Effect of Apneic Oxygenation on Tracheal Oxygen Levels, Tracheal Pressure, and Carbon Dioxide Accumulation: A Randomized, Controlled Trial of Buccal Oxygen Administration

Effect of high-flow nasal and buccal oxygenation on safe apnea time in children with open mouth: A randomized controlled trial

BACKGROUND

High-flow nasal oxygenation is reported to prolong duration of apnea while maintaining adequate oxygen saturation with the mouth closed. Also, buccal oxygenation is known to have similar effects in obese adults. We compared the effect of these two methods on prolongation of acceptable apnea time in pediatric patients with their mouth open.

METHODS

Thirty-eight patients, aged 0-10 years were randomly allocated to either the high-flow nasal oxygenation group (n = 17) or the buccal oxygenation group (n = 21). After induction of anesthesia including neuromuscular blockade, manual ventilation was initiated until the expiratory oxygen concentration reached 90%. Subsequently, ventilation was paused, and the patient's head was extended, and mouth was opened. The HFNO group received 2 L·min-1·kg-1 of oxygen, and the BO group received 0.5 L·min-1·kg-1 of oxygen. We set a target apnea time according to previous literature. When the apnea time reached the target, we defined the case as "success" in prolongation of safe apnea time and resumed ventilation. When the pulse oximetry decreased to 92% before the target apnea time, it was recorded as "failure" and rescue ventilation was given.

RESULTS

The success rate of safe apnea prolongation was 100% in the high-flow nasal oxygenation group compared to 76% in the buccal oxygenation group (p = .04). Oxygen reserve index, end-tidal or transcutaneous carbon dioxide partial pressure, and pulse oximetry did not differ between groups.

CONCLUSION

High-flow nasal oxygenation is effective in maintaining appropriate arterial oxygen saturation during apnea even in children with their mouth open and is superior to buccal oxygenation. Buccal oxygenation may be a good alternative when high-flow nasal oxygenation is not available.

Transnasal humidified rapid-insufflation ventilator exchange compared with laryngeal mask airway for endoscopic thoracic sympathectomy: a randomized controlled trial

Background

Transnasal humidified rapid-insufflation ventilator exchange (THRIVE) has the characteristics of operating easily and maintaining oxygenation and eliminating CO2, which makes it possible to be used in endoscopic thoracic sympathectomy (ETS). The application of THRIVE in ETS remains undefined. The purpose of this randomized controlled study is to assess the efficacy between THRIVE and laryngeal mask airway (LMA) for ETS.

Methods

In total, 34 patients from May 2022 to May 2023 in Huazhong University of Science and Technology Union Shenzhen Hospital undergoing ETS were randomly divided into a THRIVE group (n = 17) and an LMA group (n = 17). A serial arterial blood gas analysis was conducted during the perioperative period. The primary outcome was the arterial partial pressure of carbon dioxide (PaCO2) during the perioperative period. The secondary outcome was arterial partial pressure of oxygen (PaO2) during the perioperative period.

Results

The mean (SD) highest PaCO2 in the THRIVE group and LMA group were 99.0 (9.0) mmHg and 51.7 (5.2) mmHg, respectively (p < 0.001). The median (inter-quartile range) time to PaCO2 ≥ 60 mmHg in the THRIVE group was 26.0 min (23.2-28.8). The mean (SD) PaO2 was 268.8 (89.0) mmHg in the THRIVE group and 209.8 (55.8) mmHg in the LMA group during surgery (p = 0.027).

Conclusion

CO2 accumulation in the THRIVE group was higher than that of the LMA group during ETS, but THRIVE exhibited greater oxygenation capability compared to LMA. We preliminarily testified that THRIVE would be a feasible non-intubated ventilation technique during ETS under monitoring PaCO2.

Oxygenation during the apnoeic phase preceding intubation in adults in prehospital, emergency department, intensive care and operating theatre environments

BACKGROUND

Apnoeic oxygenation is the delivery of oxygen during the apnoeic phase preceding intubation. It is used to prevent respiratory complications of endotracheal intubation that have the potential to lead to significant adverse events including dysrhythmia, haemodynamic decompensation, hypoxic brain injury and death. Oxygen delivered by nasal cannulae during the apnoeic phase of intubation (apnoeic oxygenation) may serve as a non-invasive adjunct to endotracheal intubation to decrease the incidence of hypoxaemia, morbidity and mortality.

