Balancing intubation time with postoperative risk in cardiac surgery patients – a retrospective cohort analysis

Figures & data

Figure 1 Percentages of patients according to the length of intubation after CABG.

Abbreviation: CABG, coronary artery bypass grafting.

Table 1 Study group characteristics and perioperative data for each intubation time cohort

Data	Intubation time
	0–6 hours, n=148 (7.77%)	6.1–9 hours, n=329 (17.28%)	9.1–12 hours, n=511 (26.84%)	12.1–24 hours, n=846 (44.43%)	>24.1 hours, n=70 (3.68%)	P-value
Demographic data
Age [years] (mean ± SD)	61.98±8.49	63.08±7.55	66.00±7.88	68.07±8.01	70.36±8.31	<0.001
BMI [kg/m^2] (mean ± SD)	29.99±4.58	29.05±4.15	28.94±4.42	28.74±4.32	28.46±4.40	0.032
Gender, male, n (%)	132 (89.19)	291 (88.45)	401 (78.47)	618 (73.05)	44 (64.29)	<0.001
Smoking, n (%)	27 (18.24)	67 (20.43)	91 (17.88)	111 (13.18)	15 (21.74)	<0.001
BMI, n (%)
Normal	17 (11.49)	51 (15.50)	88 (17.22)	160 (18.91)	18 (25.71)	NS
Overweight	62 (41.89)	147 (44.68)	230 (45.01)	367 (43.38)	28 (40.00)
Obese	69 (46.62)	131 (39.82)	193 (37.77)	319 (37.71)	24 (34.29)
Admission type, n (%)
Elective	100 (67.57)	225 (68.39)	354 (69.41)	579 (68.44)	46 (65.71)	NS
Accelerated	37 (25.00)	84 (25.53)	123 (24.12)	208 (24.59)	18 (25.71)
Emergency	11 (7.43)	20 (6.08)	33 (6.47)	59 (6.97)	6 (8.57)
Concomitant diseases
Ejection fraction <30%, n (%)	7 (4.73)	21 (6.38)	32 (6.26)	49 (5.79)	11 (15.71)	0.023
NYHA III and IV, n (%)	13 (9.85)	24 (8.33)	48 (10.55)	93 (12.30)	17 (27.42)	<0.001
Diabetes mellitus, n (%)	71 (47.97)	144 (43.77)	236 (46.18)	404 (47.75)	29 (41.43)	NS
Glucose intolerance, n (%)	8 (5.41)	10 (3.04)	15 (2.94)	32 (3.78)	3 (4.29)	NS
Transient ischemic attack, n (%)	2 (1.35)	2 (0.61)	5 (0.98)	12 (1.42)	1 (1.43)	NS
Stroke, n (%)	6 (4.05)	21 (6.38)	34 (6.65)	45 (5.32)	7 (10.00)	NS
Arterial hypertension, n (%)	110 (74.32)	241 (73.25)	379 (74.17)	650 (76.83)	54 (77.14)	NS
Myocardial infarction, n (%)	80 (54.05)	170 (51.6)	256 (50.1)	462 (54.61)	47 (67.14)	NS
PTCA/Stenting, n (%)	48 (32.43)	124 (37.69)	168 (32.88)	267 (31.56)	20 (28.57)	NS
Atrial fibrillation paroxysmal, n (%)	10 (6.76)	18 (5.47)	29 (5.86)	57 (6.74)	6 (8.57)	NS
Atrial fibrillation persistent, n (%)	8 (5.41)	11 (3.34)	16 (3.13)	27 (3.19)	2 (2.86)	NS
Internal carotid artery stenosis, n (%)	7 (4.73)	20 (6.08)	33 (6.46)	73 (8.63)	10 (14.29)	0.048
COPD, n (%)	7 (4.73)	18 (5.47)	28 (5.48)	49 (5.79)	7 (10.00)	NS
Chronic renal failure, n (%)	5 (3.38)	16 (4.86)	31 (6.07)	45 (5.32)	12 (17.14)	<0.001
Acute renal failure, n (%)	0 (0.00)	0 (0.00)	0 (0.00)	0 (0.00)	6 (0.71)	NS
Extracardiac arteriopathy, n (%)	16 (10.81)	43 (13.07)	101 (19.77)	159 (18.79)	20 (28.57)	0.002
Operative risk
EuroScore Logistic 2 [%] (mean ± SD)	1.87±1.99	1.96±1.97	2.15±2.45	2.42±3.08	5.10±8.80	<0.001
Preoperative factors
Ejection fraction [%] (mean ± SD)	46.57±9.67	46.63±10.41	47.07±9.82	47.14±9.95	43.51±11.33	NS
CKMB [U/L] (mean ± SD)	27.95±35.65	23.77±17.72	25.15±24.18	34.03±94.88	82.66±142.61	<0.001
Hemoglobin [mmol/L] (mean ± SD)	8.62±0.99	8.69±0.92	8.48±0.92	8.43±0.94	8.12±1.16	<0.001
Creatinine [mg/dL] (mean ± SD)	1.00±0.74	0.99±0.64	0.97±0.47	1.04±0.79	1.21±0.53	<0.001
GFR [mL/min/1.73 m^2] (mean ± SD)	85.68±19.97	84.26±18.39	81.88±30.79	77.71±31.41	63.83±22.22	<0.001
Intraoperative factors
CPB time [min] (mean ± SD)	53.16±17.29	48.87±13.35	50.37±13.68	50.02±15.94	60.40±37.05	NS
Aortic cross-clamping time [min] (mean ± SD)	31.85±10.52	30.10±10.09	30.45±9.07	29.66±8.78	30.78±15.80	NS
Re-operation, n (%)	5 (3.38)	5 (1.52)	9 (1.76)	45 (5.32)	14 (20)	<0.001
Intraoperative hemofiltration, n (%)	28 (18.92)	40 (12.16)	92 (18.00)	178 (21.04)	34 (48.57)	<0.001
Postoperative factors
CKMB day 1 [U/L] (mean ± SD)	61.01±67.44	54.59±55.28	55.87±58.40	72.57±148.09	188.12±301.22	<0.001
Drainage day 1 [mL] (mean ± SD)	473.82±306.40	461.96±277.51	443.66±317.96	485.93±435.79	697.57±767.97	0.002
Creatinine (highest) day 1 [mg/dL] (mean ± SD)	1.15±0.77	1.21±1.13	1.24±0.79	1.38±1.03	1.88±0.83	<0.001
Hemoglobin day 1 [mmol/L] (mean ± SD)	6.79±0.77	6.81±0.80	6.66±0.83	6.58±0.85	6.13±0.91	<0.001
GFR (lowest) [mL/min/1.73 m^2] (mean ± SD)	78.31±25.29	76.02±23.54	69.64±24.75	63.04±25.03	41.63±21.52	<0.001
PRBC transfusion [units] (mean ± SD)	2.63±1.74	2.70±2.20	2.62±1.42	3.11±2.22	4.62±3.04	<0.001

