Pulmonary complications after abdominal surgery in patients with mild-to-moderate chronic obstructive pulmonary disease

Figures & data

Table 1 Baseline characteristics of study subjects classified by preoperative spirometry findings

	Control (n=86)	Mild-to-moderate COPD (n=117)	Severe-to-very severe COPD (n=34)	Restrictive (n=150)
Age (years)a	63.0 (57.0, 72.0)	69.0 (63.0, 75.0)	74.0 (71.0, 77.0)	68.0 (60.0, 75.0)
Gender (male)	45 (52.3)	100 (85.5)	29 (85.3)	84 (56.0)
Smoking history
Never	57 (66.3)	36 (30.8)	5 (14.7)	92 (61.3)
Current smoker	7 (8.1)	31 (26.5)	6 (17.6)	16 (10.7)
Past-smoker	22 (25.6)	50 (42.7)	23 (67.6)	42 (28.0)
Pack-yearsa	26.2 (15.0, 42.5)	30.0 (20.0, 47.0)	37.5 (25.0, 40.0)	30.0 (18.5, 40.0)
Body mass index (kg/m^2)a	22.7 (20.5, 24.6)	23.0 (21.0, 24.8)	22.4 (20.6, 25.2)	23.5 (20.3, 26.1)
Charlson comorbidity indexa	3.0 (2.0, 4.0)	3.0 (2.0, 5.0)	3.0 (2.0, 4.0)	3.0 (1.0, 4.0)
Charlson comorbidity index (age-adjusted)a	5.0 (4.0, 6.0)	5.0 (4.0, 7.0)	6.0 (5.0, 7.0)	5.0 (4.0, 6.0)
ASA physical status
1	2 (2.3)	9 (7.7)	4 (11.8)	10 (6.7)
2	68 (79.1)	72 (61.5)	24 (70.6)	80 (53.3)
3	14 (16.3)	29 (24.8)	4 (11.8)	47 (31.3)
4	2 (2.3)	7 (6.0)	2 (5.9)	13 (8.7)
History
Upper respiratory infection	3 (3.5)	4 (3.4)	0 (0.0)	3 (2.0)
Hospitalization due to respiratory problem	5 (5.8)	8 (6.8)	3 (8.8)	8 (5.3)
Exacerbation of COPD	0 (0.0)	0 (0.0)	3 (8.8)	0 (0.0)
Respiratory symptoms	10 (11.6)	26 (22.2)	14 (41.2)	18 (12.0)
Chronic cough	7 (8.1)	10 (8.5)	6 (17.6)	6 (4.0)
Chronic sputum	4 (4.7)	7 (6.0)	5 (14.7)	5 (3.3)
Dyspnea (mMRC)
1	1 (1.2)	3 (2.6)	4 (12.1)	3 (2.0)
2	1 (1.2)	8 (6.9)	7 (21.2)	6 (4.0)
3	1 (1.2)	3 (2.6)	1 (3.0)	2 (1.3)
4	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)
Laboratory finding
Blood urea nitrogen (mg/dL)a	14.0 (11.0, 17.0)	14.0 (11.0, 18.0)	13.5 (9.0, 21.0)	14.0 (10.0, 18.0)
Creatinine (mg/dL)a	0.7 (0.6, 0.9)	0.8 (0.7, 1.0)	0.8 (0.7, 1.0)	0.8 (0.6, 1.0)
Albumin (g/dL)a	3.4 (3.0, 3.7)	3.3 (3.0, 3.7)	3.0 (2.8, 3.3)	3.1 (2.8, 3.5)
Preoperative spirometry
FVC (L)a	3.2 (2.7, 4.0)	3.2 (2.8, 3.7)	2.4 (2.0, 2.8)	2.1 (1.7, 2.7)
FVC (% pred)a	90.5 (83.0, 99.0)	80.0 (70.0, 91.0)	60.0 (49.0, 71.0)	59.0 (52.0, 68.0)
FEV1 (L)a	2.5 (2.2, 3.0)	1.8 (1.6, 2.3)	1.1 (0.9, 1.3)	1.7 (1.3, 2.1)
FEV1 (% pred)a	97.0 (86.0, 106.0)	66.0 (57.0, 78.0)	40.5 (37.0, 45.0)	65.0 (57.0, 77.0)
FEV1/FVCa	0.78 (0.75, 0.81)	0.62 (0.56, 0.65)	0.46 (0.38, 0.56)	0.79 (0.75, 0.85)
DLco (% pred)b	74.8±15.1	69.1±22.1	48.0±18.2	55.6±16.5

