants are also often prescribed for patients with FND. As expected, MT's symptoms improved when parents and teachers minimized attention to her symptoms The multidisciplinary approach involves intervening in patients' illness beliefs, reducing maladaptive behaviors,[78] minimizing and normalizing functional symptoms, addressing problematic family dynamics, and emphasizing the importance of restoring functioning, along with psychoeducation.[79] This approach was paramount in achieving a positive outcome in MT's case. [Extracted from the article]

Background Routine electroencephalography (EEG) is a widely used test in children for the evaluation of many neurological conditions. It is specifically important in the diagnosis of epilepsy and the differentiation of epilepsy from nonepileptic events. Aim This study aimed to evaluate the current situation of EEG recording at Alexandria University Children's Hospital. Patients and methods All patients who had a routine EEG recording during a period of 6 months were included in the study. Review of the records was done including personal data, place and indication of referral, and initial diagnosis. EEG data included condition during recording, activation procedures, EEG interpretation regarding background activity, presence or absence of epileptiform activity, type and origin of epileptiform discharges, and the final yield of EEG. Results The study included 570 children, comprising 336 males and 234 females, with a mean age of 5.5±4.1 years. The main indication for referral was epilepsy in 69.8%. Most of the cases (83.3%) had an awake recording. Photic stimulation and hyperventilation were done in 93.3 and 31.9%, respectively, and abnormal response to hyperventilation was observed in 9.9% of them. Ictal recording was done in 22 (3.8%) cases. Abnormal epileptiform discharges were detected in 173 (30.4%) of the studied children; of them, 162 cases were initially referred for established epilepsy and 11 cases for other reasons. The abnormality was generalized in 53.8% and focal in 46.2% of the cases. The commonest types of epileptiform discharges were spikes (65.9%) followed by spike-and-wave complexes (56.1%). Hypsarrhythmia, 3-Hz spike-and-wave complexes, and nonconvulsive status epilepticus were detected in 12.7, 10.4, and 2.9%, respectively. Phase reversal, sharp waves, and polyspikes were detected in 15.6, 5.2, and 2.3%, respectively. Conclusion Routine EEG is a valuable test for evaluation of seizures and epilepsy. Specific abnormal epileptiform discharges are diagnostic for certain epileptic syndromes. EEG finding may be normal in children with epilepsy and should be interpreted in the context of the clinical settings. [ABSTRACT FROM AUTHOR]

Introduction: Moyamoya syndrome associated with Williams syndrome is very rare but has been reported to have severe outcomes. Here, we reported a case of Williams syndrome with moyamoya syndrome that was confirmed by the presence of an RNF213 mutation. Case Presentation: A 6-year-old boy with Williams syndrome presented with right hemiparesis induced by hyperventilation. Magnetic resonance angiography and cerebral angiography showed severe stenosis of the bilateral internal carotid arteries and development of moyamoya vessels. Genetic analysis identified a heterozygous c.14576G>A (p.R4859K) mutation in RNF213. Moyamoya syndrome was diagnosed, and bilateral indirect revascularization surgery was conducted without complications and with a good postoperative course. In moyamoya syndrome associated with Williams syndrome, adequate perioperative management of both the moyamoya arteries and the cardiovascular abnormalities is important to prevent complications. Conclusion: This was the first report on a case in which moyamoya syndrome associated with Williams syndrome was confirmed by the presence of a heterozygous RNF213 mutation. Similar to the workup of moyamoya disease, confirmation of RNF213 mutation in Williams syndrome may be useful in predicting the development of moyamoya syndrome that can lead to severe complications. [ABSTRACT FROM AUTHOR]

