The effect of driving pressure-guided versus conventional mechanical ventilation strategy on pulmonary complications following on-pump cardiac surgery: A randomized clinical trial

Intraoperative Factors Associated With Mechanical Ventilation Duration Following Aortic Surgery

OBJECTIVES

Prolonged postoperative mechanical ventilation is a common complication after major aortic surgery. The relationship between prolonged ventilation and intraoperative variables influenced by anesthesiologists, such as ventilation practices, fluid administration, and blood pressure control during major aortic surgery is unknown. We sought to identify perioperative factors, including intraoperative physiologic and anesthesia-related variables, which are associated with ventilation duration following aortic surgery.

DESIGN

Single-center retrospective observational study.

SETTING

A tertiary, high-volume cardiac surgery referral center.

PARTICIPANTS

Adult patients undergoing major aortic surgery requiring cardiopulmonary bypass (CPB).

INTERVENTIONS

None (retrospective observational study).

MEASUREMENTS AND MAIN RESULTS

The primary outcome was the duration of postoperative ventilation (hours). Mixed-effects regression was performed to identify factors associated with the primary outcome. Among the 647 patients included in this study, the median of postoperative mechanical ventilation duration was 9.0 (IQR 6.0, 14.4) hours, with 73 (11.3%) of patients receiving mechanical ventilation for more than 24 hours. Variables significantly associated with the outcome were increases in pre- to post-CPB driving pressure (β = 4.23; 95% CI [0.08, 8.39]; p = 0.04), reduction in pre- to post-CPB end-tidal carbon dioxide partial pressure (β = -5.12; 95% CI [-8.85, -1.39]; p < 0.001), and normalized transfusion volumes (β = 11.14; 95% CI [4.36, 17.91]; p < 0.001). Mechanical power was not associated with postoperative ventilation duration (β = -2.29; 95% CI [-6.48, 1.90]; p = 0.52).

CONCLUSIONS

Patients undergoing major aortic surgery are at risk for prolonged mechanical ventilation. Transfusion volume and pre- to post-CPB changes in driving pressures and end-tidal carbon dioxide are significantly associated with postoperative ventilation duration. Intraoperative mechanical ventilator power is not a significant predictor of mechanical ventilation duration after major aortic surgery. These variables are potentially modifiable by anesthesiologists and may be future therapeutic targets.

Effect of driving pressure-guided individualized positive end-expiratory pressure (PEEP) ventilation strategy on postoperative atelectasis in patients undergoing laparoscopic surgery as assessed by ultrasonography: study protocol for a prospective randomized controlled trial

BACKGROUND

Ventilator-induced lung injury caused by mechanical ventilation under general anesthesia as well as CO2 pneumoperitoneum and special positions for laparoscopy may increase the risk of postoperative pulmonary complications (PPCs). Lung protective ventilation under general anesthesia is advised by the guidelines to lower the risk of PPCs in surgical patients. However, there is considerable controversy about the optimal level of positive end-expiratory pressure (PEEP) and how to set it. Driving pressure reflects the overall respiratory stress and high driving pressure is an independent risk factor for PPCs. The purpose of this study is to explore whether driving pressure-guided individualized PEEP ventilation can lower the incidence of postoperative atelectasis by improving respiratory mechanics during laparoscopic surgery consequently lowering the incidence of PPCs compared with the traditional fixed PEEP ventilation strategy.

METHODS

The study will be a single-center, prospective, randomized controlled clinical study. A total of 106 adult patients with medium-to-high-risk PPCs undergoing laparoscopic surgery for more than 2 h will be randomly assigned in a 1:1 ratio to receive an individualized PEEP guided by minimum driving pressure (group D) or a fixed PEEP of 5 cmH2O (group C). Patients in group C will maintain a PEEP of 5 cmH2O throughout the whole process, and patients in group D will be administered individualized PEEP after the start of pneumoperitoneum to achieve minimum driving pressure until the end of the operation. The primary outcome is the LUS score at 24 h postoperatively. The secondary outcomes are the LUS scores at other time points, intraoperative respiratory mechanics and oxygenation index, incidence and specific types of PPCs at 7 days postoperatively.

