The effect of intraoperative lung protective ventilation vs conventional ventilation, on postoperative pulmonary complications after cardiopulmonary bypass

Open-lung ventilation versus no ventilation during cardiopulmonary bypass in an innovative animal model of heart transplantation

Open-lung ventilation during cardiopulmonary bypass (CPB) in patients undergoing heart transplantation (HTx) is a potential strategy to mitigate postoperative acute respiratory distress syndrome (ARDS). We utilized an ovine HTx model to investigate whether open-lung ventilation during CPB reduces postoperative lung damage and complications. Eighteen sheep from an ovine HTx model were included, with ventilatory interventions randomly assigned during CPB: the OPENVENT group received low tidal volume (VT) of 3 mL/kg and positive end-expiratory pressure (PEEP) of 8 cm H20, while no ventilation was provided in the NOVENT group as per standard of care. The recipient sheep were monitored for 6 h post-surgery. The primary outcome was histological lung damage, scored at the end of the study. Secondary outcomes included pulmonary shunt, driving pressure, hemodynamics and inflammatory lung infiltration. All animals completed the study. The OPENVENT group showed significantly lower histological lung damage versus the NOVENT group (0.22 vs 0.27, p = 0.042) and lower pulmonary shunt (19.2 vs 32.1%, p = 0.001). In addition, the OPENVENT group exhibited a reduced driving pressure (9.6 cm H2O vs. 12.8 cm H2O, p = 0.039), lower neutrophil (5.25% vs 7.97%, p ≤ 0.001) and macrophage infiltrations (11.1% vs 19.6%, p < 0.001). No significant differences were observed in hemodynamic parameters. In an ovine model of HTx, open-lung ventilation during CPB significantly reduced lung histological injury and inflammatory infiltration. This highlights the value of an open-lung approach during CPB and emphasizes the need for further clinical evidence to decrease risks of lung injury in HTx patients.

Perioperative Optimization of the Cardiac Surgical Patient

Perioperative optimization of cardiac surgical patients is imperative to reduce complications, utilize health care resources efficiently, and improve patient recovery and quality of life. Standardized application of evidence-based best practices can lead to better outcomes. Although many practices should be applied universally to all patients, there are also opportunities along the surgical journey to identify patients who will benefit from additional interventions that will further ameliorate their recovery. Enhanced recovery programs aim to bundle several process elements in a standardized fashion to optimize outcomes after cardiac surgery. A foundational concept of enhanced recovery is attaining a better postsurgical end point for patients, in less time, through achievement and maintenance in their greatest possible physiologic, functional, and psychological state. Perioperative optimization is a broad topic, spanning multiple phases of care and involving a variety of medical specialties and nonphysician health care providers. In this review we highlight a variety of perioperative care topics, in which a comprehensive approach to patient care can lead to improved results for patients, providers, and the health care system. A particular focus on patient-centred care is included. Although existing evidence supports all of the elements reviewed, most require further improvements in implementation, as well as additional research, before their full potential and usefulness can be determined.

2021 ACC/AHA/SCAI Guideline for Coronary Artery Revascularization: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

The guideline for coronary artery revascularization replaces the 2011 coronary artery bypass graft surgery and the 2011 and 2015 percutaneous coronary intervention guidelines, providing a patient-centric approach to guide clinicians in the treatment of patients with significant coronary artery disease undergoing coronary revascularization as well as the supporting documentation to encourage their use.

METHODS

A comprehensive literature search was conducted from May 2019 to September 2019, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Collaboration, CINHL Complete, and other relevant databases. Additional relevant studies, published through May 2021, were also considered.

STRUCTURE

Coronary artery disease remains a leading cause of morbidity and mortality globally. Coronary revascularization is an important therapeutic option when managing patients with coronary artery disease. The 2021 coronary artery revascularization guideline provides recommendations based on contemporary evidence for the treatment of these patients. The recommendations present an evidence-based approach to managing patients with coronary artery disease who are being considered for coronary revascularization, with the intent to improve quality of care and align with patients' interests.

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.

