Sherif Awad

A meta-analysis of randomised controlled trials on preoperative oral carbohydrate treatment in elective surgery

BACKGROUND & AIMS Whilst preoperative carbohydrate treatment (PCT) results in beneficial physiological effects, the effects on postoperative clinical outcomes remain unclear and were studied in this meta-analysis. METHODS Prospective studies that randomised adult non-diabetic patients to either PCT (≥50 g oral carbohydrates 2-4 h pre-anaesthesia) or control (fasted/placebo) were included. The primary outcome was length of hospital stay. Secondary outcomes included development of postoperative insulin resistance, complications, nausea and vomiting. Methodological quality was assessed using GRADEpro® software. RESULTS Twenty-one randomised studies of 1685 patients (733 PCT: 952 control) were included. No overall difference in length of stay was noted for analysis of all studies or subgroups of patients undergoing surgery with an expected hospital stay ≤2 days or orthopaedic procedures. However, patients undergoing major abdominal surgery following PCT had reduced length of stay [mean difference, 95% confidence interval: -1.08 (-1.87 to -0.29); I² = 60%, p = 0.007]. PCT reduced postoperative insulin resistance with no effects on in-hospital complications over control (risk ratio, 95% confidence interval, 0.88 (0.50-1.53), I² = 41%; p = 0.640). There was significant heterogeneity amongst studies and, therefore, quality of evidence was low to moderate. CONCLUSIONS PCT may be associated with reduced length of stay in patients undergoing major abdominal surgery, however, the included studies were of low to moderate quality.

Comparison of lateral thermal spread using monopolar and bipolar diathermy, the Harmonic Scalpel and the Ligasure.

Electrosurgery for dissection and haemostasis should be associated with minimal thermal spread to surrounding tissues. This study investigated lateral thermal spread following ex vivo application of four commonly utilized instruments.

Short-term starvation and mitochondrial dysfunction – A possible mechanism leading to postoperative insulin resistance

BACKGROUND Preoperative starvation results in the development of insulin resistance. Measures to attenuate the development of insulin resistance, such as preoperative carbohydrate loading, lead to clinical benefits. However, the mechanisms that underlie the development of insulin resistance during starvation and its attenuation by preoperative carbohydrate loading remain to be defined. Insulin resistance associated with type 2 diabetes and ageing has been linked to mitochondrial dysfunction. The metabolic consequences of preoperative starvation and carbohydrate loading and mechanisms linking insulin resistance to impaired mitochondrial function are discussed. METHODS Searches of the Medline and Science Citation Index databases were performed using various key words in combinations with the Boolean operators AND, OR and NOT. Key journals, nutrition and metabolism textbooks and the reference lists of key articles were also hand searched. RESULTS Animal studies have shown that short-term energy deprivation decreases mitochondrial ATP synthesis capacity and complex activity, and increases oxidative injury. Furthermore, evidence from human studies suggests that the development of insulin resistance during starvation may be linked to impaired mitochondrial function. CONCLUSIONS There is evidence from animal studies that short-term starvation causes mitochondrial dysfunction. Future studies should investigate whether mitochondrial dysfunction underlies the development of insulin resistance in patients undergoing elective surgery.

Cellular mechanisms underlying the protective effects of preoperative feeding: a randomized study investigating muscle and liver glycogen content, mitochondrial function, gene and protein expression.

