Carbohydrate Metabolism—Effects of Preoperative Starvation and Trauma

The effect on intermediary metabolism of open-heart surgery with deep hypothermia and circulatory arrest in infants of less than 10 kilograms body weight. A preliminary study

The effects of hypothermic open-heart surgery with circulatory arrest upon intermediary metabolism and endocrine function in small children are still poorly understood. This report presents data obtained in a preliminary study in which seven children of <10 Kg body weight were investigated during and after such procedures. Frequent blood samples were taken from one day preoperatively to seven days postoperatively for estimation of hormone concentrations (insulin, growth hormone, glucagon, cortisol), and intermediary metabolites (glucose, lactate, pyruvate, alanine, glycerol, and 3- hydroxybutyrate).

Marked hyperglycaemia (34·8 ±3·3 mmol/L) was observed during cardiopulmonary bypass probably as a result of the glucose content of the pump prime. Moderate hyperglycaemia persisted for at least seven days postoperatively. A significant increase in lactate concentrations (p < 0·02) was observed during circulatory arrest and peak concentrations of 6·77 +0.87 mmol/L were measured at the end of the operation. Very high blood lactate concentrations were observed at the end of cardiopulmonary bypass in two patients who subsequently died. Peak insulin concentrations (20·7 ± 5·2 mU/L) were lower than those (30-40 mU/L) reported in adults undergoing similar procedures. Glucagon concentrations were significantly elevated during bypass ( p<0·05) to approximately twice the levels reported in adults. Unlike the other hormones, growth hormone concentrations revealed remarkably uniform change, similar to those reported in 'high responding' adults with peak values of 124 ± 26 mU/L, observed during cardiopulmonary bypass. Cortisol concentrations showed no significant changes throughout the study.

Thus, the response of small infants to these procedures differed both qualitatively and quantitatively from that reported in adults. The results suggest that the nature of the prime fluid may be of major importance in the metabolic consequences of such surgery and that glucose and lactate may be better avoided in the pump prime.

Perioperative management of diabetic patients

Diabetes mellitus is the most common metabolic disease. New classifications have recently been proposed by the American Diabetes Association (ADA) and the World Health Organization (WHO). Type 1 (formerly insulin-dependent diabetes mellitus IDDM) is immune-mediated and leads to absolute insulin deficiency. Type 2 diabetes (formerly non-insulin-dependent diabetes mellitus [NIDDM]) is a disease of adult onset and is associated with insulin resistance. Type 3 corresponds to a wide range of specific types of diabetes, including various genetic defects of beta-cell function and insulin action, diseases of exocrine pancreas, endocrinopathies, and drug-induced diabetes. Type 4 is gestational diabetes (Table 1). Diabetics undergoing surgery have increased mortality, and type 1 diabetics are particularly at risk of postoperative complications. Wound complications are increased in diabetics, and healing is severely impaired when glycemic control is poor. However, with the use of modern management plans, the major outcome measures of surgery are comparable in diabetic and nondiabetic patients. Successful management of surgery in diabetic patients requires simple and safe protocols, which are fully understood by all staff and a close liaison among the surgeons, diabetes care team, and anesthetists. There is no consensus on the optimal metabolic management of the diabetic patient during surgery. Several surveys have highlighted the inconsistency with which surgical problems are managed in diabetic patients. The aim of this article is to provide protocols to achieve sensible and practical glycemic control in diabetic patients undergoing surgery.

Diabetologic in-service education for health professionals from non-diabetological departments

