Six methods to determine expiratory time constants in mechanically ventilated patients: a prospective observational physiology study.

BACKGROUND: Expiratory time constant (τ) objectively assesses the speed of exhalation and can guide adjustments of the respiratory rate and the I:E ratio with the goal of achieving complete exhalation. Multiple methods of obtaining τ are available, but they have not been compared. The purpose of this study was to compare six different methods to obtain τ and to test if the exponentially decaying flow corresponds to the measured time constants. METHODS: In this prospective study, pressure, flow, and volume waveforms of 30 postoperative patients undergoing volume (VCV) and pressure-controlled ventilation (PCV) were obtained using a data acquisition device and analyzed. τ was measured as the first 63% of the exhaled tidal volume (VT) and compared to the calculated τ as the product of expiratory resistance (RE) and respiratory system compliance (CRS), or τ derived from passive flow/volume waveforms using previously published equations as proposed by Aerts, Brunner, Guttmann, and Lourens. We tested if the duration of exponentially decaying flow during exhalation corresponded to the duration of the predicted second and third τ, based on multiples of the first measured τ. RESULTS: Mean (95% CI) measured τ was 0.59 (0.57-0.62) s and 0.60 (0.58-0.63) s for PCV and VCV (p = 0.45), respectively. Aerts method showed the shortest values of all methods for both modes: 0.57 (0.54-0.59) s for PCV and 0.58 (0.55-0.61) s for VCV. Calculated (CRS * RE) and Brunner's τ were identical with mean τ of 0.64 (0.61-0.67) s for PCV and 0.66 (0.63-069) s for VCV. Mean Guttmann's τ was 0.64 (0.61-0.68) in PCV and 0.65 (0.62-0.69) in VCV. Comparison of each τ method between PCV and VCV was not significant. Predicted time to exhale 95% of the VT (i.e., 3*τ) was 1.77 (1.70-1.84) s for PCV and 1.80 (1.73-1.88) s for VCV, which was significantly longer than measured values: 1.27 (1.22-1.32) for PCV and 1.30 (1.25-1.35) s for VCV (p < 0.0001). The first, the second and the third measured τ were progressively shorter: 0.6, 0.4 and 0.3 s, in both ventilation modes (p < 0.0001). CONCLUSION: All six methods to determine τ show similar values and are feasible in postoperative mechanically ventilated patients in both PCV and VCV modes.

European anesthesiologists' experiences with gender-based mistreatment in the workplace: a secondary multilevel regression analysis.

BACKGROUND: Workplace gender-based mistreatment (GBM) refers to negative or harmful behaviors directed towards employees. In healthcare settings, this can lead to job dissatisfaction and underperformance and potentially compromise patient outcomes. The aim of this study was to examine workplace GBM among European anesthesiologists and produce the first European Gender-based Mistreatment Rank in Anesthesiology. METHODS: We conducted a secondary analysis from a worldwide cross-sectional survey database consisting of a 46-item questionnaire exploring, among other outcomes, gender bias attributable to workplace attitudes. The survey completion rate was 80.8%. All respondents were selected from European countries. Associations between mistreatment and the remaining variables were analyzed using univariate and multivariate logistic regression analyses. A generalized linear mixed model was then used to quantify the impact of mistreatment in each European country. Statistical significance was set at P < 0.05. RESULTS: This study included 5,795 respondents from 43 European countries. The independent predictors of GBM were as follows: female gender, younger age, perceiving gender as a disadvantage for leadership, and perceiving gender as a disadvantage for research. The full model was statistically significant, indicating an ability to distinguish between those who experienced GBM and those who did not (P < 0.001). Thus, 26 European countries were ranked based on the prevalence of mistreatment, with Italy showing the best performance (lowest prevalence). CONCLUSIONS: The aim of our study was to provide preliminary insight into GBM in anesthesiology in Europe, function as a key benchmark for gender equity, and chart the evolution of disparities over time.

Endothelial Dysfunction in Patients Undergoing Cardiac Surgery: A Narrative Review and Clinical Implications.

