Risk of VTE increases with duration of surgery

Consider it one more reason to make that surgery a quick one. Researchers found that the longer a surgery goes, the more risk of venous thromboembolism (VTE) for the patient.

The study, published online Dec. 3 in JAMA: Surgery, found that compared with average length procedures, the longest ones carried a 1.27-fold greater risk for patient development of pulmonary embolism or deep vein thrombosis.

John Y. S. Kim, MD, of the Department of Surgery at Northwestern University’s Feinberg School of Medicine in Chicago, and colleagues wrote that much like inactivity in to a long flight allows blood flow to slow and pool, prolonged surgery had a similar result.

Kim et al reviewed patient data found in the American College of Surgeons’ National Surgical Quality Improvement Program (NSQIP) database. The NSQIP database provided information from more than 300 institutions on a range of patient variables, including type of surgery, length from start to emergence from anesthesia and development and type of VTE.

Of the more than 1.4 million patient cases reviewed between 2005 to 2011, 0.96 percent developed a VTE of some type. Pulmonary embolism occurred in 0.33 percent of patients and deep vein thrombosis in 0.71 percent. A very small fraction of patients (0.08 percent) developed both types of VTE. They found a range of five time groups, from shortest to longest, for assigning risk.

Relatively short procedures had odds for developing VTEs between 0.86 and 0.98 compared to midrange surgery lengths. Longer procedures had increasingly higher odds, between 1.1 and 1.27. For every standard deviation increase in surgical time, they noted an increase in odds by 1.12.

Among the surgical procedure types reviewed, the ones that bore the highest risk of VTE included cardiothoracic and neurological surgeries. Cardiothoracic VTE incidence was 1.44 percent and 3.49 percent for shortest and longest procedures, respectively. Meanwhile, among neurological procedures the shortest and longest procedures had incident rates of 1.04 percent and 2.86 percent, respectively.

The lowest incidence of VTE occurred in otolaryngologic procedures, the shortest duration yielding 0.11 percent while the longest 0.67 percent.

They also noted that among the three most common types of surgeries, laparoscopic appendectomy, cholecystectomy, and gastric bypass, one hour increases to surgery times significantly increased risk for VTE (odds ratio: 1.18, 1.18 and 1.26, respectively).

Kim et al noted that their findings confirmed suspicions long held in the community. In a press release, Kim stated, "Minute by minute, hour by hour, the trend is much more pervasive and consistent than any of us believed it could be.”

The team suggested using a quintile approach to assessing surgery lengths and risk. They noted these findings might improve VTE risk modeling and enhance both prophylaxis guidelines and surgical decision-making.