Phrenic nerve block during nonintubated video-assisted thoracoscopic surgery: a single-centre, double-blind, randomized controlled trial

There has been interest in the use of nonintubated techniques for video-assisted thoracoscopic surgery (VATS) in both awake and sedated patients. The authors’ centre developed a nonintubated technique with spontaneous ventilation for use in a patient under general anaesthesia using a phrenic nerve block. This treatment was compared with a case-matched control group. The authors believe that this technique is beneficial for optimizing anaesthesia for patients undergoing VATS. The patients were randomly allocated (1:1) to the phrenic nerve block (PNB) group and the control group. Both groups of patients received a laryngeal mask airway (LMA) that was inserted after anaesthetic induction, which permitted spontaneous ventilation and local anaesthesia in the forms of a paravertebral nerve block, a PNB and a vagal nerve block. However, the patients in the PNB group underwent procedures with 2% lidocaine, whereas saline was used in the control group. The primary outcome included the propofol doses. Secondary outcomes included the number of propofol boluses, systolic blood pressure (SBP), pH values of arterial blood gas and lactate (LAC), length of LMA pulled out, length of hospital stay (length of time from the operation to the time of discharge) and complications after 1 month. Intraoperatively, there were increases in lactate (F = 12.31, P = 0.001) in the PNB group. There was less propofol (49.20 ± 8.73 vs. 57.20 ± 4.12, P = 0.000), fewer propofol boluses (P = 0.002), a lower pH of arterial blood gas (F = 7.98, P = 0.006) and shorter hospital stays (4.10 ± 1.39 vs. 5.40 ± 1.22, P = 0.000) in the PNB group. There were no statistically significant differences in the length of the LMA pulled out, SBP or complications after 1 month between the groups. PNB optimizes the anaesthesia of nonintubated VATS.

Recruitment maneuvers to reduce pulmonary atelectasis after cardiac surgery: A meta-analysis of randomized trials

BACKGROUND

Pulmonary atelectasis is a common postoperative complication that may lead to intrapulmonary shunt, refractory hypoxemia, and respiratory distress. Recruitment maneuvers may relieve pulmonary atelectasis in patients undergoing cardiac surgery. We conducted a meta-analysis of randomized controlled trials to evaluate the effectiveness of recruitment maneuvers in these patients.

METHODS

We conducted a search in PubMed, Embase, Cochrane Library, and the ClinicalTrials.gov registry for trials published before March 2020. Individual effect sizes were standardized, and a meta-analysis was performed to calculate a pooled effect size by using random-effects models. Pulmonary atelectasis was assessed postoperatively. Secondary outcomes included hypoxic events, arterial oxygen tension (Pao₂)/inspired oxygen fraction (Fio₂) ratio, cardiac index, mean arterial pressure, and postoperative complications including pneumothorax and pneumonia.

RESULTS

We reviewed 16 trials involving 1455 patients. Patients receiving recruitment maneuvers had a reduced incidence of pulmonary atelectasis (group with recruited pressure >40 cmH₂O: risk ratio [RR], 0.20; 95% confidence interval [CI], 0.07-0.57; group with recruited pressure <40 cmH₂O: RR, 0.54; 95% CI, 0.33-0.89), reduced incidence of hypoxic events (RR, 0.23; 95% CI, 0.14-0.37), reduced incidence of pneumonia (RR, 0.42; 95% CI, 0.18-0.95), and improved Pao₂/Fio₂ ratio (weighted mean difference [WMD]; 58.87, 95% CI, 31.24-86.50) without disturbing the cardiac index (WMD, 0.22; 95% CI, -0.18 to 0.61) or mean arterial pressure (WMD, -0.30, 95% CI, -3.19 to 2.59) as compared with those who received conventional mechanical ventilation. The incidence of pneumothorax was nonsignificant between the groups.

CONCLUSIONS

Recruitment maneuvers may reduce postoperative pulmonary atelectasis, hypoxic events, and pneumonia and improve Pao₂/Fio₂ ratios without hemodynamic disturbance in patients undergoing cardiac surgery.

A clinical trial of volume- versus pressure-controlled intraoperative ventilation during laparoscopic bariatric surgeries

BACKGROUND

Intra-operative ventilation is often challenging in patients with morbid obesity undergoing bariatric surgery.

OBJECTIVES

To test the noninferiority of pressure-controlled ventilation (PCV) to volume-controlled ventilation (VCV) in respiratory mechanics.

SETTING

Bariatric Surgery Center, Iran.

