Cricoid pressure decreases ease of tracheal intubation using fibreoptic laryngoscopy (WuScope System

Spanish Society of Anesthesiology, Reanimation and Pain Therapy (SEDAR), Spanish Society of Emergency and Emergency Medicine (SEMES) and Spanish Society of Otolaryngology, Head and Neck Surgery (SEORL-CCC) Guideline for difficult airway management. Part I

The Airway Management section of the Spanish Society of Anesthesiology, Resuscitation, and Pain Therapy (SEDAR), the Spanish Society of Emergency Medicine (SEMES), and the Spanish Society of Otorhinolaryngology and Head and Neck Surgery (SEORL-CCC) present the Guide for the comprehensive management of difficult airway in adult patients. Its principles are focused on the human factors, cognitive processes for decision-making in critical situations, and optimization in the progression of strategies application to preserve adequate alveolar oxygenation in order to enhance safety and the quality of care. The document provides evidence-based recommendations, theoretical-educational tools, and implementation tools, mainly cognitive aids, applicable to airway management in the fields of anesthesiology, critical care, emergencies, and prehospital medicine. For this purpose, an extensive literature search was conducted following PRISMA-R guidelines and was analyzed using the GRADE methodology. Recommendations were formulated according to the GRADE methodology. Recommendations for sections with low-quality evidence were based on expert opinion through consensus reached via a Delphi questionnaire.

The Clinical Use of Cricoid Pressure: First, Do No Harm

Application of cricoid pressure (CP) during rapid sequence induction and intubation sequence has been a "standard" of care for many decades, despite limited scientific proof of its efficacy in preventing pulmonary aspiration of gastric contents. While some of the current rapid sequence induction and intubation guidelines recommend its use, other international guidelines do not, and many clinicians argue that there is insufficient evidence to either continue or abandon its use. Recently published articles and accompanying editorials have reignited the debate on the efficacy and safety of CP application and have generated multiple responses that pointed out the various (and significant) limitations of the available evidence. Thus, a critical discussion of available data must be undertaken before making a final clinical decision on such an important patient safety issue. In this review, the authors will take an objective look at the available scientific evidence about the effectiveness and safety of CP in patients at risk of pulmonary aspiration of gastric contents. We suggest that current data are inadequate to impose clinical guidelines on the use of CP because we acknowledge that currently there is not, and there may never be, a method to prevent aspiration in all patients. In addition, we reiterate that a universally accepted medical-legal standard for approaching the high-risk aspiration patient does not exist, discuss the differences in practice between the US and international practitioners regarding use of CP, and propose 5 recommendations on how future studies might be designed to obtain optimal scientific evidence about the effectiveness and safety of CP in patients at risk for pulmonary aspiration.

The effect of cricoid pressure on tracheal intubation in adult patients: a systematic review and meta-analysis

PURPOSE

This meta-analysis aimed to assess the impact of cricoid pressure (CP) application on intubation outcomes.

SOURCE

Electronic databases (i.e., MEDLINE, PubMed, Embase, and Cochrane review) were searched from inception to 2 June 2020 for randomized-controlled trials that assessed the intubation outcomes in adult patients using laryngoscopic approaches with and without the application of CP (i.e., CP vs non-CP group). The primary outcome was the successful first-attempt intubation rate (SFAIR), and the secondary outcomes were intubation time, incidences of poor laryngoscopic views (i.e., Cormack and Lehane grade 3-4), airway complications, and pulmonary aspiration.

PRINCIPAL FINDINGS

A total of five trials (published from 2005 to 2018) were included, and all tracheal intubations were performed by anesthesiologists or nurse anesthetists with a video (n = 3) or Macintosh laryngoscope (n = 2) in the operating room. We found no significant difference in SFAIR (risk ratio [RR], 0.98; P = 0.37), incidence of poor laryngoscopic views (RR, 1.49; P = 0.21), and risk of sore throat (RR, 1.17; P = 0.73) between the two groups. Nevertheless, the intubation time on the first successful attempt was slightly longer (weighted mean difference = 4.40 sec, P = 0.002) and risk of hoarseness was higher (RR, 1.70; P = 0.03) in the CP group compared with in the non-CP group. The secondary outcome "pulmonary aspiration" was not analyzed because only one trial was available.

