High-flow nasal oxygenation for anesthetic management

The comparison of preoxygenation methods before endotracheal intubation: a network meta-analysis of randomized trials

Background

Preoxygenation before endotracheal intubation (ETI) maintains asphyxiated oxygenation and reduces the risk of hypoxia-induced adverse events. Previous studies have compared various preoxygenation methods. However, network meta-analyses (NMAs) of the combined comparison of preoxygenation methods is still lacking.

Methods

We searched for studies published in PubMed, Embase, Web of Science, Scopus, and the Cochrane Library. Review Manager version 5.3 was used to evaluate the risk of bias. The primary outcome of this meta-analysis was low oxygen saturation (SpO2) during ETI. The secondary outcomes included SpO2 <80%, SpO2 <90%, and apnea time during ETI. NMA was performed using R 4.1.2 software gemtc packages in RStudio.

Results

A total of 15 randomized controlled trials were included in this study. Regarding the lowest SpO2, the noninvasive ventilation (NIV) with high-flow nasal cannula (HFNC) group performed better than the other groups. For SpO2 <80%, the NIV group (0.8603467) performed better than the HFNC (0.1373533) and conventional oxygen therapy (COT, 0.0023) groups, according to the surface under the cumulative ranking curve results. For SpO2 <90%, the NIV group (0.60932667) performed better than the HFNC (0.37888667) and COT (0.01178667) groups. With regard to apnea time, the HFNC group was superior to the COT group (mean difference: -50.05; 95% confidence interval: -90.01, -10.09; P = 0.01).

Conclusion

Network analysis revealed that NIV for preoxygenation achieved higher SpO2 levels than HFNC and COT and offered a more significant advantage in maintaining patient oxygenation during ETI. Patients experienced a longer apnea time after HFNC preoxygenation. The combination of NIV with HFNC proved to be significantly superior to other methods. Given the scarcity of such studies, further research is needed to evaluate its effectiveness.

Systematic review registration

identifier CRD42022346013.

High-flow nasal oxygenation versus face mask oxygenation for preoxygenation in patients undergoing double-lumen endobronchial intubation: protocol of a randomised controlled trial

INTRODUCTION

With the growing emphasis on swift recovery, minimally invasive thoracic surgery has advanced significantly. Video-assisted thoracoscopic surgery (VATS) has seen rapid development, and the double-lumen tube (DLT) remains the most dependable method for tracheal intubation in VATS. However, hypoxaemia during DLT intubation poses a threat to the perioperative safety of thoracic surgery patients. Recently, transnasal high-flow nasal oxygen (HFNO) has shown promise in anaesthesia, particularly in handling short-duration hypoxic airway emergencies. Yet, its application in the perioperative period for patients undergoing pulmonary surgery with compromised cardiopulmonary function lacks evidence, and there are limited reliable clinical data.

METHODS AND ANALYSIS

A prospective, randomised, controlled, single-blind design will be employed in this study. 112 patients aged 18-60 years undergoing elective VATS-assisted pulmonary surgery will be enrolled and randomly divided into two groups: the nasal high-flow oxygen group (H group) and the traditional mask transnasal oxygen group (M group) in a 1:1 ratio. HFNO will be used during DLT intubation for the prevention of asphyxia in group H, while conventional intubation procedures will be followed by group M. Comparison will be made between the two groups in terms of minimum oxygen saturation during intubation, hypoxaemia incidence during intubation, perioperative complications and postoperative hospital days.

ETHICS AND DISSEMINATION

Approval for this study has been granted by the local ethics committee at Shenzhen Second People's Hospital. The trial results will be disseminated through peer-reviewed journals and scientific conferences.

TRIAL REGISTRATION NUMBER

NCT05666908.

