in recent decades , interventional procedures in cardiac surgery have developed as widely used techniques of treating valvular dysfunctions and coronary artery diseases . to reduce postoperative complications and increase outcome in patients undergoing cardiac surgery , risk assessment is a vital component in the practice of cardiac surgery.1 , 2 reintubation after cardiac surgery is unusual ; however , it significantly increases postoperative morbidity and mortality risks.3 , 4 reintubation prolongs the duration of mechanical ventilation and intensive care unit ( icu ) bed occupation and is associated with higher in - hospital mortality rates.57 in addition , reintubated patients need more nursing care and financial resources . unfortunately , few studies have been conducted to evaluate the rate of reintubation , factors related to reintubation , and patient outcome . nonetheless , engoren suggested respiratory variables as the main predicting factors of reintubation after cardiac surgery.4 considering the original organ disease , i.e. cardiovascular diseases , in our patient population and the main procedure being performed , i.e. cardiac surgery , we hypothesized that cardiac variables could be significantly considered as the predictors of postoperative reintubation following cardiac surgery . the present study , therefore , aimed at determining the reintubation rate , factors related to postoperative cardiac surgery reintubation , and outcome of adult patients undergoing cardiac surgery . this prospective observational study was conducted in a university hospital on adult patients undergoing cardiac surgical procedures using cardiopulmonary bypass ( cpb ) over a 5-month interval ending in march 2009 . data , including age , gender , new york heart association status ( nyha ) , ejection fraction ( ef ) , smoking ( regular cigarette smoking at least to two months before surgery ) , arterial partial pressure of oxygen ( pao2 ) , arterial partial pressure of carbon dioxide ( paco2 ) , inotropic therapy , presence of an intra - aortic balloon pump ( iabp ) , and comorbidity factors ( diabetes mellitus : fasting blood surgery [ fbs ] > 126 mg / dl or history of diabetes requiring treatment , documented chronic obstructive pulmonary disease [ copd ] , and renal insufficiency [ serum creatinine > 2 mg / dl ] ) , were collected . inclusion criteria consisted of all adult patients who underwent ( elective ) cardiac surgery ( coronary artery bypass grafting [ cabg ] and/or valvular surgery ) . we excluded patients who were intubated before surgery and those who underwent cardiopulmonary resuscitation or were in cardiogenic shock and also emergency operations . we also excluded patients who experienced severe complications in the cardiac catheterization laboratory and were urgently intubated and admitted to the operating room . the definition of  reintubation  in this study was any repeated endotracheal intubation of extubated patients after cardiac surgery due to medical ( cardiovascular , respiratory , neurological , etc . ) causes and complications except the patients who were returned to the operating room for surgical re - exploration . benzodiazepine ( midazolam 0.05 to 0.1 mg / kg ) , opioids ( fentanyl 25  40 g / kg or sufentanil 2.5  4 g / kg ) , and muscle relaxants ( cisatracurium 0.15 mg / kg / iv bolus ) for induction and thiopental 1 midazolam , fentanyl or sufentanil , atracurium or pancuronium , and isoflurane up to 1% were administered . all the operations were performed using cpb at mild to moderate hypothermia ( 28 to 32 c ) . myocardial protection was accomplished with intermittent antegrade or combined antegrade and retrograde saline or blood cardioplegia . the patients were extubated according to the following extubation criteria : respiratory rate = 10  28 / min ; negative inspiratory force > 20 cm h2o ; tidal volume > 5 ml / kg body weight ; pao2 > 60 mm hg with fraction of inspired oxygen ( fio2 ) < 0.4 ; paco2 < 50 mm hg ; hemodynamic stability ; mediastinal and chest tubes drainage < 100 ml / h ; oropharyngeal temperature > 36.5c ; and acceptable chest radiographies.3 postoperative pain was controlled using intravenous morphine or fentanyl and sodium diclofenac suppository . midazolam and haloperidol were also used for controlling sedation and agitation , respectively . during icu stay , respiratory , nephrology , and neurological complications were checked daily by cardiac anesthesiologists . duration of mechanical ventilation was defined as the hours with mechanical ventilation during icu stay . daily postoperative chest radiographies were obtained for evidence of pulmonary complications such as plural effusion , atelectasis , and pneumothorax . cardiovascular status , defined as cardiac rhythm and need to inotropic drugs or iabp , was checked every day . the necessity for inotropic medication administration was defined as a moderate to high doses of one of the inotropic drugs required for hemodynamic stability for more than one hour . postoperative ef was determined using transthoracic echocardiography ( tte ) and compared with preoperative values . bleeding was defined as  200 ml / h or > 1000 ml in twenty - four hours . tamponade was delineated by clinical examination and tte and then confirmed after re - exploration . postoperative renal insufficiency was considered as creatinine concentration > 2 mg / dl or increase in preoperative values > 1 mg / dl . infection was confirmed by positive blood , sputum , urine , plural , or mediastinal fluid cultures and incision discharge . the patients were evaluated regarding preoperative , operative , and postoperative characteristics to determine which would mostly predict reintubation necessity . all preoperative , operative , and outcome data were recorded postoperatively and analyzed using spss statistical package version 15.0 ( spss inc . chicago , il , usa ) . in the re - intubated patients ( n = 26 ) , the kolmogorov - smirnov test was applied to check for normal distribution in the continuous variables and only  ventilation time  and  icu stay time  did not fit normal distribution and were , therefore , removed from the univariate analysis . to compare the continuous variables between the two study groups , the independent samples t - test ; and to compare the categorical variables ; the reintubated group was compared with the non - reintubated group ( n = 946 ) using univariate and multivariate analyses to identify predictors for reintubation . binary logistic regression with a stepwise forward selection procedure was employed to develop a model predictive of reintubation after cardiac surgery . variables that were univariately significant at the 0.10 level were considered for inclusion in the model . a p value < 0.05 was required for the variable to enter and stay in the model . of the 1000 studied patients , 22 patients were not extubated and none of them survived . these 22 patients were excluded from the final analysis . from the 978 patients , who underwent extubation , 32 patients experienced reintubation due to emergent surgical re - exploration or postoperative complications such as respiratory , cardiac , or neurological complications ( table 1 ) . of the 32 reintubated patients , 6 patients were emergently returned to the operating room for surgical re - exploration and reintubated after inducing general anesthesia ; these patients were excluded from the statistical analysis as well . finally 972 patients , who experienced extubation after cardiac surgery , were entered into the statistical analysis : 26 patients who experienced reintubation after extubation in the intensive care unit ( icu ) and 946 patients who were extubated successfully . of the 972 patients analyzed , 624 ( 67% ) were male and 348 ( 33% ) were female . tables 2 , 3 , and 4 present the relationships between all the perioperative variables and reintubation in the reintubated group ( n = 26 ) and the non - reintubated group ( n = 946 ) using univariate analysis . our results revealed that the reintubated patients were significantly older and had lower preoperative ef and pao2 than did the control group ( table 2 ) . in addition , the reintubated patients had significantly longer operating and cpb times , more valvular diseases , and more emergent surgical operations ( table 3 ) . in the postoperative period ( table 4 ) , the reintubated patients also developed arrhythmias , plural effusion , bleeding , neurological complications , renal failure , and infection and had longer mechanical ventilation more significantly . a postoperative ef lower than the preoperative value was more significant in the reintubated patients than in the control group . the reintubated patients also required more inotropic drugs and iabp in the postoperative period and had longer icu stay . the mortality rate in this group of patients was 42.3% ( 11 of 26 ) , while no patients in the control group died during hospital stay . the limited number of the reintubated patients in our study ( n = 26 ) forced us to include the limited variables in the regression model each time separately ; as a result , the patients were entered in the model with respect to their preoperative , operative , and postoperative characteristics separately . the postoperative variables in turn were divided into  respiratory  ,  cardiovascular  , and  other  for inclusion in the regression model separately . in the preoperative