Intraoperative ventilatory strategies to prevent postoperative pulmonary complications: a meta-analysis

Effects of Neuraxial or General Anesthesia on the Incidence of Postoperative Pulmonary Complications in Patients Undergoing Peripheral Vascular Surgery: A Randomized Controlled Trial

OBJECTIVES

Postoperative complications after major surgery, especially in vascular procedures, are associated with a significant increase in costs and mortality. Postoperative pulmonary complications (PPCs) have a notable impact on morbidity and mortality. The primary aim of this present study was to evaluate the effects of spinal anesthesia compared with general anesthesia on the incidence of PPCs in patients undergoing lower extremity bypass surgery.

DESIGN

This study was designed as a prospective, randomized controlled clinical trial with 2 parallel arms.

SETTING

Two tertiary teaching hospitals.

PARTICIPANTS

We enrolled 128 adult patients with American Society of Anesthesiologists status II to IV who were scheduled to undergo elective lower extremity arterial bypass surgery.

INTERVENTIONS

Patients were assigned randomly to receive either general anesthesia or spinal anesthesia.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was the incidence of PPCs and secondary end points included hemodynamic and blood gas analysis perioperatively. A total of 128 patients were included in the study, with 123 patients completing the study protocol. Approximately 26.7% of patients who received general anesthesia experienced PPC, compared with 12.7% of those who received spinal anesthesia (p = 0.051). Patients who underwent spinal anesthesia had a lower incidence of hypotension and required fewer intraoperative vasoactive drugs (p < 0.001).

CONCLUSIONS

In this study, spinal anesthesia did not significantly reduce the incidence of PPCs in patients undergoing peripheral vascular surgery compared with general anesthesia. Neuraxial anesthesia may reduce the incidence of hypotension and the need for hemodynamic pharmacological support in patients undergoing peripheral arterial surgery, although further dedicated studies are required to validate these findings.

Effect of ultrasound-guided individualized positive end-expiratory pressure on the severity of postoperative atelectasis in elderly patients: a randomized controlled study

Postoperative pulmonary complications (PPCs) are common in patients undergoing general anesthesia, with atelectasis being a key contributor that increases postoperative mortality and prolongs hospitalization. Our research hypothesis is that ultrasound-guided individualized PEEP titration can reduce postoperative atelectasis. This single-center randomized controlled trial recruited elderly patients for laparoscopic surgery. Patients were randomly assigned to two group: the study group (individualized PEEP groups, PEEP Ind group) and the control group (Fixed PEEP group, PEEP 5 group). All patients in these two groups received volume-controlled ventilation during general anesthesia. Patients in the study group were given ultrasound-guided PEEP, while those in the control group were given a fixed 5 cmH2O PEEP. Bedside ultrasound assessed lung ventilation. The primary outcome was the severity of atelectasis within seven days post-surgery. Eighty-nine patients scheduled for elective laparoscopic radical surgery for colorectal cancer were enrolled in our study. Lung ultrasound scores (LUSs) in the study group during postoperative seven days was significantly decreased compared with that in the control group (P < 0.05). The severity of postoperative atelectasis in the study group was significantly improved. The incidence of PPCs during postoperative 7 days in the study group was significantly less than that in the control group (48.6% vs. 77.8%; RR = 0.625; CI = 0.430-0.909; P = 0.01). In elderly patients undergoing laparoscopic radical resection, lung ultrasound-guided individualized PEEP can alleviate the severity of postoperative atelectasis.Clinical trial number and registry URL: No. ChiCTR2200062979 ( https://www.chictr.org.cn ).

Positive end-expiratory pressure and the incidence of postoperative pulmonary complications in patients undergoing general anaesthesia

AIM OF THE STUDY

To evaluate the effect of intraoperative positive end-expiratory pressure and driving pressure on the development of postoperative pulmonary complications.

METHOD

The prospective study included 83 patients undergoing abdominal surgery and receiving general anaesthesia. Patients were divided into two groups: with low intraoperative positive end-expiratory pressure (0-2cm H2O) and with high intraoperative positive end-expiratory pressure (8-10cm H2O). The primary endpoint is the development of postoperative pulmonary complications during follow-up.

RESULTS

The incidence of postoperative pulmonary complications in the group of low intraoperative positive end-expiratory pressure was 9.8%, while in the group of high positive end-expiratory pressure was 7.1% (p = 0.6), demonstrating that high positive end-expiratory pressure used during general anaesthesia does not affect the frequency of complications (odds ratio = 0.71, p = 0.6). In the multivariate analysis that controls for all confounders, driving pressure resulted in a significant and independent risk factor for complications.

CONCLUSION

High intraoperative positive end-expiratory pressure does not affect the frequency of postoperative pulmonary complications. The increase in driving pressure is a risk factor for complications. Positive end-expiratory pressure is easily implemented, and its use does not result in significant economic costs.

Airway Management for Acute and Reconstructive Burns: Our 30-year Experience

Airway management in both acute and reconstructive burn patients can be a major challenge for evaluation, intubation, and securing the airway in the setting of altered airway structure. Airway evaluation in both acute and reconstructive patients includes examination for evidence of laryngeal and supraglottic edema and structural changes due to trauma and/or scarring that will impact the successful approach to acquiring an airway for surgical procedures and medical recovery. The approach to acquiring a successful airway is rarely standard laryngoscopy and often requires fiberoptic bronchoscopy and a variety of airway manipulation techniques. Tracheostomy should be reserved for those with classic requirements of ventilatory and/or mechanical failure or severe upper airway burns. Even securing an airway for surgical procedures, especially with patients suffering injuries involving the head and neck, can be nonstandard and requires creative and flexible approaches to be successful. After much trial and error over the past 30 years in a large burn center, our multidisciplinary team has learned many valuable lessons. This review will focus on our current approach to safe airway management in acute and reconstructive burn patients.

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

BACKGROUND

Inadequate 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.

METHODS

Two-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.

RESULTS

Out 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].

CONCLUSIONS

High 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.