Note: The statistical analysis showed p>0.05, therefore this is statistically not significant (NS).

Abbreviations: BMI, body mass index; CK, creatinine kinase MB fraction; CPB, cardio-pulmonary bypass; FFP, fresh frozen plasma; GFR, glomerular filtration rate; n, number of patients; NS, not significant; NYHA, New York Heart Association; PRBC, packed red blood cells; PTCA, percutaneous coronary angioplasty.

Table 2 Primary and secondary outcomes data for each intubation time cohort

Postoperative outcomes	Intubation time
	0–6 hours (n=148)	6.1–9 hours (n=329)	9.1–12 hours (n=511)	12.1–24 hours (n=846)	>24.1 hours (n=70)	P-value
Primary outcome data
Mortality – 30 days, n (%)	7 (4.73)	5 (1.52)	8 (1.57)	31 (3.66)	11 (15.71)	<0.001
Hospital LOS (mean ± SD)	7.05±2.82	7.77±5.35	7.80±4.25	9.13±11.73	15.89±19.63	<0.001
ICU LOS (mean ± SD)	2.23±0.76	2.49±2.77	2.38±1.63	2.96±5.10	7.37±12.31	<0.001
Secondary outcome data – complications
Stroke, n (%)	2 (1.35)	4 (1.22)	4 (0.78)	19 (2.25)	11 (15.71)	<0.001
TIA, n (%)	1 (0.68)	3 (0.91)	4 (0.78)	10 (1.18)	0 (0)	NS
Delirium, n (%)	15 (10.14)	25 (7.6)	56 (10.96)	140 (16.55)	15 (21.43)	<0.001
Seizures, n (%)	1 (0.68)	0 (0.00)	0 (0.00)	3 (0.35)	4 (5.71)	<0.001
Cardiogenic shock, n (%)	3 (2.03)	2 (0.61)	5 (0.98)	16 (1.89)	12 (17.14)	<0.001
Pneumonia, n (%)	1 (0.68)	7 (2.13)	10 (1.96)	35 (4.14)	18 (25.71)	<0.001
Respiratory failure, n (%)	6 (4.05)	12 (3.65)	16 (3.13)	48 (5.67)	34 (48.57)	<0.001
AKI, n (%)	7 (4.73)	4 (1.22)	17 (3.33)	46 (5.44)	18 (25.71)	<0.001
AKI requiring hemofiltration, n (%)	7 (4.73)	14 (4.26)	15 (2.94)	64 (7.57)	26 (37.14)	<0.001
Atrial fibrillation, n (%)	32 (21.62)	55 (16.72)	110 (21.53)	186 (21.99)	15 (21.43)	NS
Sepsis, n (%)	1 (0.68)	0 (0.00)	1 (0.20)	1 (0.12)	2 (2.68)	<0.001

