Positive End-expiratory Pressure Values Research Articles

Determination of optimal positive end-expiratory pressure using electrical impedance tomography in infants under general anesthesia: Comparison between supine and prone positions.

This study determined the optimal positive end-expiratory pressure levels in infants in supine and prone positions under general anesthesia using electrical impedance tomography (EIT). This prospective observational single-centre study included infants scheduled for surgery in the prone position. An electrical impedance tomography sensor was applied after inducing general anesthesia. The optimal positive end-expiratory pressure in the supine position was determined in a decremental trial based on EIT and compliance. Subsequently, the patient's position was changed to prone. Electrical impedance tomography parameters, including global inhomogeneity index, regional ventilation delay, opening pressure, the centre of ventilation, and pendelluft volume, were continuously obtained up to 1 h after prone positioning. The optimal positive end-expiratory pressure in the prone position was similarly determined. Data from 30 infants were analyzed. The mean value of electrical impedance tomography-based optimal positive end-expiratory pressure in the prone position was significantly higher than that in the supine position [10.9 (1.6) cmH2O and 6.1 (0.9) cmH2O, respectively (p < .001)]. Significant differences were observed between electrical impedance tomography- and compliance-based optimal positive end-expiratory pressure. Peak and mean airway, plateau, and driving pressures increased 1 h after prone positioning compared with those in the supine position. In addition, the centre of ventilation for balance in ventilation between the ventral and dorsal regions improved. The prone position required higher positive end-expiratory pressure than the supine position in mechanically ventilated infants under general anesthesia. EIT is a promising tool to find the optimal positive end-expiratory pressure, which needs to be individualized.

Adjustment of positive end-expiratory pressure to body mass index during mechanical ventilation in general anesthesia: BodyVent, a randomized controlled trial

BackgroundIn patients requiring general anesthesia, lung-protective ventilation can prevent postoperative pulmonary complications, which are associated with higher morbidity, mortality, and prolonged hospital stay. Application of positive end-expiratory pressure (PEEP) is one component of lung-protective ventilation. The correct strategy for setting adequate PEEP, however, remains controversial. PEEP settings that lead to a lower pressure difference between end-inspiratory plateau pressure and end-expiratory pressure (“driving pressure,” ΔP) may reduce the risk of postoperative pulmonary complications. Preliminary data suggests that the PEEP required to prevent both end-inspiratory overdistension and end-expiratory alveolar collapse, thereby reducing ΔP, correlates positively with the body mass index (BMI) of patients, with PEEP values corresponding to approximately 1/3 of patient’s respective BMI. Thus, we hypothesize that adjusting PEEP according to patient BMI reduces ΔP and may result in less postoperative pulmonary complications.MethodsPatients undergoing general anesthesia and endotracheal intubation with volume-controlled ventilation with a tidal volume of 7 ml per kg predicted body weight will be randomized and assigned to either an intervention group with PEEP adjusted according to BMI or a control group with a standardized PEEP of 5 mbar. Pre- and postoperatively, lung ultrasound will be performed to determine the lung aeration score, and hemodynamic and respiratory vital signs will be recorded for subsequent evaluation. The primary outcome is the difference in ΔP as a surrogate parameter for lung-protective ventilation. Secondary outcomes include change in lung aeration score, intraoperative occurrence of hemodynamic and respiratory events, oxygen requirements and postoperative pulmonary complications.DiscussionThe study results will show whether an intraoperative ventilation strategy with PEEP adjustment based on BMI has the potential of reducing the risk for postoperative pulmonary complications as an easy-to-implement intervention that does not require lengthy ventilator maneuvers nor additional equipment.Trial registrationGerman Clinical Trials Register (DRKS), DRKS00031336. Registered 21st February 2023.Trial statusThe study protocol was approved by the ethics committee of the Christian-Albrechts-Universität Kiel, Germany, on 1st February 2023. Recruitment began in March 2023 and is expected to end in September 2023.

Individualized positive end-expiratory pressure reduces driving pressure in obese patients during laparoscopic surgery under pneumoperitoneum: a randomized clinical trial.

