93J Contemp Med Sci | Vol. 9, No. 2, March-April 2023: 93–100 Original Investigation of the Frequency and Risk Factors of Pulmonary Complications Following Cardiac Surgery in the Hospital Mahdieh Sharifzadeh Kermani1, Naeimeh Naeimi Bafghi2, Neda Naeimi Bafghi2, Shirin Salajegheh1*, Jafar Salehi3, Reza Nakhaei Zadeh4, Mohammad Javad Javid1 1Clinical Research Development Unit, Shafa Hospital, Kerman University of Medical Sciences, Kerman, Iran. 2Clinical Research Development Unit, Shahid Bahonar Hospital, Kerman University of Medical Sciences, Kerman, Iran. 3Department of Anesthesiology, School of Medicine, Kerman University of Medical Sciences, Kerman, Iran. 4Department of Cardiac Surgery, School of Medicine, Kerman University of Medical Sciences, Kerman, Iran. *Correspondence to: Shirin Salagegheh (E-mail: drshirinsalajegheh@aol.com) (Submitted: 10 January 2023 – Revised version received: 21 February 2023 – Accepted: 15 March 2023 – Published online: 26 April 2023) Abstract Objectives: The purpose of this study was to determine the frequency of pulmonary complications after heart surgery and to assess the pre-operative, intra-operative and post-operative risk factors. Methods: This was a descriptive and analytical study that was conducted on 244 patients who underwent various cardiac surgeries from December 2021 to May 2022 in Shefa Kerman Hospital. This descriptive/analytical study on patients undergoing heart surgery at Shafa Hospital, Kerman, Iran, from December 2021 to May 2022. Pulmonary complications included atelectasis pneumonia, pleural effusion, long-term mechanical ventilation, and respiratory failure. The pre-operative, intra-operative and post-operative risk factors were investigated in the present study. SPSS software was used to analyze the data. Logistic regression analysis was employed to determine the relationship between risk factors and the incidence of lung complications. Results: In the present study, 55 patients (22.5%) had pulmonary complications, followed by prolonged mechanical ventilation (13.1%), pneumonia (11.5%), respiratory failure (4.1%), pleural effusion (11.1%) and atelectasis (6.1%). Pulmonary complications after heart surgery were associated with days of ICU stay, post-operative stroke, post-operative acute kidney injury, emergency surgery, FFP injection, high drainage rate, and mitral valve replacement surgery (all P < 0.001). 4% of patients died after surgery, which was statistically related to pulmonary complications (P < 0.0001). The results of multivariable logistic regression test showed that FFP injection, type of heart surgery, hypertension, ICU stay days are capable of predicting pulmonary complications after heart surgery. Conclusion: Mortality was found to be higher in patients with pulmonary complications. Based on the results of the regression analysis, FFP injection, type of surgery, history of hypertension and length of ICU stay were independent risk factors of pulmonary complications. Key words: Pulmonary complications, cardiovascular surgery, risk factors, Fresh frozen palsma ISSN 2413-0516 Introduction Cardiac surgery is a high-risk intervention that requires special- ized teams to manage patients in the pre- and post-operative care. Pulmonary complications include pneumonia with mechanical ventilation for more than 24 hours, respiratory failure, pleural effusion, atelectasis, pneumothorax, bronchospasm and aspira- tion pneumonitis, acute respiratory distress syndrome, and pul- monary embolism, which increases the length of hospital stay and treatment costs.1 Heart surgery is usually performed by cardiopulmonary bypass. In this technique, the pumping action of the heart and the gas exchange of the lungs are temporarily replaced by a special mechanical device called an oxygenator pump, which is connected to the vascular system. Cardiopulmonary bypass exposes the blood to artificial substances that lead to the pro- duction and secretion of toxins and the activation of the vas- cular reaction. In addition, the activation of neutrophils and their migration to the pulmonary circulation causes deep endothelial, epithelial, and interstitial lung damage, which is associated with increased capillary permeability, decreased lung capacity, and gas exchange disorders.2,3 Abnormalities in gas exchange and changes in lung mechanical function cause pulmonary complications after heart surgery. In recent studies, changes in muscle and chest wall function due to median ster- notomy, systemic inflammatory response syndrome with car- diopulmonary bypass, phrenic