SPA Spring Meeting Reviews
Friday Session I – International Myth Busters: Across the Pond
By Erin S. Williams, MD, FAAP
Texas Children’s Hospital
Baylor College of Medicine
At the Society for Pediatric Anesthesia (SPA) 2020 Annual Meeting, SPA registrants were pleasantly greeted by the smooth sounds of the Caribbean as they entered the Imperial Ballroom of the Atlantis. The vibrant beat of steel drums captivated their attention and helped them reset in preparation for focusing on learning the latest information in pediatric anesthesiology.
Dr. Shobha Malviya moderated the first informative session which was comprised of four distinct topics given by four leaders in pediatric anesthesiology.
Fasting Guidelines and Consensus Statement: Current Status and Future Directions
The first presentation was given by Nicola Disma, MD, a consultant pediatric anesthetist at the Ist. G. Gaslini of Genoa, Italy. He serves as Chairman of the European Society of Anesthesiology (ESA) scientific committee and the Guidelines Taskforce. He eloquently spoke about current fasting guidelines for the pediatric patient.
Dr. Disma began with background information stating that both the American Society of Anesthesiologists (ASA) and the ESA recommend nil per os (NPO) time prior to surgery of two hours for clears, four hours for breastmilk, and six hours for a light meal (2-4-6). Interestingly, there is no proven association between fasting time and pulmonary aspiration. Dr. Disma then gave the audience a summary of recent data regarding fasting prior to surgical procedures and the impetus behind minimizing NPO time.
Oftentimes we are posed with the question of 'how long do we have to wait' when a patient has 'violated' NPO time prior to surgery. Given the inability to truly say that inadequate fasting leads to the negative outcome of pulmonary aspiration, this can be difficult to answer. To help better equip the pediatric anesthesiologist in this situation, Dr. Disma set out to answer the following questions:
- What’s the real incidence of pulmonary aspiration?
- What are the risk factors for pulmonary aspirations?
- What new tools can be utilized to evaluate the presence or absence of gastric contents?
Briefly, the original recommendation to allow clear liquids up to two hours prior to surgery was based on data from several papers from the 1990s. Of note, in 1990, Miller et al. looked at gastric volume contents after a three-hour fast and found no difference compared to those with longer or shorter fasting times. Additionally, in 1993, Phillips et al. concluded that drinking did not affect gastric contents. Later in 1996, Eriksson et al. evaluated fasting guidelines in different countries. Review of the literature led the Association of Pediatric Anesthetists (APA), European Society for Paediatric Anesthesiology, and ADARPEF to make the following general consensus statement - “it is safe and recommended for all children able to take clear liquids to be allowed and encouraged to have them up to one hour before general anesthesia.”
Again, when considering lack of association between fasting and pulmonary aspiration, Dr. Disma directed the audience to a 2016 paper by Beach et al. that showed no increased aspiration in children who were not NPO compared to those who were. Also, the APRICOT group found 9/10,000 or 0.1% of cases to have aspiration. Additionally, it was noted that 11/29 or 0.4% of aspiration events occurred during emergency cases, potentially indicating that emergency cases are a risk factor for aspiration.
Dr. Disma went further and discussed the 2019 German audit by Beck et al. that looked at 3,300 pediatric surgical patients and found an incidence of 0.12% of suspected pulmonary aspiration and an incidence of 0.06% of definite aspiration. The low incidence is thus encouraging regarding decreasing duration of fasting times.
In addition to the low incidence of pulmonary aspiration, actual clinical implications of prolonged fasting were discussed. As physicians we all must consider what imposed fasting means for both patient and family. In a 2020 paper in Paediatric Anesthesia, child comments associated with fasting were documented. Comments ranged from “not bothered” and “understanding” to “upset” and “nervous.” The latter of course being the most concerning and stressing the need to limit fasting durations to ultimately improve patient care and satisfaction.
When it comes to gastric emptying physiology, Andersson et al. showed most gastric contents to be gone at one hour for clears, three hours for milk, and 4-9 hours for solids. In 2015, Andersson et al. also showed only a 0.03 % incidence of aspiration when looking at 10,000 patients who were allowed to drink up until being called for surgery. Finally, in 2019 Isserman et al. looked at 16,000 cases at Children’s Hospital of Philadelphia (CHOP) and after drinking clears up to one hour prior to surgery there was an increase in regurgitation but no increase in aspiration.
