Optimizing preoxygenation in adults

Comparison of preoxygenation with a high-flow nasal cannula and a simple face mask before intubation in Korean patients with head and neck cancer

BACKGROUND

Although preoxygenation is an essential procedure for safe endotracheal intubation, in some cases securing sufficient time for tracheal intubation may not be possible. Patients with head and neck cancer might have a difficult airway and need a longer time for endotracheal intubation. We hypothesized that the extended apneic period with preoxygenation via a high-flow nasal cannula (HFNC) is beneficial to patients who undergo head and neck surgery compared with preoxygenation with a simple mask.

METHODS

The study was conducted as a single-center, single-blinded, prospective, randomized controlled trial. Patients were divided into groups based on one of the two preoxygenation.

METHODS

HFNC group or simple facemask (mask group). Preoxygenation was performed for 5 minutes with each method, and endotracheal intubation for all patients was performed using a video laryngoscope. Oxygen partial pressures of the arterial blood were compared at the predefined time points.

RESULTS

For the primary outcome, the mean arterial oxygen partial pressure (PaO2 ) immediately after intubation was 454.2 mm Hg (95% confidence interval [CI], 416.9-491.5 mm Hg) in the HFNC group and 370.7 mm Hg (95% CI, 333.7-407.4 mm Hg) in the mask group (P=0.002). The peak PaO2 at 5 minutes after preoxygenation was not statistically different between the groups (P=0.355).

CONCLUSIONS

Preoxygenation with a HFNC extending to the apneic period before endotracheal intubation may be beneficial in patients with head and neck cancer.

Performances and limits of Bag-Valve-Device for pre-oxygenation and manual ventilation: A comparative bench and cadaver study

INTRODUCTION

Bag-Valve-Device (BVD) is the most frequently used device for pre-oxygenation and ventilation during cardiopulmonary resuscitation (CPR). A minimal expired fraction of oxygen (FeO2) above 0.85 is recommended during pre-oxygenation while insufflated volume (VTi) should be reduced during manual ventilation. The objective was to compare the performances of different BVD in simulated conditions.

METHODS

Nine BVD were evaluated during pre-oxygenation: spontaneous breathing patients were simulated on a test lung (mild and severe conditions). FeO2 was measured with and without positive end-expiratory pressure (PEEP). CO2 rebreathing was evaluated. Then, manual ventilation was performed by 36 caregivers (n = 36) from three hospitals on a specific manikin; same procedure was repeated by 3 caregivers (n = 3) on two human cadavers with three of the nine BVD: In non-CPR scenario and during mechanical CPR with Interrupted Chest Compressions strategy (30:2).

RESULTS

Pre-oxygenation: FeO2 was lower than 0.85 for three BVD in severe condition and for two BVD in mild condition. FeO2 was higher than 0.85 in eight of nine BVD with an additional PEEP valve (PEEP 5 cmH2O). One BVD induced CO2 rebreathing. Manual ventilation: For non-CPR manual ventilation, mean VTi was within the predefined lung protective range (4-8 mL/kg PBW) for all BVD on the bench. For CPR manual ventilation, mean VTi was above the range for three BVD on the bench. Similar results were observed on cadavers.

CONCLUSIONS

Several BVD did not reach the FeO2 required during pre-oxygenation. Manual ventilation was significantly less protective in three BVD. These observations are related to the different BVD working principles.

A comprehensive review of difficult airway management strategies for patient safety

Difficult airway management is critical to ensuring patient safety. It involves addressing the challenges and failures that can occur, even with skilled healthcare providers, during face mask ventilation, intubation, supraglottic airway placement, invasive airway procedures, or extubation. Although the incidence of the most critical situation in airway management, "cannot intubate, cannot oxygenate," is low at 0.0019-0.04%, its occurrence can have severe consequences, including dental injury, airway injury, hypoxic brain damage, and even death. This study aimed to offer healthcare providers a comprehensive and evidence-based approach for difficult airway management by reviewing recent guidelines and incorporating the latest evidence-based practices to improve their preparedness and competence in difficult airway management, and thus ultimately contribute to improved patient safety.

A quasi-experimental study of fresh oxygen flow on patients' oxygen reserve during mask-assisted ventilation under general anesthesia induction

Background

To compare the effect of different amounts of fresh oxygen flow on oxygen reserve in patients undergoing general anesthesia.

Methods

Seventy-two patients were enrolled in this quasi-experimental study. Patients were randomly divided into experimental groups with a fresh oxygen flow of 1 L/min, 2 L/min, 4 L/min, and 8 L/min (denoted as G1, G2, G3, and G4, respectively) for 2 min of mask-assisted ventilation. Safe apnea time (SAT) was the primary endpoint; SAT was defined as the time from the cessation of ventilation to the time the patient's pulse oxygen saturation (SpO2) decreased to 90%. Ventilation indicators such as end-tidal oxygen concentration (EtO2), end-tidal carbon dioxide partial pressure (EtCO2), SpO2, and carbon dioxide (CO2) elimination amount, during mask-assisted ventilation, were the secondary endpoints.

Results

The SAT of G1, G2, G3, and G4 were 305.1 ± 97.0 s, 315 ± 112.5 s, 381.3 ± 118.6 s, and 359 ± 104.4 s, respectively (p > 0.05). The EtO2 after 2 min of mask-assisted ventilation in groups G1, G2, G3, and G4 were 69.7 ± 8.8%, 75.2 ± 5.0%, 82.5 ± 3.3%, and 86.8 ± 1.5%, respectively (p < 0.05). Also, there was a moderate positive correlation between the fresh oxygen flow and EtO2 (correlation coefficient r = 0.52, 95% CI 0.31-0.67, p < 0.0001). The CO2 elimination in the G1 and G2 groups was greater than that in the G4 group (p < 0.05). There was no significant difference in other indicators among the groups (all p > 0.05).

Conclusion

The amount of fresh oxygen flow during mask-assisted ventilation was positively correlated with EtO2. Also, even though there was no significant difference, the patients' oxygen reserves increased with the increase in fresh oxygen flow.

High-flow oxygen therapy versus facemask preoxygenation in anticipated difficult airway management (PREOPTI-DAM): an open-label, single-centre, randomised controlled phase 3 trial

Background

Difficult airway management remains a critical procedure with life-threatening adverse events. Current guidelines suggest high-flow therapy by nasal cannulae (HFNC) as a preoxygenation device in this setting. However, there is an evidence gap to support this recommendation.

Methods

The PREOPTI-DAM study is an open-label, single-centre, randomised controlled phase 3 trial done at Nantes University Hospital, France. Patients were aged 18-90 years with one major or two minor criteria of anticipated difficult airway management, and requiring intubation for scheduled surgery, were eligible. Patients with body mass index >35 kg/m² were excluded. Patients were randomly allocated (1:1) to receive 4-min preoxygenation by HFNC or facemask. Randomisation was stratified according to the intubation strategy (laryngoscopic versus fiberoptic intubation). The primary outcome was the incidence of oxygen desaturation ≤94% or of bag-mask ventilation during intubation. The primary and safety analyses included the intention to treat population. This trial is registered with ClinicalTrials.gov (NCT03604120) and EudraCT (2018-A00434-51).