CONCLUSION

The application of CP did not have a negative impact on the SFAIR or laryngoscopic view. Nevertheless, this maneuver may slightly prolong intubation time and increase the risk of postoperative hoarseness.

Effect of Cricoid Pressure on Laryngeal View During Macintosh, McGrath MAC X-Blade and GlideScope Video Laryngoscopies

Objective

Cricoid pressure is useful in fasted patients requiring emergency intubation. We compared the effect of cricoid pressure on laryngeal view during Macintosh, McGrath MAC X-Blade and GlideScope video laryngoscopy.

Methods

After obtaining approval from the Human Research Ethics Committee and written informed consent from patients, we enrolled 120 patients (American Society of Anesthesiologists I-II, age 18-65 years) undergoing elective surgery that required endotracheal intubation in this prospective randomised study. Patients were divided into three groups (Macintosh, McGrath MAC X-Blade and GlideScope).

Results

Demographic and airway variables were similar in the groups. Cormack-Lehane grades were improved or unchanged on using cricoid pressure in Macintosh and McGrath MAC X-Blade groups. However, laryngeal views worsened in 12 patients (30%), remained unchanged in 26 patients (65%) and improved in 2 patients (5%) in the GlideScope group (p<0.001). Insertion and intubation times for Macintosh and McGrath MAC X-Blade video laryngoscopes were similar. Insertion times for GlideScope and Macintosh video laryngoscopes were similar, but were longer than those for the McGrath MAC X-Blade video laryngoscope (p=0.02). Tracheal intubation took longer with the GlideScope video laryngoscope than with the other devices (p<0.001 and p=0.003). Mean arterial pressures after insertion increased significantly in Macintosh and GlideScope groups (p=0.004 and p=0.001, respectively) compared with post-induction values. Heart rates increased after insertion in all three groups compared with post-induction values (p<0.001). Need for optimisation manoeuvres and postoperative minor complications were comparable in all three groups.

Conclusion

Although all three devices are useful for normal or difficult intubation, cricoid pressure improved Cormack-Lehane grades of Macintosh and McGrath MAC X-Blade video laryngoscopes but statistically significantly worsened that of the GlideScope video laryngoscope.

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.

The performance of neck circumference and other airway assessment tests for the prediction of difficult intubation in obese parturients undergoing cesarean delivery

BACKGROUND

Pregnancy and obesity each increase the chance of difficult tracheal intubation. This study assessed the performance of the neck circumference and other bedside tests in predicting difficult intubation, and aimed to identify the optimal cutoff point of the test(s) with the highest performance.

METHODS

Parturients with a body mass index ≥30kg/m², undergoing a cesarean delivery employing conventional tracheal intubation, were enrolled. Preoperative neck circumference, sternomental distance and modified Mallampati test were examined. Difficult intubation was defined as intubation difficulty scale score ≥5.

RESULTS

Five hundred and seventy parturients of mean body mass index 34.1 (±SD 3.8) kg/m² were recruited. The incidence of difficult intubation was 3.5%. The performance of the neck circumference test, conducted with the patient sitting or supine, and using the area under the receiver operating characteristic (ROC) curves, was 0.6 (95% CI 0.5 to 0.7) and 0.6 (95% CI 0.4 to 0.7) respectively. The area under the ROC for the modified Mallampati test was 0.6 (95% CI 0.5 to 0.7) and for the sternomental distance test was 0.7 (95% CI 0.6 to 0.8). A sternomental distance less than 14.5cm, and a ratio of neck circumference in the sitting position to sternomental distance of greater than or equal to 2.7, were optimal cutoff points to identify difficult intubation.

CONCLUSION

The neck circumference, the sternomental distance, the modified Mallampati test and the ratio of neck circumference to the sternomental distance show limited performance as screening tests to predict difficult intubation among obese parturients.

Effectiveness and risks of cricoid pressure during rapid sequence induction for endotracheal intubation

BACKGROUND

Rapid sequence induction (RSI) for endotracheal intubation is a technique widely used in anaesthesia, emergency and intensive care medicine to secure an airway in patients deemed at risk of pulmonary aspiration. Cricoid pressure is conceptually used to reduce the risk of aspiration by compressing the oesophagus.

