Peak Inspiratory Pressure Research Articles

Influence of different head and neck positions on performance characteristics of second generation supraglottic airway devices

BackgroundVarious head and neck positions alter the performance of supraglottic airway devices (SAD). We compared the influence of flexion, extension, neutral and rotation of the neck on performance characteristics of second generation airway devices namely Proseal (PLMA), i-gel and Auragain laryngeal mask. MethodsThis study was conducted in 90 ASA physical status I and II patients 18–65 years of age. Patients were randomised into three groups with 30 patients in each: PLMA, i-gel and Auragain. The primary objective was to compare oropharyngeal leak pressure (OPLP) among PLMA, i-gel and Auragain in neutral, flexion, extension and lateral rotation of the neck. The secondary objective was to compare Peak inspiratory pressure (PIP), ventilation score, expired tidal volume, fiberoptic grading of laryngeal view, end tidal carbon dioxide and OPLP-PIP difference. ResultsPLMA, i-gel and Auragain have the highest OPLP in flexion (34.4 ± 2.5, 31.6 ± 2.3, 32.8 ± 1.7) followed by neutral, left lateral rotation and lowest in extension (26.7 ± 1.6, 25.4 ± 3.19, 29.6 ± 1.0) respectively. PLMA and Auragain have significantly higher OPLP when compared to i-gel in all positions p < 0.05. In extension, OPLP with Auragain (29.6 + 1.0) was significantly higher than PLMA (26.7 + 1.6) and i-gel (25.4 + 3.1), p < 0.001. PIP was significantly higher in flexion position for all the three devices. No significant difference in fibre optic grading and ventilation score was seen for three devices in various neck positions. ConclusionsPLMA and Auragain have better sealing pressure than i-gel in all the positions. Flexion position during surgery is best for maintaining OPLP. Auragain should be preferred over PLMA and i-gel in surgeries involving extension of neck.

Intraoperative mechanical power and postoperative pulmonary complications in low-risk surgical patients: a prospective observational cohort study

BackgroundInadequate intraoperative mechanical ventilation (MV) can lead to ventilator-induced lung injury and increased risk for postoperative pulmonary complications (PPCs). Mechanical power (MP) was shown to be a valuable indicator for MV outcomes in critical care patients. The aim of this study is to assess the association between intraoperative MP in low-risk surgical patients undergoing general anesthesia and PPCs.MethodsTwo-hundred eighteen low-risk surgical patients undergoing general anesthesia for elective surgery were included in the study. Intraoperative mechanical ventilatory support parameters were collected for all patients. Postoperatively, patients were followed throughout their hospital stay and up to seven days post discharge for the occurrence of any PPCs.ResultsOut of 218 patients, 35% exhibited PPCs. The average body mass index, tidal volume per ideal body weight, peak inspiratory pressure, and MP were significantly higher in the patients with PPCs than in the patients without PPCs (30.3 ± 8.1 kg/m2 vs. 26.8 ± 4.9 kg.m2, p < 0.001; 9.1 ± 1.9 ml/kg vs. 8.6 ± 1.4 ml/kg, p = 0.02; 20 ± 4.9 cmH2O vs. 18 ± 3.7 cmH2O, p = 0.001; 12.9 ± 4.5 J/min vs. 11.1 ± 3.7 J/min, p = 0.002). A multivariable regression analysis revealed MP as the sole significant predictor for the risk of postoperative pulmonary complications [OR 1.1 (95% CI 1.0–1.2, p = 0.036].ConclusionsHigh intraoperative mechanical power is a risk factor for developing postoperative pulmonary complications. Furthermore, intraoperative mechanical power is superior to other traditional mechanical ventilation variables in identifying surgical patients who are at risk for developing postoperative pulmonary complications.Clinical trial registration NCT03551899; 24/02/2017.

Comparison of nasal and face mask ventilation in anaesthetised obese adults: A randomised controlled study.

The use of a face mask while inducing general anaesthesia (GA) in obese patients is often ineffective in providing adequate ventilation. Although nasal mask ventilation has demonstrated effectiveness for continuous positive airway pressure (CPAP) in obese patients with obstructive sleep apnoea (OSA), it has not yet been applied to the induction of anaesthesia. This study evaluated the efficacy of nasal mask ventilation against standard face mask ventilation in anaesthetised obese patients with body mass index (BMI)>25 kg/m2. Ninety adult patients with BMI >25 kg/m2 were randomly assigned to receive either facemask (Group FM) or nasal-mask (Group NM) ventilation during induction of GA. Expired tidal volume (VtE), air leak, peak inspiratory pressure (PIP), plateau pressure (PPLAT), oxygen saturation (SpO2), and end-tidal carbon dioxide (EtCO2) were recorded for10 breaths, and their mean was analysed. The mean (standard deviation) VtE measured was not significantly higher in Group NM [455.98 (55.64) versus 436.90 (49.50) mL, P = 0.08, degree of freedom (df):88, mean difference (95% confidence interval [CI]) -19.08 (-41.14, 2.98) mL]. Mean air-leak [16.44 (22.16) versus 31.63 (21.56) mL, P = 0.001, df: 88, mean difference 95%CI: 15.19 (6.03,24.35)], mean PIP [14.79 (1.39) versus 19.94 (3.05) cmH2O, P = 0.001, df: 88, mean difference, 95%CI: 5.15 (4.16, 6.14)], and mean PPLAT [12.04 (1.21) versus 16.66 (2.56) cmH2O, P = 0.001, df: 88, mean difference 95% CI: 4.62 (3.78, 5.45)] were significantly lower in Group NM. EtCO2, SpO2, and haemodynamic measurements were similar between the two groups. Nasal mask ventilation is an effective ventilation method and can be used as an alternative to face mask ventilation in anaesthetised obese adults with BMI>25 kg/m2.

