Cricoid pressure

A Survey of Paediatric Rapid Sequence Induction in a Department of Anaesthesia

(1) Background: Rapid sequence induction (RSI) is carried out by anaesthetists to secure the airway promptly in patients who are at risk of aspirating gastric content during induction of anaesthesia. RSI requires variation in the paediatric population. We conducted a survey to investigate current practice of paediatric RSI by anaesthetists. (2) Methods: A descriptive, contextual, cross-sectional research design was followed. The study population consisted of all anaesthetists working in the Department of Anaesthesia at the University of the Witwatersrand. Data was collected in the form of a self-administered questionnaire. (3) Results: Of 138 questionnaires that were distributed, 126 were completed. Clinical indication for RSI was predominantly for appendicitis with peritonitis (115/124; 92.7%). Preoxygenation was performed by 95.1% of anaesthetists for children, 87% for infants and 89.4% for neonates. Cricoid pressure was used significantly more in children (56%) than in infants (20.8%) and neonates (10.3%) (p < 0.001). Rocuronium was the paralytic agent of choice in children (42.7%) and infants (38.2%), while cisatracurium was used most frequently in neonates (37.4%). Suxamethonium was used least in neonates. Cuffed ETTs were used most frequently for children (99.2%) and least for neonates (49.6%). Eighty-five percent of anaesthetists omitted cricoid pressure during RSI for pyloromyotomy, for which a controlled RSI was performed more by consultants and senior registrars (p < 0.01). A classic RSI was performed by 53.6% of anaesthetists for laparotomy for small bowel obstruction. Consultants and PMOs were more likely to intubate a child for forearm MUA who was starved for 6 h and received opioids (p < 0.05). Controlled RSI with cisatracurium was the technique of choice for Tenkhoff insertion in a child with renal failure. (4) Conclusions: RSI practice for paediatric patients varied widely among anaesthetists. This may be attributed to a combination of anaesthetic experience, training in paediatric anaesthesia, and patient specific factors, along with the individualised clinical scenario’s aspiration risk. A controlled RSI technique appears to be implemented more frequently by anaesthetists with increased experience.

Cricoid Pressure: Contradictory Evidence Regarding a Standard Practice

The purpose of applying cricoid pressure is to prevent pulmonary aspiration of regurgitated gastric contents during airway management in mask-ventilated patients who are at risk of aspiration. Providers may apply cricoid pressure during induction and intubation if they expect a difficult intubation or if the patient has a high risk for regurgitation. Although the application of cricoid pressure has been accepted as a standard practice worldwide, controversy persists because pulmonary aspiration can occur even when cricoid pressure is applied. The perioperative nurse should have thorough knowledge of the anatomy of the upper respiratory and gastrointestinal tracts, be able to demarcate the surface landmarks of the neck, and be skilled in applying cricoid pressure properly and safely. This article discusses cricoid pressure in the context of safe airway management as well as the perioperative nurse's role as an assistant to the anesthesia professional when applying cricoid pressure.

Rapid sequence induction/intubation controversies

Backgrounds:

Since its first definition and publication on 1970, Rapid Sequence Induction / Intubation (RSI) technique has been accepted globally as the “standard” for doing rapid intubation after induction of anesthesia for patients with high risk of aspiration, especially in emergency situation. However, this technique is not so much a “standard” as there are numerous variations on its practice based on national surveys. Anesthesia providers have their own opinions on the practice of RSI components which need to be discussed to assess their advantages and disadvantages, while there has been no review article which discussed these controversies in the last ten years.

Objectives:

To review the technique differences within RSI protocols.

Methods:

Online databases were searched, including MEDLINE and COCHRANE for each step in the original RSI protocol using keywords such as: “rapid sequence induction” or “rapid sequence intubation” or “RSI” and “controversies” or “head position” or “cricoid pressure” or “neuromuscular blocking agent” or “NMBA” or positive pressure ventilation” or “PPV”; and so on. Articles were then sorted out based on relevancy.

Results and conclusion:

Supported by new evidence, RSI practices may differ in: the positioning of patient, choices of induction agent, application of cricoid pressure, choices of neuromuscular blocking agent, and the use of positive pressure ventilation. A more updated and standardized guideline should be established by referring and evaluating to these controversies.

Effect of Paratracheal Pressure on the Glottic View During Direct Laryngoscopy: A Randomized Double-Blind, Noninferiority Trial

BACKGROUND

Cricoid pressure has been used as a component of the rapid sequence induction and intubation technique. However, concerns have been raised regarding the effectiveness and safety of cricoid pressure. Paratracheal pressure, a potential alternative to cricoid pressure to prevent regurgitation of gastric contents or aspiration, has been studied to be more effective to cricoid pressure in preventing gastric insufflation during positive pressure ventilation. However, to adopt paratracheal compression into our practice, adverse effects including its effect on the glottic view during direct laryngoscopy should be studied. We conducted a randomized, double-blind, noninferiority trial comparing paratracheal and cricoid pressures for any adverse effects on the view during direct laryngoscopy, together with other secondary outcome measures.