The effect of intraoperative positive end expiratory pressure and tidal volume on postoperative acute kidney injury after orthopedic surgery

BACKGROUND

To test whether higher intraoperative PEEP levels and/or higher TV levels are associated with higher incidence of postoperative AKI within the first postoperative week, in adult patients having orthopedic surgeries under general anesthesia.

METHODS

We conducted a sub analysis of a non-randomized alternating intervention cross over study performed in patients undergoing orthopedic surgery under general anesthesia at Cleveland Clinic, Cleveland, OH. We included four different combinations of PEEP (5 or 8 cm H2 O) and TV (6 or 10 mL/kg of PBW) that alternated each week in the six orthopedic operating rooms. Our primary outcome was postoperative AKI defined by the KDIGO criteria with baseline creatinine as the closest preoperative value to the time of surgery obtained within 30 days and postoperative value as the highest creatinine value within 7 days after surgery. Secondary outcome was the maximum postoperative in-hospital creatinine level within seven postoperative days.

MAIN RESULTS

A total of 1933 patients were included in the analysis. The incidence of AKI was 6.8% in the study population and similar in high TV versus low TV group and high PEEP versus low PEEP group. Neither TV nor PEEP significantly impacted AKI incidence. The estimated odds ratio of AKI comparing TV = 6 mL/kg to TV = 10 mL/kg was 0.96 (97.5% CI: 0.63, 1.46; p = .811); while the estimated odds ratio of AKI comparing PEEP = 5cm H2 O to PEEP = 8cm H2 O was 0.92 (97.5% CI: 0.60, 1.39; p = .623). No interaction was found between TV and PEEP on AKI. Additionally, neither TV nor PEEP had a significant effect on the seven postoperative day creatinine levels.

CONCLUSION

Higher levels of PEEP or TV during mechanical ventilation in adult patients undergoing orthopedic surgeries under general anesthesia do not increase the odds of developing postoperative AKI within the narrow limits studied.

Positive end-expiratory pressure and postoperative complications in patients with obesity: a review and meta-analysis

OBJECTIVE

In patients with obesity, use of positive end-expiratory pressure (PEEP) > 5 cm H₂ O (centimeters of water) has been shown to prevent intraoperative atelectasis. This study compares the rate of postoperative pulmonary complications (PPCs) associated with PEEP > 5 cm H₂ O and PEEP ≤ 5 cm H₂ O in patients with obesity who underwent surgery under general anesthesia with mechanical ventilation.

METHODS

This study searched Medline, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL), and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) using the terms "PEEP," "anesthesia," and "ventilation." Cochrane ReviewManager (RevMan) version 5 was used for data analysis. The primary outcome was a composite of PPCs, including atelectasis, pneumonia, pneumothorax, and acute respiratory failure.

RESULTS

The initial search identified 903 titles and abstracts, and 4 randomized controlled trials were included for analysis. We included a total of 2116 participants from four randomized controlled trials that compared PEEP ≤ 5 cm H₂ O with PEEP > 5 cm H₂ O in adult patients with obesity. There was no statistically significant difference in PPCs between the PEEP ≤ 5 cm H₂ O and PEEP > 5 cm H₂ O groups (risk ratio = 2.21, 95% CI: 0.41-11.83; p = 0.35). However, a significant heterogeneity was found within included studies (I²  = 53%).

CONCLUSIONS

It is unclear whether PEEP > 5 cm H₂ O improves the postoperative clinical outcome in patients with obesity, which is in contrast to previously established evidence that it reduces atelectasis in patients with obesity.

Postoperative Respiratory Failure and Advanced Ventilator Settings

Postoperative respiratory failure has a multifactorial etiology, of which atelectasis is the most common mechanism. Its injurious effects are magnified by surgical inflammation, high driving pressures, and postoperative pain. Chest physiotherapy and noninvasive ventilation are good options to prevent progression of respiratory failure. Acute respiratory disease syndrome is a late and severe finding, which is associated with high morbidity and mortality. If present, proning is a safe, effective, and underutilized therapy. Extracorporeal membrane oxygenation is an option only when traditional supportive measures have failed.

The impact of ultrasound-guided recruitment maneuvers on the risk of postoperative pulmonary complications in patients undergoing general anesthesia

Introduction

Postoperative pulmonary complications are among the most frequent problems in perioperative care. The risk of their development depends not only on the parameters associated with the patient’s initial clinical condition, but also on the employed anesthesia technique, the method of mechanical ventilation, and the type and technique of the surgical procedure. Atelectasis is the most common complication, affecting nearly 90% of the patients undergoing general anesthesia.

Aim

The aim of this study was to determine whether it was possible to positively impact the postoperative period and reduce the frequency of postoperative pulmonary complications via patient-based intraoperative ultrasound-guided recruitment maneuvers.

Methodology

The course of the postoperative period was analyzed in two groups of patients. One of them comprised 100 patients in whom no recruitment maneuvers were performed during general anesthesia. The other group (100 patients) consisted of patients in whom patient-based ultrasound-guided pulmonary recruitment maneuvers were performed.

Results

In the recruitment group, the postoperative hospitalization was statistically significantly shorter (p = 0.003) and the risk of intensive care treatment significantly lower. Additionally, the need for prolonged postoperative mechanical ventilation was reduced, as was the risk of respiratory tract infections.

Conclusions

Intraoperative ultrasound-guided recruitment maneuvers reduce the frequency of postoperative pulmonary complications.

Intra-operative ventilator mechanical power as a predictor of postoperative pulmonary complications in surgical patients: A secondary analysis of a randomised clinical trial

BACKGROUND

Studies in critically ill patients suggest a relationship between mechanical power (an index of the energy delivered by the ventilator, which includes driving pressure, respiratory rate, tidal volume and inspiratory pressure) and complications.

OBJECTIVE

We aimed to assess the association between intra-operative mechanical power and postoperative pulmonary complications (PPCs).

DESIGN

Post hoc analysis of a large randomised clinical trial.

SETTING

University-affiliated academic tertiary hospital in Melbourne, Australia, from February 2015 to February 2019.