nerve injury due to cold saline injection in the pericardial cavity during cardiac arrest, and dilatation associated alveolar edema, and an increase in left ventricular pressure in the pulmonary vessels has been stated as the main causes of this complication.4,5 The reported frequency of pulmonary complications after cardiac surgery varies from 6 to 70% depending on the criteria used to define pulmonary complications.6 The incidence of pulmonary complications in major surgeries varies from 1 to 23%.7 Identifying the risk factors of susceptible patients is helpful in preventing and eliminating complications. Previous studies reported a combination of preoperative and postoper- ative risk factors. Despite many advances in intraoperative care, postoperative pulmonary complications remain the main cause of disability and death after cardiac surgery in adults.8,9 Very few studies have focused on intra- and post-opera- tive risk factors responsible for pulmonary complications in patients undergoing cardiac surgery using cardiopulmonary bypass.10,11 Ventilation with a flow volume of 4–6 cc/kg during sur- gery was associated with a decrease in pulmonary complica- tions.12 It has been reported that age over 60 years, prolongation of surgery time, preoperative pulmonary blood pressure and intraoperative phrenic nerve damage were risk factors for pul- monary complications.6 Determining the factors affecting the rate of pulmonary complications can be beneficial in order to reduce these risk factors and timely treatment of more common pulmonary complications in patients after heart surgery. If risk factors are found, comprehensive and complete treatment of these factors mailto:drshirinsalajegheh@aol.com 94 J Contemp Med Sci | Vol. 9, No. 2, March-April 2023: 93–100 Investigation of the Frequency and Risk Factors of Pulmonary Complications Following Cardiac Surgery Original M.S. Kermani et al. can be effective in improving the clinical course of patients who underwent heart surgery. In Iran, there is a lack of studies on pulmonary complica- tions after heart surgery.13,14 Considering the large number of heart surgeries in Iran and the high global prevalence of post- operative pulmonary complications, it is necessary to deter- mine the prevalence of this complication and its related factors in Iran. The current study aimed to investigate the frequency and risk factors of pulmonary complications following cardiac surgery in Shafa Hospital between 2021 and 2022. Materials and Methods This is a descriptive/analytical cross-sectional study approved by the ethics committee of Kerman University of Medical Sciences (IR.KMU.AH.REC.1401.104). The research population included all patients who under- went heart surgery (coronary artery grafting, heart valve replacement, atrial septum repair, and ventricular septal defect repair) at Shafa Hospital, Kerman, Iran, from December 2021 to May 2022. The research population included all patients who under- went heart surgery (coronary artery grafting, heart valve replacement, atrial septum repair, and ventricular septal defect repair) at Shafa Kerman Hospital from December 2021 to May 2022. Patients who had surgery for congenital heart disease and incomplete medical records were excluded from the study. The data was extracted from the patient files through a researcher-made form including demographic information and medical information. Collected data includes the variables of age, sex, smoking, opioid use, body mass index, ejection fraction, type of surgery, duration of surgery, type of pulmonary complication, use of cardiopulmonary pump during surgery. Surgery, duration of cardiopulmonary pump, duration of mechanical ventilation, acute kidney injury after surgery, hemoglobin level before sur- gery, co-morbidity (diabetes, hypertension), duration of hos- pitalization in intensive care unit (ICU), transfusion of blood or blood products, type of surgical urgency, postoperative drainage and mortality. Pulmonary complications investigated included: pleural effusion, which was investigated and recorded by lung ultra- sound and x-ray), pneumonia (fever, purulent sputum, test findings, lung x-ray and confirmed by infectious consulta- tion), atelectasis (confirmed by lung x-ray and ultrasound), prolonged mechanical ventilation (more than 24 hours) and acute respiratory distress syndrome (ARDS). Statistical Analysis Descriptive data were presented using mean, standard devia- tion, frequency and percentage in the form of tables and graphs. The Kolmogorov Smirnov test was used to