End-tidal Carbon Dioxide Partial Pressure Research Articles

A remote-controlled automatic chest compression device capable of moving compression position during CPR: A pilot study in a mannequin and a swine model of cardiac arrest.

Recently, we developed a chest compression device that can move the chest compression position without interruption during CPR and be remotely controlled to minimize rescuer exposure to infectious diseases. The purpose of this study was to compare its performance with conventional mechanical CPR device in a mannequin and a swine model of cardiac arrest. A prototype of a remote-controlled automatic chest compression device (ROSCER) that can change the chest compression position without interruption during CPR was developed, and its performance was compared with LUCAS 3 in a mannequin and a swine model of cardiac arrest. In a swine model of cardiac arrest, 16 male pigs were randomly assigned into the two groups, ROSCER CPR (n = 8) and LUCAS 3 CPR (n = 8), respectively. During 5 minutes of CPR, hemodynamic parameters including aortic pressure, right atrial pressure, coronary perfusion pressure, common carotid blood flow, and end-tidal carbon dioxide partial pressure were measured. In the compression performance test using a mannequin, compression depth, compression time, decompression time, and plateau time were almost equal between ROSCER and LUCAS 3. In a swine model of cardiac arrest, coronary perfusion pressure showed no difference between the two groups (p = 0.409). Systolic aortic pressure and carotid blood flow were higher in the LUCAS 3 group than in the ROSCER group during 5 minutes of CPR (p < 0.001, p = 0.008, respectively). End-tidal CO2 level of the ROSCER group was initially lower than that of the LUCAS 3 group, but was higher over time (p = 0.022). A Kaplan-Meier survival analysis for ROSC also showed no difference between the two groups (p = 0.46). The prototype of a remote-controlled automated chest compression device can move the chest compression position without interruption during CPR. In a mannequin and a swine model of cardiac arrest, the device showed no inferior performance to a conventional mechanical CPR device.

Effect of Blood Flow Restriction during the Rest Periods of Squats on Accuracy of Estimated Repetitions to Failure.

This study investigated the impact of resistance training with blood flow restriction during rest (BFRrest) on the accuracy of estimated repetitions to failure (ERF). It also explored associations between error in ERF and mean concentric velocity (MCV) along with physiological responses. In a randomised cross-over study, 18 male trainers (23.4 ± 2.7 years) performed three sets of squats at 70% of their one-repetition maximum until failure. One session integrated BFRrest, while another employed traditional passive inter-set rest (TRAD) during the 3 min inter-set rest intervals. Cardiorespiratory and metabolic measures were taken in the inter-set recovery periods. The results revealed no significant differences between BFRrest and TRAD in terms of ERF and error in ERF. A notable set effect for ERF was observed, with a greater ERF during set 1 compared to sets 2 and 3 (p < 0.001). Additionally, a lower error in ERF was observed during sets 2 and 3 compared to set 1 (p < 0.001). Error in ERF were strongly associated with the respiratory exchange ratio, and moderately associated with end-tidal carbon dioxide partial pressure, carbon dioxide output, and MCV variables. Notably, the precision of ERF seems to be predominantly influenced by indicators of physiological stress rather than the incorporation of BFRrest.

Comparison of the Buffalo Concussion Treadmill Test With a Physiologically Informed Cycle Test: Calgary Concussion Cycle Test.

Sport-related concussions are a complex injury requiring multifaceted assessment, including physical exertion. Currently, concussion testing relies primarily on a treadmill-based protocol for assessing exertion-related symptoms in persons after concussion. This study compared a modified cycle protocol (Calgary Concussion Cycle Test [CCCT]) with the clinically adopted standard, the Buffalo Concussion Treadmill Test (BCTT), across multiple physiological parameters. Treadmill and cycle matched workload protocols would produce similar results for cerebral blood velocity, mean arterial pressure (MAP), and end-tidal carbon dioxide partial pressure (PETCO2), but heart rate (HR) and oxygen consumption (VO2) would be higher on the treadmill than the cycle modality. Crossover study design. Level 3. A total of 17 healthy adults (8 men, 9 women; age, 26 ± 3 years; body mass index, 23.8 ± 2.7 kg/m2) completed the BCTT and CCCT protocols, 7 days apart in a randomized order. During both exertional protocols, the physiological parameters measured were middle cerebral artery mean blood velocity (MCAv), MAP, PETCO2, VO2, and HR. Analysis of variance with effect size computations, coefficient of variation, and Bland-Altman plots with 95% limits of agreement were used to compare exercise tests. The BCTT and CCCT produced comparable results for both male and female participants with no significant differences for average MCAv, MAP, and PETCO2 (all P > 0.05; all generalized eta squared [η2G] < 0.02 [negligible]; P value range, 0.29-0.99) between stages. When accounting for exercise stage and modality, VO2 (P < 0.01) and HR (P < 0.01) were higher on the treadmill compared with the cycle. Aside from the final few stages, all physiology measures displayed good-to-excellent agreeability/variability. The CCCT was physiologically similar to the BCTT in terms of MCAv, PETCO2, and MAP; however, HR and VO2 differed between modalities. Providing a cycle-based modality to exertional testing after injury mayincrease accessibility to determine symptom thresholds in the future.