Given the lack of association of aspiration with fasting and the low incidence of aspiration, the recommendation for 1-4-6 NPO times is supported. Additionally, objective evaluation of gastric volume and contents was the final component of Dr. Disma’s presentation. Use of gastric ultrasound can be a fast and effective tool for determining if more fasting time is necessary or if a different plan is needed prior to induction of anesthesia. Dr. Disma stated that gastric ultrasound may be of use in situations such as lack of adherence to fasting recommendations (emergencies, miscommunication), unreliable or unclear fasting history, and conditions with potential delay in gastric emptying (diabetes or neuromuscular disorders).
Finally, Dr. Disma left the audience with these take-home points:
- Allow drinking
- Encourage drinking
- Limit fasting duration when possible
- Pursue and evaluate ongoing prospective studies
- Al-Robeye et al. Thirsty work: Exploring children's experiences of preoperative fasting. Paediatr Anaesth. 2020 Jan;30(1):43-49.
- Andersson H et al. Low incidence of pulmonary aspiration in children allowed intake of clear fluids until called to the operating suite. Paediatr Anaesth. 2015 Aug;25(8):770-777.
- Andersson et al. Preoperative fasting guidelines in pediatric anesthesia: are we ready for a change? Curr Opin Anaesthesiol. 2018 Jun;31(3):342-348.
- Beach et al. Major Adverse Events and Relationship to Nil per Os Status in Pediatric Sedation/Anesthesia Outside the Operating Room: A Report of the Pediatric Sedation Research Consortium. Anesthesiology. 2016 Jan;124(1)80-8.
- Beck CE, et al. Real fasting times and incidence of pulmonary aspiration in children: Results of a German prospective multicenter observational study. Pediatr Anesth. 2019;29:1040–1045.
- Disma N et al. European Journal of Anaesthesiology (EJA)2019; 36: 173–174.
- Miller et al. Gastric residual volume in infants and children following a 3-hour fast. J Clin Anesth. 1990 Sep-Oct;2(5):301-5.
- Phillips et al. Preoperative drinking does not affect gastric contents. Br J Anaesth. 1993 Jan;70(1):6-9.
- Eriksson LI, Sandin R. Fasting guidelines in different countries. Acta Anaesthesiol Scand. 1996 Sep;40(8 Pt 2):971-4.
- Gagey et al. The effect of pre-operative gastric ultrasound examination on the choice of general anaesthetic induction technique for non-elective paediatric surgery. A prospective cohort study. Anaesthesia. 2018 Mar;73(3):304-312.
- Habre et al. Incidence of severe critical events in paediatric anaesthesia (APRICOT): a prospective multicentre observational study in 261 hospitals in Europe. Lancet Respir Med. 2017 May;5(5):412-25.
- Isserman R et al. Quality improvement project to reduce pediatric clear liquid fasting times prior to anesthesia. Paediatr Anaesth. 2019 Jul;29(7):698-704.
Airway Management for T&A…Are Supraglottic LMAs Appropriate?
The esteemed Kirk Lalwani, MBBS, FRCA, MCR, Professor of Anesthesiology and Pediatrics from Oregon Health and Science University in Portland, Oregon gave a power-packed talk on the use of laryngeal mask airways (LMAs) for tonsillectomy and adenoidectomy surgery. Dr. Lalwani opened his presentation with a thought provoking directive, “Imagine a world without LMAs.” Such a thought was the reality that Dr. Lalwani lived prior to Dr. Archie Brain’s life-saving invention which was prototyped in 1981 and went into clinical use in the late 1980s. Given the routine use of the LMA for a variety of surgical cases and arenas, there can be a benefit for its use during tonsillectomies and adenoidectomies (T&As).
Dr. Lalwani expertly involved the audience utilizing the live polling tool. This worked to keep the learners engaged. With regard to answering the question, “Are LMAs appropriate for T&As?”, Dr. Lalwani looked at the literature.