Findings

From September 4 2018 to March 31 2021, 186 patients were enrolled and randomly assigned. One participant withdrew consent and 185 (99.5%) were included in the primary analysis (HFNC, N = 95; Facemask, N = 90). The incidence of the primary outcome was not significantly different between the HFNC and the facemask groups, respectively 2 (2%) versus 7 (8%); adjusted difference, -5.6 [95% confidence interval (CI), -11.8 to 0.6], P = 0.10. In the HFNC group, 76 patients (80%) versus 53 (59%) in the facemask group, reported good or excellent intubation experiences; adjusted difference 20.5 [95% CI, 8.3-32.8], P = 0.016. Comparing HFNC with facemask, severe complication occurred in 22 (23%) versus 27 (30%) patients (P = 0.29), and moderate complication in 14 (15%) versus 18 (20%) patients (P = 0.35). No death or cardiac arrest occurred during the study.

Interpretation

Compared with facemask, HFNC did not significantly reduce the incidence of desaturation ≤94% or bag-mask ventilation during anticipated difficult intubation but the trial was underpowered to rule out a clinically significant benefit. Patient satisfaction was improved with HFNC.

Funding

Nantes University Hospital and Fisher & Paykel Healthcare.

Variability in oxygen delivery with bag-valve-mask devices: An observational laboratory simulation study

A bag-valve-mask (BVM) is a portable handheld medical device commonly used in airway management and manual ventilation. Outside of the operating theatre, BVM devices are often used to pre-oxygenate spontaneously breathing patients before intubation to reduce the risk of hypoxaemia. Pre-oxygenation is considered adequate when the end-tidal expiratory fraction of oxygen is greater than 0.85. There are reports that some BVM devices fail to deliver a satisfactory inspired oxygen (FiO₂) in spontaneously breathing patients due to variability in design. The primary aim of this study was to evaluate the efficacy of oxygen delivery of a broad range of adult and paediatric BVM devices at increasing tidal volumes using a mechanical lung to simulate spontaneous ventilation. The secondary aim was to evaluate the effect of BVM design on performance.Forty BVM devices were evaluated in a laboratory setting as part of a safety assessment requested by HealthShare New South Wales. The oxygen inlet of each BVM device was primed with 100% oxygen (15 l/min) for two min. The BVM device was then attached to the mechanical lung and commenced spontaneous breathing at a fixed respiratory rate of 12 breaths/min with an inspiratory: expiratory ratio of 1:2. For each device FiO₂ was measured after two min of spontaneous breathing. This process was repeated with small (250 ml), medium (500 ml) and large (750 ml) tidal volumes simulating adult breathing in adult BVM devices, and small (150 ml), medium (300 ml) and large (450 ml) tidal volumes simulating paediatric breathing in paediatric BVM devices. The test was repeated using up to five BVM devices of the same model (where supplied) at each tidal volume as a manufacturing quality control measure.Eight of the 40 devices tested failed to deliver a FiO₂ above 0.85 for at least one tidal volume, and five models failed to achieve this at any measured tidal volume. Concerningly, three of these devices delivered a FiO₂ below 0.55. Six of the eight poorly performing devices delivered reducing concentrations of inspired oxygen with increasing tidal volumes. Devices which performed the worst were those with a duckbill non-rebreather valve and without a dedicated expiratory valve.Several BVM devices available for clinical use in Australia did not deliver sufficient oxygen for reliable pre-oxygenation in a spontaneously breathing in vitro model. Devices with a duckbill non-rebreather valve and without a dedicated expiratory valve performed the worst. It is imperative that clinicians using BVM devices to deliver oxygen to spontaneously breathing patients are aware of the characteristics and limitations of the BVM devices, and that the standards for manufacture are updated to require safe performance in all clinical circumstances.

Ease and comfort of pre-oxygenation with high-flow nasal oxygen cannulae vs. facemask: a randomised controlled trial

The Difficult Airway Society recommends that all patients should be pre-oxygenated before the induction of general anaesthesia, but this may not always be easy or comfortable and anaesthesia may often be induced without full pre-oxygenation. We tested the hypothesis that high-flow nasal oxygen cannulae would be easier and more comfortable than facemasks for pre-oxygenation. We randomly allocated 199 patients undergoing elective surgery aged ≥ 10 years to pre-oxygenation using either high-flow nasal oxygen or facemask. Ease and comfort were assessed by anaesthetists and patients on 10-cm visual analogue scale and six-point smiley face scale, respectively. Secondary endpoints included end-tidal oxygen fraction after securing a definitive airway and time to secure an airway. A mean difference (95%CI) between groups in ratings of -0.76 (-1.25 to -0.27) cm for ease of use (p = 0.003) and -0.45 (-0.75 to -0.13) points for comfort (p = 0.006), both favoured high-flow nasal oxygen. A mean difference (95%CI) between groups in end-tidal oxygen fraction of 3.89% (2.41-5.37%) after securing a definitive airway also favoured high-flow nasal oxygen (p < 0.001). There was no significant difference between groups in the number of patients with hypoxaemia (S_p O₂  < 90%) or severe hypoxaemia (S_p O₂  < 85%) lasting ≥ 1 min or ≥ 2 min; in the proportion of patients with an end-tidal oxygen fraction < 87% in the first 5 min after tracheal intubation (52.2% vs. 58.9% in facemask and high-flow nasal oxygen groups, respectively; p = 0.31); or in time taken to secure an airway (11.6 vs. 12.2 min in facemask and high-flow nasal oxygen groups, respectively; p = 0.65). In conclusion, we found pre-oxygenation with high-flow nasal oxygen to be easier for anaesthetists and more comfortable for patients than pre-oxygenation with a facemask, with no clinically relevant differences in end-tidal oxygen fraction after securing a definitive airway or time to secure an airway. The differences in ease and comfort were modest.

Time to Renitrogenation After Maximal Denitrogenation in Healthy Volunteers in the Supine and Sitting Positions

Introduction: Prior to intubation, preoxygenation is performed to denitrogenate the lungs and create an oxygen reservoir. After oxygen is removed, it is unclear whether renitrogenation after preoxygenation occurs faster in the supine vs the sitting position. Methods: We enrolled 80 healthy volunteers who underwent two preoxygenation and loss of preoxygenation procedures (one while supine and one while sitting) via bag-valve-mask ventilation with spontaneous breathing. End-tidal oxygen (ETO2) measurements were recorded as fraction of expired oxygen prior to preoxygenation, at the time of adequate preoxygenation (ETO2 >85%), and then every five seconds after the oxygen was removed until the ETO2 values reached their recorded baseline. Results: The mean ETO2 at completion of preoxygenation was 86% (95% confidence interval 85-88%). Volunteers in both the supine and upright position lost >50% of their denitrogenation in less than 60 seconds. Within 25 seconds, all subjects had an ETO2 of <70%. Complete renitrogenation, defined as return to baseline ETO2, occurred in less than 160 seconds for all volunteers. Conclusion: Preoxygenation loss, or renitrogenation, occurred rapidly after oxygen removal and was not different in the supine and sitting positions. After maximal denitrogenation in healthy volunteers, renitrogenation occurred rapidly after oxygen removal and was not different in the supine and sitting positions.

