Preoxygenation before laryngoscopy in children: how long is enough?

Preprocedural Oxygenation and Procedural Oxygenation During Pediatric Procedural Sedation: Patterns of Use and Association With Interventions

STUDY OBJECTIVE

Preprocedural oxygenation (pre-emptive oxygenation started during presedation and/or induction) and procedural oxygenation (pre-emptive oxygenation started during any phase of sedation) are easy-to-use strategies with potential to decrease adverse events. Here, we describe practice patterns of preprocedural oxygenation and procedural oxygenation. We hypothesized that patients who received preprocedural oxygenation or procedural oxygenation would have a lower risk of airway/breathing/circulation interventions during sedation compared with patients without procedural oxygenation.

METHODS

We performed a retrospective, multicenter, cross-sectional study of pediatric sedations from April 2020 to July 2023 using the Pediatric Sedation Research Consortium multicenter database. The patient-level and sedation-level characteristics were described using frequencies and proportions, stratified by preprocedural oxygenation and procedural oxygenation status. We determined the site-level frequency of preprocedural oxygenation and procedural oxygenation use. We used inverse probability of treatment weighting to calculate the risk difference for interventions associated with preprocedural oxygenation and procedural oxygenation.

RESULTS

This study included a total of 85,599 pediatric sedations; 43,242 (50.5%) patients received preprocedural oxygenation (used oxygen before sedation and/or at induction) and a total of 52,219 (61.0%) received procedural oxygenation pre-emptively at any time during the sedation. There was no statistical difference in overall interventions with either preprocedural oxygenation (risk difference -0.06%; 95% confidence interval -4.26% to 4.14%) or procedural oxygenation (risk difference -1.07%; 95% confidence interval -6.44% to 4.30%).

CONCLUSION

Pre-emptive preprocedural oxygenation and procedural oxygenation were not associated with a difference in the use of airway/breathing/circulation interventions in pediatric sedations.

It's time to stop using nitrous oxide for pediatric mask induction

BACKGROUND

Mask induction of anesthesia for pediatric patients has included the use of nitrous oxide since the inception of pediatric anesthesia. However, the use of nitrous oxide precludes adequate preoxygenation. Additionally, pediatric physiology (less Functional Residual Capacity, higher oxygen consumption), increased risk of laryngospasm and lack of intravenous access increase the risk of a severe airway complication in the event of airway occlusion. Nitrous oxide does not facilitate tranquil mask placement on an unwilling child and does not meaningfully speed mask induction. Exposure to nitrous oxide has potential occupational health concerns and nitrous oxide has significant environmental detriment.

CONCLUSION

Utilizing other, evidence-based, techniques to facilitate tranquil mask placement will assure that patients have a pleasant induction experience and avoiding nitrous oxide will reduce the environmental impact, as well as improve the safety of, pediatric mask induction.

Preoxygenation: from hardcore physiology to the operating room

If we define the human body by the mass of the elements that compose it, we could say that we are oxygen and other elements. Oxygen, in addition to being fundamental in our composition, is an element that we constantly need to support cellular respiration and, therefore, life. Interestingly, despite its importance, humans have not developed mechanisms that allow us to store it and, therefore, we are unable to sustain life if we are deprived of ventilation, even for brief periods. Accordingly, the ability to induce the cessation of ventilation in a patient must be accompanied by different technical and non-technical skills that allow the patient's safety to be maintained in this highly vulnerable state. Through the use of basic mathematical tools and comparative physiology, we hereby propose to review the physiological foundations of preoxygenation to understand the reasons behind the clinical recommendations in this field.

Fraction of Expired Oxygen as a Measure of Preoxygenation Prior to Rapid Sequence Intubation in the Pediatric Emergency Department

BACKGROUND

Pulse oximetry (SpO₂) is a flawed measure of adequacy of preoxygenation prior to intubation. The fraction of expired oxygen (FeO₂) is a promising but understudied alternative.

OBJECTIVE

To investigate FeO₂ as a measure of preoxygenation prior to intubation in a pediatric emergency department.

METHODS

We conducted a prospective, observational study of patients 18 and younger. We collected data using video review, and FeO₂ was measured via inline sampling. The main outcomes were FeO₂ and SpO₂ at the start of preoxygenation, end of preoxygenation/start of intubation attempt, and the end of intubation attempt. We compared FeO₂ and SpO₂ at the end of preoxygenation for patients with and without oxyhemoglobin desaturation.