Comparison of ventilatory parameters with nasal versus oral breathing during submaximal exercise in patients with cardiac disease and healthy people

Abstract Introduction Inefficient ventilation, namely a high ventilation/carbon dioxide production ratio (VE/VCO2) is a well established predictor for disease progression and mortality in patients with heart failure (HF). Two previous studies in healthy people have found improved ventilatory efficiency with nasal compared to oral breathing during submaximal exercise. No study has compared nasal with oral breathing in patients with HF or coronary heart disease. Method Four study groups were recruited: Patients with HF, patients with acute or chronic coronary syndrome (ACS/CCS), old healthy controls (age&amp;gt;45 years) and young healthy controls (age&amp;gt;20 years and &amp;lt;35 years). Acute measurements of 5 min (after 3 min warm-up) with nasal and 5 min with oral breathing in randomized order were performed at 50% peak power. Ventilation parameters were averaged over the last minute of each condition and analysed by linear mixed models adjusted for body mass index. Results We present data of 8 patients with HF, 8 with ACS/CCS, 10 old and 15 young healthy controls. Minute ventilation, breathing frequency and end-tidal oxygen partial pressure (PETO2) were significantly lower and tidal volume and end-tidal carbon dioxide partial pressure (PETCO2) significantly higher during nasal compared to oral breathing in all groups (Figure 1). Differences between breathing modes were between 5-20% and similar in all groups except for breathing frequency that declined more from oral to nasal breathing, namely by 27%, in patients with HF compared to the other groups. The largest discrepancies between patients and healthy controls were found for VE/VCO2 ratio, PETCO2 and PETO2. Conclusion Nasal breathing during submaximal exercise significantly improved the abnormal breathing pattern of patients with HF and ACS/CCS. Nasal breathing during exercise may be promising in patients with inefficient ventilation as it increases PETCO2 and is likely to increase arterial partial CO2 pressure, a known vasodilator, herewith facilitating perfusion of the working musculature.Figure 1

Effects of N95 Masks on Cerebral Oxygen Saturation and End-Tidal Carbon Dioxide Partial Pressure in Healthcare Workers

Background: Healthcare workers must wear masks throughout their shifts, especially those in operating rooms for long periods. Objectives: This study evaluated the effects of wearing N95 masks on blood and cerebral oxygen saturation levels for three hours. Methods: The present case-control study enrolled 20 operating room workers wearing N95 masks. Their blood oxygen saturation (SaO2), end-tidal carbon dioxide partial pressure (PETCO2), and right- and left-sided cerebral regional oxygen saturation (rSO2) were measured in the beginning (0 h) and after wearing N95 masks for one and three hours. Results: Wearing a mask affected PETCO2, rSO2, and pulse rate and caused fatigue and lightheadedness in some cases. The participants' mean PETCO2 increased significantly, from 32 mmHg before putting on a mask to 38 mmHg after wearing it for three hours (P &lt; 0.05). No significant change was observed in the participants' mean rSO2, though changes in their rSO2 levels were recorded (P &gt; 0.05). Conclusions: We showed evidence of changes in different physiology parameters due to using masks for 1 to 3 h. Notably, wearing an N95 mask increased end-tidal carbon dioxide partial pressure and decreased cerebral oxygen saturation in individual cases, not all cases.

Effects of remimazolam combined with sufentanil on hemodynamics during anesthetic induction in elderly patients with mild hypertension undergoing orthopedic surgery of the lower limbs: a randomized controlled trial