Preoxygenation: from hardcore physiology to the operating room

If we define the human body by the mass of the elements that compose it, we could say that we are oxygen and other elements. Oxygen, in addition to being fundamental in our composition, is an element that we constantly need to support cellular respiration and, therefore, life. Interestingly, despite its importance, humans have not developed mechanisms that allow us to store it and, therefore, we are unable to sustain life if we are deprived of ventilation, even for brief periods. Accordingly, the ability to induce the cessation of ventilation in a patient must be accompanied by different technical and non-technical skills that allow the patient's safety to be maintained in this highly vulnerable state. Through the use of basic mathematical tools and comparative physiology, we hereby propose to review the physiological foundations of preoxygenation to understand the reasons behind the clinical recommendations in this field.

Spontaneous Breathing for Panendoscopy? Retrospective Cohort and Results of a French Practice Survey

Objective

Avoiding tracheal intubation by using general anesthesia with spontaneous breathing (GASB) is attractive for upper airway panendoscopy. The aim of this study was to estimate the incidence of adverse events during panendoscopy under GASB and to assess the practices of French anesthesiologists.

Study Design

Two-phase study: monocentric retrospective study and national survey.

Setting

University hospital center.

Methods

Patients who underwent a panendoscopy under GASB at the University Hospital of Angers between January 1 and December 31, 2014, were reviewed. Failure of GASB was defined as an episode of hypoxemia (SpO₂ ≤88%) or the need for face mask ventilation with or without tracheal intubation. Then, we sent an electronic survey to all members of the French Society of Anaesthesia and Intensive Care.

Results

Among the 95 included patients, 22 (23%) experienced a failure of GASB: 3 tolerated hypoxemia, 15 had face mask ventilation episodes, and 4 were intubated. Three factors were associated with failure: obesity (odds ratio, 11.94; 95% CI, 3.20-44.64), history of difficult intubation defined as a Cormack score ≥3 (odds ratio, 6.20; 95% CI, 1.51-25.41), and laryngeal tumor (odds ratio, 2.81; 95% CI, 1.04-7.56). Among the 3930 members of the French Society of Anaesthesia and Intensive Care in 2018, 662 (16.8%) responded to the survey. The 2 preferred techniques to perform panendoscopy were intubation (62%) and intravenous sedation with spontaneous breathing (37%).

Conclusion

Although general anesthesia with orotracheal intubation remains the preferred technique for panendoscopy in France, GASB is an attractive alternative with a low failure rate. Risk factors for failure are obesity, history of difficult intubation, and laryngeal tumor.

Anaesthesia protocol evaluation of the videolaryngoscopy with the McGrath MAC and direct laryngoscopy for tracheal intubation in 1000 patients undergoing rapid sequence induction: the randomised multicentre LARA trial study protocol

INTRODUCTION

Rapid sequence induction of anaesthesia is indicated in patients with an increased risk of pulmonary aspiration. The main objective of the technique is to reduce the critical time period between loss of airway protective reflexes and rapid inflation of the cuff of the endotracheal tube to minimise the chance of aspiration of gastric contents. The COVID-19 pandemic has reinforced the importance of first-pass intubation success to ensure patient and healthcare worker safety. The aim of this study is to compare the first-pass intubation success rate (FPS) using the videolaryngoscopy compared with conventional direct laryngoscopy in surgical patients with a high risk of pulmonary aspiration.

METHODS AND ANALYSIS

The LARA trial is a multicentre, patient-blinded, randomised controlled trial. Consecutive patients requiring tracheal intubation are randomly allocated to either the McGrath MAC videolaryngoscope or direct laryngoscopy using the Macintosh laryngoscope. The expected rate of FPS is 92% in the McGrath group and 82% in the Macintosh group. Each group must include a total of 500 patients to achieve 90% power for detecting a difference at the 5% significance level. Successful intubation with the FPS is the primary endpoint. The secondary endpoints are the time to intubation, the number of intubation attempts, the necessity of airway management alternatives, the visualisation of the glottis using the Cormack and Lehane Score and the Percentage Of Glottic Opening Score and definite adverse events.

ETHICS AND DISSEMINATION

The project is approved by the local ethics committee of the Medical Association of the Rhineland Palatine state (registration number: 2020-15502) and medical ethics committee of the University of Freiburg (registration number: 21-1303). The results of this study will be made available in form of manuscripts for publication and presentations at national and international meetings.

TRIAL REGISTRATION

NCT04794764.

Neuro-anesthesiology in pregnancy

Management of the pregnant patient requiring neurosurgery poses multiple challenges, juxtaposing pregnancy-specific considerations with that accompanying the safe provision of intracranial or spine surgery. There are no specific evidence-based recommendations, and case-by-case interdisciplinary discussions will guide informed decision-making about the timing of delivery vis-à-vis neurosurgery, the performance of cesarean delivery immediately before neurosurgery, consequences of neurosurgery on subsequent delivery, or even the optimal anesthetic modality for neurosurgery and/or cesarean delivery. In general, identifying whether increased intracranial pressure poses a risk for herniation is crucial before allowing neuraxial procedures. Modified rapid sequence induction with advanced airway approaches (videolaryngoscopic or fiberoptic) allows improved airway manipulation with reduced risks associated with endotracheal intubation of the obstetric airway. Currently, very few anesthetic drugs are avoided in the neurosurgical pregnant patient; however, ensuring access to critical care units for prolonged monitoring and assistance of the respiratory-compromised patient is necessary to ensure safe outcomes.