METHODS

In total, 140 adult patients undergoing general anesthesia randomly received paratracheal pressure (paratracheal group) or cricoid pressure (cricoid group) during anesthesia induction. The primary end point was the incidence of deteriorated laryngoscopic view, evaluated by modified Cormack-Lehane grade with a predefined noninferiority margin of 15%. Secondary end points included percentage of glottic opening score, ease of mask ventilation, change in ventilation volume and peak inspiratory pressure during mechanical mask ventilation, ease of tracheal intubation, and resistance encountered while advancing the tube into the glottis. The position of the esophagus was assessed by ultrasound in both groups to determine whether pressure applied to the respective area would be likely to result in esophageal compression. All secondary outcomes were tested for superiority, except percentage of glottic opening score, which was tested for noninferiority.

RESULTS

Paratracheal pressure was noninferior to cricoid pressure regarding the incidence of deterioration of modified Cormack-Lehane grade (0% vs 2.9%; absolute risk difference, -2.9%; 95% confidence interval, -9.9 to 2.6, P <.0001). Mask ventilation, measured on an ordinal scale, was found to be easier (ie, more likely to have a lower score) with paratracheal pressure than with cricoid pressure (OR, 0.41; 95% confidence interval, 0.21-0.79; P = .008). The increase in peak inspiratory pressure was significantly less in the paratracheal group than in the cricoid group during mechanical mask ventilation (median [min, max], 0 [-1, 1] vs 0 [-1, 23]; P = .001). The differences in other secondary outcomes were nonsignificant between the groups. The anatomical position of the esophagus was more suitable for compression in the paratracheal region, compared to the cricoid cartilage region.

CONCLUSIONS

Paratracheal pressure was noninferior to cricoid pressure with respect to the effect on glottic view during direct laryngoscopy.

The Knowledge of Health Professionals About the Application of Cricoid Pressure in a Low-Income Country: A Single-Center Survey Study

BACKGROUND

The application of cricoid pressure requires good knowledge and practice of health professionals who are working in operation theatres to prevent pulmonary aspiration. This study aims to assess the application of cricoid pressure knowledge and practice in health professionals who are working in the operation theatres.

METHODS

This survey-based study was conducted in health care professionals who are working in the operation theatre of Debre Tabor Comprehensive Specialized Hospital from November 1 to December 1, 2020. A structured checklist was used to collect data regarding the knowledge and practice of the application of cricoid pressure.

RESULTS

A total of 43 health professionals who are working in the operation theaters were involved in this study with a response rate of 81%. The correct anatomic position of cricoid cartilage was not identified in 67% of nurses. We found that 78% of anesthetists did not use the nasogastric tube for decompression, and 83% of them complain of difficult intubation during the application of cricoid pressure.

CONCLUSION

Health care professionals who are working in operation theatres had poor knowledge and practice in the application of cricoid pressure.

Sellick maneuver assisted real-time to achieve target force range in simulated environment-A prospective observational cross-sectional study on manikin

A force sensor system was developed to give real-time visual feedback on a range of force. In a prospective observational cross-section study, twenty-two anaesthesia nurses applied cricoid pressure at a target range of 30–40 Newtons for 60 seconds in three sequential steps on manikin: Group A (step 1 blinded, no sensor), Group B (step 2 blinded sensor), Group C (step 3 sensor feedback). A weighing scale was placed below the manikin. This procedure was repeated once again at least 1 week apart. The feedback system used 3 different colours to indicate the force range achieved as below target, achieve target, above target. Significantly higher proportion of target cricoid pressure was achieved with the use of sensor feedback in Group C; 85.9% (95%CI: 82.7%-88.7%) compared to when blinded from sensor in Group B; 31.3% (95%CI: 27.4–35.4%). Cricoid force achieved blind (Group B) exceeded force achieved with feedback (Group C) by a mean of 8.0 (95%CI: 5.9–10.2, p<0.0001) and 6.2 (95%CI:4.1–8.3, p< 0.0001) Newtons in round 1 and 2 respectively. Weighing scale read lower than corresponding force sensor by a mean of 8.4 Newtons (95% CI: 7.1–9.7, p<0.0001) in group B and 5.8 Newtons (95% CI: 4.5–7.1, p<0.0001) in Group C. Force sensor visual feedback system enabled application of reproducible target cricoid pressure with less variability and has potential value in clinical use. Using weighing scale to quantify and train cricoid pressure requires a review. Understanding the force applied is the first step to make cricoid pressure a safe procedure.

