The effect of neuromuscular blockade on the efficiency of facemask ventilation in patients difficult to facemask ventilate: a prospective trial

Executive Summary of the 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

The Airway section of the 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) present the Guidelines for the integral management of difficult airway in adult patients. This document provides recommendations based on current scientific evidence, theoretical-educational tools and implementation tools, mainly cognitive aids, applicable to the treatment of the airway in the field of anesthesiology, critical care, emergencies and prehospital medicine. Its principles are focused on the human factors, cognitive processes for decision-making in critical situations and optimization in the progression of the application of strategies to preserve adequate alveolar oxygenation in order to improve safety and quality of care.

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 II

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.

Prevalence and risk factors of difficult mask ventilation: A systematic review and meta-analysis

STUDY OBJECTIVE

This meta-analysis aimed at identifying the risk factors for and their strengths in predicting difficult mask ventilation (MV) through a systematic approach.

DESIGN

Meta-analysis of observational studies.

SETTING

Operating room.

INTERVENTION

Airway- or patient-related risk factors for difficult MV reported in over 20% of eligible studies identified through literature review.

PATIENTS

Adults receiving anesthetic induction with requirement of MV.

MEASUREMENTS

Databases including EMBASE, MEDLINE, Google Scholar, and Cochrane Library were searched from inception to July 2022. The primary outcomes were the identification of commonly reported risk factors for MV and a comparison of their strengths in difficult MV prediction, while the secondary outcomes were the prevalence of difficult MV in the general population and those with obesity.

MAIN RESULTS

Meta-analysis of 20 observational studies involving 335,846 patients identified 13 risk factors with predictive strengths (all p < 0.05): neck radiation (OR = 5.0, five studies, n = 277,843), increased neck circumference (OR = 4.04, 11 studies, n = 247,871), obstructive sleep apnea (OSA) (OR = 3.61, 12 studies, n = 331,255), presence of beard (OR = 3.35, 12 studies, n = 295,443), snoring (OR = 3.06, 14 studies, n = 296,105), obesity (OR = 2.99, 11 studies, n = 278,297), male gender (OR = 2.76, 16 studies, n = 320,512), Mallampati score III-IV (OR = 2.36, 17 studies, n = 335,016), limited mouth opening (OR = 2.18, six studies, n = 291,795), edentulous (OR = 2.12, 11 studies, n = 249,821), short thyroid-mental distance (OR = 2.12, six studies, n = 328,311), old age (OR = 2, 11 studies, n = 278,750), and limited neck movement (OR = 1.98, nine studies, n = 155,101). The prevalence of difficult MV was 6.1% (16 studies, n = 334,694) and 14.4% (four studies, n = 1152) in the general population and those with obesity, respectively.

CONCLUSIONS

Our results demonstrated the strengths of 13 most common risk factors for predicting difficult MV, which may serve as an evidence-based reference for clinicians to incorporate into their daily practice.

Comparison between pressure-controlled and manual ventilation during anesthetic induction in patients with expected difficult airway: A prospective randomized controlled trial

BACKGROUND

Gastric insufflation can cause gastric regurgitation, which may be exacerbated in patients who are expected to have difficult airways. The purpose of this study was to investigate the difference in respiratory parameters and the frequency of gastric insufflation according to the ventilation mode during the anesthestic induction on patients who were predicted to have difficult facemask ventilation.

METHODS

A total of eighty patients with expected airway difficulties were included. Patient were allocated to 2 groups (n = 40 each). In the manual ventilation group, ventilation was performed by putting a mask on the patient's face with 1-hand and adjusting the pressure limiting valve to 15 cm H2O. In the pressure-controlled ventilation group, a mask was held in place using 2-handed jaw-thrust maneuver. The pressure-controlled ventilation was applied and peak inspiration pressure was adjusted to achieve a tidal volume of 6 to 8 mL/kg. The primary outcome was the difference of the peak airway pressure between 2 groups every 30 seconds for 120 seconds duration of mask ventilation. We also evaluated respiratory variables including peak airway pressure, End-tidal carbon dioxide and also gastric insufflation using ultrasonography.

RESULTS

The pressure-controlled ventilation group demonstrated lower peak airway pressure than the manual ventilation group (P = .005). End-tidal carbon dioxide was higher in the pressure-controlled ventilation group (P = .012). The incidence of gastric insufflation assessed by real-time ultrasonography of the gastric antrum was higher in the manual ventilation group than in the pressure-controlled ventilation group [3 (7.5%) vs 17 (42.5%), risk ratio (95% confidence interval): 0.06 to 0.56, P = .003].