Objective:To investigate the effects of preoperative feeding with a carbohydrate-based drink that also contained glutamine and antioxidants (oral nutritional supplement [ONS], Fresenuis Kabi, Germany) on glycogen reserves, mitochondrial function, and the expression of key metabolic genes and proteins. Summary Background Data:Preoperative carbohydrate loading attenuates the decline in postoperative insulin sensitivity but the cellular mechanisms underlying this remain unclear. Methods:Two groups of 20 patients undergoing laparoscopic cholecystectomy participated in this randomized placebo-controlled double-blind study. Patients received either 600 mL of ONS or placebo the evening before surgery, and again 300 mL 3 to 4 hours before anesthesia. A 300-mL aliquot of ONS contained 50 g of carbohydrate, 15 g of glutamine and antioxidants. Blood was sampled before ingestion of the evening drink, after induction of anesthesia, and on postoperative day 1 for measurement of concentrations of glucose, glutamine, and antioxidants. Rectus abdominis muscle and liver biopsies were performed intraoperatively to determine glycogen and glutamine concentrations, mitochondrial function, pyruvate dehydrogenase kinase (PDK4), forkhead transcription factor 1 (FOXO1), and metallothionein 1A (Mt1A) expression. Results:There were no drink-related complications. ONS ingestion led to increased intraoperative liver glycogen reserves (44%, P < 0.001) and plasma glutamine and antioxidant concentrations, the latter 2 remaining elevated up to the first postoperative day. Muscle PDK4 mRNA, PDK4 protein expression, and Mt1A mRNA expression were 4-fold (P < 0.001), 44% (P < 0.05), and 1.5-fold (P < 0.001), respectively, lower in the ONS group. There were no differences in FOXO1 mRNA and protein expression. Conclusions:The changes in muscle PDK4 may explain the mechanism by which preoperative feeding with carbohydrate-based drinks attenuates the development of postoperative insulin resistance.

Mucins and CD56 as markers of tumour invasion and prognosis in periampullary cancer

This study investigated the association of mucins and cluster of differentiation (CD) 56 with vascular and perineural invasion and survival in patients with periampullary cancer.

Metabolic conditioning to attenuate the adverse effects of perioperative fasting and improve patient outcomes.

Purpose of reviewTo review recent articles, published between October 2009 and September 2011, that examined the adverse metabolic consequences of perioperative fasting and interventions that may be utilized to minimize these effects. Recent findingsFasting induces metabolic stress and insulin resistance consequent upon effects on cellular mitochondria, gene and protein expression. Development of perioperative insulin resistance leads to increased postoperative morbidity and mortality. Preoperative carbohydrate loading attenuates insulin resistance via effects on cellular gene and protein expression, but its effects on clinical outcomes remain unclear. Perioperative arginine-supplemented diets were shown to be associated with significant reductions in infectious complications and length of hospital stay in patients undergoing elective surgery. Perioperative metabolic conditioning using glutamine and L-carnitine may be used to modulate insulin sensitivity but further studies need to determine whether these interventions result in clinical benefit. Finally, energy and protein provision to critically ill patients remains inadequate and is hampered by a number of factors including reliance on inaccurate means of estimating energy expenditure and enteral feed tolerance, conflicting data on the effects of energy deficit on clinical outcomes, and poor methodological quality of studies of perioperative nutritional interventions. SummaryNumerous perioperative interventions are available, which if utilized should help attenuate the adverse effects of perioperative fasting and lead to improved patient outcomes.

Knowledge and attitudes of surgical trainees towards nutritional support: Food for thought☆

BACKGROUND & AIMS Up to 40% of patients admitted to UK hospitals are malnourished and appropriate nutritional intervention can improve outcomes. We investigated the knowledge and attitudes of UK surgical trainees towards nutritional support and compared their responses with dieticians. METHODS Trainee surgeons and qualified dieticians were asked to complete a multiple choice question test derived from topics relating to nutritional support, followed by a questionnaire on their attitudes towards nutrition. Participants were unaware that they would be tested. RESULTS The test was administered to 63 doctors and 25 dieticians. There were 19 newly qualified doctors (foundation year 1 [FY(1)]), 21 junior surgeons (speciality-training years 1 and 2 [ST(1-2)]) and 23 senior surgeons (speciality-training years 3 and above [ST(3+)]). Mean [SE] test scores were lower for doctors compared to dieticians (14.0 [0.64] versus 26.4 [0.22], p<0.001). The respective test scores for FY(1), ST(1-2), ST(3+) doctors were 9.8 [0.78], 14.3 [1.10] and 17.3 [0.76]. Only 47% of doctors felt they had adequate knowledge of this subject and 65% stated that they regularly made decisions on nutritional support. Furthermore, only 25% stated they could calculate daily energy and nutritional requirements. CONCLUSION Despite making decisions related to nutritional support regularly, surgical doctors in the UK demonstrated less knowledge of the fundamental principles of nutritional support than dieticians.