Cricoid Pressure During Induction for Tracheal Intubation in Critically Ill Children: A Report From National Emergency Airway Registry for Children

OBJECTIVES

Cricoid pressure is often used to prevent regurgitation during induction and mask ventilation prior to high-risk tracheal intubation in critically ill children. Clinical data in children showing benefit are limited. Our objective was to evaluate the association between cricoid pressure use and the occurrence of regurgitation during tracheal intubation for critically ill children in PICU.

DESIGN

A retrospective cohort study of a multicenter pediatric airway quality improvement registry.

SETTINGS

Thirty-five PICUs within general and children's hospitals (29 in the United States, three in Canada, one in Japan, one in Singapore, and one in New Zealand).

PATIENTS

Children (< 18 yr) with initial tracheal intubation using direct laryngoscopy in PICUs between July 2010 and December 2015.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Multivariable logistic regression analysis was used to evaluate the association between cricoid pressure use and the occurrence of regurgitation while adjusting for underlying differences in patient and clinical care factors. Of 7,825 events, cricoid pressure was used in 1,819 (23%). Regurgitation was reported in 106 of 7,825 (1.4%) and clinical aspiration in 51 of 7,825 (0.7%). Regurgitation was reported in 35 of 1,819 (1.9%) with cricoid pressure, and 71 of 6,006 (1.2%) without cricoid pressure (unadjusted odds ratio, 1.64; 95% CI, 1.09-2.47; p = 0.018). On multivariable analysis, cricoid pressure was not associated with the occurrence of regurgitation after adjusting for patient, practice, and known regurgitation risk factors (adjusted odds ratio, 1.57; 95% CI, 0.99-2.47; p = 0.054). A sensitivity analysis in propensity score-matched cohorts showed cricoid pressure was associated with a higher regurgitation rate (adjusted odds ratio, 1.01; 95% CI, 1.00-1.02; p = 0.036).

CONCLUSIONS

Cricoid pressure during induction and mask ventilation before tracheal intubation in the current ICU practice was not associated with a lower regurgitation rate after adjusting for previously reported confounders. Further studies are needed to determine whether cricoid pressure for specific indication with proper maneuver would be effective in reducing regurgitation events.

Ultra-modified rapid sequence induction with transnasal humidified rapid insufflation ventilatory exchange: Challenging convention

During positive pressure ventilation, gastric inflation and subsequent pulmonary aspiration can occur. Rapid sequence induction (RSI) technique is an age-old formula to prevent this. We adopted a novel approach of RSI for patients with high risk of aspiration and evaluated it further in patients undergoing laparoscopic surgeries. We believe that, in patients with risk of gastric insufflation and pulmonary aspiration, transnasal humidified rapid-insufflation ventilatory exchange can be useful in facilitating pre- and apnoeic oxygenation till tracheal isolation is achieved.

Pulmonary aspiration during intubation in a high-risk patient: A video clip and clinical implications

We report a case of pulmonary aspiration during induction of general anesthesia in a patient who was status post esophagectomy. Sudden, unexpected aspiration occurred even though the patient had fasted adequately (over 13 hours) and received rapid sequence anesthesia induction. Since during esophagectomy, the lower esophageal sphincter is excised, stomach vagal innervation is lost, and the stomach is flaccid, draining only by gravity, the patient becomes vulnerable to aspiration. As the incidence of perioperative pulmonary aspiration is relatively low, precautions to prevent aspiration tend to be overlooked. We present a video clip showing pulmonary aspiration and discuss the literature concerning the risk of aspiration and its preventive strategies.

Cricoid Pressure Controversies

Since cricoid pressure was introduced into clinical practice, controversial issues have arisen, including necessity, effectiveness in preventing aspiration, quantifying the cricoid force, and its reliability in certain clinical entities and in the presence of gastric tubes. Cricoid pressure–associated complications have also been alleged, such as airway obstruction leading to interference with manual ventilation, laryngeal visualization, tracheal intubation, placement of supraglottic devices, and relaxation of the lower esophageal sphincter. This review synthesizes available information to identify, address, and attempt to resolve the controversies related to cricoid pressure. The effective use of cricoid pressure requires that the applied force is sufficient to occlude the esophageal entrance while avoiding airway-related complications. Most of these complications are caused by excessive or inadequate force or by misapplication of cricoid pressure. Because a simple-to-use and reliable cricoid pressure device is not commercially available, regular training of personnel, using technology-enhanced cricoid pressure simulation, is required. The current status of cricoid pressure and objectives for future cricoid pressure–related research are also discussed.

