Risk of Pulmonary Complications After Elective Abdominal Surgery

Risk of Pulmonary Complications After Elective Abdominal Surgery* Valerie A. Lawrence, MD; Rahul Dhanda, PhD; Susan G Hilsenbeck, PhD; and Carey P. Page, MD

Study objective: Intra-abdominal operations are relatively high risk for pulmonary complications.

Previous research has more intensely investigated cardiac operative risk, but recent work suggests that significant pulmonary complications may be more common than cardiac complications and as¬ sociated with longer length of stay. This study identified risk indicators for pulmonary complications

after elective abdominal operations. Design: Nested case-control. Setting: University affiliated Veterans Affairs hospital. Patients: We used a computerized registry of all 2,291 patients undergoing elective abdominal op¬ erations from 1982 to 1991. Ascertainment and verification of pulmonary and cardiac complications were systematic and explicit. Charts of all 116 patients identified by the registry as having compli¬ cations and 412 (19%) randomly selected from 2,175 remaining patients were reviewed to verify complications, using explicit criteria and independent abstraction of preoperative and postopera¬ tive components of charts. From 528 validated subjects (23% of the cohort), 82 cases and 82 con¬ trol subjects were closely matched by operation type and age, ± 10 years. Measurements and results: The primary outcome measure was postoperative pulmonary complica¬ tions. Among 82 cases with pulmonary complications, 27 (33%) also had cardiac complications. Preoperative variables independently associated with pulmonary complications by multivariable analysis (p<0.05) included the following: Charlson comorbidity index (per point odds ratio [OR], 1.6; 95% confidence interval [CI], 1.004 to 2.6), Goldman cardiac risk index (per point OR, 2.04; 95% CI, 1.17 to 3.6), abnormal chest radiograph (OR, 3.2; 95% CI, 1.07 to 9.4), and abnormal findings on lung examination (OR, 5.8; 95% CI, 1.04 to 32). Equal proportions of cases and control subjects had preoperative diagnostic spirometry. No component of spirometry predicted complications, in¬ cluding severity of obstructive lung disease. Conclusions: For pulmonary operative risk, abnormal results of lung examination and chest radiog¬ raphy plus cardiac and overall comorbidity were important. Spirometry was not helpful. Because 33% of cases had both cardiac and pulmonary complications, future studies should prospectively examine comparative incidence, outcomes, and predictors of both types of complications. (CHEST 1996; 110:744-50) cardiac complications; preoperative care; pulmonary complications; pulmonary function testing; surgery/oper¬ Keywords: ative Abbreviations: ASA=American Society of Anesthesiology7; CI=confidence interval; OR=odds ratio

intra-abdominal operations Ti/|"orearethan 3.5 million in the United States each year.1,2 performed These are associated with It A

procedures

relatively high

For editorial comment

pulmonary

rates of and cent work suggests that

see

page 587

cardiac complications.3"5 Re¬ pulmonary complications may

*From Audie L. Murphy Division, South Texas Veterans Health Care System and the University of Texas Health Science Center at San Antonio: Divisions of General Medicine (Drs. Lawrence and Dhanda) and Oncology (Dr. Hilsenbeck), Department of Medi¬ cine, and Department of Surgerv (Dr. Page), San Antonio, Tex. Affairs Health Services Research and De¬ Supported by Veterans 88-166. velopment, received grant IIRNovember 6, 1995; revision accepted May 7, Manuscript 1996. 744

be as or more common than cardiac complications and associated with longer length of stay.6 Although phy¬ sicians involved in preoperative evaluation can base cardiac risk assessment on extensive research, their ability to assess pulmonary operative risk is limited for several reasons. First, cardiac operative risk has been more rigor¬ ously and extensively studied than pulmonary opera¬

risk.6

monthly computerized terms (preoperative care or postoperative complica¬ tions), studies of cardiac risk from noncardiac surgery outnumbered those of pulmonary risk approximately 3:1.6 Of those studies focusing on pulmonary compli¬ cations, many have been eclipsed by modern supporttive