BackgroundThis randomized controlled trial was performed to observe the effect of remimazolam with sufentanil on hemodynamics during anesthetic induction in elderly patients with mild hypertension undergoing orthopedic surgery of the lower limbs.MethodsSixty elderly patients were randomly assigned to undergo general anesthesia with intravenous injection of either remimazolam besylate (25 mg/vial, batch number 10T11011; Yichang Humanwell Pharmaceutical Co., Ltd., Yichang, China) at 0.2 mg/kg (Group R, n = 30) or propofol at 1.5 mg/kg (Group P, n = 30). Both injections were completed within 15 to 20 s. If the bispectral index value did not reach 40 to 60, then 0.05 mg/kg of remimazolam was added in Group P and 1 mg/kg of propofol was added in Group R. When the BIS value reached 40 to 60, sufentanil was administered at 0.3 to 0.5 µg/kg and cisatracurium was administered at 0.15 to 0.2 mg/kg in both groups. Three minutes later, tracheal intubation and controlled ventilation were performed to maintain the end-tidal carbon dioxide partial pressure at 4.5 to 5.0 kPa. The mean arterial pressure (MAP), heart rate (HR), cardiac output (CO), continuous cardiac index (CI), systemic vascular resistance (SVR), and pulse oxygen saturation were recorded before induction (T0), when the eyelash reflex disappeared (T1), immediately after endotracheal intubation (T2), 1 min after endotracheal intubation (T3), and 5 min after endotracheal intubation (T4). The disappearance time of the eyelash reflex, injection pain, hypotension, bradycardia, hiccupping, nausea and vomiting, and other adverse events were observed.ResultsThe MAP, HR, CO, and CI at T1, T2, T3, and T4 were significantly higher in Group R than P, while SVR was significantly lower in Group R than P (P < 0.05). In Group P, the MAP, HR, CO, and CI were significantly lower and the SVR was significantly higher at T1, T2, T3, and T4 than at T0 (P < 0.05). Adverse events occurred in 8 (20%) patients in Group R and 22 (73%) in Group P. The total incidence of adverse events was significantly lower in Group R than P (P < 0 0.001).ConclusionRemimazolam combined with sufentanil for general anesthesia induction has the advantages of small hemodynamic fluctuations, stable circulation, and few adverse reactions, making it suitable for elderly patients with mild hypertension.Trial registrationChinese Clinical Trial Registry (ChiCTR2300069224, 10/03/2023).

A quasi-experimental study of fresh oxygen flow on patients' oxygen reserve during mask-assisted ventilation under general anesthesia induction.

To compare the effect of different amounts of fresh oxygen flow on oxygen reserve in patients undergoing general anesthesia. Seventy-two patients were enrolled in this quasi-experimental study. Patients were randomly divided into experimental groups with a fresh oxygen flow of 1 L/min, 2 L/min, 4 L/min, and 8 L/min (denoted as G1, G2, G3, and G4, respectively) for 2 min of mask-assisted ventilation. Safe apnea time (SAT) was the primary endpoint; SAT was defined as the time from the cessation of ventilation to the time the patient's pulse oxygen saturation (SpO2) decreased to 90%. Ventilation indicators such as end-tidal oxygen concentration (EtO2), end-tidal carbon dioxide partial pressure (EtCO2), SpO2, and carbon dioxide (CO2) elimination amount, during mask-assisted ventilation, were the secondary endpoints. The SAT of G1, G2, G3, and G4 were 305.1 ± 97.0 s, 315 ± 112.5 s, 381.3 ± 118.6 s, and 359 ± 104.4 s, respectively (p > 0.05). The EtO2 after 2 min of mask-assisted ventilation in groups G1, G2, G3, and G4 were 69.7 ± 8.8%, 75.2 ± 5.0%, 82.5 ± 3.3%, and 86.8 ± 1.5%, respectively (p < 0.05). Also, there was a moderate positive correlation between the fresh oxygen flow and EtO2 (correlation coefficient r = 0.52, 95% CI 0.31-0.67, p < 0.0001). The CO2 elimination in the G1 and G2 groups was greater than that in the G4 group (p < 0.05). There was no significant difference in other indicators among the groups (all p > 0.05). The amount of fresh oxygen flow during mask-assisted ventilation was positively correlated with EtO2. Also, even though there was no significant difference, the patients' oxygen reserves increased with the increase in fresh oxygen flow.

Effects of targeted mild hypercapnia versus normocapnia on cerebral oxygen saturation in patients undergoing laparoscopic hepatectomy under low central venous pressure: a prospective, randomized controlled study

BackgroundLaparoscopic hepatectomy under low central venous pressure (LCVP) is associated with intraoperative organ hypoperfusion, including cerebral hypoperfusion. We hypothesized that a ventilation strategy designed to achieve targeted mild hypercapnia (TMH) (end-tidal carbon dioxide partial pressure [PetCO2] of 45 ± 5 mmHg) rather than targeted normocapnia (TN) (PetCO2 of 30 ± 5 mmHg) would increase regional cerebral oxygen saturation (rSO2) during laparoscopic hepatectomy under LCVP.MethodsEighty patients undergoing laparoscopic hepatectomy under LCVP were randomly divided into the TMH group (n = 40) and the TN group (n = 40). Mechanical ventilation was adjusted to maintain the PetCO2 within the relevant range. Cerebral oxygenation was monitored continuously using the FORE-SIGHT system before anesthetic induction until the patient left the operating room. Patient and surgical characteristics, rSO2, intraoperative hemodynamic parameters (CVP, mean artery blood pressure [MAP], and heart rate), PetCO2, intraoperative blood gas analysis results, and postoperative complications were recorded.ResultsNo significant differences were observed in CVP, MAP, and heart rate between the two groups during surgery. The rSO2 was significantly lower in the TN group on both the left and right sides during the intraoperative period (P < 0.05), while the TMH group had a stable rSO2. In the TN group, the mean rSO2 decreased most during liver parenchymal transection when compared with the baseline value (P < 0.05). The mean (standard deviation) percentage change in rSO2 from baseline to parenchymal transection was − 7.5% (4.8%) on the left and − 7.1% (4.6%) on the right. The two groups had a similar incidence of postoperative complications (P > 0.05).ConclusionOur findings demonstrate that rSO2 is better maintained during laparoscopic hepatectomy under LCVP when patients are ventilated to a PetCO2 of 45 ± 5 mmHg (TMH) than a PetCO2 of 30 ± 5 mmHg (TN).Trial registrationChiCTR2100051130(14/9/2021).