Hypoxic Hypoxia and Brain Function in Military Aviation: Basic Physiology and Applied Perspectives

Acute hypobaric hypoxia (HH) is a major physiological threat during high-altitude flight and operations. In military aviation, although hypoxia-related fatalities are rare, incidences are common and are likely underreported. Hypoxia is a reduction in oxygen availability, which can impair brain function and performance of operational and safety-critical tasks. HH occurs at high altitude, due to the reduction in atmospheric oxygen pressure. This physiological state is also partially simulated in normobaric environments for training and research, by reducing the fraction of inspired oxygen to achieve comparable tissue oxygen saturation [normobaric hypoxia (NH)]. Hypoxia can occur in susceptible individuals below 10,000 ft (3,048 m) in unpressurised aircrafts and at higher altitudes in pressurised environments when life support systems malfunction or due to improper equipment use. Between 10,000 ft and 15,000 ft (4,572 m), brain function is mildly impaired and hypoxic symptoms are common, although both are often difficult to accurately quantify, which may partly be due to the effects of hypocapnia. Above 15,000 ft, brain function exponentially deteriorates with increasing altitude until loss of consciousness. The period of effective and safe performance of operational tasks following exposure to hypoxia is termed the time-of-useful-consciousness (TUC). Recovery of brain function following hypoxia may also lag beyond arterial reoxygenation and could be exacerbated by repeated hypoxic exposures or hyperoxic recovery. This review provides an overview of the basic physiology and implications of hypoxia for military aviation and discusses the utility of hypoxia recognition training.

Effect of preoxygenation before isoflurane induction and rocuronium-induced apnea on time until hemoglobin desaturation in domestic chickens (Gallus gallus domesticus)

OBJECTIVE

To evaluate the time to hemoglobin oxygen desaturation in chickens (Gallus gallus domesticus) with and without preoxygenation before isoflurane induction of anesthesia and rocuronium-induced apnea.

STUDY DESIGN

Prospective, randomized crossover study.

ANIMALS

A total of 10 healthy adult Lohmann Brown-Lite hens.

METHODS

Hens were anesthetized with isoflurane for intravenous (IV) and intraarterial catheter placement and allowed to fully recover from anesthesia. Hens in the preoxygenation treatment were administered oxygen (2 L minute^-1) via a facemask for 3 minutes prior to induction of anesthesia with 3% isoflurane in oxygen. In the alternative treatment, hens were not preoxygenated prior to induction of anesthesia with isoflurane in oxygen. Apnea was then induced with rocuronium bromide (1.0 mg kg^-1) administered IV, and anesthesia was maintained with IV propofol infusion. A cloacal pulse oximeter measured hemoglobin oxygen saturation (SpO₂). Time was recorded from the start of apnea until SpO₂ was 90% (desaturation). The trachea was intubated, and anesthesia was maintained with isoflurane in oxygen with manual ventilation until spontaneous breathing returned and SpO₂ ≥ 99%. PaO₂ was measured before each treatment, after preoxygenation, postinduction and at desaturation. Data were analyzed between treatments using Wilcoxon matched-pairs signed rank tests with Holm-Šidák multiple comparison test, and within treatments using Friedman test with Dunn's multiple comparison test (p < 0.05). Data are reported as median (range).

RESULTS

Time from start of apnea until hemoglobin desaturation was not significantly different between preoxygenated and nonpreoxygenated hens [26.5 (16-50) seconds and 24.0 (5-57) seconds, respectively; p = 0.25]. No differences in PaO₂ between treatments were observed at any time point.

CONCLUSIONS AND CLINICAL RELEVANCE

Preoxygenation for 3 minutes before isoflurane mask induction of anesthesia and apnea does not significantly increase time until desaturation in hens.

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.

Time to adapt in the pandemic era: a prospective randomized non -inferiority study comparing time to intubate with and without the barrier box

Background

The challenges posed by the spread of COVID-19 disease through aerosols have compelled anesthesiologists to modify their airway management practices. Devices such as barrier boxes are being considered as potential adjuncts to full PPE’s to limit the aerosol spread. Usage of the barrier box raises concerns of delay in time to intubate (TTI). We designed our study to determine if using a barrier box with glidescope delays TTI within acceptable parameters to make relevant clinical conclusions.

Methods

Seventy-eight patients were enrolled in this prospective non-inferiority controlled trial and were randomly allocated to either group C (without the barrier box) or the study group BB (using barrier box). The primary measured endpoint is time to intubate (TTI), which is defined as time taken from loss of twitches confirmed with a peripheral nerve stimulator to confirmation of end-tidal CO _2. 15 s was used as non-inferiority margin for the purpose of the study. We used an unpaired two-sample single-sided t-test to test our non- inferiority hypothesis (H ₀: Mean TTI diff ≥15 s, H _A: Mean TTI diff < 15 s). Secondary endpoints include the number of attempts at intubation, lowest oxygen saturation during induction, and the need for bag-mask ventilation.

Results

Mean TTI in group C was 42 s (CI 19.2 to 64.8) vs. 52.1 s (CI 26.1 to 78) in group BB. The difference in mean TTI was 10.1 s (CI -∞ to 14.9). We rejected the null hypothesis and concluded with 95% confidence that the difference of the mean TTI between the groups is less than < 15 s (95% CI -∞ to 14.9,p = 0.0461). Our induction times were comparable (67.7 vs. 65.9 s).100% of our patients were intubated on the first attempt in both groups. None of our patients needed rescue breaths.

Conclusions

We conclude that in patients with normal airway exam, scheduled for elective surgeries, our barrier box did not cause any clinically significant delay in TTI when airway manipulation is performed by well-trained providers.

The study was retrospectively registered at clinicaltrials.gov (NCT04411056) on May 27, 2020.

Coping with airway emergencies: Get, Set, Go!

Airway emergencies are among the life-threatening events that are encountered in the operating room, emergency department or intensive care unit. They are important causes of preventable morbidity and mortality where time is the essence. It can be extremely challenging to rapidly assess the airway for early diagnosis and perform appropriate interventions simultaneously. Outcome depends on the implementation of an optimal strategy to establish a patent airway. Equally important is the overall stabilisation of the patient and management of the primary clinical condition as appropriate. Key components of management include early recognition of threatened airway, appropriate and timely airway intervention, and maintaining oxygenation. In this review, we describe aetiology, evaluation and management of airway emergencies.

Time to Loss of Preoxygenation in Emergency Department Patients

BACKGROUND

In patients requiring emergency rapid sequence intubation (RSI), 100% oxygen is often delivered for preoxygenation to replace alveolar nitrogen with oxygen. Sometimes, however, preoxygenation devices are prematurely removed from the patient prior to the onset of apnea, which can lead to rapid loss of preoxygenation.

OBJECTIVE

We sought to determine the elapsed time, on average, between removing the oxygen source and the loss of preoxygenation among non-critically ill patients in the emergency department (ED).

METHODS

We conducted a prospective, crossover study of non-critically ill patients in the ED. Each patient received two identical preoxygenation trials for 4 min using a non-rebreather mask with oxygen flow at flush rate and a nasal cannula with oxygen flow at 10 L/min. After each preoxygenation trial, patients underwent two trials in random order while continuing spontaneous breathing: 1) removal of both oxygen sources and 2) removal of non-rebreather mask with nasal cannula left in place. We defined loss of preoxygenation as an end-tidal oxygen (exhaled oxygen percentage; EtO₂) value < 70%. We measured EtO₂ breath by breath until loss of preoxygenation occurred.