Recapitulation of human pathophysiology and identification of forensic biomarkers in a translational model of chlorine inhalation injury.

Chlorine gas (Cl2) has been repeatedly used as a chemical weapon, first in World War I and most recently in Syria. Life-threatening Cl2 exposures frequently occur in domestic and occupational environments, and in transportation accidents. Modeling the human etiology of Cl2-induced acute lung injury (ALI), forensic biomarkers, and targeted countermeasures development have been hampered by inadequate large animal models. The objective of this study was to develop a translational model of Cl2-induced ALI in swine to understand toxico-pathophysiology and evaluate whether it is suitable for screening potential medical countermeasures and to identify biomarkers useful for forensic analysis. Specific pathogen-free Yorkshire swine (30-40 kg) of either sex were exposed to Cl2 (≤240 ppm for 1 h) or filtered air under anesthesia and controlled mechanical ventilation. Exposure to Cl2 resulted in severe hypoxia and hypoxemia, increased airway resistance and peak inspiratory pressure, and decreased dynamic lung compliance. Cl2 exposure resulted in increased total leucocyte and neutrophil counts in bronchoalveolar lavage fluid, vascular leakage, and pulmonary edema compared with the air-exposed group. The model recapitulated all three key histopathological features of human ALI, such as neutrophilic alveolitis, deposition of hyaline membranes, and formation of microthrombi. Free and lipid-bound 2-chlorofatty acids and chlorotyrosine-modified proteins (3-chloro-l-tyrosine and 3,5-dichloro-l-tyrosine) were detected in plasma and lung tissue after Cl2 exposure. In this study, we developed a translational swine model that recapitulates key features of human Cl2 inhalation injury and is suitable for testing medical countermeasures, and validated chlorinated fatty acids and protein adducts as biomarkers of Cl2 inhalation.NEW & NOTEWORTHY We established a swine model of chlorine gas-induced acute lung injury that exhibits several features of human acute lung injury and is suitable for screening potential medical countermeasures. We validated chlorinated fatty acids and protein adducts in plasma and lung samples as forensic biomarkers of chlorine inhalation.

Development of an experimental technique for orthotopic left lung transplantation in a rabbit model

Objective: to develop, master and evaluate the efficiency of an isolated lung transplantation (LT) technique on a rabbit animal model using Perfadex Plus® solution for cold static storage. Materials and methods. Scottish Giant rabbits (n = 20) were used in this study and divided into two groups: donors and recipients. Donor lungs were preserved with Perfadex Plus® solution and stored for 6 hours at 4 °C. Recipient animals underwent unilateral orthotopic left LT. The postoperative follow-up period was 24 hours. Laboratory and instrumental control with assessment of blood gas composition, lactate level, ventilation parameters, and central hemodynamic parameters, was performed during the follow-up. Chest X-ray in direct projection was performed twice, and at the end of follow-up, material was taken for histologic examination. Results. We obtained a high oxygenation index in the post-transplant period (&gt;350 at p &lt; 0.023), as well as physiological indicators of lactate (3 ± 0.3 mmol/L at p &lt; 0.002) and peak inspiratory pressure (15 ± 1 cmH2O, p &lt; 0.001). Radiological examination showed no radiological signs of severe primary graft dysfunction in all cases (mean RALE score 1), which was confirmed by histological studies. Conclusion. Left LT in rabbits is possible, the LT technique on a biological rabbit model using Perfadex Plus® solution is valid and efficient with the achievement of satisfactory gas exchange, ventilation and metabolism parameters.

Effect of Sildenafil in Neonates with Persistent Pulmonary Hypertension: An Interventional Study

