1 Is inhalational induction justifiable in paediatric emergencies?Richard Craig Alder Hey Children’s Hospital

2 “The beginning of wisdom is the definition of terms.”–Socrates

3 “If you wish to converse with me,” said Voltaire, “define your terms.”–Will Durant The story of philosophy Chapter 2 part 3: the foundation of logic, page 59

4 Emergencies A B C Intervention required within 24 hours

5 Anatomical Airway ObstructionPrinciple: maintain spontaneous ventilation until the airway is secure Rationale: to retain some muscle tone in the upper airway and allow time for laryngoscopy and intubation Why not give a muscle relaxant? - to avoid the scenario where a muscle relaxant has been given, bag-mask ventilation proves difficult or impossible, the child becomes hypoxaemic, and cannot be intubated - CICO The management of difficult intubation in children. Paediatric Anesthesia 2009; 19 (Suppl. 1): RM Walker and J Ellwood.

6 Anatomical Airway ObstructionInhalational induction still popular in paediatrics NAP 4 census report - management of the predicted difficult airway in children: Inhalational induction - 63% Intravenous induction - 37% Awake intubation - 0%

7 Anatomical Airway ObstructionCanadian paediatric anesthesiologists prefer inhalational anesthesia to manage difficult airways: a survey Canadian Journal of Anesthesia 2005; 52:3 pp Peter Brooks et al. 6 scenarios - web-based survey 63 responses from 136 invitations- experienced paediatric anaesthetists 2 scenarios - emergencies with a compromised airway 2 year old child with potential epiglottis needing emergency endotracheal intubation - 95% of respondents chose to keep the patient breathing spontaneously and 97% would use an inhalational agent to do this.

8 Anatomical Airway ObstructionRigid bronchoscopy for foreign body removal: anaesthesia and ventilation Pediatric Anesthesia : pp84 -89 PT Farrell “in an emergency situation or with a distressed infant, establishing iv access immediately after inhalation induction is acceptable” “spontaneous ventilation must be maintained until it is certain that the child can still be ventilated under anaesthesia” “most experienced anaesthesiologists prefer inhalational rather than intravenous induction”

9 Anatomical Airway ObstructionA child with a difficult airway: what do I do next? Current Opinion in Anesthesiology 2012; 25(3): T Engelhardt and M Weiss “the recent NAP 4 audit suggests that spontaneously breathing adult patients who lost the airway do not recover rapidly. Full recovery of a child with lower oxygen reserves is even more unlikely and as yet not reported in the literature.”

10 Anatomical Airway ObstructionNAP 4 report: Chapter 13 management of the CICV situation, page 113

11 Anatomical Airway ObstructionDAS 2015 guidelines for the management of the unanticipated difficult intubation in adults Plan C - the final attempt at face-mask ventilation If face-mask ventilation is impossible - paralyze ensuring full paralysis offers a final chance of rescuing the airway without recourse to Plan D airway rescue via the front of neck should not be attempted without complete neuromuscular block

12 Anatomical Airway ObstructionCannot ventilate - paralyze! Pediatric Anesthesia M Weiss and T Engelhardt Treat functional airway obstruction Functional airway obstruction is the leading cause of difficult or failed facemask ventilation “a deeply anesthetized, hypoxic brain is unlikely to restart spontaneous breathing and establish airway patency. There is no way back…”

13 Anatomical Airway ObstructionAPA/DAS guidelines for the management of the unanticipated difficult airway in paediatric practice Pediatric Anesthesia AE Black et al. “the CICV scenario is considered in the context of the paralysed child” “sugammadex should not be given to reverse rocuronium or vecuronium if the child is rapidly deteriorating with decreasing SpO2 and haemodynamic compromise”

14 Functional Airway ObstructionWhich port in a Storm? Use of suxamethonium without intravenous access for severe laryngospasm RWM Walker and R Sutton Anesthesia : Suxamethonium 4 mg/kg into the deltoid muscle - should work within 1 min

15 Anterior mediastinal mass

16 Anterior mediastinal massAnesthetic management of children with an anterior mediastinal mass Journal of Clinical Anesthesia : PA Stricker, HG Gurnaney, and RS Litman Spontaneous ventilation was maintained in 21 of 46 cases 26 patients had signs and symptoms suggestive of cardiopulmonary compromise as well as radiologic evidence of respiratory or cardiovascular compression - muscle relaxant was avoided in 18 of these cases - 17 of these case received iv sedation with spontaneous ventilation and a natural airway, often in the Semi-Fowler’s position - one complication in the 8 patients who received muscle relaxant and IPPV - bronchospasm that resolved with administration of a bronchodilator