OBJECTIVES

To identify and evaluate all randomized controlled trials (RCTs) involving participants undergoing elective or emergency airway management via RSI and compare participants who have cricoid pressure administered with participants who do not have cricoid pressure administered.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2015, Issue 4), MEDLINE via OvidSP (1946 to May 2015), EMBASE via OvidSP (1980 to May 2015), ISI Web of Science (from 1940 to May 2015) and CINAHL via EBSCOhost (1982 to May 2015).

SELECTION CRITERIA

We included all RCTs comparing people undergoing RSI who have cricoid pressure applied, either intermittently or continuously, with people undergoing RSI who do not have cricoid pressure applied in the context of endotracheal intubation using a direct laryngoscopic technique. We included both elective and emergency cases. We included studies of blinded and unblinded participants. Participants (male or female) were involved in any type of procedure where general anaesthetic utilizing RSI or emergency airway management utilizing RSI and endotracheal intubation was undertaken. We expected the control arm to be the absence of cricoid pressure at any stage during RSI. The primary outcome of interest was the reported event rate or prevalence of aspiration determined by a) documented gastric aspiration determined by visual inspection of aspirated stomach contents on laryngoscopy; b) pepsin detection in tracheal aspirate using the Ufberg method; c) post-anaesthetic radiographic changes suggestive of aspiration pneumonitis or d) any combination of a to c. Secondary outcomes of interest included documented impaired visualization of the airway by a treating laryngoscopist, force applied during cricoid pressure, the direction of application of force of applied cricoid pressure, independent risk factors for aspiration and whether the person applying cricoid pressure had previously done so in an emergency airway context.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the titles and abstracts of all the studies obtained from the search using recognition of words such as 'cricoid pressure', 'rapid sequence intubation', 'emergency airway management' and 'aspiration'. Two authors independently determined the study inclusion by using a study eligibility form that we developed for the purpose of this review. We also reported the decisions regarding inclusion and exclusion in accordance with the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement. We assumed that studies that did not describe the use of RSI in their title, abstract or methodology used an alternative method of anaesthetic induction or emergency airway management and thus we excluded them. Data extracted from included studies comprised study characteristics, participant demographics, intervention and comparison details plus outcome measures and results. We contacted primary authors of studies with missing or unreported but potentially relevant data to obtain missing data.

MAIN RESULTS

Of 493 records that we identified from databases as a result of the search (excluding duplicates), we regarded 70 abstracts/titles as potentially relevant studies. Independent scrutiny of these 70 titles and abstracts identified 29 potentially relevant studies. Of the 29 potentially relevant studies, one study met the criteria for inclusion. This study was a RCT that compared participants undergoing RSI and endotracheal intubation in the context of elective surgery requiring a general anaesthetic. Forty participants were recruited, 20 of whom had cricoid pressure applied and 20 of whom had cricoid pressure simulated. The main outcomes reported were systolic arterial pressure and heart rate after laryngoscopy and tracheal intubation. We did not consider these outcomes relevant for the purposes of this systematic review. The search also identified one study that could potentially be included in an updated systematic review in the future, but was at the time of the search a proposal for a trial only and had no reported outcomes at this time.

AUTHORS' CONCLUSIONS

There is currently no information available from published RCTs on clinically relevant outcome measures with respect to the application of cricoid pressure during RSI in the context of endotracheal intubation. On the basis of the findings of non-RCT literature, however, cricoid pressure may not be necessary to undertake RSI safely, and therefore well-designed and conducted RCTs should nonetheless be encouraged to properly assess the safety and effectiveness of cricoid pressure.

Cardiac Arrest Resuscitation

Cardiac arrest is a dynamic disease that tests the multitasking and leadership abilities of emergency physicians. Providers must simultaneously manage the logistics of resuscitation while searching for the cause of cardiac arrest. The astute clinician will also realize that he or she is orchestrating only one portion of a larger series of events, each of which directly affects patient outcomes. Resuscitation science is rapidly evolving, and emergency providers must be familiar with the latest evidence and controversies surrounding resuscitative techniques. This article reviews evidence, discusses controversies, and offers strategies to provide quality cardiac arrest resuscitation.