In 2007, Dr. Mark Hamilton and Dr. Anil Patel of the Royal ENT Hospital in London commented to the Editor of Anesthesia and Analgesia that they performed 10,000 T&As over a 14-year period using the flexible LMA in more than 90% of their surgeries with minimal complication. It was also indicated that successful use of the LMA for “intraoral” surgeries requires training, knowledge, and skills for both anesthesiologists and surgeons.
Additionally, Dr. Lalwani discussed common concerns associated with LMA use. These included:
- LMA placement, displacement, or obstruction
- Surgical perspective or concerns
- Perioperative respiratory adverse events
- Regurgitation and aspiration
- LMA use in children with URIs
- Postoperative complications
With regard to LMA placement, Dr. Lalwani presented a video that gave audience members the step-by-step approach for correct placement of the LMA. This visual demonstration was excellent in allowing all levels of learners present the opportunity to see correct placement. Dr. Lalwani also presented the paper by Choo et al. regarding use of the laryngoscope instead of the LMA. Laryngoscopy-aided placement led to a 96% first time successful placement vs 81% without laryngoscopy. Additionally, they found that there was less sore throat associated with laryngoscopy-assisted placement (16% vs 35%).
With regard to surgical concerns, they range from mouth gag placement leading to obstruction of the airway or leakage, accidental severing of the pilot balloon, and need for intermittent positive pressure ventilation. In fact, in 2001, Hern et al. stated that the LMA gave inferior access to the operative site, leading to less tissue being excised; and there was a 10% LMA fail rate, meaning the patient had to be intubated. Additionally, in 2014, Hettige et al. showed that there was a significant learning curve for surgeons performing T&A with an LMA and there was a higher intraoperative intervention rate with less trained surgeons compared to more skilled surgeons (50% vs 10%).
With regard to adverse respiratory events, in 2009 Wilson et al. showed younger patients (younger than three years old) to have more complications with mouth gag placement and LMA use. Four years later in 2013, Lalwani et al. retrospectively looked at 1,200 pediatric patients undergoing T&A with LMA and found several predictors for failure and complications: younger age, IPPV, tonsillectomy, co-morbidities and surgeon familiarity and adaptability.
Additionally, in 1993, Webster et al. showed the LMA to be a safe alternative to the endotracheal tube (ETT) for adenotonsillectomy. In 2011, Peng et al. found LMA to have a significantly shorter time to extubation compared to ETT. Five years later, Xu et al. performed a review of randomized controlled trials (RCTs) that showed no difference in airway complications such as laryngospasm and airway displacement. However, there was less coughing, hoarseness and desaturations with LMA use. Most recently in 2019 Li et al. showed LMAs reduce the incidence of perioperative respiratory adverse events (PRAEs) in children and should be used.
Dr. Lalwani went further and spoke to the removal of LMAs (deep vs awake). Deep removal was associated with fewer airway complications in one study while another study showed no major difference in airway events when considering deep versus awake removal of the LMA.
In summary, if given the opportunity, and sufficient training and knowledge, the LMA is certainly an airway device to be considered for ENT surgery.
- Choo CY, Koay CK, Yoong CS. A randomized control trial comparing two insertion techniques for laryngeal mask airway Flexible TM in patients undergoing dental surgery. Anaesthesia 2012 Sep;67(9), 986-90.
- Hamilton, MA, Patel, A. Laryngeal mask airway and tonsillectomy: a question of training. Anesthesia & Analgesia: May 2007 - Volume 104 - Issue 5 - p 1312-1313.
- Hern JD et. Al. The laryngeal mask airway in tonsillectomy: The surgeon's perspective. Clinical otolaryngology and allied sciences. 1999 Apr;24(2):122-5.
- Hettige et al. Laryngeal mask airways and use of a Davis-Boyle gag in ENT surgery: Is there a learning curve? A prospective analysis. The Annals of Otology Rhinology and Laryngology. 2014 May 123(5) 338-42.
- Lalwani et al. The laryngeal mask airway for pediatric adenotonsillectomy: predictors of failure and complications. International Journal of Pediatric Otorhinolaryngology. 2013 Jan;77(1):25-8.