Determinants of Success and Failure in Prehospital Endotracheal Intubation

Introduction

This study aimed to identify factors associated with successful endotracheal intubation (ETI) by a multisite emergency medical services (EMS) agency.

Methods

We collected data from the electronic prehospital record for all ETI attempts made from January through May 2010 by paramedics and other EMS crew members at a single multistate agency. If documentation was incomplete, the study team contacted the paramedic. Paramedics use the current National Association of EMS Physicians definition of an ETI attempt (laryngoscope blade entering the mouth). We analyzed patient and EMS factors affecting ETI.

Results

During 12,527 emergent ambulance responses, 200 intubation attempts were made in 150 patients. Intubation was successful in 113 (75%). A crew with paramedics was more than three times as likely to achieve successful intubation as a paramedic/emergency medical technician-Basic crew (odds ratio [OR], 3.30; p=0.03). A small tube (≤7.0 inches) was associated with a more than 4-fold increased likelihood of successful ETI compared with a large tube (≥7.5 inches) (OR, 4.25; p=0.01). After adjustment for these features, compared with little or no view of the glottis, a partial or entire view of the glottis was associated with a nearly 13-fold (OR, 12.98; p=0.001) and a nearly 40-fold (OR, 39.78; p<0.001) increased likelihood of successful intubation, respectively.

Conclusion

Successful ETI was more likely to be accomplished when a paramedic was partnered with another paramedic, when some or all of the glottis was visible and when a smaller endotracheal tube was used.

Analysis of cricoid pressure application: anaesthetic trainee doctors vs. nursing anaesthetic assistants

BACKGROUND AND OBJECTIVE

To evaluate the ability of anaesthetic trainee doctors compared to nursing anaesthetic assistants in identifying the cricoid cartilage, applying the appropriate cricoid pressure and producing an adequate laryngeal inlet view.

METHODS

Eighty-five participants, 42 anaesthetic trainee doctors and 43 nursing anaesthetic assistants, were asked to complete a set of questionnaires which included the correct amount of force to be applied to the cricoid cartilage. They were then asked to identify the cricoid cartilage and apply the cricoid pressure on an upper airway manikin placed on a weighing scale, and the pressure was recorded. Subsequently they applied cricoid pressure on actual anaesthetized patients following rapid sequence induction. Details regarding the cricoid pressure application and the Cormack-Lehane classification of the laryngeal view were recorded.

RESULTS

The anaesthetic trainee doctors were significantly better than the nursing anaesthetic assistants in identifying the cricoid cartilage (95.2% vs. 55.8%, p=0.001). However, both groups were equally poor in the knowledge about the amount of cricoid pressure force required (11.9% vs. 9.3% respectively) and in the correct application of cricoid pressure (16.7% vs. 20.9% respectively). The three-finger technique was performed by 85.7% of the anaesthetic trainee doctors and 65.1% of the nursing anaesthetic assistants (p=0.03). There were no significant differences in the Cormack-Lehane view between both groups.

CONCLUSION

The anaesthetic trainee doctors were better than the nursing anaesthetic assistants in cricoid cartilage identification but both groups were equally poor in their knowledge and application of cricoid pressure.

[Analysis of cricoid pressure application: anaesthetic trainee doctors vs. nursing anaesthetic assistants]

BACKGROUND AND OBJECTIVE

To evaluate the ability of anaesthetic trainee doctors compared to nursing anaesthetic assistants in identifying the cricoid cartilage, applying the appropriate cricoid pressure and producing an adequate laryngeal inlet view.

METHODS

Eighty-five participants, 42 anaesthetic trainee doctors and 43 nursing anaesthetic assistants, were asked to complete a set of questionnaires which included the correct amount of force to be applied to the cricoid cartilage. They were then asked to identify the cricoid cartilage and apply the cricoid pressure on an upper airway manikin placed on a weighing scale, and the pressure was recorded. Subsequently they applied cricoid pressure on actual anaesthetized patients following rapid sequence induction. Details regarding the cricoid pressure application and the Cormack-Lehane classification of the laryngeal view were recorded.

RESULTS

The anaesthetic trainee doctors were significantly better than the nursing anaesthetic assistants in identifying the cricoid cartilage (95.2% vs. 55.8%, p=0.001). However, both groups were equally poor in the knowledge about the amount of cricoid pressure force required (11.9% vs. 9.3% respectively) and in the correct application of cricoid pressure (16.7% vs. 20.9% respectively). The three-finger technique was performed by 85.7% of the anaesthetic trainee doctors and 65.1% of the nursing anaesthetic assistants (p=0.03). There were no significant differences in the Cormack-Lehane view between both groups.

CONCLUSION

The anaesthetic trainee doctors were better than the nursing anaesthetic assistants in cricoid cartilage identification but both groups were equally poor in their knowledge and application of cricoid pressure.