RESULTS

We enrolled 85 of 88 eligible patients during the 14-month study period. FeO₂ data were available at the start of preoxygenation for 53 of 85 patients (62%), and for the end of preoxygenation for 59 of 85 patients (69%). Median FeO₂ at the start and end of preoxygenation was 90% (interquartile range [IQR] 88, 92) and 90% (IQR 88, 92). Median SpO₂ at the start and end of preoxygenation was 100% (IQR 100, 100). There were 11 episodes of desaturation, with median FeO₂ at the start of intubation attempt of 89.5 (IQR 54.5, 91.5) and median SpO₂ of 100 (IQR 99, 100). Patients who did not have a desaturation event had a median FeO₂ of 90.0 (IQR 88.0, 92.0).

CONCLUSIONS

Measuring FeO₂ during rapid sequence intubation is challenging with feasibility limitations, but may be a more discriminatory metric of adequate preoxygenation.

[Ventilation in Pediatric Anesthesia]

About nine percent of all anesthesia procedures per year are performed in children. The risk for complications in pediatric anesthesia is higher in comparison with adults. There are significant differences in anatomy, physiology and pharmacology between pediatric and adult patients. Respiratory complications and circulations dysregulation occur more often in children. The most important consideration in the safe practice of pediatric anesthesia is to ensure a patent airway. Appropriate intraoperative management of newborns and infants needs a senior anesthetist with good knowledge and clinical experience including the management of possible complications.

Preoxygenation and Anesthesia: A Detailed Review

Initiation of preoxygenation prior to anesthetic induction and tracheal intubation is a commonly recognized technique intended to boost oxygen reservoirs in the body and thus slow the progression of desaturation of arterial hemoglobin at times of apnea. Even though challenges associated with ventilation and intubation are inconsistent, it is preferable for all patients to necessitate preoxygenation. The effectiveness of preoxygenation is measured by its performance and efficiency. Determinant factors of efficacy indices include rises in the alveolar O2 fraction (FAO2), reductions in the alveolar nitrogen fraction (FAN2), and improvements in the arterial O2 stress (PAO2). The effectiveness or efficiency of preoxygenation during apnea is evaluated from the declining trend in level of oxyhemoglobin desaturation (SAO2). The maximal risk associated with preoxygenation generally comprises delayed diagnosis of oesophageal intubation, absorption atelectasis, generation of reactive oxygen species, and incidences of adverse hemodynamic results. Since the time of preoxygenation is minimal, there are limited hemodynamic effects and the aggregation of reactive oxygen species to counteract its effectiveness. In general, three methods of preoxygenation techniques are followed for the routine procedures, namely, deep breathing, rapid breathing at fraction of inspired oxygen (FiO2) of 1 for two to five minutes, and the four vital capacities method. Health professionals, especially anesthesiologists specialized in Ear Nose and Throat (ENT) and traumatology, must be empowered by alternative methods like trans-tracheal ventilation to resolve life-threatening medical emergencies. Equipment accessibility and needful training are two essential components that are recommended for significant preparedness. The present article reviews the advantages conferred by the preoxygenation techniques with special attention to the high-risk population. It also details the inadequacies and the risks associated with the preoxygenation technique.

The management of unanticipated difficult airways in children of all age groups in anaesthetic practice - the position paper of an expert panel

Children form a specific group of patients, as there are significant differences between children and adults in both anatomy and physiology. Difficult airway may be unanticipated or anticipated. Difficulties encountered during intubation may cause hypoxia, hypoxic brain injury and, in extreme situations, may result in the patient’s death. There are few paediatric difficult-airway guidelines available in the current literature, and some of these have significant limitations. This position paper, intended for unanticipated difficult airway, was elaborated by the panel of specialists representing the Polish Society of Anaesthesiology and Intensive Care as well as the Polish Neonatal Society. It covers both elective intubation and emergency situations in children in all age groups. An integral part of the paper is an algorithm. The paper describes in detail all stages of the algorithm considering some modification in specific age groups, i.e. neonates.

Assessment of atropine-sufentanil-atracurium anaesthesia for endotracheal intubation: an observational study in very premature infants

Background

Premedication before neonatal intubation is heterogeneous and contentious. The combination of a short acting, rapid onset opioid with a muscle relaxant is considered suitable by many experts. The purpose of this study was to describe the tolerance and conditions of intubation following anaesthesia with atropine, sufentanil and atracurium in very premature infants.

Methods

Monocentric, prospective observational study in premature infants born before 32 weeks of gestational age, hospitalised in the NICU and requiring semi-urgent or elective intubation. Intubation conditions, heart rate, pulse oxymetry (SpO₂), arterial blood pressure and transcutaneous PCO₂ (TcPCO₂) were collected in real time during 30 minutes following the first drug injection. Repeated physiological measurements were analysed using mixed linear models.