Introduction: Persistent Pulmonary Hypertension of the Newborn (PPHN) reflects a disruption of the normal perinatal circulatory transition and is characterised by high pulmonary artery pressure. Inhaled Nitric Oxide (iNO) is considered the mainstay of treatment for PPHN. However, many developing and resource limited countries do not have access to such expensive therapy. Therefore, sildenafil, due to its easy availability and low cost, becomes the most commonly used drug in the management of PPHN in such settings. Aim: To study the treatment response and outcomes of neonates who received sildenafil for the management of PPHN. Materials and Methods: The present hospital-based prospective interventional study was conducted in the Neonatal Intensive Care Unit (NICU), BJ Medical College, Civil Hospital, Ahmedabad, Gujarat, between May 1, 2020, and April 30, 2021. Study was conducted on neonates with meconium aspiration syndrome and/or severe birth asphyxia admitted to the NICU. A total of 48 neonates with Two Dimensional (2D) echocardiography-proven PPHN were enrolled. Baseline clinical parameters including heart rate, respiratory rate, preductal and postductal Saturation of Peripheral Oxygen (SpO2), Oxygenation Index (OI), Saturation Oxygen Distending Pressure Index (SOPI), and Non Invasive Blood Pressure (NIBP) were monitored every six hours. Neonates who were on invasive/ non invasive ventilation had their Fraction of Inspired Oxygen (FiO2), Positive End Expiratory Pressure (PEEP), Peak Inspiratory Pressure (PIP), respiratory rate and flow rate monitored every six hours. Data were statistically analysed using Analysis of Variance (ANOVA) test. Results: During the study period, a total of 1080 neonates were admitted with meconium aspiration syndrome and/or severe birth asphyxia, out of which 48 neonates showed findings suggestive of PPHN on 2D echocardiography. A statistically significant improvement in oxygenation after sildenafil treatment was indicated by a significant reduction in OI from 35.3±8.6 to 13.2±2.1 (p-value&lt;0.001), a reduction in SOPI from 3.6±0.3 to 1.5±0.2 (p-value&lt;0.001), a reduction in FiO2 (%) from 94.6±8.19 to 24.2±4.5 (p-value&lt;0.001), an increase in Partial pressure of oxygen (PaO2) (mmHg) from 52±5.6 to 72±3.4 (p-value&lt;0.001), and an increase in SpO2 (%) from 83.5±8.6 to 93.5±5.1 (p-value&lt;0.001). Conclusion: The findings of the present study suggest that oral sildenafil can be successfully used to improve oxygenation in patients with PPHN, especially in a resource limited setting where facilities like Extracorporeal Membrane Oxygenation (ECMO) and iNO are not available, as demonstrated in the present study.

Clinical Profile and Outcome of Moderate to Severe Acute Respiratory Distress Syndrome in a Paediatric Intensive Care Unit of Eastern India: A Prospective Cohort Study

Introduction: Paediatric Acute Respiratory Distress Syndrome (PARDS) remains a major cause of mortality and morbidity in Paediatric Intensive Care Units (PICU) despite various advanced management strategies. The management and outcome of PARDS depend on the severity of the disease. Aim: To study the clinical profile in terms of aetiology and outcome of paediatric patients with moderate to severe Acute Respiratory Distress Syndrome (ARDS) in the PICU. Materials and Methods: A prospective cohort study was conducted at the PICU in Dr. BC Roy Postgraduate Institute of Paediatric Sciences, Kolkata, West Bengal, India, from July 2018 to June 2019. A total of 120 children aged between two months and 12 years who developed moderate to severe ARDS according to Paediatric Acute Lung Injury Consensus Conference (PALICC) criteria were included. Demographic details, different risk factors, morbidity patterns, and outcomes were recorded. Patients were categorised into three groups based on Positive End Expiratory Pressure (PEEP): 5-8 cm of H2 O, 9-12 cm of H2 O, and &gt;12 cm of H2 O. Based on Peak Inspiratory Pressure (PIP), patients were divided into two groups: &lt;30 cm of H2 O and 30-35 cm of H2 O. Data were statistically analysed using the Chisquare test, Fisher’s test, and t-tests where applicable. Results: Out of a total of 120 children with moderate to severe ARDS, there were 75 males and 45 females. Direct lung injury accounted for 79 cases (65.5%), while indirect lung injury occurred in 41 cases (34.5%). Pneumonia and sepsis were the most common causes of direct and indirect lung injury, respectively. Among 75 cases of pneumonia, 40 deaths were reported (53.3%), and out of 37 cases of sepsis, 31 resulted in death (83%). On the day of admission, 38.3% of cases were classified as moderate ARDS and 61.7% as severe ARDS. The mortality rate for severe ARDS was 77%, compared to 43.5% for moderate ARDS. The mortality rate was 100% in the PEEP max &gt;12 cm of H2 O group and 84.4% in the PIP 30-35 cm of H2 O group. Conclusion: The majority of ARDS cases are due to direct lung injury caused by pneumonia, and the outcome is better than in cases of indirect lung injury. Mortality is nearly twice as high in severe ARDS as in moderate ARDS.

Comparative study of ventilation techniques with supraglottic airway devices in cats: volume-controlled vs pressure-controlled techniques.

This study compared the effectiveness of a new supraglottic airway device (SGAD) in cats undergoing anaesthesia using two types of mechanical ventilation: volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV). A total of 13 healthy cats (five male, eight female; median age 2 years [range 1-3]) were randomly allocated to either VCV or PCV. Five tidal volumes (6, 8, 10, 12 and 14 ml/kg) and five peak inspiratory pressures (4, 5, 6, 7 and 8 cmH2O) were randomly applied with a minute ventilation of 100 ml/kg/min. Various parameters, such as blood pressure, gas leakage, end-tidal CO2 (ETCO2) and work of breathing (WOB), were measured while using VCV or PCV. The occurrence of hypotension (mean arterial blood pressure <60 mmHg) was slightly less frequent with VCV (38 events, 65 ventilating sessions) than with PCV (40 events, 65 ventilating sessions), but this difference did not reach statistical significance (P = 0.429). The number of leakages did not differ between the VCV group (3 events, 65 ventilating sessions) and the PCV group (3 events, 65 ventilating sessions) (P = 1.000). Hypercapnia was identified when using VCV (10 events, 65 ventilating sessions) less frequently than when using PCV (17 events, 65 ventilating sessions), but this difference did not reach statistical significance (P = 0.194). The study found a significantly higher WOB in the PCV group compared with the VCV group (P <0.034). The present results suggested that both VCV and PCV can be used with an SGAD during anaesthesia, with VCV preferred for prolonged mechanical ventilation due to its lower workload. Adjusting tidal volume or inspiratory pressure corrects hypercapnia.