Rapid sequence induction of anesthesia: works in progress and steps forward with focus to oxygenation and monitoring techniques

The description of the main scientifically consolidated innovations in recent years on Rapid Sequence Induction have been the subject of this narrative review. Data sources were PubMed, EMBASE, Web of Science, the Cochrane Central Register of Controlled Trials, and ClinicaTrials.gov, searched up to March 21st, 2023; rapid sequence induction and anesthesia were used as key word for the research. In recent years at least three significant innovations which have improved the procedure: firstly the possibility of using drugs which rapidly reverse the action of the myorelaxants and which have made it possible to give up the use of succinylcholine, replaced by rocuronium; secondly, the possibility of using much more effective pre-oxygenation methods than in the past, also through apneic oxygenation techniques which allow longer apnea time, and finally new monitoring systems much more effective than pulse oximetry in identifying and predicting periprocedural hypoxemia and indicating the need for ventilation in patients at risk of hypoxemia and preventing it. The description of three main scientifically consolidated innovations in recent years, in pharmacology, oxygen method of administration and monitoring, have been the subject of this narrative review.

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.

Personalized Noninvasive Respiratory Support in the Perioperative Setting: State of the Art and Future Perspectives

Background: Noninvasive respiratory support (NRS), including high-flow nasal oxygen therapy (HFNOT), noninvasive ventilation (NIV) and continuous positive airway pressure (CPAP), are routinely used in the perioperative period. Objectives: This narrative review provides an overview on the perioperative use of NRS. Preoperative, intraoperative, and postoperative respiratory support is discussed, along with potential future areas of research. Results: During induction of anesthesia, in selected patients at high risk of difficult intubation, NIV is associated with improved gas exchange and reduced risk of postoperative respiratory complications. HFNOT demonstrated an improvement in oxygenation. Evidence on the intraoperative use of NRS is limited. Compared with conventional oxygenation, HFNOT is associated with a reduced risk of hypoxemia during procedural sedation, and recent data indicate a possible role for HFNOT for intraoperative apneic oxygenation in specific surgical contexts. After extubation, "preemptive" NIV and HFNOT in unselected cohorts do not affect clinical outcome. Postoperative "curative" NIV in high-risk patients and among those exhibiting signs of respiratory failure can reduce reintubation rate, especially after abdominal surgery. Data on postoperative "curative" HFNOT are limited. Conclusions: There is increasing evidence on the perioperative use of NRS. Use of NRS should be tailored based on the patient's specific characteristics and type of surgery, aimed at a personalized cost-effective approach.

Efficacy of a surgical mask during high-flow nasal oxygen therapy in preventing aerosol dispersion: a randomized controlled study

PURPOSE

It is not clear whether or not high-flow nasal oxygenation used in patients with severe respiratory tract infection, or coughing, increases the risk of infection to the healthcare personnel, and whether or not applying a surgical mask to the patient's face or treating the patient in a negative-pressure room can reduce the risk.

METHODS

In a randomized crossover design, we compared in 50 participants receiving high-flow nasal oxygenation, the aerosol counts measured at approximately 20 cm above the participant's mouth in 32 different circumstances (with or without coughing, with or without wearing a surgical mask, at four different flow rates of oxygenation, in a positive- or negative-pressure operating room).

RESULTS

In a positive-pressure room, a surgical mask significantly decreased the aerosol counts during coughing (P = 0.0005), or during no coughing (P = 0.009), under high-flow nasal oxygenation (at 60 l.min-1). In the negative-pressure room, the aerosol count was significantly lower than in the positive-pressure room, for all the circumstances (all P < 0.001), and a surgical mask significantly decreased the aerosol counts during coughing (P = 0.047) but not during no coughing (P = 0.60).

CONCLUSION

In conclusion, treating a patient in a negative-pressure room, or applying a surgical mask, during high-flow nasal oxygenation (with the flow rate of 60 l.min-1) would inhibit, but would not completely prevent, dispersion of aerosols by coughing.

Trans-nasal humidified rapid insufflation ventilatory exchange (THRIVE) in neuroanesthesia practice: A review

Respiratory management is an important aspect of care in neuroanesthesia practice for neurosurgical patients. A wide variety of procedures are performed under sedation in the neurosurgical population, and maintaining oxygenation is of paramount importance during these procedures. The high-flow oxygen devices improve arterial oxygenation by providing higher inspiratory oxygen concentration and maintaining higher dynamic positive airway pressure. These devices have gained importance during the recent years with regard to enhancing patient safety. This narrative review focuses on the role of trans-nasal humidified rapid insufflation ventilatory exchange (THRIVE) and high-flow nasal oxygenation (HFNO) techniques in the neuroanesthesia practice and electroconvulsive therapy.

