Endoscopic procedures are increasingly becoming standard of care in a number of diseases in paediatric patients. With escalating complexity of Gastro-endoscopic proce- dures in background of paediatric age gp, disease profile and vulnerable location, ad- ministering sedation/ anaesthesia has become more challenging than ever. Drug in- duced respiratory compromise is a major cause of sedation-associated morbidity in these patient subset, therefore monitoring and vigilance for early signs of systemic com- promise and alveolar hypoventilation is essential. Pulse-oximetry (SpO2) has been established as standard practice to detect hypoxemia as clinical observation alone was insufficient. However, oxygen saturation measured with SpO2 provides only a sur- rogate measure of arterial oxygen saturation (SaO2) and does not completely reflect ventilation. Moreover O2 supplementation during the procedure masks alveolar hy- poventilation by increasing FiO2 and maintaining SpO2. CO2 retention is a hallmark of alveolar hypoventilation and frequent in opioid and propofol based Total Intravenous Anaesthesia(TIVA) techniques. End-tidal carbon dioxide(EtCO2) monitoring has been validated and recommended by American Society of Anesthesiologists and American Society of Gastrointestinal Endoscopy (ASGE) in their guidelines for deep sedation However, during endoscopic procedures EtCO2 monitoring has often found to be difficult and unreliable. Transcutaneous carbon dioxide tension measurement (PtcCO2) combined with conventional monitoring has the potential to become the standard of care in paediatric endoscopic procedures. This Study aims to evaluate the accuracy of Transcutaneous carbon dioxide (PtcCO2) monitoring during paediatric endoscopic proce- dures in predicting hypoventilation over conventional clinical and monitoring techniques.

Methodology 

All paediatric patients between 2-8 years of age (American Society of Anaesthesiologists Class I or II) scheduled for endoscopic procedures will be enrolled for the study. All children will be premedicatied with iv midazolam 75mcg-100mcg/ kg 5-10 mins prior to procedure. Before each procedure the PtcCO2 electrode will be calibrated and baseline PtcCO2 and pulse oximetry (SpO2) will be determined. Physiologic and clinical monitoring will be initiated 5 minutes before administration of sedative agents and continue until at least 10 minutes after final withdrawal of the endoscope. TIVA will be given by an anesthesiologist experienced in handing paediatric patients using a combi- nation of fentanyl midazolam, propofol, and ketamine in a weight-adjusted dose titrating to effect. All patients will be kept spontaneously breathing. For each patient, PtcCO2 and vital parameters (ECG, HR, SPO2, Respiratory Rate, and Pulse Rate) will be recorded every 5 mins and the trend of the vital parameters were closely monitored. Simultane- ously ABG samples will be collected before, at 20 mins and after the procedure for PaCO2 measurements. A respiratory event will be defined as a combination of a 20% change (increase) in PtcCO2 or > 50 mm Hg and SpO2 < 90% for > 1 min. All patients will be on supplemental O2 @ 2L/min by nasal prongs

Sample Size Calculation : The incidence of severe hypoventilation in endoscopic and pediatric sedation is approx 30%.  To find a decrease in incidence to 10% with Î± er- ror of 0.05 and power of 80% a sample size of 152 was calculated.

Statistics : Distribution of the continuous data will be tested with the Komolgorov– Smirnov one-sample test. Continuous variables with a normal distribution will be ex- pressed as mean + standard deviation (SD). Dichotomous data will be expressed as numbers and percentages. Numerical data will be analysed using Student’s t-tests while Nominal variables will be assessed using either the x2 or the Fisher tests. P value <0.05 will be considered statistically significant.

(e) Scope of the project

Our centre provides anaesthesia services to paediatric endoscopic procedures. The challenge of providing anaesthesia in out of OR multifolds in paediatric cases owing to physiology in children which make them more prone for cardiorespiratory events. Presently the standard of care for monitoring in paediatric endoscopic procedures under sedation relies overly on pulse oximetrywhich underestimates hypoventilation. Transcutaneous CO2 tension closely correlates with the PaCO2 values, therefore can be considered an early marker of alveolar hypoventilation. So this study aspires to establish TCO2 as standard of care monitoring in paediatric endoscopic procedures.