- Li et al. The impact of laryngeal mask versus other airways on perioperative respiratory adverse events in children: A systematic review and meta- analysis of randomized controlled trials. Int J Surg. 2019 Apr;64:40-8.
- Matthew PJ, Matthew JL. Early versus late removal of the laryngeal mask airway (LMA) for general anaesthesia. Cochrane Database Syst Rev. 2015 Aug;10:(8).
- Peng et al. Use of laryngeal mask airway in pediatric adenotonsillectomy. Arch Otolaryngol Head Neck Surg. 2011 Jan;137(1):42-6.
- Ramgolam et al. Deep or awake removal of laryngeal mask airway in children at risk of respiratory adverse events undergoing tonsillectomy-a randomized control trial. Br J Anaesth. 2018 Mar;120(3):571-80.
- Webster et al. Anaesthesia for adenotonsillectomy: a comparison between tracheal intubation and the armoured laryngeal mask airway. Can J Anaesth. 1993 Dec;40(12):1171-7.
- Wilson et al. Younger Pediatric adenotonisllar patients exhibit more complications at mouth gag insertion with LMA use. International Journal of Pediatric Otorhinolaryngology. 2009 Aug;73( 8):1173.
- Xu et al. Airway Complications during and after General Anesthesia: A Comparison, Systematic Review and Meta-Analysis of Using Flexible Laryngeal Mask Airway. PLos One. 2016 Jul;14(11):7.
Is Rapid Sequence Intubation Still Necessary in Pediatric Anesthesia?
We were privileged to have Lazlo Vutskits, MD, PhD, Head of Pediatric Anaesthesia, Department of Anesthesiology, Pharmacology and Critical Care, University Hospitals, Geneva, Switzerland render an excellent talk regarding whether or not we still need rapid sequence intubation.
Dr. Vutskits began his lecture with a poll of the audience. He gave a clinical scenario as follows:
A 3.1 Kg baby with pyloric stenosis presents to the OR for pyloromyotomy. How would you proceed?
- Rapid sequence induction
- Standard intravenous induction
- Inhalational induction with sevoflurane
By a show of hands there was representation for each of the above answers. He used these varied responses to walk us through the literature.
In 2015, Scrimgeour et al. looked at the use of gas induction for pyloromyotomy and found that out of 269 patients, approximately 94% had inhaled induction, approximately 6% had IV inductions comprised of both standard IV and RSI induction. There were no aspirations, thus making gas induction a possible option for these patients. However, in an accompanying editorial, Drs. Wang and Mancuso state that the lack of respiratory events is attributed to the excellent skill and expertise of the anesthesiologists. Thus, because the skill level can vary greatly among anesthesiologists, there is a hesitancy to recommend inhaled induction for pyloromyotomy patients given the concern for potential aspiration.
'So, which view point is correct?' you may ask. Dr. Vutskits explained the rationale behind RSI, mainly reminding the audience that avoidance of pulmonary aspiration is the key. We were reminded of the very tragic death of the previously healthy 15-year-old, Hannah Greener, who is believed to have lost her life due to pulmonary aspiration while having a toenail removed. She was receiving chloroform as her anesthetic; however, it is unclear if aspiration or a fatal cardiac arrhythmia was the ultimate cause of death. Interestingly, at autopsy she was found to have a full stomach. Given the fact that this occurred more than 170 years ago we may never know exactly what occurred. However, her demise brings to light the potentially fatal consequences of massive pulmonary aspiration in pediatric anesthesia.
Dr. Vutskits also reviewed the case of pulmonary aspiration during obstetric anesthesia which offered the first description of Mendelson’s syndrome. Mendelson syndrome is the chemical pneumonitis that arises after aspiration of gastric contents. After reviewing 44,000 obstetric cases, 66 were found to have aspirated and two of the 66 died after aspirating solid food and the remaining 64 had no major sequalae due to aspiration of liquid contents.
When it comes to prevention of aspiration, Dr. Vutskits reviewed the Sellick Maneuver which involves placing downward pressure on the cricoid cartilage during induction so as to prevent or decrease gastric contents from entering the trachea during loss of protective airway reflexes. Currently there are no randomized control trials proving beneficial outcomes with the Sellick Maneuver. Additionally, the application of such pressure can potentially compromise visualization of the glottis in very young patients.
