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

Fibreoptic intubation in airway management: a review article

Since the first use of the flexible fibreoptic bronchoscope, a plethora of new airway equipment has become available. It is essential for clinicians to understand the role and limitations of the available equipment to make appropriate choices. The recent 4th National Audit Project conducted in the United Kingdom found that poor judgement with inappropriate choice of equipment was a contributory factor in airway morbidity and mortality. Given the many modern airway adjuncts that are available, we aimed to define the role of flexible fibreoptic intubation in decision-making and management of anticipated and unanticipated difficult airways. We also reviewed the recent literature regarding the role of flexible fibreoptic intubation in specific patient groups who may present with difficult intubation, and concluded that the flexible fibrescope maintains its important role in difficult airway management.

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.

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.