Cardiac surgery is one of the highest-risk procedures, usually involving cardiopulmonary bypass and commonly inducing endothelial injury that contributes to the development of perioperative and postoperative organ dysfunction. Substantial scientific efforts are being made to unravel the complex interaction of biomolecules involved in endothelial dysfunction to find new therapeutic targets and biomarkers and to develop therapeutic strategies to protect and restore the endothelium. This review highlights the current state-of-the-art knowledge on the structure and function of the endothelial glycocalyx and mechanisms of endothelial glycocalyx shedding in cardiac surgery. Particular emphasis is placed on potential strategies to protect and restore the endothelial glycocalyx in cardiac surgery. In addition, we have summarized and elaborated the latest evidence on conventional and potential biomarkers of endothelial dysfunction to provide a comprehensive synthesis of crucial mechanisms of endothelial dysfunction in patients undergoing cardiac surgery, and to highlight their clinical implications.

A way forward in pulmonary aspiration incidence reduction: ultrasound, mathematics, and worldwide data collection

Abstract Aspiration of gastric contents during induction of general anesthesia remains a significant cause of mortality and morbidity in anesthesia. Recent data show that pulmonary aspiration still accounts for many cases with implications on mortality despite technical and technological evolution. Practical, ethical, and methodological issues prevent high-quality research in the setting of aspiration and rapid sequence induction/intubation, and significant controversy is ongoing. Patients' position, drugs choice, dosing and timing, use of cricoid force, and a reliable risk assessment are widely debated with significant questions still unanswered. We focus our discussion on three approaches to promote a better understanding of rapid sequence induction/intubation and airway management decision-making. Firstly, we review how we can use qualitative and quantitative assessment of fasting status and gastric content with the point-of-care ultrasound as an integral part of preoperative evaluation and planning. Secondly, we propose using imaging-based mathematical models to study different patient positions and aspiration mechanisms, including identifying aspiration triggers. Thirdly, we promote the development of a global data collection system aiming to obtain precise epidemiological data. Therefore, we fill the gap between evidence-based medicine and experts' opinion through easily accessible and diffused computer-based databases. A better understanding of aspiration epidemiology obtained through focused global data gathering systems, the widespread use of ultrasound-based prandial status evaluation, and development of advanced mathematical models might potentially guide safer airway management decision making in the 21st century.

A way forward in pulmonary aspiration incidence reduction: ultrasound, mathematics, and worldwide data collection.

Aspiration of gastric contents during induction of general anesthesia remains a significant cause of mortality and morbidity in anesthesia. Recent data show that pulmonary aspiration still accounts for many cases with implications on mortality despite technical and technological evolution. Practical, ethical, and methodological issues prevent high-quality research in the setting of aspiration and rapid sequence induction/intubation, and significant controversy is ongoing. Patients' position, drugs choice, dosing and timing, use of cricoid force, and a reliable risk assessment are widely debated with significant questions still unanswered. We focus our discussion on three approaches to promote a better understanding of rapid sequence induction/intubation and airway management decision-making. Firstly, we review how we can use qualitative and quantitative assessment of fasting status and gastric content with the point-of-care ultrasound as an integral part of preoperative evaluation and planning. Secondly, we propose using imaging-based mathematical models to study different patient positions and aspiration mechanisms, including identifying aspiration triggers. Thirdly, we promote the development of a global data collection system aiming to obtain precise epidemiological data. Therefore, we fill the gap between evidence-based medicine and experts' opinion through easily accessible and diffused computer-based databases. A better understanding of aspiration epidemiology obtained through focused global data gathering systems, the widespread use of ultrasound-based prandial status evaluation, and development of advanced mathematical models might potentially guide safer airway management decision making in the 21st century.

Determining respiratory rate using measured expiratory time constant: A prospective observational study.