PATIENTS

Adult patients undergoing major noncardiothoracic, nonintracranial surgery.

INTERVENTION

Dynamic mechanical power was calculated using the power equation adjusted by the respiratory system compliance (CRS). Multivariable models were used to assess the independent association between mechanical power and outcomes.

MAIN OUTCOME MEASURES

The primary outcome was the incidence of PPCs within the first seven postoperative days. The secondary outcome was the incidence of acute respiratory failure.

RESULTS

We studied 1156 patients (median age [IQR]: 64 [55 to 72] years, 59.5% men). Median mechanical power adjusted by CRS was 0.32 [0.22 to 0.51] (J min-1)/(ml cmH2O-1). A higher mechanical power was also independently associated with increased risk of PPCs [odds ratio (OR 1.34, 95% CI, 1.17 to 1.52); P < 0.001) and acute respiratory failure (OR 1.40, 95% CI, 1.21 to 1.61; P < 0.001).

CONCLUSION

In patients receiving ventilation during major noncardiothoracic, nonintracranial surgery, exposure to a higher mechanical power was independently associated with an increased risk of PPCs and acute respiratory failure.

TRIAL REGISTRATION

Australia and New Zealand Clinical Trials Registry no: 12614000790640.

A nomogram to predict postoperative pulmonary complications after cardiothoracic surgery

OBJECTIVE

The objective was to develop a novel scoring system that would be predictive of postoperative pulmonary complications in critically ill patients after cardiac and major vascular surgery.

METHODS

A total of 17,433 postoperative patients after coronary artery bypass graft, valve, or thoracic aorta repair surgery admitted to the cardiovascular intensive care units at Cleveland Clinic Main Campus from 2009 to 2015. The primary outcome was the composite of postoperative pulmonary complications, including pneumonia, prolonged postoperative mechanical ventilation (>48 hours), or reintubation occurring during the hospital stay. Elastic net logistic regression was used on the training subset to build a prediction model that included perioperative predictors. Five-fold cross-validation was used to select an appropriate subset of the predictors. The predictive efficacy was assessed with calibration and discrimination statistics. Post hoc, of 13,353 adult patients, we tested the clinical usefulness of our risk prediction model on 12,956 patients who underwent surgery from 2015 to 2019.

RESULTS

Postoperative pulmonary complications were observed in 1669 patients (9.6%). A prediction model that included baseline and demographic risk factors along with perioperative predictors had a C-statistic of 0.87 (95% confidence interval, 0.86-0.88), with a corrected Brier score of 0.06. Our prediction model maintains satisfactory discrimination (C-statistics of 0.87) and calibration (Brier score of 0.07) abilities when evaluated on an independent dataset of 12,843 recent adult patients who underwent cardiovascular surgery.

CONCLUSIONS

A novel prediction nomogram accurately predicted postoperative pulmonary complications after major cardiac and vascular surgery. Intensivists may use these predictors to allow for proactive and preventative interventions in this patient population.

Anesthesia considerations to reduce motion and atelectasis during advanced guided bronchoscopy

Partnership between anesthesia providers and proceduralists is essential to ensure patient safety and optimize outcomes. A renewed importance of this axiom has emerged in advanced bronchoscopy and interventional pulmonology. While anesthesia-induced atelectasis is common, it is not typically clinically significant. Advanced guided bronchoscopic biopsy is an exception in which anesthesia protocols substantially impact outcomes. Procedure success depends on careful ventilation to avoid excessive motion, reduce distortion causing computed tomography (CT)-to-body-divergence, stabilize dependent areas, and optimize breath-hold maneuvers to prevent atelectasis. Herein are anesthesia recommendations during guided bronchoscopy. An FiO₂ of 0.6 to 0.8 is recommended for pre-oxygenation, maintained at the lowest tolerable level for the entire the procedure. Expeditious intubation (not rapid-sequence) with a larger endotracheal tube and non-depolarizing muscle relaxants are preferred. Positive end-expiratory pressure (PEEP) of up to 10-12 cm H₂O and increased tidal volumes help to maintain optimal lung inflation, if tolerated by the patient as determined during recruitment. A breath-hold is required to reduce motion artifact during intraprocedural imaging (e.g., cone-beam CT, digital tomosynthesis), timed at the end of a normal tidal breath (peak inspiration) and held until pressures equilibrate and the imaging cycle is complete. Use of the adjustable pressure-limiting valve is critical to maintain the desired PEEP and reduce movement during breath-hold maneuvers. These measures will reduce atelectasis and CT-to-body divergence, minimize motion artifact, and provide clearer, more accurate images during guided bronchoscopy. Following these recommendations will facilitate a successful lung biopsy, potentially accelerating the time to treatment by avoiding additional biopsies. Application of these methods should be at the discretion of the anesthesiologist and the proceduralist; best medical judgement should be used in all cases to ensure the safety of the patient.

Individualized positive end-expiratory pressure (PEEP) during one-lung ventilation for prevention of postoperative pulmonary complications in patients undergoing thoracic surgery: A meta-analysis

BACKGROUND

Positive end-expiratory pressure (PEEP) is an important part of the lung protection strategies for one-lung ventilation (OLV). However, a fixed PEEP value is not suitable for all patients. Our objective was to determine the prevention of individualized PEEP on postoperative complications in patients undergoing one-lung ventilation.

METHOD

We searched the PubMed, Embase, and Cochrane and performed a meta-analysis to compare the effect of individual PEEP vs fixed PEEP during single lung ventilation on postoperative pulmonary complications. Our primary outcome was the occurrence of postoperative pulmonary complications during follow-up. Secondary outcomes included the partial pressure of arterial oxygen and oxygenation index during one-lung ventilation.

RESULT

Eight studies examining 849 patients were included in this review. The rate of postoperative pulmonary complications was reduced in the individualized PEEP group with a risk ratio of 0.52 (95% CI:0.37-0.73; P = .0001). The partial pressure of arterial oxygen during the OLV in the individualized PEEP group was higher with a mean difference 34.20 mm Hg (95% CI: 8.92-59.48; P = .0004). Similarly, the individualized PEEP group had a higher oxygenation index, MD: 49.07mmHg, (95% CI: 27.21-70.92; P < .0001).