In

a

continuous

literature search from 1987 to 1994, using broad search

Clinical

Investigations

technology or had problems in design.7,8 Methodologic problems in the literature include poor standardization and definition of postoperative pulmo¬ nary complications, inadequate blinding of observers, selection bias, and reporting of clinically unimportant complications such as microatelectasis.7'8 Although recently published investigations have used better study designs, they are limited by size and heteroge¬ neous pretest probabilities due to surgical case mix.9"11 To address these problems, we used nested case-con¬ trol design12 to identify preoperative indicators of pulmonary risk in a large cohort of patients undergo¬ ive

care

ing elective abdominal operations. Materials

and

Methods

Study Cohort/Ascertainment of Cases This study was approved by the Institutional Review Board at the

University of Texas Health Science Center at San Antonio. The patient cohort included all elective intra-abdominal operations performed between 1982 and 1991 (n=2,291) at Audie L. Murphy Division of the South Texas Veterans Health Care System. This fa¬ cility is a 650-bed hospital affiliated with the University of Texas

Health Science Center at San Antonio and has a large South Texas catchment area. Patients were identified from a computerized registry of all general surgical procedures, which includes postop¬ erative complications occurring prior to discharge from the surgery

service.

We surveyed the surgical registry for both pulmonary and cardiac complications for two reasons: (1) some patients might have both types of complications but only one might be listed in the registry, and (2) misclassification of type of complication in the registry. Two major types of misclassification could exist in the registry: errors in classifying patients as having or not having complications and errors in type of complication (ie, cardiac or pulmonary). Therefore, we used an explicit, systematic strategy to ascertain and verify compli¬ cations. This strategy included the following: chart review of all patients listed by the registry as having pulmonary or cardiac com¬ plications; chart review for 412 randomly selected patients listed as not having complications (19% of the cohort); identical exclusion criteria for cases and control subjects; and a systematic chart review process. The chart review process included the following: a trained research nurse with established expertise in chart abstraction; explicit criteria for postoperative and pulmonary complications; abstraction of postoperative chart sections that was independent of, or blinded to, preoperative and intraoperative portions of the chart; and a second independent review by the senior author of 21% (n=110) of all charts reviewed. Agreement beyond chance between the two independent re¬ views was calculated using the Kappa statistic. Among eligible pa¬ tients, agreement was 100% (Kappa=1.0) on whether patients were classified as cases (pulmonary or cardiac complications.see below for definition) or control subjects (no complication). Among cases, Kappa was 0.81 (excellent agreement) as to whether individual complications were pulmonary or cardiac. Cases were defined as patients undergoing elective abdominal operations who, after chart validation, had intraoperative or post¬ operative pulmonary complications (with or without cardiac com¬ plications) as defined by explicit criteria (see Appendix 1). These included pneumonia, respiratory failure, bronchospasm, tracheobronchitis, and pleural effusion requiring thoracentesis. Cardiac complications included myocardial infarction, ischemia, congestive