The duration of fibre-optic intubation is increased by cricoid pressure. A randomised double-blind study

BACKGROUND

In some categories of patients, a rapid sequence induction using a fibre-optic method may be indicated. The aim of the present study was to examine the effect of cricoid pressure (CP) on the duration of fibre-optic intubation. The hypothesis was that CP would prolong the intubation time.

METHODS

The study was a randomised, double-blind, cross-over study. The patients were intubated twice, in a randomised way, using a flexible fibrescope once with and once without CP. The intubation time and the visualisation of the glottis were registered. If the intubation was not completed within 180 s, it was registered as failed. CP was standardised to a pressure of 30 N. The data are given as the mean (standard deviation) or median [interquartile] (range).

RESULTS

Fifty patients were included, with a mean age of 53 years (14.6) and mean body mass index of 26.4 (4.3). Three intubations without and 13 intubations with CP failed. The durations of intubation without and with CP were 59 s [53-79 s] (34-144 s) and 75 s [67-104 s] (43-179 s), respectively (P < 0.001).

CONCLUSION

The study showed that CP prolongs the duration of fibre-optic intubation in patients with Mallampati grades 1-2.

Update on cardiopulmonary resuscitation guidelines of interest to anesthesiologists

BACKGROUND AND OBJECTIVES

The new cardiopulmonary resuscitation (CPR) guidelines emphasize the importance of high-quality chest compressions and modify some routines. The objective of this report was to review the main changes in resuscitation practiced by anesthesiologists.

CONTENTS

The emphasis on high-quality chest compressions with adequate rate and depth allowing full recoil of the chest and with minimal interruptions is highlighted in this update. One should not take more than ten seconds checking the pulse before starting CPR. The universal relationship of 30:2 is maintained, modifying its order, initiating with chest compressions, followed by airways and breathing (C-A-B instead of A-B-C). The procedure "look, listen, and feel whether the patient is breathing" was removed from the algorithm, and the use of cricoid pressure during ventilations is not recommended any more. The rate of chest compressions was changed for at least one hundred per minute instead of approximately one hundred per minute, and its depth in adults was changed to 5 cm instead of the prior recommendation of 4 to 5 cm. The single shock is maintained, and it should be of 120 to 200 J when it is biphasic; and 360 J when it is monophasic. In advanced cardiac life support, the use of capnography and capnometry to confirm intubation and monitoring the quality of CPR is a formal recommendation. Atropine is no longer recommended for routine use in the treatment of pulseless electrical activity or asystole.

CONCLUSIONS

Updating the phases of the new CPR guidelines is important, and continuous learning is recommended. This will improve the quality of resuscitation and survival of patients in cardiac arrest.

Teaching anaesthetic nurses optimal force for effective cricoid pressure: a literature review

AIMS AND OBJECTIVES

This literature review explores the role of force and education in cricoid pressure, an essential aspect of practice for any nurse within a critical care environment.

BACKGROUND

Cricoid pressure is utilized in everyday practice during rapid sequence induction (RSI) of anaesthesia. The purpose of cricoid pressure is to occlude the oesophagus in order to reduce the risk of acid aspiration during emergency induction of anaesthesia. The importance of best practice cannot be overstated because of high rates of mortality following acid aspiration.

METHODS

Literature searches were conducted using the key words cricoid pressure, Sellick manoeuvre, rapid sequence induction and acid aspiration syndrome. Articles were obtained from online searches, with literature published in the last 10 years being used; some seminal literature and textbooks were incorporated for definition purposes.

RESULTS

The literature displayed a disparity in practice and differing opinions on the optimal force to occlude the oesophagus. The role of education in correct application of cricoid pressure was explored, with unanimous conclusions that education plays a role in ensuring best practice.

CONCLUSIONS

Forces of 20-30 N are adequate to occlude the oesophagus and minimize the risk of acid aspiration. However, it is difficult for practitioners to accurately estimate this force in everyday practice. Various methods of assessing force were discussed, with the use of a 50-mL syringe suggested as a cost-effective and simple method to utilize in practice.

RELEVANCE TO CLINICAL PRACTICE

The literature review demonstrated that the subject of cricoid pressure is relevant in critical care practice in order to ensure patient safety during RSI. Thus, all critical care nurses have a duty to gain a working knowledge on the subject if patient safety is to be maintained. This paper provides a source of information on cricoid pressure and realistic methods of maintaining best practice.