17 Anterior mediastinal massThe anaesthetic management of children with anterior mediastinal mass Anaesthesia 2008, 63: HA Hack, NB Wright, and RF Wynn 53 anaesthetic charts available for inspection 25/53 - inhalational induction; 2 of these in the sitting position, 1in the lateral position. 28/53 - iv induction in the supine position 18/53 - maintained spontaneous ventilation; FM, LMA, ETT. 35/53 - IPPV no significant difference in the tracheal cross-sectional area

18 Risk of aspiration NAP 4 - aspiration was the main cause of adverse outcome at induction NAP 4 - aspiration was the cause of 50% of anaesthesia deaths and 53% of outcomes of death or brain damage Recommendation: On 􏰀balance, rapid sequence induction should continue to 􏰀be taught as a standard technique for protection of the airway. Further focused research might usefully 􏰀be performed to explore its efficacy, limitations and also explore the consequences of its omission. Chapter 19, page 163

19 Risk of Aspiration Pulmonary Aspiration in pediatric anesthetic practice in the UK: a prospective survey of specialist pediatric centres over a one year period Pediatric Anesthesia : Robert W.M. Walker 1 year, 11 paediatric centres, denominator 2 per cases for elective work 2.2 per cases for non-elective work no deaths 5 cases with serious morbidity - needing PICU

20 Risk of Aspiration Pulmonary Aspiration in pediatric anesthetic practice in the UK: a prospective survey of specialist pediatric centres over a one year period Pediatric Anesthesia : Robert W.M. Walker 12 / 24 cases of pulmonary aspiration of gastric contents occurred at induction 7 /12 cases of pulmonary aspiration of gastric contents at induction = iv induction 5 / 12 cases of pulmonary aspiration of gastric contents at induction = inhalational induction 8 /12 cases of pulmonary aspiration of gastric contents at induction = elective cases (3 had inhalational induction) 4 /12 cases of pulmonary aspiration of gastric contents at induction = non-elective (2 had inhalational induction)

21 Risk of aspiration Perioperative pulmonary aspiration in infants and children Anesthesiology 1999; 90: MA Warner et al. 3.8 per cases 2 per for elective cases 25 per for emergency cases consecutive anaesthetics no deaths

22 Risk of aspiration Pulmonary aspiration in pediatric patients during general anaesthesia: incidence and outcomes Journal of Clinical Anesthesia 1998; 10: LM Borland et al. 10.2 per cases anaesthetics no deaths

23 Risk of aspiration Pulmonary aspiration under GA: a 13-year audit in a tertiary pediatric unit Z Tan and SY Lee Pediatric Anesthesia 2016, 26: 22 cases of pulmonary aspiration / general anaesthetic 2.15 per 12/ 22 - iv induction 10/ 22 - inhalational induction iv vs inhalational induction odds ratio (95%CI ) emergency surgery vs elective surgery odds ratio (95% confidence interval )

24 Risk of aspiration minimise the gastric volume - fasting, prokinetics, and NG tube; use ultrasound to check increase the pH of gastric contents - sodium citrate, ranitidine, PPI RSI - cricoid pressure; apnoeic inducton Effects of different combinations of H2 receptor antagonists with gastrokinetic drugs on gastric fluid pH and volume in children - a comparative study Int j Pharmacol Ther 1997; 35: Kulkarni PN, Batra YK, Wig J

25 Risk of aspiration Avoid:Decreasing intrathoracic pressure: airway obstruction, hiccup Elevating intra-abdominal pressure: laryngoscopy during light anaesthesia, coughing or straining during induction or intubation, inflating the stomach during bag-mask ventilation Oesophageal intubation Haste Hypoxaemia

26 Risk of aspiration - apnoeic induction?Controlled rapid sequence induction and intubation - an analysis of 1001 children D Neuhaus, A Schmitz, A Gerber, et al. Pediatric Anesthesia 2013, 23: gentle face-mask ventilation prior to intubation, avoidance of cricoid pressure, non-depolarising neuromuscular blocking agent moderate hypoxaemia (SpO %) in 0.5%; n = 5 severe hypoxaemia (SpO2 < 80%) in 0.3%; n =3 1 episode of regurgitation without aspiration

27 Is cricoid pressure harmful?airway occlusion distorted anatomy failed intubation difficult or impossible face-mask ventilation relaxation of the lower oesophageal sphincter a trigger for vomiting? may provoke bucking or straining interferes with a smooth induction Cricoid pressure: apply - but be ready to release Anaesthesia 2016, 71, J Turnbull, A Patel, V Athanassoglou, JJ Pandit