CONCLUSIONS

Pressure-controlled ventilation during facemask ventilation in patients who were expected to have difficult airways showed a lower gastric insufflation rate with low peak airway pressure compared to manual ventilation.

Ramped versus sniffing position in the videolaryngoscopy-guided tracheal intubation of morbidly obese patients: a prospective randomized study

BACKGROUND

Ramped positioning is recommended for intubating obese patients undergoing direct laryngoscopy. However, whether the use of the ramped position can provide any benefit in videolaryngoscopy-guided intubation remains unclear. This study assessed intubation time using videolaryngoscopy in morbidly obese patients in the ramped versus sniffing positions.

METHODS

This is a prospective randomized study in patients with morbid obesity (n = 82; body mass index [BMI] ≥ 35 kg/m2). Patients were randomly allocated to either the ramped or the standard sniffing position groups. During the induction of general anesthesia, difficulty in mask ventilation was assessed using the Warters scale. Tracheal intubation was performed using a C-MAC® D-Blade videolaryngoscope, and intubation difficulty was assessed using the intubation difficulty scale (IDS). The primary endpoint was the total intubation time calculated as the sum of the laryngoscopy and tube insertion times.

RESULTS

The percentage of difficult mask ventilation (Warters scale ≥ 4) was significantly lower in the ramped (n = 40) than in the sniffing group (n = 41) (2.5% vs. 34.1%, P < 0.001). The percentage of easy intubation (IDS = 0) was significantly higher in the ramped than in the sniffing group (70.0% vs. 7.3%, P < 0.001). The total intubation time was significantly shorter in the ramped than in the sniffing group (22.5 ± 6.2 vs. 40.9 ± 9.0, P < 0.001).

CONCLUSIONS

Compared with the sniffing position, the ramped position reduced intubation time in morbidly obese patients and effectively facilitated both mask ventilation and tracheal intubation using videolaryngoscopy.

What airway management information do anaesthetic charts prompt for? An audit of charts from 132 hospitals across Australia and New Zealand

Anaesthetists can make safer airway plans if they know which airway techniques worked previously and which ones did not. Anaesthetic charts do not always capture this information, however, and guidelines from the Australian and New Zealand College of Anaesthetists do not specify what details on airway management they should include. To assess how anaesthetic charts support airway documentation, we audited the airway management section of blank charts from 132 hospitals accredited for training by the Australian and New Zealand College of Anaesthetists. We evaluated charts for the presence of 17 clinically important data fields describing tracheal intubation, supraglottic airway use and bag-mask ventilation. Our audit revealed that data fields on anaesthetic charts focus more on tracheal intubation than bag-mask ventilation or supraglottic airway use. Nearly all charts (99%) had prompts for intubation and most had prompts for both operator technique and patient outcome. For supraglottic airway use, 95% of charts had at least one data field, but few had prompts for difficulty or outcome. For bag-mask ventilation, 58% of charts had a data field for difficulty but most of these were subjective; few (1.5%) included any outcome measures. Data fields describing bag-mask ventilation and supraglottic airway use were also inconsistent. In summary, data fields on Australian and New Zealand anaesthetic charts focus on tracheal intubation with consistent prompts for both operator method and outcome. The inclusion of fields for outcome and difficulty of bag-mask ventilation and supraglottic airway use could help clinicians make better records of airway management.

Emergencies in obstetric anaesthesia: a narrative review

We conducted a narrative review in six areas of obstetric emergencies: category-1 caesarean section; difficult and failed airway; massive obstetric haemorrhage; hypertensive crisis; emergencies related to neuraxial anaesthesia; and maternal cardiac arrest. These areas represent significant research published within the last five years, with emphasis on large multicentre randomised trials, national or international practice guidelines and recommendations from major professional societies. Key topics discussed: prevention and management of failed neuraxial technique; role of high-flow nasal oxygenation and choice of neuromuscular drug in obstetric patients; prevention of accidental awareness during general anaesthesia; management of the difficult and failed obstetric airway; current perspectives on the use of tranexamic acid, fibrinogen concentrate and cell salvage; guidance on neuraxial placement in a thrombocytopenic obstetric patient; management of neuraxial drug errors, local anaesthetic systemic toxicity and unusually prolonged neuraxial block regression; and extracorporeal membrane oxygenation use in maternal cardiac arrest.