During pneumoperitoneum (PNP), airway driving pressure (ΔPRS) increases due to the stiffness of the chest wall and cephalic shift of the diaphragm, which favors atelectasis. In addition, depending on the mechanical power (MP) formulas, they may lead to different interpretations. Patients >18 years of age with body mass index >35kg/m2 were included in a single-center randomized controlled trial during their admission for bariatric surgery by abdominal laparoscopy. Intra-abdominal pressure was set at 15mmHg at the pneumoperitoneum time point (PNP). After the recruitment maneuver, the lowest respiratory system elastance (ERS) was detected during the positive end-expiratory pressure (PEEP) step-wise decrement. Patients were randomized to the 1) CTRL group: ventilated with PEEP of 5cmH2O and 2) PEEPIND group: ventilated with PEEP value associated with ERS that is 5% higher than its lowest level. Respiratory system mechanics and mean arterial pressure (MAP) were assessed at the PNP, 5min after randomization (T1), and at the end of the ventilation protocol (T2); arterial blood gas was assessed at PNP and T2. ΔPRS was the primary outcome. Three MP formulas were used: MPA, which computes static PEEP × volume, elastic, and resistive components; MPB, which computes only the elastic component; and MPC, which computes static PEEP × volume, elastic, and resistive components without inspiratory holds. Twenty-eight patients were assessed for eligibility: eight were not included and 20 patients were randomized and allocated to CTRL and PEEPIND groups (n = 10/group). The PEEPIND ventilator strategy reduced ΔPRS when compared with the CTRL group (PEEPIND, 13 ± 2cmH2O; CTRL, 22 ± 4 cmH2O; p < 0.001). Oxygenation improved in the PEEPIND group when compared with the CTRL group (p = 0.029), whereas MAP was comparable between the PEEPIND and CTRL groups. At the end of surgery, MPA and MPB were correlated in both the CTRL (rho = 0.71, p = 0.019) and PEEPIND (rho = 0.84, p = 0.020) groups but showed different bias (CTRL, -1.9J/min; PEEPIND, +10.0J/min). At the end of the surgery, MPA and MPC were correlated in both the CTRL (rho = 0.71, p = 0.019) and PEEPIND (rho = 0.84, p = 0.020) groups but showed different bias (CTRL, -1.9J/min; PEEPIND, +10.0J/min). Individualized PEEP was associated with a reduction in ΔPRS and an improvement in oxygenation with comparable MAP. The MP, which solely computes the elastic component, better reflected the improvement in ΔPRS observed in the individualized PEEP group. The protocol was registered at the Brazilian Registry of Clinical Trials (U1111-1220-7296).

Helmet continuous positive airway pressure for patients’ transport using a single oxygen cylinder: A bench study

BackgroundContinuous positive airway pressure (CPAP) is frequently used to treat patients with acute respiratory failure in out-of-hospital settings. Compared to a facemask, the helmet has many advantages for the patient but requires a minimum gas flow of 60 L/min to avoid CO2 rebreathing. The aim of the present bench study was to evaluate the performance of four Venturi devices, connected to a single oxygen cylinder, in delivering helmet-CPAP with clinically relevant gas flow, fraction of inspired oxygen (FiO2), and positive end-expiratory pressure (PEEP) values. MethodsThree double-inlet Venturi systems (EasyVent, Ventuplus, Compact-HAR) were connected to full 5-L oxygen cylinders using a double flowmeter, and their oxygen requirements to reach different setups (flow 60-80 L/min; FiO2 0.4-0.5-0.6, PEEP 7.5-10-12.5 cmH2O) were tested. The fourth Venturi system (O2-MAX) was directly attached to the tank, and the flow and FiO2 delivered at preset FiO2 0.3 and 0.6 were recorded. The runtime of the cylinder was assessed. ResultsEasyVent, Ventuplus, and O2-MAX were able to deliver helmet-CPAP with clinically useful setups when connected to a single oxygen cylinder, while Compact-HAR did not. The runtime of the cylinders ranged between 28 and 60 minutes according to the preset flow and FiO2. The delivered gas flow decreased slowly and linearly with the drop in cylinder pressure until its exhaustion. ConclusionsHelmet-CPAP might be provided using portable Venturi systems connected to an oxygen cylinder, but not all of them are able to deliver it. The use of a double flowmeter allows delivery of both high flow and high FiO2 when double-inlet Venturi systems are used. Due to the flow drop observed during the cylinder consumption, a flow >60 L/min should be set when helmet-CPAP is started. Considering the flow drop phenomenon, the estimated duration of the tank runtime can be used with a margin of safety when planning patient transport.

Optimal positive end-expiratory pressure titration of intraoperative mechanical ventilation in different operative positions of female patients under general anesthesia