heart failure, supraventricular tachycardia and ventricular dysrhyth¬ mia requiring therapy, and cardiogenic shock. Patients whose only postoperative pulmonary event was microat¬ electasis or macroatelectasis were excluded as either cases or con¬ trol subjects (n=59). Microatelectasis is not considered clinically important, while the clinical significance of macroatelectasis is un¬ clear. We defined explicit criteria for both and identified matched control subjects for all 59. Although hospital, ICU, and ventilator days were not significantly different between all available control subjects and patients with microatelectasis or macroatelectasis, we conservatively excluded them as both cases and control subjects. Each case was matched to a control subject by type of surgery (Table 1) and age (within 10 years). Matching was done to avoid bias in determining risk factors for complications due to age or specific types of surgery, which are well known to affect operative risk. Al¬ though matching by these factors resulted in a small sample size, it allowed us to unmask their effect and identify other potentially important risk factors. Of the 2,291 elective abdominal operations in the cohort, 116 were reported by the registry as having pulmonary or cardiac com¬ plications. After chart validation of these 116 potential cases, 80 remained as true cases, and 36 were excluded from analysis: 8, no postoperative complication; 2, complication already present preoperatively; 3, uniquely high-risk conditions (myasthenia gravis, amyotrophic lateral sclerosis, quadriplegia); 1, multiple complica¬ tions with stay in the ICU of 151 days; 6, operation not elective laparotomy; 7, microatelectasis or macroatelectasis only; and 9, chart unavailable. From the remaining 2,175 patients in the cohort, 412 without reported complications were randomly selected from a computerized list stratified by type of operation. After validation of the 412 possible controls, 32 were excluded (1, complication present preoperatively; 2, operation not elective laparotomy; 29, microatelectasis or macroatelectasis only) and 27 who actually had pulmonary or cardiac complications were reclassified as cases. Thus, the final eligible sample pool was 107 (80+27). Of these, we were unable to find matched control subjects for 11 cases. All of these had consistently undergone procedures of especially high pulmonary risk: six Whipple procedures, two esophagectomies, one esophagogastrectomy, and two gastric resections. Lastly, the 14 patients with only cardiac complications were ex¬ cluded from analyses of predictors of pulmonary complications. Therefore, the total number of verified cases with pulmonary complications (with or without cardiac complications) for whom matched control subjects were found was 82. Overall, the total number of charts reviewed in detail to verify presence or absence of complications was 519, 23% of the entire cohort. Data were abstracted from the medical record for preoperative, intraoperative, and postoperative variables identified in previous studies as potential predictors of complications.9"11,13"34 Besides history, examination, and laboratory data, preoperative variables included the cardiac risk index of Goldman et al,13 the American Society of Anesthesiology (ASA) physical status index, and the Charlson comorbidity index.32"34 Data on lung examination were abstracted from the preoperative progress note closest to surgery and were defined as normal (no abnormalities noted) or abnormal (decreased breath sounds, prolonged expiration, or adventitial sounds such as rales, rhonchi, or wheezes). Data on chest radio¬ graphs were based on the official reading of the preoperative radiograph closest to surgery, if available, or the progress notes. If no official reading was available and progress notes disagreed, the most abnormal reading noted was used. Chest radiographs were categorized as normal or abnormal for hyperinflation, pulmonary hypertension, vascular redistribution or edema, atelectasis, effusion, infiltrate, other parenchymal abnormalities, multiple abnormalities, or other. These categories were initially mutually exclusive, but because of small sample size, they were collapsed into normal or abnormal for analyses. CHEST 7110/3/ SEPTEMBER, 1996

745

Table 1.Characteristics of Cases With Pulmonary Complications and Control Subjects* (n=82) 65 (±9)

Control Subjects

Cases

Age, yr, mean (±SD) Types of laparotomy, n

Biliary operations* Esophageal procedures Gastric procedures Pancreatic operations Aortic resection or graft Colectomy, partial and total Abdominoperineal resection Exploratory/staging laparotomy, enterolysis Anesthesia time, min, mean (±SD) Operation time, min, mean (±SD) Deaths, nj Length of stay, d, mean (±SD)| ICU

stay, d, mean (±SD)|

Ventilator time, d, mean (±SD)| Goldman cardiac risk score, mean (±SD)

Comorbidity score, mean (±SD)f Pack-years smoking, mean (±SD)

Preoperative spirometry done (%)

FEVb L, mean (±SD) Percent predicted FEVi, mean (±SD) FVC, L, mean (±SD) Percent predicted FVC, mean (±SD) FEVi/FVC, mean (±SD) Pco2, mean (±SD) P02, mean (±SD)

Degree of obstructive disease (%)

13 9 12 5 21 15 2 5 248 (±87) 188 (±83) 0 10.5 (±6) 1.5 (±1.5) 0.2 (±0.4) 3.9 (±1.9) (p=0.017) 1.5 (±1.5) 34 (±42) (p=0.03) 38 (±46) 2.6 (±1.7) 77 (±29) 3.6 (±1.5) 75 (±25) 66 (±17)