Autoresuscitation, also referred to as Lazarus phenomenon, is a rare occurrence whereby a patient may experience restoration of spontaneous circulation and signs of life after a diagnosis of "death" following unsuccessful cardiopulmonary resuscitation. "Found alive after declared dead" has often appeared as sensational news on print, electronic, and social media, and the medical fraternity falls prey to media trials and court enquiry, but this rare phenomenon remains underreported in the medical literature. In this article, we review the reports of Lazarus phenomenon in the medical literature and discuss possible explanations to throw some light on the medicolegal and social implications of this condition. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Physiological episodes are an issue in military aviation. Some non-pressure-related in-flight symptoms are proved to be due to hyperventilation rather than hypoxia. The aim of this study was to validate a new training method provoking hyperventilation during normobaric hypoxia (NH) training in an F/A-18 Hornet simulator. METHODS: In a double-blind setting, 26 fighter pilots from the Finnish Air Force performed 2 setups in a WTSAT simulator in randomized order with full flight gear. Without the pilot's knowledge, 6% O2 in nitrogen or 6% O2 + 4% CO2 in nitrogen was turned on. Ventilation (VE) was measured before, during, and after hypoxia. Spo2 and ECG were monitored and symptoms documented. The subjects performed a tactical identification flight until they recognized symptoms of hypoxia. Thereafter, they performed hypoxia emergency procedures with 100% O2 and returned to the base with a GPS malfunction and executed an instrument landing system (ILS) approach with the waterline HUD mode evaluated by the flight instructor on a scale of 1 to 5. RESULTS: Ventilation increased during normobaric hypoxia (NH) from 12 L · min−1 to 19 L · min−1 at Spo2 75% with 6% O2, and from 12 L · min−1 to 26 L · min−1 at Spo2 77% with 6% O2 + 4% CO2. ILS flight performance was similar 10 min after combined hyperventilation and hypoxia (3.1 with 6% O2 + 4% CO2 and 3.2 with 6% O2). No adverse effects were reported during the 24-h follow-up. DISCUSSION: Hyperventilation-provoking normobaric hypoxia training is a new and well-tolerated method to meet NATO Standardization Agreement hypoxia training requirements. [ABSTRACT FROM AUTHOR]

In patients with suspected acute coronary syndrome high-sensitivity cardiac tropnonin T is used for rapid patient triage. Some acute coronary syndrome patients assigned to the observe zone based on high-sensitivity cardiac troponin T after 1 h require further diagnostic testing. Fast-strain encoded CMR imaging with breathing maneuvers may accelerate diagnostic work-up and identify patients suffering from acute coronary syndrome. Patients presenting with acute chest pain (high-sensitivity cardiac troponin T level 5–52 ng/L) were prospectively enrolled (consecutive sampling, time of recruitment: 09/18–06/19). Fast-strain-encoded imaging was performed within the 1-h timeframe (0 h/1 h algorithm) prior to 2nd high-sensitivity troponin T lab results. Images were acquired at rest as well as after 1-min of hyperventilation followed by a short breath-hold. In 108 patients (59 male; mean age: 57 ± 17y) the mean study time was 17 ± 3 min. An abnormal strain response after the breathing maneuver (persistent/increased/new onset of increased strain rates) correctly identified all 17 patients with a high-sensitivity troponin T dynamic (0 h/1 h algorithm) and explanatory significant coronary lesions, while in 86 patients without serologic or angiographic evidence for severe coronary artery disease the strain response was normal (sensitivity 100%, specificity 94.5%; 5 false positive results). The number of dysfunctional segments (strain > − 10%) proved to be a quantifiable marker for identifying patients with acute coronary syndrome. In patients with suspected acute coronary syndrome and inconclusive initial high-sensitivity troponin T, fast-strain-encoded imaging with a breathing maneuver may safely and rapidly identify patients with acute coronary syndrome, without the need for vasodilators, stress, or contrast agents. [ABSTRACT FROM AUTHOR]

Asthma is frequently accompanied by dysfunctional breathing of which hyperventilation has been recognized as a subtype. The prevalence of hyperventilation in stable asthma has been scantily studied using blood gas analysis. Hence, a reliable estimate of its prevalence is lacking. It is unknown whether the Nijmegen Questionnaire (NQ) is a useful screening tool for hyperventilation in asthma. Therefore, the primary aim of this study was to determine the prevalence of hyperventilation in a large sample of patients with asthma in a stable state of disease. Secondary aims were to compare the clinical characteristics between patients with and without hyperventilation, and, to examine the concurrent validity of the NQ to detect hypocapnia in patients with asthma. A real-world, observational, multicenter study was conducted. Capillary blood gas analysis was performed in adults with a confirmed diagnosis of stable asthma. A subset of patients completed the NQ. A blood gas analysis was obtained in 1006 patients. In 17% of the patients an acute hyperventilation was found, and in another 23% a chronic hyperventilation was uncovered. Patients with a chronic hyperventilation blood gas were more often female, were younger and had a better spirometric outcomes. The NQ appeared not to correlate with PCO2. Hyperventilation is common in patients with stable asthma. Chronic hyperventilation is more often found in females of younger age and with the best spirometric outcomes compared to patients without hyperventilation. The NQ is not a suitable screening tool for the presence of hyperventilation in stable asthmatics. [ABSTRACT FROM AUTHOR]