Abbreviations: AKI, acute kidney injury; ICU, intensive care unit; LOS, length of stay; n, number of patients; P, statistical significance; TIA, transient ischaemic attack.

Table 3 Differences in 30-day mortality for different intubation time-points

Mortality at 30 days	OR	95% CI	P-value
Intubation time 0–6 hours	0.661	0.271–1.614	NS
Intubation time 6–9 hours	0.916	0.341–2.460	NS
Intubation time 9–12 hours	1.513	0.620–3.692	NS
Intubation time 12–24 hours	2.831	1.216–6.594	0.016
Intubation time >24 hours	8.514	3.283–22.079	0.000

Abbreviations: NS, not significant; P, statistical significance.

Table 4 Baseline characteristics and perioperative data for patients intubated for ≤12 hours and >12 hours during and after CABG

Data	Intubation time
	≤12 hours (n=988)	>12 hours (n=916)	P-value
Demographic data
Age [years] (mean ± SD)	64.43±8.04	68.25±8.05	<0.001
BMI [kg/m^2] (mean ± SD)	29.14±4.37	28.72±4.32	NS
Gender, male, n (%)	824 (83.40)	663 (72.38)	<0.001
Smoking, n (%)	185 (18.78)	126 (13.83)	<0.001
BMI, n (%)
Normal	156 (15.79)	180 (19.48)	NS
Overweight	439 (44.43)	397 (42.97)
Obesity	393 (39.78)	347 (37.55)
Admission type, n (%)
Elective	679 (68.79)	632 (68.40)	NS
Accelerated	244 (24.72)	235 (25.43)
Emergency	64 (6.48)	65 (7.09)
Concomitant diseases
Ejection fraction <30%, n (%)	60 (6.07)	60 (6.55)	NS
NYHA III and IV, n (%)	85 (9.71)	110 (13.45)	0.016
Diabetes mellitus, n (%)	451 (45.65)	433 (47.27)	NS
Glucose intolerance, n (%)	33 (3.34)	35 (3.82)	NS
Transient ischemic attack, n (%)	9 (0.91)	13 (1.42)	NS
Stroke, n (%)	61 (6.17)	52 (5.68)	NS
Arterial hypertension, n (%)	730 (73.89)	704 (76.86)	NS
Myocardial infarction, n (%)	506 (51.21)	509 (55.57)	NS
PTCA/Stenting, n (%)	340 (34.41)	287 (31.33)	NS
Atrial fibrillation paroxysmal, n (%)	57 (5.77)	63 (6.88)	NS
Atrial fibrillation persistent, n (%)	35 (3.54)	29 (3.17)	NS
Internal carotid artery stenosis, n (%)	60 (6.07)	83 (9.06)	0.013
COPD, n (%)	53 (5.36)	56 (6.11)	NS
Chronic renal failure, n (%)	52 (5.26)	57 (6.22)	NS
Acute renal failure, n (%)	0 (0.0)	6 (0.66)	0.032
Extracardiac arteriopathy, n (%)	160 (16.19)	179 (19.54)	NS
Operative risk
EuroScore Logistic 2 [%] (mean ± SD)	2.05±2.23	2.63±3.88	<0.001
Preoperative factors
Ejection fraction [%] (mean ± SD)	46.85±9.9	46.86±10.11	NS
CKMB [U/L] (mean ± SD)	25.10±24.38	37.76±100.09	NS
Hemoglobin [mmol/L] (mean ± SD)	8.57±0.93	8.40±0.96	<0.001
Creatinine [mg/dL] (mean ± SD)	0.98±0.58	1.06±0.77	0.004
GFR [mL/min/1.73 m^2] (mean ± SD)	83.24±25.76	76.65±31.01	<0.001
Intraoperative factors
CPB time [min] (mean ± SD)	50.29±14.23	50.81±18.60	NS
Aortic cross-clamping time [min] (mean ± SD)	30.54±9.65	29.74±9.48	NS
Reoperation, n (%)	19 (1.92)	59 (6.44)	<0.001
Intraoperative hemofiltration, n (%)	160 (16.19)	212 (23.14)	<0.001
Postoperative factors
CKMB day 1 [U/L] (mean ± SD)	56.19±58.75	81.20±167.04	NS
Drainage day 1 [mL] (mean ± SD)	454.27±303.23	502.10±472.26	NS
Creatinine [highest] day 1 [mg/dL] (mean ± SD)	1.22±0.91	1.42±1.02	<0.001
Hemoglobin day 1 [mmol/L] (mean ± SD)	42.63±10.18	43.45±12.38	NS
GFR [lowest] day 1 [mL/min/1.73 m^2] (mean ± SD)	73.06±24.67	61.46±25.40	<0.001
PRBC transfusion, units (mean ± SD)	2.65±1.72	3.29±2.38	<0.001