Acute respiratory failure and mechanical ventilation in pregnant patient: A narrative review of literature

Physiological changes of pregnancy imposes higher risk of acute respiratory failure (ARF) with even a slight insult and remains an important cause of maternal and fetal morbidity and mortality. Although pregnant women have different respiratory physiology and different causes of ARF, guidelines specific to ventilatory settings, goals of oxygenation and weaning process could not be framed due to lack of large-scale randomized controlled trials. During the 2009 H1N1 pandemic, pregnant women had higher morbidity and mortality compared to nonpregnant women. During this period, alternative strategies of ventilation such as high-frequency oscillatory ventilation, inhalational of nitric oxide, prone positioning, and extra corporeal membrane oxygenation were increasingly used as a desperate measure to rescue pregnant patients with severe hypoxemia who were not improving with conventional mechanical ventilation. This article highlights the causes of ARF and recent advances in invasive, noninvasive and alternative strategies of ventilation used during pregnancy.

Rapid sequence induction has no use in pediatric anesthesia

(Classic) rapid sequence induction and intubation (RSII) has been considered fundamental to the provision of safe anesthesia. This technique consists of a combination of drugs and techniques and is intended to prevent pulmonary aspiration of gastric content with catastrophic outcomes to the patient. This review investigates aspects of this technique and highlights dangers and frauds if this technique is transferred directly into pediatric anesthesia practice. The author recommends a controlled anesthesia induction by trained pediatric anesthesiologist with suitable equipment for the children considered at risk of pulmonary aspiration. RSSI is a dangerous technique if adopted without modification into pediatric anesthesia and has in its 'classic' form no use.

Comparison of the Macintosh, McCoy, Airtraq laryngoscopes and the intubating laryngeal mask airway in a difficult airway with manual in-line stabilisation: a cross-over simulation-based study

CONTEXT

Patients with multisystem trauma undergoing intubation with manual in-line stabilisation (MILS) have a higher incidence of difficult or failed intubations.

OBJECTIVE

To compare the effectiveness of the Macintosh laryngoscope with three other intubating devices in a high fidelity simulation model.

DESIGN

Cross-over, simulation-based study.

SETTING

Tertiary referral and level 1 trauma centre between June and November 2011.

PARTICIPANTS

Thirty-five experienced airway physicians.

INTERVENTION

Each participant performed tracheal intubations on a Laerdal SimMan manikin in both a normal airway and a difficult airway scenario with MILS. The devices utilised in a randomised order were the Macintosh, McCoy, Airtraq laryngoscopes and the intubating laryngeal mask airway (iLMA).

MAIN OUTCOME MEASURES

The primary outcome was time to intubation. Success rates, grade of laryngoscopy and force of intubation were also measured.

RESULTS

One hundred and forty intubations were attempted by 35 participants in both the normal and MILS scenarios. In the normal airway, there was no difference in success rates and time to intubation. In the difficult airway with MILS, there was no difference in success rates. However, the Airtraq was associated with a longer time to intubation than the Macintosh, McCoy and iLMA, 39.3, 26.7, 23.3, 39.3, 22.8 s, respectively (P < 0.0001). The Airtraq delivered the best glottic view and lowest force of intubation in both scenarios (P < 0.0001), but was associated with the only failed intubation in the study. The McCoy was associated with a significant improvement in the glottic visualisation (P < 0.05) and reduction in the force of intubation (P <0.0001) compared with the Macintosh.

CONCLUSION

In this manikin study, the McCoy demonstrated multiple advantages over the Macintosh. The iLMA was associated with the fastest time to intubation and minimum force of insertion.

Development of a standard operating procedure and checklist for rapid sequence induction in the critically ill

INTRODUCTION

Rapid sequence induction (RSI) of critically ill patients outside of theatres is associated with a higher risk of hypoxia, cardiovascular collapse and death. In the prehospital and military environments, there is an increasing awareness of the benefits of standardised practice and checklists.

METHODS

We conducted a non-systematic review of literature pertaining to key components of RSI preparation and management. A standard operating procedure (SOP) for in-hospital RSI was developed based on this and experience from large teaching hospital anaesthesia and critical care departments.

RESULTS

The SOP consists of a RSI equipment set-up sheet, pre-RSI checklist and failed airway algorithm. The SOP should improve RSI preparation, crew resource management and first pass intubation success while minimising adverse events.

CONCLUSION

Based on the presented literature, we believe the evidence is sufficient to recommend adoption of the core components in the suggested SOP. This standardised approach to RSI in the critically ill may reduce the current high incidence of adverse events and hopefully improve patient outcomes.

Cricoid pressure: Where do we stand?