check the normality of the data. T-test was used to compare the mean of two groups for normal data. Mann Whitney U test for non-normally distributed data and Chi square test was used to analyze qualitative data. Logistic regression analysis (Back- ward: LR) was used to investigate the simultaneous effect of demographic and medical variables with postoperative pul- monary complications. The first group was considered as the reference group. SPSS software version 24 was used for data analysis. A significance level of less than 0.05 was considered. Results 244 patients with a mean age of 59 ± 12 (15–82 years) partici- pated in this study, consisting of 167 (68%) men and 77 (32%) women. The average height and weight of the patients were 168 ± 9 and 68 ± 13, respectively. The average BMI in these people was 24 ± 4 (range 14–37). 50% of patients used opium and 10% smoked. Of these patients, 36% had diabetes, 68% had hypertension, and 5% had chronic kidney disease. The mean preoperative hemoglobin in the patients was 14 ± 2. The average ejection fraction in patients was 44 ± 10. The average ejection fraction in patients before surgery was determined to be 44 ± 10. 6% of patients underwent emergency surgery and 88% underwent elective surgery. The average time of surgery was 4 ± 0.8 hours (range 2–8 hours). 49% of patients used cardio- pulmonary pump with an average duration of 37 ± 32 minutes. According to the type of surgery, 87% of patients under- went open heart surgery, followed by mitral valve replace- ment (8%), aortic valve replacement (6%), septal defect surgery (3%), and other surgeries (3%). After surgery, 55 patients (22.5%) had pulmonary complications, followed by prolonged mechanical ventilation (13.1%), pneumonia (11.5%), respiratory failure (4.1%), pleural effusion (11.1%) and atelectasis (6.1%). The duration of the intensive care unit (ICU) satay after the operation was 5 ± 3 days. The average duration of mechan- ical ventilation in patients was also determined to be 22 ± 31 (range 4.5–264 hours) hours. During or after FFP operation, 17% of PLT and 51% of P.C were injected for 20% of patients. The amount of drainage after surgery was found to be less than one liter for 85% of patients and more than one liter for 15%. 2.5% of patients had a stroke after surgery and 17.6% had acute kidney failure. Finally, 4% of patients died after surgery. No significant difference was found in terms of the gender in two groups with pulmonary complications after cardiac surgery and without pulmonary complications after cardiac surgery. No significant difference was observed between on-pump and off-pump patients in two groups with pulmonary compli- cations after heart surgery and without pulmonary complica- tions after heart surgery. A significant difference was found in terms of the type of urgency in two groups after heart surgery. Patients who under- went emergency surgery had more pulmonary complications after heart surgery. A statistically significant difference was also revealed in terms of drainage in two groups after heart surgery. Patients who had more than one liter of drainage on the first day had more pulmonary complications after heart surgery. A significant difference was observed in terms of post op CVA in two groups after heart surgery. All patients who had a stroke had pulmonary complications after heart surgery. A statistically significant difference was found in terms of death in patients in two groups after heart surgery, where patients who died showed more pulmonary complications after heart surgery. A significant difference was also seen in terms of acute kidney injury in patients of two groups after heart surgery. The frequency of pulmonary complications was higher in patients with acute kidney injury. 95J Contemp Med Sci | Vol. 9, No. 2, March-April 2023: 93–100 M.S. Kermani et al. Original Investigation of the Frequency and Risk Factors of Pulmonary Complications Following Cardiac Surgery Table 1. Descriptive statistics N Minimum Maximum Mean Std. deviation Age in years 243 15 82 58.75 11.699 Weight in kg 244 2.00 120.00 68.3975 13.26509 Height in cm 244 147.00 198.00 168.1844 8.55885 BMI 205 14.03 36.63 24.0432 3.92621 Ejection fraction in percent 238 20.00 65.00 44.0126 10.19700 Surgery duration in minutes 244 140.00 465.00 251.6189 47.83311 Pump_time in minutes 244 .00 199.00 32.1352 36.59693 Days of ICU admission 244 1.00 24.00 4.9508 3.22631 Mechanical ventilation hours 244 4.50 264.00 22.0266 30.58241 Pre op Hb 244 9.1 22.7 14.201 2.1269 Valid N (listwise) 199 No significant