Changes In Respiratory Parameters Research Articles

Effects of rapid maxillary expansion on upper airway parameters in OSA children with maxillary restriction: A CBCT study.

Rapid maxillary expansion (RME) has been proposed as an effective treatment for pediatric obstructive sleep apnea (OSA) and maxillary restriction in children. This study aimed to evaluate the effect of RME appliances on the nasomaxillary complex dimensions in children with OSA and maxillary constriction. This prospective longitudinal study included 34 children aged 8-12 years with maxillary restriction and OSA confirmed by polysomnography who had completed RME therapy. The nasomaxillary complex is segmented into the nasal cavity, maxillary sinuses, and nasopharynx. The effect of RME on nasomaxillary complex dimensions was assessed pre and posttreatment using cone-beam computed tomography, analysis, while a second standard overnight polysomnography (PSG) was performed to assess changes in respiratory parameters. Significant improvements were observed, including inferior maxillary dislocation (S-S1 distance and N-ANS), increased anterior and posterior facial height, and a 5.43 events/h reduction in Apnea-Hypopnea Index (p < .001). The nasal cavity volume increased by 2439 (±584) mm3 (p < .001), nasopharynx size increased by 883 (±479) mm3 (p = .008), mid cross-sectional area increased by 31.74 (±14.50) mm2 (p < .001), and the distance between the right and left maxillary sinuses increased by 8.37 (±3.67) mm (p < .001) all exhibited positive changes, with some insignificant variations in volume change (p = .254). RME treatment was found to be effective in improving nasal cavity and nasopharyngeal dimensions, leading to improved respiratory parameters in children with OSA and maxillary constriction. While these results are promising, considerations about the potential long-term benefits of RME on future growth are important. The study provides valuable insights into the efficacy of RME as a treatment option for this pediatric population.

Changes in preBötzinger Complex neuron discharge associated with changes in PCO2 in decerebrate rabbits

Background: Maskrey and Nicol reported a strong increase in minute ventilation with increase in PCO2 (J Physiol 1980, 301: 49-58). We investigated a) whether there was a ceiling to this effect at high CO2 levels and b) whether the change in ventilation was associated with specific changes in respiratory neurons in the preBötzinger complex (preBC). Methods: The study was approved by the local Animal Care Committee and conformed to NIH standards. Adult New Zealand White rabbits (3-4 kg) were anesthetized, tracheotomized, ventilated, decerebrated and vagotomized. Phrenic nerve activity was recorded from the C5 rootlet, time averaged and used to calculate inspiratory (TI) and expiratory durations (TE) and peak phrenic activity (PPA). PPA was normalized to the value at PCO2 50mmHg. Individual neurons were recorded in the functionally identified preBC using multichannel electrodes at increasing CO2 levels. Statistical analysis used the Wilcoxon signed-rank test to determine changes in respiratory parameters between CO2 levels and Friedman RM-ANOVA to determine changes in neuronal discharge frequency (Fn). A generalized linear mixed model was used to determine associations between CO2-dependent changes in TI, TE, PPA, and changes in Fn for different neuron types. p&lt;0.05 indicated a significant difference. Results: In 34 animals, the increase in minute ventilation with increasing PCO2 was due mostly to the change in PPA. The increase in respiratory rate was due mostly to a decrease in TE. There was little increase in respiratory output at PCO2 &gt; 50 mmHg. In 209 neurons, increasing PCO2 increased Fn in inspiratory augmenting (I aug, n= 70, p&lt;0.0001 for CO2 30 vs 40 and 40 vs 50mmHg), I parabolic (I para, n=43, p&lt;0.0001 for CO2 40 vs 50 mmHg), pre-inspiratory (pre-I, n=35, p&lt;0.01 for CO2 30 vs 40 mmHg), and expiratory decrementing (E dec, n=44, p&lt;0.01 for CO2 40 vs 50 mmHg) neurons, but not in I dec (n=8) and non-respiratory modulated (NRM, n=9) neurons. The strongest correlation was found between the changes in phase timing and PPA and Fn in I aug and pre-I neurons. Conclusion: We found a ceiling effect to the increase in respiratory output at PCO2 levels &gt; 50 mmHg. Inspiratory preBC neuron subtypes were more affected by the changes in PCO2. NIH R01HL159546. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

PHYSIO+++: protocol for a pilot randomised controlled trial assessing the feasibility of physiotherapist-led non-invasive ventilation for patients with hypoxaemia following abdominal surgery

IntroductionFew clinical trials have investigated physiotherapy interventions to treat hypoxaemia following abdominal surgery. The objective of this study is to determine the feasibility and safety of conducting a clinical trial...

