Pulmonary Complications After Cardiac Surgery

Comparison of pulmonary complications in patients undergoing transcatheter aortic valve implantation versus open aortic valve replacement

OBJECTIVE

The purpose of this study was to investigate and compare the differences in postoperative pulmonary complications in patients undergoing aortic valve replacement by open repair (OAVR) versus those undergoing transcatheter aortic valve implantation by the transapical approach (TAVI-A) or transfemoral approach (TAVI-F).

DESIGN

A retrospective review of data from aortic valve replacement patients.

SETTING

A private, non-profit hospital.

PARTICIPANTS

Thirty patients with severe aortic stenosis requiring surgical replacement.

INTERVENTIONS

Data collected from TAVI-F, TAVI-A, and OAVR patient charts.

MATERIALS AND METHODS

Patients were divided into 3 groups: 10 patients undergoing OAVR, 10 patients undergoing TAVI-F, and 10 patients undergoing TAVI-A. Pulmonary complications and length of stay were recorded and analyzed. The TAVI-F group had the lowest number of total pulmonary complications per patient (1.0±0.667) compared to the OAVR group (1.8±0.789, p = 0.04) and TAVI-A group (2.0±1.054, p = 0.02). The most frequent complication was atelectasis. TAVI-F patients spent the least amount of time on the ventilator (TAVI-F median 2.6, IQR 4.8 h, TAVI-A median 4.9, IQR 7.6 h, and OAVR median 6.6, IQR 17.3 h, p = 0.02) and were discharged in half the time of the other groups (TAVI-F median 3.2, IQR 1.3 days, TAVI-A median 5.6, IQR 3.5 days, OAVR median 6.1, IQR 4.6 days, p = 0.008).

CONCLUSIONS

Due to the high incidence of multiple comorbidities and increased age, it is important to take into consideration the risk of pulmonary complications when choosing the surgical and anesthetic approach to TAVI in this high-risk group of patients.

Effect of inspiratory muscle training before cardiac surgery in routine care

BACKGROUND

Inspiratory muscle training (IMT) before cardiac surgery has proved to be a promising intervention to reduce postoperative pneumonia in a randomized controlled trial setting. Effects of IMT in routine care have not been reported.

OBJECTIVE

The purpose of this study was to investigate the effect of IMT before cardiac surgery on postoperative pneumonia in routine care at a Dutch university medical center using propensity scoring.

DESIGN

This was an observational cohort study.

METHODS

All candidates for cardiac surgery were preoperatively stratified by a physical therapist for low risk or high risk for postoperative pulmonary complications. Patients at high risk either engaged in an unsupervised IMT program (20 minutes a day) at home for at least 2 weeks before surgery (group 1) or received usual care (no IMT) (group 2). Results in terms of outcome measures were adjusted with propensity scores to reduce bias caused by nonrandom treatment assignment.

RESULTS

The results showed that of the 94 patients at high risk in group 1, 1 patient (1.1%) developed a postoperative pneumonia. In group 2, 8 out of the 252 patients at high risk (3.2%) developed this pulmonary complication (adjusted odds ratio=0.34, 95% confidence interval=0.04-3.38). No significant differences were found regarding median (25th-75th percentile) ventilation time (7 [5-9] hours versus 7 [5-10] hours), length of stay in the intensive care unit (23 [21-24] hours versus 23 [21-25] hours), or total postoperative length of stay (7 [6-11] days versus 7 [5-9] days).

LIMITATIONS

The most important limitations of this study were confounding, incomplete data collection, and a low incidence of the primary outcome.

CONCLUSIONS

Propensity scoring is believed to be a valuable tool of great potential interest to researchers in the field of observational studies. Whether IMT in routine care resulted in less postoperative pneumonia cannot be concluded.