In order to test whether or not an in-service requalification course on diabetes care for health professionals (HP) of nondiabetological departments can enhance their level of knowledge about diabetes and the quality of care for diabetic inpatients admitted for reasons other than diabetes, we carried out a requalification course involving 171 HP (161 nurses and 10 midwives) from nondiabetological departments of our hospital. Areas of intervention were: general knowledge of diabetes (GKD), bedside monitoring of blood glucose (BMG), insulin preparation and administration (IPA), diagnosis and treatment of hypoglycemic crises (DTH), and hospitalization-related problems (HRP). HP, divided into groups of about 20 each, completed a basal evaluation by means of a 25-item multiple choice questionnaire, and then attended six separate educative sessions, each of focusing on one topic, consisting of a theory lesson and an interactive exercise of equivalent length. At the end of the course, HP were re-evaluated with the same questionnaire, and their skills in BMG, IPA and DTH were tested by means of specific operational checklists, which divided each complex operation into a sequence of single operations, and then compared them with those of a control group of untrained colleagues (CG). The global knowledge of diabetes after the courses significantly improved, as gathered from the percentages of correct answers in each questionnaire (61.82% +/- 23.64% vs 31.18% +/- 20.00%; P < 0.001); separate analysis of different areas evidenced improvements in GKD (72.28% +/- 12.47% vs 31.46% +/- 20.56%; P < 0.01), BMG (68.77% +/- 15.75% vs 37.50% +/- 27.75%; P < 0.01), IPA (72.02% +/- 11.72% vs 33.45% +/- 21.22%; P < 0.05), and DTH (90.76% +/- 6.86% vs 49.82% +/- 26.68%; P < 0.05), but not in HRP. Professional skills profiles of HP, evaluated by measuring the number of errors done performing each task, were significantly (P < 0.001) better than those of CG, for BMG (1.09 +/- 0.73 vs 4.91 +/- 2.01), IPA (2.36 +/- 1.64 vs 5.64 +/- 2.25), and DHT (1.27 +/- 0.94 vs 3.82 +/- 1.12). Linear regression showed a significant (P < 0.001) correlation of skills and knowledge after the course for BMG (r2 = .49), IPA (r2 = .53), and DTH (r2 = .61). Positive although nonspecific indicators of outcomes of the course were the increase (of about 100%) of requests to our metabolic unit for diabetological consultations from other departments as well as the mentioning of diabetes in the diagnosis of discharge, and the 20% increase in the consumption of sticks for BMG. The course produced a significant improvement of knowledge and skills on specific diabetological items among participants.

The metabolic load of stored blood. Implications for major transfusions in infants

Plasma electrolyte, intermediary metabolite, and hormone concentrations were measured in samples of 110 units of citrate phosphate dextrose blood being used for clinical transfusions. The most important changes from the physiological range were in sodium, potassium, glucose, and lactate concentrations. Mean sodium concentrations fell from 170 mmol/l at the beginning of storage to 156 mmol/l at the end and mean potassium concentrations rose from 7 mmol/l to 25 mmol/l. Glucose had a mean concentration of 20 mmol/l at the beginning of storage and had only fallen to 15 mmol/l at the end. Mean lactate concentrations increased from 7 mmol/l at the beginning of storage to 25 mmol/l at the end. Many samples had cortisol, insulin, and growth hormone concentrations within the physiological range. Citrate phosphate dextrose blood contains a large substrate load that changes during storage and that should be taken into account when infants are transfused large volumes of blood. The strong correlation coefficients with duration of storage for sodium, potassium, and lactate (-0.71, 0.91, and 0.90, respectively) indicate that concentrations of these substrates can be predicted within a narrow range if the duration of blood storage is known.

The energy expenditure of the mechanically ventilated critically ill patient. An analysis

This study characterizes the pattern of caloric expenditure of a group of 19 mechanically ventilated critically ill patients after surgery. Continuous measurements of metabolic rate were used to examine the total energy expended over an eight-hour period (10 AM to 6 PM) on 21 occassions. This allowed for determination of the energy expended during activity, rest, and sleep. The patients were observed to be resting, defined as lying motionless with eyes open and responsive to surrounding events, for 44 +/- 4 percent (SE) of the studied period. Sleeping, a state where the patient was not aroused by surrounding events, was observed for 17 +/- 3 percent of the studied period. Total energy expenditure was 4.8 +/- 1.8 percent greater than resting energy expenditure (REE). The REE was 13.1 +/- 2.3 percent above sleeping energy expenditure (awakeness factor), while activity energy expenditure was 17.1 +/- 2.9 percent above REE (activity factor). The respiratory quotient (RQ) during activity in the 15 patients receiving infusions of physiologic saline solution or 5 percent dextrose solution was significantly less (p less than 0.02) than the RQ during rest. This appears to be due to increased fat oxidation during activity.