Oral Oxycodone-Induced Respiratory Depression During Normocapnia and Hypercapnia: A Pharmacokinetic-Pharmacodynamic Modeling Study.

The widely prescribed opioid oxycodone may cause lethal respiratory depression. We compared the effects of oxycodone on breathing and antinociception in healthy young volunteers. After pharmacokinetic/pharmacodynamic (PK/PD) modeling, we constructed utility functions to combine the wanted and unwanted end points into a single function. We hypothesized that the function would be predominantly negative over the tested oxycodone concentration range. Twenty-four male and female volunteers received 20 (n=12) or 40 (n=12) mg oral oxycodone immediate-release tablets. Hypercapnic ventilatory responses (visit 1) or responses to 3 nociceptive assays (pain pressure, electrical, and thermal tests; visit 2) were measured at regular intervals for 7 hours. the PK/PD analyses, that included carbon dioxide kinetics, stood at the basis of the utility function: probability of antinociception minus probability of respiratory depression. Oxycodone had rapid onset/offset times (30-40 minutes) with potency values (effect-site concentration causing 50% of effect) ranging from 0.05 to 0.13 ng/mL for respiratory variables obtained at hypercapnia and antinociceptive responses. Ventilation at an extrapolated end-tidal carbon dioxide partial pressure of 55 mmHg, was used for creation of 3 utility functions, one for each of the nociceptive tests. Contrary to expectation, the utility functions were close to zero or positive over the clinical oxycodone concentration range. The similar or better likelihood for antinociception relative to respiratory depression may be related to oxycodone's receptor activation profile or to is high likeability that possibly alters the modulation of nociceptive input. Oxycodone differs from other μ-opioids, such as fentanyl, that have a consistent negative utility.

Sedentary behaviour, but not moderate-to-vigorous physical activity, is associated with respiratory responses to acute psychological stress

BackgroundAcute psychological stress induces respiratory responses, and stress-induced respiratory changes can be used to non-invasively reflect metabolic regulation. Respiratory and cardiovascular responses to stress are both driven by sympathetic mechanisms. Higher volumes of sedentary behaviour and lower volumes of physical activity are associated with elevated sympathetic tone and larger cardiovascular responses to stress. The aim of this study was to test whether these associations translate to measures of respiratory stress reactivity. MethodsDaily hours of sedentary behaviour (thigh-mounted activPAL) and moderate-to-vigorous physical activity (MVPA; wrist-mounted ActiGraph) were assessed across seven days. Breath-by-breath respiratory (e.g., breathing frequency [BF], end-tidal carbon dioxide partial pressure [PetCO2], carbon dioxide output [V̇CO2] and respiratory exchange ratio [RER]) responses to an 8-min Paced Auditory Serial Addition Test were then measured using a Cortex MetaLyzer3B. ResultsHealthy participants (N = 61, mean age ± SD = 25.7 ± 8.9 years) recorded high volumes of sedentary behaviour (9.96 ± 1.48 h/day) and MVPA (1.70 ± 0.71 h/day). In adjusted models (with the inclusion of sedentary behaviour, MVPA, and other a priori selected covariates) hours of daily sedentary behaviour were associated with baseline to stress changes in BF (Β = 0.695, 95% CI = 0.281 — 1.109, p = .014), VT (Β = −0.042, 95% CI = −0.058 — −0.026, p = .014), PetCO2 (Β = −0.537, 95% CI = −0.829 — −0.245, p = .014), V̇CO2 (Β = −0.008, 95% CI = −0.014 — −0.003, p = .030), and RER (Β = −0.013, 95% CI = −0.021 — −0.005, p = .022). Daily hours of MVPA were not linked with respiratory responses to stress. DiscussionSedentary behaviour, but not MVPA, is associated with respiratory stress reactivity. Future work should untangle the underlying mechanisms of these findings and explore the consequences for cardiometabolic disease.