Notes: Data are presented as numbers (%) unless otherwise indicated.

a Median (interquartile range)

b mean ± standard deviation. COPD grade is defined as follows: mild-to-moderate COPD, FEV₁ ≥50% predicted with FEV₁/FVC <0.7; severe-to-very-severe COPD, FEV₁ <50% predicted with FEV₁/FVC <0.7. Restrictive disease is defined as FVC <80% predicted with FEV₁/FVC ≥0.7.

Abbreviations: ASA, American Society of Anesthesiologists; COPD, chronic obstructive pulmonary disease; DLco, diffusing capacity for carbon monoxide; FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity; mMRC, modified Medical Research Council Dyspnea Scale; pred, predicted.

Figure 1 Flow diagram for patient requirement.

Table 2 Characteristics of abdominal surgery performed on study subjects

	Control (n=86)	Mild-to-moderate COPD (n=117)	Severe-to-very severe COPD (n=34)	Restrictive (n=150)
Emergency surgery	7 (8.1)	11 (9.4)	4 (11.8)	19 (12.7)
Anesthesia time (min)a	240.5 (143.0, 335.0)	233.0 (116.0, 319.0)	148.0 (101.0, 190.0)	187.5 (110.0, 362.0)
Incision to closure time (min)a	169.0 (92.0, 269.0)	175.0 (77.0, 250.0)	106.5 (64.0, 145.0)	129.0 (66.0, 292.0)
Laparoscopic surgery	24 (27.9)	43 (36.8)	18 (52.9)	60 (40.0)
Upper abdominal surgery	53 (61.6)	87 (74.4)	26 (76.5)	109 (72.7)
RBCs for transfusion (pack)a	2.0 (2.0, 2.0)	2.0 (2.0, 2.0)	1.0 (0.0, 2.0)	2.0 (0.0, 4.0)

Notes: Data are presented as numbers (%) unless otherwise indicated.

a Median (interquartile range). COPD grade is defined as follows: mild-to-moderate COPD, FEV₁ ≥50% predicted with FEV₁/FVC <0.7; severe-to-very severe COPD, FEV₁ <50% predicted with FEV₁/FVC <0.7. Restrictive disease is defined as FVC <80% predicted with FEV₁/FVC ≥0.7.

Abbreviations: COPD, chronic obstructive pulmonary disease; FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity; RBC, red blood cell.

Table 3 Postoperative pulmonary complications and management

	Control (n=86)	Mild-to-moderate COPD (n=117)	Severe-to-very-severe COPD (n=34)	Restrictive (n=150)	P-value
Postoperative pulmonary complications	13 (15.1)	14 (12.0)	9 (26.5)	27 (18.0)	0.204
Pneumonia	9 (10.5)	7 (6.0)	4 (11.8)	12 (8.0)	0.590
Pulmonary edema	3 (3.5)	5 (4.3)	4 (11.8)	13 (8.7)	0.174
Pulmonary thromboembolism	1 (1.2)	0 (0.0)	0 (0.0)	1 (0.7)	0.671
Atelectasis	4 (4.7)	3 (2.6)	2 (5.9)	10 (6.7)	0.484
Acute exacerbation of COPD	0 (0.0)	1 (0.9)	0 (0.0)	0 (0.0)	0.510
ICU admission	11 (12.8)	11 (9.4)	12 (35.3)	47 (31.3)	<0.001
ICU admission due to respiratory cause	5 (45.5)	3 (27.3)	3 (27.3)	15 (31.9)	0.772
Length of ICU admission (days)a	2.0 (2.0, 15.5)	4.0 (2.5, 20.5)	1.0 (1.0, 3.5)	7.0 (1.0, 15.5)	0.041
Ventilator care	9 (10.5)	8 (6.8)	5 (14.7)	35 (23.3)	0.001
Length of ventilator care (days)a	2.0 (1.0, 13.0)	6.0 (2.0, 33.0)	1.0 (1.0, 6.0)	6.0 (2.0, 29.5)	0.214
Ventilator care over 3 days	4 (44.4)	5 (62.5)	2 (40.0)	23 (65.7)	0.526
Readmission within 30 days	10 (11.8)	6 (5.1)	0 (0.0)	15 (10.1)	0.081
Readmission due to respiratory cause	0 (0.0)	0 (0.0)	0 (0.0)	3 (20.0)	0.170
In-hospital mortality	2 (2.3)	4 (3.4)	0 (0.0)	3 (2.0)	0.683
In-hospital mortality + mortality within 30 days	2 (2.4)	4 (3.4)	0 (0.0)	4 (2.7)	0.752
Overall mortality	2 (2.4)	4 (3.4)	1 (3.0)	9 (6.1)	0.532
Expired due to respiratory problems	0 (0.0)	2 (50.0)	0 (0.0)	1 (11.1)
Duration operation to discharge (days)a	9.0 (6.0, 14.0)	9.0 (5.0, 16.0)	7.5 (4.0, 13.0)	9.0 (5.0, 18.0)	0.431
Duration admission to discharge (days)a	17.0 (13.0, 25.0)	18.0 (11.0, 26.0)	16.0 (9.0, 19.0)	19.0 (12.0, 33.0)	0.092

