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Department of Anesthesiology and Intensive Care, Karolinska Hospital and Institute, se-171 76 Stockholm, Sweden
Address correspondence to Sten GE Lindahl, MD, Department of Anesthesiology and Intensive Care, Karolinska Hospital and Institute, SE-171 76 Stockholm, Sweden. Address e-mail to sten.lindahl{at}kirurgi.ki.se
There is attraction and fascination in professions with dynamic attitudes and willingness to change dogmas. Certainly, this is true for anesthesiology. We too, however, have our "Sacred Cows." The practice of preoperative fasting routines has resided comfortably in its stall for a long time. Rarely have anesthesiologists discussed how to loosen the strict "NPO from midnight" rule, which came to embrace not only solid foods but also fluids. It took an article by Hestor and Heath in 1977 (1) focused on the pulmonary aspiration syndrome, gastric pH, and fluid volume to question whether prophylaxis against aspirations should be routine. Then, Miller et al. (2) found in 1983 that a light breakfast 2–4 h before surgery did not negatively influence gastric pH and fluid volume. After this, publications by Maltby et al. (3–5) appeared in the late 1980s and early 1990s suggesting that "NPO from midnight" should only apply to solids. Even during the early 1990s, however, bellowing from the cow’s stall preserved the dogma for some time. Today, the scenario has changed. In elective cases we allow a light breakfast for patients scheduled at lunchtime or in the afternoon and fluids are allowed until 2 h before scheduled surgery (6). This gradual paradigm shift opened up new possibilities and initiatives. In this issue of Anesthesia & Analgesia, Hausel et al. (7) report that they used a special carbohydrate-rich preoperative drink and clearly demonstrated improved preoperative thirst, hunger, and anxiety as compared with a placebo group and a group that was fasted overnight. The improvements could be achieved without side effects and the study points out new directions that we must more actively investigate.
There are, by now, several well-designed studies showing that preoperative drinks up to 2 h before surgery are safe. It must, however, be emphasized that such guidelines do not apply to emergency or acute situations, when opioids have been used for severe pain, or in cases where an imbalance within the sympathetic nervous system is obvious. All these factors prolong gastric emptying and retard gastrointestinal motility. Obstetric units must also have sound and safe routines for all deliveries because a relatively large number of parturients require some kind of anesthesia. Also, in a corner of the stall there is still a bucket of cows’ milk reminding us that such milk, in neonates and young infants, empties the stomach slower than human milk. Otherwise, there are no particular deviations in preoperative fasting routines for elective pediatric cases from those discussed above. Still, however, a large controlled prospective, randomized multicenter study on new preoperative fasting routines, covering several thousand patients, is lacking.
From a practical point of view it is indeed hard to see any major obstacles to changing preoperative nutritional routines. For in-hospital patients a new routine can easily be implemented. It is only a matter of organization and administration. The practical problem arises in all elective patients for same-day admissions. Again, these problems are mostly organizational and rest upon detailed patient information with regard to timing and the composition of the light meal or fluid. Perhaps it is also legitimate in a context such as this to provide strong support for patient information about how best to prepare for any elective surgical trauma in terms of the best possible physical activity and healthy living. The question now is to find scientific evidence for preoperative actions and how they relate to innate immunity, inflammatory responses, wound healing, temperature balance, insulin resistance, catabolism, and length of hospital stay. The Hausel study (7) sheds some light on these matters and stimulates new questions for future studies. It also suggests a reduced preoperative anxiety and hence a diminished need for anxiolytic premedicants. The study certainly shows that there is absolutely no need for the relatively insufficient sedative effect achieved by morphine. Further, opioids must be abandoned as premedicants in patients without pain to not slow gastric emptying and intestinal motility.
One could question the rationale behind the choice of a 12.5% carbohydrate solution by Hausel et al. (7) As discussed in the paper, preoperative carbohydrates stimulate increased plasma insulin. This results in reduced lipolysis and protein degradation. It also results in an improved starting point before the planned surgical trauma with better glycogen liver stores and enhanced myocardial, as well as skeletal muscle function. Lately, it has been shown that IV infusions of amino acids before and during surgery not only improve temperature balance in elective surgical patients but also shorten the length of hospital stay (8–10). Should fluids for preoperative use consist of carbohydrates and electrolytes only? Is there a prolonged gastric emptying if amino acids are added? How about the presence of specific trace elements such as zinc, calcium, and magnesium?
The elegant study by Hausel et al. (7) demonstrates important improvements in variables such as thirst, hunger, and anxiety in adult patients before elective surgery achieved by a special preoperative carbohydrate drink. The study does not only demonstrate improved preoperative patient comfort; it goes beyond. It initiates and stimulates an important new field with a great potential for continued clinical improvement of patient care and postoperative outcome in connection with elective surgical procedures.
References
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