Results

Thirty five intubations were performed in 24 infants with a median post conceptional age of 27.6 weeks and a median weight of 850 g at the time of intubation. The first attempt was successful in 74% and was similar for junior (75%) and senior (74%) operators. The operator rated conditions as “excellent” or “good” in 94% of intubations. A persistent increase in TcPCO₂ as compared to baseline was observed whereas other vital parameters showed no significant variations 5, 10, 15 and 30 minutes after the first drug injection. Eighteen (51%) desaturations (SpO2 less than or equal to 80% for more than 60 seconds) and 2 (6%) bradycardia (heart rate less than100 bpm for more than 60 seconds) were observed.

Conclusion

This drug combination offers satisfactory success rate for first attempt and intubation conditions for the operator without any significant change in heart rate and blood pressure for the patient. However it is associated with frequent desaturations and a possible persistent hypercapnia. SpO₂ and PCO₂ can be significantly modified during neonatal intubation and should be cautiously followed in this high-risk population.

Paediatric airway management: What is new?

Airway management plays a pivotal role in Paediatric Anaesthesia. Over the last two decades many improvements in this area have helped us to overcome this final frontier. From an era where intubation with a conventional laryngoscope or blind nasal intubation was the only tool for airway management, we have come a long way. Today supraglottic airway devices have pride of place in the Operating Room and are becoming important airway devices used in routine procedures. Direct and indirect fibreoptic laryngoscopes and transtracheal devices help us overcome difficult and previously impossible airway situations. These developments mean that we need to update our knowledge on these devices. Also much of our basic understanding of the physiology and anatomy of the paediatric airway has changed. This article attempts to shed light on some of the most important advances/opinions in paediatric airway management like, cuffed endotracheal tubes, supraglottic airway devices, video laryngoscopes, rapid sequence intubation, the newly proposed algorithm for difficult airway management and the role of Ex Utero Intrapartum Treatment (EXIT) procedure in the management of the neonatal airway.

Standard preoxygenation vs two techniques in children

BACKGROUND

Preoxygenation is recommended in pediatric anesthesia but it has been poorly assessed. Fractional expired oxygen concentration (F(ET)O(2)) is a preoxygenation monitor. The aim of this prospective study in children was to compare three techniques of preoxygenation by the measurement of F(ET)O(2).

METHODS

Twenty children (6-15 years) were included. F(ET)O(2) was measured with the child in a supine position, holding the face mask. The F(ET)O(2) value was measured after 3 min of calm breathing of room air (baseline) and during the three preoxygenation techniques performed in random order: 3 min of tidal volume breathing using an O(2) flow of 9 l x min(-1) (TV x 3 min)--four deep breaths within 30 s using an O(2) flow of 15 l x min(-1) (4 DB)--eight deep breaths within 1 min using an O(2) flow of 15 l x min(-1) (8 DB). Between each technique, at least 5 min breathing room air was allowed to return to baseline F(ET)O(2). Fisher's exact test was used and P < 0.05 was considered significant.

RESULTS

Twenty children were studied (age: 11.5 +/- 3 years, weight: 42 +/- 21 kg). The F(ET)O(2) > or = 90% was found to be 79% in 74 +/- 40 s with TV x 3 min, 11% with 4 DB, and 68% with 8 DB.

CONCLUSIONS

In children, Vt x 3 min is the most efficient preoxygenation technique to reach F(ET)O(2) > or = 90%.

The development of hypoxaemia during apnoea in children: a computational modelling investigation

BACKGROUND

Hypoxaemia during apnoea develops earlier and progresses faster in children than in adults. Ethical and practical considerations prevent detailed investigation of the issue.

METHODS

We used the Nottingham Physiology Simulator, an integrated, computational model of the respiratory and cardiovascular systems, to model four healthy virtual children (ages: 1 month, 1, 8 and 18 yr) and exposed them to apnoea after a variety of preoxygenation periods (0, 1 and 3 min) and with open and obstructed airways during apnoea.

RESULTS

The rate of oxygen desaturation of haemoglobin from 90 to 40% was similar across the ages studied, being approximately 30% min(-1). The greatest difference between ages was found in the speed of early desaturation (i.e. between the onset of apnoea and the acceleration of haemoglobin desaturation); in the absence of preoxygenation and with an open airway, this time was 6.6 s in the 1-month-old and 33.6 s in the 8-yr-old.

CONCLUSIONS

Preoxygenation had a substantial effect on the speed of early desaturation, but less effect on the time for SaO2 to decrease from 90 to 40%. Preoxygenation substantially delayed dangerous desaturation in all age groups, although the rapidity of denitrogenation in the very young (caused by the large ratio of minute ventilation to functional residual capacity) resulted in lengthy preoxygenation having little benefit over brief preoxygenation. Airway obstruction during apnoea accelerated every child's hypoxaemia through prevention of mass flow addition to oxygen stores and through intrathoracic depressurization. On average, haemoglobin desaturation from SaO2 90 to 40% was 33% min(-1) with an obstructed airway and 26% min(-1) with an open airway; all ages were similarly susceptible to this effect.

