Pulmonary Complications of Major Abdominal Surgery May Be Increasing in US

Laurie Barclay, MD

May 31, 2007

May 31, 2007 (Dallas) — The number of pulmonary complications after major abdominal surgery increased in the United States between 1989 and 2004, according to a presentation at the Society for Hospital Medicine annual meeting.

"Stratified by age group, pulmonary complications increased predominantly in women aged 45 to 64 years, but they also increased in both men and women aged 65 years and older," author and presenter Carlos H. Orces, MD, a rheumatologist at the University of Texas Health Science Center at San Antonio, told Medscape. "Logistic regression analysis adjusted by age and sex showed that overall pulmonary complications increased in the US during the study period. However, specific complications, such as pneumonia, ARDS [acute respiratory distress syndrome], and respiratory failure, increased significantly, whereas atelectasis and pleural effusions decreased over time."

Although pulmonary complications after abdominal surgery cause significant morbidity and mortality and prolong hospital stays, there are few data available concerning national trends in postoperative pulmonary complications.

Dr. Orces used the National Hospital Discharge Survey to generate estimates of selected abdominal operations and postoperative pulmonary complications in all patients 18 years of age and older who underwent abdominal surgery between 1989 and 2004. Specific procedures evaluated were splenectomy, gastrectomy, vagotomy, partial excision of the large intestine, total colectomy, appendectomy, abdominal perineal resection of the rectum, cholecystectomy, radical pancreaticoduodenectomy, and exploratory laparatomy.

Postoperative pulmonary complications were defined as pneumonia, atelectasis, respiratory failure, ARDS, and pleural effusion. The Mantel-Haenszel test for trend was used to determine the proportion of postoperative pulmonary complications after abdominal surgery, stratified by sex and age, during the following periods: 1989-1992, 1993-1996, 1997-2000, and 2001-2004.

In the United States between 1989 and 2004, the estimated number of major abdominal operations performed was 12,897,800. Postoperative pulmonary complications occurred after surgery in 388,400 men (7.8%), mean age 63 ± 16.9 years, and in 452,800 women (5.7%), mean age 65 ± 17.2 years.

The proportion of pulmonary complications was higher in men than in women and increased exponentially with age. Mean hospital stay was 16 ± 18.1 days for patients with pulmonary complications and 6 ± 8.5 days for those without complications. In-hospital mortality after abdominal surgery was 3.1% in men (n = 155,300) and 1.9% in women (n = 152,800). However, the case-fatality rates for men (1.0 vs 2.1) and women (0.7 vs 1.3) with pulmonary complications remained relatively low.

Trend analysis showed that pulmonary complication rates increased significantly during the study period for all age groups, except for men younger than 45 years and men between 45 and 64 years. Overall, the odds ratio (OR) for pulmonary complications during the 2001-2004 period vs the 1989-1992 period was 1.21 (95% confidence interval [CI], 1.21 - 1.22).

"This study gives statistically important data [for] 15 years' experience, and demonstrates an increasing rate of postoperative pulmonary complications following abdominal operations through the years both in men and women," Fikret Kanat, MD, a pulmonologist in the Department of Chest Diseases, Meram Medical School of Selcuk University, in Konya, Turkey, told Medscape. Dr. Kanat was not involved in this study, but was asked to provide independent commentary.

"It is interesting to see higher complication rates through the years despite new surgical techniques," Dr. Kanat said. "Higher complication rates through the years may be a result of more aggressive surgeries defined for various malignant diseases."

Pneumonia, ARDS, and respiratory failure increased significantly over the 4 time periods of the study, whereas atelectasis and pleural effusions decreased over time.

"I do not have a clear explanation [for] these findings; however, the use of postoperative incentive spirometry may explain, in part, the decrease in rates for atelectasis," Dr. Orces said. "I believe further research should be focused on surgical procedures at risk for pulmonary complications. For example, I found that upper abdominal surgeries, such as gastrectomy and vagotomy, are associated with a higher proportion of pulmonary complications (up to 40%)."

Compared with the 1989-1992 period, the 2001-2004 period was associated with increased odds ratios for pneumonia (OR, 1.31; 95% CI, 1.29 - 1.32), ARDS (OR, 2.56; 95% CI, 2.51 - 2.61), and respiratory failure (OR, 2.24; 95% CI, 2.21 - 2.28), but decreased odds ratios for atelectasis (OR, 0.86; 95% CI, 0.86 - 0.87) and pleural effusions (OR, 0.58; 95% CI, 0.57 - 0.59).

In terms of future research, both Dr. Orces and Dr. Kanat recommended additional analyses adjusted for comorbid conditions such as chronic obstructive pulmonary disease or asthma.

"This study may be broadened by assessing the relationship of various pulmonary complications with operation types," Dr. Kanat said. "Through the years, operations for malignant diseases have increased, and postoperative pulmonary complications following such surgeries may be more specific than the others. Pulmonary complications following laparoscopic surgeries may also be compared with the other types."

Dr. Orces and Dr. Kanat report no relevant financial relationships.

Hospital Medicine 2007: Abstract 49. May 23-25, 2007.



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