i THE EFFECT OF PREOPERATIVE APPLE JUICE ON THE PREVALENCE OF HYPOGLYCAEMIA IN PAEDIATRIC PATIENTS CLOVER-ANN LEE A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, in partial fulfillment of the requirements for the degree of Master of Medicine in Anaesthesia Johannesburg, 2012 ii DECLARATION I, Clover-Ann Patricia Lee, declare that this research report is my own work. It is being submitted for the Degree of Master of Medicine at the University of the Witwatersrand, Johannesburg. It has not been submitted before for any degree or examination at this or any other university. Signature Signed at: University of the Witwatersrand, Johannesburg On this date: 08.05.2012 iii PRESENTATIONS ARISING FROM THIS PROJECT Poster Presentations: “Clear apple juice on the morning of surgery reduces the prevalence of hypoglycaemia in children” presented at: 1. Paediatric Anesthesia Congress of South Africa, Johannesburg, November 2010 2. Society of Pediatric Anesthesia Annual Meeting, San Diego, USA, March 2011. iv ABSTRACT Background: Children have historically been fasted for prolonged periods preoperatively to reduce the volume and acidity of their gastric contents and thus the risk of regurgitation and pulmonary aspiration. Evidence shows that this risk is not increased by following the current recommended fasting guidelines, and that prolonged fasting may be detrimental to children, who may present with hunger, thirst, depleted intravascular volume, metabolic acidosis and hypoglycaemia. A recent study at Charlotte Maxeke Johannesburg Academic Hospital showed a 18.5% prevalence of biochemical hypoglycaemia, defined as a blood glucose concentration of less than 3.5 mmol/l, in children from one to five years of age presenting for elective surgery. Aims: The aims of this study were to document the prevalence of biochemical hypoglycaemia in children from the ages of one to five years who were given apple juice to drink at least two hours preoperatively, and to compare these results to a historical control group. Methods: A prospective, contextual comparative study design was used. Approval was obtained from the University of the Witwatersrandʼs Human Ethics Committee and other relevant authorities. The groups were matched for age and weight. Consent was obtained from the guardians of all children who met the inclusion criteria before being enrolled in the study. A standard 200 ml carton of commercially available apple juice was offered to each participant. The volume and time of the juice consumed was documented, along with relevant demographic data. Inhalational induction of anaesthesia v proceeded a minimum of two hours later, and a venous glucose concentration was measured. Results: The prevalence of biochemical hypoglycaemia was statistically significantly reduced in the intervention group (p = 0.0163), eliminating the effect of prolonged preoperative fasting. Conclusion: The consumption of clear apple juice on the morning of surgery is a safe, inexpensive, effective way to reduce the prevalence of hypoglycaemia in children presenting for elective surgery. vi ACKNOWLEDGEMENTS My thanks go to the following people: To my parents, whose sacrifices made my education possible. To my supervisors, Juan Scribante and Helen Perrie, for their support, guidance, and patience. To the “Jʼs”: to Jenny King, for being the teacher and role model who made me want to be an anaesthetist; to Jacinta Shung for her mentorship and encouragement; and to Jenny Thomas, for providing an example to strive for. To Hennie Gerber, for his statistical input and patient explanations. To Mike Blackburn and Des Klein, IT wizards extraordinaire. To the paediatric surgical and nursing team, especially