Humans hyperventilate under heat and cold strain. This hyperventilatory response has detrimental consequences including acid–base dysregulation, dyspnoea, decreased cerebral blood flow and accelerated brain heating. The ventilatory response to hypoxia is exaggerated under whole-body heating and cooling, indicating that altered carotid body function might contribute to thermally mediated hyperventilation. To address whether the carotid body might contribute to heat- and cold-induced hyperventilation, we indirectly measured carotid body tonic activity via hyperoxia, and carotid body sensitivity via hypoxia, under graded heat and cold strain in 13 healthy participants in a repeated-measures design. We hypothesised that carotid body tonic activity and sensitivity would be elevated in a dose-dependent manner under graded heat and cold strain, thereby supporting its role in driving thermally mediated hyperventilation. Carotid body tonic activity was increased in a dose-dependent manner with heating, reaching 175% above baseline (P < 0.0005), and carotid body suppression with hyperoxia removed all of the heat-induced increase in ventilation (P = 0.9297). Core cooling increased carotid body activity by up to 250% (P < 0.0001), but maximal values were reached with mild cooling and thereafter plateaued. Carotid body sensitivity to hypoxia was profoundly increased by up to 180% with heat stress (P = 0.0097), whereas cooling had no detectable effect on hypoxic sensitivity. In summary, cold stress increased carotid body tonic activity and this effect was saturated with mild cooling, whereas heating had clear dose-dependent effects on carotid body tonic activity and sensitivity. These dose-dependent effects with heat strain indicate that the carotid body probably plays a primary role in driving heat-induced hyperventilation. [ABSTRACT FROM AUTHOR]

Permissive hypercapnia ([9]) and, in some cases, mild, graded permissive hypoxemia ([10]) appear to be well-tolerated alternatives to otherwise noxious intrusions, such as ventilation with high levels of airway driving pressure and inspired oxygen. Keywords: critical illness; homeostatic control; homeostasis EN critical illness homeostatic control homeostasis 1268 1271 4 07/18/22 20220801 NES 220801 THE CONCEPT AND RANGE OF HOMEOSTASIS A wide range of physical demands characterizes the activities of daily life. Neither patient nor physician may know all the relevant particulars - patient self-induced lung injury as well as ventilator-induced lung injury (VILI) are equally possible at every stage ([2], [3]). The appropriate hierarchy of signals may be disrupted by acute disease or sensory inputs to the controller may be out of balance, and it is almost certain that the "vulnerability" of lung tissue is not "hard wired" into the native control system. [Extracted from the article]

Aim: To analyze the impact of obesity on cardiopulmonary response to exercise in people with chronic post-COVID-19 syndrome. Patients & methods: Consecutive subjects with chronic post-COVID syndrome 6 months after nonsevere acute infection were included. All patients received a complete clinical evaluation, lung function tests and cardiopulmonary exercise testing. A total of 51 consecutive patients diagnosed with chronic post-COVID-19 were enrolled in this study. Results: More than half of patients with chronic post-COVID-19 had a significant alteration in aerobic exercise capacity (VO2peak) 6 months after hospital discharge. Obese long-COVID-19 patients also displayed a marked reduction of oxygen pulse (O2pulse). Conclusion: Obese patients were more prone to have pathological pulmonary limitation and pulmonary gas exchange impairment to exercise compared with nonobese COVID-19 patients. [ABSTRACT FROM AUTHOR]