difference was observed in patients of two groups in terms of drug use, smoking, blood pressure, diabetes and chronic kidney disease. A significant difference was observed in terms of mitral valve replacement in the two groups of patients after heart sur- gery. The frequency of pulmonary complications was higher in patients who had mitral valve replacement. A significant difference was observed in terms of other surgeries in patients of two groups. The frequency of pulmo- nary complications was higher in patients who had other surgeries. In terms of FFP injection, a significant difference was observed in two groups. The frequency of pulmonary compli- cations was higher in patients who received FFP injection. There was no statistically significant difference in the mean age of patients in the two groups (P = 0.374) No statistically significant difference was found in the average duration of surgery in the two groups of patients (P = 0.735) There was a statistically significant difference in the average days of the ICU stay in the two groups of patients (P < 0.0001). The average days of ICU stay was found to be higher in the group of patients with pulmonary complications after heart surgery (P < 0.0001). There was no statistically significant difference between the two groups of patients in the mean preoperative hemo- globin (P = 0.603). The average time of being on the pump in the group of patients with pulmonary complications was higher than the patients without pulmonary complications, but this difference was not found to be statistically significant (P = 0.101). The results of multivariable logistic regression test demonstrated that FFP injection, type of heart surgery, blood pressure, and number of days of the ICU stay can be capable of predicting pulmonary complications after heart surgery. People who had aortic valve replacement surgery are 91.7 times more likely to have pulmonary complications after heart surgery. People who had mitral valve replacement surgery are 73 times more likely to have pulmonary complications after heart surgery. Patients who had septal defect surgery are 128 times more likely to have pulmonary complications after heart surgery. Patients with open heart surgery have 36.8 times more pulmonary complications after heart surgery. Every day ICU stay was capable of increasing the chance of pulmonary com- plications by 1.72 times. People who had high blood pressure are 4.6 times more likely to have pulmonary complications after heart surgery. Patients who received FFP injections were 4.6 times more likely to have pulmonary complications after heart surgery. Discussion The present study was conducted with the aim of investigating the frequency and risk factors of pulmonary complications following heart surgery in Shafa Hospital from December 2021 to May 2022. 244 patients who underwent heart surgery during a period of 6 months were included in the study. In our study, there was no relationship between pulmonary compli- cations and demographic characteristics, including average age, sex, and body mass index. The results of our study showed an incidence of 22.5% for pulmonary complications after heart surgery. Pulmonary complications after heart surgery were related to type of sur- gery (mitral valve replacement surgery, other heart sur- geries), history of hypertension, prolonged stay in ICU, urgency of heart surgery, post-operative acute kidney injury, post-operative stroke, FFP injection and high drainage rate. Mortality was significantly higher in patients with pulmo- nary complications. Regarding the regression analysis of plasma injection, type of surgery, history of hypertension and length of stay in ICU were independent risk factors for devel- oping pulmonary complications. One of the positive points of our study was the compre- hensive review of pre-operative, intra-operative and post- operative risk factors in order to determine the frequency and risk factors influencing the development of pulmonary com- plications. Regarding the retrospective nature of the study, it was not possible to investigate the thickness of the diaphragm and possible paralysis in pulmonary complications. The most common pulmonary complications in patients were long-term mechanical ventilation (more than 24 hours, 13.1%) and pneumonia (11.5%). Considering that infection is an important factor of morbidity and mortality around 96 J Contemp Med Sci | Vol. 9, No. 2, March-April 2023: 93–100 Investigation of the Frequency and Risk Factors of Pulmonary Complications Following Cardiac Surgery