Use of modified rapid sequence tracheal intubation in pediatric patients.

BACKGROUND: Rapid sequence intubation (RSI) has been an established practice, but is not without risks to patient. In different situations, a modification of the standard RSI technique may be more appropriate. The definition of a modified rapid sequence intubation (MRSI) is not well-documented. The purpose of this survey was to determine the working definition of MRSI as well as the modality of its use.
MATERIALS AND METHODS: This descriptive study consisted of a survey of pediatric anesthesiologists and included basic questions related to the anesthesiologist's experience, practice setting and use of MRSI. Responses were compiled and analyzed to identify the working definition, technique, perceived indications/complications as well as hands-on performance of tracheal intubation during use of MRSI in children.
RESULTS: The mean ± SD years in practice of the 228 respondents were 14.9 ± 8.16 years, with pediatric patients comprising 77 ± 33% of their practice. 76.8% completed a fellowship in pediatric anesthesia. 60% of the respondents' practice setting was at a Children's Hospital. Different respondents agreed with different techniques of MRSI with the majority (65%) defining a MRSI as equivalent to a RSI, but with mask ventilation. The major indication of use of a MRSI was a concern about apnea time tolerance with traditional RSI (74%).
CONCLUSION: Technique of a MRSI varies among pediatric care providers.

INTRODUCTION

Rapid sequence intubation (RSI) and modified rapid sequence intubation (MRSI) are the methods of choice for the majority of pediatric emergency tracheal intubations. Airway manipulations for endotracheal intubation in a pediatric patient are routinely based on the assessment of the patient's airway, the difficulty of tracheal intubation and the potential risk for aspiration. In different situations, a modification of the RSI technique may be more appropriate and may be a common practice in pediatric care. Considerable variation; however, may exist among providers in the use of this technique and different intubation techniques may qualify as a MRSI depending upon the practitioners. Variability may occur in the duration of preoxygenation, the selection, dosage and timing of administration of the induction agent and muscle relaxant, the application of cricoid pressure or other factors. The primary purpose of this survey was to determine the working definition of MRSI as well as modalities of its use in the clinical practice.

MATERIALS AND METHODS

After consultation with the Institutional Review Board (IRB), a waiver of IRB approval was granted. This descriptive study consisted of a survey of pediatric anesthesiologists who have completed training and are active members of the Society for Pediatric Anesthesia (SPA). It was submitted to and approved by the SPA research committee and sent via electronic mail to active members. The survey [Appendix 1] included basic questions related to the anesthesiologist's experience, practice setting and the modalities of use of MRSI. A second electronic mail reminder was sent if the survey was not returned. Responses were compiled and analyzed at the end of the survey to determine the technique, perceived indications and complications of use of MRSI in children.

RESULTS

The mean ± SD years in practice of the 228 respondents (estimated at 11% of available surveyed) was 14.9 ± 8.2 years with pediatric patients representing 77 ± 33% of their practice., 76.8% completed a fellowship in pediatric anesthesia. The median number of years after fellowship completion was 13.4 ± 8.1 years. 60% of the respondent's practice setting was at a Children's Hospital [Table 1]. The majority of respondents (65.4%) defined modified RSI as equivalent to a RSI, but with mask ventilation, 34.7% as equivalent to a RSI, but with the use of rocuronium instead of succinylcholine, 17.1% as equivalent to a regular intravenous (IV) induction, but with cricoid pressure application, 7.9% as a regular mask induction with cricoid pressure application, 6.6% as a RSI with pre or co-administration of narcotics or benzodiazepines, 3.1% as a regular induction without assisted ventilation/oxygenation from time of apnea to laryngoscopy, 2.2% as a RSI without preoxygenation, 2.6% all the above and 16.7% as other [Figure 1] (respondents were allowed to choose multiple answers). The reported frequency of use of a MRSI is documented in Figure 2, with 6.1% of respondents’ stated always using and 4.8% never using a MRSI technique. Indications of use of a MRSI were a concern about apnea time tolerance with traditional RSI, concern about muscular pathology if succinylcholine is used and concern about airway difficulty in 73.7%, 70%, and 44.2% of respondents, respectively [Figure 3]. The muscle relaxant of choice for a RSI in a pediatric patient was succinylcholine (62.2%), followed by rocuronium in 22.1% of respondents. The muscle relaxant of choice was rocuronium (62.7%), followed by succinylcholine in 12.4% of respondents who used the MRSI technique [Figure 4]. The age of patient was considered as a factor in choosing the muscle relaxant (i.e., concern about an undiagnosed neuromuscular pathology) in 35% of respondents using the MRSI technique. The minimum age of patients when succinylcholine is used is shown in Figure 5.