Notes: Data are presented as numbers (%) unless otherwise indicated.

a Median (interquartile range). COPD grade is defined as follows: mild-to-moderate COPD, FEV₁ ≥50% predicted with FEV₁/FVC <0.7; severe-to-very severe COPD, FEV₁ <50% predicted with FEV₁/FVC <0.7. Restrictive disease is defined as FVC <80% predicted with FEV₁/FVC ≥0.7.

Abbreviations: COPD, chronic obstructive pulmonary disease; FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity; ICU, intensive care unit.

Table 4 Risk factors for postoperative pulmonary complications in all subjects

	Univariate	Multivariate (all variables entered)	Multivariate (stepwise backward elimination)
	OR (95% CI)	OR (95% CI)	OR (95% CI)
Age	0.99 (0.97–1.02)	1.04 (1.00–1.08)
Gender (male)	0.58 (0.30–1.05)	1.59 (0.72–3.55)
Body mass index	0.96 (0.89–1.03)	0.97 (0.88–1.06)
Charlson comorbidity index	1.19 (1.03–1.36)*	1.05 (0.87–1.27)
ASA physical status	2.57 (1.76–3.80)***	1.52 (0.90–2.58)	1.60 (0.97–2.63)
Hospitalization within 1 year due to respiratory illness	3.43 (1.38–8.12)**	3.77 (1.35–10.57)*	4.20 (1.52–11.59)**
BUN	1.03 (1.01–1.05)**	1.00 (0.98–1.03)
Emergency surgery	5.93 (2.96–11.85)***	4.28 (1.82–10.05)**	3.93 (1.75–8.82)**
Anesthesia time	1.00 (1.00–1.00)***	1.00 (1.00–1.00)
Laparoscopic surgery	0.26 (0.12–0.52)***	0.52 (0.21–1.24)	0.41 (0.18–0.93)*
Upper abdominal surgery	1.02 (0.57–1.89)	0.79 (0.36–1.72)
RBCs for transfusion	1.12 (1.08–1.17)***	1.09 (1.02–1.16)**	1.09 (1.05–1.14)***
Mild-to-moderate COPD	0.76 (0.34–1.72)	0.57 (0.21–1.59)	0.79 (0.31–2.03)
Severe-to-very severe COPD	2.02 (0.77–5.30)	2.27 (0.68–7.56)	3.47 (1.16–10.42)*
Restrictive disease	1.23 (0.60–2.54)	0.71 (0.28–1.77)	0.81 (0.33–1.97)

Notes: COPD grade is defined as follows: mild-to-moderate COPD, FEV₁ ≥50% predicted with FEV₁/FVC <0.7; severe-to-very-severe COPD, FEV₁ <50% predicted with FEV₁/FVC <0.7. Restrictive disease is defined as FVC <80% predicted with FEV₁/FVC ≥0.7.