Noninvasive carbon dioxide monitoring in pediatric patients undergoing laparoscopic surgery: transcutaneous vs. end-tidal techniques

PurposeThe present study aimed to investigate the correlation between transcutaneous carbon dioxide partial pressure (PtcCO2) and arterial carbon dioxide pressure (PaCO2) and the accuracy of PtcCO2 in predicting PaCO2 during laparoscopic surgery in pediatric patients.MethodsChildren aged 2–8 years with American Society of Anesthesiologists (ASA) class I or II who underwent laparoscopic surgery under general anesthesia were selected. After anesthesia induction and tracheal intubation, PtcCO2 was monitored, and radial arterial catheterization was performed for continuous pressure measurement. PaCO2, PtcCO2, and end-tidal carbon dioxide partial pressure (PetCO2) were measured before pneumoperitoneum, and 30, 60, and 90 min after pneumoperitoneum, respectively. The correlation and agreement between PtcCO2 and PaCO2, PetCO2, and PaCO2 were evaluated.ResultsA total of 32 patients were eventually enrolled in this study, resulting in 128 datasets. The linear regression equations were: PtcCO2 = 7.89 + 0.82 × PaCO2 (r2 = 0.70, P < 0.01); PetCO2 = 9.87 + 0.64 × PaCO2 (r2 = 0.69, P < 0.01). The 95% limits of agreement (LOA) of PtcCO2 – PaCO2 average was 0.66 ± 4.92 mmHg, and the 95% LOA of PetCO2 – PaCO2 average was –4.4 ± 4.86 mmHg. A difference of ≤ 5 mmHg was noted between PtcCO2 and PaCO2 in 122/128 samples and between PetCO2 and PaCO2 in 81/128 samples (P < 0.01).ConclusionIn pediatric laparoscopic surgery, a close correlation was established between PtcCO2 and PaCO2. Compared to PetCO2, PtcCO2 can estimate PaCO2 accurately and could be used as an auxiliary monitoring indicator to optimize anesthesia management for laparoscopic surgery in children; however, it is not a substitute for PetCO2.Registration number of Chinese Clinical Trial RegistryChiCTR2100043636.

Case of intraoperative acute pulmonary embolism diagnosed by transesophageal echocardiography under general anesthesia and successfully managed with extracorporeal membrane oxygenation

Acute pulmonary thromboembolism (PTE), which carries a high mortality rate, is difficult to diagnose when it occurs intraoperatively. Therefore, patient prognosis depends on a prompt diagnosis by anesthesiologists. A 49-year-old woman underwent right lower extremity dissection due to a contusion of the right lower extremity caused by trauma. Eleven days after surgery, she underwent debridement for necrosis of the amputation wound. Intraoperatively, a drop in blood pressure and tachycardia were observed, and PTE was suspected based on a rapid deterioration in oxygen saturation and a drop in end-tidal carbon dioxide partial pressure. Transesophageal echocardiography (TEE) showed a thrombus filling the right pulmonary artery, and a diagnosis of PTE was made. The patient was treated using venoarterial extracorporeal membrane oxygenation, and thrombectomy was performed the next day to save her life. In this case, we were able to diagnose and treat the intraoperative acute PTE at an early stage. In addition, the appropriate choice of treatment saved the patient’s life without complications.

Ventilatory And Cardiovascular Acclimatization Remains Unchanged Following Active Versus Passive Ascent To 3600 m

PURPOSE: Sympathetic stimulation, induced by intense endurance exercise, may alter the process of ventilatory and cardiovascular acclimatization. The purpose of this study was to examine the magnitude and time course of ventilatory and cardiovascular acclimatization following active and passive ascent to 3600 m. METHODS: Forty-one healthy unacclimatized Soldiers (n = 41, mean ± SD; age = 26 ± 5 yr; body weight = 83.5 ± 11.6 kg; VO2max = 47.9 ± 5.5 ml · kg−1 · min−1) were tested at sea level (SL) in Ft. Leonard Wood, MO, flown to Taos Ski Valley, NM (2845 m) where they arrived around 1400 m, and then either hiked (n = 21; 5.0 km, 15.5% mean grade) or were driven (n = 20; 30-min drive) to a high altitude (HA) ski patrol facility located at 3600 m. Energy expenditure during ascent was measured with an ankle accelerometer. Portable real-time capnography was used to measure end-tidal carbon dioxide partial pressure (PETCO2) after 10 min of sitting at SL, after 19 h (HA2), 43 h (HA3), and 67 h (HA4) at HA. Mean arterial blood pressure (MAP), heart rate (HR), and pulse arterial oxygen saturation (SpO2) were measured at the same time (~0900) as PETCO2 RESULTS: The active group expended a greater (P < 0.05) amount of energy (745 ± 435 kcal) than the passive group (55 ± 10 kcal) during ascent. There were no differences between groups in terms of ventilatory and cardiovascular acclimatization so data were combined. Resting PETCO2 (mmHg) decreased (P < 0.05) from SL (37.5 ± 3.35) to HA2 (33.5 ± 3.71), remained stable from HA2 to HA3 (33.8 ± 3.73) and decreased further (P < 0.05) from HA3 to HA4 (30.8 ± 4.9). Resting MAP and HR, respectively, increased (P < 0.05) from SL (89.9 ± 6.9 mmHg; 65.7 ± 9.8 bpm) to HA2 (100.0 ± 7.2 mmHg; 78.7 ± 10.1 bpm), MAP decreased (P < 0.05) but HR remained unchanged from HA2 to HA3 (96.9 ± 7.1 mmHg; 78.5 ± 15.4 bpm), and both stayed consistent from HA3 to HA4 (98.1 ± 7.1 mmHg; 80.1 ± 12.9 bpm). Resting SpO2 (%) decreased (P < 0.05) from SL (97.6 ± 1.3) to HA2 (88.7 ± 3.1), increased (P < 0.05) from HA2 to HA3 (89.7 ± 2.9), and remained unchanged from HA3 to HA4 (89.1 ± 3.2). CONCLUSION: Ventilatory and cardiovascular acclimatization occurred at HA but sympathetic stimulation and increased metabolic rate due to the active ascent did not change the magnitude or time course of either of these processes. Authors’ views not official U.S. Army or DoD policy. Funding: USAMRDC