In 1961, Sellick popularized the technique of cricoid pressure (CP) to prevent regurgitation of gastric contents during anesthesia induction. In the last two decades, clinicians have begun to question the efficacy of CP and therefore the necessity of this maneuver. Some have suggested abandoning it on the grounds that this maneuver is unreliable in producing midline esophageal compression. Moreover, it has been found that application of CP makes tracheal intubation and mask ventilation difficult and induces relaxation of the lower esophageal sphincter. There have also been reports of regurgitation of gastric contents and aspiration despite CP. Further, its effectiveness has been demonstrated only in cadavers; therefore, its efficacy lacks scientific validation. These concerns with the use of CP in modern anesthesia practice have been briefly reviewed in this article.

Rapid-sequence intubation and cricoid pressure

Airway management is the most important clinical skill for anesthesiologist, emergency physician, and other providers who are involved in oxygenation and ventilation of the lungs. Rapid-sequence intubation is the preferred method to secure airway in patients who are at risk for aspiration because it results in rapid unconsciousness (induction) and neuromuscular blockade (paralysis). Application of cricoid pressure (CP) for patients undergoing rapid-sequence intubation is controversial. Multiple specialty societies have recommended that CP is not effective in preventing aspiration; rather it may worsen laryngoscopic view and impair bag-valve mask ventilation. Some experts think that CP should be applied in trauma and patients at risk for aspiration; however CP, if necessary, should be altered or removed to facilitate intubation.

Gastric tubes and airway management in patients at risk of aspiration: history, current concepts, and proposal of an algorithm

Rapid sequence induction and intubation (RSII) and awake tracheal intubation are commonly used anesthetic techniques in patients at risk of pulmonary aspiration of gastric or esophageal contents. Some of these patients may have a gastric tube (GT) placed preoperatively. Currently, there are no guidelines regarding which patient should have a GT placed before anesthetic induction. Furthermore, clinicians are not in agreement as to whether to keep a GT in situ, or to partially or completely withdraw it before anesthetic induction. In this review we provide a historical perspective of the use of GTs during anesthetic induction in patients at risk of pulmonary aspiration. Before the introduction of cricoid pressure (CP) in 1961, various techniques were used including RSII combined with a head-up tilt. Sellick initially recommended the withdrawal of the GT before anesthetic induction. He hypothesized that a GT increases the risk of regurgitation and interferes with the compression of the upper esophagus during CP. He later modified his view and emphasized the safety of CP in the presence of a GT. Despite subsequent studies supporting the effectiveness of CP in occluding the esophagus around a GT, Sellick's early view has been perpetuated by investigators who recommend partial or complete withdrawal of the GT. On the basis of available information, we have formulated an algorithm for airway management in patients at risk of aspiration of gastric or esophageal contents. The approach in an individual patient depends on: the procedure; type and severity of the underlying pathology; state of consciousness; likelihood of difficult airway; whether or not the GT is in place; contraindications to the use of RSII or CP. The algorithm calls for the preanesthetic use of a large-bore GT to remove undigested food particles and awake intubation in patients with achalasia, and emptying the pouch by external pressure and avoidance of a GT in patients with Zenker diverticulum. It also stipulates that in patients with gastric distension without predictable airway difficulties, a clinical and imaging assessment will determine the need for a GT and in severe cases an attempt to insert a GT should be made. In the latter cases, the success of placement will indicate whether to use RSII or awake intubation. The GT should not be withdrawn and should be connected to suction during induction. Airway management and the use of GTs in the surgical correction of certain gastrointestinal anomalies in infants and children are discussed.

The difficult airway with recommendations for management--part 2--the anticipated difficult airway

BACKGROUND

Appropriate planning is crucial to avoid morbidity and mortality when difficulty is anticipated with airway management. Many guidelines developed by national societies have focused on management of difficulty encountered in the unconscious patient; however, little guidance appears in the literature on how best to approach the patient with an anticipated difficult airway.

METHODS

To review this and other subjects, the Canadian Airway Focus Group (CAFG) was re-formed. With representation from anesthesiology, emergency medicine, and critical care, CAFG members were assigned topics for review. As literature reviews were completed, results were presented and discussed during teleconferences and two face-to-face meetings. When appropriate, evidence- or consensus-based recommendations were made, and levels of evidence were assigned.

PRINCIPAL FINDINGS

Previously published predictors of difficult direct laryngoscopy are widely known. More recent studies report predictors of difficult face mask ventilation, video laryngoscopy, use of a supraglottic device, and cricothyrotomy. All are important facets of a complete airway evaluation and must be considered when difficulty is anticipated with airway management. Many studies now document the increasing patient morbidity that occurs with multiple attempts at tracheal intubation. Therefore, when difficulty is anticipated, tracheal intubation after induction of general anesthesia should be considered only when success with the chosen device(s) can be predicted in a maximum of three attempts. Concomitant predicted difficulty using oxygenation by face mask or supraglottic device ventilation as a fallback makes an awake approach advisable. Contextual issues, such as patient cooperation, availability of additional skilled help, and the clinician's experience, must also be considered in deciding the appropriate strategy.