* P<0.05;

** P<0.01;

*** P<0.001.

Abbreviations: ASA, American Society of Anesthesiologists; BUN, blood urea nitrogen; CI, confidence interval; COPD, chronic obstructive pulmonary disease; FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity; OR, odds ratio; RBC, red blood cell.

Table 5 Risk factors for postoperative pulmonary complications only in ever-smokers without restrictive pattern (a subgroup analysis)

	Univariate	Multivariate (all variables entered)	Multivariate (stepwise elimination)
	OR (95% CI)	OR (95% CI)	OR (95% CI)
Age	1.01 (0.95–1.07)	1.06 (0.97–1.17)
Body mass index	0.91 (0.77–1.08)	0.91 (0.72–1.16)
Charlson comorbidity index	1.17 (0.92–1.48)	1.24 (0.89–1.73)
ASA physical status	2.14 (1.07–4.27)*	0.92 (0.26–3.22)
Hospitalization within 1 year due to respiratory illness	14.25 (3.42–73.03)***	28.21 (3.85–206.51)**	18.75 (3.47–101.25)**
BUN	1.03 (0.98–1.07)	0.97 (0.88–1.07)
Emergency surgery	5.11 (1.51–16.71)**	3.95 (0.73–21.43)	3.92 (0.89–17.26)
Anesthesia time	1.00 (1.00–1.01)**	1.00 (0.99–1.01)
Laparoscopic surgery	0.33 (0.07–1.04)	0.27 (0.05–1.68)
Upper abdominal surgery	1.02 (0.36–3.33)	1.67 (0.33–8.54)
RBCs for transfusion	1.14 (1.06–1.31)*	1.20 (0.95–1.53)	1.17 (1.02–1.34)*
Mild-to-moderate COPD	0.42 (0.13–1.34)	0.26 (0.05–1.39)	0.34 (0.08–1.50)
Severe-to-very-severe COPD	1.46 (0.43–4.91)	2.06 (0.35–12.01)	1.85 (0.42–8.24)

Notes: COPD grade is defined as follows: mild-to-moderate COPD, FEV₁ ≥50% predicted with FEV₁/FVC <0.7; severe-to-very-severe COPD, FEV₁ <50% predicted with FEV₁/FVC <0.7. Restrictive disease is defined as FVC <80% predicted with FEV₁/FVC ≥0.7.

* P<0.05;

** P<0.01;

*** P<0.001. The variable Gender (male) was omitted in this table, because the subgroup had only 2 female patients.

Abbreviations: ASA, American Society of Anesthesiologists; BUN, blood urea nitrogen; CI, confidence interval; COPD, chronic obstructive pulmonary disease; FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity; OR, odds ratio; RBC, red blood cell.

Table S1 Comparison of baseline characteristics in patients with and without postoperative pulmonary complications