PURPOSE: Potential negative implications associated with high respiratory rate (RR) are intrinsic positive end-expiratory pressure (PEEPi) generation, cardiovascular depression and possibly ventilator induced lung injury. Despite these negative consequences, optimal RR remains largely unknown. We hypothesized that without consideration of dynamics of lung emptying (i.e., the expiratory time constant [RCEXP]) clinician settings of RR may exceed the frequency needed for optimal lung emptying. MATERIALS AND METHODS: This prospective multicenter observational study measured RCEXP in 56 intensive care patients receiving pressure-controlled ventilation. We compared set RR to the one predicted with RCEXP (RRP). Also, the subgroup of patients with prolonged RCEXP was analyzed. RESULTS: Overall, the absolute mean difference between the set RR and RRP was 2.8 bpm (95% CI: 2.3-3.2). Twenty-nine (52%) patients had prolonged RCEXP (>0.8 s), mean difference between set RR and RRP of 3.1 bpm (95% CI: 2.3-3.8; p < 0.0001) and significantly higher PEEPi compared to those with RCEXP ≤ 0.8 s: 4.4 (95% CI: 3.6-5.2) versus 1.5 (95% CI: 0.9-2.0) cmH2O respectively, p < 0.0001. CONCLUSIONS: Use of RRP based on measured RCEXP revealed that the clinician-set RR exceeded that predicted by RCEXP in the majority of patients. Measuring RCEXP appears to be a useful variable for adjusting the RR during mandatory mechanical ventilation.

Welfare practices for anaesthesiology trainees in Europe: A descriptive cross-sectional survey study.

BACKGROUND: Current regulations of anaesthesiology training programmes may affect gender equity, female representation and leadership. OBJECTIVE: To describe the work regulations of anaesthesiology training programs and working conditions during the early period of child-rearing in European countries. DESIGN: Cross-sectional survey. SETTING: National Anesthesiologists Societies Committee (NASC) representatives of the European Society of Anesthesiology and Intensive Care. PARTICIPANTS: Thirty-eight NASC representatives. MAIN OUTCOME MEASURES: Basic specialist training working conditions, gender-related data, return to work after childbirth and workplace policies against discrimination during anaesthesiology specialist training. INTERVENTIONS: A 48-item questionnaire to explore the work patterns and conditions for trainees especially for new parents, professional development opportunities and work discrimination regulations in each representative country was distributed to NASC representatives of 44 European countries. RESULTS: We collected the replies of each representative (38 representatives from 44 invited countries' representatives, 86% response rate). The median [IQR] proportion of female trainees was 60% [50 to 68]. There were no reported pay differences between sexes. In eight European countries, pregnant trainees worked fewer hours and were excused from night shifts. Women could not be laid off during pregnancy in all 38 countries (100%). The countries offered a median of 18 weeks of paid (total or partial) maternity leave (range, 13 to 60 weeks). Most countries (89%) accommodate paid paternity leaves. A significant proportion of parental leave was unpaid ( n =18, 42%). Twenty-one (55%) countries allowed part-time work after delivery. The UK was the only country with clear recommendations to formally complain after harassment. CONCLUSION: European countries have a wide variety of regulations. On paper, numerous countries have various paid maternal, paternal and parental leave; however, it remains to be determined if such leave takes place in practice. The practical consequences of these regulations on female trainees during the child-rearing period need to be explored further. TRIAL REGISTRATION: None.

Time constant to determine PEEP levels in mechanically ventilated COVID-19 ARDS: a feasibility study.

BACKGROUND: We hypothesized that the measured expiratory time constant (TauE) could be a bedside parameter for the evaluation of positive end-expiratory pressure (PEEP) settings in mechanically ventilated COVID-19 patients during pressure-controlled ventilation (PCV). METHODS: A prospective study was conducted including consecutively admitted adults (n = 16) with COVID-19-related ARDS requiring mechanical ventilation. A PEEP titration using PCV with a fixed driving pressure of 14 cmH2O was performed and TauE recorded at each PEEP level (0 to 18 cmH2O) in prone (n = 29) or supine (n = 24) positions. The PEEP setting with the highest TauE (TauEMAX) was considered to represent the best tradeoff between recruitment and overdistention. RESULTS: Two groups of patterns were observed in the TauE plots: recruitable (R) (75%) and nonrecruitable (NR) (25%). In the R group, the optimal PEEP and PEEP ranges were 8 ± 3 cmH2O and 6-10 cmH2O for the prone position and 9 ± 3 cmH2O and 7-12 cmH2O for the supine position. In the NR group, the optimal PEEP and PEEP ranges were 4 ± 4 cmH2O and 1-8 cmH2O for the prone position and 5 ± 3 cmH2O and 1-7 cmH2O for the supine position, respectively. The R group showed significantly higher optimal PEEP (p < 0.004) and PEEP ranges (p < 0.001) than the NR group. Forty-five percent of measurements resulted in the most optimal PEEP being significantly different between the positions (p < 0.01). Moderate positive correlation has been found between TauE vs CRS at all PEEP levels (r2 = 0.43, p < 0.001). CONCLUSIONS: TauE may be a novel method to assess PEEP levels. There was wide variation in patient responses to PEEP, which indicates the need for personalized evaluation.