So what evidence actually shows benefit of RSI for pediatric patients? In 1993 Warner et al. retrospectively looked at over 170,000 patients who received over 200,000 anesthetics and found pulmonary aspiration occurred in 67 patients (0.03%). Interestingly, it was noted that if patients did not develop clinical symptoms within two hours of aspiration, they did not have major respiratory morbidity. Additionally, ASA 1 and two patients did not have significant morbidity.
Dr. Vutskits reviewed the findings of Kluger and Short regarding the presence of 133 cases of aspiration of 5000 cases reported in the Australian Anaesthetic Incident Monitoring System. It was found that level of experience minimized aspiration, whereas inexperience and fault of technique contributed to this complication. Again, significant morbidity was not seen although there were five deaths, making the prevention of aspiration paramount in anesthetic management.
Perhaps the best way to approach the question of whether or not to use RSI involves the need for more RCTs. In 2007 Neilipovitz and Crosby performed a MEDLINE search from 1966 to 2007 and found no RCTs that showed a decrease in pulmonary aspiration incidence with RSI use.
Given the low incidence and low morbidity of pulmonary aspiration, again, Dr. Vutskits presented the increased incidence of complications with RSI in young children. In a 2010 study, Gencorelli and colleagues retrospectively reviewed a cohort of children ages 3-12 years of age and found hypoxemia (more likely in children < 20 Kg), failed intubation attempts, traumatic intubation, bradycardia, and increased risk for pulmonary aspiration.
Finally, given the low incidence of pulmonary aspiration and the increased risk of complications when RSI is done in the smaller population, we were reminded to remember the initial comments in the previously mentioned editorial: it will be prudent to have the person with greatest expertise and skill instrumenting the airway.
- Gencorelli FJ et al. Complications during rapid sequence induction of general anesthesia in children: a benchmark study. Paediatr Anaesth. 2010 May;20(5):421-4.
- Scrimgeour GE. Gas induction for pyloromyotomy. Paediatr Anaesth. 2015 Jul;25(7):677-80.
- Kluger MT, Short TG. Aspiration during anaesthesia: a review of 133 cases from the Australian Anaesthetic Incident Monitoring Study (AIMS). Anesthesia. 1999 Jan;54(1):19-26.
- Knight PR, Bacon DR. An unexplained death: Hannah Greener and chloroform. Anesthesiology. 2002 May;96(5):1250-53.
- Mendelson CL. The aspiration of stomach contents into the lungs during obstetric anesthesia. American Journal of Obstetrics and Gynecology. 1946; 52:191-205.
- Neilipovitiz DT, Crosby ET. No evidence for decreased incidence of aspiration Can J Anaesth. 2007 Sep;54(9):748-64.
- Wang JT, Mancuso TJ. How to best induce anesthesia in infants with pyloric stenosis? Paediatr Anaesth. 2015 Jul;25(7):652.
Neurocognitive Outcome Update
The final lecture of Session I was given by the renowned Andrew J. Davidson, MBBS, FANZCA, (Royal Children’s Hospital Melbourne). Dr. Davidson rendered a rapid fire summary of updates regarding neurocognitive outcome.
He began with the concept of translation. Are we able to take information or data from animal studies and deem it pertinent to humans? In theory, it is possible for anesthetics given in high enough concentrations to have a similar effect on humans as seen in animals. However, there are several concepts to consider when attempting to make the animal data directly translatable to humans. Some ideas to consider include the following:
- Some animal models may be irrelevant to human models.
- It is unclear as to the role age or surgery plays.
- There is a lack of clarity as to which neurologic domain will be affected.
- Many other factors may need to be considered (timing, type, and location of insult).
With that understanding, potential for a good outcome may depend on the possibility of recovery from injury. If there is injury at a time and location when there is no recovery, then this can lead to the bad outcome of neurocognitive impairment or morbidity. Dr. Davidson also reminded us to consider existing genetic predispositions and environmental factors.