Efficacy of high-flow nasal oxygen during drug-induced sleep endoscopy in patients with obstructive sleep apnea

PURPOSE

High-flow nasal oxygenation (HFNO) can provide a low level of continuous positive airway pressure and alveolar recruitment. We aimed to compare the efficacy of pre-oxygenation with HFNO and low-flow nasal oxygenation (LFNO) during drug-induced sleep endoscopy (DISE).

METHODS

In the LFNO group, preoxygenation was performed for 10 min at 3 L·min-1. In the HFNO group, preoxygenation was performed for 10 min at 30 L·min-1 at a fraction of inspired oxygen of 100% using the Optiflow device. From the start of sedative administration to the end of DISE, vital signs were monitored continuously. The primary outcome was the lowest oxygen saturation (SpO2) during DISE.

RESULTS

Of 24 patients enrolled, 12 were randomly assigned to the LFNO and 12 to the HFNO groups. The prevalence of hypoxia events was 75% in the LFNO group and 58% in the HFNO group. The difference in lowest oxygen saturation between the two groups was not significant between the two groups (P=0.665). The lowest SpO2 during all procedures was comparable between the two groups (86.8 ± 6.5% in the LFNO group and 87.2 ± 8.0% in the HFNO group; P=0.912).

CONCLUSIONS

The findings suggest that HFNO may not be superior to LFNO as a preoxygenation tool to prevent hypoxia during DISE.

Addressing desaturation in a tracheal stenosis patient using the transnasal humidified rapid-insufflation ventilatory exchange technique during tracheostomy: A case report

RATIONALE

Transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) is used in tracheostomy but not in cases of airway obstruction. This case report explores the use of THRIVE for managing airway obstruction during tracheostomy in patients with subglottic and tracheal stenosis, thereby addressing the current knowledge gap and exploring its potential for airway management.

PATIENT CONCERNS

A 63-year-old female with subglottic and tracheal stenoses underwent tracheostomy. Multiple attempts to establish a patent airway were unsuccessful, and oxygen saturation dropped to 56%.

DIAGNOSIS

Endotracheal tube was directed toward the tracheal wall, causing airway obstruction.

INTERVENTIONS

THRIVE was administered to the patient. Subsequently, the tube position was adjusted to enhance ventilation.

OUTCOMES

The patient's oxygen saturation increased to 99%. The postoperative complications, including subcutaneous emphysema, pneumothorax, pneumomediastinum and pneumopericardium, resolved. The patient was discharged on postoperative day 9.

LESSONS

THRIVE could be considered a temporary measure to enhance oxygenation before initiating a definitive treatment strategy.

Comparison of preoxygenation efficiency measured by the oxygen reserve index between high-flow nasal oxygenation and facemask ventilation: a randomised controlled trial

BACKGROUND

High-flow nasal oxygenation and the oxygen reserve index (ORI), which is a non-invasive and innovative modality that reflects the arterial oxygen content, are used in general anaesthesia. This study compares the preoxygenation efficiency (measured by the ORI) of high-flow nasal oxygenation and facemask ventilation during the induction process.

METHODS

This single-centre, two-group, randomised controlled trial included 197 patients aged ≥ 20 years who underwent orotracheal intubation for general anaesthesia for elective surgery. The patients were randomly allocated to receive preoxygenation via facemask ventilation or high-flow nasal oxygenation. The ORI was measured and compared between both groups.

RESULTS

The ORI increased during preoxygenation in all patients. At 1 min of preoxygenation, the ORI was significantly higher in the high-flow nasal oxygenation group (0.34 ± 0.33) than in the facemask ventilation group (0.21 ± 0.28; P = 0.003). The highest ORI was not significantly different between the two groups (0.68 ± 0.25 in the high-flow nasal oxygenation group vs. 0.70 ± 0.28 in the facemask ventilation group; P = 0.505).

CONCLUSIONS

High-flow nasal oxygenation results in an oxygenation status similar to that provided by facemask ventilation during the induction process of general anaesthesia; therefore, high-flow nasal oxygenation is a feasible preoxygenation method.