0975 Severe Central Sleep Apnea After Bilateral Lung Transplantation

Abstract Introduction Central sleep apnea (CSA) is characterized by repetitive disruptions in airflow during sleep due to impaired central respiratory drive. Multiple studies have described an increased incidence of sleep disordered breathing after lung transplantation. However, these studies implicate obstructive sleep apnea as the primary sleep disturbance related to post-transplant weight gain, increased neck circumference, and fluid retention from immunosuppressive therapy. We report an uncommon presentation of new onset severe central predominant sleep apnea in a bilateral lung transplant recipient. Report of case(s) A 61-year-old female with a history of end stage COPD with chronic hypoxic respiratory failure status post bilateral lung transplantation in 2020 presented to sleep medicine clinic with several months of witnessed apneic episodes, excessive daytime sleepiness, morning headaches, and insomnia. Physical exam was notable for an increased body mass index (BMI) of 35 kg/m² from pre-transplant BMI of 29 kg/m². Epworth Sleepiness Scale was 15, compared to 4 prior to transplant. Polysomnogram showed an apnea hypopnea index (AHI) of 94.5 events/hour with central AHI of 54.6, consistent with severe central predominant sleep apnea. Titration on CPAP at 5 cmH2O and 7 cmH2O improved the AHI to 13.3 and 20.3, respectively, with residual central hypopneas. On follow-up, downloaded therapy data revealed a residual AHI of 23.3 on CPAP at 5 cmH2O and 1.5 L/min O2, suggesting the need for a BiPAP/ASV titration study if control remains suboptimal. Conclusion Common etiologies of CSA include heart failure with Cheyne-Stokes respirations, neurologic disease, high altitude, and the use of centrally acting medications. This patient did not have clearly identifiable risk factors. Pre- and post-transplant echocardiograms showed preserved left ventricular function with no regional wall motion abnormalities. She lacks history of neurologic disease or narcotic use, and her current immunosuppressive regimen has not been linked to worsened sleep apnea. Proposed pathogenesis of CSA in lung transplant recipients include abnormalities in respiratory mechanics due to pulmonary denervation and altered chemoreceptor sensitivity. Prompt diagnosis and treatment of sleep disordered breathing is crucial in organ transplant recipients to prevent adverse cardiovascular outcomes. Thus, further investigation is warranted to better characterize the changes in respiratory parameters that occur after lung transplantation. Support (if any)

Preserved Sleep for the Same Level of Respiratory Disturbance in Children with Prader-Willi Syndrome.

Debate remains as to how to balance the use of recombinant human growth hormone (rhGH) as an important treatment in Prader-Willi syndrome (PWS) with its potential role in obstructive sleep apnea. This single-center, retrospective study assessed differences in overnight polysomnography results between children with and without PWS and changes in respiratory parameters before and after the initiation of rhGH treatment in those with PWS. Compared with age-, sex-, and body-mass-index-matched controls (n = 87), children with PWS (n = 29) had longer total sleep time (434 ± 72 vs. 365 ± 116 min; p < 0.01), higher sleep efficiency (86 ± 7 vs. 78 ± 15%; p < 0.05), and lower arousal events (8.1 ± 4.5 vs. 13.0 ± 8.9 events/h; p < 0.05). Mean oxygen saturation was lower in PWS children (94.3 ± 6.0 vs. 96.0 ± 2.0%; p < 0.05), with no other differences in respiratory parameters between groups. Eleven children with PWS (38%) met the criteria for further analyses of the impact of rhGH; polysomnography parameters did not change with treatment. Compared with other children undergoing polysomnography, children with PWS had more favorable markers of sleep continuity and lower oxygen saturation for the same level of respiratory disturbance. rhGH administration was not associated with changes in respiratory parameters in PWS.

Clinical Changes of Respiratory Parameters in Institutionalized Older Adults after a Physiotherapy Program Combining Respiratory and Musculoskeletal Exercises.