OBJECTIVES

To evaluate the benefits and harms of apnoeic oxygenation before intubation in adults in the prehospital, emergency department, intensive care unit and operating theatre environments compared to no apnoeic oxygenation during intubation.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 4 November 2022.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) and quasi-RCTs that compared the use of any form of apnoeic oxygenation including high flow and low flow nasal cannulae versus no apnoeic oxygenation during intubation. We defined quasi-randomization as participant allocation to each arm by means that were not truly random, such as alternation, case record number or date of birth. We excluded comparative prospective cohort and comparative retrospective cohort studies, physiological modelling studies and case reports.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were 1. hospital stay and 2. incidence of severe hypoxaemia. Our secondary outcomes were 3. incidence of hypoxaemia, 4. lowest recorded saturation of pulse oximetry (SpO2), 5. intensive care unit (ICU) stay, 6. first pass success rate, 7. adverse events and 8.

MORTALITY

We used GRADE to assess certainty of evidence.

MAIN RESULTS

We included 23 RCTs (2264 participants) in our analyses. Eight studies (729 participants) investigated the use of low-flow (15 L/minute or less), and 15 studies (1535 participants) investigated the use of high-flow (greater than 15 L/minute) oxygen. Settings were varied and included the emergency department (2 studies, 327 participants), ICU (7 studies, 913 participants) and operating theatre (14 studies, 1024 participants). We considered two studies to be at low risk of bias across all domains. None of the studies reported on hospital length of stay. In predominately critically ill people, there may be little to no difference in the incidence of severe hypoxaemia (SpO2 less than 80%) when using apnoeic oxygenation at any flow rate from the start of apnoea until successful intubation (risk ratio (RR) 0.86, 95% confidence interval (CI) 0.66 to 1.11; P = 0.25, I² = 0%; 15 studies, 1802 participants; low-certainty evidence). There was insufficient evidence of any effect on the incidence of hypoxaemia (SpO2 less than 93%) (RR 0.58, 95% CI 0.23 to 1.46; P = 0.25, I² = 36%; 3 studies, 489 participants; low-certainty evidence). There may be an improvement in the lowest recorded oxygen saturation, with a mean increase of 1.9% (95% CI 0.75% to 3.05%; P < 0.001, I² = 86%; 15 studies, 1525 participants; low-certainty evidence). There may be a reduction in the duration of ICU stay with the use of apnoeic oxygenation during intubation (mean difference (MD) ‒1.13 days, 95% CI ‒1.51 to ‒0.74; P < 0.0001, I² = 46%; 5 studies, 815 participants; low-certainty evidence). There may be little to no difference in first pass success rate (RR 1.00, 95% CI 0.93 to 1.08; P = 0.79, I² = 0%; 8 studies, 826 participants; moderate-certainty evidence). There may be little to no difference in incidence of adverse events including oral trauma, arrhythmia, aspiration, hypotension, pneumonia and cardiac arrest when apnoeic oxygenation is used. There was insufficient evidence about any effect on mortality (RR 0.84, 95% CI 0.70 to 1.00; P = 0.06, I² = 0%; 6 studies, 1015 participants; low-certainty evidence).

AUTHORS' CONCLUSIONS

There was some evidence that oxygenation during the apnoeic phase of intubation may improve the lowest recorded oxygen saturation. However, the differences in oxygen saturation were unlikely to be clinically significant. This did not translate into any measurable effect on the incidence of hypoxaemia or severe hypoxaemia in a group of predominately critically ill people. We were unable to assess the influence on hospital length of stay; however, there was a reduction in ICU stay in the apnoeic oxygenation group. The mechanism for this is unclear as there was little to no difference in first pass success or adverse event rates.