Programmed multi-level ventilation in COVID-19-related acute respiratory distress syndrome: a multi-center retrospective observational study.

OBJECTIVE: We evaluated pressure-controlled ventilation (PCV) with multiple programmed levels of positive end expiratory pressure (programmed multi-level ventilation; PMLV) in patients with coronavirus disease 2019 (COVID-19)-related acute respiratory distress syndrome (ARDS). METHODS: We conducted a multicenter, retrospective study from November 2020 to February 2021. PMLV was used with PCV in all patients with intensive care admission until improvement in oxygenation (fraction of inspired oxygen [FiO2] ≤0.50 and oxygen saturation [SpO2] >92%). The observed outcomes were improvement of hypoxemia, length of mechanical ventilation, partial pressure of carbon dioxide (PaCO2) stability, and adverse events. RESULTS: Of 188 mechanically ventilated patients with COVID-19-related ARDS, we analyzed 60 patients treated with PMLV. Hypoxemia improved in 55 (92%) patients, as measured by the change in partial pressure of oxygen/FiO2 and SpO2/FiO2 ratios on day 3 versus day 1, and in 32 (66%) ventilated patients on day 7 versus day 3. The median (interquartile range) length of mechanical ventilation for survivors and non-survivors was 8.4 (4.7-14.9) and 6.7 (3.6-10.3) days, respectively. CONCLUSIONS: PMLV appears to be a safe and effective ventilation strategy for improving hypoxemia in patients with COVID-19-related ARDS. Further studies are needed comparing the PMLV mode with the conventional ARDS ventilatory approach.

On pandemics and pivots: a COVID-19 reflection on envisioning the future of medical education.

The required adjustments precipitated by the coronavirus disease 2019 crisis have been challenging, but also represent a critical opportunity for the evolution and potential disruptive and constructive change of medical education. Given that the format of medical education is not fixed, but malleable and in fact must be adaptable to societal needs through ongoing reflexivity, we find ourselves in a potentially transformative learning phase for the field. An Association for Medical Education in Europe ASPIRE Academy group of 18 medical educators from seven countries was formed to consider this opportunity, and identified critical questions for collective reflection on current medical education practices and assumptions, with the attendant challenge to envision the future of medical education. This was achieved through online discussion as well as asynchronous collective reflections by group members. Four major themes and related conclusions arose from this conversation: Why we teach: the humanitarian mission of medicine should be reinforced; what we teach: disaster management, social accountability and embracing an environment of complexity and uncertainty should be the core; how we teach: open pathways to lean medical education and learning by developing learners embedded in a community context; and whom we teach: those willing to take professional responsibility. These collective reflections provide neither fully matured digests of the challenges of our field, nor comprehensive solutions; rather they are offered as a starting point for medical schools to consider as we seek to harness the learning opportunities stimulated by the pandemic.

Correction: Scientific quality of COVID-19 and SARS CoV-2 publications in the highest impact medical journals during the early phase of the pandemic: A case control study.

[This corrects the article DOI: 10.1371/journal.pone.0241826.].

Effects of the reservoir bag disconnection on inspired gases during general anesthesia: a simulator-based study.