Fluid and electrolyte balance: The impact of goal directed teaching

BACKGROUND & AIMS We aimed to determine if a structured workshop on fluid and electrolyte balance for junior surgical trainees led to an improvement in knowledge on the subject and to evaluate the perceived helpfulness of such a workshop. METHODS Surgical trainees attended an interactive lecture-based workshop on fluid and electrolyte balance. Participants had online access to the presentation prior to the training event. They completed a multiple choice question (MCQ) test, derived from topics covered in the presentation, prior to the lecture. The MCQ test was repeated after the lecture to assess retention and application of knowledge. Participants were unaware that they would be tested and provided written feedback on their perceptions of the session. RESULTS Thirty-seven trainees from speciality training years 1 and 2 participated in the workshop. There was a significant improvement in mean test scores after the lecture when compared with pre-lecture scores (24.6/30 vs. 19.7/30, p<0.001). Trainees felt the topic and event were relevant to everyday practice (mean score 4.9/5) and that it would improve their clinical skills (4.5/5). CONCLUSIONS The provision of a dedicated fluid and electrolyte physiology interactive workshop to postgraduate trainees is a successful way of tackling current inadequacies in training.

What's new in perioperative nutritional support?

Purpose of review To highlight recent developments in the field of perioperative nutritional support by reviewing clinically pertinent English language articles from October 2008 to December 2010, that examined the effects of malnutrition on surgical outcomes, optimizing metabolic function and nutritional status preoperatively and postoperatively. Recent findings Recognition of patients with or at risk of malnutrition remains poor despite the availability of numerous clinical aids and clear evidence of the adverse effects of poor nutritional status on postoperative clinical outcomes. Unfortunately, poor design and significant heterogeneity remain amongst many studies of nutritional interventions in surgical patients. Patients undergoing elective surgery should be managed within a multimodal pathway that includes evidence-based interventions to optimize nutritional status perioperatively. The aforementioned should include screening patients to identify those at high nutritional risk, perioperative immuno-nutrition, minimizing ‘metabolic stress’ and insulin resistance by preoperative conditioning with carbohydrate-based drinks, glutamine supplementation, minimal access surgery and enhanced recovery protocols. Finally gut-specific nutrients and prokinetics should be utilized to improve enteral feed tolerance thereby permitting early enteral feeding. Summary An evidence-based multimodal pathway that includes interventions to optimize nutritional status may improve outcomes following elective surgery.

Effects of an intraoperative infusion of 4% succinylated gelatine (Gelofusine®) and 6% hydroxyethyl starch (Voluven®) on blood volume

BACKGROUND This study aims to study changes in blood volume after 1 litre infusions of Gelofusine(®) [4% succinylated gelatine in 0.7% saline, weight-average molecular weight (MWw) 30 kDa] and Voluven(®) (6% hydroxyethyl starch in 0.9% saline, MWw 130 kDa) in the presence of increased capillary permeability. METHODS In this randomized double-blind study, adults undergoing laparoscopic cholecystectomy received 1 litre of Gelofusine(®) (n=12) or Voluven(®) (n=13) over 1 h at the induction of anaesthesia. No other fluids were given. Haematocrit, serum electrolytes, and osmolality were measured before infusion and hourly thereafter for 4 h. Changes in blood volume were calculated from changes in haematocrit. The urinary albumin:creatinine ratio (ACR) was measured before and after operation. RESULTS Baseline parameters before the two infusions were similar (P>0.050). The urinary ACR increased significantly after operation after Gelofusine(®) (P=0.011) and Voluven(®) (P=0.002), indicating increased capillary permeability. Voluven(®) produced a greater increase in serum chloride concentration (P=0.028) and a larger decrease in strong ion difference (P=0.009) than Gelofusine(®). There were no significant differences in changes in haematocrit (P=0.523) and blood volume (P=0.404) over the study period when the two infusions were compared, nor were there any differences in serum sodium, potassium, bicarbonate, and albumin concentrations (P>0.050). Urine output, sodium concentration, and osmolality were similar after the two infusions (P>0.050). CONCLUSIONS The blood volume-expanding effects of the two colloids were not significantly different, despite the increase in postoperative urinary ACR and the 100 kDa difference in MWw.