Cerebral blood flow (CBF) can be altered by a change in partial pressure of arterial CO2 (PCO2), being reduced during hyperventilation (HPV). Critical closing pressure (CrCP) and resistance area product (RAP) are parameters that can be studied to understand this change, but their dynamic response has not been investigated during paced HPV (PHPV). Seventy-five participants had recordings at rest and during PHPV. Blood pressure (BP) (Finometer), bilateral CBF velocity (CBFV) (transcranial Doppler), end-tidal CO2 (capnography), and heart rate (HR) were recorded continuously. Subcomponent analysis (SCA) and time-varying CrCP, RAP, and dynamic cerebral autoregulation (autoregulation index, ARI) were estimated by comparing PHPV with poikilocapnia. PHPV caused a change in CBFV (P < 0.01), EtCO2, (P < 0.01), HR (P < 0.001), and RAP (P < 0.01). SCA demonstrated RAP was the main parameter explaining the changes in CBFV due to PHPV. The time-varying step responses for CBFV and RAP during PHPV demonstrated considerable nonstationarity compared with poikilocapnia (P < 0.00001). Although time-varying ARI was temporarily depressed, after 60 s of PHPV it was significantly higher (6.81 ± 1.88) (P < 0.0001) than in poikilocapnia (5.08 ± 1.86). The mean plateau of the RAP step response was -98.3 ± 58.8% 60 s after the onset of PHPV but -71.7 ± 45.0% for poikilocapnia (P = 0.0026), with no corresponding changes in CrCP (P = 0.6). Further work is needed to assess the role of sex and aging in our findings, and the potential for using RAP and CrCP to improve the sensitivity and specificity of CO2 reactivity studies in cerebrovascular conditions. [ABSTRACT FROM AUTHOR]

Central nervous system oxygen toxicity (CNS-OT) is a complex disorder that presents, initially, as a sequence of cardio-respiratory abnormalities and nonconvulsive signs and symptoms (S/Sx) of brain stem origin that culminate in generalized seizures, loss of consciousness, and postictal cardiogenic pulmonary edema. The risk of CNS-OT and its antecedent "early toxic indications" are what limits the use of hyperbaric oxygen (HBO2) in hyperbaric and undersea medicine. The purpose of this review is to illustrate, based on animal research, how the temporal pattern of abnormal brain stem responses that precedes an "oxtox hit" provides researchers a window into the early neurological events underlying seizure genesis. Specifically, we focus on the phenomenon of hyperoxic hyperventilation, and the medullary neurons presumed to contribute in large part to this paradoxical respiratory response; neurons in the caudal Solitary complex (cSC) of the dorsomedial medulla, including putative CO2 chemoreceptor neurons. The electrophysiological and redox properties of O2-/CO2- sensitive cSC neurons identified in rat brain slice experiments are summarized. Additionally, evidence is summarized that supports the working hypothesis that seizure genesis originates in subcortical areas and involves cardio-respiratory centers and cranial nerve nuclei in the hind brain (brainstem and cerebellum) based on, respectively, the complex temporal pattern of abnormal cardio-respiratory responses and various nonconvulsive S/Sx that precede seizures during exposure to HBO2. [ABSTRACT FROM AUTHOR]

: In military aviation during high-altitude operations, an oxygen or cabin pressure emergency can impair brain function and performance. There are variations in individuals’ physiological responses to low partial pressure of oxygen and hypoxia symptoms can vary from one exposure to another. The aim of this study was to evaluate how normobaric hypoxia (NH) affects pilots’ minute ventilation and 10 min afterwards on Instrument Landing System (ILS) flight performance in Hawk simulator during a tactical flight sortie. Fifteen volunteer fighter pilots from the Finnish Air Force participated in this double blinded, placebo controlled and randomized study. The subjects performed three flights in a tactical Hawk simulator in a randomized order with full flight gear, regulators and masks on. In the middle of the flight without the subjects’ knowledge, 21% (control), 8% or 6% oxygen in nitrogen was turned on. Minute ventilation (VE) was measured before, during NH and after NH. Forehead peripheral oxygen saturation (SpO2), wireless ECG and subjective symptoms were documented. The flights were conducted so that both subjects and flight instructors were blinded to the gas mixture. The pilots performed tactical maneuvers at simulated altitude of 20,000 ft or 26,000 ft until they recognized the symptoms of hypoxia. Thereafter they performed hypoxia emergency procedures with 100% oxygen and returned to base (RTB). During the ILS approach, flight performance was evaluated. The mean VE increased during NH from 12.9 L/min (21% O2 on the control flight) to 17.8 L/min with 8% oxygen (p < 0.01), and to 21.0 L/min with 6% oxygen (p < 0.01). Ten minutes after combined hyperventilation and hypoxia, the ILS flight performance decreased from 4.4 (control flight) to 4.0 with 8% oxygen (p = 0.16) and to 3.2 with 6% oxygen (p < 0.01). A significant correlation (r = -0.472) was found between the subjects’ VE during 6% oxygen exposure and the ILS flight performance. : Hyperventilation during NH has a long-lasting and dose-dependent effect on the pilot’s ILS flight performance, even though the hypoxia emergency procedures are executed 10 min earlier. Hyperventilation leads to body loss of carbon dioxide and hypocapnia which may even worsen the hypoxia hangover. [ABSTRACT FROM AUTHOR]