METHODS

In a randomized open-labeled clinical trial, 66 individuals with morbid obesity undergoing laparoscopic bariatric surgeries underwent intraoperative ventilation with either PCV or VCV. The measurements taken were peak and mean airway pressures (H₂O), partial pressure of arterial oxygen (PaO₂), partial pressure of arterial carbon dioxide (PaCO₂) and end-tidal carbon dioxide (CO₂). We additionally collected pulse-oximetric oxygen saturation, inspiratory concentration of oxygen (FiO₂), and hemodynamic variables. Data were analyzed with repeated measures over the time of intubation, after peritoneal insufflation, and every 15 minutes, thereafter up to one hour.

RESULTS

PCV mode was successful to sustain adequate ventilation in 97% of the patients, which was similar to the 94% success rate of the VCV mode. Peak airway pressure increased 6 cmH₂O and end-tidal CO₂ rose by 5 mm Hg after abdominal insufflation in both groups (P = .850 and .376). Alveolar-arterial oxygen gradient similarly increased within 30 minutes after tracheal intubation both in PCV and VCV groups, with small trend of being higher in the VCV group. The ratio of dead space to tidal volumes (VD/VT) did not have a meaningful change (P = .724).

CONCLUSION

PCV was noninferior to VCV during laparoscopic bariatric surgery. Either mode of ventilation could be alternatively used during the anesthesia care of these patients.

Effect of Retrograde Autologous Blood Priming of Cardiopulmonary Bypass on Hemodynamic Parameters and Pulmonary Mechanics in Pediatric Cardiac Surgery: A Randomized Clinical Study

The present study aimed to assess the impact of retrograde autologous priming (RAP) on hemodynamics and pulmonary mechanics in children subjected to cardiothoracic surgery. This prospective randomized study analyzed the clinical records of 124 children with risk adjustment in congenital heart surgery-1 left to right lesions subjected to cardiac surgery. They comprised 64 patients in RAP group and 60 patients in the conventional priming group. The preoperative, intraoperative and postoperative data of the studied patients were reported. The outcome measures included hematocrit (Hct) value, blood gases, lung mechanics parameters, transfusion needs, ICU stay, postoperative complications and mortality. Preoperatively, there were no significant differences between the studied groups regarding the demographic data, underlying lesions, laboratory data, blood gases and pulmonary mechanics parameters. Intraoperatively, RAP group patients had significantly lower amount of blood loss, less frequent need to packed red blood cells (RBC)s transfusion and better Hct values when compared with the control group. Postoperatively, RAP group patients had significantly higher Hct% at ICU arrival, significantly better pulmonary mechanics parameters and significantly shorter duration on mechanical ventilation. RAP in children older than 12 months subjected to cardiac surgery for risk adjustment in congenital heart surgery-1 left to right lesions is associated with less transfusion needs and better pulmonary mechanics.

Anesthetic considerations and goals in robotic pediatric surgery: a narrative review

The morphosis from open surgeries to minimally invasive procedures is in greater part owing to the development of robotics. There has been a hiking popularity of robotic assistance for surgeries in recent years. Though a minimally invasive approach for surgery, it poses major challenges for an anesthesiologist that compound further for pediatric patients. The need of the hour for an anesthesiologist is to have a scrupulous knowledge and understanding of the associated anatomical and physiological considerations in case of pediatric patients. Major anesthetic concerns include restricted patient access, physiologic changes of pneumoperitoneum and different operative positions, risk of hypothermia, efficient fluid and peri-operative pain management. Timely anticipation, cautious observation for peri-operative complications and quick intervention to manage the same are warranted to provide high-quality anesthetic care. This simply implies that as robotic surgery plans to stretch up-to zenith, anesthesiologists shall strive to ace their part in robotic pediatric anesthesia as well. With an efficient and dynamic teamwork, robotic-assisted surgeries hold the potential to turn wonders for the future of surgery.