Nowadays pulmonary diseases are an increasingly important cause of morbidity and mortality. Diaphragmatic breathing is a controlled-breathing technique that aims to optimize thoracoabdominal movements. The aim of this study was to apply a respiratory and musculoskeletal physiotherapy program in institutionalized older adults and to assess the effects on their pulmonary function tests and oxygen saturation. A randomized double-blind clinical trial was conducted with thirty institutionalized older adults, randomly assigned to a control group (CG), who conducted musculoskeletal exercises; or an experimental group (EG) who, in addition, carried out diaphragmatic breathing, administered for eight weeks, three times/week. Outcomes were pulmonary function variables (forced vital capacity, FVC; forced expired volume at 1 s, FEV1; the FEV1/FVC ratio) and oxygen saturation (SpO2) before and after treatment. Normality of the distributions was tested with Saphiro-Wilk and the pre-post improvement was assessed with a two-sample Mann-Whitney test. Significance level was corrected for multiple comparisons using Benjamini-Hochberg correction (p < 0.04). There was a clinically significant improvement of FVC and FEV1 for the EG. Moreover, the EG showed a statistically significant increase of SpO2 (p = 0.028) after treatment when compared to CG. A physiotherapy program combining breathing and musculoskeletal exercises, improved respiratory parameters in institutionalized older adults.

Effect of two different levels of positive end-expiratory pressure (PEEP) on oxygenation and ventilation during pneumoperitoneum for laparoscopic surgery in children: A randomized controlled study.

Positive end-expiratory pressure (PEEP) is used to attenuate the changes in respiratory parameters because of pneumoperitoneum during laparoscopic (LAP) surgery. As the ideal level of PEEP during LAP in children is not known, this study compared the effect of 5- and 10-cm H2O of PEEP on oxygenation, ventilator, and hemodynamic parameters during pediatric LAP. After obtaining approval from the Institute Ethics Committee and written informed parental consent, 30 American Society of Anesthesiologists (ASA) I and II children aged 2-10 years, undergoing LAP were randomized to receive PEEP of 5- or 10-cm H2O during pneumoperitoneum. Baseline hemodynamic and ventilatory parameters, PaO2, and PaCO2 were measured 2 min after tracheal intubation, 2 min and 1 h after pneumoperitoneum, and after deflation of pneumoperitoneum. Oxygenation index, dynamic compliance, and alveolar-arterial oxygen gradient (D (A-a) O2) were calculated at the above-mentioned time points. Data were analyzed using Student's t-test and repeated measures ANOVA with Bonferroni correction. The oxygenation index and D(A-a)O2 decreased in PEEP 5 Group and increased in PEEP 10 Group after pneumoperitoneum, the difference between the two groups being statistically significant (P = 0.001). The dynamic compliance decreased in PEEP 5 Group and increased or remained the same in PEEP 10 Group after pneumoperitoneum, the difference between the two groups being significant (P = 0.001). There were no significant changes in the hemodynamic parameters in the two groups. Use of 10-cm H2O PEEP during pneumoperitoneum in children improves ventilation and oxygenation, without significant hemodynamic changes.

RESPIRATORY PARAMETERS OF COVID-19 PATIENTS AFTER THE PRONE POSITION

&lt;p&gt;Hypoxemia is a condition when there is a lack of oxygen levels in the blood, especially from the arteries. In the early stages of COVID-19, several mechanisms such as intrapulmonary shunting, loss of pulmonary perfusion regulation, intravascular micro thrombus, and impaired diffusion capacity can contribute to the development of arterial hypoxemia, although there is no increase in respiratory work. The prone position is one of the most widely used therapies for patients with hypoxemia because the dorsal area has a large number of alveolar units that are not compressed by the weight of the abdominal cavity and mediastinum, thus creating a more efficient area for gas exchange. This study aimed to determine the effect of the prone position on changes in respiratory parameters of COVID-19 patients. This study used the descriptive correlation method on 27 respondents with purposive sampling. Each respondent was given a prone position for three hours and being observed before, during the three-hour, and after one hour of the prone position administration”. The results of the descriptive analysis of this study showed that the majority of respondents were middle adulthood (63%) with 70% of the respondents being male, 59% having a history of hypertension, and 85% experiencing coagulation disorders. The change in the mean respiratory rate during one hour of supination after three hours of prone position in males was greater than that in females although the mean decrease in oxygen saturation was the same. This shows that the prone position for three hours accompanied by oxygen therapy made an improvement in respiratory status in COVID-19 patients, although it needs further investigation with more respondents and different research methods.&lt;/p&gt;

Continuous monitoring of advanced hemodynamic parameters shows early cardiovascular changes in a cohort of 492 COVID-19 hospitalized patients