Comparison between Air-Q Self Pressurized Airway Device with Blocker and Proseal Laryngeal Mask Airway in anesthetized paralyzed adult female patients undergoing elective gynecological operations.

The Air-Q Self Pressurized Airway Device with Blocker (SP Blocker) was compared to the Proseal Laryngeal Mask Airway (PLMA) during positive pressure ventilation regarding the primary outcome (oropharyngeal leak pressure [OLP]), secondary outcomes (peak inspiratory pressure [PIP], inspired tidal volume [ITV], expired tidal volume [ETV], leak volume [LV] and leak fraction [LF]), insertion time, ventilation score, fiber-optic glottis view score, and postoperative laryngopharyngeal parameters (LPM). Adult healthy female patients scheduled for elective gynecological laparotomies under general anesthesia using controlled mechanical ventilation were recruited to a prospective randomized comparative clinical trial. Exclusion criteria were body mass index (BMI) ≥ 35 kg m -2 , El-Ganzouri score ≥ 5, upper airway problems, hiatus hernia or pregnancy. Patients were classified into an SP Blocker group ( n = 75) and a PLMA group ( n = 75). Primary and secondary outcomes were assessed initially and at fixed time points after successful insertion of devices. Initially after successful device insertion: the SP Blocker group showed statistically significant higher mean OLP (cmH 2 O) (29.46 ± 2.11 vs. 28.06 ± 1.83 respectively; 95% CI: -2.037 to -0.76, P < 0.0001), lower mean PIP (cmH 2 O) (15.49 ± 0.61 vs. 17.78 ± 1.04 respectively; 95% CI: 2.02 to 2.56, P < 0.0001), higher mean ITV (mL) (411 ± 30 vs. 403 ± 15 respectively; 95% CI: -15.65 to -0.347, P = 0.041), higher mean ETV (mL) (389 ± 12 vs. 354 ± 11 respectively; 95% CI: -38.72 to -31.29, P < 0.0001), lower mean LV (mL) (22 ± 18 vs. 49 ± 10 respectively; 95% CI: 22.3 to 31.7, P < 0.0001) and lower mean LF (%) (5 ± 2.04 vs. 12 ± 6.8 respectively; 95% CI: 5.38 to 8.62, P < 0.0001) than the PLMA group. Mean insertion time (seconds) was shorter in the SP Blocker group than the PLMA group (16.39 ± 2.81 vs. 18.63 ± 3.44 respectively; 95% CI: 1.23 to 3.25, P < 0.0001). The SP Blocker group offered a better fiber-optic glottis view score than the PLMA group without differences concerning ventilation score and LPM. SP Blocker provided as safe anesthesia during controlled mechanical ventilation as PLMA.

The effect of inverse ratio ventilation on cardiopulmonary function in obese laparoscopic surgery patients: A systematic review and meta-analysis.

This study aimed to evaluate the effect of inverse ratio ventilation (IRV) strategy on cardiopulmonary function in obese patients under general anesthesia. Databases such as China National Knowledge Infrastructure (CNKI), Wangfang, WeiP, Web of Science, the Cochrane Library, and PubMed were systematically searched. All randomized controlled trials' literature on IRV during laparoscopic surgery in obese patients under general anesthesia was collected. After data were extracted and cross-checked, Rev Man 5.3 software was used for meta-analysis. Finally, five randomized controlled clinical trials (RCTs) were included in the meta-analysis, with a total of 312 patients. Compared with the conventional ventilation group, the inspiratory peak pressure was lower at pneumoperitoneum 30 min and pneumoperitoneum 60 min; the PaO2 and oxygenation index were higher at pneumoperitoneum 60 min, and mean airway pressure was higher at pneumoperitoneum 30 min and pneumoperitoneum 60 min; the dynamic lung compliance was superior at pneumoperitoneum 30 min and pneumoperitoneum 60 min. IRV applied to laparoscopic surgery in obese patients under general anesthesia not only reduces peak airway pressure and improves intraoperative oxygenation index and PaO2 but also enhances mean airway pressure and dynamic lung compliance, which has a specific lung protective effect. It can be used as an option for the mechanical ventilation model in obese patients in clinical practice.