273 (±123) 205 (±112)

18 26.4 (±29) 6.3 (±8.4 3.2 (±7.5) 4.9 (±2.6) 2.7 (±1.8) 47 (±36) 39 (±48) 2.4 (±1.3) 72 (±25) 3.6 (±1.3) 77 (±22) 66 (±20) 35 (±7) 76 (±16)

or mild Moderate

35±8)

79 (±25)

27 (69) 10 (26)

32 (84)

6(16)

2(5)

Severe *

64 (±9)

13 9 12 5 21 15 2 5

None

(n=82)

0

Unmatched descriptive analyses.

^Fourteen open cholecystectomies, no laparoscopic cholecystectomies.

*p<0.001.

Preoperative spirometry was obtained in 48% of cases and 46% of control subjects. When spirometric data were available, presence and severity of obstructive lung disease were defined according to the FEVi/FVC ratio, as follows: 75 or greater, normal; 60 to 74, mild obstruction; 40 to 59, moderate obstruction; and less than 40, se¬ vere obstructive disease. Other than spirometric data, the preva¬ lence of missing data was very low (2%). There were no missing data for 81% ofvariables. For 13% of variables, data were more than 98% complete and for the remaining 6%, data were more than 90%

complete.

Statistical Methods For descriptive analyses, we used x2 tests for categorical variables and Student's t tests for continuous variables. To identify preoper¬ ative risk indicators of postoperative pulmonary complications, we did univariate analyses with matched, bivariate conditional logistic regressions because cases and control subjects were closely matched by type of operation and age. We then used Spearman correlation coefficients to scan for closely correlated, or colinear, variables to avoid multicolinearity in the final regression models. Colinear vari¬ ables would be closely associated with both pulmonary complica¬ tions and each other and so cause instability in multivariable regression models. To then identify independent risk indicators of pulmonary com¬ plications, we used multivariable conditional logistic regression analysis. Based on the "rule of 10" outcomes for each independent variable to be entered in the regression models, we limited the

746

variables eligible for entry into the regression models to the eight preoperative variables most significantly associated with pulmonary complications on matched univariate analyses.35,36 Analyses were performed using SAS software SAS Institute, Inc; Cary, NC).

Results

Table 1 shows overall characteristics of the 82 cases and 82 control subjects according to unmatched descriptive analyses. All 18 deaths occurred among cases. Hospital and ICU stays were significantly longer for cases than control subjects. Cases had significantly worse comorbidity scores and greater mean pack-years of smoking compared with control subjects. Preoper¬ ative diagnostic spirometry was obtained in similar proportions of cases (48%) and control subjects (46%), but no single spirometric variable was associated with Cases did not differ from pulmonary complications. control subjects in the proportion having preoperative

diagnostic spirometry, mean FEVi, mean FVC, mean FEVi/FVC, or results of arterial blood gas analysis. The

of obstructive disease (none or mild vs moder¬ degree ate or severe) was also not associated with complica¬ but statistical is low and there was a trend

tions,

power

Clinical

Investigations

Table 2.Types ofPulmonary Complications

Types of

Complications

(%) 37 (30) 36 (29) 22 (18) 15 (12) 11(9) 3(2)

No.

Respiratory failure

Pneumonia

Possible pneumonia Effusion Tracheobronchitis

Bronchospasm Total

124

toward more patients with moderate or severe disease among cases compared with control subjects. Table 2 shows the specific pulmonary complications in the 82 cases. Of these, 55 had pulmonary compli¬ cations and 27 (33%) had both pulmonary and cardiac severe pulmo¬ complications. Of the 54 patients with and/or respiratory nary complications (pneumonia failure), 18 also had cardiac complications. Of the 18 patients who died, 11 had both cardiac and pulmo¬ nary complications. Of the 37 cases of respiratory fail¬ ure, 17 (46%) were not associated with cardiac com¬

plications.