RESULTS

We enrolled 42 patients, median age was 43 years (interquartile range [IQR] 30 to 54 years) and 72% were male. Median time to loss of preoxygenation was 20 s (IQR 17-25 s, 4.5 breaths) when all oxygen devices were removed, and 39 s (IQR 21-56 s, 8 breaths) when the nasal cannula was left in place.

CONCLUSIONS

In this population of non-critically ill ED patients, most had loss of preoxygenation after 5 breaths if all oxygen devices were removed, and after 8 breaths if a nasal cannula was left in place. These data suggest that during ED RSI, preoxygenation devices should be left in place until the patient is completely apneic.

Current practice of rapid sequence induction in adults: A national survey among anesthesiologists in Spain

BACKGROUND

Rapid sequence induction (RSI) in adults has undergone changes in recent years due to pharmacological and technological advances. The objective of this survey was to evaluate current practice among Spanish anesthesiologists.

METHODS

A 31-item questionnaire regarding RSI practice was sent to anesthesiologists working in Spanish public hospitals. Differences in responses according to the type of hospital or experience of the respondent were compared for all data using the chi-square and Fisher's exact test.

RESULTS

Approximately 15.89% of Spanish anesthesiologists participated in the survey (1002 questionnaires). The results show considerable heterogeneity in most aspects of RSI. Less than 20% of respondents administer sodium citrate. Sixty-four percent place a nasogastric tube in patients with intestinal obstruction. Gastric residue is assessed by ultrasound in 6% of cases. Only 25% of respondents measure ETO₂ to check the effectiveness of preoxygenation, and 22% use nasal oxygen insufflation with nasal prongs or THRIVE. Sixty two percent of respondents apply cricoid pressure, but only 50% release the pressure when encountering intubation difficulty. Up to 40% of respondents reported cases of aspiration despite applying cricoid pressure. Propofol was the most commonly used hypnotic (97.6%), but there was no clear preference in the choice of neuromuscular relaxant (suxamethonium versus rocuronium ratio of approximately 1:1). Only 44% of respondents calculated the dose of sugammadex that would be required for emergency reversal of rocuronium.

CONCLUSIONS

The survey showed significant variation in RSI practice, similar to that of other countries. Quality prospective studies are needed to standardize clinical practice.

High-Risk Airway Management in the Emergency Department. Part I: Diseases and Approaches

BACKGROUND

Successful airway management is critical to the practice of emergency medicine. Emergency physicians must be ready to optimize and prepare for airway management in critically ill patients with a wide range of physiologic challenges. Challenges in airway management commonly encountered in the emergency department are discussed using a pearl and pitfall discussion in this first part of a 2-part series.

OBJECTIVE

This narrative review presents an evidence-based approach to airway and patient management during endotracheal intubation in challenging cases that are commonly encountered in the emergency department.

DISCUSSION

Adverse events during emergent airway management are common, with postintubation cardiac arrest reported in as many as 1 in 25 intubations. Many of these adverse events can be avoided with the proper identification and understanding of the underlying physiology, preparation, and postintubation management. Patients with high-risk features including severe metabolic acidosis; shock and hypotension; obstructive lung disease; pulmonary hypertension, right ventricle failure, and pulmonary embolism; and severe hypoxemia must be managed with airway expertise.

CONCLUSIONS

This narrative review discusses the pearls and pitfalls of commonly encountered physiologic high-risk intubations with a focus on the emergency clinician.

High-Risk Airway Management in the Emergency Department: Diseases and Approaches, Part II

BACKGROUND

Successful airway management is critical to the practice of emergency medicine. Thus, emergency physicians must be ready to optimize and prepare for airway management in critically ill patients with a wide range of physiologic challenges. Challenges in airway management commonly encountered in the emergency department are discussed using a pearl and pitfall discussion in this second part of a 2-part series.

OBJECTIVE

This narrative review presents an evidence-based approach to airway and patient management during endotracheal intubation in challenging cases commonly encountered in the emergency department.

DISCUSSION

Adverse events during emergent airway management are common with postintubation cardiac arrest, reported in as many as 1 in 25 intubations. Many of these adverse events can be avoided by proper identification and understanding the underlying physiology, preparation, and postintubation management. Those with high-risk features including trauma, elevated intracranial pressure, upper gastrointestinal bleed, cardiac tamponade, aortic stenosis, morbid obesity, and pregnancy must be managed with airway expertise.

CONCLUSIONS

This narrative review discusses the pearls and pitfalls of commonly encountered physiologic high-risk intubations with a focus on the emergency clinician.

Transnasal humidified rapid insufflation ventilatory exchange vs. facemask oxygenation in elderly patients undergoing general anaesthesia: a randomized controlled trial

Transnasal humidified rapid insufflation ventilator exchange (THRIVE) may be effective in delaying hypoxia, but the efficacy of THRIVE for oxygenation in elderly patients under general anaesthesia has not been assessed. This study assessed whether THRIVE prolonged the apnoea time in the elderly patients after induction. This was a single centre, two-group, randomized controlled trial. 60 patients (65 to 80 years of age) with American Society of Anesthesiologists (ASA) grades I ~ III who required tracheal intubation or the application of a laryngeal mask under general anaesthesia were randomly allocated to receive oxygenation using THRIVE (100% oxygen, 30~70 litres min⁻¹) or a facemask (100% oxygen, 10 litres min⁻¹) during the pre-oxygenation period and during apnoea. The apnoea time, which was defined as the time from the cessation of spontaneous breathing until the SpO₂ decreased to 90% or the apnoea time reached 10 minutes was recorded as the primary outcome. No significant differences were found on the baseline characteristics between the groups. The apnoea time was significantly increased (P < 0.01) in the THRIVE group. The median (interquartile range) apnoea times were 600 (600–600) s in the THRIVE group and 600 (231.5–600) s in the facemask group. No significant differences were found in the PaO₂, PaCO₂ and vital parameters between the THRIVE and facemask groups. No increased occurrence of complications, including haemodynamic instability, resistant arrhythmia or nasal discomfort, were reported in both the THRIVE group and the facemask group. THRIVE prolongs the apnoea time in elderly patients. THRIVE may be a more effective method for pre-oxygenation than a facemask in the elderly without pulmonary dysfunction.

Evaluation of time to intubation and rate of success for different healthcare professionals using a double-lumen left-sided endotracheal video tube: A prospective observational study

Intubation with a double-lumen left-sided endotracheal video tube has been the standard procedure for nearly five years in the Department of Cardiothoracic Surgery, Copenhagen University Hospital, but no systematic evaluations have been done. For a 12-month period ending November 2017, data were collected from 579 consecutive patients, scheduled for thoracic surgery with a requirement for one-lung ventilation; 35 anaesthetist trainees (nurses or doctors) (287 cases), 27 nurse anaesthetists (239 cases) and 8 anaesthesiologists (53 cases) managed intubation with a double-lumen tube. Time to intubation was relatively equal across healthcare professionals with a mean time of 53 (anaesthetist trainees), 40 (nurse anaesthetists) and 63 (anaesthesiologists) seconds. The shorter time for nurse anaesthetists and prolonged time for anaesthesiologists might be due to the small number of cases and the fact that anaesthesiologists carried out 60% of the cases, where a third attempt was needed, and 25% of cases for the anaesthesiologists were assessed to a Cormack-Lehane grade of 3 or 4 compared to 6% for anaesthetist trainees and 5% for nurse anaesthetists. The rate of successful placement in the first attempt of placing the double-lumen left-sided endotracheal video tube was high, which emphasises that intubation with a double-lumen left-sided endotracheal video tube is suitable for use by different healthcare professionals.

