Table 3. Post-operative factors associated with post-CABG pleural effusion.

Variable	Pleural effusion drainage group (n=59)	No pleural effusion drainage group (n=350)	P value
Red cell transfusion post-operatively	27 (45.8%)	126 (36.0%)	0.15
Non-red cell blood products transfused post-operatively	17 (28.8%)	57 (16.3%)	0.02*
Drain outputs first 4 hours (mL)	232.47±291.26	214.67±153.73	0.48
Early return to theatre for bleeding	3 (5.1%)	12 (3.4%)	0.46
Duration of time intubated (hours)	29.44±87.49	11.52±14.55	<0.01*
Time to extubation (hours)	29.44±87.5	11.5±14.6	<0.01*
Prolonged ventilation (>24 hours)	9 (15.3%)	19 (5.4%)	<0.01*
Reintubation	6 (10.2%)	13 (3.7%)	0.03*
ICU length of stay (days)	4.87±4.77	4.14±6.95	0.44
Return to ICU	9 (15.3%)	15 (4.3%)	<0.01*
Highest post-operative creatinine (micromol/L)	151.39±173.56	113.48±92.53	0.01*
Lowest post-operative haemoglobin (gram/L)	80.56±12.14	84.80±14.88	0.04*
Pericarditis	6 (10.2%)	29 (8.3%)	0.63
New post-op arrhythmia	28 (57.1% of those without pre-op AF)	111 (34.4% of those without pre-op AF)	<0.01*
New post-op renal failure	5 (8.5%)	6 (1.7%)	<0.01*
Peri-operative myocardial infarct	0 (0.0%)	1 (0.3%)	~1
Post-operative pneumonia	3 (5.1%)	13 (3.7%)	0.71
Deep sternal wound infection	3 (5.1%)	4 (1.1%)	0.07
Pericardial effusion requiring drainage	7 (11.9%)	1 (0.3%)	<0.01*
Maximum post-operative weight gain (kg)	7.58±3.68	5.89±3.30	<0.01*
Mortality	2 (3.4%)	3 (0.9%)	0.15
Length of stay (post-op) (days)	15.25±10.47	8.93±6.77	<0.01*
Readmission	10 (16.9%)	28 (8.0%)	0.03*

*, statistically significant P value <0.05. CABG, coronary artery bypass grafting.