Facemask ventilation and vocal cord angle following neuromuscular blockade: a prospective observational study. Anaesthesia 2022;77:1010-1017. [PMID: 35727620 DOI: 10.1111/anae.15786]

Numerous studies support the idea that neuromuscular blockade facilitates facemask ventilation after induction of anaesthesia. Although improved airway patency or pulmonary compliance and a resolution of laryngospasm have been suggested as possible causes, the exact mechanism remains unclear. We aimed to assess whether neuromuscular blockade improves facemask ventilation and to clarify whether this phenomenon is associated with the vocal cord angle. This prospective observational study included patients aged between 20 and 65 years scheduled for elective surgery under general anaesthesia. After induction of anaesthesia, patients' lungs were ventilated with pressure-controlled ventilation using a facemask. During facemask ventilation, a flexible bronchoscope was inserted through a self-sealing diaphragm at the elbow connector attached to the facemask and breathing circuit and positioned to allow a continuous view of the vocal cords. The mean tidal volume and vocal cord angle were measured before and after administration of neuromuscular blocking drugs. Of 108 patients, 100 completed the study. Mean (SD) tidal volume ((11.0 (3.9) ml.kg^-1 vs. 13.6 (2.6) ml.kg^-1 ; p < 0.001) and mean (SD) vocal cord angle (17° (10°) vs. 26° (5°); p < 0.001) increased significantly after neuromuscular blockade. The proportional increase in mean tidal volume after neuromuscular blockade was positively correlated with vocal cord angle (Spearman's ρ = 0.803; p < 0.001). In conclusion, neuromuscular blockade facilitated facemask ventilation, and the improvement was correlated with further opening of the vocal cords.

Rocuronium versus saline for effective facemask ventilation during anesthesia induction: a double-blinded randomized placebo-controlled trial

Background

Mask ventilation progressively improves after loss of consciousness during anesthesia induction possibly due to progression of muscle paralysis. This double-blinded randomized placebo-controlled study aimed to test a hypothesis that muscle paralysis improves mask ventilation during anesthesia induction.

Methods

Forty-four adults patients including moderate to severe obstructive sleep apnea undergoing scheduled surgeries under elective general anesthesia participated in this study. Randomly-determined test drug either rocuronium or saline was blinded to the patient and anesthesia provider. One-handed mask ventilation with an anesthesia ventilator providing a constant driving pressure and respiratory rate (15 breaths per minute) was performed during anesthesia induction, and changes of capnogram waveform and tidal volume were assessed for one minute. The needed breaths for achieving plateaued-capnogram (primary variable) within 15 consecutive breaths were compared between the test drugs.

Results

Measurements were successful in 38 participants. Twenty-one and seventeen patients were allocated into saline and rocuronium respectively. The number of breaths achieving plateaued capnogram did not differ between the saline (95% C.I.: 6.2 to 12.8 breaths) and rocuronium groups (95% C.I.: 5.6 to 12.7 breaths) (p = 0.779). Mean tidal volume changes from breath 1 was significantly greater in rocuronium group than saline group (95% C.I.: 0.56 to 0.99 versus 3.51 to 4.53 ml kg-IBW−1, p = 0.006). Significantly more patients in rocuronium group (94%) achieved tidal volume greater than 5 mg kg-ideal body weight−1 within one minute than those in saline group (62%) (p = 0.026). Presence of obstructive sleep apnea did not affect effectiveness of rocuronium for improvement of tidal volume during one-handed mask ventilation.

Conclusions

Use of rocuronium facilitates tidal volume improvement during one-handed mask ventilation even in patients with moderate to severe obstructive sleep apnea.