Apnoeic oxygenation in morbid obesity: a randomised controlled trial comparing facemask and high-flow nasal oxygen delivery

BACKGROUND

Obesity is a risk factor for airway-related incidents during anaesthesia. High-flow nasal oxygen has been advocated to improve safety in high-risk groups, but its effectiveness in the obese population is uncertain. This study compared the effect of high-flow nasal oxygen and low-flow facemask oxygen delivery on duration of apnoea in morbidly obese patients.

METHODS

Morbidly obese patients undergoing bariatric surgery were randomly allocated to receive either high-flow nasal (70 L min^-1) or facemask (15 L min^-1) oxygen. After induction of anaesthesia, the patients were apnoeic for 18 min or until peripheral oxygen saturation decreased to 92%.

RESULTS

Eighty patients were studied (41 High-Flow Nasal Oxygen, 39 Facemask). The median apnoea time was 18 min in both the High-Flow Nasal Oxygen (IQR 18-18 min) and the Facemask (inter-quartile range [IQR], 4.1-18 min) groups. Five patients in the High-Flow Nasal Oxygen group and 14 patients in the Facemask group desaturated to 92% within 18 min. The risk of desaturation was significantly lower in the High-Flow Nasal Oxygen group (hazard ratio=0.27; 95% confidence interval [CI], 0.11-0.65; P=0.007).

CONCLUSIONS

In experienced hands, apnoeic oxygenation is possible in morbidly obese patients, and oxygen desaturation did not occur for 18 min in the majority of patients, whether oxygen delivery was high-flow nasal or low-flow facemask. High-flow nasal oxygen may reduce desaturation risk compared with facemask oxygen. Desaturation risk is a more clinically relevant outcome than duration of apnoea. Individual physiological factors are likely to be the primary determinant of risk rather than method of oxygen delivery.

CLINICAL TRIAL REGISTRATION

NCT03428256.

Apnoeic oxygenation using transnasal humidified rapid-insufflation ventilatory exchange during rigid bronchoscopy: a report of four cases

General anaesthesia with a muscle relaxant is usually performed for rigid bronchoscopy (RB), but ventilation is challenging due to large amounts of leakage. Optiflow™ supplies 100% humidified, warmed oxygen at a rate of up to 70 l/min and this high flow rate may overcome the leakage problem. This case report describes four patients that were scheduled for RB. The lung lesions were all located below the carina, so a bronchial tube was inserted under general anaesthesia. Once a large amount of leakage was confirmed by manual ventilation, Optiflow™ was connected to the bronchial tube (flow rate, 70 l/min). All of the ports of the bronchoscopy were left open to prevent the risk of outlet obstruction. Oxygenation was well maintained with stable vital signs throughout the procedures, which took up to 34 min without airway intervention. There were no occurrences of cardiac arrhythmia or changes in the electrocardiograms. Respiratory acidosis recovered after emergence, which was confirmed by arterial blood gas analysis in all cases. Apnoeic oxygenation using Optiflow™ was applied successfully during RB. Applying Optiflow™ could make cases of difficult ventilation during RB much easier for the anaesthetist. Larger studies need to demonstrate the efficacy and safety of this technique.

The Effect of High-Flow Nasal Oxygen on Carbon Dioxide Accumulation in Apneic or Spontaneously Breathing Adults During Airway Surgery: A Randomized-Controlled Trial

BACKGROUND

High-flow nasal oxygen (HFNO) is an emerging technology that has generated interest in tubeless anesthesia for airway surgery. HFNO has been shown to maintain oxygenation and CO2 clearance in spontaneously breathing patients and is an effective approach to apneic oxygenation. Although it has been suggested that HFNO can enhance CO2 clearance during apnea, this has not been established. The true extent of CO2 accumulation and resulting acidosis using HFNO during prolonged tubeless anesthesia remains undefined.

METHODS

In a single-center trial, we randomly assigned 20 adults undergoing microlaryngoscopy to apnea or spontaneous ventilation (SV) using HFNO during 30 minutes of tubeless anesthesia. Serial arterial blood gas analysis was performed during preoxygenation and general anesthesia. The primary outcome was the partial pressure of CO2 (Paco2) after 30 minutes of general anesthesia, with each group compared using a Student t test.