Original M.S. Kermani et al. Table 2. Frequency of pulmonary complications in heart surgery patients according to demographic and clinical characteristics Pulmonary complicationTotal P-valueNo Yes PercentFrequency 0.65512839Frequency68.4167Male Sex 76.6%23.4%Percent 6116Frequency31.677Female 79.2%20.8%Percent 0.5059926Frequency51.2125OffPump 79.2%20.8%Percent 9029Frequency48.8119On 75.6%24.4%Percent P < 0.0001611Frequency5.714EmergencyUrgent type of surgery 35.3%64.7%Percent 18344Frequency88.5216Elective 80.6%19.4%Percent 0.04716542Frequency84.8207Below 1litDrainage 79.7%20.3%Percent 2413Frequency15.237Over 1lit 64.9%35.1%Percent P < 0.000118949Frequency97.5238NoPost op CVA 79.4%20.6%Percent 06Frequency2.56Yes 0.0%100.0%Percent P < 0.000118648Frequency95.9234NoDeath 79.5%20.5%Percent 37Frequency4.110Yes 30.0%70.0%Percent 0.00116437Frequency82.4201NoAcute kidney injury 81.6%18.4%Percent 2518Frequency17.643Yes 58.1%41.9%Percent Table 3. Frequency of pulmonary complications in heart surgery patients based on underlying diseases, type of heart surgery and transfusion of blood and blood products Total Pulmonary complication Frequency Percent No Yes Underlying diseases Opioid addiction No 123 50.4 Frequency 101 22 Percent 82.1% 17.9% Yes 121 49.6 Frequency 88 33 Percent 72.7% 27.3% Smoking No 219 89.8 Frequency 170 49 Percent 77.6% 22.4% Yes 24 9.8 Frequency 19 5 Percent 79.2% 20.8% Unknown .4 .4 Frequency (continued) 97J Contemp Med Sci | Vol. 9, No. 2, March-April 2023: 93–100 M.S. Kermani et al. Original Investigation of the Frequency and Risk Factors of Pulmonary Complications Following Cardiac Surgery Table 3. Frequency of pulmonary complications in heart surgery patients based on underlying diseases, type of heart surgery and transfusion of blood and blood products—Continued Total Pulmonary complication Frequency Percent No Yes Diabetes mellitus No 157 64.3 Percent 125 32 Frequency 79.6% 20.4% Yes 87 35.7 Percent 64 23 Frequency 73.6% 26.4% Hypertension No 79 32.4 Percent 65 14 Frequency 82.3% 17.7% Yes 165 67.6 Percent 124 41 Frequency 75.2% 24.8% Chronic kidney disease No 230 94.3 Percent 180 50 Frequency 78.3% 21.7% Yes 12 4.9 Percent 7 5 Frequency 58.3% 41.7% Unknown 2 .8 Percent Type of cardiac surgery Aortic valve replacement No 230 94.3 Frequency 180 50 Percent 78.3% 21.7% Yes 14 5.7 Frequency 9 5 Percent 64.3% 35.7% Mitral valve replacement No 225 92.2 Frequency 178 47 Percent 79.1% 20.9% Yes 19 7.8 Frequency 11 8 Percent 57.9% 42.1% septal defect No 236 96.7 Frequency 182 54 Percent 77.1% 22.9% Yes 8 3.3 Frequency 7 1 Percent 87.5% 12.5% Cardiac arterial bypass graft No 32 13.1 Frequency 25 7 Percent 78.1% 21.9% Yes 212 86.9 Frequency 164 48 Percent 77.4% 22.6% other No 237 97.1 Frequency 186 51 Percent 78.5% 21.5% Yes 7 2.8 Frequency 3 4 Percent 42.9% 57.1% Transfusion of blood and blood products FFP No 196 80.3 Frequency 163 33 Percent 83.2% 16.8% Yes 48 19.7 Frequency 26 22 Percent 54.2% 45.8% PLT No 202 82.8 Frequency 159 43 Percent 78.7% 21.3% Yes 42 17.2 Frequency 30 12 Percent 71.4% 28.6% P.C No 120 49.2 Frequency 93 27 Percent 77.5% 22.5% Yes 124 50.8 Frequency 96 28 Percent 77.4% 22.6% 98 J Contemp Med Sci | Vol. 9, No. 2, March-April 2023: 93–100 Investigation of the Frequency and Risk Factors of Pulmonary Complications Following Cardiac Surgery Original M.S. Kermani et al. Table 4 Frequency of pulmonary complications in patients Variables Frequency Percent Pulmonary complication No 189 77.5 Yes 55 22.5 Pneumonia No 216 88.5 Yes 28 11.5 Respiratory failure No 234 95.9 Yes 10 4.1 Pleural effusion No 217 88.9 Yes 27 11.1 Atelectasis No 229 93.9 Yes 15 6.1 Prolonged mechanical ventilation No 212 86.9 Yes 32 13.1 Table 5. Comparison of the mean of quantitative variables in two groups of patients with pulmonary complications and without pulmonary complications after heart surgery Variables Pulmonary complication N Mean Std. deviation Std. error mean P-value Age in years No 189 58.39 11.945 .869 .374 Yes 54 60.00 10.807 1.471 Surgery duration in minutes No 189 251.0582 45.20570 3.28823 .735 Yes 55 253.5455 56.36088 7.59970 Days of ICU admission No 189 4.1111 1.67056 .12152 P < 0.0001 Yes 55 7.8364 5.11629 .68988 Pre op Hb No 189 14.239 2.1108 .1535 .603 Yes 55 14.069 2.1958 .2961 Pump_time in minutes No 189 29.5185 32.98204 2.39909 0.101 Yes 55 41.1273 46.18965 6.22821 surgery, it is necessary to examine and identify patients at risk for faster control and treatment. The occurrence of pulmonary complications in studies has been between 3 and 50% and its occurrence is the result of