Clinical Efficacy of Ambu AuraGainTM and i-gel® in Patients Undergoing Elective Gynaecological Laparoscopic Surgeries Under General Anaesthesia: A Randomised Clinical Study

Introduction: Second-generation supraglottic airway devices that provide high seal pressures are found to be suitable for patients undergoing laparoscopic surgery, as they have a separate port for gastric tube insertion, effectively separating the airway and the oesophagus. The present study compares the usage of two such second-generation supraglottic devices-AuraGain™ and i-gel® in patients undergoing gynaecological laparoscopic surgeries. Aim: To compare the Oropharyngeal Leak Pressure (OLP) and airway pressures achieved by the i-gel® and Ambu AuraGain™ after insertion in the supine position and during laparoscopic carbon dioxide peritoneum in the Trendelenburg position. Materials and Methods: This randomised clinical, singleblinded study conducted at the Department of Anaesthesiology, Narayana Medical College, Nellore, Andhra pradesh, India involved 100 female patients undergoing elective gynaecological laparoscopic surgeries under general anaesthesia with controlled ventilation. The primary objective was to compare the clinical performance of Ambu AuraGain™ (Group-A) and i-gel® (Group-I) concerning their oropharyngeal seal pressures and airway pressures in gynaecological laparoscopic surgeries. The secondary outcomes measured included the time taken for insertion, ease of insertion of the device, effects on postinsertion haemodynamic parameters like heart rate, blood pressure, oxygen saturation, ease of gastric tube insertion, and fibreoptic bronchoscopic grading of the visualised glottic structures after device placement, as well as postoperative side effects like blood staining upon removal of the device and sore throat. Data were analysed using Student’s t-test and chi-square test. Results: The mean age in Group-A was 39.62±4.085 years, and in Group-I, it was 39.48±2.468 years. The mean peak inspiratory pressures after device insertion were 14.34 mmHg in Group-A and 16.66 mmHg in Group-I. Haemodynamic parameters postinsertion were similar in both groups {Group-A: Mean Heart Rate (HR) 87.22 bpm, Mean Arterial Pressure (MAP) 89.72 mmHg, Oxygen Saturation (SpO2 ) 99.58%; Group-I: Mean HR 87.50 bpm, MAP 89.72 mmHg, SpO2 99.72%). Fibreoptic bronchoscopic grading in Group-A was 0/0/9/41, and in Group-I, it was 0/0/11/39. Blood staining upon removal was noted in four patients (8%) in Group-A and in 3 patients (6%) in Group-I. Sore throat in the postoperative period was noted in 14% of patients in Group-A and 8% in Group-I. Conclusion: Ambu AuraGain™ was found to provide a better seal and higher OLP compared to the i-gel® in gynaecological laparoscopic surgeries and therefore provide safer and more effective ventilation for patients undergoing such surgeries. I-gel® was found to be easier and quicker to insert than the AuraGain™.

Lung tissue injury and hemodynamic effects of ventilations synchronized or unsynchronized to continuous chest compressions in a porcine cardiac arrest model

AimCompare lung injury and hemodynamic effects in synchronized ventilations (between two chest compressions) vs. unsynchronized ventilations during cardiopulmonary resuscitation (CPR) in a porcine model of cardiac arrest. MethodsTwenty pigs were randomized to either synchronized or unsynchronized group. Ventricular fibrillation was induced electrically and left for 1.5 minutes. Four minutes of basic chest compression:ventilation (30:2) CPR was followed by eight minutes of either synchronized or unsynchronized ventilations (10/min) during continuous compressions before defibrillation was attempted. Aortic, right atrial and intracerebral pressures, carotid and cerebral blood flow and cardiac output were measured. Airway monitoring included capnography and respiratory function monitor. Macro- and microscopic lung injuries were assessed post-mortem. ResultsThere were no significant differences between groups in any of the measured hemodynamic variables or inspiration time (0.4 vs. 1.0 s, p = 0.05). The synchronized ventilation group had lower median peak inspiratory airway pressure (57 vs. 94 cm H2O, p < 0.001), lower minute ventilation (3.7 vs. 9.4 l min−1, p < 0.001), lower pH (7.31 vs. 7.53, p < 0.001), higher pCO2 (5.2 vs. 2.5 kPa, p < 0.001) and lower pO2 (31.6 vs. 54.7 kPa, p < 0.001) compared to the unsynchronized group after 12 minutes of CPR. There was significant lung injury after CPR in both synchronized and unsynchronized groups. ConclusionSynchronized and unsynchronized ventilations resulted in similar hemodynamics and lung injury during continuous mechanical compressions of pigs in cardiac arrest. Animals that received unsynchronized ventilations with one second inspiration time at a rate of ten ventilations per minute were hyperventilated and hyperoxygenated.Institutional protocol number: FOTS, id 6948.

Pulmonary response prediction through personalized basis functions in a virtual patient model