RESULTS

Nineteen patients completed the study protocol (9 in the SV group and 10 in the apnea group). The mean (standard deviation [SD]) Paco2 was 89.0 mm Hg (16.5 mm Hg) in the apnea group and 55.2 mm Hg (7.2 mm Hg) in the SV group (difference in means, 33.8; 95% confidence interval [CI], 20.6-47.0) after 30 minutes of general anesthesia (P < .001). The average rate of Paco2 rise during 30 minutes of general anesthesia was 1.8 mm Hg/min (SD = 0.5 mm Hg/min) in the apnea group and 0.8 mm Hg/min (SD = 0.3 mm Hg/min) in the SV group. The mean (SD) pH was 7.11 (0.04) in the apnea group and 7.29 (0.06) in the SV group (P < .001) at 30 minutes. Five (55%) of the apneic patients had a pH <7.10, of which the lowest measurement was 7.057. No significant difference in partial pressure of arterial O2 (Pao2) was observed after 30 minutes of general anesthesia.

CONCLUSIONS

CO2 accumulation during apnea was more than double that of SV after 30 minutes of tubeless anesthesia using HFNO. The use of robust measurement confirms that apnea with HFNO is limited by CO2 accumulation and the concomitant severe respiratory acidosis, in contrast to SV. This extends previous knowledge and has implications for the safe application of HFNO during prolonged procedures.

Apnoeic oxygenation during simulated difficult intubation in obese patients: comparison of buccal ring, adair and elwyn tube versus nasal cannula: A prospective randomized controlled trial

Background:

Apnoeic oxygenation is an established method of increasing safe apnoea times during intubation and this is of more importance in obese patients. The usefulness of buccal Ring, Adair and Elwyn (RAE) oxygenation has been established in previous studies, however a head-to-head comparison with nasal cannula (NC) is lacking.

Aim:

The aim of this study was to compare apnoea time with buccal RAE (BR) versus NC in obese patients.

Setting and Design:

This was a prospective, nonblinded randomized controlled trial conducted in a tertiary hospital where fifty American Society of Anaesthesiologists Physical Status Class I and II, obese patients with body mass index ≥30, posted for elective surgery were included.

Materials and Methods:

Following adequate preoxygenation and standard induction of anaesthesia, a prolonged simulated difficult laryngoscopy was performed during which oxygen was provided via either BR or NC. The primary outcome was time to desaturation to <95% or 10 min, which ever occurred first. Other outcomes recorded were lowest saturation, time to resaturation and highest end tidal carbon di oxide.

Statistical Analysis:

Mean with standard deviation (SD) or median with inter quartile range were used for continuous variables and absolute number with percentage were used for categorical variables. The primary outcome was analyzed using Kaplan-Meier survival curves, and log-rank tests were applied.

Results:

Patient characteristics were similar in both arms. The mean apnoea time in seconds (SD) in the BR group, 375.3 (116.6) was higher than the NC group 316.1 (94.1), P = 0.054. From the Kapan Meier curves the probability of desaturating to <95% was earlier in the NC group than the BR group (P = 0.092). The other outcomes were similar in both groups.

Conclusion:

This is the first study that demonstrates that oxygenation via a BR is better than NC in providing apnoeic oxygenation in obese patients and can safely be used when NC are contraindicated.

A novel application of Transnasal Humidified Rapid Insufflation Ventilatory Exchange via the oral route in morbidly obese patient during monitored anesthesia care - A case report

Background

Transnasal Humidified Rapid Insufflation Ventilatory Exchange (THRIVE) is used to improve oxygenation, with the added benefit of a smaller increase in CO₂ if self-respiration is maintained with THRIVE. Despite these advantages, the use of THRIVE through a nasal cannula is limited in situations such as epistaxis or a basal skull fracture.

Case

We successful used THRIVE, through the oral route under general anesthesia with spontaneous breathing in a morbidly obese patient (weight, 148 kg; height, 183 cm; body mass index, 44.2 kg/m²) who received transnasal steroid injections due to subglottic stenosis.

Conclusions

THRIVE through the oral route may be an effective novel option, although further studies are needed.

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.