CONCLUSIONS

With an appropriate airway evaluation and consideration of relevant contextual issues, a rational decision can be made on whether an awake approach to tracheal intubation will maximize patient safety or if airway management can safely proceed after induction of general anesthesia. With predicted difficulty, close attention should be paid to details of implementing the chosen approach. This should include having a plan in case of the failure of tracheal intubation or patient oxygenation.

How much and where: assessment of knowledge level of the application of cricoid pressure

INTRODUCTION

Application of cricoid pressure is a frequently used technique in both rapid sequence intubation in multiple settings and in a more controlled setting in the operating room. In a survey of emergency department personnel performed at the University of Michigan, it was found that there is a knowledge deficit in the recommended force and the anatomic localization of cricoid pressure. Participants in the original study, which included emergency nurses, medical residents, and attending physicians, rated their training in cricoid pressure as poor or nonexistent. A review of the literature shows that, although cricoid pressure is used during endotracheal intubation to protect against regurgitation of gastric contents, many people applying cricoid pressure do not have a good knowledge of where to apply the pressure or how much pressure to apply to be effective. Because cricoid pressure is applicable in areas other than the emergency department, our study surveys personnel in emergency medical services/flight crew; emergency, intensive care unit, and operating room nurses; and respiratory therapists. Even though the use of cricoid pressure is no longer recommended, it is still routinely used. Although applying cricoid pressure is a simple procedure, persons using it must be thoroughly trained and retrained to prevent complications.

METHODS

When we replicated the University of Michigan study at a 254-bed tertiary care facility, a potential of 325 staff members were given access to an online survey using the questions in the original survey. Staff were assigned to a HealthStream module and sent an invitation through their employee e-mail account. The module included a link to the questionnaire, and demographic data were gathered. The module was optional and results confidential.

RESULTS

Operating room nurses were most likely to receive supervised instruction on anesthetized patients. These operating room nurses also showed the highest overall knowledge level about the application technique of cricoid pressure.

DISCUSSION

There continues to be a lack of knowledge about the application of cricoid pressure during intubation. There is an opportunity for collaboration between staff and academic educators to allow for additional theoretical as well as hands-on practice.

Effectiveness of cricoid pressure in preventing gastric aspiration during rapid sequence intubation in the emergency department: study protocol for a randomised controlled trial

Background

Cricoid pressure is considered to be the gold standard means of preventing aspiration of gastric content during Rapid Sequence Intubation (RSI). Its effectiveness has only been demonstrated in cadaveric studies and case reports. No randomised controlled trials comparing the incidence of gastric aspiration following emergent RSI, with or without cricoid pressure, have been performed. If improperly applied, cricoid pressure increases risk to the patient. The clinical significance of aspiration in the emergency department is unknown. This randomised controlled trial aims to; 1. Compare the application of the 'ideal" amount of force (30 - 40 newtons) to standard, unmeasured cricoid pressure and 2. Determine the incidence of clinically defined aspiration syndromes following RSI using a fibrinogen degradation assay previously described.

Methods/design

212 patients requiring emergency intubation will be randomly allocated to either control (unmeasured cricoid pressure) or intervention groups (30 - 40 newtons cricoid pressure). The primary outcome is the rate of aspiration of gastric contents (determined by pepsin detection in the oropharyngeal/tracheal aspirates or treatment for aspiration pneumonitis up to 28 days post-intubation). Secondary outcomes are; correlation between aspiration and lowest pre-intubation Glasgow Coma Score, the relationship between detection of pepsin in trachea and development of aspiration syndromes, complications associated with intubation and grade of the view on direct largyngoscopy.

Discussion

The benefits and risks of cricoid pressure application will be scrutinised by comparison of the incidence of aspiration and difficult or failed intubations in each group. The role of cricoid pressure in RSI in the emergency department and the use of a pepsin detection as a predictor of clinical aspiration will be evaluated.

Trial registration

Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12611000587909

Preoxygenation and prevention of desaturation during emergency airway management

Patients requiring emergency airway management are at great risk of hypoxemic hypoxia because of primary lung pathology, high metabolic demands, anemia, insufficient respiratory drive, and inability to protect their airway against aspiration. Tracheal intubation is often required before the complete information needed to assess the risk of periprocedural hypoxia is acquired, such as an arterial blood gas level, hemoglobin value, or even a chest radiograph. This article reviews preoxygenation and peri-intubation oxygenation techniques to minimize the risk of critical hypoxia and introduces a risk-stratification approach to emergency tracheal intubation. Techniques reviewed include positioning, preoxygenation and denitrogenation, positive end expiratory pressure devices, and passive apneic oxygenation.