Table 3 shows the variables that were significantly associated with pulmonary complications in univariate some of these variables are clini¬ Although analyses. to other (eg, smoking, dyspnea, his¬ related each cally of abnormal results of pulmonary disease, tory lung examination, abnormal chest radiography), none were sufficiently collinear by Spearman correlation coeffi¬ cients to exclude as candidates for multivariable anal¬

ysis.

Multivariable conditional logistic regression was then used to identify preoperative variables indepen¬ dently associated with pulmonary complications. EliTable 3.Preoperative Variables Significantly Associated With Pulmonary Complications on Univariate Analysis

(p<0.05)

OR

Charlson comorbidity

0.0001

(95% CI) 2.0 (1.4-2.9)

Abnormal results of lung

0.0020

4.6 (1.7-12.1)

Abnormal chest radiograph History of hypertension Goldman cardiac risk index, per point History of dyspnea History of lung disease History of renal disease History of cardiac disease ASA class, per class Pack-years smoking, per

0.0022 0.0031 0.0035

p Value

index, per point examination

5-yr increment

23.2 (1.5-6.8)

5.8 (1.8-18.8) 1.5 (1.1-2.0)

0.0097 3.3 (1.3-8.3) 0.0118 3.0 (1.3-7.1) 0.0123 12.1 (1.7-84.8) 0.0152 1.5 (1.1-2.0) 0.0210 0.0288

1.9 (1.1-3.3) 1.1 (1.04-1.06)

Table 4.Variables Independently Associated With Cardiac Complications by Multivariable Pulmonary and Conditional Logistic Regression: All Pulmonary Complications

(82 Cases/82 Control Subjects) Variable

Abnormal results of

OR*

95% CI

5.8

1.04-32.1

Value 0.045

pulmonary examination 0.038 3.2 1.07-9.4 Abnormal chest radiograph 2.04 0.01 1.17-3.6 Goldman cardiac risk indexf 1.6 0.048 1.004-2.6 Charlson comorbidity index1 Adjusted OR for beta coefficient. * Adjusted OR per point on Goldman cardiac risk index and Charlson comorbidity index. *

from Table 3 were first limited to those gible regressors associated with pulmonary complications significantly at p<0.01. Then three additional models were built to see if history of lung, renal, or cardiac disease (0.01
In this study of veterans undergoing elective ab¬ dominal operations, preoperative clinical factors inde¬ pendently associated with pulmonary complications included abnormal results of lung examination or ab¬ normal chest radiograph, the Goldman cardiac risk index, and overall comorbid disease burden as mea¬ sured by the Charlson comorbidity index. Abnormal CHEST / 110 / 3 / SEPTEMBER, 1996

747

spirometric findings were not associated with compli¬

multivariable analysis. The of obstructive degree lung disease (none/mild vs did not contribute to the multivari¬ moderate/severe) able model for pulmonary complications, even with forcing it into the model. Cases were closely matched to control subjects by age and type of surgery to unmask the effect of these well-recognized risk factors and identify other potentially important variables associated with pulmonary complications. These re¬ sults suggest that composite comorbidity and lung disease sufficiently severe to result in an abnormal finding on an examination or abnormal radiography are better indicators of risk than spirometry. The signifi¬ cance of cardiac comorbidity may have resulted from the frequency of combined pulmonary and cardiac complications in 33% of the patients in this study. Clinicians should be aware of several issues in interpreting these results. First, cardiac operative risk has been more rigorously and extensively studied than pulmonary risk.6 Although large prospective studies of cardiac risk have been done since 1977,13 with deriva¬ tion and validation of cardiac risk indexes,13,14 large and rigorous studies to identify risk factors for pulmonary complications are relatively lacking.6 The only preop¬ erative pulmonary risk index ofwhich we are aware was as follows: (1) hypothesized, with all components arbitrarily weighted equally, and tested in a small study (n=42) of patients undergoing resection for lung can¬ cer; (2) not validated in a larger patient population or patients undergoing nonthoracic surgery; and (3) ac¬ tually combined with the cardiac risk index of Goldman et al13 to generate a summary score for predicting both cardiac and pulmonary complications.37 The high prevalence of combined pulmonary and cardiac com¬ plications in our patient population suggests that such a combined index may be useful. However, we did not test the index in our study because it includes the FEVi/FVC ratio and a measure of PaC02 (in addition to body mass index, smoking, productive cough, and wheezing or rhonchi). Therefore, using the index requires a priori spirometric and arterial blood gas data. We think a more useful goal is to identify clini¬ cal risk factors from history and physical examination that would clearly discriminate between patients who do and do not warrant further workup to assess risk, such as spirometry or arterial blood gases. Second, it is not clear why this discrepancy in research about cardiac and pulmonary operative risk has occurred. Recent work suggests that pulmonary be as or more frequent than cardiac complications may and with longer stays in ICUs associated complications and the hospital.6 Further, the clinical importance of combined pulmonary and cardiac complications may cations