variables , age and ef had a p value < 0.10 and were entered in the model and then only ef < 35% was a predictor of reintubation in the icu ( p = 0.014 , or = 3.00 , 95%ci : 1.25  7.21 ) . amongst the operative variables , valvular heart surgery was the predictor of reintubation ( p = 0.043 , or = 1.84 , 95%ci : 1.05  3.96 ) . operation time > 180 minutes showed a clinically important but non - significant p value in predicting reintubation ( p value = 0.090 ; or = 3.48 , 95%ci : 0.81  14.87 ) . in the postoperative respiratory variables , only pleural effusion was a predictor of reintubation ( p value = 0.024 , or = 2.93 , 95%ci : 1.15  7.45 ) . of the postoperative cardiac variables , inotropic drug usage did not qualify in the stepwise forward selection ( p value = 0.079 ) , while arrhythmia ( p = 0.006 , or = 3.84 , 95%ci : 1.47  10.03 ) , postoperative ef reduction ( p = 0.001 , or = 11.10 , 95%ci : 3.88  31.79 ) , and iabp use ( p = 0.019 , or = 4.20 , 95%ci : 1.26  14.00 ) were the predictors of reintubation . in the other postoperative variables , bleeding did not qualify in the stepwise forward selection ( p value = 0.208 ) , but neurological complications ( p = 0.049 , or = 2.93 , 95%ci : 1.01  15.63 ) , nephrological complications ( p value = 0.038 , or = 7.47 , 95%ci : 1.12  50.10 ) , and infectious complications ( p value = 0.001 , or = 19.10 , 95%ci : 3.46  27.71 ) were the predictors of reintubation in the icu . in this prospective observational study , we compared reintubated patients with those not reintubated after cardiac surgery . the reintubation rate after cardiac surgery was 2.6% , which was similar to that reported by numerous earlier reports.4 , 8 the incidence of reintubation in previous studies7 , 911 on patients undergoing cardiac surgery was from 1.1% to 6.6% . in fact , the improvement in patients medical care within recent years has decreased the rate of post - cardiac surgery reintubation . in a study , habib et al.,9 found a 2.8 and 3.5% reintubation rate in two groups of patients with early and late extubation time after cardiac surgery , respectively . also , engoren et al.,4 in another study conducted on adult patients reported a 4.2% reintubation rate after cardiac surgery . moreover , they noted that the reintubation rate was higher in patients with co - morbid conditions related to cardiac surgery . cohen et al.,13 concluded that the presence of copd in patients increased the reintubation rate up to 13.5% after cardiac surgery . lauruschkat et al.,10 found that the incidence rates of reintubation amongst diabetic and non - diabetic patients were 4.5% and 1.8% , respectively . using univariate analysis , we found that the patients with advanced age and lower preoperative ef and pao2 had higher reintubation rates . however , after controlling the effect of age , the pao2 value was not a strong marker for predicting reintubation . whereas some previous studies reported copd as a risk factor for reintubation,4 , 13 we found no strong correlation between copd and smoking and reintubation . similarly , spivack14 and branca15 found that copd was not a predictor of respiratory complications , including postoperative respiratory ventilation time . in the present study , in comparison with the control group , the reintubated patients had a high incidence rate of preoperative renal failure but there was no statistically significant difference between the two groups . in contrast , several previous studies have reported a significant correlation between preoperative renal failure and reintubation rate or duration of postoperative mechanical ventilation.4 , 16 in our univariate analysis , valvular surgery or cabg plus valvular surgery , urgency of surgery , longer operation time , and cpb were the risk factors for reintubation . similarly , in some previous reports , these variables were associated with higher reintubation rates and longer mechanical ventilation times.4 , 15 all these factors are probably dependent on one another and reflect patients with poorer conditions and more complicated operations . in the present study , arrhythmia , plural effusion , inotropic drugs and iabp requirement , lower postoperative ef in comparison with preoperative values , and longer mechanical ventilation significantly correlated with reintubation rates and complicated cardiac surgery . in our study , however , in numerous studies fluid balance has been reported to be associated with prolonged mechanical ventilation and reintubation rate.4 , 16 this discrepancy may reflect the different description of positive fluid balance in our study ( we proposed positive balance > 1000 ml within the first twenty - four hours as positive fluid balance ) . we found that the pre- and postoperative ef , surgery on heart valve , arrhythmia , and postoperative requirement of iabp and inotropic drugs were the predictors of reintubation . nevertheless in a previous study by engoren,4 three predictors related to the reintubation rate were copd , respiratory rate , and lower vital capacity . surprisingly the fact that there was a limited number of copd patients in our study ( despite the presence of a large number of smoking patients in our study population in contrast to previous reports ) may be due to the exclusion of severe copd cases by cardiologists during preoperative medical examinations . fuster et al.17 showed that the severity of copd but not copd itself could be an important factor in the prognosis of coronary artery bypass grafting . nineteen ( 73% ) patients were reintubated within a twenty - four hour period after extubation ; this appears to be in consequence of the patients poor primary general condition . these findings are in line with the higher percentage of patients with valvular disease in the present study . moreover , neurological complications , renal failure , infection , and longer icu stay were associated with the reintubation rate in our study . similar to our study , several investigations16 , 18 have defined reintubation as a significant factor increasing postoperative complications and prolonged icu and hospital stay . in our survey , 11 ( 42.3% ) of the reintubated patients died ( 10 cases due to cardiac and 1 patient due to respiratory complications ) , which was much higher than the figure in an earlier report ( 9.8%).4 in this respect , murthy et al.19 showed that hemodynamic status was the main factor for predicting respiratory complications . also , wahl2 described that patients with respiratory failure caused by organ dysfunction ( e.g. cardiac pump failure or stroke ) were more prone to reintubation than were patients with initial respiratory failure ( e.g. pneumonia and copd deterioration ) . in another study , spivack et al.14 suggested that complications of the cardiovascular system and other organs such as the brain were important restricting factors for postoperative recovery of the respiratory system . the limitation of the present study was its relatively small sample size inasmuch as there were only 26 cases of reintubation in our 1000 study patients . the fact that this was a uni - center study and not a multi - center study also diminishes the generalizability of our results . in summary , the present study confirms that reintubation after cardiac surgery is a marker for morbid postoperative period . we found that reintubated patients were more prone to having complications , longer icu stay , and higher in - hospital mortality rates . we also demonstrated that cardiac variables have a significant role in reintubation and mortality rate prediction . consequently , patients undergoing cardiac surgery with reduced cardiac reserve and hemodynamic instability are at risk of reintubation .
background : reintubation in patients after cardiac surgery is associated with undesirable consequences . 
 the purpose of the present study was to identify variables that could predict reintubation necessity in this group of patients.methods:we performed a prospective study in 1000 consecutive adult patients undergoing cardiac surgery with cardiopulmonary bypass . 
 the patients who required reintubation after extubation were compared with patients not requiring reintubation regarding demographic and preoperative clinical variables , including postoperative complications and in - hospital mortality.results:postoperatively , 26 ( 2.6% ) of the 1000 patients studied required reintubation due to respiratory , cardiac , or neurological reasons . 
 advanced age and mainly cardiac variables were determined as univariate intra- and postoperative predictors of reintubation ( all p values < 0.05 ) . 
 multiple logistic regression analysis revealed lower preoperative ( p = 0.014 ; or = 3.00 , 95%ci : 1.25  7.21 ) , and postoperative ejection fraction ( p = 0.001 ; or = 11.10 , 95%ci : 3.88  31.79 ) , valvular disease ( p = 0.043 ; or = 1.84 , 95%ci : 1.05  3.96 ) , arrhythmia ( p = 0.006 ; or = 3.84 , 95%ci : 1.47  10.03 ) , and postoperative intra - aortic balloon pump requirement ( p = 0.019 ; or = 4.20 , 95%ci : 1.26  14.00 ) as the independent predictors of reintubation.conclusions:these findings reveal that cardiac variables are more common and significant predictors of reintubation after cardiac surgery in adult patients than are respiratory variables . 
 the incidence of this complication , reintubation , is low , although it could result in significant postoperative morbidity and mortality .