Trial registration

The clinical trial was registered at (05/12/2013, UMIN000012495): https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000014515

Prehospital Drug Assisted Airway Management: An NAEMSP Position Statement and Resource Document

Airway management is a critical intervention for patients with airway compromise, respiratory failure, and cardiac arrest. Many EMS agencies use drug-assisted airway management (DAAM) - the administration of sedatives alone or in combination with neuromuscular blockers - to facilitate advanced airway placement in patients with airway compromise or impending respiratory failure who also have altered mental status, agitation, or intact protective airway reflexes. While DAAM provides several benefits including improving laryngoscopy and making insertion of endotracheal tubes and supraglottic airways easier, DAAM also carries important risks. NAEMSP recommends:DAAM is an appropriate tool for EMS clinicians in systems with clear guidelines, sufficient training, and close EMS physician oversight. DAAM should not be used in settings without adequate resources.EMS physicians should develop clinical guidelines informed by evidence and oversee the training and credentialing for safe and effective DAAM.DAAM programs should include best practices of airway management including patient selection, assessmenct and positioning, preoxygenation strategies including apneic oxygenation, monitoring and management of physiologic abnormalities, selection of medications, post-intubation analgesia and sedation, equipment selection, airway confirmation and monitoring, and rescue airway techniques.Post-DAAM airway placement must be confirmed and continually monitored with waveform capnography.EMS clinicians must have the necessary equipment and training to manage patients with failed DAAM, including bag mask ventilation, supraglottic airway devices and surgical airway approaches.Continuous quality improvement for DAAM must include assessment of individual and aggregate performance metrics. Where available for review, continuous physiologic recordings (vital signs, pulse oximetry, and capnography), audio and video recordings, and assessment of patient outcomes should be part of DAAM continuous quality improvement.

A systematic review of meta-analyses comparing direct laryngoscopy with videolaryngoscopy

PURPOSE

In the preceding 20 years, many randomized-controlled trials and meta-analyses have compared direct Macintosh laryngoscopy with videolaryngoscopy. The videolaryngoscope blades have included both traditional Macintosh blades and hyperangulated blades. Macintosh and hyperangulated blades differ in their geometry and technique for tracheal intubation; certain patient populations may benefit from one blade type over another. The primary objective of this systematic review was to assess whether published meta-analyses comparing direct Macintosh laryngoscopy to videolaryngoscopy have accounted for the videolaryngoscope blade type. Secondary objectives evaluated heterogeneity among practitioner experience and specialty, clinical context, patient population, and original primary study outcomes.

SOURCE

A search was performed across Ovid Medline, Ovid Embase, ClinicalKey, PubMed, TRIP, AccessAnesthesiology, Google Scholar, and ANZCA discovery. A systematic review identified meta-analyses which compared direct Macintosh laryngoscopy to videolaryngoscopy. There were no patient age or clinical specialty restrictions. Exclusion criteria included non-English language, studies comparing non-Macintosh blade to videolaryngoscopy, and studies in awake patients.

PRINCIPAL FINDINGS

Twenty-one meta-analyses were identified that were published between 1 January 2000 and 7 May 2020. Macintosh and hyperangulated videolaryngoscope blades were combined in most studies (16/21; 76%). Heterogeneity was also present among practitioner experience (20/21; 95%), clinician specialty (15/21; 71%), and clinical locations (10/21; 48%). Adult and pediatric patients were combined or not defined in 5/21 studies (24%). The primary outcomes of the meta-analyses varied, with the most common (7/21; 33%) being first-pass tracheal intubation success.

CONCLUSIONS

Heterogeneity across important clinical variables is common in meta-analyses comparing direct Macintosh laryngoscopy to videolaryngoscopy. To better inform patient care, future videolaryngoscopy research should differentiate blade type, clinical context, and patient-related primary outcomes.

Canadian Airway Focus Group updated consensus-based recommendations for management of the difficult airway: part 1. Difficult airway management encountered in an unconscious patient

PURPOSE

Since the last Canadian Airway Focus Group (CAFG) guidelines were published in 2013, the literature on airway management has expanded substantially. The CAFG therefore re-convened to examine this literature and update practice recommendations. This first of two articles addresses difficulty encountered with airway management in an unconscious patient.

SOURCE

Canadian Airway Focus Group members, including anesthesia, emergency medicine, and critical care physicians, were assigned topics to search. Searches were run in the Medline, EMBASE, Cochrane Central Register of Controlled Trials, and CINAHL databases. Results were presented to the group and discussed during video conferences every two weeks from April 2018 to July 2020. These CAFG recommendations are based on the best available published evidence. Where high-quality evidence was lacking, statements are based on group consensus.