ObjectiveThis study aimed to compare the effectiveness and safety of different titrated methods used to determine individual positive end-expiratory pressure (PEEP) for intraoperative mechanical ventilation in female patients undergoing general anesthesia in different operative positions, and provide reference ranges of optimal PEEP values based on the titration. MethodsA total of 123 female patients who underwent elective open abdominal surgery under general anesthesia were included in this study. After endotracheal intubation, patients' body position was adjusted to the supine position, Trendelenburg positions at 10° and 20° respectively. PEEP was titrated from 20 cmH2O to 4 cmH2O, decreasing by 2 cmH2O every 1 min. Electrical impedance tomography (EIT), hemodynamic and respiratory mechanics parameters were continuously monitored and recorded. Optimal PEEP values and reference ranges were respectively calculated based on optimal EIT parameters, mean arterial pressure (MAP), and lung dynamic compliance (Cdyn). ResultsEIT-guided optimal PEEP was found to have higher values than those of the MAP-guided and Cdyn-guided methods for all three body positions (P < 0.001), and it was observed to more significantly inhibit hemodynamics (P < 0.05). The variable coefficients of EIT-guided optimal PEEP values were smaller than those of the other two methods, and this technique could provide better ventilation uniformity for dorsal/ventral lung fields and better balance for pulmonary atelectasis/collapse. The 95% reference ranges of EIT-guided optimal PEEP values were 4.6–13.8 cmH2O, 7.0–15.0 cmH2O and 8.6–17.0 cmH2O for the supine position, Trendelenburg 10°, and Trendelenburg 20° positions, respectively. ConclusionEIT-guided optimal PEEP titration was found to be a superior method for lung protective ventilation in different operative positions under general anesthesia. The calculated reference ranges of PEEP values based on the EIT-guided method can be used as a reference for intraoperative mechanical ventilation.

Comparison of the respiratory effects of commonly utilized general anaesthesia regimes in male Sprague-Dawley rats.

Background: Respiratory parameters in experimental animals are often characterised under general anaesthesia. However, anaesthesia regimes may alter the functional and mechanical properties of the respiratory system. While most anaesthesia regimes have been shown to affect the respiratory system, the effects of general anaesthesia protocols commonly used in animal models on lung function have not been systematically compared. Methods: The present study comprised 40 male Sprague-Dawley rats divided into five groups (N = 8 in each) according to anaesthesia regime applied: intravenous (iv) Na-pentobarbital, intraperitoneal (ip) ketamine-xylazine, iv propofol-fentanyl, inhaled sevoflurane, and ip urethane. All drugs were administered at commonly used doses. End-expiratory lung volume (EELV), airway resistance (Raw) and tissue mechanics were measured in addition to arterial blood gas parameters during mechanical ventilation while maintaining positive end-expiratory pressure (PEEP) values of 0, 3, and 6cm H2O. Respiratory mechanics were also measured during iv methacholine (MCh) challenges to assess bronchial responsiveness. Results: While PEEP influenced baseline respiratory mechanics, EELV and blood gas parameters (p < 0.001), no between-group differences were observed (p > 0.10). Conversely, significantly lower doses of MCh were required to achieve the same elevation in Raw under ketamine-xylazine anaesthesia compared to the other groups. Conclusion: In the most frequent rodent model of respiratory disorders, no differences in baseline respiratory mechanics or function were observed between commonly used anaesthesia regimes. Bronchial hyperresponsiveness in response to ketamine-xylazine anaesthesia should be considered when designing experiments using this regime. The findings of the present study indicate commonly used anaesthetic regimes allow fair comparison of respiratory mechanics in experimental animals undergoing any of the examined anaesthesia protocols.

Effect of modified high-flow oxygen therapy on positive end-expiratory pressure and end-expiratory lung volume based on simulated lung platform

ObjectiveThe aim of this study was to assess the effect of modified high-flow oxygen therapy on end-expiratory lung volume (EELV) and positive end-expiratory pressure (PEEP) in tracheotomized patients with normal pulmonary, acute hypoxic respiratory failure (AHRF) or chronic obstructive pulmonary disease (COPD). MethodsA ventilator and an artificial lung model were used to simulate the normal or strong inspiratory effort state of normal lung, AHRF and COPD patients. The traditional high-flow respiratory humidification therapy device connected with a standard interface (group A), and the modified therapy device added two types of resistance valves (group B, inner diameter 7.7 mm, length 24.0 mm; group C, inner diameter 7.7 mm, length 34.0 mm) to the exhalation end of the standard interface. The changes of end-expiratory lung volume (ΔEELV) and PEEP with the increase of flow rate (10 L/min, 20 L/min, 30 L/min, 40 L/min, 50 L/min, 60 L/min) in the three groups was recorded. ResultsUnder simulated conditions of normal lung, AHRF and COPD, as the flow rate increased by using the modified therapy device, the PEEP values in all groups showed an exponential increasing trend, and the ΔEELV also increased accordingly. In addition, under the same flow rate level, the PEEP values of the two modified high-flow oxygen therapies (Group B and Group C) were significantly higher than those of the standard high-flow oxygen therapy (Group A) (p < 0.05). In the normal lung model with normal or strong inspiratory effort, and in the AHRF or COPD model with strong inspiratory effort, when the flow rate was higher than 30 L/min, the PEEP levels of Group B were significantly lower than those of Group C (p < 0.05). In the AHRF model with normal inspiratory effort, when the flow rate was between 10 L/min and 60 L/min, the PEEP levels of Group B were significantly lower than those of Group C (p < 0.05). Moreover, in the COPD model with normal inspiratory effort, the PEEP levels of Group B were significantly lower than that of Group C only when the flow rate was 60 L/min (p < 0.05). ConclusionThe addition of different types of resistance valves to the high-flow exhalation end may be a feasible solution to improve the clinical efficacy of tracheotomized high-flow oxygen therapy.