CONCLUSIONS

Individualized PEEP setting during one-lung ventilation in patients undergoing thoracic surgery was associated with fewer postoperative pulmonary complications and better perioperative oxygenation.

Effect of mechanical ventilation during cardiopulmonary bypass on oxidative stress: a randomized clinical trial

BACKGROUND

Cardiopulmonary bypass (CPB) causes systemic oxidative stress response and endothelial damage in systemic organs. We investigated the effects of positive end-expiratory pressure (PEEP) and mechanical ventilation (MV) applications on oxidative stress in CPB.

METHODS

Seventy-one patients were recruited and 60 completed the study. Randomized groups: MV off (Group 1); MV on, tidal volume (TV) at 3-4 mL.kg^-1 (Group 2); MV on, TV at 3-4 mL.kg^-1, PEEP at 5 cmH2O (Group 3), n = 20 in each group. As oxidative stress markers, we used glutathione peroxidase (GPx), total antioxidant status (TAS), total oxidant status (TOS), total and native thiol (TT, NT), malondialdehyde (MDA), and catalase. We also investigated the correlation between oxidative stress and postoperative intubation time.

RESULTS

The postoperative GPx levels in Group 2 were higher than Group 3 (p = 0.017). In groups 2 and 3, TAS levels were higher postoperatively than intraoperatively (p = 0.001, p = 0.019, respectively). In Group 2, the TT levels were higher postoperatively than preoperatively and intraoperatively (p = 0.008). In Group 3, the postoperative MDA levels were higher than preoperatively (p = 0.001) and were higher than both postoperative levels of Group 1 and 2 (p = 0.043, p = 0.003). As the preoperative TAS (Group 2) decreased and the postoperative NT (Group 2) and catalase (Group 3) increased, the postoperative intubation time lengthened.

CONCLUSION

MV ( 3-4 mL.kg^-1) alone seems to be the most advantageous strategy. Prolonged postoperative intubation time was associated with both increased NT and catalase levels.

[Intraoperative Ventilation Approaches to One-lung Ventilation]

The management of thoracic surgery patients is challenging to the anesthetist, since one-lung ventilation (OLV) includes at least two major conditions: sufficient oxygenation and lung protection. The first is mainly because the ventilation of one lung is stopped while perfusion to that lung continues; the latter is related to the fact that the whole ventilation is applied to only a single lung. Recommendations for maintaining the oxygenation and methods of lung protection may contradict each other (e. g. high vs. low inspiratory oxygen fraction (FiO₂), high vs. low tidal volume, etc.). Therefore, a high degree of pathophysiological understanding and manual skills are required in the management of these patients.In light of recent clinical studies, this review focuses on a current protective strategy for OLV, which includes a possible decrease in FiO₂, lowered V_T, the application of positive end-expiratory pressure (PEEP) to the dependent and continuous positive airway pressure (CPAP) to the non-dependent lung and alveolar recruitment manoeuvres as well. Other approaches such as the choice of anaesthetics, remote ischemic preconditioning, fluid management and pain therapy can support the success of ventilatory strategy. The present work describes new developments that may change the classical approach in this respect.

Lung Ultrasonography in the Monitoring of Intraoperative Recruitment Maneuvers

Introduction: Postoperative respiratory failure is a serious problem in patients who undergo general anesthesia. Approximately 90% of mechanically ventilated patients during the surgery may develop atelectasis that leads to perioperative complications. Aim: The aim of this study is to determine whether it is possible to optimize recruitment maneuvers with the use of chest ultrasonography, thus limiting the risk of respiratory complications in patients who undergo general anesthesia. Methodology: The method of incremental increases in positive end-expiratory pressure (PEEP) values with simultaneous continuous ultrasound assessments was employed in mechanically ventilated patients. Results: The study group comprised 100 patients. The employed method allowed for atelectasis reduction in 91.9% of patients. The PEEP necessary to reverse areas of atelectasis averaged 17cmH₂O, with an average peak pressure of 29cmH₂O. The average PEEP that prevented repeat atelectasis was 9cmH₂O. A significant improvement in lung compliance and saturation was obtained. Conclusions: Ultrasound-guided recruitment maneuvers facilitate the patient-based adjustment of the process. Consequently, the reduction in ventilation pressures necessary to aerate intraoperative atelectasis is possible, with the simultaneous reduction in the risk of procedure-related complications.

The Potential Role of Lung-Protective Ventilation in Preventing Postoperative Delirium in Elderly Patients Undergoing Prone Spinal Surgery: A Preliminary Study

BACKGROUND Postoperative delirium (POD) is a frequent complication in elderly patients, usually occurring within a few days after surgery. This study investigated the effect of lung-protective ventilation (LPV) on POD in elderly patients undergoing spinal surgery and the mechanism by which LPV suppresses POD. MATERIAL AND METHODS Seventy-one patients aged ≥65 years were randomized to receive LPV or conventional mechanical ventilation (MV), consisting of intermittent positive pressure ventilation following induction of anesthesia. The tidal volume in patients who received MV was 8 ml/kg predicted body weight (PBW), and the ventilation frequency was 12 times/min. The tidal volume in patients who received LPV was 6 ml/kg PBW, the positive end-expiratory pressure was 5 cmH₂O, and the ventilation frequency was 15 times/min, with a lung recruitment maneuver performed every 30 min. Blood samples were collected immediately before anesthesia induction (T₀), 10 min (T₁) and 60 min (T₂) after turning over, immediately after the operation (T₃), and 15 min after extubation (T₄) for blood gas analysis. Simultaneous cerebral oxygen saturation (rSO₂) and cerebral desaturation were recorded. Preoperative and postoperative serum concentrations of interleukin (IL)-6, IL-10 and glial fibrillary acidic protein (GFAP) were measured by ELISA. POD was assessed by nursing delirium screening score. RESULTS Compared with the MV group, pH was lower and PaCO₂ higher in the LPV group at T₂. In addition PaO₂, SaO₂, and PaO₂/FiO₂ were higher at T₁, and T₄, and rSO₂ was higher at T₃, and T₄ in the LPV than in the MV group (P<0.05 each). Postoperative serum GFAP and IL-6 were lower and IL-10 higher in the LPV group. The incidences of cerebral desaturation and POD were significantly lower in the LPV group (P<0.05). CONCLUSIONS LPV may reduce POD in elderly patients undergoing spinal surgery by inhibiting inflammation and improving cerebral oxygen metabolism.