Airway Management in Trauma: An Update

This article reviews the more recent theoretic and practical information that pertains to airway management in the trauma setting. This is followed by a presentation of the newer airway devices that may be advantageous in the management of the airway in trauma as well as a discussion of other devices, techniques, or maneuvers that are useful in the trauma setting but may be underused. Each clinician needs to be knowledgeable about the various airway options and then, based on one's own particular skills and resources, construct an airway management algorithm that works best for him or her. Each clinician needs to be knowledgeable about the various airway options, and then, based on the clinician's particular skills and resources, construct an airway management algorithm that works best.

Videolaryngoskopie zur modifizierten „Rapid-sequence-Narkoseeinleitung“

BACKGROUND

There is evidence that cricoid pressure, one of the key elements of rapid sequence induction (RSI) in patients at risk of aspiration, can distort the glottic view obtained by direct laryngoscopy (DL) and consequently impair or delay endotracheal intubation (ETI). The fact that cricoid pressure is applied by an assistant "blindly", i.e. without any visual feedback, is believed to be a contributing factor. Video laryngoscopy (VIL) offers the advantage that both the anaesthetist and the assistant can follow laryngoscopy. This could be useful for ETI during RSI.

METHODS

We used VIL for a simulated RSI in 170 adult patients randomised to either video laryngoscopy-guided application of cricoid pressure (group I) or conventional, i.e. "blind", application of cricoid pressure (group II). Time to ETI was compared between groups. The laryngoscopy view obtained by VIL was compared with the view of conventional DL obtained before, in all patients.

RESULTS

Time to ETI did not differ between groups (p=0.2): 25.1+/-14.2 s (group I) vs. 23.7+/-12.1 s (group II). Laryngoscopy scores were significantly better for VIL than conventional DL (p<0.001).

CONCLUSIONS

Visualisation of the larynx during RSI can be improved using VIL. Time to ETI is not decreased by use of video laryngoscopy-guided application of cricoid pressure.

Laryngeal view during laryngoscopy: a randomized trial comparing cricoid pressure, backward-upward-rightward pressure, and bimanual laryngoscopy

STUDY OBJECTIVE

External cricoid and thyroid cartilage manipulations are commonly taught to facilitate laryngeal view during intubation. We compare the laryngeal views during laryngoscopy with 4 manipulations (no manipulation, cricoid pressure, backward-upward-rightward pressure [BURP], and bimanual laryngoscopy) to determine the method that optimizes laryngeal view.

METHODS

This was a randomized intervention study involving emergency physicians participating in airway training courses from December 2003 to November 2004. Direct laryngoscopies were performed with curved blades on fresh, non-fixed cadavers by using each of the 4 methods. The percentage of glottic opening (POGO), a validated scoring scale, was recorded for each laryngoscopy. Scores for bimanual laryngoscopy were recorded before the assistant applied external pressure.

RESULTS

A total of 1,530 sets of comparative laryngoscopies were performed by 104 participants. One thousand one hundred eighteen of 1,530 sets (73%) had POGO scores less than 100 with no manipulation. Compared to no manipulation, mean POGO scores with bimanual laryngoscopy improved by 25 (95% confidence interval [CI] 23 to 27); mean POGO score improvement with cricoid pressure and BURP were 5 (95% CI 3 to 8) and 4 (95% CI 1 to 7), respectively. POGO scores with bimanual laryngoscopy were higher compared to cricoid pressure (mean difference 20, 95% CI 17 to 22) and BURP (mean difference 21, 95% CI 19 to 24). Among laryngoscopies with no manipulation in which the POGO score greater than 0 (n=1,434), laryngeal view worsened in 60 cases (4%, 95% CI 3% to 5%) with bimanual laryngoscopy, in 409 cases (29%, 95% CI 26% to 31%) with cricoid pressure, and in 504 cases (35%, 95% CI 33% to 38%) with BURP.

CONCLUSION

Using a cadaver model, we found pressing on the neck during curved blade laryngoscopy greatly affects laryngeal view. Overall, bimanual laryngoscopy improved the view compared to cricoid pressure, BURP, and no manipulation. Cricoid pressure and BURP frequently worsen laryngoscopy. These data suggest bimanual laryngoscopy should be considered when teaching emergency airway management.