Abstract Background COVID-19 exerts deleterious cardiopulmonary effects, leading to worse prognosis in the most effected. Purpose The aim of this retrospective multi-center observational cohort study was to analyze the trajectories of key advanced hemodynamic parameters amongst hospitalized COVID-19 patients according to different risk populations using a chest-patch wearable providing continuous remote patient monitoring. Methods The study was conducted in five COVID-19 isolation units. Patients admitted to the units were connected to a photoplethysmography based noninvasive remote advanced hemodynamic monitor after completing a basic risk factor survey. Physiological parameters were measured every 15 minutes during the hospitalization, including cardiac output (CO), cardiac index (CI), systemic vascular resistance (SVR), heart rate, blood pressure (BP), respiratory rate, blood oxygen saturation (SpO2), and body temperature. Results 492 COVID-19 patients (179 females, average age 58.7 years) were included in the final analysis, with more than 3 million measurements collected during an average of 75.3 hours. Overall, within the first five days of hospitalizations we found a significant increase in SVR, and a significant decrease in SpO2, DBP, CO and CI (p&amp;lt;0.01 for all). The changes were more prominent in high risk populations- males, older age and obesity and had a temporal correspondence to changes in respiratory parameters. Conclusions This is the first comprehensive continuous advanced hemodynamic profiling of COVID-19 patients. Worse hemodynamic status was prominent in high risk populations. Funding Acknowledgement Type of funding sources: None.

Intravenous vasopressin leads to greater haemodynamic and respiratory responses in spontaneously hypertensive SHR rats than in normotensive controls

Introduction Increased activity of vasopressinergic system has been implicated in pathophysiology of essential hypertension. Intravenous or central administrations of vasopressin (AVP) were shown to affect not only hemodynamics, but also ventilatory function in rats. Receptors for AVP have been found in the brainstem structures involved in the control of breathing and in the carotid bodies. We hypothesized that given the involvement of AVP in essential hypertension and control of ventilation, AVP may differently affect hemodynamics and ventilation in spontaneously hypertensive (SHR) and in normotensive Wistar-Kyoto (WKY) rats. Purpose In the study we investigated the effects of intravenously administered AVP on hemodynamic and respiratory parameters under hypertensive and normotensive conditions. Methods The study was performed in urethane-anesthetizes adult male normotensive WKY (n=7) and hypertensive SHR rats (n=7). We implanted catheters into the femoral artery and femoral vein for recording mean arterial blood pressure (MABP) and for intravenous infusions, respectively. Additionally, we recorded minute ventilation (MV), respiratory rate (RR) and end-tidal CO2 (ET-CO2) via tracheal tube. We also placed subcutaneous ECG electrodes for heart rate (HR) monitoring. After obtaining baseline parameters, the arterial chemoreflex was triggered pharmacologically with intravenous (i.v.) administration of potassium cyanide (KCN) (30 microg/100 microL). After stabilization of hemodynamic and respiratory parameters, rats received i.v. administration of AVP (10ng/100μL) and recordings continued. Results SHR rats had significantly higher resting MABP, HR and MV than WKY controls. Both increases in MABP and MV and decrease in ET-CO2 were significantly greater in SHR than in WKY rats in response to pharmacologically triggered peripheral chemoreflex. One minute after administration of KCN, MV remained elevated above baseline and ET-CO2 was below baseline in SHR rats, whereas all respiratory parameters were normal in WKY rats. In SHR rats administration of AVP resulted in significantly greater increase in MABP than in WKY controls and was accompanied by reduction in MV and RR but no changes in HR. In WKY rats AVP resulted in smaller MABP increase accompanied by insignificant changes in respiratory parameters or HR. Conclusions Our findings confirm increased sensitivity of arterial chemoreflex in urethane-anesthetized SHR rats and suggest that AVP-dependent pressor and respiratory responses are enhanced in spontaneously hypertensive rats.

Development of chlorine-induced lung injury in the anesthetized, spontaneously breathing pig

Chlorine is a toxic industrial chemical produced in vast quantities globally, being used in a range of applications such as water purification, sanitation and industrial processes. Its use and transport cannot be restricted; exposure may occur following accidental or deliberate releases. The OPCW recently verified the use of chlorine gas against civilians in both Syria and Iraq. Chlorine inhalation produces damage to the lungs, which may result in the development of an acute lung injury, respiratory failure and death. Treatment remains an intractable problem. Our objective was to develop a clinically relevant pre-clinical model of a moderate to severe lung injury in the pig. This would enable future assessment of therapeutic drugs or interventions to be implemented in the pre-hospital phase after exposure. Due to the irritant nature of chlorine, a number of strategies for exposing terminally anesthetized pigs needed to be investigated. A number of challenges (inconsistent acute changes in respiratory parameters; early deaths), resulted in a moderate to severe lung injury not being achieved. However, most pigs developed a mild lung injury by 12 h. Further investigation is required to optimize the model and enable the assessment of therapeutic candidates. In this paper we describe the exposure strategies used and discuss the challenges encountered in establishing a model of chlorine-induced lung injury. A key aim is to assist researchers navigating the challenges of producing a clinically relevant model of higher dose chlorine exposure where animal welfare is protected by use of terminal anesthesia.