Intraoperative mechanical ventilation practice in thoracic surgery patients and its association with postoperative pulmonary complications: results of a multicenter prospective observational study

Background

Intraoperative mechanical ventilation may influence postoperative pulmonary complications (PPCs). Current practice during thoracic surgery is not well described.

Methods

This is a post-hoc analysis of the prospective multicenter cross-sectional LAS VEGAS study focusing on patients who underwent thoracic surgery. Consecutive adult patients receiving invasive ventilation during general anesthesia were included in a one-week period in 2013. Baseline characteristics, intraoperative and postoperative data were registered. PPCs were collected as composite endpoint until the 5th postoperative day. Patients were stratified into groups based on the use of one lung ventilation (OLV) or two lung ventilation (TLV), endoscopic vs. non-endoscopic approach and ARISCAT score risk for PPCs. Differences between subgroups were compared using χ² or Fisher exact tests or Student’s t-test. Kaplan–Meier estimates of the cumulative probability of development of PPC and hospital discharge were performed. Cox-proportional hazard models without adjustment for covariates were used to assess the effect of the subgroups on outcome.

Results

From 10,520 patients enrolled in the LAS VEGAS study, 302 patients underwent thoracic procedures and were analyzed. There were no differences in patient characteristics between OLV vs. TLV, or endoscopic vs. open surgery. Patients received V_T of 7.4 ± 1.6 mL/kg, a PEEP of 3.5 ± 2.4 cmH₂O, and driving pressure of 14.4 ± 4.6 cmH₂O. Compared with TLV, patients receiving OLV had lower V_T and higher peak, plateau and driving pressures, higher PEEP and respiratory rate, and received more recruitment maneuvers. There was no difference in the incidence of PPCs in OLV vs. TLV or in endoscopic vs. open procedures. Patients at high risk had a higher incidence of PPCs compared with patients at low risk (48.1% vs. 28.9%; hazard ratio, 1.95; 95% CI 1.05–3.61; p = 0.033). There was no difference in the incidence of severe PPCs. The in-hospital length of stay (LOS) was longer in patients who developed PPCs. Patients undergoing OLV, endoscopic procedures and at low risk for PPC had shorter LOS.

Conclusion

PPCs occurred frequently and prolonged hospital LOS following thoracic surgery. Proportionally large tidal volumes and high driving pressure were commonly used in this sub-population. However, large RCTs are needed to confirm these findings.

Trial registration

This trial was prospectively registered at the Clinical Trial Register (www.clinicaltrials.gov; NCT01601223; registered May 17, 2012.)

Temporal Changes in Ventilator Settings in Patients With Uninjured Lungs: A Systematic Review

In patients with uninjured lungs, increasing evidence indicates that tidal volume (VT) reduction improves outcomes in the intensive care unit (ICU) and in the operating room (OR). However, the degree to which this evidence has translated to clinical changes in ventilator settings for patients with uninjured lungs is unknown. To clarify whether ventilator settings have changed, we searched MEDLINE, Cochrane Central Register of Controlled Trials, and Web of Science for publications on invasive ventilation in ICUs or ORs, excluding those on patients <18 years of age or those with >25% of patients with acute respiratory distress syndrome (ARDS). Our primary end point was temporal change in VT over time. Secondary end points were changes in maximum airway pressure, mean airway pressure, positive end-expiratory pressure, inspiratory oxygen fraction, development of ARDS (ICU studies only), and postoperative pulmonary complications (OR studies only) determined using correlation analysis and linear regression. We identified 96 ICU and 96 OR studies comprising 130,316 patients from 1975 to 2014 and observed that in the ICU, VT size decreased annually by 0.16 mL/kg (-0.19 to -0.12 mL/kg) (P < .001), while positive end-expiratory pressure increased by an average of 0.1 mbar/y (0.02-0.17 mbar/y) (P = .017). In the OR, VT size decreased by 0.09 mL/kg per year (-0.14 to -0.04 mL/kg per year) (P < .001). The change in VTs leveled off in 1995. Other intraoperative ventilator settings did not change in the study period. Incidences of ARDS (ICU studies) and postoperative pulmonary complications (OR studies) also did not change over time. We found that, during a 39-year period, from 1975 to 2014, VTs in clinical studies on mechanical ventilation have decreased significantly in the ICU and in the OR.

Protective ventilation with high versus low positive end-expiratory pressure during one-lung ventilation for thoracic surgery (PROTHOR): study protocol for a randomized controlled trial

BACKGROUND

Postoperative pulmonary complications (PPC) may result in longer duration of in-hospital stay and even mortality. Both thoracic surgery and intraoperative mechanical ventilation settings add considerably to the risk of PPC. It is unclear if one-lung ventilation (OLV) for thoracic surgery with a strategy of intraoperative high positive end-expiratory pressure (PEEP) and recruitment maneuvers (RM) reduces PPC, compared to low PEEP without RM.

METHODS

PROTHOR is an international, multicenter, randomized, controlled, assessor-blinded, two-arm trial initiated by investigators of the PROtective VEntilation NETwork. In total, 2378 patients will be randomly assigned to one of two different intraoperative mechanical ventilation strategies. Investigators screen patients aged 18 years or older, scheduled for open thoracic or video-assisted thoracoscopic surgery under general anesthesia requiring OLV, with a maximal body mass index of 35 kg/m2, and a planned duration of surgery of more than 60 min. Further, the expected duration of OLV shall be longer than two-lung ventilation, and lung separation is planned with a double lumen tube. Patients will be randomly assigned to PEEP of 10 cmH2O with lung RM, or PEEP of 5 cmH2O without RM. During two-lung ventilation tidal volume is set at 7 mL/kg predicted body weight and, during OLV, it will be decreased to 5 mL/kg. The occurrence of PPC will be recorded as a collapsed composite of single adverse pulmonary events and represents the primary endpoint.

