| Ancient custom: Surgeons still believe that eating may cause respiratory problems under anaesthesia
I remember all too well the agony of postsurgical starvation: nearly five days elapsed after my Caesarean section when the hospital refused to give me anything but ice chips. All the while I was trying to nurse two big babies with nothing but an intravenous glucose solution to sustain me. But the nurses held firm. I had not yet 'passed gas or had a bowel movement.'
Complaining bitterly, I asked, 'How can you expect my bowels to work if I'm not putting anything in them' I also remember my son's hunger and thirst as he waited 18 hours past midnight, the time of his last allowed intake of food or drink, for knee surgery that was supposed to have taken place that morning. We were hardly alone in our surgery-related distress. Most people having elective surgery are told 'nothing by mouth after midnight,' and it has long been common for hospitals to withhold food and drink from patients for days after surgery because their bowels were presumed to be still asleep.
I now know that my son and I, and most everyone else who has been in a similar situation, have suffered in vain. The stringent proscriptions on how long before, and how soon after, an operation patients can safely eat or drink was based on tradition, dogma and fear, not science. Once subjected to rigorous scientific study, the longstanding limitations on food and drink before and after surgery were found to be unnecessary and even detrimental.
'Medicine has changed substantially in the last 15 years,' Dr Michael L. Pearl, a gynaecological oncologist at the State University of New York at Stony Brook, said. 'Now evidence-based medicine is the norm.'
Pearl has been a leader in research that has changed medical thinking on how soon after surgery patients can safely be fed and what they can safely consume. He and others have clearly demonstrated that waiting until a patient can pass gas or move his bowels is counterproductive, resulting in longer and more costly hospital stays and greater patient discomfort.
Many researchers have also studied the amount of time patients should refrain from eating before surgery. Their findings prompted the American Society of Anaesthesiology in 1999 to revise its practice guidelines to permit clear liquids, a light meal or a regular meal often much closer to the expected time of surgery than the arbitrary advice to eat and drink nothing after midnight the day of an operation.
The big fear behind the original midnight proscription was that a patient under anaesthesia might vomit and aspirate, with serious respiratory consequences, if anything remained in the stomach during surgery. This may have been more likely before the advent of modern anaesthetics and better methods of administering them. Pulmonary aspiration is rare with modern anaesthesia. The revised guidelines permit clear liquids (water, clear tea, black coffee, carbonated beverages and fruit juice without pulp) two hours before scheduled surgery; breast milk four hours before; regular milk and infant formula or a light meal (like toast and clear liquids) six hours before, and a regular or heavy meal eight hours before.
In the article 'Preoperative Fasting: Old Habits Die Hard', published in The American Journal of Nursing three years after the anaesthesia society changed its guidelines, two nurses reported that 'our colleagues working in hospitals across the country report that ordering nothing by mouth after midnight is still the rule rather than the exception.'
The authors cited as explanations for this lag 'the inconvenie-nce of departing from traditional practice, the belief that longer fasts are better, the difficulty of individualising fasting instructi-ons, the concerns about changes in surgery schedules, the fear of litigation, the lack of concern about the adverse consequences of fasting, and the exaggerated concern about aspiration.'
To document the lag, the nurses interviewed 155 patients who had had elective surgery at the Presbyterian Hospital of Dallas, which had no policy on fasting. Most patients were told to take nothing by mouth after midnight regardless of their time of surgery. The nurses found that 'patients had fasted from liquids and solids for an average of 12 and 14 hours, respectively, with some patients fasting for as long as 20 hours from liquids and 37 hours from solids.'
The consequences of prolonged fasting are not trivial. Besides hunger, thirst and irritability, the researchers noted that some fasting patients also suffered from headaches, dehydration, low blood volume and low blood sugar. The nurses reported that other studies had found no difference in stomach contents between patients who had consumed coffee or juice two to three hours before surgery and those who had fasted overnight.
The traditionally long delays in feeding patients after surgery were prompted by a fear of complications, including postoperative nausea and vomiting, aspiration pneumonia and abdominal distension, Pearl said. The postoperative bowel was thought to be paralysed for hours, even days, particularly after abdominal or gynaecological surgery that involved moving the intestines.
But, he said, studies show the bowel continues to function even in surgery; in only 1 per cent to 2 per cent of patients does it shut down temporarily.