TRIAL REGISTRATION

Clinicaltrials.gov (NCT04291339).

Tube or tubeless: an anesthetic strategy for upper airway surgery

Since the patient's airway is shared between an anesthesiologist and a surgeon, airway management during upper airway surgery can be challenging. Beyond the conventional method of general anesthesia, high-flow nasal oxygenation (HFNO) has recently been used as a key technique for tubeless anesthesia. HFNO provides humidified, heated oxygen up to 70 L/min, which promises improved oxygenation and ventilation, allowing for prolonged apneic oxygenation. In previous physiological and clinical studies, HFNO has been demonstrated that tubeless anesthesia safely provide an uninterrupted surgical field during laryngeal surgeries. Although tubeless anesthesia remains uncommon, it can be a good alternative to conventional anesthesia if an anesthesiologist and a surgeon select appropriate patients together with sufficient experience. A safe strategy for tubeless anesthesia, along with appropriate backup plans, including endotracheal intubation and high-frequency jet ventilation, should be considered for upper airway surgery.

Spontaneous Ventilation With High-Flow Nasal Oxygen for Elective Suspension Microlaryngoscopy

Objective

Spontaneous ventilation under intravenous anesthesia allows the surgeon to work without interruption or obstruction of the operating field during suspension microlaryngoscopy (SML). High-flow nasal oxygen therapy (HFNO) is increasingly used in anesthesia. We hypothesized that its use during SML would increase patient safety even in situations where the airway is compromised by tumor or stenosis.

Study Design

Retrospective observational study.

Setting

University Hospital of Lausanne, Switzerland.

Methods

Adults patients who were scheduled for elective microlaryngeal surgery and managed with HFNO in spontaneous ventilation under general anesthesia between October 2020 and December 2021.

Results

Twenty-seven patients for a total of 32 surgical procedures were performed under HFNO with spontaneous ventilation. Seventy-five percent of the patients had respiratory symptoms. Twelve patients (42.9%) were planned for the treatment of subglottic or tracheal stenosis and 5 patients were managed for vocal cord cancer (18.5%). Out of 32 surgeries, 4 cases of saturation < 92% occurred, 3 of them during the decrease of the fraction of inspired oxygen to 30% for the use of the laser. In 3 cases, the patients were intubated to correct the hypoxemia.

Conclusion

Spontaneous respiration using intravenous anesthesia and high-flow nasal oxygen is a modern technique that increases patient safety while allowing the surgeon to work without interruption or imputation of the operative field during SML. This approach is particularly promising for the management of airways compromised by tumors or laryngotracheal stenosis.

Comparisons on the intraoperative desaturation and postoperative outcomes in non-intubated video-assisted thoracic surgery with supraglottic airway devices or high-flow nasal oxygen: A retrospective study

BACKGROUND

Few studies have compared intraoperative oxygenation and perioperative outcomes between non-intubated video-assisted thoracic surgery (NIVATS) with supraglottic airway devices (SADs) and NIVATS with high flow nasal oxygenation (HFNO). The aim of this retrospective study was to compare the intraoperative desaturation rate and postoperative outcomes between NIVATS with SADs and NIVATS with HFNO.

METHODS

Data regarding NIVATS performed for lung cancer from January 2020 to December 2021 were collected. Intraoperative anesthetic results, post-anesthetic adverse effects, and surgical outcomes for patients who received SAD or HFNO were analyzed using propensity score-matched and unmatched analysis.

RESULTS

In total, 199 patients with i-gel™ and 95 patients with HFNO were included. Significantly more female patients (91.6 vs. 82.4%, p = 0.0378) and fewer wedge resections (78.9 vs. 85.4%, p = 0.0258) were observed in the HFNO group. Among 250 patients who underwent NIVATS wedge resections under total intravenous anesthesia, those who received HFNO had a significantly higher desaturation event rate (19.8% vs. 7.9% in i-gel™ group; p = 0.0063), lower nadir SPO₂ (94.0% vs. 96.1% in i-gel™ group; p = 0.0012), and longer hospitalization (4.0 ± 0.8 vs. 3.6 ± 0.6 in i-gel™ group; p < 0.0001). However, propensity score matching analysis revealed no significant between-group difference in the desaturation rate. A log-rank test revealed that smoking (p = 0.0005) and HFNO (p = 0.0074) were associated with intraoperative desaturation.