Comparison of High-Flow Humidified Oxygen With Conventional Continuous Positive Airway Pressure in Nonventilated Lungs During Thoracic Surgery: A Randomized Cross-Over Study

This study assessed the efficacy of high-flow humidified oxygen (HFHO) as an alternative to continuous positive airway pressure (CPAP) for improving oxygenation while preserving nonventilated lung collapse during one-lung ventilation. A prospective randomized cross-over trial. A tertiary medical center. The study comprised 28 patients undergoing elective thoracotomy with one-lung ventilation using a double-lumen endobronchial tube placement. The patients received prophylactic CPAP or HFHO to the nonventilated lung for 20 minutes and were then crossedover to the other oxygenation modality for 20 minutes, with a 20-minute recovery interval between the two modalities. Changes in respiratory parameters and lung deflation quality were recorded. Both CPAP and HFHO increased the partial pressure of arterial oxygen in either sequence in both groups, ranging from 31.8-to-66.0 mmHg. However, the increments from these two interventions were not statistically significant (95% confidence interval -12.84 to 21.87; p = 0.597). There were no differences in other parameters. Half the patients receiving CPAP experienced worsening of the surgical condition, whereas the HFHO patients experienced no change or reported a better lung deflation (p < 0.001). HFHO could be an alternative method to CPAP for improving arterial oxygenation while preserving lung deflation during one-lung ventilation. However, additional studies are warranted in regard to its cost-effectiveness and establishment as a routine treatment.

Assessment of Respiratory Function in Infants and Young Children Wearing Face Masks During the COVID-19 Pandemic

Face masks have been associated with effective prevention of diffusion of viruses via droplets. However, the use of face masks among children, especially those aged younger than 3 years, is debated, and the US Centers for Disease Control and American Academy of Physicians recommend the use of face mask only among individuals aged 3 years or older. To examine whether the use of surgical facial masks among children is associated with episodes of oxygen desaturation or respiratory distress. This cohort study was conducted from May through June 2020 in a secondary-level hospital pediatric unit in Italy. Included participants were 47 healthy children divided by age (ie, group A, aged ≤24 months, and group B, aged >24 months to ≤144 months). Data were analyzed from May through June 2020. All participants were monitored every 15 minutes for changes in respiratory parameters for the first 30 minutes while not wearing a surgical face mask and for the next 30 minutes while wearing a face mask. Children aged 24 months and older then participated in a walking test for 12 minutes. Changes in respiratory parameters during the use of surgical masks were evaluated. Among 47 children, 22 children (46.8%) were aged 24 months or younger (ie, group A), with 11 boys (50.0%) and median (interquartile range [IQR]) age 12.5 (10.0-17.5) months, and 25 children (53.2%) were aged older than 24 months to 144 months or younger, with 13 boys (52.0%) and median (IQR) age 100.0 (72.0-120.0) months. During the first 60 minutes of evaluation in the 2 groups, there was no significant change in group A in median (IQR) partial pressure of end-tidal carbon dioxide (Petco2; 33.0 [32.0-34.0] mm Hg; P for Kruskal Wallis = .59), oxygen saturation (Sao2; 98.0% [97.0%-99.0%]; P for Kruskal Wallis = .61), pulse rate (PR; 130.0 [115.0-140.0] pulsations/min; P for Kruskal Wallis = .99), or respiratory rate (RR; 30.0 [28.0-33.0] breaths/min; P for Kruskal Wallis = .69) or for group B in median (IQR) Petco2 (36.0 [34.0-38.0] mm Hg; P for Kruskal Wallis = .97), Sao2 (98.0% [97.0%-98.0%]; P for Kruskal Wallis = .52), PR (96.0 [84.0-104.5] pulsations/min; P for Kruskal Wallis test = .48), or RR (22.0 [20.0-25.0] breaths/min; P for Kruskal Wallis = .55). After the group B walking test, compared with before the walking test, there was a significant increase in median (IQR) PR (96.0 [84.0-104.5] pulsations/min vs 105.0 [100.0-115.0] pulsations/min; P < .02) and RR (22.0 [20.0-25.0] breaths/min vs 26.0 [24.0-29.0] breaths/min; P < .05). This cohort study among infants and young children in Italy found that the use of facial masks was not associated with significant changes in Sao2 or Petco2, including among children aged 24 months and younger.