Postoperative mortality risk prediction that incorporates intraoperative vital signs: development and internal validation in a historical cohort.

Accurate risk reassessment after surgery is crucial for postoperative planning for monitoring and disposition. Existing postoperative mortality risk prediction models using preoperative features do not incorporate intraoperative hemodynamic derangements that may alter risk stratification. Intraoperative vital signs may provide an objective and readily available prognostic resource. Our primary objective was to derive and internally validate a logistic regression (LR) model by adding intraoperative features to established preoperative predictors to predict 30-day postoperative mortality. Following Research Ethics Board approval, we analyzeda historical cohort that included patients aged ≥ 45 undergoing noncardiac surgery with an overnight stay at two tertiary hospitals (2013 to 2017). Features included intraoperative vital signs (blood pressure, heart rate, end-tidal carbon dioxide partial pressure, oxygen saturation, and temperature) by threshold and duration of exposure, as well as patient, surgical, and anesthetic factors. The cohort was divided temporally 75:25 into derivation and validation sets. We constructed a multivariable LR model with 30-day all-cause mortality as the outcome and evaluated performance metrics. There were 30,619 patients in the cohort (mean [standard deviation] age, 66 [11] yr; 50.2% female; 2.0% mortality). In the validation set, the primary LR model showed a c-statistic of 0.893 (99% confidence interval [CI], 0.853 to 0.927), a Nagelkerke R-squared of 0.269, a scaled Brier score of 0.082, and an area under precision-recall curve of 0.158 (baseline 0.017 for an uninformative model). The addition of intraoperative vital signs to preoperative factors minimally improved discrimination and calibration. We derived and internally validated a model that incorporated vital signs to improve risk stratification after surgery. Preoperative factors were strongly predictive of mortality risk, and intraoperative predictors only minimally improved discrimination. External and prospective validations are needed. www. gov (NCT04014010); registered on 10 July 2019.

Randomized clinical trial of capnometry-assisted respiratory training in veterans with posttraumatic stress disorder hyperarousal.

To investigate whether capnometry-assisted antihyperventilation respiratory training, successful in treating panic, and sleep hygiene instructions would reduce posttraumatic stress disorder (PTSD) hyperarousal symptoms in U.S. military veterans. We conducted a parallel, nonblinded clinical trial and randomized 80 veterans with PTSD hyperarousal into treatment or wait list. Primary treatment outcomes from baseline to 1st follow-up were analyzed using mixed modeling. Baseline physiological measures were compared between the PTSD hyperarousal group and a no-PTSD group (n = 68). Baseline respiration rate but not partial-pressure of end-tidal carbon dioxide (PCO₂) was higher in the PTSD hyperarousal group than in the no-PTSD group during 3 min of quiet sitting, indicating no difference in baseline hyperventilation. There was no significant effect of the intervention on PTSD hyperarousal symptoms or hyperventilation compared to wait list, but treatment did lower respiratory rate. This intervention did not reduce PTSD hyperarousal symptoms, perhaps due to differences between underlying mechanisms of PTSD hyperarousal and panic disorder or to differences between veteran and civilian populations. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Effects of high-flow nasal oxygen combined with early extubation on the incidence of respiratory adverse events during emergence from general anesthesia in children undergoing adenoid-tonsillectomy

