Risk Factors and Short-Term Outcomes of Postoperative Pulmonary Complications in Elderly Patients After Cardiopulmonary Bypass

Figures & data

Table 1 The Characteristics of Patients

Characteristic	Total (n = 660)	Non-PPCs (n = 285)	PPCs (n = 375)	P value
Age, years	68 (66, 70)	68 (66, 70)	68 (66, 71)	0.74
Age ≥75 years	54 (8.18)	21 (7.37)	33 (8.8)	0.506
Male	378 (57.27)	172 (60.35)	206 (54.93)	0.163
BMI ≥28 kg/m^2	54 (8.18)	26 (9.12)	28 (7.47)	0.442
Drinking history	155 (23.48)	76 (26.67)	79 (21.07)	0.093
Smoking history	196 (29.7)	84 (29.47)	112 (29.87)	0.913
FEV1/FVC ratio, %	72.52 (66.37, 77.84)	73.26 (67, 78.3)	71.98 (66.08, 77)	0.108
FEV1/FVC ratio <70%	273 (41.36)	109 (38.25)	164 (43.73)	0.156
LVEF, %	61 (57, 65)	61 (57, 65)	62 (58, 66)	0.133
LVEF <50%	57 (8.64)	21 (7.37)	36 (9.6)	0.312
EuroScore	4 (3, 5)	4 (3, 5)	3 (3, 5)	< 0.001
EuroScore				0.012
≤ 2	125 (18.94)	67 (23.51)	58 (15.47)
3–5	415 (62.88)	176 (61.75)	239 (63.73)
≥6	120 (18.18)	42 (14.74)	78 (20.8)
Hypertension	301 (45.61)	124 (43.51)	177 (47.2)	0.346
Diabetes	103 (15.61)	43 (15.09)	60 (16)	0.749
Coronary artery disease	336 (50.91)	133 (46.67)	203 (54.13)	0.057
Myocardial infarction	32 (4.85)	12 (4.21)	20 (5.33)	0.506
Cerebrovascular disease	43 (6.52)	17 (5.96)	26 (6.93)	0.618
Pulmonary hypertension	21 (3.18)	9 (3.16)	12 (3.2)	0.976
Atrial fibrillation	169 (25.61)	70 (24.56)	99 (26.4)	0.592
Positive inotropic drug use	19 (2.88)	9 (3.16)	10 (2.67)	0.709
Antibiotic use	127 (19.24)	62 (21.75)	65 (17.33)	0.154
Surgical incision				0.077
Median sternotomy	607 (91.97)	256 (89.82)	351 (93.6)
Minimally invasive	53 (8.03)	29 (10.18)	24 (6.4)
Type of surgery				< 0.001
CABG	96 (14.55)	52 (18.25)	44 (11.73)
CABG + Valve	171 (25.91)	53 (18.6)	118 (31.47)
Valve	362 (54.85)	172 (60.35)	190 (50.67)
Aorta	31 (4.7)	8 (2.81)	23 (6.13)
CPB time	110 (85, 137)	108 (84, 129)	112 (86, 150)	0.004
CPB time >150 min	123 (18.64)	31 (10.88)	92 (24.53)	< 0.001
Aortic cross-clamp time	70 (50, 91)	68 (49, 87)	74 (52, 95)	0.026
Aortic cross-clamp time >120 min	54 (8.18)	14 (4.91)	40 (10.67)	0.008
Duration of surgery, min	248 (210, 312.25)	240 (195, 295)	265 (213, 327)	< 0.001
Duration of surgery, min				0.001
<180	59 (8.94)	33 (11.58)	26 (6.93)
180–240	255 (38.64)	125 (43.86)	130 (34.67)
>240	346 (52.42)	127 (44.56)	219 (58.4)
Duration of anesthesia, min	311 (263, 375)	298 (251, 356)	325 (271, 395)	< 0.001
Duration of anesthesia >240 min	554 (83.94)	228 (80)	326 (86.93)	0.016
Blood transfusion	405 (61.36)	159 (55.79)	246 (65.6)	0.01
Use of IABP before extubation	29 (4.39)	2 (0.7)	27 (7.2)	< 0.001
Hemoglobin, g/L	124.60±16.45	125.8±15.42	123.69±17.16	0.102
Anemia	333 (50.45)	144 (50.53)	189 (50.4)	0.974
Platelet count, *10^9/L	169 (131, 208)	172 (135, 212)	167 (126.5, 204.5)	0.116
Lymphocyte count, *10^9/L	1.61 (1.28, 2)	1.62 (1.31, 2.03)	1.6 (1.28, 1.96)	0.274
Neutrophil count, *10^9/L	3.12 (2.54, 4.06)	3.17 (2.5, 4.06)	3.07 (2.57, 4.08)	0.993
Monocyte count, *10^9/L	0.43 (0.34, 0.56)	0.44 (0.33, 0.56)	0.42 (0.34, 0.56)	0.651
Serum albumin, g/L	39.54±3.60	39.97±3.44	39.21±3.68	0.007
Serum albumin <40 g/L	366 (55.45)	143 (50.18)	223 (59.47)	0.017
Aspartate transaminase, U/L	22 (18, 28)	21 (18, 26)	22 (18, 29)	0.209
Aspartate transaminase >40 U/L	35 (5.3)	14 (4.91)	21 (5.6)	0.696
Alanine transaminase, U/L	19 (14, 28)	18 (14, 28)	19 (14, 28)	0.967
Alanine transaminase >40 U/L	67 (10.15)	36 (12.63)	31 (8.27)	0.066
Serum creatinine, µmol/L	77.8 (66.35, 92.6)	76.3 (65.8, 91.9)	79.1 (67, 93.2)	0.159
Serum creatinine >133 µmol/L	30 (4.55)	11 (3.86)	19 (5.07)	0.461
Urea nitrogen, mmol/L	6.19 (5.16, 7.65)	6.15 (5.21, 7.53)	6.22 (5.14, 7.72)	0.589
Urea nitrogen >7.5 mmol/L	180 (27.27)	73 (25.61)	107 (28.53)	0.404
eGFR, mL/min/1.73m^2	78.14±18.85	80.14±18.40	76.62±19.07	0.017
eGFR <60 mL/min/1.73m^2	121 (18.33)	42 (14.74)	79 (21.07)	0.037