Background and ObjectiveRecruitment maneuvers with subsequent positive-end-expiratory-pressure (PEEP) have proven effective in recruiting lung volume and preventing alveoli collapse. However, determining a safe, effective, and patient-specific PEEP is not standardized, and this more optimal PEEP level evolves with patient condition, requiring personalised monitoring and care approaches to maintain optimal ventilation settings. MethodsThis research examines 3 physiologically relevant basis function sets (exponential, parabolic, cumulative) to enable better prediction of elastance evolution for a virtual patient or digital twin model of MV lung mechanics, including novel elements to model and predict distension elastance. Prediction accuracy and robustness are validated against recruitment maneuver data from 18 volume-controlled ventilation (VCV) patients at 7 different baseline PEEP levels (0 to 12 cmH2O) and 14 pressure-controlled ventilation (PCV) patients at 4 different baseline PEEP levels (6 to 12 cmH2O), yielding 623 and 294 prediction cases, respectively. Predictions were made up to 12 cmH2O of added PEEP ahead, covering 6 × 2 cmH2O PEEP steps. ResultsThe 3 basis function sets yield median absolute peak inspiratory pressure (PIP) prediction error of 1.63 cmH2O for VCV patients, and median peak inspiratory volume (PIV) prediction error of 0.028 L for PCV patients. The exponential basis function set yields a better trade-off of overall performance across VCV and PCV prediction than parabolic and cumulative basis function sets from other studies. Comparing predicted and clinically measured distension prediction in VCV demonstrated consistent, robust high accuracy with R2 = 0.90–0.95. ConclusionsThe results demonstrate recruitment mechanics are best captured by an exponential basis function across different mechanical ventilation modes, matching physiological expectations, and accurately capture, for the first time, distension mechanics to within 5–10 % accuracy. Enabling the risk of lung injury to be predicted before changing ventilator settings. The overall outcomes significantly extend and more fully validate this digital twin or virtual mechanical ventilation patient model.

Factors Associated With Successful Extubation Readiness Testing in Children With Congenital Heart Disease.

In children with congenital heart disease, extubation readiness testing (ERT) is performed to evaluate the potential for liberation from mechanical ventilation. There is a paucity of data that suggests what mechanical ventilation parameters are associated with successful ERT. We hypothesized that ERT success would be associated with certain mechanical ventilator parameters. Data on daily ERT assessments were recorded as part of a quality improvement project. In accordance with our respiratory therapist-driven ventilator protocol, patients were assessed daily for ERT eligibility and tested daily, if eligible. Mechanical ventilation parameters were categorized a priori to evaluate the differences in levels of respiratory support. The primary outcome was ERT success. A total of 780 ERTs from 320 subjects (median [interquartile range] age 2.5 [0.6-6.5] months and median weight [interquartile range] 4.2 [3.3-6.9] kg) were evaluated. A total of 528 ERTs (68%) were passed, 306 successful ERTs (58%) resulted in extubation, and 30 subjects (9.4%) were re-intubated. There were statistically significant differences in the ERT pass rate for ventilator mode, peak inspiratory pressure, Δ pressure, PEEP, mean airway pressure ([Formula: see text]), and dead-space-to-tidal-volume ratio (all P < .001) but not for [Formula: see text]. ERT success decreased with increases in peak inspiratory pressure, Δ pressure, PEEP, [Formula: see text], and dead-space-to-tidal-volume ratio. Logistic regression revealed neonates, Δ pressure ≥ 11 cm H2O, and [Formula: see text] > 10 cm H2O were associated with a decreased odds of ERT success, whereas children ages 1-5 years and an [Formula: see text] of 0.31-0.40 had increased odds of ERT success. ERT pass rates decreased as ventilator support increased; however, some subjects were able to pass ERT despite high ventilator support. We found that [Formula: see text] was associated with ERT success and that protocols should consider using [Formula: see text] instead of PEEP thresholds for ERT eligibility. Cyanotic lesions were not associated with ERT success, which suggests that patients with cyanotic heart disease can be included in ERT protocols.

Perioperative Characteristics and Outcomes of Fontan Versus Non-Fontan Patients Undergoing Combined Heart-Liver Transplantation: A Retrospective Cohort Study

Combined heart-liver transplantation (CHLT) is becoming increasingly frequent as a maturing population of patients with Fontan-palliated congenital heart disease develop advanced liver fibrosis or cirrhosis. The authors present their experience with CHLT for congenital and noncongenital indications, and identify characteristics associated with poor outcomes that may guide intervention in high-risk patients. This was a single-center retrospective cohort study. This study was conducted at Vanderbilt University Medical Center in Nashville, Tennessee. The study included 16 consecutive adult recipients of CHLT at the authors' institution between April 2017 and February 2022. Eleven patients underwent transplantation for Fontan indications, and 5 were transplanted for non-Fontan indications. Compared with non-Fontan patients, Fontan recipients had longer cardiopulmonary bypass duration (199 v 119 minutes, p =m0.002), operative times (786 v 599 minutes, p = 0.01), and larger blood product transfusions (15.4 v 6.3 L, p = 0.18). Six of 16 patients required extracorporeal membrane oxygenation (ECMO), of whom 4 were Fontan patients who subsequently died. Patients who required ECMO had lower 5-hour lactate clearance (0.0 v 3.5 mmol/L, p = 0.001), higher number of vasoactive infusions, lower pulmonary artery pulsatility indices (0.58 v 1.77, p = 0.03), and higher peak inspiratory pressures (28.0 v 18.5 mmHg, p = 0.01) after liver reperfusion. Combined heart-liver transplantation in patients with Fontan-associated end-organ disease is particularly challenging and associated with higher recipient morbidity compared with non-Fontan-related CHLT. Early hemodynamic intervention for signs of ventricular dysfunction may improve outcomes in this growing high-risk population.