CONCLUSION

The rate of SAD use in NIVATS was twice the rate of HFNO use, especially for wedge resections. There is uncertain airway patency and limited flow through HFNO during one-lung ventilation, whereas SADs like i-gel™ presented a significantly less intraoperative desaturation rate over time and similar postoperative outcomes.

Effect of High-Flow Nasal Oxygenation on Gastric Insufflation in Patients Undergoing Laryngeal Microsurgery under Tubeless General Anesthesia with Neuromuscular Blockade

BACKGROUND

High-flow nasal oxygenation is an oxygen delivery method by which high concentrations of heated humidified oxygen are supplied via the nasal cavity. This study aimed to investigate the effect of high-flow nasal oxygenation on gastric volume change in adult patients undergoing laryngeal microsurgery under tubeless general anesthesia with neuromuscular blockade.

METHODS

Patients aged 19-80 years with an American Society of Anesthesiologists physical status 1 or 2 who were scheduled to undergo laryngoscopic surgery under general anesthesia were recruited. Patients received high-flow nasal oxygenation therapy at 70 L/min during surgery under general anesthesia with neuromuscular blockade. The cross-sectional area of the gastric antrum was measured via ultrasound in the right lateral position before and after high-flow nasal oxygenation, and the gastric volume was calculated. The duration of apnea, i.e., the duration of administration of high-flow nasal oxygenation in the paralyzed state, was also recorded.

RESULTS

Of the 45 patients enrolled, 44 completed the study. There were no significant differences in the antral cross-sectional area in the right lateral position, gastric volume, and gastric volume per kg between before and after high-flow nasal oxygenation application. The median duration of apnea was 15 (interquartile range, 14-22) min.

CONCLUSION

High-flow nasal oxygenation at 70 L/min during apnea with the mouth open did not influence the gastric volume in patients undergoing laryngeal microsurgery under tubeless general anesthesia with neuromuscular blockade.

Utility of high-flow nasal oxygen in comparison to conventional oxygen therapy during upper gastrointestinal endoscopic procedures under sedation: A systematic review and meta-analyses

BACKGROUND

Sedation and analgesia are the integral components of modern-day upper gastrointestinal (GI) endoscopic procedures. Irrespective of the sedative agent, hypoxia is the most commonly encountered unwarranted event with sedation. The current study intends to scrutinize whether high-flow nasal oxygen (HFNO) is advantageous for providing respiratory support during upper GI endoscopic procedures over other conventional low-flow oxygen delivery modalities, e.g. nasal cannula, facemask, etc. METHODS: An extensive screening of electronic databases was done till July 31, 2022, after enlisting in International prospective register of systematic reviews (PROSPERO) (CRD42021245409). Randomized controlled trials (RCT), comparative cohort studies, case series, cross-sectional studies and case-control studies evaluating the utility of HFNO during upper GI endoscopy under sedation were included in this meta-analysis.

RESULTS

We retrieved eight randomized control studies and one longitudinal study with 3294 patients. The application of HFNO during endoscopy led to lesser incidence of desaturation spells (odds ratio [OR] = 0.23; 95% CI 0.11-0.48; I² = 71%), reduced procedural interruption (OR = 0.11; 95% CI 0.02-0.60; I² = 88%), better nadir SpO² level during procedure (mean difference [MD] = 3.16; 95% CI 0.54-5.78; I² = 73%), overall lesser incidence of sedation-related adverse events (OR = 0.63; 95% CI 0.42-0.93; I² = 25%), with no significant impact on the duration of endoscopy (MD = 0.15; 95% CI - 0.02 to 0.31, I² = 0%).

CONCLUSION

HFNO is a novel option for upper GI endoscopy under sedation.

CLINICAL TRIAL NUMBER AND REGISTRY URL

CRD42021245409 ( https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021245409 ).