Effect of intraoperative lung-protective mechanical ventilation on pulmonary oxygenation function and postoperative pulmonary complications after laparoscopic radical gastrectomy

This study aimed to observe the effects of lung-protective ventilation (LPV) on oxygenation index (OI) and postoperative pulmonary complications (PPCs) after laparoscopic radical gastrectomy in middle-aged and elderly patients. A total of 120 patients who were scheduled to undergo laparoscopic radical gastrectomy with an expected time of >3 h were randomly divided into conventional ventilation (CV group) with tidal volume (TV) of 10 mL/kg without positive end-expiratory pressure (PEEP), and lung-protective ventilation (PV group) with 7 mL/kg TV and personal level of PEEP with regular recruitment maneuver every 30 min. Measurements of OI, modified clinical pulmonary infection score (mCPIS), and PPCs were assessed during the perioperative period. Fifty-seven patients in the CV group and 58 in the PV group participated in the data analysis. Patients in the PV group showed better pulmonary dynamic compliance, OI, and peripheral capillary oxygen saturation during and after surgery. The mCPIS was significantly lower in the PV group than in the CV group after surgery. The incidence rate of PPCs was lower in the PV group than in the CV group and the difference was significant in patients whose ventilation time was longer than 6 h in both groups. LPV during laparoscopic radical gastrectomy significantly improved pulmonary oxygenation function and reduced postoperative mCPIS and the incidence of PPCs during the early period after surgery of middle-aged and elderly patients, especially patients whose mechanical ventilation time was longer than 6 h.

Prevalence and Risk Factors of Hypoxemia after Coronary Artery Bypass Grafting: The Time to Change Our Conceptions

Background: Acute hypoxemia is the main characteristic of acute respiratory distress syndrome (ARDS), which is one of the most critical complications of coronary artery bypass grafting (CABG). Given the dearth of data on acute hypoxemia, we sought to determine its prevalence and risk factors among post-CABG patients. Methods: This cross-sectional study was conducted on on-pump CABG patients in Tehran Heart Center in 2 consecutive months in 2012. The effects of arterial blood gas variables, age, gender, the duration of the pump and cross-clamping, the ejection fraction, the creatinine level, and the body mass index on the prevalence of hypoxemia at the cutoff points of ARDS and acute lung injury were assessed. Results: Out of a total of 232 patients who remained in the study, 174 (75.0%) cases were male. The mean age was 60.60±9.42 years, and the mean body mass index was 27.15±3.93 kg/m². None of the patients expired during the current admission. The ratio of partial pressure arterial oxygen to the fraction of inspired oxygen (PaO₂/FiO₂) 1 hour after admission to the intensive care unit (ICU), before extubation, and at 4 hours after extubation was less than 300 mmHg in 66.6%, 72.2%, and 86.6% of the patients and less than 200 mmHg in 20.8% 17.7%, and 30.2% of the patients, respectively. Among the different variables, only a heavier weight was associated with a PaO₂/FiO₂ ratio of less than 300 mmHg at 1 hour after ICU admission and at 4 hours after extubation (P=0.001). A rise in the cross-clamp time showed a significant association with the risk of a PaO₂/FiO₂ ratio of less than 200 mmHg at 4 hours after extubation (P=0.014). Conclusion: This study shows that hypoxemia following CABG is very common in the first 48 postoperative hours, although it is a benign and transient event. The high prevalence may affect the accuracy of the ARDS criteria and their positive or negative predictive value.

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.

Current and emerging pharmacotherapy for the treatment of infections following open-heart surgery

INTRODUCTION

Patients undergoing open-heart surgery may suffer from postoperative complications, including severe infections. Antimicrobials to treat infectious complications in this population should be selected thoughtfully, taking into account three different and fundamental issues: (i) the site of infection; (ii) the suspected or proven causative agent and its susceptibility pattern; and (iii) the risk of suboptimal pharmacokinetic characteristics and potential toxicity of the chosen drug/s.

AREAS COVERED

The present narrative review summarizes the current and future antimicrobial options for the treatment of infections developing after open-heart surgery.

EXPERT OPINION

The pharmacological treatment of infections developing in cardiac surgery patients poses peculiar challenges, including the need for an active empirical therapy for severe events such as bloodstream infections, deep sternal wound infections, or early-onset postoperative prosthetic endocarditis. In addition, the risk for multidrug-resistant pathogens should also be taken into account in endemic areas. A multidisciplinary evaluation on a patient-by-patient basis, deeply involving infectious diseases specialists and cardiothoracic surgeons, remains essential for appropriately balancing both short-term and long-term risks and benefits of any possible surgical reintervention in combination with adequate pharmacotherapy.