Total dead space in children under general anesthesia.

Total dead space in children under general anesthesia.

Effect of individualized PEEP titration by ultrasonography on perioperative pulmonary protection and postoperative cognitive function in patients with chronic obstructive pulmonary disease

ObjectiveTo evaluate the effect of the individualized positive end-expiratory pressure (PEEP) lung protection ventilation strategy by combining driving pressure (ΔP) and pulmonary ultrasound (LUS)-based titration on lung function and postoperative cognitive function in patients with chronic obstructive pulmonary disease (COPD) during laparoscopic surgery.MethodsA total of 108 patients with COPD undergoing laparoscopic gastrointestinal surgery under general anesthesia were included in this study. They were randomly divided into three groups (n = 36): traditional volume ventilation group (Group C), fixed PEEP 5 cmH2O group (Group P), and ΔP combined with LUS-based PEEP titration in the resuscitation room group (Group T). All three groups were given volume ventilation mode, I:E = 1:2; In group C, VT was 10 mL/kg and PEEP was 0 cmH2O; In groups P and T, VT was 6 mL/kg and PEEP was 5 cmH2O; After mechanical ventilation for 15 min in Group T, ΔP in combination with LUS was used to titrate PEEP. The oxygenation index (PaO2/FiO2), airway platform pressure (Pplat), dynamic lung compliance (Cdyn), Montreal Cognitive Assessment (MoCA), and venous interleukin-6(IL-6) were recorded at the corresponding time points, and the final PEEP value in Group T was recorded.ResultsThe final PEEP value of Group T was (6.4 ± 1.2) cmH2O; Compared with groups C and P: PaO2/FiO2 and Cdyn in Group T were significantly increased (P < 0.05) and value of IL-6 was significantly decreased (P < 0.05) at the corresponding time points. Compared with group C, the MoCA score on day 7 after surgery in Group T was significantly higher (P < 0.05).ConclusionCompared with the traditional ventilation strategy, the individualized ΔP combined with LUS-based PEEP titration in patients with COPD during the perioperative period of laparoscopic surgery can play a better role in lung protection and can improve postoperative cognitive function.

Lung protection effect of EIT-based individualized protective ventilation strategy in patients with partial pulmonary resection.

This study aimed to evaluate the lung protection effect of an individualized protective ventilation strategy based on lung impedance tomography (EIT) technology in patients with partial pulmonary resection. Eighty patients of any gender, American Society of Anesthesiologists (ASA) classification I-II, age 30-64 years and body mass index (BMI) 18-28 kg/m2 who underwent elective thoracoscopic partial lung resection were selected and divided into 2 groups (n=40) using the random number table method: [positive end-expiratory pressure (PEEP) by electrical impedance tomography (EIT)] PEEPEIT group (experimental group) and control group. The PEEPEIT group used volume-controlled ventilation after one-lung ventilation, setting a tidal volume of 6 ml/kg and titrating the optimal PEEP value by EIT. Group C used volume-controlled ventilation after one-lung ventilation, setting a tidal volume of 6 ml/kg and a PEEP of 5 cm H2O. Clinical data were collected and recorded at 5 min after double lung ventilation (T0), single lung ventilation, 30 min after PEEP setting (T1), 60 min after PEEP setting (T2), the end of surgery, 10 min after resumption of double lung ventilation (T3) and 10 min after removal of the tracheal tube (T4), and serum surface active substance-associated protein-A (SP-A) concentrations were measured at T0, T3 and 1 d after surgery (T5). PEEP values were higher in the PEEPEIT group than in the control group at T1 and T2 (p-value <0.05); oxygenation index (OI) was higher in the PEEPEIT group compared to the control group at T2 and T3 (p-value <0.05); pulmonary dynamic compliance (Cdyn) was higher in the PEEPEIT group compared to the control group at T1 and T2 (p-value <0.05); intrapulmonary shunt rate (Qs/Qt) was lower in the PEEPEIT group compared to the control group at T1, T2 and at T3, the intrapulmonary shunt rate (Qs/Qt) was reduced in the PEEPEIT group compared to group C (p-value <0.05); at T5, the SP-A protein was reduced in the PEEPEIT group compared to group C. There was no statistically significant difference in the incidence of postoperative pulmonary complications between the two groups (p-value >0.05). The EIT-guided individualized protective ventilation strategy has a lung-protective effect in patients undergoing thoracoscopic partial lung resection.