DISCUSSION

PROTHOR is the first randomized controlled trial in patients undergoing thoracic surgery with OLV that is adequately powered to compare the effects of intraoperative high PEEP with RM versus low PEEP without RM on PPC. The results of the PROTHOR trial will support anesthesiologists in their decision to set intraoperative PEEP during protective ventilation for OLV in thoracic surgery.

TRIAL REGISTRATION

The trial was registered in clinicaltrials.gov ( NCT02963025 ) on 15 November 2016.

Routine practice in mechanical ventilation in cardiac surgery in Italy

BACKGROUND

Management of mechanical ventilation is a key issue in the prevention of postoperative pulmonary complications (PPCs) and the improvement of surgical outcome. This is especially true in cardiac surgery where the use of the cardiopulmonary bypass (CPB) increases the risk of lung injury. In the last years a growing number of studies have shown that protective ventilation has led to excellent results. However, the literature in this regard is lacking in cardiac surgery and there are no univocal guidelines in this sense. The aim of this survey was to investigate the actual clinical practice about ventilation techniques used in the Italian cardiac surgery centers.

METHODS

A questionnaire of 32-item was sent to 69 Italian cardiac surgery centers, 56 of which return a completed form (81.2%). The questionnaire was assembled by three independent researchers and the final version was e-mailed to all members of the SIAARTI (Italian society of anesthesia resuscitation and intensive care medicine) Study Group on Cardiothoracic and Vascular Anesthesia. The answers were collected using a Google Forms sheet. In case of multiple questionnaires returned from the same center (i.e., different physicians from the same center responded) the head of department was asked to give a definite answer. Furthermore, for the 17 centers who reported multiple questionnaires, no large differences were found between the responses of different doctors belonging to the same center (12.3%±4.2% of discordant answers).

RESULTS

Intraoperatively, patients were ventilated with a tidal volume (TV) of 6-8 mL/kg (91.1% of centers), a positive end-expiration pressure of 3-5 cmH2O (76.8% of centers) and a fraction of inspired oxygen (FiO2) of 50-80% (60.7% of centers). During the CPB, the "stop ventilation" technique was frequently adopted (73.2%). Before the discharge from the intensive care unit (ICU) non-invasive ventilation (NIV) was never applied in 32.1% of the centers, but it was used in 46.4% of patients with postoperative complications.

CONCLUSIONS

This study shows a significant heterogeneity in ventilatory techniques among the Italian centers during CPB, whereas in the other surgical time the majority of the responding centers adopted a protective mechanical ventilation strategy.

Value of preoperative spirometry test in predicting postoperative pulmonary complications in high-risk patients after laparoscopic abdominal surgery

Whether preoperative spirometry in non-thoracic surgery can predict postoperative pulmonary complications (PPCs) is controversial. We investigated whether preoperative spirometry results can predict the occurrence of PPCs in patients who had undergone laparoscopic abdominal surgery. This retrospective observational study analyzed the records of patients who underwent inpatient laparoscopic gastric or colorectal cancer surgery at Seoul National University Bundang Hospital between January 2010 and June 2017. Preoperative spirometry was performed for patients at a high risk of PPCs, such as elderly patients (age >60 years), patients aged <60 years with chronic pulmonary disease, and current smokers. The main outcome was the association between the results of spirometry tests performed within 1 month prior to surgery and the occurrence of PPCs, as determined by multivariable logistic regression analysis. Of the 898 included patients who underwent laparoscopic gastric (372 patients) or colorectal cancer surgery (526 patients), PPC occurred in 117 patients (gastric cancer: 74, colorectal cancer: 43). A 1% greater preoperative forced vital capacity (FVC) was associated with a 2% lower incidence of PPCs after laparoscopic gastric or colorectal cancer surgery (odds ratio: 0.98, 95% confidence interval: 0.97–0.99, P = 0.018). However, the preoperative forced expiratory volume in 1 second (FEV1) (%) and FEV1/FVC (%) were not significantly associated with PPCs (P = 0.059 and P = 0.147, respectively). In conclusion, lower preoperative spirometry FVC, but not FEV1 or FEV1/FVC, may predict PPCs in high-risk patients undergoing laparoscopic abdominal surgery.

Mechanical ventilation management during cardiothoracic surgery: an open challenge

Mechanical ventilation during surgery is a highly complex procedure, particularly in cardiothoracic surgery, where patients need to undergo substantial hemodynamic management, involving large fluid exchanges and pharmacological manipulation of vascular resistance, as well as direct manipulation of the lungs themselves. Cardiothoracic surgery is burdened by a high rate of postoperative pulmonary complication (PPC), comorbidity, and mortality. Recent trials have examined various techniques to preserve lung function, although consensus on best practice has yet to be reached. This might be due to the close relationship between the circulatory and pulmonary systems. The use of a technique designed to prevent pulmonary complication might negatively impact the hemodynamics of an already critical patient. Stress-induced lung injury can occur during surgery for various reasons, some of which have yet to be fully investigated. In cardiac surgery, this damage is mainly ascribed to two events: cardiopulmonary bypass (CPB) and sternotomy. In thoracic surgery, on the other hand, overdistention and permissive hyperoxia, both routinely used on one lung to compensate for the collapse of the other, are generally to blame for lung injury. In recent years "protective" ventilation strategies have been proposed to spare lung parenchyma from stress-induced damage. Despite the growing interest in protective ventilation techniques, there are still no clear international guidelines for mechanical ventilation in cardiothoracic surgery. However, some recent progress has been made, with positive clinical outcomes.