FINDINGS AND KEY RECOMMENDATIONS

Most studies comparing video laryngoscopy (VL) with direct laryngoscopy indicate a higher first attempt and overall success rate with VL, and lower complication rates. Thus, resources allowing, the CAFG now recommends use of VL with appropriately selected blade type to facilitate all tracheal intubations. If a first attempt at tracheal intubation or supraglottic airway (SGA) placement is unsuccessful, further attempts can be made as long as patient ventilation and oxygenation is maintained. Nevertheless, total attempts should be limited (to three or fewer) before declaring failure and pausing to consider "exit strategy" options. For failed intubation, exit strategy options in the still-oxygenated patient include awakening (if feasible), temporizing with an SGA, a single further attempt at tracheal intubation using a different technique, or front-of-neck airway access (FONA). Failure of tracheal intubation, face-mask ventilation, and SGA ventilation together with current or imminent hypoxemia defines a "cannot ventilate, cannot oxygenate" emergency. Neuromuscular blockade should be confirmed or established, and a single final attempt at face-mask ventilation, SGA placement, or tracheal intubation with hyper-angulated blade VL can be made, if it had not already been attempted. If ventilation remains impossible, emergency FONA should occur without delay using a scalpel-bougie-tube technique (in the adult patient). The CAFG recommends all institutions designate an individual as "airway lead" to help institute difficult airway protocols, ensure adequate training and equipment, and help with airway-related quality reviews.

Canadian Airway Focus Group updated consensus-based recommendations for management of the difficult airway: part 2. Planning and implementing safe management of the patient with an anticipated difficult airway

PURPOSE

Since the last Canadian Airway Focus Group (CAFG) guidelines were published in 2013, the published airway management literature has expanded substantially. The CAFG therefore re-convened to examine this literature and update practice recommendations. This second of two articles addresses airway evaluation, decision-making, and safe implementation of an airway management strategy when difficulty is anticipated.

SOURCE

Canadian Airway Focus Group members, including anesthesia, emergency medicine, and critical care physicians were assigned topics to search. Searches were run in the Medline, EMBASE, Cochrane Central Register of Controlled Trials, and CINAHL databases. Results were presented to the group and discussed during video conferences every two weeks from April 2018 to July 2020. These CAFG recommendations are based on the best available published evidence. Where high-quality evidence is lacking, statements are based on group consensus.

FINDINGS AND KEY RECOMMENDATIONS

Prior to airway management, a documented strategy should be formulated for every patient, based on airway evaluation. Bedside examination should seek predictors of difficulty with face-mask ventilation (FMV), tracheal intubation using video- or direct laryngoscopy (VL or DL), supraglottic airway use, as well as emergency front of neck airway access. Patient physiology and contextual issues should also be assessed. Predicted difficulty should prompt careful decision-making on how most safely to proceed with airway management. Awake tracheal intubation may provide an extra margin of safety when impossible VL or DL is predicted, when difficulty is predicted with more than one mode of airway management (e.g., tracheal intubation and FMV), or when predicted difficulty coincides with significant physiologic or contextual issues. If managing the patient after the induction of general anesthesia despite predicted difficulty, team briefing should include triggers for moving from one technique to the next, expert assistance should be sourced, and required equipment should be present. Unanticipated difficulty with airway management can always occur, so the airway manager should have a strategy for difficulty occurring in every patient, and the institution must make difficult airway equipment readily available. Tracheal extubation of the at-risk patient must also be carefully planned, including assessment of the patient's tolerance for withdrawal of airway support and whether re-intubation might be difficult.

How to optimize neuromuscular blockade in ambulatory setting?

PURPOSE OF REVIEW

The purpose of this review is to discuss the optimal use of neuromuscular blocking agents (NMBA) during ambulatory surgery, and to provide an update on the routine use of neuromuscular monitoring and the prevention of residual paralysis.

RECENT FINDINGS

The number of major surgical procedures performed in ambulatory patients is likely to increase in the coming years, following the development of laparoscopic and thoracoscopic procedures. To successfully complete these procedures, the proper use of NMBA is mandatory. The use of NMBA not only improves intubating conditions but also ventilation. Recent studies demonstrate that NMBA are much more the solution rather than the cause of airway problems. There is growing evidence that the paralysis of the diaphragm and the abdominal wall muscles, which are resistant to NMBA is of importance during laparoscopic surgery. Further studies are still required to determine when deep neuromuscular block [posttetanic count (PTC) < 5] is required perioperatively. There is now a consensus to use perioperatively neuromuscular monitoring and particularly objective neuromuscular monitoring in combination with reversal agents to avoid residual paralysis and its related morbidity (e.g. respiratory complications in the PACU).