Objective: To investigate the effects of high-flow nasal oxygen (HFNO) combined with early extubation on the incidence of respiratory adverse events (RAE) during emergence from general anesthesia in children undergoing adenoid-tonsillectomy. Methods: From December 2021 to January 2022, 40 pediatric patients [21 males, 19 females, with a median age of 4 (4, 5) years] undergoing tonsillectomy and/or adenoidectomy in Eye & ENT Hospital of Fudan University were randomly divided into two groups: HFNO-assisted early extubation group (Group H, n=20) and conventional extubation group (Group C, n=20) by using a random number table. After entering the post-anesthesia care unit (PACU), the patients in group H received humidified and heated oxygen (flow rate: 25 L/min) through a nasal cannula until their consciousness regained. After patient's spontaneous breathing resumed for 10 min, the oral endotracheal tube was removed. Patients in group C did not receive HFNO. The oral endotracheal tube was removed after the patient's spontaneous breathing resumed for at least 10 min with signs of tube intolerance, or 20 min without signs of tube intolerance. During the PACU stay, the incidence of RAE, the incidence of cough, the application rate of intensive care strategy, the time to extubation, the duration of PACU stay, and vital signs at spontaneous breathing resuming and extubation in each group were recorded. Results: In Group H, the total incidence of RAE [30% (6/20) vs 65% (13/20), P=0.027], the incidence of cough [10% (2/10) vs 45% (9/20), P=0.031] and the application rate of intensive care strategy [20% (4/20) vs 55% (11/20), P=0.048] during PACU stay was significantly lower, compared with those of Group C. Likewise, the time to extubation was significantly shorter [(33.4±4.5) min vs (42.7±5.3) min, P<0.001]. However, there was no statistically significant difference in the duration of PACU stay, the vital signs at the time of spontaneous breathing resuming and extubation between the two groups (P>0.05), except that the end-tidal carbon dioxide partial pressure (PETCO2) at the time of extubation in group H was significantly higher than group C [(52.9±9.4) mmHg vs (48.9±3.1) mmHg (1 mmHg=0.133 kPa), P<0.001]. Conclusion: HFNO combined with early extubation can significantly reduce the incidence of RAE in children undergoing adenoid-tonsillectomy during the emergence from general anesthesia.

End-Tidal to Arterial Pco2 Ratio as Guide to Weaning from Venovenous Extracorporeal Membrane Oxygenation.

Rationale: Weaning from venovenous extracorporeal membrane oxygenation (VV-ECMO) is based on oxygenation and not on carbon dioxide elimination. Objectives: To predict readiness to wean from VV-ECMO. Methods: In this multicenter study of mechanically ventilated adults with severe acute respiratory distress syndrome receiving VV-ECMO, we investigated a variable based on CO2 elimination. The study included a prospective interventional study of a physiological cohort (n = 26) and a retrospective clinical cohort (n = 638). Measurements and Main Results: Weaning failure in the clinical and physiological cohorts were 37% and 42%, respectively. The main cause of failure in the physiological cohort was high inspiratory effort or respiratory rate. All patients exhaled similar amounts of CO2, but in patients who failed the weaning trial, [Formula: see text]e was higher to maintain the PaCO2 unchanged. The effort to eliminate one unit-volume of CO2, was double in patients who failed (68.9 [42.4-123] vs. 39 [20.1-57] cm H2O/[L/min]; P = 0.007), owing to the higher physiological Vd (68 [58.73] % vs. 54 [41.64] %; P = 0.012). End-tidal partial carbon dioxide pressure (PetCO2)/PaCO2 ratio was a clinical variable strongly associated with weaning outcome at baseline, with area under the receiver operating characteristic curve of 0.87 (95% confidence interval [CI], 0.71-1). Similarly, the PetCO2/PaCO2 ratio was associated with weaning outcome in the clinical cohort both before the weaning trial (odds ratio, 4.14; 95% CI, 1.32-12.2; P = 0.015) and at a sweep gas flow of zero (odds ratio, 13.1; 95% CI, 4-44.4; P < 0.001). Conclusions: The primary reason for weaning failure from VV-ECMO is high effort to eliminate CO2. A higher PetCO2/PaCO2 ratio was associated with greater likelihood of weaning from VV-ECMO.

The impacts of surgical mask in young healthy subjects on cardiopulmonary function and muscle performance: a randomized crossover trial

