Abstract
Introduction: Fasting overnight NPO (Nulla per os) has been routine before surgery for the past century. The practice was previously designed to reduce the risk of pulmonary aspiration on induction. However this practice has been challenged over the recent years and is changing anaesthetic practices are now more liberal. There are many new concepts aimed at improving patient outcome by regulating metabolic, endocrine, inflammatory and immune responses. This combined with better patient satisfaction and lower anxiety has led to research in this area.
Overnight fasting can induce post operative insulin resistance. Insulin resistance is related to infectious morbidity and increased hospital length of stay (HLOS). Previously this concept was only important in diabetic patients. Surgery places the body under metabolic stress and even a short period of fasting will change the metabolic state of the patient. Indeed physical trauma can cause a triad known as the “diabetes of injury”: insulin resistance, hyperglycaemia and glucose intolerance. Preparation for surgery by maintaining a fasted state and catabolic metabolism may have deleterious consequences for the patient.
Previous studies on elective patients has shown that pre operative carbohydrate loading can reduce insulin resistance and mitigate the inflammatory response by immunomodulation. It has not previously been shown to have an effect in the hip fracture population. This particular group of patients are often elderly and require medical and anaesthetic work up. This delay can mean that the patient is kept fasting for prolonged periods and often overnight.
Methods: With full ethical approval at Connolly Hospital we prospectively randomised all femoral and hip fractures for surgery. We excluded diabetics and pregnant women from the study. A high carbohydrate drink called Nutritia Pre Op was selected. Random serum glucose was taken on admission. Patients were randomised and selected for the trial by hidden ballot. Anaesthetic approval was sought for each case. We compared our standard treatment for hip and femoral fractures of strict NPO prior to surgery versus giving patients the Pre Op drink. Each carton was 200ml and up to 4 were given the night before surgery. In the morning the patients were given another 2 drinks. There was a strict minimum 2 hour NPO period before leaving the ward. Glucose levels were then taken at 1 and 12 hours post operatively to assess whether hyperglycaemia was present. As per laboratory values a normoglycaemia was considered as 4–6mmol/l. Gender, age, type of operation, HLOS, complications and re-admissions were noted.
Results: In total 17 patients were enrolled in the study. Group A had 9 patients and were kept NPO as the control group. Group B had 8 patients enlisted in the Pre Op Drink group. In group A, 6 of 9 (67%) patients had a post operative hyperglycaemia. Average age in group A was 79.6 years with an average HLOS of 15.8 days. 4 patients between them required 8 readmissions over a 3 month post operative period. Group B showed 2 out of 8 (25%) patients had a hyperglycaemia. They had an average age of 69 years with an average HLOS of 11.75 days. 4 patients required 4 readmissions.
Conclusions: Pre Op high carbohydrate drinks significantly decrease post operative hyperglycaemia as per the laboratory ranges. This in turn supports that it decrease insulin resistance by preparing the body for surgery in a fed state. In the same way that one would not prepare for a marathon by fasting 24 hours before hand so the body recognizes that the surgical stress is not best dealt with when in a fasted state. The control group had twice as many readmissions and a longer HLOS. Previous studies show that there is decreased anxiety, thirst and hunger both pre and post operatively. We have shown that this is a safe drink to give and that post operative hyperglycaemia was better controlled.
Correspondence should be addressed to Mr Richard Wallace at Musgrave Park Hospital, 20 Stockman’s Lane, Belfast BT9 7JB, Northern Ireland.