Table 1

Type of practice setting

Figure 1

Modified rapid sequence intubation definition

Figure 2

Frequency of use of modified rapid sequence intubation

Figure 3

Indications of modified rapid sequence intubation

Figure 4

Muscle relaxant of choice

Figure 5

Succinylcholine use and concern about muscular pathology

Of the respondents, 40.6% would wait until the O2 saturation is less than 95% to modify the RSI and 50% would wait until the O2 saturation is less than 90% to modify the RSI technique [Figure 4]. Complications upon using a MRSI were reported as none, desaturation, aspiration, difficulty in intubation associated with the induction technique and other in 48.8, 40.6, 12.4, 12 and 3.2% of respondents, respectively [Figure 6]. Most respondents somewhat agree that they consider that a RSI and a modified RSI offered a lower incidence of complications when compared with regular IV induction, in a pediatric patient at risk of aspiration [Figure 7]. 62.7% of respondents think that a cuffed tube should be used in a RSI or MRSI. In case of a high-risk for aspiration or a difficult airway, 32.7% of the respondents would consider an awake intubation in neonates only, 11% in both neonates and infants and 25.8% in all neonates, infants and children, 22.6% would never consider it. Cricoid pressure was more frequently applied by the anesthesiologist during the day shifts and by the operating room nurse during the night shifts [Figure 8].

Figure 6

Observed complications after modified rapid sequence intubation

Figure 7

Perception of a lower incidence of complications with rapid sequence intubation and modified rapid sequence intubation versus regular intravenous induction in a pediatric patient at risk for aspiration

Figure 8

Day shift versus night shift application of cricoid pressure

DISCUSSION

RSI as originally described, includes preoxygenation with 100% oxygen, administration of an IV induction agent, succinylcholine and cricoid pressure to facilitate tracheal intubation and apnea prior to securing the airway with an endotracheal tube (ETT).[1] RSI has been referred to as the standard of practice in prevention of aspiration; however, in pediatric practice, different considerations such as to the age and status of the patient and different agents administered may favor the use of a MRSI in place of the classic RSI.

In this survey, 65.4% of respondents perceived MRSI as identical to a RSI, but with mask ventilation. More variations to the RSI may be applied as shown in Figure 1. The majority of respondents included using the mask ventilation in their definition of MRSI. More recently, an editorial has described a “controlled rapid sequence induction” in pediatric patients with a consensus of its use in Europe.[2] The authors state that mask ventilation with pressures not exceeding 10-12 cm H2O allows oxygenation, limits hypercarbia and keeps the small airways open without the risk of gastric inflation and related morbidity.[34] This argument was based on applying this induction technique over many years at the authors’ and different institutions.

A total of 74% of respondents to the survey considered applying MRSI if they were concerned about apnea time tolerance with traditional RSI. A reduced tolerance to apnea, which may result from different factors such as increased oxygen demand, reduced functional residual capacity and increased closing capacity and very limited cooperation during the preoxygenation are related to age. Neonates and infants may develop hypoxemia (SpO2 < 90%) before full neuromuscular blockade is accomplished[567] and rapid desaturation may be more dramatic in severely ill-children.