pre-operative, intra-operative and post-operative risk factors. Older age, genetics, diabetes, obesity, smoking, chronic lung disease, and emergency surgery have been identified as preoperative risk factors in studies. In our study, emergency surgery and hypertension were risk factors, while other comorbidities were not associated with increased risk, prob- ably owing to the smaller sample size. In our study, one of the risk factors affecting the increase of pulmonary complications during surgery was the type of surgery, i.e., non-coronary and heart valve surgeries. In Sadeghi’s study, patients with heart valve surgery had higher complications and mortality because a large number of these patients suffer from obstructive and restrictive lung dis- ease, which may be due to cardiomegaly, pleural effusion, Table 6. The results of multivariate logistic regression B S.E. Exp(B) 95% C.I. for EXP(B) P-value Lower Upper Gender (1) –.815 .793 .443 .094 .304 .304 Age in years –.031 .028 .969 .917 .270 .270 BMI .050 .069 1.052 .918 .466 .466 Aortic valve replacement (1) 4.519 1.504 91.725 4.813 .003 .003 Mitral valve replacement (1) 4.295 1.755 73.337 2.351 .014 .014 Septal defect (1) 4.857 2.061 128.574 2.265 .018 .018 Coronary arterial bypass (1) 3.606 1.660 36.803 1.423 .030 .030 Surgery duration in minutes –.002 .008 .998 .982 .752 .752 Pump (1) –2.136 1.334 .118 .009 .109 .109 Pump_time in minutes .021 .020 1.021 .982 .298 .298 Opioid addiction (1) .923 .518 2.516 .911 .075 .075 Smoking (1) –.010 .951 .990 .153 .991 .991 Diabetes mellitus (1) .429 .610 1.536 .465 .482 .482 Hypertension (1) 1.540 .690 4.665 1.206 .026 .026 (Continued) 99J Contemp Med Sci | Vol. 9, No. 2, March-April 2023: 93–100 M.S. Kermani et al. Original Investigation of the Frequency and Risk Factors of Pulmonary Complications Following Cardiac Surgery Table 6. The results of multivariate logistic regression—Continued B S.E. Exp(B) 95% C.I. for EXP(B) P-value Lower Upper Chronic kidney disease (1) –2.842 2.312 .058 .001 .219 .219 Days of ICU admission .545 .126 1.724 1.346 .000 .000 FFP (1) 1.539 .591 4.658 1.463 .009 .009 PLT (1) –1.676 .797 .187 .039 .036 .036 P.C (1) –.529 .665 .589 .160 .427 .427 Acute kidney injury (1) .041 .781 1.042 .225 .958 .958 Urgent type of surgery (1) –.690 .946 .502 .079 .466 .466 Drainage (1) .290 .762 1.336 .300 .704 .704 Constant –14.449 3.152 .000 .000 .000 peribronchial and pericapillary fibrosis during the period of pulmonary congestion.14 In our study, Fresh frozen plasma injection was an inde- pendent risk factor for pulmonary complications. It was stated by Gupta et al. that intraoperative blood transfusion was sig- nificantly higher in patients with pulmonary complications after surgery.15 While the results of the study by Mathis and his colleagues showed a significant relationship between the transfusions of various blood products and pulmonary com- plications after heart surgery.12 Following the infusion of blood products, especially plasma and platelets, there is a possibility of complications such as transfusion-related acute lung injury (TRALI), transfusion-related circulatory overload (TACO) and increased risk of infection transmission.16,17 Serani et al. also showed that plasma transfusion in sick patients was associated with an increased risk of infections.18 Bochicchio’s study showed an increased risk of ventilator- associated pneumonia in trauma patients with transfusion of blood products.19 According to the results of our study, plasma injection was introduced as a risk factor for causing postoper- ative pulmonary complications. Transfusion of plasma and blood products is recommended to be based on the indication, if necessary. According to Desborough’s review study, the prophylactic administration of Fresh frozen plasma for patients undergoing cardiovascular surgery is not approved in the absence of coagulopathy, and more research is needed for other outcomes including 30-day mortality due to the bias in the studies and their low quality.20 In the present study, acute kidney failure and longer length of ICU stay were associated with increased pulmonary complications, which was consistent with other studies.21 The mortality rate in patients with pulmonary complica- tions was significantly higher, which was similar to other studies.6,22 Pulmonary complications after heart surgery can be pre- vented by teaching the prevention and management of these risk factors to the health department staff and determining specific protocols. 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