When considering human study design, Dr. Davidson spoke about the use of data linkage studies which can be used to look at large populations of a country. Outcomes can then be determined by using a standardized preschool test. Of note, there can be preexisting factors that affect the results of the test.
The audience was reminded that birth cohort or longitudinal studies are also used in human studies. These can provide more detailed information regarding outcome measures such as psychometric testing. The size of these studies is not as big as linkage studies but the potential to give diagnosis of disability can be beneficial.
The purpose built cohort studies are ideal in that there is a group of patients exposed to anesthesia and a group not exposed. These two groups are compared. However, obtaining a large enough sample for each group may be challenging.
Another concept to consider is confounding. This can be lessened or reduced by being strategic with sample selection and matching. When confounding is present it may be difficult to pinpoint precise causation. Dr. Davidson discussed prospective studies which can help to eliminate nonrandom confounding. However, they can be quite labor intensive with regard to long-term follow-up and choosing the correct interventions to compare.
The main point is that parents want to know if the anesthetic will affect their child and how the effect will be demonstrated. These two concepts are still not easily answered. We have school grades or standardized readiness tests to compare outcomes however, gaps still exist in the ability to determine learning disabilities or neurodevelopmental disorders.
Dr. Davidson also alluded to the benefit of imaging in diagnosing neurodevelopmental disorders. Specifically, MRI may be helpful, keeping in mind the potential issues such as costs, type I errors and the need to have a clinical or functional correlation to the imaging findings.
Summarizing the information up to 2018, most, but not all, studies show some level of association between anesthesia exposure and neurocognitive impairment. Additionally, the more the exposure to anesthesia, the greater the association. This can be seen in small differences in school grades and readiness. There does appear to be strong evidence for association between major surgery in neonates and increased neurodevelopmental impairment.
In 2016, Davidson et al. found no increase in neurodevelopmental derangements at two years of age in patients who had a short duration of exposure (less than one hour) to sevoflurane compared to patients who underwent a regional anesthetic. Studying the same patients at age five, McCann et al. found no direct negative neurodevelopmental outcomes. In the MASK study, it was found that multiple exposures to general anesthesia in patients younger than three years of age may be associated with a negative neurodevelopmental outcome. The deficiencies seen included visual motor integration, processing speed and motor skills, all of which may be associated with attention deficit hyperactivity disorder (ADHD).
Most recently in 2020, Ing and colleagues reported children who had a one-time exposure to anesthesia younger than five years of age are 37% more likely to be prescribed ADHD medication compared to children who have never been exposed to anesthesia.
Dr. Davidson drove home the point that ultimately the question of whether or not anesthesia affects children may be best answered with further RCTs. Currently, given the shortcomings of translation, human study design, and other factors such as age, timing, and location of the insult the answer may be 'it depends…'
To conclude, Dr. Davidson provided reassuring information that anesthesia has no effect on IQ, and there is weak association between anesthesia and ADHD and readiness for school. When it comes to neonates undergoing major surgery there is association with poor outcome. He indicated we will likely be unable to completely rule out neurotoxicity in humans; however, it is still prudent to delay a surgical procedure in the very young if possible. Most importantly, we were reminded to remain ready to discuss this sensitive topic of anesthesia and neurocognitive outcome with parents.
- Davidson AJ et al. Neurodevelopmental outcome at 2 years of age after general anaesthesia and awake-regional anaesthesia in infancy (GAS): an international multicentre, randomized controlled trial. Lancet. 2016 Jan 16;387(10015):239-50.
- Ing C. Exposure to Surgery and Anesthesia in Early Childhood and Subsequent Use of Attention Deficit Hyperactivity Disorder Medications. Anesth Analg. 2020 Jan 8.
- McCann ME et al. Neurodevelopmental outcome at 5 years of age after general anaesthesia or awake-regional anaesthesia in infancy (GAS): an international, multicentre, randomised, controlled equivalence trial. Lancet. 2019 Feb 16;393(10172):664-677.
- Zaccariello MJ. Patterns of neuropsychological changes after general anaesthesia in young children: secondary analysis of the Mayo Anesthesia Safety in Kids study. Br J Anaesth. 2019 May;122(5):671-681.