Acute and Chronic Respiratory Failure in Cancer Patients

In 2016, there was an estimated 1.8 million new cases of cancer diagnosed in the United States. Remarkable advances have been made in cancer therapy and the 5-year survival has increased for most patients affected by malignancy. There are growing numbers of patients admitted to intensive care units (ICU) and up to 20% of all patients admitted to an ICU carry a diagnosis of malignancy. Respiratory failure remains the most common reason for ICU admission and remains the leading causes of death in oncology patients. There are many causes of respiratory failure in this population. Pneumonia is the most common cause of respiratory failure, yet there are many causes of respiratory insufficiency unique to the cancer patient. These causes are often a result of immunosuppression, chemotherapy, radiation treatment, or hematopoietic stem cell transplant (HCT). Treatment is focused on supportive care and specific therapy for the underlying cause of respiratory failure. Noninvasive modalities of respiratory support are available; however, careful patient selection is paramount as indiscriminate use of noninvasive positive pressure ventilation is associated with a higher mortality if mechanical ventilation is later required. Historically, respiratory failure in the cancer patient had a grim prognosis. Outcomes have improved over the past 20 years. Survivors are often left with significant disability.

High-flow nasal oxygenation for anesthetic management

High-flow nasal oxygenation (HFNO) is a promising new technique for anesthesiologists. The use of HFNO during the induction of anesthesia and during upper airway surgeries has been initiated, and its applications have been rapidly growing ever since. The advantages of this technique include its easy set-up, high tolerability, and its abilities to produce positive airway pressure and a high fraction of inspired oxygen and to influence the clearance of carbon dioxide to some extent. HFNO, via a nasal cannula, can provide oxygen both to patients who can breathe spontaneously and to those who are apneic; further, this technique does not interfere with bag-mask ventilation, attempts at laryngoscopy for tracheal intubation, and surgical procedures conducted in the airway. In this review, we describe the techniques associated with HFNO and the advantages and disadvantages of HFNO based on the current state of knowledge.

Addition of Nasal Cannula Can Either Impair or Enhance Preoxygenation With a Bag Valve Mask: A Randomized Crossover Design Study Comparing Oxygen Flow Rates

BACKGROUND

A critical safety component of emergency anesthesia is the avoidance of hypoxemia during the apneic phase of a rapid sequence intubation. Preoxygenation with a bag valve mask (BVM) or anesthetic circuit may be improved with supplemental oxygen by nasal cannula (NC) if there is a mask leak. In addition, NC is recommended for apneic oxygenation after induction and may be placed before preoxygenation. However, the optimum NC flow rate for preoxygenation or whether the presence of NC alone creates a mask leak remains unclear.

METHODS

We performed a randomized crossover study on healthy volunteers comparing BVM alone and BVM with NC flow rates of 0 (NC-0), 5 (NC-5), 10 (NC-10), and 15 (NC-15) liters per minute (lpm). Our primary outcome was end-tidal oxygen (ETO2) after 3-minute preoxygenation.

RESULTS

There was no difference in ETO2 between NC-15, NC-10, or BVM-only at 3 minutes. NC-0 and NC-5 recorded significantly lower ETO2 at all times compared with NC-15, NC-10, or BVM-only (least difference NC-5, -7% [95% confidence interval {CI}, -4% to -10%), NC-0, 16% [95% CI, 13%-19%]). There was a difference in ETO2 between NC-15 and BVM-only at 1 minute (7%; 95% CI, 5%-9%), but not at 2 or 3 minutes. There was no difference in ETO2 between NC-10 and NC-15.

CONCLUSIONS

Our study found that NC at 0 and 5 lpm with a BVM is deleterious to preoxygenation and should be avoided. In addition, a lack of difference between NC-10 and BVM-only demonstrates that NC at flows of at least 10 lpm should not impair the preoxygenation process. While NC-15 may offer a benefit by reaching maximal ETO2 at 1 minute, this would need to be balanced against patient comfort.

Comparison of preoxygenation efficiency with Intersurgical Economy and Intersurgical QuadraLite anaesthetic face masks

BACKGROUND

Sufficient preoxygenation prevents arterial oxygen desaturation prior to intubation. An optimally sealed facemask is necessary for fast preoxygenation. The study was aimed at comparing the efficiency of preoxygenation using two different face masks.

MATERIALS AND METHODS

In 2018, a prospective study was conducted. Patients were classified into two groups: group A - Intersurgical Economy face masks, group B - Intersurgical QuadraLite masks. The circuit was flushed with 100% O2 for 30s, preoxygenation started with flow of 8l/min, FiO2100. The patients were asked to breathe deeply. Fentanyl (1-2 mcg/kg) was administered to increase mask toleration. End-tidal oxygen concentration (EtO2) ≥90% was the goal. EtO2 was monitored after 30, 60, 90, 120, 180, 210, 240, 270 and 300 seconds. Data was analyzed using the Independent-Samples T-test and the Mann-Whitney-U test.

RESULTS

Twelve patients were enrolled in group A and 19 in group B. Differences in sex, age, BMI and Mallampati class in the groups were statistically insignificant (p = 0.13, 0.39, 0.65, 0.43 respectively). Patients assigned to ASA I - 25.8% (n = 8->2/6), ASA II - 71.0 % (n = 22->10/12), ASA III - 3.2% (n = 1->0/1), p = 0.64. The success rate of preoxygenation to EtO290 within 5 min was statistically significantly different in the groups, with 33.3% in group A and 94.7% in group B (p < 0.01). Mean time to EtO290 was 228.3 ± 104.0/164.4 ± 84.3. Mean EtO2 after: 30s - 56.0 ± 13.5/69.3 ± 11.2 (p < 0.01); 60s - 63.8 ± 15.3/76.1 ± 11.7 (p = 0.02), 90s - 67.8 ± 17.7/80.7 ± 10.1 (p = 0.03); 120s-69.6 ± 18.2/83.4 ± 10.0 (p = 0.03), 150s-71.1 ± 19.0/87.1 ± 6.5 (p = 0.01); 180s - 72.9 ± 16.8/88.5 ± 5.3 (p = 0.01), 210s - 72.6 ± 18.0/89.2 ± 5.1 (p < 0.01); 240s - 74.17 ± 15.4/90.0 ± 4.3 (p < 0.01), 270s-76.3 ± 16.3/90.2 ± 3.6; 300s - 77.8 ± 14.6/90.2 ± 1.5 (p < 0.01).