Effect of different titration methods on right heart function and prognosis in patients with acute respiratory distress syndrome

BackgroundAcute respiratory distress syndrome (ARDS) is a common disease in intensive critical care(ICU), and the use of positive end-expiratory pressure(PEEP) during mechanical ventilation can increase the right heart afterload and eventually cause right heart dysfunction. For these factors causing acute cor pulmonale(ACP), especially inappropriate mechanical ventilation settings, it is important to explore the effect of PEEP on right heart function. ObjectiveTo investigate the effects of three titration methods on right heart function and prognosis in patients with ARDS. MethodsObservational, prospective study in which ARDS patients were enrolled into three distinct PEEP-titration strategies groups: guide, transpulmonary pressure-oriented and driving pressure-oriented. Prognostic indicators, right heart systolic and diastolic echocardiographic function indices, ventilatory parameters, blood gas analysis results, and respiratory mechanics Monitoring indices were collated and analyzed statistically by STATA 15 software. ResultsA total of 62 ARDS patients were enrolled into guide (G) group (n=40) for whom titrated PEEP values were 9±2cm H2O, driving pressure-oriented (DPO) group (n=12) with titrated PEEP values of 10±2cm H2O and transpulmonary pressure-oriented (TPO) group (n=10) with titrated PEEP values of 12±3cm H2O. Values were significantly higher for TPO than for G (p=0.616) or DPO (p=0.011). Compliance was significantly increased after 72 h in the TPO and DPO groups compared with the G group (p<0.001). Mean airway pressure at end-inspiratory obstruction (p=0.047), tricuspid annular plane systolic excursion (TAPSE, p<0.001) and right ventricular area change fraction (RVFAC, p=0.049) were all higher in the TPO and DPO groups than in the G group. E/A indices were significantly better in the TPO group than in the G or DPO groups (p=0.046). No significant differences in 28 day mortality were found among the three groups. Multivariate logistic regression analysis revealed that lung compliance and transpulmonary pressure-oriented PEEP titration method was negatively correlated to the increase in right ventricular systolic dysfunction. ConclusionTranspulmonary pressure-oriented PEEP titration improves oxygenation and pulmonary function and causes less right heart strain when compared to other PEEP-titration methods during mechanical ventilation of ARDS patients.

Dornase alfa in mechanically ventilated children with bronchiolitis: A retrospective cohort study.

The utility of the mucolytic dornase alfa in bronchiolitis has not been established, yet it is commonly used. The objective of this study was to compare outcomes of dornase alfa to standard of care treatments for bronchiolitis in mechanically ventilated pediatric patients. This was a retrospective, cohort study conducted at a single-center children's hospital evaluating pediatric patients with a diagnosis of bronchiolitis that required hospitalization and mechanical ventilation from January 1, 2010 to December 31, 2019. The primary outcome evaluated was length of time on mechanical ventilation. Secondary outcomes were pediatric intensive care unit (PICU) length of stay and length of hospitalization. Multiple linear regressions were used to assess the association of age, oxygen saturation index (OSI), positive end-expiratory pressure values, blood pH levels, respiratory syncytial virus status, and the use of other mucolytics, bronchodilator therapy, or chest physiotherapy treatment. Seventy-two patients were included in the study with 41 patients who were treated with dornase alfa. The patients who received dornase alfa had an average of 33.04 h longer on mechanical ventilation than those who did not (p = 0.0487). On average, they also had longer PICU and hospital stays by 2.05 days (p = 0.053) and 2.74 days (p = 0.02), respectively. In this study, pediatric patients who received dornase alfa had higher baseline OSI measurements than those who received standard of care, which impacted the primary outcome of time on mechanical ventilation and secondary outcome of time in the PICU. However, OSI, or any other variable, did not significantly affect results for the other secondary outcome of length of hospitalization. This study supports existing evidence that dornase alfa is not beneficial for bronchiolitis in pediatric patients, even in severe cases. Further prospective, randomized controlled trials are necessary to validate these outcomes.

Artificial lung ventilation in patients with morbid obesity during laparoscopic operations in the Trendelenburg position (literature review)

The literature review is devoted to the peculiarities of artificial lung ventilation (ALV) in patients with morbid obesity during laparoscopic oncosurgical interventions in the Trendelenburg position. At present, there are no consensus recommendations on the choice of the optimal ALV mode during anesthesia in this area of oncosurgery. When analyzing data obtained from other types of operations, there was no impression that there were significant advantages of any ALV modes, both with volume and pressure control. However, high values of positive end-expiratory pressure (PEEP) have the most evidence of benefit in this category of patients, and the inversion of the duration of the respiratory cycle phases without creating a high PEEP can help reduce the risk of lung damage when all other ALV techniques do not allow for adequate oxygenation.