Airway Pressure and Respiratory Mechanics Variability with Different Body Positions in Mechanically Ventilated Critical Care Patients: A Prospective Comparative Clinical Study

Aim: This prospective comparative study aimed to investigate the effect of various body positions on changes of respiratory parameters mostly; the TV, oxygen saturation, airway pressure, and endotracheal tube cuff pressure in mechanically ventilated critical care patients. Background: Many patients who are admitted to the critical care unit require intubation and invasive mechanical ventilation for many reasons such as major trauma, medical causes, or post-operative major surgeries. Changing a patient’s position in the critical care unit is very important for the following benefits; to break through the routine monotonic delivery of mechanical ventilation, to favor the clearance of respiratory secretions, the prevention of pressure sores and ventilator acquired pneumonia, and finally the improvement in lung volume and oxygenation. Methods: A prospective, comparative study was carried out on 210 patients of both gender, aged between 21-70 years old admitted to ICU due to many reasons. After stabilization of patient condition and connection of monitors’ cables, supine position or semi setting position was chosen and this was documented in the patient’s chart. All patients were sedated to prevent them from breathing against the machine which causes the ETT cuff pressure and mean airway pressure to rise. Fentanyl sedation drug (Loading dose: 1–2 mic/kg/hour infused gradually. Maintenance dose: 1-4 mic/kg/hour) using continuous intravenous infusion typically in combination with Midazolam sedation (0.05-0.2 mg/kg/hour). The following parameters were recorded; tidal volume, mean airway pressure, PO2 /FIO2 , and ETT cuff pressure. Results: Our results show that about (58.1%) were male and (41.9%) were female. Concerning age, their mean was between (40.6 ± 8.9) years. Regarding diagnosis (50.5%) of patients were admitted with major trauma, (31.9%) due to medical causes, and (17.6%) admitted due to major chest and abdominal surgeries. The patient’s mean heart rate was (93.6 ± 7.5) b/m and the Mean Arterial Pressure was (67.7 ± 0.6)°C. Tables the Description, SOP2, Mean airway, and ETT cuff pressure of each body position in the study with the highest SPO2 98% and cuff pressure 19.2+41 in the prone position. The position checklist is illustrated in Table and Figure. The highest TV (520 ml) and PO2 /FIO2 ratio (410) were in prone poison and the lowest was in Lower Fowler position (460 ml and 320) respectively. Regarding outcome and ICU stay which were the best in both semi setting and prone position. Conclusion: Supine position (lying flat) or lateral position do not seem beneficial for critically ill patients in terms of respiratory mechanics. The semi-sitting position (with thorax angulation=30° from the horizontal plane) is associated with improvement of PO2/FIO2 , oxygenation, and tidal volume, and the effects of prone position on respiratory mechanics are very beneficial and this reflected on patient outcome and short ICU length of stay.

Awake prone positioning for COVID-19 hypoxemic respiratory failure: A rapid review.

Abstract Background Infection with SARS-CoV-2 can result in Coronavirus Disease–19 (COVID-19) [1, 2]. While the majority of patients are asymptomatic or have mild disease [3], approximately 14% develop more severe disease including hypoxemic respiratory failure and/or Acute Respiratory Distress Syndrome (ARDS) [3]. Prone positioning is a life-saving intervention for mechanically ventilated patients with moderate-severe ARDS [4]. Based on this, the World Health Organization (WHO) guidelines recommend these patients be considered for a trial of prone positioning [5]. Recently the use of prone positioning in awake non-intubated COVID-19 patients has been recommended by several notable organizations with the goal of preventing intubation and potentially improving patient-oriented outcomes [6, 7]. In contrast to prone positioning for intubated mechanically ventilated patients with ARDS, there have been no randomized control trials examining the role of awake prone positioning for non-intubated patients with hypoxemic respiratory failure. To further explore this question we used rapid review methodology (Tricco et al., 2015 [8]) to quickly identify and synthesize studies examining the effect of awake prone positioning on patients with hypoxemic respiratory failure (including those with ARDS and/or COVID-19). Methods We have elected to use “rapid review” methodology rather than “systematic review” methodology primarily due to the speed and efficiency through which we are able to conduct this review, as previously described [8]. In the absence of an EQUATOR guidance document, we used PRISMA guidelines where applicable [9]. Studies were included if they met the following criteria 1) population – non-intubated patients with hypoxemic respiratory failure, 2) intervention – prone positioning, 3) comparator – usual management, 4) outcomes – intubation, survival, change in respiratory parameters, adverse events, 5) setting – hospitalized patients 6) study design – observational or randomized control trial. Studies were not limited to ARDS or COVID-19 patients. The search strategy was developed by a critical care physician (KP), a critical care epidemiologist (KF) and a medical librarian (NL) (See search details in Online Supplement). Briefly, the search strategy involved combinations of keywords and subject headings relating to the concepts of, 1) SARS-Cov-2 or COVID-19 or coronavirus, 2) awake prone positioning, and 3) hypoxemic respiratory failure, including but not limited to ARDS and other potentially relevant conditions. The search was conducted on May 19, 2020 and was updated on August 7, 2020 with no restrictions on publication language or date. Databases and grey literature sources searched included: MEDLINE (Ovid), PubMed, Trip PRO, Cochrane Library, LitCOVID, WHO COVID-19 Research Database, Centre for Evidence-Based Medicine (CEBM), National Institute for Health and Care Excellence (NICE), medRxiv, BMJ Best Practice, Cambridge Coronavirus Free Access Collection, and Google Scholar. Titles and abstracts were reviewed independently and in duplicate (KP and JW) for selection for full text review. Disagreements were resolved through discussion or with a third reviewer (KS). Full text review and data abstraction was conducted independently and in duplicate (KP, KS, JW). Data abstracted included study characteristics, participant demographics, and outcomes.