Perioperative lung protective ventilation

Perioperative lung injury is a major source of postoperative morbidity, excess healthcare use, and avoidable mortality. Many potential inciting factors can lead to this condition, including intraoperative ventilator induced lung injury. Questions exist as to whether protective ventilation strategies used in the intensive care unit for patients with acute respiratory distress syndrome are equally beneficial for surgical patients, most of whom do not present with any pre-existing lung pathology. Studied both individually and in combination as a package of intraoperative lung protective ventilation, the use of low tidal volumes, moderate positive end expiratory pressure, and recruitment maneuvers have been shown to improve oxygenation and pulmonary physiology and to reduce postoperative pulmonary complications in at risk patient groups. Further work is needed to define the potential contributions of alternative ventilator strategies, limiting excessive intraoperative oxygen supplementation, use of non-invasive techniques in the postoperative period, and personalized mechanical ventilation. Although the weight of evidence strongly suggests a role for lung protective ventilation in moderate risk patient groups, definitive evidence of its benefit for the general surgical population does not exist. However, given the shift in understanding of what is needed for adequate oxygenation and ventilation under anesthesia, the largely historical arguments against the use of intraoperative lung protective ventilation may soon be outdated, on the basis of its expanding track record of safety and efficacy in multiple settings.

Quick reference tidal volume cards reduce the incidence of large tidal volumes during surgery

Ventilation with large tidal volumes (V _T), greater than 10 ml/kg of predicted body weight (PBW), is associated with worse outcomes in critically ill and surgical patients. We hypothesized that the availability of quick reference cards with proposed V _T ranges specific to gender and different heights would reduce the intraoperative use of large V _T during prolonged abdominal surgery. We compared retrospectively the incidence of median V _T used during prolonged (≥4-h-long) abdominal surgery before ("before") and after ("after") the quick reference V _T cards were made available in all anesthesia machines in operating rooms of a single academic US medical center. We evaluated the effect of the intervention on the primary outcome while adjusting for previously identified risk factors of large V _T use: female gender, obesity (body mass index, BMI > 30), and short height (< 165 cm). The frequency of V _T > 10 ml/kg PBW was 15.1% in the before group and 4.3% in the after group (p < 0.001). The frequency of large V _T used during abdominal surgery was significantly decreased after the intervention even after adjusting for female gender, obesity or short height [adjOR 0.11 (95% CI 0.04-0.30)]. Our quick reference V _T cards significantly reduced the frequency of large V _T use during abdominal surgery.

Continuous Procedural Full-Lung Ventilation During Minimally Invasive Coronary Bypass Grafting

BACKGROUND

In the past, minimally invasive cardiac surgery (MICS)- coronary artery bypass graft surgery (CABG) alternatives have been introduced that dramatically reduce the invasiveness of standard operative procedures while still showing excellent clinical outcomes. However, in patients with high morbidity, reduced lung function impeding single-lung ventilation is one of the major concerns for MICS-CABG procedures, although those patients might reap the largest benefit from a procedure of reduced invasiveness.

METHODS

Here, we describe a simple surgical technique-the fan technique-that allows for continuous full-lung ventilation with unimpeded surgical view during common MICS-CABG procedures. To evaluate the procedural feasibility of this technique, we analyzed intraoperative ventilation measurements of 22 consecutive MICS-CABG patients in whom the fan technique was used.

RESULTS

This study demonstrates a significant improvement of standard respiratory measurements during procedural full-lung ventilation using the fan technique as compared with conventional single-lung ventilation (ventilation pressure 21.4 ± 3.2 versus 26.6 ± 3 mbar, p < 0.001; respiratory rate 13.1 ± 1.4 versus 14.4 ± 2.2 breaths per minute, p < 0.001; minute volume 7.4 ± 1.1 versus 6.2 ± 1 L/min, p < 0.0001; Pao₂ during ventilation 294.9 ± 74.6 versus 153.2 ± 71 mm Hg, p < 0.0001).

CONCLUSIONS

The presented technique may not only enable us to perform MICS-CABG procedures in patients not suitable for single-lung ventilation owing to reduced pulmonary function, but also may soon also become a standard procedure for MICS-CABG surgery, especially with regard to procedures involving complex and time-consuming multivessel revascularizations. However, further studies are strongly warranted to assess whether the fan technique may also decrease postoperative pulmonary complications and benefit clinical outcome indicators.

Effect of low tidal volume with PEEP on respiratory function in infants undergoing one-lung ventilation

BACKGROUND

An increasing number of studies have shown that low tidal volume (TV) with positive end-expiratory pressure (PEEP) offers lung protection during one-lung ventilation (OLV). Considering the unique physiological characteristics of infants, we aimed to determine the feasibility and effect of low TV with PEEP in infants undergoing OLV during thoracoscopy.

PATIENTS AND METHODS

We randomized 60 infants to a conventional group (group I: TV, 8-10 ml/kg; RR, 23-45 bpm; PEEP, 0 cmH₂O) or a low TV with PEEP group (group II: TV, 5-7 ml/kg; RR, 23-45 bpm; PEEP, 4-6 cmH₂O). Arterial blood gas analyses were performed at four time points: 5 min of two-lung ventilation (TLV, T₀), and 20 min, 40 min, and 60 min of OLV (T₁, T₂, T₃); hemodynamic parameters (heart rate, mean blood pressure), temperature, as well as gas exchange (SpO₂ and P_ETCO₂) and ventilation parameters (FiO₂, PEEP, P_max) were recorded simultaneously. Lung compliance and shunt were also calculated.

RESULT

No significant difference was found between both groups at T₀. Compared with T₀, P_ETCO₂, P_max, PaCO₂, lactic acid, and intrapulmonary shunt volume (Qs/Qt) were increased while PaO₂ and respiratory system compliance (Cdyx) were decreased noticeably in both groups at T₁, T₂, and T₃. At T₁, T₂, and T₃, P_max and Qs/Qt were much lower while P_ETCO₂, PaCO₂, and Cdyx were higher in group II than in group I. There was no significant difference in lactic acid and PaO₂ measurements between the two groups at T₁, T₂, and T₃.