Andrew Grieve and Lesley Pieterse, who let me feed their patients juice and didnʼt complain about any changes to their lists. vii TABLE OF CONTENTS DECLARATION ii ABSTRACT PRESENTATIONS ARISING FROM THIS PROJECT iii v ACKNOWLEDGEMENTS vi TABLE OF CONTENTS vii LIST OF FIGURES x LIST OF TABLES x CHAPTER ONE OVERVIEW OF THE STUDY 1.1 Introduction 1 1.2 Background to the study 1 1.3 Problem statement 3 1.4 The aim of the study 4 1.5 Objectives of the study 4 1.6 Definitions used in the study 4 1.7 Demarcation of the study field 5 1.8 Ethical considerations 5 1.9 Research methodology 6 1.9.1 Research design 6 1.9.2 Study population and sample size 6 1.9.3 Sample method 6 1.9.4 Criteria for the study 6 1.9.5 Methodology 7 1.9.6 Data analysis 8 1.10 Significance of the study 8 1.11 Validity and reliability 9 1.12 Potential limitations 9 1.13 Project outine 10 1.14 Summary 10 CHAPTER TWO LITERATURE REVIEW AND BACKGROUND 2.1 Introduction 12 2.2 History of the “nil per os from midnight” order 12 2.3 Physiology of gastric emptying 13 2.3.1 Liquids 15 2.3.2 Milk 15 2.3.3 Solids 17 viii 2.4 Pathophysiology of regurgitation 18 2.5 Pulmonary aspiration and pneumonitis 20 2.6 The incidence of pulmonary aspiration in children 20 2.7 Physiology of fasting and glucose control 21 2.8 Fasting outcomes 23 2.8.1 Thirst 23 2.8.2 Hunger 23 2.8.3 Hypotension 24 2.8.4 Metabolic acidosis 24 2.8.5 Cognitive function 24 2.9 Hypoglycaemia 24 2.9.1 Definition 24 2.9.2 Pathophysiology 26 2.9.3 Signs and symptoms 27 2.9.4 The brain and hypoglycaemia 28 2.9.5 Perioperative hypoglycaemia in children 30 2.10 Summary 41 CHAPTER THREE RESEARCH DESIGN AND METHODS 3.1 Introduction 42 3.2 Problem statement 42 3.3 The aim of the study 42 3.4 Objectives of the study 43 3.5 Ethical considerations 43 3.6 Research design 44 3.6.1 Sample size 45 3.6.2 Sample method 45 3.6.3 Inclusion and exclusion criteria 46 3.7 Methodology 47 3.7.1 Quality assurance 47 3.8 Data analysis 49 3.9 Summary 51 CHAPTER FOUR DATA ANALYSIS AND DISCUSSION OF RESULTS 4.1 Introduction 52 4.2 Results 52 4.2.1 Demographic data 52 4.2.2 The prevalence of hypoglycaemia at induction of anaesthesia 54 ix 4.2.3 Comparison of results with the control group 57 4.3 Discussion 63 4.4 Conclusion 65 4.5 Summary 66 CHAPTER FIVE SUMMARY, LIMITATIONS, RECOMMENDATIONS AND CONCLUSIONS 5.1 Introduction 67 5.2 Summary of the study 67 5.2.1 Aim of the study 67 5.2.2 Objectives of the study 67 5.2.3 Summary of the methodology used in the study 68 5.3 Main findings of the study 69 5.4 Limitations of the study 70 5.5 Recommendations from the study 71 5.5.1 Clinical practice 71 5.5.2 Further research 71 5.6 Conclusion 72 REFERENCES 73 APPENDICES Appendix A Permission from Postgraduate Committee 84 Appendix B Permission from Ethics Committee 85 Appendix C Patient information letter 86 Appendix D Consent form 87 Appendix E Data collection form 88 x LIST OF FIGURES Figure 4.1 Ages of children studied 53 Figure 4.2 Distribution of data for weight 57 Figure 4.3 Prediction profiler for the control group 62 Figure 4.4 Prediction profiler for the treatment group 62 Figure 4.5 Bivariate fit of glucose concentration by fasting duration 63 LIST OF TABLES Table 2.1 Perioperative hypoglycaemia in children 35 Table 4.1 Demographic data of patients studied 54 Table 4.2 Blood glucose values at induction of anaesthesia 55 Table 4.3 Children with biochemical hypoglycaemia at anaesthetic induction 56 Table 4.4 Shapiro-Wilk test to test for normal distribution of data 58 Table 4.5 Table of means and standard deviations 58 Table 4.6 Contingency table to test for an association between blood glucose level and receiving apple juice on the morning of surgery 59 xi