High-Flow Nasal Oxygenation and Its Applicability in COVID Patients

High-flow nasal oxygenation (HFNO) is a type of oxygen therapy that provides humidified and heated oxygen through a nasal cannula at much higher flow rates than standard oxygen therapy, while also allowing control over the fraction of inspired oxygen (FIO₂). Compared to standard oxygen therapy, it is much more comfortable for the patient and seems to alleviate most of the problems associated with standard oxygen therapy, such as dry nose, dry throat and nasal pain. It also provides a variety of benefits that can reduce the incidence of escalating treatment and initiating mechanical ventilation in COVID patients with acute hypoxemic respiratory failure (AHRF). This article provides an overview of HFNO and its current applications in COVID patients during the pandemic.

Medium-Flow Oxygenation Through Facial Mask and Nasal Cannula in a Limited Resource Setting

Introduction: In centers with limited resources, a high flow nasal cannula is not available, thus we assess if preoxygenation with 15L flow of O2 available from anesthesia machines can prolong the safety period of induction of anesthesia before intubation and provide more time for securing the airway. Moreover, we compared the preoxygenation with standard 6L vs. 15L O2 through a facemask or a nasal cannula. Material and methods: Patients were allocated into four groups. Group I patients were preoxygenated with a nasal cannula on 6L of oxygen, patients in group II were preoxygenated with a nasal cannula on 15L of oxygen, patients in group III were preoxygenated with a facemask on 6L of oxygen, and patients in group IV were preoxygenated with a facemask on 15L of oxygen. The primary endpoint was time to desaturation and intubation. The secondary endpoints were PaO2, PaCO2, Sat% and ETCO2. Results: The groups with 15L preoxygenation had a statistically significant prolonged time to desaturation and intubation. Patients allocated to group II have a statistically significant greater PaO2 and lesser ETCO2 compered with group I. However, between patients in group III and IV there is a difference only in PaCO2, and although this effect is significant, both groups have values within the normal range. Conclusion: In centers with limited resources, preoxygenation with the maximum available oxygen flow from anesthesia machines (15L/min) are useful. This prolongs the safety period for securing the airway. We suggest the use of the maximum available amount of oxygen flow from anesthesia machines in clinical settings.

Apnoeic oxygenation with high-flow oxygen for tracheal resection and reconstruction surgery

Background

Tracheal resection and reconstruction are the most effective treatments for tracheal stenosis, but the difficulties are surgery and maintaining ventilation performed on the patient’s same airway. High-flow oxygen has begun to be applied to prolong the apnoea time in the tracheal anastomosis period for tracheal resection and reconstruction. This study aims to evaluate the effectiveness of apneic conditions with high-flow oxygen as the sole method of gas exchange during anastomosis construction.

Methods

A prospective study was performed on 16 patients with tracheal stenosis, with ages ranging from 19 to 70, who underwent tracheal resection and reconstruction from April 2019 to August 2020 in 108 Military Central Hospital. During the anastomosis phase using high flow oxygen of 35–40 l.min-1 delivered across the open tracheal with an endotracheal tube (ETT) at the glottis in apnoeic conditions.

Results

The mean (SD) apnoea time was 20.91 (2.53) mins. Mean (SD) time anastomosis was 22.9 (2.41) mins. The saturation of oxygen was stable during all procedures at 98–100%. Arterial blood gas analysis showed mean (SD) was hypercapnia and acidosis acute respiratory after 10 mins of apnoea and 20 mins apnoea respectively. However, after 15 mins of ventilation, the parameters are ultimately returned to normal. All 16 patients were extubated early and safely at the end of the operation. There were no complications, such as bleeding, hemothorax, pneumothorax, or barotrauma.

Conclusion

High-flow oxygen across the open tracheal under apnoeic conditions can provide a satisfactory gas exchange to allow tubeless anesthesia for tracheal resection and reconstruction.

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.

High-flow nasal cannula application in an infant patient with laryngomalacia during general anesthesia: A case report

RATIONALE

Laryngomalacia is defined as the collapse of supraglottic structures and can cause not only strider but also trigger difficulties with ventilation and endotracheal intubation during anesthesia management. High-flow nasal cannula (HFNC) has been used to manage patients at high risk of hypoxemia in the intensive care unit; however, limited literature information is available for the application of HFNC to infant patients with laryngomalacia during anesthesia practice.