One-Lung Ventilation and Postoperative Pulmonary Complications After Major Lung Resection Surgery. A Multicenter Randomized Controlled Trial

The effect of one-lung ventilation (OLV) strategy based on low tidal volume (TV), application of positive end-expiratory pressure (PEEP), and alveolar recruitment maneuvers (ARM) to reduce postoperative acute respiratory distress syndrome (ARDS) and pulmonary complications (PPCs) compared with higher TV without PEEP and ARM strategy in adult patients undergoing lobectomy or pneumonectomy has not been well established. Multicenter, randomized, single-blind, controlled trial. Sixteen Italian hospitals. A total of 880 patients undergoing elective major lung resection. Patients were randomized to receive lower tidal volume (LTV group: 4 mL/kg predicted body weight, PEEP of 5 cmH2O, and ARMs) or higher tidal volume (HTL group: 6 mL/kg predicted body weight, no PEEP, and no ARMs). After OLV, until extubation, both groups were ventilated using a tidal volume of 8 mL/kg and a PEEP value of 5 cmH2O. The primary outcome was the incidence of in-hospital ARDS. Secondary outcomes were the in-hospital rate of PPCs, major cardiovascular events, unplanned intensive care unit (ICU) admission, in-hospital mortality, ICU length of stay, and in-hospital length of stay. ARDS occurred in 3 of 438 patients (0.7%, 95% CI 0.1-2.0) and in 1 of 442 patients (0.2%, 95% CI 0-1.4) in the LTV and HTV group, respectively (Risk ratio: 3.03 95% CI 0.32-29, p=0.372). Pulmonary complications occurred in 125 of 438 patients (28.5%, 95% CI 24.5-32.9) and in 136 of 442 patients (30.8%, 95% CI 26.6-35.2) in the LTV and HTV group, respectively (risk ratio: 0.93, 95% CI 0.76-1.14, p=0.507). The incidence of major complications, in-hospital mortality, and unplanned ICU admission, ICU and in-hospital length of stay were comparable in both groups. In conclusion, among adult patients undergoing elective lung resection, an OLV with lower tidal volume, PEEP 5 cmH2O, and ARMs and a higher tidal volume strategy resulted in low ARDS incidence and comparable postoperative complications, in-hospital length of stay, and mortality.

Design of Fuzzy Logic-Based ARDS Berlin Definition for Ventilator Adjustments to Ensure Lung Protection

The studies done on lung protective strategies in medical ventilators have shown that tidal volume of 6-ml/ kg predicted body weight protects the lungs of a patient during the invasive ventilation for acute respiratory distress syndrome (ARDS) patients in intensive care unit. Corona virus disease 2019 has increased the need for mechanical ventilation, which are operated manually, in changing the settings on the mechanical ventilators. In this study, fuzzy logic method is used to develop a computer-aided decision-making to improve on the accuracy of the reasoning done during the ventilator setting adjustment, by adding the fuzzy reasoning concept into the ARDS Berlin definition. The ARDS positive end-expiratory pressure (PEEP) values were used in building the fuzzy rules of the fuzzy algorithm. From the experimental results, the algorithm mimics the recommended ARDS PEEP values with respect to the values of fraction of inspired oxygen (FiO2); the algorithm as well increases the respiratory rate and tidal volume for potential of Hydrogen (pH) less than 7.2; maintains the respiratory rate and tidal volume for pH between 7.2 and 7.4; decreases the respiratory rate; and maintains the tidal volume for pH greater than 7.4. The developed fuzzy system can therefore be applied as a physician–ventilator interface to guide the clinician/physician during the ventilation, so as, to reduce the human errors and ensure lung protection.

Pressure Sensor Stability Analysis of Positive End Expiratory Pressure Parameters in Flow Analyzer Design