Objectifying acupuncture effects by lung function and numeric rating scale in patients undergoing heart surgery

Rationale. Poststernotomy pain and impaired breathing are common clinical problems in early postoperative care following heart surgery. Insufficiently treated pain increases the risk of pulmonary complications. High-dose opioids are used for pain management, but they may cause side effects such as respiratory depression. Study Design. We performed a prospective, randomized, controlled, observer-blinded, three-armed clinical trial with 100 patients. Group 1 (n = 33) and Group 2 (n = 34) received one 20 min session of standardized acupuncture treatment with two different sets of acupoints. Group 3 (n = 33) served as standard analgesia control without additional intervention. Results. Primary endpoint analysis revealed a statistically significant analgesic effect for both acupuncture treatments. Group 1 showed a mean percentile pain reduction (PPR) of 18% (SD 19, P < 0.001). Group 2 yielded a mean PPR of 71% (SD 13, P < 0.001). In Group 1, acupuncture resulted in a mean forced vital capacity (FVC) increase of 30 cm(3) (SD 73) without statistical significance (P = 0.303). In Group 2, posttreatment FVC showed a significant increase of 306 cm(3) (SD 215, P < 0.001). Conclusion. Acupuncture revealed specific analgesic effects after sternotomy. Objective measurement of poststernotomy pain via lung function test was possible.

Risk factors for pulmonary complications following cardiac surgery with cardiopulmonary bypass

BACKGROUND

Pulmonary complications following cardiac surgery with cardiopulmonary bypass (CPB) are often associated with significant morbidity and mortality. However, few reports have focused on evaluating intra- and post-operative independent risk factors for pulmonary complications following cardiac surgery with CPB. This study aimed to evaluate peri-operative independent risk factors for postoperative pulmonary complications through investigating and analyzing 2056 adult patients undergoing cardiac surgery with CPB.

METHODS

From January 2005 to December 2012, the relevant pre-, intra-, and post-operative data of adult patients undergoing cardiac surgery with CPB in the department of cardiovascular surgery of Tongji Hospital of Tongji University in Shanghai were investigated and retrospectively analyzed. The independent risk factors for pulmonary complications following cardiac surgery with CPB were obtained through descriptive analysis and then logistic regression analysis.

RESULTS

One hundred and forty-three adult patients suffered from pulmonary complications following cardiac surgery with CPB, with an incidence of 6.96%. Through descriptive analysis and then logistic regression, independent risk factors for postoperative pulmonary complications were as follows: older age (>65 years) (OR=3.31, 95%CI 1.71-7.13), preoperative congestive heart failure (OR=2.95, 95%CI 1.41-5.84), preoperative arterial oxygenation (PaO2) (OR=0.67, 95%CI 0.33-0.85), duration of CPB (OR=3.15, 95%CI 1.55-6.21), intra-operative phrenic nerve injury (OR=4.59, 95%CI 2.52-9.24), and postoperative acute kidney injury (OR=3.21, 95%CI 1.91-6.67). Postoperative pulmonary complication was not a risk factor for hospital death (OR=2.10, 95%CI 0.89-4.33).

CONCLUSIONS

A variety of peri-operative factors increased the incidence of pulmonary complications following cardiac surgery with cardiopulmonary bypass.

Preoperative physical therapy for elective cardiac surgery patients

BACKGROUND

After cardiac surgery, physical therapy is a routine procedure delivered with the aim of preventing postoperative pulmonary complications.

OBJECTIVES

To determine if preoperative physical therapy with an exercise component can prevent postoperative pulmonary complications in cardiac surgery patients, and to evaluate which type of patient benefits and which type of physical therapy is most effective.

SEARCH METHODS

Searches were run on the Cochrane Central Register of Controlled Trials (CENTRAL) on the Cochrane Library (2011, Issue 12 ); MEDLINE (1966 to 12 December 2011); EMBASE (1980 to week 49, 2011); the Physical Therapy Evidence Database (PEDro) (to 12 December 2011) and CINAHL (1982 to 12 December 2011).

SELECTION CRITERIA

Randomised controlled trials or quasi-randomised trials comparing preoperative physical therapy with no preoperative physical therapy or sham therapy in adult patients undergoing elective cardiac surgery.

DATA COLLECTION AND ANALYSIS

Data were collected on the type of study, participants, treatments used, primary outcomes (postoperative pulmonary complications grade 2 to 4: atelectasis, pneumonia, pneumothorax, mechanical ventilation > 48 hours, all-cause death, adverse events) and secondary outcomes (length of hospital stay, physical function measures, health-related quality of life, respiratory death, costs). Data were extracted by one review author and checked by a second review author. Review Manager 5.1 software was used for the analysis.