PATIENT CONCERNS

A 2-month-old male infant was scheduled to undergo surgery for inguinal hernia and undescended testis with general anesthesia.

DIAGNOSIS

The patient had subcostal retraction while breathing and frequent oxygen desaturation events and was diagnosed laryngomalacia.

INTERVENTIONS

After the patient was supplied oxygen via HFNC and then given general anesthesia, the initial 2 attempts of endotracheal intubation with a rigid laryngoscope were unsuccessful because the vocal cords were obscured by the epiglottis. A third intubation attempt was performed and successful with a 3.0-sized, uncuffed endotracheal tube within 20 minutes of the initial attempt.

OUTCOMES

No airway complications emerged and oxygen saturation remained at greater than 98% during general anesthesia. The patient was discharged 5 days after surgery without any adverse side effects.

LESSONS

Continuous oxygenation via HFNC is a good choice to prevent desaturation during difficult tracheal intubations in infant patients with laryngomalacia. This device is expected to be useful for intubation not only in patients with laryngomalacia, but also in infant patients with a predicted high risk of oxygen desaturation events during general anesthesia.

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.

Airway management in a patient with an intratracheal tumor near the carina by a two-stage operation

In patients with intratracheal tumors, airway management while maintaining oxygenation and providing surgical access to the airway can be challenging. Here, we present a case of a two-stage operation to remove an intratracheal tumor causing partial obstruction near the carina. In the otorhinolaryngology department, a biopsy was performed during apnea under high-flow nasal oxygenation support. A few days later, a thoracic surgeon performed tracheal resection after sternotomy under general anesthesia. Mechanical ventilation was performed by inserting a sterile endotracheal tube in the resected distal part of the trachea in the surgical field for tracheal end-to-end anastomosis. Airway was successfully secured through close communication between teams of anesthesiologists and surgeons.

Application of high-flow nasal oxygenation as a rescue therapy in difficult videolaryngoscopic intubation

In difficult airway situations, the next step of the airway management method is selected according to the prior presence of difficulties in mask ventilation and endotracheal intubation. It is important for the practitioner to be calm, quick in judgment, and take action in cases of difficult intubation. Recently, high-flow nasal oxygenation has been rapidly introduced into the anesthesiology field. This technique could extend the safe apnea time to desaturation. Especially, it maintains adequate oxygenation even in apnea and allows time for intubation or alternative airway management. We report two cases in which high-flow nasal oxygenation was implemented in the middle of the induction process after quick judgment by clinicians. High-flow nasal oxygenation was successfully used to assist in prolonging the safe apnea time during delicate airway securing attempts.

A comparison of gastric gas volumes measured by computed tomography after high-flow nasal oxygen therapy or conventional facemask ventilation. Anaesthesia 2021;76:1184-1189. [PMID: 33651914 DOI: 10.1111/anae.15433]

High-flow nasal oxygen therapy is increasingly used to improve peri-intubation oxygenation. However, it is unknown whether it may cause or exacerbate insufflation of gas into the stomach. High-flow nasal oxygen therapy is now standard practice in our hospital for adult patients undergoing percutaneous thermal ablation of liver cancer under general anaesthesia with tracheal intubation. We compared gastric gas volumes measured from computed tomography images that had been acquired immediately after intubation in two series of patients: 50 received peri-intubation high-flow nasal oxygen therapy and another 50 received conventional facemask pre-oxygenation and ventilation before intubation and before high-flow nasal oxygen therapy became standard practice in our unit. Median (IQR [range]) gastric gas volume was 24.0 (14.2-59.9 [3-167]) cm³ in the high-flow nasal oxygen therapy group and 23.8 (12.6-38.8 [0-185]) cm³ in the facemask group. There was no difference between the two groups in the volume of gastric gas measured by computed tomography imaging (Mann-Whitney U-test, U = 1136, p = 0.432, n₁  = n₂  = 50). Our results demonstrate that a small volume of gastric gas is commonly present after induction of anaesthesia, but that the use of peri-intubation high-flow nasal oxygen therapy for pre-oxygenation and during apnoea does not increase this volume compared with conventional facemask pre-oxygenation and ventilation. This is clinically relevant, as high-flow nasal oxygen therapy is increasingly being used in a peri-intubation context and in patients at higher risk of aspiration.