Internight Variability of Apnea-Hypopnea Index in Obstructive Sleep Apnea Using Ambulatory Polysomnography.

Rationale: Patients with obstructive sleep apnea (OSA) experience respiratory events with greater frequency and severity while in the supine sleeping position. Postural preference (associated with the sleep monitoring device) and “first night effect” could explain a night-to-night variability in OSA severity.Objectives: We evaluated the variability of internight polysomnography (PSG) in a large group of OSA patients and explored factors explaining this variability.Methods: 188 patients referred for probable OSA (aged 54.9 ± 11.8 y) underwent two consecutive nights of at-home PSG. The effect of age, gender, obesity, neck circumference, sleep position and sleep parameters were considered to explain changes in respiratory parameters.Main Results: The mean apnea-hypopnea index (AHI) and oxygen desaturation index (ODI) were respectively, 36.3 ± 27.5 and 22.0 ± 22.7 in the first night, with a tendency to decrease during the second night. While in mild cases (5 ≤ AHI < 15) there was a significant increase in AHI related to an increase in dorsal position time during the second night, there were no changes in moderate cases (15 ≤ AHI < 30); and in severe cases (AHI ≥ 30) there was a significant decrease in both AHI and ODI during the second night independent of sleep position.Conclusion: The internight variability in AHI and ODI was related to changes in sleep structure with a contribution of indices of sleep fragmentation and dorsal position. Since the changes were greater in mild OSA cases, a second night could be routinely proposed in cases with relevant clinical uncertainty.

Effects of Light and Nutrition Manipulations on Thermal Respiratory Acclimation and Nocturnal Dynamics of Leaf Dark Respiration

The ability of a plant to acclimate metabolically to thermal changes is necessary to maintain a positive carbon balance. It is likely that a plant’s acclimatory potential is a function of leaf nitrogen and/or leaf carbohydrate status. Two important issues assessed concerning leaf dark respiration (RD) were the effects of growth temperature, light, and fertilization on thermal respiratory acclimation and changes in respiratory parameters (indicative of acclimation) throughout the dark period. Soybean (Glycine max (L.) Merr.) plants were grown in greenhouses under a full factorial treatment arrangement of temperature, light, and nutrition. RD was measured at three temperatures to estimate respiratory parameters (cool respiration R13, warm respiration R25, and the temperature response of respiration EO) three times throughout the night (6 pm, 11 pm, and 4 am). Respiratory parameters did not differ throughout the night. Thermal acclimation was observed in warm grown plants under optimal growing conditions (i.e., high light and high fertilization); however, acclimation did not occur when limitations were imposed (i.e., shade or no fertilization). These findings suggest thermal acclimation will occur so long as plants do not undergo limitations. This may have major implications for natural ecosystems and may play a role in assessing an ecosystems resiliency to climate change.