ObjectiveTo explore the impacts of surgical mask in normal subjects on cardiopulmonary function and muscle performance under different motor load and gender differences.DesignRandomized crossover trial.SettingThe Fifth Affiliated Hospital of Guangzhou Medical University, June 16th to December 30th, 2020.ParticipantsThirty-one college students (age: male 21.27 ± 1.22 years; female 21.31 ± 0.79 years) were recruited and randomly allocated in two groups.InterventionsGroup 1 first received CPET in the mask-on condition followed by 48 h of washout, and then received CPET in the mask-off condition. Group 2 first received CPET in the mask-off condition followed by 48 h of washout, then received CPET in the mask-on condition. The sEMG data were simultaneously collected.Main outcome measuresThe primary outcome was maximum oxygen uptake (VO2 max) from CPET, which was performed on a cycle ergometer—this is the most important parameter associated with an individual’s physical conditioning. The secondary parameters included parameters reflecting exercise tolerance and heart function (oxygen uptake, anaerobic valve, maximum oxygen pulse, heart rate reserve), parameters reflecting ventilation function (respiration reserve, ventilation volume, tidal volume, breathing frequency), parameters reflecting gas exchange (end-tidal oxygen and carbon dioxide partial pressure, oxygen equivalent, carbon dioxide equivalent, and the relationship between dead space and tidal volume) and parameters reflecting skeletal muscle function [oxygen uptake, anaerobic valve, work efficiency, and EMG parameters including root mean square (RMS)].ResultsComparing the mask-on and mask-off condition, wearing surgical mask had some negative effects on VO2/kg (peak) and ventilation (peak) in both male and female health subjects [VO2/kg (peak): 28.65 ± 3.53 vs 33.22 ± 4.31 (P = 0.001) and 22.54 ± 3.87 vs 26.61 ± 4.03 (P < 0.001) ml/min/kg in male and female respectively; ventilation (peak): 71.59 ± 16.83 vs 82.02 ± 17.01 (P = 0.015) and 42.46 ± 10.09 vs 53.95 ± 10.33 (P < 0.001) liter in male and female respectively], although, based on self-rated scales, there was no difference in subjective feelings when comparing the mask-off and mask-on condition. Wearing surgical masks showed greater lower limb muscle activity just in male subjects [mean RMS of vastus medialis (load): 65.36 ± 15.15 vs 76.46 ± 19.04 μV, P = 0.031]. Moreover, wearing surgical masks produced a greater decrease in △tidal volume (VTpeak) during intensive exercises phase in male subjects than in female [male − 0.80 ± 0.15 vs female − 0.62 ± 0.11 l P = 0.001].ConclusionsWearing medical/surgical mask showed a negative impact on the ventilation function in young healthy subjects during CPET, especially in high-intensity phase. Moreover, some negative effects were found both in ventilation and lower limb muscle actives in male young subjects during mask-on condition. Future studies should focus on the subjects with cardiopulmonary diseases to explore the effect of wearing mask.Trial registrationChinese Clinical Trial Registry (ChiCTR2000033449).

Cardiopulmonary exercise testing to observe subclinical abnormalities in cardiopulmonary function in patients undergoing peritoneal dialysis.

Decreased cardiorespiratory fitness (CRF) related to cardiopulmonary function increases the risk of cardiovascular disease in patients with end-stage kidney disease. Thus, early detection of the cause of impaired cardiopulmonary function in patients undergoing peritoneal dialysis (PD) is of important clinical significance. In this cross-sectional study, symptom-restricted cardiopulmonary exercise testing (CPET) was performed in 30 patients undergoing PD and in 23 age- and sex-matched healthy control subjects. A fixed workload was added every minute until fatigue, and breath-by-breath respiratory gas was analysed with an automated gas analyzer at 10-s intervals. The peak oxygen uptake (16.39 ± 0.83 vs. 25.77 ± 1.33 ml/kg/min p < 0.001) and the oxygen uptake at the anerobic threshold of patients undergoing PD (9.61 ± 0.34 vs. 14.55 ± 0.64 ml/kg/min; p < 0.001) were lower than in healthy control subjects, and both of these parameters correlated with body mass index and left atrial dimension. A steeper minute ventilation/carbon dioxide production slope (27.20 ± 0.68 vs. 24.29 ± 0.69；p < 0.01) and a lower end-tidal carbon dioxide partial pressure (37.93 ± 0.54 vs. 41.27 ± 0.83 mmHg；p < 0.05) were observed in patients undergoing PD. The oxygen pulse and oxygen uptake efficiency slope was smaller in patients undergoing PD. The Maximum heart rate (126.07 ± 4.01 vs. 149.96 ± 5.29 bpm；p < 0.01) and 1-min heart rate recovery (13.93 ± 1.52 vs. 24.39 ± 1.61 bpm；p < 0.01) were also lower in patients undergoing PD. Subclinical cardiopulmonary dysfunction may exist in patients with PD, and a reduction in CRF in patients undergoing PD is affected by both central and peripheral functions. CPET has potential value in revealing the mechanism of impaired CRF and in discovering subclinical abnormalities in cardiopulmonary function.

Boosting framework via clinical monitoring data to predict the depth of anesthesia.

BACKGROUND: Prediction of the depth of anesthesia is a difficult job in the biomedical field.OBJECTIVE: This study aimed to build a boosting-based prediction model to predict the depth of anesthesia based on four clinical monitoring data.METHODS: Boosting is a framework algorithm that is used to train a series of weak learners into strong learners by assigning different weights according to their classification accuracy. The input of the boosting-based prediction model included four types of clinical monitoring data: electromyography, end-tidal carbon dioxide partial pressure, remifentanil dosage, and flow rate. The output was the depth of anesthesia.RESULTS: The boosting framework model built in this study achieved higher prediction accuracy and a lower discrete degree in predicting the depth of anesthesia compared with the DT-, KNN-, and SVM-based models.CONCLUSIONS: The boosting framework was used to set up a prediction model to predict the depth of anesthesia based on four clinical monitoring data. In the experiments, the boosting framework model of this study achieved higher prediction accuracy and a lower discrete degree. This model will be useful in predicting the depth of anesthesia.