Major abdominal surgery of the neonate: anaesthetic considerations

The anaesthetic handling of neonates scheduled for major abdominal surgical procedures is one of the most demanding tasks that can confront an anaesthesiologist. This chapter will review the specific physiological characteristics of the newborn with relevance to anaesthesia and will also provide robust guidelines for the anaesthetic handling of the most frequent diagnoses that need major abdominal surgery during the neonatal period.

Premedication for tracheal intubation: A prospective survey in 75 neonatal and pediatric intensive care units*

OBJECTIVE

In children, like in adults, tracheal intubation is a painful procedure that may induce hypertension, tachycardia, and other undesirable hemodynamic disorders. Although premature neonates are very sensitive to pain and vulnerable to its long-term effects, the need for sedation before tracheal intubation is still discussed in neonatal units. Our objective was to investigate the practice of premedication before tracheal intubation in neonatal and pediatric units and determine the influence of premedication on intubating conditions.

DESIGN

We performed a 10-day prospective survey in 75 neonatal and pediatric intensive care units among the 98 licensed in France. A questionnaire was completed for each intubation performed in each surveyed unit.

SUBJECTS

A total of 204 patients were studied: 140 neonates, 52 infants, and 12 children.

MAIN RESULTS

Data on 204 tracheal intubations were collected from 223 that were performed during the study period (participation rate, 91.4%). Premedication was used before intubation for 37.1%, 67.3%, and 91.7% of neonates, infants, and children, respectively (p <.0001). In the subgroup of neonates, premedication was particularly rare for the youngest and the smallest infants. Midazolam was the principle hypnotic used in neonates, whereas propofol was mainly used in children. Opioids or muscle relaxants were used in 16.2% and 4.4% of the patients, respectively. A low success rate and a high incidence of hypoxemia and bradycardia were correlated with the inexperience of the operator. Premedication did not significantly influence either the success rate or the undesirable events associated with tracheal intubation.

CONCLUSION

Use of premedication before tracheal intubation is limited in neonates and increases according to the age of the patient. Midazolam does not seem to be an accurate choice to improve intubating conditions in neonates and infants. Because tracheal intubation is a technique that requires a skill only developed by regular practice, operators who have limited experience with intubating children should be supported by senior operators.

[Airway protection in children with a full stomach]

Recent surveys have reevaluated the risk of aspiration of gastric content during anesthesia in pediatric patients. Emergency, bowel obstruction and inadequate depth of anesthesia are the main high-risk situations. Airway protection requires the placement of cuffed tracheal tube. Cuffed tubes were considered as non-useful in children aged less than 6 to 8 years. They are however more frequently employed even in infants. Internal diameter of cuffed tubes should be reduced compared to uncuffed tubes. It is recommended to monitor cuff pressure if nitrous oxide is used during anesthesia. Crash induction is described with special reference to pediatric specificities.

Rapid sequence intubation of the pediatric patient. Fundamentals of practice

Rapid-sequence intubation and rapid sequence induction of general anesthesia are synonyms and refer to the technique of choice for tracheal intubation in many pediatric patients in the emergency department. The principles of safe practice and basic standards of care uniformly apply to all clinical situations in which the technique is performed. RSI has two basic technical components: induction of general anesthesia and direct laryngoscopy with tracheal intubation. The technique is a prescribed protocol that can be modified slightly by the clinical circumstances. RSI is designed to rapidly create ideal intubating conditions, attenuate pathophysiologic reflex responses to direct laryngoscopy and tracheal intubation, and reduce the risk for pulmonary aspiration. Optimal performance requires appropriate training and knowledge, technical skill, and sound medical judgment. Medical and airway evaluation, careful patient selection, recognition of the need for consultation or safer alternatives, thorough familiarity with appropriate drug management, and attention to detail are essential for minimizing the risk for adverse complications. RSI with a rapid injection of preselected dosages of an anesthetic induction agent and muscle relaxant is the pharmacologic technique of choice. Premedication should not be routinely used. Anticipation, recognition, and management of complications are inherent to the competent delivery of all medical care. The unanticipated difficult airway is arguably the most severe complication of RSI, and all individuals performing the technique must prepare in advance a specific plan for this scenario. As with all such skills or procedures, a quality assurance program is important to monitor care, and individuals practicing RSI need to take appropriate steps to maintain competence.