SUMMARY

Recent data suggest that it is now possible to obtain a tight control of neuromuscular block to maintain optimal relaxation tailored to the surgical requirements and to obtain a rapid and reliable recovery at the end of the procedure.

The DIFFMASK score for predicting difficult facemask ventilation: a cohort study of 46,804 patients

Facemask ventilation is an essential part of airway management. Correctly predicting difficulties in facemask ventilation may reduce the risk of morbidity and mortality among patients at risk. We aimed to develop and evaluate a weighted risk score for predicting difficult facemask ventilation during anaesthesia. We analysed a cohort of 46,804 adult patients who were assessed pre-operatively airway for 13 predictors of difficult airway management and subsequently underwent facemask ventilation during general anaesthesia. We developed the Difficult Facemask (DIFFMASK) score in two consecutive steps: first, a multivariate regression analysis was performed; and second, the regression coefficients of the adjusted regression model were converted into a clinically applicable weighted point score. The predictive accuracy of the DIFFMASK score was evaluated by assessment of receiver operating characteristic curves. The prevalence of difficult facemask ventilation was 1.06% (95%CI 0.97-1.16). Following conversion of regression coefficients into 0, 1, 2 or 3 points, the cumulated DIFFMASK score ranged from 0 to 18 points and the area under the receiver operating characteristic curve was 0.82. The Youden index indicated a sum score ≥ 5 as an optimal cut-off value for prediction of difficult facemask ventilation giving a sensitivity of 85% and specificity of 59%. The DIFFMASK score indicated that a score of 6-10 points represents a population of patients who may require heightened attention when facemask ventilation is planned, compared with those patients who are obviously at a high- or low risk of difficulties. The DIFFMASK score may be useful in a clinical context but external, prospective validation is needed.

Preparation for and Management of “Failed” Laryngoscopy and/or Intubation

An airway manager’s primary objective is to provide a path to oxygenation. This can be achieved by means of a facemask, a supraglottic airway, or a tracheal tube. If one method fails, an alternative approach may avert hypoxia. We cannot always predict the difficulties with each of the methods, but these difficulties may be overcome by an alternative technique. Each unsuccessful attempt to maintain oxygenation is time lost and may incrementally increase the risk of hypoxia, trauma, and airway obstruction necessitating a surgical airway. We should strive to optimize each effort. Differentiation between failed laryngoscopy and failed intubation is important because the solutions differ. Failed facemask ventilation may be easily managed with an supraglottic airway or alternatively tracheal intubation. When alveolar ventilation cannot be achieved by facemask, supraglottic airway, or tracheal intubation, every anesthesiologist should be prepared to perform an emergency surgical airway to avert disaster.

An Anesthesiologist's Perspective on the History of Basic Airway Management: The "Modern" Era, 1960 to Present

This fourth and last installment of my history of basic airway management discusses the current (i.e., "modern") era of anesthesia and resuscitation, from 1960 to the present. These years were notable for the implementation of intermittent positive pressure ventilation inside and outside the operating room. Basic airway management in cardiopulmonary resuscitation (i.e., expired air ventilation) was de-emphasized, as the "A-B-C" (airway-breathing-circulation) protocol was replaced with the "C-A-B" (circulation-airway-breathing) intervention sequence. Basic airway management in the operating room (i.e., face-mask ventilation) lost its predominant position to advanced airway management, as balanced anesthesia replaced inhalation anesthesia. The one-hand, generic face-mask ventilation technique was inherited from the progressive era. In the new context of providing intermittent positive pressure ventilation, the generic technique generated an underpowered grip with a less effective seal and an unspecified airway maneuver. The significant advancement that had been made in understanding the pathophysiology of upper airway obstruction was thus poorly translated into practice. In contrast to consistent progress in advanced airway management, progress in basic airway techniques and devices stagnated.

Neuromuscular blockers and reversal agents and their impact on anesthesia practice

Neuromuscular blockers have long been an intricate part of the anesthesia regimen. The scientific progress in pharmacology and physiology has strengthened their clinical relevance, has helped to delineate with precision their medical role, and has enhanced the safety and effectiveness of their use. New frontiers in research will define further the role of these agents in modern anesthesia practice and guide their expanding and discrete clinical applications.