Cricoid pressure: a review of the literature

Aspiration pneumonitis (Mendelson's syndrome) is universally accepted as a complication of general anaesthesia. According to Ellis et al (2007) death from aspiration was first described by Simpson in 1848, and it was not until 1946 that Mendelson identified acid aspiration in a significant number of obstetric patients undergoing facemask anaesthesia. The advent of techniques to secure the airway, through the use of airway adjuncts has gone some way to reduce the likely incidence of aspiration in today's perioperative arena. The positive outcome for patients is corroborated by Neilipovitz & Crosby (2007) who report aspiration as a rare complication with an overall incidence of 1:2,000-3,000. As Ewart (2007) highlights, Mendelson's syndrome is due to pharmacological effects at a molecular level which occur in the airway tissues and are caused by the use of induction and neuromuscular blocking agents. The resultant loss of consciousness and consequent diminished protective airway reflexes ultimately places the patient at risk until their airway is secured. Preventative measures to protect the lung from contamination with gastric contents, for example preoperative fasting, are therefore instigated prior to securing the airway.

The use of ProSeal laryngeal mask airway in caesarean section--experience in 3000 cases

Rapid sequence induction is currently the recommended technique in general anaesthesia for caesarean section. However, the usefulness of the ProSeal laryngeal mask airway as a rescue airway in the event of difficult or failed intubation has been recognised in numerous case reports. In this study, we report the experience of the use of the ProSeal laryngeal mask in 3000 elective caesarean sections in a single centre, using a method of insertion that allows a rapid establishment of a patent airway together with gastric drainage.

Scandinavian clinical practice guidelines on general anaesthesia for emergency situations

Emergency patients need special considerations and the number and severity of complications from general anaesthesia can be higher than during scheduled procedures. Guidelines are therefore needed. The Clinical Practice Committee of the Scandinavian Society of Anaesthesiology and Intensive Care Medicine appointed a working group to develop guidelines based on literature searches to assess evidence, and a consensus meeting was held. Consensus opinion was used in the many topics where high-grade evidence was unavailable. The recommendations include the following: anaesthesia for emergency patients should be given by, or under very close supervision by, experienced anaesthesiologists. Problems with the airway and the circulation must be anticipated. The risk of aspiration must be judged for each patient. Pre-operative gastric emptying is rarely indicated. For pre-oxygenation, either tidal volume breathing for 3 min or eight deep breaths over 60 s and oxygen flow 10 l/min should be used. Pre-oxygenation in the obese patients should be performed in the head-up position. The use of cricoid pressure is not considered mandatory, but can be used on individual judgement. The hypnotic drug has a minor influence on intubation conditions, and should be chosen on other grounds. Ketamine should be considered in haemodynamically compromised patients. Opioids may be used to reduce the stress response following intubation. For optimal intubation conditions, succinylcholine 1-1.5 mg/kg is preferred. Outside the operation room, rapid sequence intubation is also considered the safest method. For all patients, precautions to avoid aspiration and other complications must also be considered at the end of anaesthesia.

A controlled rapid-sequence induction technique for infants may reduce unsafe actions and stress

BACKGROUND

Classic rapid-sequence induction of anaesthesia (RSI-classic) in infants and small children presents a time-critical procedure, regularly associated with hypoxia. This results in high stress levels for the provider and may trigger unsafe actions. Hence, a controlled induction technique (RSI-controlled) that involves gentle mask ventilation until full non-depolarizing muscular blockade has become increasingly popular. Clinical observation suggests that RSI-controlled may reduce the adverse effects noted above. We aimed to evaluate both techniques with respect to unsafe actions and stress.

METHODS

In this controlled, randomized simulator-based study, 30 male trainees and specialists in anaesthesiology performed a simulated anaesthesia induction in a 4-week-old infant with pyloric stenosis. Two different RSI techniques, classic and controlled, were applied to 15 candidates each. We recorded the incidence of hypoxaemia, forced mask ventilation, and intubation difficulties. In addition, we measured individual stress levels by ergospirometry, salivary cortisol, and alpha-amylase, as well as a post-trial questionnaire.

RESULTS

Hypoxaemia always occurred in RSI-classic but not in RSI-controlled, repeatedly resulting in unsafe actions. Subjective stress perception and some objective stress levels were lower in the volunteers performing RSI-controlled.

CONCLUSIONS

Our data suggest that RSI-controlled, as compared with RSI-classic, leads to fewer unsafe actions and may reduce individual stress levels.