	No postoperative pulmonary complications (n=324)	Postoperative pulmonary complications (n=63)	P-value
Age (years)a	69.0 (61.0, 75.0)	68.0 (60.5, 74.0)	0.411
Gender (male)	210 (64.8)	48 (76.2)	0.108
Smoking history			0.894
Never	160 (49.4)	30 (47.6)
Current smoker	49 (15.1)	11 (17.5)
Past-smoker	115 (35.5)	22 (34.9)
Pack-yearsa	30.0 (20.0, 40.0)	30.0 (20.0, 45.0)	0.920
Body mass index (kg/m^2)a	23.2 (20.8, 25.4)	22.0 (19.5, 24.6)	0.049
Charlson comorbidity indexa	2.0 (2.0, 4.0)	3.0 (3.0, 4.0)	<0.001
Charlson comorbidity index (age-adjusted)a	5.0 (4.0, 6.5)	6.0 (5.0, 7.0)	0.007
ASA physical status			<0.001
1	25 (7.7)	0 (0.0)
2	214 (66.0)	30 (47.6)
3	72 (22.2)	22 (34.9)
4	13 (4.0)	11 (17.5)
History
Upper respiratory infection	8 (2.5)	2 (3.2)	1.000
Hospitalization due to respiratory problem	15 (4.6)	9 (14.3)	0.009
Exacerbation of COPD	2 (0.6)	1 (1.6)	0.985
Respiratory symptoms	59 (18.2)	9 (14.3)	0.570
Chronic cough	27 (8.3)	2 (3.2)	0.245
Chronic sputum	19 (5.9)	2 (3.2)	0.577
Dyspnea (mMRC)			0.096
1	10 (3.1)	1 (1.6)
2	21 (6.5)	1 (1.6)
3	4 (1.2)	3 (4.9)
4	0 (0.0)	0 (0.0)
Laboratory finding
Blood urea nitrogen (mg/dL)a	14.0 (10.0, 17.5)	16.0 (12.5, 22.5)	0.001
Creatinine (mg/dL)a	0.8 (0.6, 0.9)	0.9 (0.7, 1.1)	0.009
Albumin (g/dL)a	3.3 (2.9, 3.6)	3.3 (2.9, 3.7)	0.384
Preoperative spirometry
FVC (L)a	2.8 (2.1, 3.4)	2.8 (2.1, 3.3)	0.903
FVC (% pred)a	73.8±19.3	71.4±18.3	0.356
FEV (L)a 1	1.9 (1.5, 2.4)	1.8 (1.4, 2.4)	0.813
FEV1 (% pred)a	69.0 (57.0, 87.0)	71.0 (53.5, 81.5)	0.437
FEV1/FVCa	0.73 (0.63, 0.80)	0.76 (0.64, 0.82)	0.624
DLco (% pred)b	65.2±20.1	44.9±17.1	0.014

Notes: Data are presented as numbers (%) unless otherwise indicated.

a Median (interquartile range),

b mean ± standard deviation.

Abbreviations: ASA, American Society of Anesthesiologists; COPD, chronic obstructive pulmonary disease; DLco, diffusing capacity for carbon monoxide; FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity; mMRC, modified Medical Research Council Dyspnea Scale; pred, predicted.

Table S2 Differences in surgical characteristics between patients with and without postoperative pulmonary complications

	No postoperative pulmonary complications (n=324)	Postoperative pulmonary complications (n=63)	P-value
Emergency operation	22 (6.8)	19 (30.2)	<0.001
Anesthesia time (min)a	190.0 (110.0, 300.0)	310.0 (157.5, 687.5)	<0.001
Incision to close time (min)a	132.0 (68.5, 243.5)	230.0 (115.0, 575.0)	<0.001
Laparoscopic surgery	135 (41.7)	10 (15.9)	<0.001
Upper abdominal surgery	230 (71.0)	45 (71.4)	1.000
RBCs for transfusion (pack)a	2.0 (0.0, 2.0)	3.0 (2.0, 16.5)	<0.001

Notes: Data are presented as numbers (%) unless otherwise indicated.

a Median (interquartile range).

Abbreviation: RBC, red blood cell.

Table S3 Differences in postoperative management and outcomes between patients with and without postoperative pulmonary complications

	No postoperative pulmonary complications (n=324)	Postoperative pulmonary complications (n=63)	P-value
ICU admission	41 (12.7)	40 (63.5)	<0.001
Length of ICU admission (days)a	2.0 (1.0, 6.0)	13.0 (4.0, 28.5)	<0.001
Ventilator care	23 (7.1)	34 (54.0)	<0.001
Length of ventilator care (days)a	2.0 (1.0, 3.0)	12.0 (3.0, 31.0)	0.003
Ventilator care in over 3 days	8 (34.8)	26 (76.5)	0.004
Readmission within 30 days	25 (7.8)	6 (9.5)	0.829
Readmission due to respiratory cause	0 (0.0)	3 (50.0)	0.003
In-hospital mortality	2 (0.6)	7 (11.1)	<0.001
In-hospital mortality + mortality within 30 days	3 (0.9)	7 (12.1)	<0.001
Overall mortality	7 (2.2)	9 (15.5)	<0.001
Duration operation to discharge (days)a	8.0 (5.0, 13.0)	26.0 (13.0, 43.5)	<0.001
Duration admission to discharge (days)a	16.0 (11.0, 24.0)	41.0 (24.0, 61.5)	<0.001

Notes: Data are presented as numbers (%) unless otherwise indicated.

a Median (interquartile range).

Abbreviation: ICU, intensive care unit.