Note: Data are presented as mean (SD) or median (interquartile range) or number of patients (%). Anemia was defined as hemoglobin < 130 g/L for men or < 120 g/L for women.

Abbreviations: BMI, body mass index; FEV1/FVC, forced expiratory volume in one second/forced vital capacity; LVEF, left ventricular ejection fraction; EuroScore, European System for Cardiac Operative Risk Evaluation; CABG, coronary artery bypass grafting; CPB, cardiopulmonary bypass; IABP, intra-aortic balloon pump; eGFR, estimated glomerular filtration rate.

Figure 1 Specific distribution of missing variables. (A) Proportion of missing variables. The missing rate varied from 0.6% to 14.5%; (B) Quantification of missing values across different combinations of variables. Red squares indicate missing data.

Abbreviations: BMI, body mass index; FEV1/FVC, forced expiratory volume in one second/forced vital capacity; eGFR, estimated glomerular filtration rate.

Table 2 Multivariable Logistic Regression for Predictors of PPCs

Variables	OR	95% CI	P value
EuroScore
≤ 2	Reference
3–5	1.4	0.91–2.14	0.126
≥6	1.47	0.82–2.63	0.196
Serum albumin <40 g/L	1.43	1.03–1.98	0.032
eGFR <60mL/min/1.73m^2	1.38	0.89–2.14	0.147
Type of surgery
CABG	Reference
CABG + Valve	2	1.14–3.51	0.016
Aorta	2.6	1.01–6.7	0.047
Valve	1.49	0.9–2.44	0.119
CPB time >150 min	1.93	1.01–3.66	0.046
Aortic cross-clamp time >120 min	0.87	0.37–2.06	0.753
Duration of surgery, min
<180	Reference
180–240	1.34	0.7–2.54	0.379
>240	1.59	0.77–3.27	0.214
Duration of anesthesia >240 min	1.04	0.61–1.76	0.893
Blood transfusion	1.44	1.03–2.01	0.033
Use of IABP before extubation	7.36	1.69–32.07	0.008

Abbreviations: PPCs, postoperative pulmonary complications; OR, odds ratio; CI, confidence interval; EuroScore, European System for Cardiac Operative Risk Evaluation; eGFR, estimated glomerular filtration rate; CABG, coronary artery bypass grafting; IABP, intra-aortic balloon pump.

Figure 2 Distribution of PPCs in the Study. (A) Proportion of various PPCs: The incidences of individual pulmonary complications, ranked from highest to lowest, were pulmonary infection, pleural effusion requiring thoracic drainage, postoperative mechanical ventilation lasting more than 48 hours, ARDS, and re-intubation. (B) Incidence of multiple PPCs in patients. Most patients experienced a single pulmonary complication, with fewer individuals exhibiting various categories of pulmonary complications.

Abbreviations: PPCs, postoperative pulmonary complications; ARDS, acute respiratory distress syndrome.

Table 3 Comparison of Short-Term Outcomes in Patients with and without PPCs

Variables	Total (n = 660)	Non-PPCs (n = 285)	PPCs (n = 375)	P value
Length of hospitalization, days	30 (24, 38)	27 (22, 33)	33 (26, 42)	< 0.001
Length of postoperative hospitalization, days	16.5 (13, 21)	15 (12, 18)	18 (14, 24)	< 0.001
ICU length of stay, days	4 (3, 5)	3 (2, 4)	5 (4, 7)	< 0.001
Length of postoperative mechanical ventilation, hours	27 (21, 46)	24 (20, 33)	42 (23.5, 63)	< 0.001
Death, %	25 (3.79)	3 (1.05)	22 (5.87)	0.001
Dialysis, %	5 (0.76)	0 (0)	5 (1.33)	0.133
Cerebral infarction, %	2 (0.3)	2 (0.7)	0 (0)	0.186
Tracheotomy, %	33 (5)	1 (0.35)	32 (8.53)	< 0.001

Note: Data are presented as median (interquartile range) or number of patients (%).

Abbreviation: ICU, intensive care unit.