CONCLUSIONS

Preoxygenation was significantly more efficient and faster with Intersurgical QuadraLite face masks.

Does apneic oxygenation prevent desaturation during emergency airway management? A systematic review and meta-analysis

RéSUMé: OBJECTIF: L'oxygénation apnéique (OA) par lunettes nasales est une méthode de prévention de la désaturation en oxygène au cours des intubations en urgence. L'objectif de cette revue systématique était de déterminer l'efficacité de l'OA sur la prévention de la désaturation en oxygène au cours des intubations en urgence.

SOURCE

Des recherches systématiques ont été effectuées dans trois bases de données électroniques (MEDLINE, EMBASE et CINAHL) pour identifier les études portant sur la prévention de la désaturation en oxygène au moyen de l'OA par lunettes nasales. Notre critère d'évaluation principal était l'incidence des désaturations telle que définie dans chaque étude; nous avons ensuite évalué l'incidence de la désaturation sévère en oxygène (SpO₂ < 80%). Une méta-analyse a été effectuée sur les études présentant des données sur la désaturation en oxygène telle que définie par chaque étude et chez des patients ayant une désaturation sévère pour générer une estimation groupée de l'effet.

CONSTATATIONS PRINCIPALES

Au total, 544 études ont été examinées, parmi lesquelles dix (2 322 patients) satisfaisaient tous les critères d'éligibilité. Comparativement à l'absence d'OA, l'utilisation de cette méthode a été associée à une réduction de la désaturation en oxygène (risque relatif [RR] : 0,76; intervalle de confiance à 95% [IC] : 0,61 à 0,95; P = 0,02), mais n'a pas été associée à une réduction de la désaturation sévère (RR, 0,65; IC à 95% : 0,38 à 1,11; P = 0,12). Néanmoins, il y avait une hétérogénéité significative des facteurs liés aux patients, des interventions et des définitions de la désaturation en oxygène entre les études.

CONCLUSION

Nos constatations suggèrent que l'OA par lunettes nasales est associée à un moindre risque de désaturation en oxygène au cours des intubations en urgence. Cependant, compte de tenu de l'hétérogénéité des études, d'autres essais de grande qualité sont nécessaires pour déterminer quels patients pourraient bénéficier de l'OA au cours des intubations d'urgence.

Apnoeic oxygenation by nasal cannula during airway management in children undergoing general anaesthesia: a pilot randomised controlled trial

Background

Airway management is a core clinical skill in anaesthesia. Pre-oxygenation prior to induction of anaesthesia is a standard practice to prevent desaturation. Apnoeic oxygenation in adults is effective and prolongs the time to desaturation. The effectiveness of apnoeic oxygenation in the adult is well documented; however, evidence in the paediatric is lacking. Therefore, the aim of this study was to investigate the effectiveness of apnoeic oxygenation during airway management in children.

Methods

This was a pilot randomised controlled trial. Patients were randomised to receive either apnoeic oxygenation or standard care during the induction of anaesthesia. The primary outcome was the duration of safe apnoea, defined as a composite of the time to first event, either time for SpO2 to drop to 92% or time to successfully secure the airway, and the lowest SpO2 observed during airway management. Secondary outcomes were the number of patients whose SpO2 dropped below 95% and the number of patients whose SpO2 dropped below 92%.

Results

A total of 30 patients were randomised, 15 to apnoeic oxygenation and 15 to standard care. No significant difference was observed in the time to first event (p = 0.870). However, patients randomised to apnoeic oxygenation had significantly higher SpO2 observed compared to the standard care group (p = 0.004). All patients in the apnoeic oxygenation group maintained SpO2 of 100% during airway management, compared to only six in the standard care group. SpO2 dropped below 92% in one patient, with the lowest SPO₂ recorded 73%.

Conclusion

This study suggests that providing 3 l/min oxygen by nasal cannula following pre-oxygenation contributes to maintaining high levels of oxygen saturation during airway management in children, contributing to increased patients’ safety during general anaesthesia.

Trial registration

Retrospectively registered at ClinicalTrials.gov, NCT03271827. Registered: 4 September 2017.

Efficiency and Efficacy of Two Techniques of Preoxygenation during Modified Rapid Sequence Intubation

Background:

Apneic mass movement of oxygen by applying continuous positive airway pressure (CPAP) is possible only when the airway is kept patent which helps to reduce the rate of desaturation.

Aims:

The aim of this study was to check the efficiency of preoxygenation and apneic oxygenation by assessing the drop in partial pressure of arterial oxygen (PaO₂) during apnea with and without keeping an oropharyngeal airway to maintain the patency of airway.

Settings and Design:

This prospective observational study was conducted at a tertiary care center.

Materials and Methods:

Sixty patients undergoing robotic and laparoscopic-assisted surgeries requiring modified rapid sequence intubation were recruited for the study. In Group A, CPAP was not applied during preoxygenation and oropharyngeal airway was not used, but oxygen was administered at 5 L/min during the apnea. In Group B, CPAP of 5 cmH₂O was maintained during preoxygenation and after induction an oropharyngeal airway was inserted. Patients in both the groups were induced and paralyzed following standardized anesthesia protocol.

Statistical Analysis Used:

Chi-square test, independent t-test, and ANCOVA were used as applicable.

Results:

Group B showed significantly higher mean PaO₂ levels after preoxygenation (525.3 ± 42.5 vs. 500.8 ± 51) and at 90 s of apnea (494.8 ± 42.6 vs. 368.6 ± 98.4) as compared to Group A. The fall in PaO₂ was significantly lower in Group B. The rise in partial pressure of arterial carbon dioxide was comparable in both groups.

Conclusion:

Preoxygenation with CPAP of 5 cmH₂O followed by apneic oxygenation with CPAP keeping the airway patent with an oropharyngeal airway results in significantly higher PaO₂ after preoxygenation and slower reduction in PaO₂ during apnea.

Effects of Preoxygenation with Tidal Volume Breathing Followed by Apneic Oxygenation with and without Continuous Positive Airway Pressure on Duration of Safe Apnea Time and Arterial Blood Gases

Background:

Application of continuous positive airway pressure (CPAP) helps to recruit collapsed areas of the lung, which improves the oxygen reserve.

Aim of the Study:

To compare the time to desaturate to 90% during apnea following preoxygenation and apneic ventilation with tidal volume breathing for 3 min with and without the application of CPAP.

Settings and Design:

This prospective randomized study was conducted in a tertiary care institution.