The Positive End Expiratory Pressure (PEEP) parameter is a parameter that must be considered in the process of determining the patient's condition, a safe threshold, and must be in accordance with the settings. However, often the PEEP value on the ventilator does not match the settings so that the measuring instrument capable of detecting PEEP on the ventilator is the Flow Analyzer. The purpose of this study was to design a Flow Analyzer using the MPX2010 sensor to analyze the stability of the PEEP parameters on the ventilator. This study used PEEP settings of 0, 5, 8, 11, 14, 17, 20, 23, 26, and 29 cmH2O. Data were collected using a ventilator with VCV (Volume Control Ventilation) and PCV (Pressure Control Ventilation) modes. The tool used for reference from standard measurements uses the Standard Flow Analyzer tool. The results of this study indicate that the measurement accuracy of PEEP parameters with the Flow Analyzer module at each PEEP setting has the smallest error of ±0% at 0 cmH2O setting so that it also has the smallest value of 0 by standard. deviation and uncertainty (UA) value 0 at each setting. The Flow Analyzer measurement module has the largest error in the 5 cmH2O setting, which is ±13.2% with the largest correction value of 0.77. From the data obtained, it can be said that the monitoring of the PEEP parameter is quite stable even though the value is still out of tolerance. Monitoring of PEEP stability parameters can be implemented during the ventilator calibration process which needs to be carried out to analyze damage and reduce the time of damage to the ventilator.

Effect of Individualized PEEP on Perioperative Pulmonary Complications in Elderly Patients with Prostate Cancer Undergoing General Anesthesia in Trendelenburg Position: A Single-Center Retrospective Study.

This study aimed to explore the effect of individualized positive end-expiratory pressure (PEEP) on postoperative pulmonary complications (PPCs) in elderly patients with prostate cancer undergoing general anesthesia in Trendelenburg position (low-head and high-foot position at about 45° when patients were in supine position). The clinical data of 96 elderly patients undergoing Leonardo's robotic-assisted laparoscopic radical prostatectomy in Zhejiang Provincial People's Hospital from October 2021, to April 2023, were selected for retrospective analysis. Sixteen patients who had interrupted follow-up or did not meet the inclusion criteria were excluded, and 80 patients were finally included. The patients were divided into group A (lung-protective strategy using routine PEEP value, n = 40) and group B (lung-protective strategy using individualized PEEP value, n = 40) on the basis of different inversion methods. The PEEP value of group A was set as 5 cmH2O, whereas that of group B was determined under the guidance of static lung compliance. The incidences of PPCs on postoperative day 7 were statistically analyzed, and the serum levels of interleukin (IL) 6 (IL-6) and IL-8 in both groups were measured by enzyme-linked immunoadsordent assay (ELISA). The incidence of pulmonary complications was obviously lower in group B than in group A on postoperative day 7 (p < 0.001). Group B had lower levels of serum IL-6 and IL-8 at the end of surgery (T1) and 12 h after surgery (T2, p < 0.001); Higher oxygenation index values 10 min after successful titration of individualized PEEP (A3), 1 h after individualized PEEP ventilation (A4), 2 h after individualized PEEP ventilation (A5), 10 min after recovery of supine position (A6), and 30 min after tracheal extubation (A7); And lower hospitalization time (all p < 0.001) than group A. Individualized PEEP for elderly patients with prostate cancer undergoing general anesthesia in Trendelenburg position effectively relieves the release of inflammatory factors, reduces the occurrence of PPCs, and shortens hospitalization time. Thus, it is an effective protection strategy and has certain clinical value.

The calibration of esophageal pressure by proper esophageal balloon filling volume: A clinical study.

Esophageal pressure (Pes) can be used as a reliable surrogate for pleural pressure, especially in critically ill patients requiring personalized mechanical ventilation strategies. How to choose the proper esophageal balloon filling volume and then find the optimal value of esophageal pressure remains a challenge. The study aimed to assess the feasibility of catheters for Pes monitoring in mechanically ventilated patients. Twelve patients under pressure-controlled mechanical ventilation were included in this study. Raw esophageal pressure was recorded at different balloon filling volumes. Then, the P-V curves were determined. V WORK was the intermediate linear section on the end-expiratory P-V curve, and V BEST was the filling volume providing the maximum difference between Pes at end-inspiration and end-expiration. The raw value of Pes was recorded, and the calibrated values of Pes were calculated by calculating the esophageal wall pressure (Pew) and esophageal elastance (Ees). Twenty-four series of Pes measurements were performed. The mean V MIN and V MAX were 2.17 ± 0.49 ml (range, 1.0-3.0 ml) and 6.79 ± 0.83 ml (range, 5.0-9.0 ml), respectively, whereas V BEST was 4.69 ± 0.16 ml (range, 2.0-8.0 ml). Ees was 1.35 ± 0.51 cm H2O/ml (range, 0.26-2.38 cm H2O/ml). The estimated Pew at V BEST was 3.16 ± 2.19 cm H2O (range, 0-7.97 cm H2O). Patients with a body mass index (BMI) ≥ 25 kg/m2 had a significantly lower V MAX (5.88 [5.25-6] vs. 7.25 [7-8] ml, p = 0.006) and a significantly lower V BEST (3.69 [2.5-4.38] vs. 5.19 [4-6] ml, p = 0.036) than patients with a BMI < 25 kg/m2. Patients with positive end-expiratory pressure (PEEP) ≥ 10 cm H2O had a lower V MIN and V BEST than patients with PEEP < 10 cm H2O, P > 0.05. Patients in the supine position had a higher esophageal pressure than those in the prone position with the same balloon filling volume. Calibration of esophageal pressure to identify the best filling volume of esophageal balloon catheters is feasible. The esophageal pressure can be influenced by BMI, PEEP, and position. It is necessary to titrate the optimal inflation volume again when the PEEP values or the positions change.