MAIN RESULTS

Eight randomised controlled trials with 856 patients were included. Three studies used a mixed intervention (including either aerobic exercises or breathing exercises); five studies used inspiratory muscle training. Only one study used sham training in the controls. Patients that received preoperative physical therapy had a reduced risk of postoperative atelectasis (four studies including 379 participants, relative risk (RR) 0.52; 95% CI 0.32 to 0.87; P = 0.01) and pneumonia (five studies including 448 participants, RR 0.45; 95% CI 0.24 to 0.83; P = 0.01) but not of pneumothorax (one study with 45 participants, RR 0.12; 95% CI 0.01 to 2.11; P = 0.15) or mechanical ventilation for > 48 hours after surgery (two studies with 306 participants, RR 0.55; 95% CI 0.03 to 9.20; P = 0.68). Postoperative death from all causes did not differ between groups (three studies with 552 participants, RR 0.66; 95% CI 0.02 to 18.48; P = 0.81). Adverse events were not detected in the three studies that reported on them. The length of postoperative hospital stay was significantly shorter in experimental patients versus controls (three studies with 347 participants, mean difference -3.21 days; 95% CI -5.73 to -0.69; P = 0.01). One study reported a reduced physical function measure on the six-minute walking test in experimental patients compared to controls. One other study reported a better health-related quality of life in experimental patients compared to controls. Postoperative death from respiratory causes did not differ between groups (one study with 276 participants, RR 0.14; 95% CI 0.01 to 2.70; P = 0.19). Cost data were not reported on.

AUTHORS' CONCLUSIONS

Evidence derived from small trials suggests that preoperative physical therapy reduces postoperative pulmonary complications (atelectasis and pneumonia) and length of hospital stay in patients undergoing elective cardiac surgery. There is a lack of evidence that preoperative physical therapy reduces postoperative pneumothorax, prolonged mechanical ventilation or all-cause deaths.

Effect of bronchodilator treatment on the incidence of postoperative atrial fibrillation after cardiac surgery

OBJECTIVE

We sought to examine the effects of bronchodilator treatment on the incidence of postoperative atrial fibrillation (POAF) after cardiac surgery.

METHODS

A cross-sectional design using a retrospective chart review was performed in patients who underwent cardiac surgery. Those who had previous atrial fibrillation or preoperative bronchodilator treatment were excluded from the final sample (n = 506). The Statistical Package for the Social Sciences (SPSS, Inc., Chicago, IL) was used for statistical analyses.

RESULTS

The incidence of POAF in this study was 27.9%, and was associated with age (P < .01) and type of cardiac surgery (P < .05), indicating that increasing age, and combined cardiac surgery were more likely to precipitate POAF. Bronchodilator treatment did not increase POAF. However, combined therapy significantly (P < .01) precipitated more POAF (48.7%) than did albuterol (21.4%) or levalbuterol (18.5%).

CONCLUSIONS

Postoperative atrial fibrillation continues to be a common complication after cardiac surgery. Bronchodilator treatment with either albuterol or levalbuterol did not precipitate POAF, unless both agents were given to the same patients postoperatively.

Bronchial asthma

PURPOSE OF REVIEW

The aim of this review is to underline the need for an adequate clinical and functional evaluation of respiratory function and asthma control in patients undergoing surgical procedures requiring general anesthesia to obtain useful information for an adequate preoperative pharmacological approach.

RECENT FINDINGS

It has been shown that baseline uncontrolled clinical/functional conditions of airways represent the most important risk factors for perioperative bronchospasm. In nonemergency conditions, asthma patients should undergo clinical/functional assessment at least 1 week before the surgery intervention to obtain, the better feasible control of asthma symptoms in the single patient. Some simple preoperative information given by the patient in preoperative consultation may be sufficient to identify individuals with uncontrolled or poor controlled asthmatic conditions. Spirometric evaluation is essential in individuals with poor control of symptoms, as well as in those patients with uncertain anamnestic data or limited perception of respiratory symptoms, and in those requiring lung resection.

SUMMARY

A better control of asthma must be considered the 'gold standard' for a patient at 'a reasonable low risk' to develop perioperative/postoperative bronchospasm. International consensus promoted by pulmonologists, anesthesiologists, and allergists might be useful to define a better diagnostic and therapeutic approach.