The threshold to modify RSI technique was with oxygen saturation values less than 95% and less than 90% in 41% and 50% of respondents, respectively [Figure 4]. Since severe oxygen desaturation may occur rapidly past these values, stress and haste have been described as important factors with classic RSI in the pediatric population, triggering further complications such as forced mask ventilation and problems with intubation.[8]

The percentage of respondents using MRSI if concerned about muscular pathology was 70% [Figure 4] with rocuronium administered as the muscle relaxant of choice for pediatric MRSI (>60% of respondents) [Figure 5]. The use of succinylcholine has been debated in the pediatric literature and practice.[910] Its favorable use in RSI for aspiration prevention is related to its rapid effect minimizing the time that the airway remains unprotected. The youngest age category for starting administration of succinylcholine by the majority of anesthesiologists was in adolescents (45.2%) followed by neonates (27.4%) with 8.2% never using succinylcholine [Figure 6].

The majority (63%) of respondents replied that a cuffed tube should be used in a RSI or MRSI in a pediatric patient. The youngest age category for use of a cuffed ETT by the majority of respondents was in children. The traditional advantages for young children are that an uncuffed ETT with air leak exerts minimal pressure on the internal surface of the cricoid cartilage and allows insertion of an ETT of larger internal diameter, resulting in less airway resistance while cuffed ETT may offer a reduced number of endotracheal reintubation and decreased leak leading to a greater ease and consistency of delivery of high airway pressures and a theoretical attenuated incidence of aspiration.[11] In the presence of a high-risk of aspiration and/or difficult airway, 33% of respondents would consider awake intubation in neonates and 23% of respondents would never consider performing an awake intubation. Among different concerns of an awake tracheal intubation are adverse hemodynamic responses and the debatable increased risk of intraventricular hemorrhage in neonates.[12]

An important described component of aspiration prevention is the application of cricoid pressure. Well-known polemics related to cricoid pressure have been described in the literature.[131415] Cricoid pressure may distort the anatomy of the upper airway resulting in a difficult ventilation and tracheal intubation, especially in infants and neonates.[1617] Relaxation of the lower esophageal sphincter is an undesirable side-effect and performing cricoid pressure in a lightly anesthetized patient may result in bucking and coughing.[18] Pulmonary aspiration in patients during induction of anesthesia or during tracheal intubation despite the application of cricoid pressure has been described.[19] Esophageal pressures from active vomiting could overcome cricoid pressure, leading to pulmonary aspiration. It is indicated that cricoid pressure should be relieved immediately during active vomiting to avoid spontaneous rupture of the esophagus (Boerhaave's syndrome). On the other hand, the role of cricoid pressure in preventing passive regurgitation has been demonstrated in cadaveric studies.[20] The results of surveys from the United Kingdom indicated that RSI was modified more frequently for infants.[21] Cricoid pressure would include hyperextension of the neck with placement of a hard neck rest beneath the cervical curve, which may not be applicable due to the small size of the child. In the literature, several publications refer to a MRSI with the use of inhalation induction[2223] and RSI after pre-loading with narcotics[2425] or without the use of muscle relaxants.-[26] In this survey, 33% of respondents would consider a MRSI without administration of muscle relaxant when concerned about a muscular pathology [Figure 4]. In this survey, cricoid pressure was reported to be applied more frequently by the anesthesiologist during the day shifts and by the operating room nurse during the night shifts [Figure 8]. In children, appropriate force for a specific age group is not well-known. In the literature, different degrees of application and the questionable necessity of application of cricoid pressure have been described in different studies and reports.[2728]

In this survey, variation of use and observed complications of MRSI [Figure 7] may have been expected along with the variation of MRSI definition. The majority of the responders [Figure 8] agreed that MRSI offers a lower incidence of complications than regular IV induction in pediatric patients at risk for aspiration.