A COMPARATIVE STUDY TO ASSESS EFFECTS OF PNEUMOPERITONEUM AND TRENDELENBURG POSITION ON HEMODYNAMICS AND VENTILATORY MECHANICS DURING TOTAL LAPAROSCOPIC HYSTERECTOMY IN OBESE AND NON-OBESE PATIENTS

Background:Hysterectomy is a common gynaecological surgical procedure, with Laparoscopic hysterectomy (LH) emerging as a favorable approach due to its benefits such as shorter recovery periods and reduced complications. However, the creation of pneumoperitoneum and the Trendelenburg position required for total laparoscopic hysterectomy (TLH) can induce significant hemodynamic and ventilatory changes. Methodology: Our study included 60 patients who were categorized into two groups of 30 each based on their BMI: non-obese (BMI &lt; 30) and obese (BMI ≥ 30). All patients underwent routine pre-anaesthesia check-up followed by general anaesthesia. Diastolic blood pressure (DBP), systolic blood pressure (SBP), peripheral oxygen saturation (SpO2), heart rate (HR), mean arterial pressure (MAP), plateau pressure (PPLAT), peak pressure (PPEAK),and driving pressure (PDRIVING), end-tidal carbon dioxide (EtCO2) as well as static (CST) and dynamic (CDYN) lung compliance were measured at different time intervals including baseline, following induction of anaesthesia, insufflation, changing to Trendelenburg position, desufflation and after extubation. Results:The heart rate decreased on induction of anesthesia in both the groups and remained lower throughout the procedure but was statistically non-significant (p&gt;0.05). There was a rise in SBP, DBP, and MAP on insufflation and further with head-down positioning in both obese and non-obese patients, however, was statistically non-significant (p&gt;0.05). The PPEAK, PPLAT, and PDRIVING were increased on induction, following the creation of pneumoperitoneum as well as Trendelenburg position (p&lt;0.05). The values were higher in obese as compared to the non-obese. The static and dynamic compliance were lower at all time intervals in obese patients when compared to the non-obese group. Conclusion: Obese patients exhibit higher plateau pressure, peak inspiratory pressure, and driving pressure values, indicating increased airway resistance and potential ventilation challenges during surgery. Additionally, the reduced static and dynamic lung compliance values in obese patients suggest decreased lung elasticity and difficult ventilation.

Comparison of Efficacy of Pressure Controlled vs. Traditional Manual Mask Ventilation for Newborn Resuscitation - A Simulation-Based Pilot Randomized Control Trial.

To determine efficacy of non-invasive positive pressure face mask ventilation using a ventilator device (NIPPmV) for achieving early effective ventilation compared to that by self-inflating bag (SIB) or T- piece resuscitator (TPR). The authors video recorded 33 trained resuscitators using NIPPmV (provided using ventilator device), SIB [a 500ml silicone SIB without a positive end expiratory pressure (PEEP) valve] and a TPR. Using a continuous pressure recording system and a neonatal manikin, the authors evaluated the efficacy of the ventilation to achieve early effective ventilation during 30s of ventilation. The primary outcome was time to achieve effective chest rise. Secondary outcomes were peak inspiratory pressure (PIP), ventilation rate and the need to perform ventilation corrective steps during positive pressure ventilation (PPV) among the devices. Total 99 videos were recorded. The time(s) taken to achieve the first chest rise was significantly lesser in NIPPmV group compared to SIB and TPR (3.0 ± 1.7 vs. 3.7 ± 1.9 vs. 7.5 ± 5.4, respectively, p <0.001). The mean PIPdelivered by NIPPmV compared to SIB & TPR(19.8 ± 1.6 vs. 35.6 ± 7.4 vs. 17.8 ± 2.0cm H20 respectively; p <0.001) was more accurate with preset PIP. Ventilation, in terms of breath rate, was observed to be controlled more accurately with NIPPmV compared to SIB & TPR(50 vs. 42 vs. 33 per min respectively;p <0.001). The non-invasive positive pressure face mask ventilation using a ventilator (NIPPmV) resulted in achieving early, effective and consistent ventilation.

Pressure-controlled ventilation-volume guaranteed mode improves bronchial mucus transport velocity in patients during laparoscopic surgery for gynecological oncology: a randomized controlled study

BackgroundMechanical ventilation during general anesthesia may impair airway mucosal function. This study aimed to investigate the effect of pressure-controlled ventilation-volume guaranteed (PCV-VG) on bronchial mucus transport velocity (BTV) in patients during laparoscopic surgery for gynecological oncology compared with volume controlled ventilation (VCV).Methods66 patients undergoing elective a laparoscopic surgery for gynecological oncology. The patients were randomized into two group receiving either PCV-VG or VCV. a drop of methylene blue was placed on the surface of the airway mucosa under the bronchoscopeand, then the distance the dye movement was measured after 2, 4, and 6 min. Outcomes were assessed at T0 (5 min after endotracheal intubation and before initiation of pneumoperitoneum), T1 and T2 (1 and 2 h after stabilization of pneumoperitoneum respectively). BTV at T0, T1 and T2 was the primary outcome. Secondary outcomes included heart rate (HR), mean arterial pressure (MAP), body temperature, end-tidal CO2 pressure (PETCO2), tidal volume(VT), peak inspiratory pressure (PIP), mean inspiratory pressure (Pmean), respiratory rate (RR), and dynamic compliance (CDyn) at T0, T1, and T2.Results64 patients were included in the analysis. The median [interquartile range] BTV was significantly lower in VCV group at T1 and T2 that at T0 (P < 0.05). Furthermore, BTV was slightly reduced in PCV-VG compared with VCV. BTV in PCV-VG was significantly decreased at T2 compared with BTV at T0 (P < 0.05) and slightly decreased at T1 compared with T0(P > 0.05). Compared with the PCV-VG group, BTV in VCV group significantly decreased at T2 (P < 0.05). No participants experienced respiratory complications.ConclusionsPCV-VG is more suitable for patients undergoing laparoscopic surgery for gynecological oncology than VCV since it can protect mucociliary clearance function.Trial registrationThis trial is registered on https://www.chictr.org.cn/ in Chinese Clinical Trial Registry (ChiCTR.2200064564: Date of registration 11/10/2022).