Abbreviations: BMI, body mass index; CK, creatinine kinase MB fraction; CPB, cardio-pulmonary bypass; FFP, fresh frozen plasma; GFR, glomerular filtration rate; n, number of patients; NS, not significant; NYHA, New York Heart Association; PTCA, percutaneous coronary angioplasty; PRBC, packed red blood cells.

Table 5 Postoperative complications and mortality for patients intubated ≤12 and >12 hours

Postoperative outcomes	Intubation time
	≤12 hours (n=988)	>12 hours (n=916)	P-value
Primary outcome
Mortality at 30 days, n (%)	20 (2.02)	42 (4.59)	0.002
Hospital LOS, days (mean ± SD)	7.68±4.49	9.65±12.63	<0.001
ICU LOS, days (mean ± SD)	2.39±2.00	3.30±6.07	<0.001
Secondary outcome
Stroke, n (%)	10 (1.01)	30 (3.28)	<0.001
TIA, n (%)	8 (0.81)	10 (1.09)	0.69
Delirium, n (%)	96 (9.72)	155 (16.92)	<0.001
Seizures, n (%)	1 (1.01)	7 (0.76)	0.06
Cardiogenic shock, n (%)	10 (1.01)	28 (3.06)	0.003
Pneumonia, n (%)	18 (1.82)	53 (5.79)	<0.001
Respiratory failure, n (%)	34 (3.44)	82 (8.95)	<0.001
AKI, n (%)	28 (2.83)	64 (6.99)	<0.001
AKI requiring hemofiltration, n (%)	36 (3.64)	90 (9.83)	<0.001
Atrial fibrillation, n (%)	197 (19.94)	201 (21.94)	NS
Sepsis, n (%)	2 (0.20)	3 (0.33)	NS

Abbreviations: AKI, acute kidney injury; ICU, intensive care unit; LOS, length of stay; n, number of patients; NS, not significant; P, statistical significance; TIA, transient ischaemic attack.

Table 6 Univariate and multivariate analysis for intubation longer than 12 hours after CABG

	Univariate analysis		Multivariate analysis
	OR (95% CI)	P-value	OR (95% CI)	P-value
Primary outcomes
Mortality 30 days, n (%)	2.326 (1.355–3.992)	0.002	1.248 (0.628–2.480)	NS
Hospital LOS (mean ± SD)	1.044 (1.024–1.063)	<0.001	1.017 (0.996–1.034)	NS
ICU LOS (mean ± SD)	1.075 (1.034–1.119)	<0.001	1.030 (0.991–1.071)	NS
Secondary outcomes
Stroke, n (%)	3.312 (1.610–6.813)	0.001	1.416 (0.642–3.125)	NS
Delirium, n (%)	1.893 (1.441–2.485)	<0.001	1.548 (1.161–2.064)	0.003
Cardiogenic shock, n (%)	3.084 (1.489–6.385)	0.002	1.813 (0.800–4.107)	NS
Pneumonia, n (%)	3.310 (1.924–5.693)	<0.001	1.584 (0.844–2.974)	NS
Respiratory failure, n (%)	2.759 (1.830–4.159)	<0.001	1.159 (0.683–1.968)	NS
Acute Kidney Injury (AKI), n (%)	2.575 (1.636–4.054)	<0.001	1.158 (0.643–2.085)	NS
AKI requiring hemofiltration, n (%)	1.558 (1.240–1.959)	<0.001	1.302 (1.023–1.657)	0.032
Heart failure, n (%)	2.881 (1.936–4.288)	<0.001	1.349 (0.779–2.337	NS

Abbreviations: CABG, coronary artery bypass grafting; n, number of patients; ICU, intensive care unit; LOS, length of stay; P, statistical significance.