More on activity restrictions after surgery

In early January, I blogged about the dearth of evidence about activity restrictions after surgery.

A number of people commented and most agreed that there is little basis for most of the activity restrictions surgeons currently use.

An anonymous reader told me about a 2008 study from Creighton University that generated some interesting data about intra-abdominal pressures associated with some common activities. Here’s a summary of the paper.

The authors managed to find 10 healthy volunteers all of whom could bench press at least 100 pounds and were willing to have nasogastric manometry catheters placed and Foley catheters inserted into their urinary bladders.

Intra-abdominal pressures were recorded as each subject coughed 10 times as hard as possible, bench pressed varying amounts of weight from 26 to 114 pounds, and vomited after receiving ipecac syrup and drinking about 500 mL of water.

Pressures in the stomach and bladder correlated fairly well. To keep things simple, let’s look at gastric pressures only.

The highest mean and maximum pressures were found during vomiting. Coughing produced similar pressures. Most interestingly, intragastric pressures during weightlifting were significantly lower with a mean of 2 mmHg and a maximum of 52 mmHg, p <0 .001.="" br="">The authors mentioned that another group had found similar intra-abdominal pressures with subjects bench pressing 25 pounds.

Another unexpected finding was that although the differences were not significant, the mean intragastric pressures were inversely proportional to the amount of weight lifted.

Maybe we should tell postoperative patients not lift less than 26 lbs.

The authors were focused on measuring pressures that would disrupt a gastric anastomosis. They calculated that an intragastric pressure of 290 mmHg generated by vomiting was about 1/50 of the 20N [Newton] force that would disrupt a gastric suture line in a porcine model as demonstrated by other investigators.

The effect of repetitive stress such as found in patients with a chronic cough were unknown, but they said “the intra-abdominal pressures generated in our study alone do not appear to be responsible for hernia formation.”

The Creighton study authors concluded, "The common postoperative lifting restriction, although logical, has little evidence to support it." They called for more research in this area.

Unfortunately, their call has not been answered.

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