Background: There is increasing evidence that inflammation plays a role in the pathogenesis of aneurysmal subarachnoid hemorrhage (aSAH) and in the development of delayed cerebral ischemia (DCI). However, the assessment and interpretation of classically defined inflammatory parameters is difficult in aSAH patients. The objective of this study was to investigate the relationship between easily assessable findings (hyperventilation, fever, white blood cell count (WBC), and C-reactive protein (CRP)) and the occurrence of DCI and unfavorable neurological outcome at discharge in aSAH patients. Methods: Retrospective analysis of prospectively collected data from a single center cohort. We evaluated the potential of clinical signs of inflammation (hyperventilation, fever) and simple inflammatory laboratory parameters CRP and WBC to predict unfavorable outcomes at discharge and DCI in a multivariate analysis. A cutoff value for CRP was calculated by Youden's J statistic. Outcome was measured using the modified Rankin score at discharge, with an unfavorable outcome defined as modified Rankin scale (mRS) > 3. Results: We included 97 consecutive aSAH patients (63 females, 34 males, mean age 58 years) in the analysis. Twenty-one (22%) had major disability or died by the time of hospital discharge. Among inflammatory parameters, CRP over 100 mg/dl on day 2 was an independent predictor for worse neurological outcome at discharge. The average C-reactive protein level in the first 14 days was higher in patients with a worse neurological outcome (96.6, SD 48.3 vs 56.3 mg/dl, SD 28.6) in the first 14 days after aSAH. C-reactive protein on day 2 was an indicator of worse neurological outcome. No inflammatory parameter was an independent predictor of DCI. After multivariate adjustment, DCI, increased age, and more than 1 day of mechanical ventilation were significant predictors of worse neurological outcome. Conclusions: Early elevated CRP levels were a significant predictor of worse neurological outcome at hospital discharge and may be a useful marker of later deterioration in aSAH. [ABSTRACT FROM AUTHOR]

Case reports of success in treating catatonia exist for many second-generation antipsychotics.[45] Atypical antipsychotics are hypothesized to treat catatonia via effects on serotonin receptors, which may lead to an increase in dopamine in the prefrontal cortex.[46] In general, we recommend using low-potency agents to minimize the risk of worsening catatonia or inducing a malignant catatonia. Furthermore, in a patient with a recent history of catatonia, aripiprazole may be a reasonable option and may be less likely than other high-potency antipsychotic agents to worsen catatonia.[44] Finally, I would make sure to optimize psychosocial interventions, which could include cognitive-behavioral therapy for psychosis, supported employment, peer support, and family-based interventions. In a survey of 143 U.S. psychiatrists, 38% would rather combine two antipsychotics than use clozapine, and only 45% would use clozapine after two or fewer antipsychotic failures.[9] Efforts should be made to promote clozapine use as soon as possible without unnecessary antipsychotic trials. Keywords: autism, clozapine, schizophrenia, treatment resistance EN autism, clozapine, schizophrenia, treatment resistance 261 269 9 07/14/22 20220701 NES 220701 CASE HISTORY PK was diagnosed with autism spectrum disorder (ASD) at age 4 with the Autism Diagnostic Observation Schedule. [Extracted from the article]