CONCLUSION

Low TV with PEEP could be an effective intraoperative ventilation strategy for infants undergoing OLV during video-assisted thoracoscopic surgery and may reduce the risk of lung injury. However, this strategy, as well as the influence of intraoperative hypercapnia on infants, needs further investigation.

Anesthetic Management of the Adult Patient with Concomitant Cardiac and Pulmonary Disease

Several common diseases of the cardiac and pulmonary systems and the interactions of the two in disease and anesthetic management are discussed. Management of these disease processes in isolation is reviewed and how the management of one organ system impacts another is then explored. For example, in a patient with acute lung injury and right heart failure, lung-protective ventilation may directly conflict with strategies to minimize right heart afterload. Such challenging clinical scenarios require appreciation of each disease entity, their appropriate management, and the balance between competing priorities.

Pneumoperitoneum deteriorates intratidal respiratory system mechanics: an observational study in lung-healthy patients

BACKGROUND

Pneumoperitoneum during laparoscopic surgery leads to atelectasis and impairment of oxygenation. Positive end-expiratory pressure (PEEP) is supposed to counteract atelectasis. We hypothesized that the derecruiting effects of pneumoperitoneum would deteriorate the intratidal compliance profile in patients undergoing laparoscopic surgery.

METHODS

In 30 adult patients scheduled for surgery with pneumoperitoneum, respiratory variables were measured during mechanical ventilation. We calculated the dynamic compliance of the respiratory system (C RS) and the intratidal volume-dependent C RS curve using the gliding-SLICE method. The C RS curve was then classified in terms of indicating intratidal recruitment/derecruitment (increasing profile) and overdistension (decreasing profile). During the surgical interventions, the PEEP level was maintained nearly constant at 7 cm H2O. Data are expressed as mean [confidence interval].

RESULTS

Baseline C RS was 60 [54-67] mL cm H2O-1. Application of pneumoperitoneum decreased C RS to 40 [37-43] mL cm H2O-1 which partially recovered to 54 [50-59] mL cm H2O-1 (P < 0.001) after removal but remained below the value measured before pneumoperitoneum (P < 0.001). Baseline compliance profiles indicated intratidal recruitment/derecruitment in 48 % patients. After induction of pneumoperitoneum, intratidal recruitment/derecruitment was indicated in 93 % patients (P < 0.01), and after removal intratidal recruitment/derecruitment was indicated in 59 % patients. Compliance profiles showing overdistension were not observed.

CONCLUSIONS

Analyses of the intratidal compliance profiles reveal that pneumoperitoneum during laparoscopic surgery causes intratidal recruitment/derecruitment which partly persists after its removal. The analysis of the intratidal volume-dependent C RS profiles could be used to guide intraoperative PEEP adjustments during elevated intraabdominal pressure.

Perioperative "remote" acute lung injury: recent update

Perioperative acute lung injury (ALI) is a syndrome characterised by hypoxia and chest radiograph changes. It is a serious post-operative complication, associated with considerable mortality and morbidity. In addition to mechanical ventilation, remote organ insult could also trigger systemic responses which induce ALI. Currently, there are limited treatment options available beyond conservative respiratory support. However, increasing understanding of the pathophysiology of ALI and the biochemical pathways involved will aid the development of novel treatments and help to improve patient outcome as well as to reduce cost to the health service. In this review we will discuss the epidemiology of peri-operative ALI; the cellular and molecular mechanisms involved on the pathological process; the clinical considerations in preventing and managing perioperative ALI and the potential future treatment options.

Preoxygenation and intraoperative ventilation strategies in obese patients: a comprehensive review

PURPOSE OF REVIEW

Obesity along with its pathophysiological changes increases risk of intraoperative and perioperative respiratory complications. The aim of this review is to highlight recent updates in preoxygenation techniques and intraoperative ventilation strategies in obese patients to optimize gas exchange and pulmonary mechanics and reduce pulmonary complications.

RECENT FINDINGS

There is no gold standard in preoxygenation or intraoperative ventilatory management protocol for obese patients. Preoxygenation in head up or sitting position has been shown to be superior to supine position. Apneic oxygenation and use of continuous positive airway pressure increases safe apnea duration. Recent evidence encourages the intraoperative use of low tidal volume to improve oxygenation and lung compliance without adverse effects. Contrary to nonobese patients, some studies have reported the beneficial effect of recruitment maneuvers and positive end-expiratory pressure in obese patients. No difference has been observed between volume controlled and pressure controlled ventilation.

SUMMARY

The ideal ventilatory plan for obese patients is indeterminate. A multimodal preoxygenation and intraoperative ventilation plan is helpful in obese patients to reduce perioperative respiratory complications. More studies are needed to identify the role of low tidal volume, positive end-expiratory pressure, and recruitment maneuvers in obese patients undergoing general anesthesia.

Clinical Practice Guideline of Acute Respiratory Distress Syndrome

There is no well-stated practical guideline for mechanically ventilated patients with or without acute respiratory distress syndrome (ARDS). We generate strong (1) and weak (2) grade of recommendations based on high (A), moderate (B) and low (C) grade in the quality of evidence. In patients with ARDS, we recommend low tidal volume ventilation (1A) and prone position if it is not contraindicated (1B) to reduce their mortality. However, we did not support high-frequency oscillatory ventilation (1B) and inhaled nitric oxide (1A) as a standard treatment. We also suggest high positive end-expiratory pressure (2B), extracorporeal membrane oxygenation as a rescue therapy (2C), and neuromuscular blockage for 48 hours after starting mechanical ventilation (2B). The application of recruitment maneuver may reduce mortality (2B), however, the use of systemic steroids cannot reduce mortality (2B). In mechanically ventilated patients, we recommend light sedation (1B) and low tidal volume even without ARDS (1B) and suggest lung protective ventilation strategy during the operation to lower the incidence of lung complications including ARDS (2B). Early tracheostomy in mechanically ventilated patients can be performed only in limited patients (2A). In conclusion, of 12 recommendations, nine were in the management of ARDS, and three for mechanically ventilated patients.