Hariri, Firman
(2015)
A retrospective study of risk factors for prolonged mechanical ventilation after coronary artery bypass grafting (CABG) surgery in Hospital Universiti Sains Malaysia Kubang Kerian Kelantan.
Masters thesis, Universiti Sains Malaysia.
Abstract
INTRODUCTION
Prolonged mechanical ventilation after CABG surgery increases airway and lung
trauma ultimately increases hospitalization costs. It is well documented that the main
clinical advantages of early extubation are reduced likelihood the adverse effects of
positive pressure ventilation and minimized of associated patient discomfort, a potential
decrease in infection and early ambulation. Many has attempted in promoting early
extubation as a mean to reducing intensive care and hospitalization costs. A few models
have been developed aim to identify patients at risks of PMV. Some studies attempted
to compare those prediction models developed in the ICU.
The main objective of this study is to identify patient characteristics and operative
variables that predict PMV in patients undergoing coronary artery bypass grafting
(CABG). The record of patients who underwent CABG from January 2009 to December
2013 will be examined retrospectively. These patients will be divided into normal and
prolonged mechanical ventilation (PMV) groups. Putative factors affecting the durationof intubation will be included in univariate analysis and subsequently run into logistic
regression model to determine the risk factors associated with PMV.
There were numerous studies that had successfully predicted the risks and established a
risk models. We attempt to study those putative characteristics and variables in a
relatively small cardiothoracic unit whereby patients population were more homogenous
and operated by a single surgeon at Hospital Universiti Sains Malaysia (HUSM) and
compare previously considered risk factors.
METHODOLOGY
It is a retrospective cohort analysis of patient’s case notes in Cardiothoracic Surgery
Unit of Hospital University Sains Malaysia, Kubang Kerian Kelantan. All patients who
had undergone elective isolated CABG between January 2009 and December 2013 are
traced. A computer generated list will be obtained from medical record office. The cases
are identified according to T-codes of the international classification of disease-Tenth
revision (ICD-10). Sampling frame is obtained and all patients fulfilling the inclusion
and exclusion criteria were recruited. Selected perioperative characteristics data will be
collected by reviewing traced medical records. Keywords used when retrieving records
is coronary artery bypass grafting or CABG. Statistical analysis was done using SPSS
software version 22.0.
RESULTS
There were 140 patients enrolled, only twenty four patients required prolonged
mechanical ventilation (PMV) of more than 24 hours. This made the incidence of
17.1%. Male gender contributed to the majority of the PMV group 91.7%. This
percentage however did not reflect the true gender distribution as the number of female
population in the study was only 19 and only 2 fall into the PMV group. Perioperative
univariate analysis showed that renal dysfunction (20.8% versus 3.4%; p = 0.05),
NYHA class IV (37.5% versus 6.9%; p < 0.01), recent MI (58.3% versus 12.9%; p <
0.01), LVEF < 30% (16.7% versus 4.3%; p = 0.037), preoperative PaCO2 (35.0 versus
39.2; p = 0.113), cardiopulmonary bypass time (136 minute versus 126 minute; p =
0.175), intraoperative blood transfusion (925 ml versus 831 ml; p = 0.24), post operative
cardiac arrhythmias (37.5% versus 12.1%; p = 0.004), post operative acute renal failure
(33.3% versus 1.7%; p < 0.001) and post operative hemorrhage (58% versus 4.3%; p <
0.001) were significant. In multiple logistic regression analysis, study demonstrates
renal dysfunction (OR = 12.90; 95% CI 1.33-124.99), advance NYHA class IV (OR =
7.10; 95% CI 1.33-37.93), recent MI (OR = 8.12; 95% CI 1.81-36.38) and postoperative
hemorrhage (OR = 25.1; 95% CI 4.73-132.76) were found to be independent risk
factors associated with PMV after CABG surgery. The study also demonstrates
significant higher length of hospital stay in PMV group. For 1 day additional hospital
stay, it increases the risk of PMV by 1.18 times (95% CI 1.05-1.31) when adjusted to
other factors.
CONCLUSION
Prolonged mechanical ventilation after CABG surgery is associated with the presence of
existing renal dysfunction, NYHA class IV, recent myocardiac infarction and post
operative hemorrhage. Those patients who require prolonged ventilation have
significantly higher hospital stay.
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