748

on

univariate

or

be relatively unrecognized.6 The prominence of com¬ bined complications in this study may partially explain why our measure of cardiac comorbidity was signifi¬ cantly associated with pulmonary complications. Rig¬ orous prospective and sufficiently large studies to document incidence and impact of cardiac, pulmonary, and combined complications are needed. Third, although widely used to assess pulmonary operative risk before abdominal operations, spirome¬ try maybe less helpful than other clinical variables. The fact that spirometiy did not independendy predict complications in our study may have been biased by the fact that mean lung function was fairly good (as shown in Table 1) and that spirometry was available for less than 50% of cases and control subjects. Despite this small sample size, frequency of spirometry was evenly distributed among cases (48%) and control subjects (46%), suggesting poor discriminatory ability among physicians in selecting which patients should have preoperative spirometry. Further, a growing body of evidence suggests (1) that spirometry may not be as predictive as often assumed and (2) that spirometry may be overutilized./_11'38 In a comprehensive system¬ atic review of the evidence regarding spirometry before abdominal operations, the predictive value of spirometry for postoperative pulmonary complications was found to be unproved.7 Previous studies suffered from significant methodologic flaws and/or were con¬ ducted before the availability of current technologies in

supportive care.7,8

designed studies suggest that preoperative spirometry does not predict individual risk of complications. One study is the largest surgical cohort patients of with severe COPD of which we are aware.9 In this retrospective study, 107 patients toler¬ ated noncardiac surgery relatively well despite severe COPD on spirometry.9 In a study of 278 patients un¬ dergoing elective general surgery (of which 70% had abdominal operations), preoperative spirometry was not helpful in identifying patients at increased pulmo¬ nary operative risk.11 Kroenke et al10 compared rates of complications in patients with severe COPD, mod¬ erate disease, and normal lung function undergoing surgery. Patients with severe COPD had rates of car¬ diac, vascular, and minor pulmonary complications similar to patients with mild-moderate disease and without COPD, but they had significandy higher rates of serious pulmonary complications and death. Nota¬ failure in patients with bly, all death and respiratory severe COPD occurred in the subgroup undergoing coronary artery bypass surgery. Factors significantly associated with cardiac or serious pulmonary compli¬ cations included age older than 70 years, perioperative bronchodilator use, abnormal chest radiographs, and More recent, better

Clinical Investigations

ASA classification.10

Spirometry was not an indepen¬

dent indicator of risk. Because the ASA classification system is a subjective global rating of comorbid disease burden, these findings are consistent with the present study's results regarding composite comorbidity and abnormal chest radiography. Despite the growing evidence that preoperative