Airway Management with Dexmedetomidine and High-Flow Nasal Cannula in a Patient with Deep Neck Infection

Retropharyngeal deep neck infection sometimes necessitates securing of the airway and surgery for drainage. Airway management in patients with deep neck infection is challenging for anesthesiologists. A 56-year-old woman diagnosed with deep neck infection was admitted for incision and drainage. In the first operation for incision and drainage, indirect videolaryngoscope was utilized to confirm the airway before tracheal intubation, and the patient was intubated successfully. In the second operation for wound closure, dexmedetomidine administration and high-flow nasal cannulation were used during monitored anesthesia care throughout a subsequent procedure. The outcome in the present case suggests that indirect videolaryngoscope, dexmedetomidine, and high-flow nasal cannula can facilitate effective management during surgery in patients with retropharyngeal deep neck space infection.

Aligning difficult airway guidelines with the anesthetic COVID-19 guidelines to develop a COVID-19 difficult airway strategy: a narrative review

The coronavirus disease 2019 (COVID-19) pandemic is caused by a coronavirus that is transmitted primarily via aerosol, droplets or direct contact. This may place anesthetists at higher risk of infection due to their frequent involvement in aerosol-generating airway interventions. Many anesthethetic COVID-19 guidelines have emerged, whose underlying management principles include minimizing aerosol contamination and protecting healthcare workers. These guidelines originate from Australia and New Zealand, Canada, China, India, Italy, Korea, Singapore, the United States and the United Kingdom. Hospitalized COVID-19 patients may require airway interventions, and difficult tracheal intubation secondary to laryngeal edema has been reported. Pre-pandemic difficult airway guidelines include those from Canada, France, Germany, India, Japan, Scandinavia, the United States and the United Kingdom. These difficult airway guidelines require modifications in order to align with the principles of the anesthetic COVID-19 guidelines. In turn, most of the anesthetic COVID-19 guidelines do not, or only briefly, discuss an airway strategy after failed tracheal intubation. Our article identifies and compares pre-pandemic difficult airway guidelines with the recent anesthetic COVID-19 guidelines. We combine the principles from both sets of guidelines and explain the necessary modifications to the airway guidelines, to form a failed tracheal intubation airway strategy in the COVID-19 patient. Valuing, and a greater understanding of, these differences and modifications may lead to greater adherence to the new COVID-19 guidelines.

High-Flow Nasal Cannula Oxygen Therapy Can Be Effective for Patients in Acute Hypoxemic Respiratory Failure with Hypercapnia: a Retrospective, Propensity Score-Matched Cohort Study

BACKGROUND

Usually, high-flow nasal cannula (HFNC) therapy is indicated for de novo acute hypoxemic respiratory failure (AHRF). Although only a few researches have examined the effectiveness of HFNC therapy for respiratory failure with hypercapnia, this therapy is often performed under such conditions for various reasons. We investigated the effectiveness of HFNC therapy for AHRF patients with hypercapnia compared to those without hypercapnia.

METHODS

All consecutive patients receiving HFNC therapy between January 2012 and June 2018 at a university hospital were enrolled and classified into nonhypercapnic and hypercapnic groups. We compared the outcomes of both groups and adjusted the outcomes with propensity score matching.

RESULTS

A total of 862 patients were enrolled, of which 202 were included in the hypercapnic group. HFNC weaning success rates were higher, and intensive care unit (ICU) and hospital mortality was lower in the hypercapnic group than in the nonhypercapnic group (all P < 0.05). However, no statistical differences in HFNC weaning success (adjusted P = 0.623, matched P = 0.593), ICU mortality (adjusted P = 0.463, matched P = 0.195), and hospital mortality (adjusted P = 0.602, matched P = 0.579) were noted from the propensity-adjusted and propensity-matched analyses. Additionally, in the propensity score-matched subgroup analysis (according to chronic lung diseases and causes of HFNC application), there was also no significant difference in outcomes between the two groups.

CONCLUSION

In AHRF with underlying conditions, HFNC therapy might be helpful for patients with hypercapnia. Large prospective and randomized controlled trials are required for firm conclusions.