DISCUSSION

This study will better evaluate the effect of individualized PEEP application guided by driving pressure on the incidence of postoperative atelectasis based on ultrasound assessment consequently the incidence of PPCs in patients undergoing prolonged laparoscopic surgery. The results may provide a clinical evidence for optimizing perioperative lung protection strategies.

TRIAL REGISTRATION

www.chictr.org.cn ChiCTR2300079041. Registered on December 25, 2023.

Mortality 30, 60, and 90 Days After Discharge Is Greater in Patients Who Experienced Postoperative Respiratory Depression and Pulmonary Complication

Upon the induction of general anesthesia, a predictable sequence of physiological changes occurs within the respiratory and neuromuscular systems. The sequelae of these changes include an assortment of postoperative pulmonary complications (PPCs), including postoperative respiratory depression (PORD), that are observed during the immediate postoperative period and in the post-anesthesia care unit (PACU). These adverse events are anticipated, because several of the drugs that are used during surgery (e.g., opioids, which are traditionally used to manage pain during and after surgery), albeit therapeutically beneficial, have these adverse effects as part of their pharmacology. Nevertheless, the effects are traditionally considered transitory. However, several studies provide evidence suggesting that PPC-related morbidity and mortality extend 30, 60, and even 90 days after discharge from the hospital. These studies are summarized and assessed in this narrative review. Although exact estimates vary depending on the definitions used, the type of surgery, patient population, and risk factors (such as age), it is clear that PORD and other PPCs can be severe postoperative complications with significant associated mortality risks that extend weeks to months after discharge from the hospital.

Classification of kinesiophobia in patients after cardiac surgery under extracorporeal circulation in China: latent profile and influencing factors analysis from a cross-sectional study

OBJECTIVE

To investigate the potential classification of kinesiophobia in patients after cardiac surgery under extracorporeal circulation from a psychosocial perspective, and analyse the characteristic differences among different latent levels of patients.

STUDY DESIGN

This is a cross-sectional study of Chinese adults after cardiac surgery under extracorporeal circulation, aged 18 years and older, recruited from a tertiary hospital in North China.

METHODS

This study uses latent profile analysis to identify potential classifications of kinesiophobia in questionnaires from 348 patients undergoing cardiac surgery under extracorporeal circulation. Multiple logistic regression analysis was used to evaluate the influencing factors at different latent classifications.

RESULTS

The average performance of each indicator in Model 3 is best suited for analysis, Entropy=0.873 and bootstrap likelihood ratio test (p)＜0.0001. The result of regression equation shows postoperative time (p<0.001), age, self-efficacy, pain and social support level (p<0.05) were the factors influencing the potential profile classification of patients after cardiac surgery under extracorporeal circulation.

CONCLUSION

The study identified three distinct classifications of patients: the low kinesiophobia group, the moderate kinesiophobia-high-risk perceived symptoms group and the high kinesiophobia-high exercise avoidance group (HK-HEAG). Addressing kinesiophobia, especially in older male patients during the early postoperative period, is crucial. Enhancing self-efficacy seems effective in reducing kinesiophobia, while increasing social support may not be as beneficial for the HK-HEAG. These findings provide a basis for implementing preventive interventions in cardiac rehabilitation.

TRIAL REGISTRATION NUMBER

The research is registered with the Chinese Clinical Trial Registry (ChiCTR2200057895).

Clinical practice of one-lung ventilation in mainland China: a nationwide questionnaire survey

BACKGROUND

Limited information is available regarding the application of lung-protective ventilation strategies during one-lung ventilation (OLV) across mainland China. A nationwide questionnaire survey was conducted to investigate this issue in current clinical practice.

METHODS

The survey covered various aspects, including respondent demographics, the establishment and maintenance of OLV, intraoperative monitoring standards, and complications associated with OLV.