Phase I of cardiac rehabilitation: A new challenge for evidence based physiotherapy

Cardiac rehabilitation protocols applied during the in-hospital phase (phase I) are subjective and their results are contested when evaluated considering what should be the three basic principles of exercise prescription: specificity, overload and reversibility. In this review, we focus on the problems associated with the models of exercise prescription applied at this early stage in-hospital and adopted today, especially the lack of clinical studies demonstrating its effectiveness. Moreover, we present the concept of "periodization" as a useful tool in the search for better results.

Assessment of pulmonary function tests in cardiac patients

This study was aimed to assess the pulmonary function tests (PFTs) in cardiac patients; with ischemic or rheumatic heart diseases as well as in patients who underwent coronary artery bypass graft (CABG) or valvular procedures. For the forty eligible participants, the pulmonary function was measured using the spirometry test before and after the cardiac surgery. Data collection sheet was used for the patient's demographic and intra-operative information. Cardiac diseases and surgeries had restrictive negative impact on PFTs. Before surgery, vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), ratio between FEV1 and FVC, and maximum voluntary ventilation (MVV) recorded lower values for rheumatic patients than ischemic patients (P values were 0.01, 0.005, 0.0001, 0.031, and 0.035, respectively). Moreover, patients who underwent valvular surgery had lower PFTs than patients who underwent CABG with significant differences for VC, FVC, FEV1, and MVV tests (P values were 0.043, 0.011, 0.040, and 0.020, respectively). No definite causative factor appeared to be responsible for those results although mechanical deficiency and incisional chest pain caused by cardiac surgery are doubtful. More comprehensive investigation is required to resolve the case.

The effects of preoperative exercise therapy on postoperative outcome: a systematic review

OBJECTIVE

To summarize the current evidence on the effects of preoperative exercise therapy in patients awaiting invasive surgery on postoperative complication rate and length of hospital stay.

DATA SOURCES

A primary search of relevant key terms was conducted in the electronic databases of PubMed, EMBASE, PEDro and CINAHL.

REVIEW METHODS

Studies were included if they were controlled trials evaluating the effects of preoperative exercise therapy on postoperative complication rate and length of hospital stay. The methodological quality of included studies was independently assessed by two reviewers using the PEDro scale. Statistical pooling was performed when studies were comparable in terms of patient population and outcome measures. Results were separately described if pooling was not possible.

RESULTS

Twelve studies of patients undergoing joint replacement, cardiac or abdominal surgery were included. The PEDro scores ranged from 4 to 8 points. Preoperative exercise therapy consisting of inspiratory muscle training or exercise training prior to cardiac or abdominal surgery led to a shorter hospital stay and reduced postoperative complication rates. By contrast, length of hospital stay and complication rates of patients after joint replacement surgery were not significantly affected by preoperative exercise therapy consisting of strength and/or mobility training.

CONCLUSION

Preoperative exercise therapy can be effective for reducing postoperative complication rates and length of hospital stay after cardiac or abdominal surgery. More research on the utility of preoperative exercise therapy and its long-term effects is needed as well as insight in the benefits of using risk models.

Risk factors for late extubation after coronary artery bypass grafting

OBJECTIVE

To evaluate the independent risk factors for late extubation after coronary artery bypass grafting (CABG).

METHODS

Preoperative, intraoperative, and postoperative characteristics of patients undergoing isolated CABG between June 2005 and June 2008 at the Tongji Hospital were retrospectively analyzed. Elapsed time between CABG and extubation of more than 8hours was defined as late extubation.

RESULTS

The incidence of late extubation after CABG was 69.23% (288/416). Through univariate and logistic regression analysis, the independent risk factors for late extubation after CABG were older age (odds ratio [OR]=4.804), duration of cardiopulmonary bypass (OR=2.426), perioperative use of intra-aortic balloon pump (OR=1.451), preoperative arterial oxygen partial pressure (OR=.204), and postoperative hemoglobin level (OR=.793).

CONCLUSION

Older age, prolonged cardiopulmonary bypass time, perioperative intra-aortic balloon pump requirement, low preoperative arterial oxygen partial pressure, and low postoperative hemoglobin level were identified as the 5 independent risk factors for late extubation after CABG.

Respiratory physiotherapy and incidence of pulmonary complications in off-pump coronary artery bypass graft surgery: an observational follow-up study

BACKGROUND

Heart surgery is associated with an occurrence of pulmonary complications. The aim of this study was to determine whether pre-surgery respiratory physiotherapy reduces the incidence of post-surgery pulmonary complications.