Background: We sought to describe ventilation rates during out-of-hospital cardiac arrest (OHCA) resuscitation and their associations with airway management strategy and outcomes.Methods: We analyzed continuous end-tidal carbon dioxide capnography data from adult OHCA enrolled in the Pragmatic Airway Resuscitation Trial (PART). Using automated signal processing techniques, we determined continuous ventilation rates for consecutive 10-second epochs after airway insertion. We defined hypoventilation as a ventilation rate < 6 breaths/min. We defined hyperventilation as a ventilation rate > 12 breaths/min. We compared differences in total and percentage post-airway hyper- and hypoventilation between airway interventions (laryngeal tube (LT) vs. endotracheal intubation (ETI)). We also determined associations between hypo-/hyperventilation and OHCA outcomes (ROSC, 72-hour survival, hospital survival, hospital survival with favorable neurologic status).Results: Adequate post-airway capnography were available for 1,010 (LT n = 714, ETI n = 296) of 3,004 patients. Median ventilation rates were: LT 8.0 (IQR 6.5-9.6) breaths/min, ETI 7.9 (6.5-9.7) breaths/min. Total duration and percentage of post-airway time with hypoventilation were similar between LT and ETI: median 1.8 vs. 1.7 minutes, p = 0.94; median 10.5% vs. 11.5%, p = 0.60. Total duration and percentage of post-airway time with hyperventilation were similar between LT and ETI: median 0.4 vs. 0.4 minutes, p = 0.91; median 2.1% vs. 1.9%, p = 0.99. Hypo- and hyperventilation exhibited limited associations with OHCA outcomes.Conclusion: In the PART Trial, EMS personnel delivered post-airway ventilations at rates satisfying international guidelines, with only limited hypo- or hyperventilation. Hypo- and hyperventilation durations did not differ between airway management strategy and exhibited uncertain associations with OCHA outcomes. [ABSTRACT FROM AUTHOR]

BACKGROUND: "Epilepsy" is the condition of recurrent, unprovoked seizures. Epilepsy has numerous causes. The worldwide prevalence of active seizure is 4-10 per 1000 population. The prevalence rate in India is 5.59 per 1000. We conducted this study to evaluate clinical and imaging profile in patients presenting with seizures. METHODOLOGY: This was a single centre hospital-based observational cross-sectional conducted in patients with seizures admitted to the department of Medicine. All patients more than 15 years of age with seizures presenting to the department and giving written informed consent were included in the study. During our study period, we got 70 cases satisfying our inclusion and exclusion criteria, so we included all 70 cases in our study. Patients with history of head injury, movement disorders, hyperventilation syndrome, syncope and psychogenic seizures were excluded. OBSERVATIONS: There were 47 males (67.14%), mean age of participants was 52.71 ±14.16 years. 42 patients had no any addictions (60%). Sixty eight cases had GTCS type of seizure (97.14%) and one patient each (1.43%) and Partial and CPS type of seizure. 35 patients had single seizure (50%). Most common feature was past h/o seizure seen in 26 cases (37.14%) followed by headaches in 21 cases (30%). Most common Computed tomography (CT) finding was acute infarct in 7 cases (10%). 48 patients, 68.57% had normal CT findings. MRI findings shows 6 (8.57%) patients with Gliosis, followed by small vessel ischemic changes in 8 (11.43%) patients. While 49 (70%) patients had no abnormality on MRI. Majority of patients had drug Withdrawal Seizure (52.86%), followed by Cerebral-Infarct (14.29%). CONCLUSION: More than half of the patients had single episode of seizure and rest patients had two seizure episodes, very few had three or more seizures. The most common Computed tomography finding was acute infarct (10%) followed by Gliosis (7.14%). Magnetic resonance imaging findings showed most commonly Gliosis, followed by small vessel ischemic changes. About two third of patients had normal Magnetic resonance imaging brain. Commonest etiology was drug Withdrawal Seizure. [ABSTRACT FROM AUTHOR]