RESULTS

Five hundred forty-three valid responses were collected from all provinces in mainland China. Volume control ventilation mode, 4 to 6 mL per kilogram of predictive body weight, pure oxygen inspiration, and a low-level positive end-expiratory pressure ≤ 5 cm H2O were the most popular ventilation parameters. The most common thresholds of intraoperative respiration monitoring were peripheral oxygen saturation (SpO2) of 90-94%, end-tidal CO2 of 45 to 55 mm Hg, and an airway pressure of 30 to 34 cm H2O. Recruitment maneuvers were traditionally performed by 94% of the respondents. Intraoperative hypoxemia and laryngeal injury were experienced by 75% and 51% of the respondents, respectively. The proportions of anesthesiologists who frequently experienced hypoxemia during OLV were 19%, 24%, and 7% for lung, cardiovascular, and esophageal surgeries, respectively. Up to 32% of respondents were reluctant to perform lung-protective ventilation strategies during OLV. Multiple regression analysis revealed that the volume-control ventilation mode and an SpO2 intervention threshold of < 85% were independent risk factors for hypoxemia during OLV in lung and cardiovascular surgeries. In esophageal surgery, working in a tier 2 hospital and using traditional ventilation strategies were independent risk factors for hypoxemia during OLV. Subgroup analysis revealed no significant difference in intraoperative hypoxemia during OLV between respondents who performed lung-protective ventilation strategies and those who did not.

CONCLUSIONS

Lung-protective ventilation strategies during OLV have been widely accepted in mainland China and are strongly recommended for esophageal surgery, particularly in tier 2 hospitals. Implementing volume control ventilation mode and early management of oxygen desaturation might prevent hypoxemia during OLV.

Lung protective ventilation guided by driving pressure improves pulmonary outcomes in heart transplantation

This study aimed to investigate whether driving pressure-guided ventilation can reduce postoperative pulmonary complications in patients who have undergone heart transplantation. Patients who underwent orthotopic heart transplantation were divided into two groups according to the perioperative ventilation strategy: (1) conventional lung-protective ventilation (group C) and (2) driving pressure-guided ventilation (group D). The primary outcome was the occurrence of postoperative pulmonary complications within 30 days of surgery. Univariate and multivariate logistic regression analyses were performed to evaluate the independent risk factors associated with postoperative pulmonary complications (PPCs). Compared with group C, patients in group D exhibited lower driving pressure. Oxygenation improved significantly in the early period after surgery in patients in group D. Group C exhibited a higher number of patients with postoperative pulmonary complications, especially respiratory infections and atelectasis. Patients in group D experienced a shorter duration of postoperative mechanical ventilation and a shorter stay in the intensive care unit. The conventional ventilation strategy, the high driving pressure level and the low PaO2 value at the end of the surgery were the independent risk factors for PPCs in heart transplantation. Compared with conventional lung-protective ventilation, driving pressure-guided ventilation was associated with improved pulmonary oxygenation and lower incidences of pulmonary complications among patients after heart transplantation.

Lung-protective ventilation and postoperative pulmonary complications during pulmonary resection in children: A prospective, single-centre, randomised controlled trial

BACKGROUND

Children are more susceptible to postoperative pulmonary complications (PPCs) due to their smaller functional residual capacity and higher closing volume; however, lung-protective ventilation (LPV) in children requiring one-lung ventilation (OLV) has been relatively underexplored.

OBJECTIVES

To evaluate the effects of LPV and driving pressure-guided ventilation on PPCs in children with OLV.

DESIGN

Randomised, controlled, double-blind study.

SETTING

Single-site tertiary hospital, 6 May 2022 to 31 August 2023.

PATIENTS

213 children aged < 6 years, planned for lung resection secondary to congenital cystic adenomatoid malformation.