Impact of positive end-expiratory pressure with alveolar recruitment maneuver on respiratory and oxygenation parameters of patients during laparoscopic bariatric surgery.

Laparoscopic bariatric surgery is frequently associated with disturbances in respiratory mechanics. An alveolar recruitment maneuver (ARM) with positive end-expiratory pressure (PEEP) is a strategy to overcome such respiratory conditions. This study aimed to evaluate the effect of ARM+PEEP on intraoperative and postoperative respiratory and hemodynamic parameters of patients with laparoscopic bariatric surgery. Patients who underwent laparoscopic bariatric surgery between 2009 and 2016 were retrospectively evaluated. The study sample was divided into four groups based on PEEP values and the presence of ARM: Group PEEP 5 (5 cm H2O PEEP only), Group PEEP 5/RM (5 cm H2O PEEP plus ARM), Group PEEP 10 (10 cm H2O PEEP only), Group PEEP 10/RM (10 cm H2O PEEP plus ARM). Patients' demographic characteristics, ventilatory, respiratory, and oxygenation parameters were recorded. Oxygenation index (PaO2/FiO2) was the study's primary outcome. There were 156, 158, 299, and 210 patients in Groups PEEP 5, PEEF 5/RM, PEEP 10, and PEEP 10/RM, respectively. Tidal volume, driving tidal volume/compliance, PaO2, PaO2/FiO2, and PaCO2 were significantly lower in Groups PEEP 5 and PEEP 5/RM, whereas SpO2 and FiO2 were significantly higher in Groups PEEP 5 and PEEP 5/RM (p<0.05). Patients in Group PEEP 5 had significantly higher end-tidal carbon dioxide (EtCO2) values than those of other groups (p<0.001). Patients in Group PEEP 5/RM had significantly higher SpO2 values than those in Group PEEP 5 (p<0.001). Rate of postoperative atelectasis was significantly higher in Group PEEP 5/RM compared to the other groups (p=0.011). A PEEP level of at least 10 cm H2O with ARM improved intraoperative respiratory parameters and caused a significant reduction in postoperative atelectasis.

Respiratory Mechanics and Gas Exchange in Acute Respiratory Distress Syndrome Associated with COVID-19

Aim. To compare respiratory mechanics and gas exchange in patients with acute respiratory distress syndrome (ARDS) with and without COVID-19.Material and methods. We examined 96 patients, who were divided into two groups. The main group included 48 patients with COVID-19-associated ARDS. The control group included 48 patients with ARDS not associated with COVID-19. Most characteristic patients were selected for the following baseline parameters: age, sex, SAPS II score, disease severity, plateau pressure (Pplateau), oxygenation index (PaO₂/FiO₂), and arterial-alveolar oxygen gradient (A-aO₂). Respiratory mechanics and gas exchange parameters assessed immediately after ARDS diagnosis and on days 1, 3 and 7 of treatment included arterial oxygen (PaO₂) and carbon dioxide (PaCO₂) pressure, tidal volume (Vt), respiratory rate (RR), respiratory minute volume (RMV), positive end expiratory pressure (PEEP), and Pplateau.Results. Patients in the main group had higher Vt (9.7 vs. 5.1 ml/kg, P&lt;0.001), RR (38 vs. 30 min-1, P&lt;0.001), and RMV (27.7 vs. 10.5 l/min, P&lt;0.001). Control group patients showed hypercapnia (PaCO₂ 43 vs. 38 mmHg, P&lt;0.001), lower respiratory compliance (30 vs. 48 ml/cm H₂O, P&lt;0.001) and ventilation ratio (VR) (1.5 vs. 2.0, P&lt;0.01). Lower PEEP values were required for patients in the main group. However, despite the higher rate of tracheal intubation in the control group (50% vs 16.7%) in the initial period of intensive care, the proportion of patients receiving invasive lung ventilation was significantly higher in the main group (33.3% vs.14.6%) by day 7.Conclusion. The initial phase (the first 7 days) of ARDS associated with COVID-19 is characterized by higher values of Vt, RR and RMV, as well as lung compliance vs «typical» ARDS with almost identical PaO₂/FiO₂ values.