Continuous chest compressions are associated with higher peak inspiratory pressures when compared to 30:2 in an experimental cardiac arrest model

BackgroundVentilation during cardiopulmonary resuscitation (CPR) has long been a part of the standard treatment during cardiac arrests. Ventilation is usually given either during continuous chest compressions (CCC) or during a short pause after every 30 chest compressions (30:2). There is limited knowledge of how ventilation is delivered if it effects the hemodynamics and if it plays a role in the occurrence of lung injuries. The aim of this study was to compare ventilation parameters, hemodynamics, blood gases and lung injuries during experimental CPR given with CCC and 30:2 in a porcine model.MethodsSixteen pigs weighing approximately 33 kg were randomized to either receive CPR with CCC or 30:2. Ventricular fibrillation was induced by passing an electrical current through the heart. CPR was started after 3 min and given for 20 min. Chest compressions were provided mechanically with a chest compression device and ventilations were delivered manually with a self-inflating bag and 12 l/min of oxygen. During the experiment, ventilation parameters and hemodynamics were sampled continuously, and arterial blood gases were taken every five minutes. After euthanasia and cessation of CPR, the lungs and heart were removed in block and visually examined followed by sampling of lung tissue which were examined using microscopy.ResultsIn the CCC group and the 30:2 group, peak inspiratory pressure (PIP) was 58.6 and 35.1 cmH2O (p < 0.001), minute volume (MV) 2189.6 and 1267.1 ml (p < 0.001), peak expired carbon dioxide (PECO2) 28.6 and 39.4 mmHg (p = 0.020), partial pressure of carbon dioxide (PaCO2) 50.2 and 61.1 mmHg (p = 0.013) and pH 7.3 and 7.2 (p = 0.029), respectively. Central venous pressure (CVP) decreased more over time in the 30:2 group (p = 0.023). All lungs were injured, but there were no differences between the groups.ConclusionsVentilation during CCC resulted in a higher PIP, MV and pH and lower PECO2 and PaCO2, showing that ventilation mode during CPR can affect ventilation parameters and blood gases.

Changes in respiratory mechanics in response to crystalloid infusions in extremely premature infants.

Extremely premature infants are at a higher risk of developing respiratory distress syndrome and circulatory impairments in the first few weeks of life. Administration of normal saline boluses to manage hypotension is a common practice in preterm infants. As a crystalloid, a substantial proportion might leak into the interstitium; most consequently the lungs in the preterm cohorts, putatively affecting ventilation. We downloaded and analyzed ventilator mechanics data in infants managed by conventional mechanical ventilation and administered normal saline bolus for clinical reasons. Data were downloaded for 30 min prebolus, 60 min during the bolus followed by 30 min postbolus. Sixteen infants (mean gestational age 25.2 ± 1 wk and birth weight 620 ± 60 g) were administered 10 mL/kg normal saline over 60 min. The most common clinical indication for saline was hypotension. No significant increase was noted in mean blood pressure after the saline bolus. A significant reduction in pulmonary compliance (mL/cmH2O/kg) was noted (0.43 ± 0.07 vs. 0.38 ± 0.07 vs. 0.33 ± 0.07, P = 0.003, ANOVA). This was accompanied by an elevation in the required peak inspiratory pressure to deliver set volume-guarantee (19 ± 2 vs. 22 ± 2 vs. 22 ± 3 mmHg, P < 0.0001, ANOVA), resulting in a higher respiratory severity score. Normal saline infusion therapy was associated with adverse pulmonary mechanics. Relevant pathophysiologic mechanisms might include translocation of fluid across pulmonary capillaries affected by low vascular tone and heightened permeability in extremes of prematurity, back-pressure effects from raised left atrial volume due to immature left-ventricular myocardium; complemented by the effect of cytokine release from positive pressure ventilation.NEW & NOTEWORTHY Administration of saline boluses is common in premature infants although hypovolemia is an uncommon underlying cause of hypotension. This crystalloid can redistribute into pulmonary interstitial space. In the presence of an immature myocardium and diastolic dysfunction, excess fluid can also be "edemagenic." This study on extremely premature infants (25 wk gestation) noted adverse influence on respiratory physiology after saline infusion. Clinicians need to choose judiciously and reconsider routine use of saline boluses in premature infants.