BACKGROUND: Fresh gas decoupling is a feature of the modern anesthesia workstation, where the fresh gas flow (FGF) is diverted into the reservoir bag and is not added to the delivered tidal volume, which thus remains constant. The present study aimed to investigate the entraining of the atmospheric air into the anesthesia breathing circuit in case the reservoir bag was disconnected. METHODS: We conducted a simulator-based study, where the METI HPS simulator was connected to the anesthesia workstation. The effect of the disconnected reservoir bag was evaluated using oxygen (O2) and air or oxygen and nitrous oxide (N2O) as a carrier gas at different FGF rates. We disconnected the reservoir bag for 10 min during the maintenance phase. We recorded values for inspiratory O2, N2O, and sevoflurane. The time constant of the exponential process was estimated during reservoir bag disconnection. RESULTS: The difference of O2, N2O and sevoflurane concentrations, before, during, and after reservoir bag disconnection was statistically significant at 0.5, 1, and 2 L/min of FGF (p < 0.001). The largest decrease of the inspired O2 concentrations (FIO2) was detected in the case of oxygen and air as the carrier gas and an FGF of 1 L/min, when oxygen decreased from median [25th-75th percentile] 55.00% [54.00-56.00] to median 39.50% [38.00-42.50] (p < 0.001). The time constant for FIO2 during reservoir bag disconnection in oxygen and air as the carrier gas, were median 2.5, 2.5, and 1.5 min in FGF of 0.5, 1.0, and 2 L/min respectively. CONCLUSIONS: During the disconnection of the anesthesia reservoir bag, the process of pharmacokinetics takes place faster compared to the wash-in and wash-out pharmacokinetic properties in the circle breathing system. The time constant was affected by the FGF rate, as well as the gradient of anesthetic gases between the anesthesia circle system and atmospheric air.

The Clinical Use of Cricoid Pressure: First, Do No Harm.

Application of cricoid pressure (CP) during rapid sequence induction and intubation sequence has been a "standard" of care for many decades, despite limited scientific proof of its efficacy in preventing pulmonary aspiration of gastric contents. While some of the current rapid sequence induction and intubation guidelines recommend its use, other international guidelines do not, and many clinicians argue that there is insufficient evidence to either continue or abandon its use. Recently published articles and accompanying editorials have reignited the debate on the efficacy and safety of CP application and have generated multiple responses that pointed out the various (and significant) limitations of the available evidence. Thus, a critical discussion of available data must be undertaken before making a final clinical decision on such an important patient safety issue. In this review, the authors will take an objective look at the available scientific evidence about the effectiveness and safety of CP in patients at risk of pulmonary aspiration of gastric contents. We suggest that current data are inadequate to impose clinical guidelines on the use of CP because we acknowledge that currently there is not, and there may never be, a method to prevent aspiration in all patients. In addition, we reiterate that a universally accepted medical-legal standard for approaching the high-risk aspiration patient does not exist, discuss the differences in practice between the US and international practitioners regarding use of CP, and propose 5 recommendations on how future studies might be designed to obtain optimal scientific evidence about the effectiveness and safety of CP in patients at risk for pulmonary aspiration.

Scientific quality of COVID-19 and SARS CoV-2 publications in the highest impact medical journals during the early phase of the pandemic: A case control study.

BACKGROUND: A debate about the scientific quality of COVID-19 themed research has emerged. We explored whether the quality of evidence of COVID-19 publications is lower when compared to nonCOVID-19 publications in the three highest ranked scientific medical journals. METHODS: We searched the PubMed Database from March 12 to April 12, 2020 and identified 559 publications in the New England Journal of Medicine, the Journal of the American Medical Association, and The Lancet which were divided into COVID-19 (cases, n = 204) and nonCOVID-19 (controls, n = 355) associated content. After exclusion of secondary, unauthored, response letters and non-matching article types, 155 COVID-19 publications (including 13 original articles) and 130 nonCOVID-19 publications (including 52 original articles) were included in the comparative analysis. The hierarchical level of evidence was determined for each publication included and compared between cases and controls as the main outcome. A quantitative scoring of quality was carried out for the subgroup of original articles. The numbers of authors and citation rates were also compared between groups. RESULTS: The 130 nonCOVID-19 publications were associated with higher levels of evidence on the level of evidence pyramid, with a strong association measure (Cramer's V: 0.452, P <0.001). The 155 COVID-19 publications were 186-fold more likely to be of lower evidence (95% confidence interval [CI] for odds ratio, 7.0-47; P <0.001). The quantitative quality score (maximum possible score, 28) was significantly different in favor of nonCOVID-19 (mean difference, 11.1; 95% CI, 8.5-13.7; P <0.001). There was a significant difference in the early citation rate of the original articles that favored the COVID-19 original articles (median [interquartile range], 45 [30-244] vs. 2 [1-4] citations; P <0.001). CONCLUSIONS: We conclude that the quality of COVID-19 publications in the three highest ranked scientific medical journals is below the quality average of these journals. These findings need to be verified at a later stage of the pandemic.