INTERVENTIONS

Children were randomly assigned to LPV ( n  = 142) or control ( n  = 71) groups. Children in LPV group were randomly assigned to either driving pressure group ( n  = 70) receiving individualised positive end-expiratory pressure (PEEP) to deliver the lowest driving pressure or to conventional protective ventilation group ( n  = 72) with fixed PEEP of 5 cmH 2 O.

MAIN OUTCOME MEASURES

The primary outcome was the incidence of PPCs within 7 days after surgery. Secondary outcomes were pulmonary mechanics, oxygenation and mechanical power.

RESULTS

The incidence of PPCs did not differ between the LPV (24/142, 16.9%) and the control groups (15/71, 21.1%) ( P  = 0.45). The driving pressure was lower in the driving pressure group than in the 5 cmH 2 O PEEP group (15 vs. 17 cmH 2 O; P   =  0.001). Lung compliance and oxygenation were higher while the dynamic component of mechanical power was lower in the driving pressure group than in the 5 cmH 2 O PEEP group. The incidence of PPCs did not differ between the driving pressure (11/70, 15.7%) and the 5 cmH 2 O PEEP groups (13/72, 18.1%) ( P   =  0.71).

CONCLUSIONS

LPV did not decrease the occurrence of PPCs compared to non-protective ventilation. Although lung compliance and oxygenation were higher in the driving pressure group than in the 5 cmH 2 O PEEP group, these benefits did not translate into significant reductions in PPCs. However, the study is limited by a small sample size, which may affect the interpretation of the results. Future research with larger sample sizes is necessary to confirm these findings.

TRIAL REGISTRATION

ChiCTR2200059270.

Association between thoracic epidural anesthesia and driving pressure in adult patients undergoing elective major upper abdominal surgery: a randomized controlled trial

BACKGROUND

Thoracic epidural anesthesia (TEA) is associated with a knowledge gap regarding its mechanisms in lung protection and reduction of postoperative pulmonary complications (PPCs). Driving pressure (ΔP), an alternative indicator of alveolar strain, is closely linked to reduced PPCs with lower ΔP values. We aim to investigate whether TEA contributes to lung protection by lowering ΔP during mechanical ventilation.

METHODS

In this prospective, randomized, patient and evaluator-blinded parallel study, adult patients scheduled for elective major upper abdominal surgery were assigned to either the TEA group with combined thoracic epidural anesthesia and general anesthesia (TEA-GA) (n = 30) or the control group with only general anesthesia (GA) (n = 30).

MEASUREMENTS

The primary outcome was the minimum ΔP determined based on positive end-expiratory pressure (PEEP) after intubation. Secondary outcomes included the incidence of PPCs within seven days, the minimum ΔP at various time points, blood gas analysis, intensive care unit (ICU) admission rates, length of hospital stay, and 30-day mortality rate.

RESULTS

The TEA group had a significantly lower minimum ΔP titrated based on PEEP compared to the control group (11.23 ± 2.19 cmH2O vs. 12.67 ± 2.70 cmH2O; P = 0.028). Multivariate linear regression analysis showed that intraoperative TEA application (compared with its absence; unstandardized beta coefficient (B) = -1.289; P = 0.008) significantly correlated with ΔP. The incidence of PPCs did not differ significantly between the two groups (8 of 30 [26.7%] vs. 12 of 30 [40%]; P = 0.273), but the incidence of atelectasis in the TEA group was significantly lower than in the control group (5 of 30 [16.7%] vs. 12 of 30 [40.7%]; P = 0.012). Multivariate logistic regression analysis indicated that ΔP was the only variable significantly associated with PPCs (Adjusted Odds Ratio [OR] = 2.190; 95% Confidence Interval [CI]: 1.300 to 3.689; P = 0.003).

CONCLUSION

Compared to GA, TEA-GA can reduce intraoperative ΔP in patients undergoing major upper abdominal surgery, especially those undergoing laparoscopic surgery. However, compared to GA combined with ΔP-guided ventilation, TEA-GA combined with ΔP-guided ventilation does not reduce the risk of PPCs. There was no significant difference in the total use of various vasoactive drugs between the two groups.