The utility of HepaRG cells for bioenergetic investigation and detection of drug-induced mitochondrial toxicity

The importance of mitochondrial toxicity in drug-induced liver injury is well established. The bioenergetic phenotype of the HepaRG cell line was defined in order to assess their suitability as a model of mitochondrial hepatotoxicity. Bioenergetic phenotyping categorised the HepaRG cells as less metabolically active when measured beside the more energetic HepG2 cells. However, inhibition of mitochondrial ATP synthase induced an increase in glycolytic activity of both HepaRG and HepG2 cells suggesting an active Crabtree Effect in both cell lines. The suitability of HepaRG cells for the acute metabolic modification assay as a screen for mitotoxicity was confirmed using a panel of compounds, including both positive and negative mitotoxic compounds. Seahorse respirometry studies demonstrated that a statistically significant decrease in spare respiratory capacity is the first indication of mitochondrial dysfunction. Furthermore, based upon comparing changes in respiratory parameters to those of the positive controls, rotenone and carbonyl cyanide m-chlorophenyl hydrazone, compounds were categorised into two mechanistic groups; inhibitors or uncouplers of the electron transport chain. Overall, the findings from this study have demonstrated that HepaRG cells, despite having different resting bioenergetic phenotype to HepG2 cells are a suitable model to detect drug-induced mitochondrial toxicity with similar detection rates to HepG2 cells.

Assessing Sex‐Specific Effects of Ozone Exposure on Pulmonary Function and Lung Mechanics

BackgroundExposure to ground‐level ozone, an oxidative pollutant, causes lung inflammation, which can lead to pulmonary injury and impair lung innate immunity. There is emerging evidence that pulmonary diseases such as asthma affect women disproportionally with a greater degree of severity than men. In addition, most hospitalizations for asthma in women occur during the luteal phase or around the peri‐menstrual stage. However, the combined effect of ozone and sex hormones in respiratory mechanics is unclear. Here, we hypothesized that circulating estrogen levels can regulate pulmonary function and lung mechanics following ozone exposure.MethodsWe performed gonadectomy and hormone replacement (17β‐estradiol, 2 weeks) in a group of adult male and female C57BL/6 mice. In control females, the stages of the estrous cycle were monitored by daily by vaginal smear, and confirmed by serum sex hormone levels. We exposed animals to 1 ppm of ozone or filtered air (FA) for 3 hours, and we compared lung function 24h after exposure with a methacholine challenge (MCh; 0 – 50 mg/ml) using the FlexiVent system.ResultsWe observed significant changes in respiratory parameters (Ers, H, Rrs, RN, G) in males and females, and in females exposed to ozone at different stages of the estrous cycle, at the two highest MCh concentrations. The pressure‐volume curves obtained demonstrated similar MCh concentration‐dependent changes. Gonadectomized males exposed to ozone had higher Rrs and Ers than females and males exposed to FA, and treatment with estradiol ameliorated these effects. Surprisingly, female mice in the metestrus and diestrus stages exposed to FA had higher Rrs and Ers values than when compared to the proestrus and estrus stages. Contrarily, exposure to ozone caused a decrease in parameters (Ers, Rrs) during metestrus and diestrus stages, but a slight increase of these in the proestrus and estrus stages.ConclusionsOur results indicate that pulmonary function following ozone exposure can be affected by circulating hormone levels. Future studies examining diseases associated with environmental pollutants should consider the women's menstrual cycle.Support or Funding InformationThe authors thank the Pennsylvania State University College of Medicine Genome Sciences Core Facility for Bioanalyzer analysis. The authors also thank Todd Umstead and Susan Di Angelo for assistance with training and experiments, and Dr. Joanna Floros for the ozone equipment. NIH Grant K01HL133520.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Effects of caffeine administration on sedation and respiratory parameters in patients recovering from anesthesia.

Caffeine has been shown to enhance the speed of recovery from general anesthesia in murine models, though data in human patients is lacking. This is a retrospective review of intravenous caffeine administration (median dose 150 [125, 250] mg) to 151 heavily sedated patients in the post-anesthesia recovery area, to determine the association between caffeine administration and changes in sedation score, respiratory rate, and oxyhemoglobin saturation. Richmond Agitation-Sedation Scale (RASS) score, respiratory rate, and oxyhemoglobin saturation values were obtained during the 90-minute period prior to and following caffeine administration. Generalized estimating equations (GEE) with explanatory variables of time, caffeine, and the time-by-caffeine interaction were created to assess changes in the variables of interest after caffeine administration. Following the administration of caffeine, the RASS scores increased (estimate = 0.57, SE = 0.14, p < 0.001) but a trend over time or in the interaction effect was not observed, suggesting that the changes in RASS were not solely due to the recovery from anesthesia over time. No association was found between caffeine administration and changes in respiratory parameters. No adverse cardiac events were observed. Our data suggests that intravenous caffeine may enhance the speed of recovery following general anesthesia, though future prospective trials are necessary to define the optimal dose and timing of administration.