A prospective randomized controlled study of combined spinal-general anesthesia vs. general anesthesia for laparoscopic gynecological surgery: Opioid sparing properties.

STUDY OBJECTIVE: We aimed to determine the magnitude of peri-operative opioid sparing effect when general anesthesia is combined with spinal analgesia for laparoscopic gynecological surgery. DESIGN: A prospective randomized controlled study; a three-group trial with two comparisons (each intervention group to control). SETTING: Operating room and postoperative recovery area. PATIENTS: Patients aged between 18 and 65 years with American Society of Anesthesiologists physical status 1 or 2 who were scheduled for inpatient elective laparoscopic gynecological surgery with expected pneumoperitoneum duration of at least 20 min. Of 102 randomized patients, 99 completed the study. INTERVENTIONS: Patients were randomized to general anesthesia alone (control group) or combined with very-low-dose (levobupivacaine 3.75 mg; sufentanil 2.5 µg) or low-dose (levobupivacaine 7.5 mg; sufentanil 2.5 µg) spinal analgesia. MEASUREMENTS: Primary endpoints were perioperative opioid consumption and pain scores (11-point numeric rating scale) at 30 min, 1 h, 2 h, 4 h and 24 h post-surgery. Secondary endpoints were patient satisfaction with anesthetic care and participation in research, sevoflurane consumption and adverse effects. MAIN RESULTS: Intra-operative sufentanil (median [95% CI]) consumption was 16.1 (10.5-22.6) µg/h in the control group versus 4.7 (3.2-9.2) µg/h in the very-low-dose and versus 2.9 (0.0-4.0) µg/h in the low-dose spinal analgesia groups (p < 0.001, for both comparisons). Median (95% CI) piritramide consumption at 24 h post-surgery was 7.5 (3-8) mg in the control group versus 5 (0-7.5) mg in the very-low dose spinal analgesia group (p = 0.182) and versus 2 (0-2.5) mg in the low-dose spinal analgesia group (p = 0.001). Postoperative pain scores were consistently <3 only in the low dose spinal analgesia group. Patient satisfaction with anesthetic care and participation in research was very high in all groups. CONCLUSIONS: Low-dose spinal analgesia in combination with general anesthesia reduces peri-operative opioid consumption in laparoscopic gynecological surgery in immediate postoperative period.

Perceptions of gender equity in departmental leadership, research opportunities, and clinical work attitudes: an international survey of 11 781 anaesthesiologists.

BACKGROUND: Women make up an increasing proportion of the physician workforce in anaesthesia, but they are consistently under-represented in leadership and governance. METHODS: We performed an internet-based survey to investigate career opportunities in leadership and research amongst anaesthesiologists. We also explored gender bias attributable to workplace attitudes and economic factors. The survey instrument was piloted, translated into seven languages, and uploaded to the SurveyMonkey® platform. We aimed to collect between 7800 and 13 700 responses from at least 100 countries. Participant consent and ethical approval were obtained. A quantitative analysis was done with χ2 and Cramer's V as a measure of strength of associations. We used an inductive approach and a thematic content analysis for qualitative data on current barriers to leadership and research. RESULTS: The 11 746 respondents, 51.3% women and 48.7% men, represented 148 countries; 35 respondents identified their gender as non-binary. Women were less driven to achieve leadership positions (P<0.001; Cramer's V: 0.11). Being a woman was reported as a disadvantage for leadership and research (P<0.001 for both; Cramer's V: 0.47 and 0.34, respectively). Women were also more likely to be mistreated in the workplace (odds ratio: 10.6; 95% confidence interval: 9.4-11.9; P<0.001), most commonly by surgeons. Several personal, departmental, institutional, and societal barriers in leadership and research were identified, and strategies to overcome them were suggested. Lower-income countries were associated with a significantly smaller gender gap (P<0.001). CONCLUSIONS: Whilst certain trends suggest improvements in the workplace, barriers to promotion of women in key leadership and research positions continue within anaesthesiology internationally.