28 Cricoid pressure Aspiration and regurgitation prophylaxis in paediatric anaesthesia Pediatric Anesthesia 2001; 11: Engelhardt T, Strachen L, Johnston G “Up to 50% of paediatric anaesthetists would not use cricoid pressure in the “full stomach” situation” Do you routinely employ the following prior to anaesthesia in all children regardless of risk factors? 42% (37 / 88 replies) would routinely apply cricoid pressure in children < 1year of age having emergency surgery 49% (43 / 88 replies) would routinely apply cricoid pressure in children aged years having emergency surgery

29 Cricoid Pressure Effect of cricoid force on airway calibre in children: a bronchoscopic study British Journal of Anaesthesia 2010; 104: 71-74 Walker RWM, Ravi R, Haylett K 5N = the force required to cause 50% occlusion of the subglottic airway with the application of cricoid pressure in infants

30 “Rapid sequence induction has no use in paediatric anesthesia”Pediatric Anesthesia 2015; 25: pp 5-8 Thomas Englehardt “Regurgitation and vomiting with aspiration are processes elicited by direct laryngoscopy under light anaesthesia and incomplete muscle paralysis” Advocates mask ventilation with pressures not exceeding cmH2O following induction and before intubation in paediatric RSI induction of sufficiently deep anaesthesia avoid cricoid pressure confirm complete muscle paralysis before laryngoscopy

31 Is cricoid pressure effectiveNo RCTs Absence of evidence is not evidence of absence Argument from ignorance - a proposition is true because it has not yet be proved false Aspiration does occur despite the application of CP Anatomy - the oesophagus is postero-lateral to the cricoid ring in 50% of people; lateral displacement increases with CP, but it is the post-cricoid hypo pharynx that is compressed and occluded - MRI, videolaryngosocpy, attempts to pass 4mm NG tube

32

33 Gastric Ultrasound Gastric antrumRight lateral decubitus position – only the RLD antrum CSA and age were shown to be independent predictors of endoscopically suctioned gastric volume Sagittal or right para-sagittal Between the left lobe of the liver and the pancreas at the level of the aorta and superior mesenteric artery or inferior vena cava Ultrasound assessment of gastric volume in the fasted pediatric patient undergoing upper gastrointestinal endoscopy: development of a predictive model using endoscopically suctioned volumes Pediatric anesthesia 2015; 25: Adam O. Spencer, Anrew M Walker, Alfred K. Yeung, et al.

34 Gastric Ultrasound Qualitative assessmentGrade 0: no fluid visible in the antrum in either the supine or RLD position Grade 1: antral fluid visible in the RLD position but not in the supine position Grade2: antral fluid visible in both the supine and RLD position Quantitative assessment Antral cross-sectional area in the RLD position Volume = (3.5 x RLD CSA) + (0.127 x age in months) Ultrasound assessment of gastric volume in the fasted pediatric patient undergoing upper gastrointestinal endoscopy: development of a predictive model using endoscopically suctioned volumes Pediatric anesthesia 2015; 25: Adam O. Spencer, Anrew M Walker, Alfred K. Yeung, et al.

35 Gastric ultrasound in babies with hypertrophic pyloric stenosis undergoing pyloromyotomy34 infants Ultrasound of gastric antrum in the right lateral decubitus position before and after aspiration of gastric contents through 10Fr gastric tube Ultrasound examination before aspiration failed in 3/34 - gas in the stomach or infant agitation No failed examinations after gastric aspiration 9/31 empty stomach on first ultrasound 22/31 full stomach on first ultrasound The aspirated gastric volume correlates with the antral cross sectional area measured in the RLD – Pearson correlation coefficient 0.83 (95% CI ; p<0.0001) 30/34 non-rapid sequence induction Ultrasound assessment of the gastric contents for the guidance of the anaesthetic strategy in infants with hypertrophic pyloric stenosis: a prospective cohort study British Journal of Anaesthesia 2016; 116(5): A.C. Gagey, M. de Queiroz Siqueira, F.P. Desgranges, et al.

36 The humane argument The pragmatic argumentHave you ever induced anaesthesia via an IO? Careful assessment, good judgement, good decision making, smooth execution

37 Conclusion Is inhalational induction justifiable in paediatric emergencies?Anatomical Airway Obstruction – yes Anterior mediastinal mass – yes Hypertrophic pyloric stenosis – yes Neonatal surgery – yes Older children at risk of aspiration – not my first choice but I would seldom rule it out completely

38 Conclusion To reduce the risk of aspirationReduce the gastric volume Increase the pH of the gastric contents Smooth induction Ensure an adequate depth of anaesthesia before attempts at intubation Complete muscle paralysis before laryngoscopy