TRIAL REGISTRATION

This study was registered in the Chinese Clinical Trial Registry (registration number ChiCTR2300068778 date of registration February 28, 2023).

Association between driving pressure-guided ventilation and postoperative pulmonary complications in surgical patients: a meta-analysis with trial sequential analysis

BACKGROUND

Prior studies have reported inconsistent results regarding the association between driving pressure-guided ventilation and postoperative pulmonary complications (PPCs). We aimed to investigate whether driving pressure-guided ventilation is associated with a lower risk of PPCs.

METHODS

We systematically searched electronic databases for RCTs comparing driving pressure-guided ventilation with conventional protective ventilation in adult surgical patients. The primary outcome was a composite of PPCs. Secondary outcomes were pneumonia, atelectasis, and acute respiratory distress syndrome (ARDS). Meta-analysis and subgroup analysis were conducted to calculate risk ratios (RRs) with 95% confidence intervals (CI). Trial sequential analysis (TSA) was used to assess the conclusiveness of evidence.

RESULTS

Thirteen RCTs with 3401 subjects were included. Driving pressure-guided ventilation was associated with a lower risk of PPCs (RR 0.70, 95% CI 0.56-0.87, P=0.001), as indicated by TSA. Subgroup analysis (P for interaction=0.04) found that the association was observed in non-cardiothoracic surgery (nine RCTs, 1038 subjects, RR 0.61, 95% CI 0.48-0.77, P< 0.0001), with TSA suggesting sufficient evidence and conclusive result; however, it did not reach significance in cardiothoracic surgery (four RCTs, 2363 subjects, RR 0.86, 95% CI 0.67-1.10, P=0.23), with TSA indicating insufficient evidence and inconclusive result. Similarly, a lower risk of pneumonia was found in non-cardiothoracic surgery but not in cardiothoracic surgery (P for interaction=0.046). No significant differences were found in atelectasis and ARDS between the two ventilation strategies.

CONCLUSIONS

Driving pressure-guided ventilation was associated with a lower risk of postoperative pulmonary complications in non-cardiothoracic surgery but not in cardiothoracic surgery.

SYSTEMATIC REVIEW PROTOCOL

INPLASY 202410068.

Maintaining moderate versus lower PEEP after cardiac surgery: a propensity-scored matched analysis

BACKGROUND

Setting positive end-expiratory pressure (PEEP) at around 5 cm H2O in the early postoperative period seems a common practice for most patients. It remains unclear if the routine application of higher levels of PEEP confers any meaningful clinical benefit for cardiac surgical patients. The aim of this study was to compare moderate versus conventional lower PEEP on patient-centered outcomes in the intensive care unit (ICU).

METHODS

This is a single-center retrospective study involving patients receiving cardiac surgery from June 2022 to May 2023. Propensity-score matching (PSM) was used to balance the baseline differences. Primary outcomes were the duration of mechanical ventilation and ICU length of stay. Secondary outcomes included PaO2/FiO2 ratio at 24 h and the need for prone positioning during ICU stay.

RESULTS

A total of 334 patients were included in the study, 102 (31%) of them received moderate PEEP (≥ 7 cm H2O) for the major time in the early postoperative period (12 h). After PSM, 79 pairs of patients were matched with balanced baseline data. The results showed that there was marginal difference in the distribution of mechanical ventilation duration (p = 0.05) and the Moderate PEEP group had a higher extubation rate at the day of T-piece trial (65 [82.3%] vs 52 [65.8%], p = 0.029). Applying moderate PEEP was also associated with better oxygenation. No differences were found regarding ICU length of stay and patients requiring prone positioning between groups.

CONCLUSION

In selective cardiac surgical patients, using moderate PEEP compared with conventional lower PEEP in the early postoperative period correlated to better oxygenation, which may have potential for earlier liberation of mechanical ventilation.