Background: Periodic breathing (PB) is a cyclical breathing pattern composed of alternating periods of hyperventilation (hyperpnea, HP) and central apnea (CA). Differences in PB phenotypes mainly reside in HP length. Given that respiration modulates muscle sympathetic nerve activity (MSNA), which decreases during HP and increases during CA, the net effects of PB on MSNA may critically depend on HP length.Objectives: We hypothesized that PB with shorter periods of HP is associated with increased MSNA and decreased heart rate variability.Methods: 10 healthy participants underwent microelectrode recordings of MSNA from the common peroneal nerve along with non-invasive recording of HRV, blood pressure and respiration. Following a 10-min period of tidal breathing, participants were asked to simulate PB for 3 min following a computed respiratory waveform that emulated two PB patterns, comprising a constant CA of 20 s duration and HP of two different lengths: short (20 s) vs long (40 s). Results: Compared to (3 min of) normal breathing, simulated PB with short HP resulted in a marked increase in mean and maximum MSNA amplitude (from 3.2 ± 0.8 to 3.4 ± 0.8 µV, p = 0.04; from 3.8 ± 0.9 to 4.3 ± 1.1 µV, p = 0.04, respectively). This was paralleled by an increase in LF/HF ratio of heart rate variability (from 0.9 ± 0.5 to 2.0 ± 1.3; p = 0.04). In contrast, MSNA response to simulated PB with long HP did not change as compared to normal breathing. Single CA events consistently resulted in markedly increased MSNA (all p < 0.01) when compared to the preceding HPs, while periods of HP, regardless of duration, decreased MSNA (p < 0.05) when compared to normal breathing.Conclusion: Overall, the net effects of PB in healthy subjects over time on MSNA are dependent on the relative duration of HP: increased sympathetic outflow is seen during PB with a short but not with a long period of HP.

Coronavirus disease (COVID-19) is an infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with systemic organ damage in the most severe forms. Long-term complications of SARS-CoV-2 appear to be restricted to severe presentations of COVID-19, but many patients with persistent symptoms have never been hospitalized. Post-acute sequelae of COVID-19 (PASC) represents a heterogeneous group of symptoms characterized by cardiovascular, general, respiratory, and neuropsychiatric sequelae. The pace of evidence acquisition with PASC has been rapid, but the mechanisms behind it are complex and not yet fully understood. In particular, exercise intolerance shares some features with other classic respiratory and cardiac disorders. However, cardiopulmonary exercise testing (CPET) provides a comprehensive assessment and can unmask the pathophysiological mechanism behind exercise intolerance in gray-zone PASC. This mini-review explores the utility of CPET and aims to provide a comprehensive assessment of PASC by summarizing the current evidence.

Introduction: In military aviation during high-altitude operations, an oxygen or cabin pressure emergency can impair brain function and performance. There are variations in individuals’ physiological responses to low partial pressure of oxygen and hypoxia symptoms can vary from one exposure to another. The aim of this study was to evaluate how normobaric hypoxia (NH) affects pilots’ minute ventilation and 10 min afterwards on Instrument Landing System (ILS) flight performance in Hawk simulator during a tactical flight sortie.Methods: Fifteen volunteer fighter pilots from the Finnish Air Force participated in this double blinded, placebo controlled and randomized study. The subjects performed three flights in a tactical Hawk simulator in a randomized order with full flight gear, regulators and masks on. In the middle of the flight without the subjects’ knowledge, 21% (control), 8% or 6% oxygen in nitrogen was turned on. Minute ventilation (VE) was measured before, during NH and after NH. Forehead peripheral oxygen saturation (SpO2), wireless ECG and subjective symptoms were documented. The flights were conducted so that both subjects and flight instructors were blinded to the gas mixture. The pilots performed tactical maneuvers at simulated altitude of 20,000 ft or 26,000 ft until they recognized the symptoms of hypoxia. Thereafter they performed hypoxia emergency procedures with 100% oxygen and returned to base (RTB). During the ILS approach, flight performance was evaluated.Results: The mean VE increased during NH from 12.9 L/min (21% O2 on the control flight) to 17.8 L/min with 8% oxygen (p < 0.01), and to 21.0 L/min with 6% oxygen (p < 0.01). Ten minutes after combined hyperventilation and hypoxia, the ILS flight performance decreased from 4.4 (control flight) to 4.0 with 8% oxygen (p = 0.16) and to 3.2 with 6% oxygen (p < 0.01). A significant correlation (r = -0.472) was found between the subjects’ VE during 6% oxygen exposure and the ILS flight performance.Discussion: Hyperventilation during NH has a long-lasting and dose-dependent effect on the pilot’s ILS flight performance, even though the hypoxia emergency procedures are executed 10 min earlier. Hyperventilation leads to body loss of carbon dioxide and hypocapnia which may even worsen the hypoxia hangover.