METHODS

Observational study of 263 patients submitted to off-pump coronary artery bypass grafting (CABG) surgery at the A Coruña University Hospital (Spain). 159 (60.5%) patients received preoperative physiotherapy. The fact that patients received preoperative physiotherapy or not was related to whether they were admitted to the cardiac surgery unit or to an alternative unit due to a lack of beds. A physiotherapist provided a daily session involving incentive spirometry, deep breathing exercises, coughing and early ambulation. A logistic regression analysis was carried out in order to identify variables associated with pulmonary complications.

RESULTS

Both groups of patients (those that received physiotherapy and those that did not) were similar in age, sex, body mass index, creatinine, ejection fraction, number of affected vessels, O2 basal saturation, prevalence of diabetes, dyslipidemia, exposure to tobacco, age at smoking initiation, number of cigarettes/day and number of years as a smoker. The most frequent postoperative complications were hypoventilation (90.7%), pleural effusion (47.5%) and atelectasis (24.7%). In the univariate analysis, prophylactic physiotherapy was associated with a lower incidence of atelectasis (17% compared to 36%, p = 0.01). After taking into account age, sex, ejection fraction and whether the patients received physiotherapy or not, we observed that receiving physiotherapy is the variable with an independent effect on predicting atelectasis.

CONCLUSION

Preoperative respiratory physiotherapy is related to a lower incidence of atelectasis.

Pulmonary protection during cardiac surgery: systematic literature review

Ischemia-reperfusion injury occurs during heart surgery in which cardiopulmonary bypass is used. Current knowledge of the factors contributing to postoperative pulmonary dysfunction and the measures to avoid it are reviewed.

Intrathecal morphine plus general anesthesia in cardiac surgery: effects on pulmonary function, postoperative analgesia, and plasma morphine concentration

OBJECTIVES

To evaluate the effects of intrathecal morphine on pulmonary function, analgesia, and morphine plasma concentrations after cardiac surgery.

INTRODUCTION

Lung dysfunction increases morbidity and mortality after cardiac surgery. Regional analgesia may improve pulmonary outcomes by reducing pain, but the occurrence of this benefit remains controversial.

METHODS

Forty-two patients were randomized for general anesthesia (control group n=22) or 400 microg of intrathecal morphine followed by general anesthesia (morphine group n=20). Postoperative analgesia was accomplished with an intravenous, patient-controlled morphine pump. Blood gas measurements, forced vital capacity (FVC), forced expiratory volume (FEV), and FVC/FEV ratio were obtained preoperatively, as well as on the first and second postoperative days. Pain at rest, profound inspiration, amount of coughing, morphine solicitation, consumption, and plasma morphine concentration were evaluated for 36 hours postoperatively. Statistical analyses were performed using the repeated measures ANOVA or Mann-Whiney tests (*p<0.05).

RESULTS

Both groups experienced reduced FVC postoperatively (3.24 L to 1.38 L in control group; 2.72 L to 1.18 L in morphine group), with no significant decreases observed between groups. The two groups also exhibited similar results for FEV1 (p=0.085), FEV1/FVC (p=0.68) and PaO2/FiO2 ratio (p=0.08). The morphine group reported less pain intensity (evaluated using a visual numeric scale), especially when coughing (18 hours postoperatively: control group= 4.73 and morphine group= 1.80, p=0.001). Cumulative morphine consumption was reduced after 18 hours in the morphine group (control group= 20.14 and morphine group= 14.20 mg, p=0.037). The plasma morphine concentration was also reduced in the morphine group 24 hours after surgery (control group= 15.87 ng.mL-1 and morphine group= 4.08 ng.mL-1, p=0.029).

CONCLUSIONS

Intrathecal morphine administration did not significantly alter pulmonary function; however, it improved patient analgesia and reduced morphine consumption and morphine plasma concentration.

Coronary artery bypass graft and/or valvular operations following prior pneumonectomy: report of four new patients and review of the literature

BACKGROUND

The reported experience is sparse for patients with prior pneumonectomy who are undergoing surgery for ischemic or valvular heart disease. Such surgery poses special technical challenges. To expand the experience with this challenging clinical intervention, we reviewed the reported patients with prior pneumonectomy who were undergoing cardiac surgery as well as the experience at the Cleveland Clinic.