screening spirometry is not uniformly helpful, recent

work indicates it may be overutilized.38 In an inclusive sample of 441 spirometries from a large urban military hospital, 31% (135) complete tests were done preoperatively. Of these, 52 (39%) did not meet current guidelines from the American College of Physi¬ cians.3940 Results of spirometry in 48 of the 52 patients were normal or showed mild abnormalities. One case of severe obstructive disease and no cases of moderate obstructive disease or severe restrictive disease were found in patients for whom spirometry was not indi¬ cated by American College of Physicians Guidelines.38 Last, this study has several important methodologic limitations and therefore the findings should be con¬ sidered preliminary. Limitations include the following: (1) a male veteran population with a high prevalence of smoking and chronic obstructive lung disease; (2) data collection by chart audit; (3) small sample size; and (4) lack of a uniform prospective surveillance strategy for complications. Several strategies reduced potential bias due to these limitations. All cases and control subjects were validated by chart abstraction using explicit criteria for complications and independent abstraction of the preoperative and postoperative components of charts. Patients reported by the surgical registry as having 19% of the re¬ cardiopulmonary complications pluswere control reviewed to maining potential subjects validate all potential cases and control subjects. Over¬ all, charts were reviewed for 23% of the cohort. Sam¬ chose to: (1) focus on a ple size is small because wewith more homogeneous relatively high-risk group overall risk (ie, abdominal operations) than a mixed surgical population, and (2) closely match on age and type of procedure. In conclusion, evidence of lung disease on physical examination and chest radiography plus cardiac disease and composite comorbidity indicated increased pul¬ monary risk in this study of veterans undergoing elec¬ tive abdominal operations. Consistent with a growing body of evidence, preoperative spirometry did not help identify patients at increased risk. If true, reduced use of spirometry coupled with improved definition of specific subgroups who may benefit could improve risk assessment and result in substantial savings. Such subgroups might include patients with obvious disease on examination who have never had diagnostic spirom¬ etry or patients in whom especially severe disease is

rationale is supported by recent work suspected.thatThismoderate COPD can be reliably diag¬ showing nosed on the basis of history and physical examina¬ tion.41,42 However, patients with good functional status and normal results of examination may not benefit from routine preoperative spirometry. Finally, we think that research on pulmonary operative risk lags behind that for cardiac risk assessment. Future re¬ search should prospectively assess incidence, out¬ comes, and predictors for both pulmonary and cardiac of noncardiac/nonthoracic surgery. Fi¬ complications the yield of preoperative nally, valid assessment ofeither a randomized trial of would

require spirometry preoperative spirometry vs no spirometry or a pro¬ spective cohort study in which patients with pulmonary risk factors (eg, known pulmonary disease, smoking history, abnormal results of pulmonary examination) all receive preoperative spirometry and complications are

defined by explicit objective criteria.

Appendix 1: Criteria for Pulmonary and Cardiac Complications

Pulmonary

1. Pneumonia: radiographic evidence and antibiotics 2. Possible pneumonia: radiographic evidence but no IV antibiot¬ ics OR normal chest radiograph, but IV antibiotics given 3. Respiratory failure: ventilator dependence for >1 postoperative

day or reintubation

4. Bronchospasm: clinical diagnosis resulting in change in therapy 5. Tracheobronchitis: purulent sputum with normal chest radio¬ graph, not treated with IV antibiotics 6. Pleural effusion: resulting in thoracentesis

Cardiac 1. Transient ischemia:

2. 3. 4. 5. 6.

7.

8. 9.

cian

angina or ECG read as ischemia by physi¬

Supraventricular tachycardia: resulting in pharmacologic inter¬ or care in the ICU Ventricular ectopy: resulting in therapy Transmural myocardial infarction: increased MB fraction of creatinine phosphokinase plus Q waves or characteristic ST el¬ evation on ECG Nontransmural myocardial infarction: increased MB fraction plus ST depression or T-wave changes on ECG for more than 24 h Possible infarction: suspected but criteria for transmural or nontransmural infarction not satisfied Congestive heart failure: clinical evidence (eg S3 gallop, rales, increased jugular venous pressure) or radiographic changes AND change in therapy with diuretic, inotropic, or afterloadreducing agents Cardiogenic shock: systolic BP <90 mm Hg, clinical and radiographic evidence, and pressor agents Cardiopulmonary arrest: includes ventricular fibrillation

vention

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