Subjects and Methods:

Twenty adult surgical patients were allocated into two groups. Group C patients were preoxygenated with 100% oxygen with CPAP of 20 cm H₂O for 3 min. Group P patients were preoxygenated for 3 min without CPAP. In Group C, apneic oxygenation was initiated following induction and neuromuscular blockade with CPAP of 20 cm H₂O. In Group P, no CPAP was applied. The study was terminated when the patient desaturated to 90%.

Statistical Analysis Used:

Chi-square test and Mann–Whitney test.

Results:

Group C had a significantly longer apnea time as compared to Group P (816.00 ± 30.98 vs. 348.00 ± 122.64 s). Three patients in Group P desaturated to <90% by 3 min and the remaining soon after 6 min. No patient in Group C desaturated till 12 min of apnea. PaO₂ was significantly higher in Group C at 3 and 6 min of apnea. At 3 and 6 min, Group P had significantly lower saturation as compared to Group C.

Conclusion:

Preoxygenation with CPAP significantly delayed desaturation during apnea with significantly higher arterial partial pressure of oxygen as compared to preoxygenation without CPAP.

Comparison of Arterial Oxygenation and Acid-Base Balance with the use of Transnasal Humidified Rapid-insufflation Ventilatory Exchange versus Tidal Volume Breathing with Continuous Positive Airway Pressure for Preoxygenation and Apneic Ventilation

Background:

Preoxygenation and apneic ventilation prolong apnea time without desaturation.

Aims:

The primary objective of this study is to compare arterial oxygenation during the periods of apnea following preoxygenation and apneic ventilation with tidal volume breathing for 3 min with continuous positive airway pressure (CPAP) versus with transnasal humidified rapid-insufflation ventilatory exchange (THRIVE).

Settings and Designs:

This prospective randomized study was conducted in 20 adult patients at a tertiary care institution.

Subjects and Methods:

Group C patients (n = 10) were preoxygenated with 100% oxygen using a face mask at a rate of 6 L/min for 3 min with CPAP of 15 cm of H₂O. In Group H, oxygen was administered using THRIVE at 30 L/min for 3 min. Apneic ventilation was given in Group C with 10 L/min oxygen with CPAP of 15 cm H₂O and in Group H with THRIVE at 60 L/min. The endpoint was desaturation to 90% or maximum duration of 12 min.

Statistical Analysis Used:

Chi-square test and Mann–Whitney test.

Results:

Both groups tolerated apnea for 12 min without desaturation. PaO₂ in Group C was significantly higher than Group H from 3 min of apnea to 12 min. The PaCO₂ was significantly lower in Group C from 6 min. The pH was comparable in both groups except at 12 min with Group H having significantly lower pH.

Conclusion:

Tidal volume breathing with CPAP resulted in significantly higher arterial oxygen levels than THRIVE, though both modalities were equally effective in prolonging apnea time without desaturation up to 12 min. Group C showed an added advantage of lower PaCO₂ with less acidemia.

Effectiveness of transnasal humidified rapid-insufflation ventilatory exchange versus traditional preoxygenation followed by apnoeic oxygenation in delaying desaturation during apnoea: A preliminary study

Background and Aims:

Transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) during apnoea has shown to delay desaturation. The primary objective was to compare time to desaturate to <90% during apnoea with THRIVE versus traditional preoxygenation followed by apnoeic oxygenation.

Methods:

This prospective, randomised, single-blinded study was conducted in 10 adult patients presenting for direct laryngoscopy under general anaesthesia without endotracheal intubation. Group P patients were preoxygenated with 100% oxygen, and in Group H, high-flow humidified oxygen was delivered using nasal cannula for 3 min. After induction and neuromuscular blockade, time to desaturate to 90%, while receiving apnoeic oxygenation, was noted. Chi-square test and Mann–Whitney tests were used.

Results:

Group H had a significantly longer apnoea time as compared to Group P (796.00 ± 43.36 vs. 444.00 ± 52.56 s). All patients in Group H continued to have nearly 100% saturation even at 12 min of apnoea. However, in Group P, 80% of patients desaturated to <90% after 6 min of apnoea. Baseline blood gases, that following preoxygenation and at 3 min of apnoea time were comparable in both groups. At 6 min, Group H had a significantly higher PaO₂ (295.20 ± 122.26 vs. 135.00 ± 116.78) and PaCO₂ (69.46 ± 7.15 vs. 59.00 ± 4.64). Group H continued to have a PaO₂ of >200 mmHg even at 12 min of apnoea with a significant rise in PaCO₂ along with fall in pH after 6 min.

Conclusion:

During apnoeic periods time to desaturate to <90% was significantly prolonged with use of THRIVE.

Perioperative Care of the Obese Cardiac Surgical Patient

Morbid obesity is associated with impairment of cardiovascular, pulmonary, gastrointestinal, and renal physiology with significant perioperative consequences and has been linked with higher morbidity and mortality after cardiac surgery. Cardiac surgery patients have a higher incidence of difficult airway and difficult laryngoscopy than general surgery patients do, and obesity is associated with difficult mask ventilation and direct laryngoscopy. Positioning injuries occur more frequently because obese patients are at greater risk of pressure injury, such as rhabdomyolysis and compartment syndrome. Despite the association between obesity and several chronic disease states, the effects of obesity on perioperative outcomes are conflicting. Studies examining outcomes of overweight and obese patients in cardiac surgery have reported varying results. An "obesity paradox" has been described, in which the mortality for overweight and obese patients is lower compared with patients of normal weight. This review describes the physiologic abnormalities and clinical implications of obesity in cardiac surgery and summarizes recommendations for anesthesiologists to optimize perioperative care of the obese cardiac surgical patient.

Guidelines for the management of tracheal intubation in critically ill adults

These guidelines describe a comprehensive strategy to optimize oxygenation, airway management, and tracheal intubation in critically ill patients, in all hospital locations. They are a direct response to the 4^th National Audit Project of the Royal College of Anaesthetists and Difficult Airway Society, which highlighted deficient management of these extremely vulnerable patients leading to major complications and avoidable deaths. They are founded on robust evidence where available, supplemented by expert consensus opinion where it is not. These guidelines recognize that improved outcomes of emergency airway management require closer attention to human factors, rather than simply introduction of new devices or improved technical proficiency. They stress the role of the airway team, a shared mental model, planning, and communication throughout airway management. The primacy of oxygenation including pre- and peroxygenation is emphasized. A modified rapid sequence approach is recommended. Optimal management is presented in an algorithm that combines Plans B and C, incorporating elements of the Vortex approach. To avoid delays and task fixation, the importance of limiting procedural attempts, promptly recognizing failure, and transitioning to the next algorithm step are emphasized. The guidelines recommend early use of a videolaryngoscope, with a screen visible to all, and second generation supraglottic airways for airway rescue. Recommendations for emergency front of neck airway are for a scalpel-bougie-tube technique while acknowledging the value of other techniques performed by trained experts. As most critical care airway catastrophes occur after intubation, from dislodged or blocked tubes, essential methods to avoid these complications are also emphasized.