METHODS

A MEDLINE search of the literature for articles published in the English language from 1966 to August 2006 was conducted using the search terms "pneumonectomy" and "cardiac surgery." We included all available individually described patients and also reviewed the Cardiovascular Information Registry at the Cleveland Clinic from 1972 to 2006.

RESULTS

A total of 19 individually described patients in 13 reports were available, 15 of which had previously been reported and 4 that were newly reported from our institution (1 of whom had undergone two operations separated by 8 years). Of the 20 operations performed in these 19 patients, coronary artery bypass grafting (CABG) alone was performed in 15 patients (75%), valve replacement or repair was performed in 4 patients (20%), and CABG with both aortic valve replacement and mitral valve repair was performed in 1 patient (5%). Most patients (13; 68%) had undergone left pneumonectomy. For these 19 patients, the postoperative mortality rate was 16%. Postoperative complications followed 10 of the operations (50%).

CONCLUSIONS

Although complications and postoperative deaths occurred more frequently than in other high-risk patient groups (eg, those with COPD undergoing cardiac surgery), this experience suggests that cardiac surgery can be undertaken with a reasonable likelihood of a favorable outcome in this challenging population, justifying the approach in appropriately selected and counseled patients.

Mechanisms of pulmonary dysfunction after on-pump and off-pump cardiac surgery: a prospective cohort study

BACKGROUND

Pulmonary dysfunction following cardiac surgery is believed to be caused, at least in part, by a lung vascular injury and/or atelectasis following cardiopulmonary bypass (CPB) perfusion and collapse of non-ventilated lungs.

METHODS

To test this hypothesis, we studied the postoperative pulmonary leak index (PLI) for 67Ga-transferrin and (transpulmonary) extravascular lung water (EVLW) in consecutive patients undergoing on-pump (n = 31) and off-pump (n = 8) cardiac surgery. We also studied transfusion history, radiographs, ventilatory and gas exchange variables.

RESULTS

The postoperative PLI and EVLW were elevated above normal in 42 and 29% after on-pump surgery and 63 and 37% after off-pump surgery, respectively (ns). Transfusion of red blood cell (RBC) concentrates, PLI, EVLW, occurrence of atelectasis, ventilatory variables and duration of mechanical ventilation did not differ between groups, whereas patients with atelectasis had higher venous admixture and airway pressures than patients without atelectasis (P = 0.037 and 0.049). The PLI related to number of RBC concentrates infused (P = 0.025).

CONCLUSION

The lung vascular injury in about half of patients after cardiac surgery is not caused by CPB perfusion but by trauma necessitating RBC transfusion, so that off-pump surgery may not afford a benefit in this respect. However, atelectasis rather than lung vascular injury is a major determinant of postoperative pulmonary dysfunction, irrespective of CPB perfusion.

Effects of alveolar recruitment on arterial oxygenation in patients after cardiac surgery: a prospective, randomized, controlled clinical trial

OBJECTIVE

Pulmonary atelectasis and hypoxemia remain considerable problems after cardiac surgery. The objective of this study was to determine the efficacy of consecutive vital capacity maneuvers (C-VCMs) to improve oxygenation in patients after cardiac surgery.

STUDY DESIGN

Randomized, controlled clinical trial.

SETTING

Tertiary referral teaching center.

PARTICIPANTS

Ninety-five patients requiring elective cardiac surgery with cardiopulmonary bypass (CPB).

INTERVENTION

Patients were randomly allocated to either C-VCM or control groups. In the C-VCM group, lung inflation at pressure of 35 cmH(2)O was sustained for 15 seconds before separation from CPB and at 30 cmH(2)O for 5 seconds after admission to the intensive care unit (ICU).

MEASUREMENTS AND MAIN RESULTS

The primary outcome was the ratio of arterial oxygen tension to inspired oxygen fraction measured at the following predetermined time intervals: after induction of anesthesia, 15 minutes after separation from CPB, after admission to the ICU, after 3 hours of positive-pressure ventilation, after extubation, and before ICU discharge. C-VCM resulted in better arterial oxygenation extending from the immediate postoperative period to approximately 24 hours after surgery at the time of ICU discharge. There were no significant adverse events related to C-VCM application.

CONCLUSION

C-VCM is an effective method to reduce hypoxemia associated with the formation of atelectasis after cardiac surgery with CPB.