Pre-oxygenation with high-flow oxygen through the nasopharyngeal airway compared to facemask on carbon dioxide clearance in emergency adults: a prospective randomized non-blinded clinical trial

INTRODUCTION

Before tracheal intubation, it is essential to provide sufficient oxygen reserve for emergency patients with full stomachs. Recent studies have demonstrated that high-flow nasal oxygen (HFNO) effectively pre-oxygenates and prolongs apneic oxygenation during tracheal intubation. Despite its effectiveness, the use of HFNO remains controversial due to concerns regarding carbon dioxide clearance. The air leakage and unknown upper airway obstruction during HFNO therapy cause reduced oxygen flow above the vocal cords, possibly weaken the carbon dioxide clearance.

METHODS

Patients requiring emergency surgery who had fasted < 8 h and not drunk < 2 h were randomly assigned to the high-flow group, who received 100% oxygen at 30-60 L/min through nasopharyngeal airway (NPA), or the mask group, who received 100% oxygen at 8 L/min. PaO2 and PaCO2 were measured immediately before pre-oxygenation (T0), anesthesia induction (T1), tracheal intubation (T2), and mechanical ventilation (T3). The gastric antrum's cross-sectional area (CSA) was measured using ultrasound technology at T0, T1, and T3. Details of complications, including hypoxemia, reflux, nasopharyngeal bleeding, postoperative pulmonary infection, postoperative nausea and vomiting (PONV), and postoperative nasopharyngeal pain, were recorded. The primary outcomes were PaCO2 measured at T1, T2, and T3. The secondary outcomes included PaO2 at T1, T2, and T3, CSA at T1 and T3, and complications happened during this trial.

RESULTS

Pre-oxygenation was administered by high-flow oxygen through NPA (n = 58) or facemask (n = 57) to 115 patients. The mean (SD) PaCO2 was 32.3 (6.7) mmHg in the high-flow group and 34.6 (5.2) mmHg in the mask group (P = 0.045) at T1, 45.0 (5.5) mmHg and 49.4 (4.6) mmHg (P < 0.001) at T2, and 47.9 (5.1) mmHg and 52.9 (4.6) mmHg (P < 0.001) at T3, respectively. The median ([IQR] [range]) PaO2 in the high-flow and mask groups was 404.5 (329.1-458.1 [159.8-552.9]) mmHg and 358.9 (274.0-413.3 [129.0-539.1]) mmHg (P = 0.007) at T1, 343.0 (251.6-428.7 [73.9-522.1]) mmHg and 258.3 (162.5-347.5 [56.0-481.0]) mmHg (P < 0.001) at T2, and 333.5 (229.9-411.4 [60.5-492.4]) mmHg and 149.8 (87.0-246.6 [51.2-447.5]) mmHg (P < 0.001) at T3, respectively. The CSA in the high-flow and mask groups was 371.9 (287.4-557.9 [129.0-991.2]) mm2 and 386.8 (292.0-537.3 [88.3-1651.7]) mm2 at T1 (P = 0.920) and 452.6 (343.7-618.4 [161.6-988.1]) mm2 and 385.6 (306.3-562.0 [105.5-922.9]) mm2 at T3 (P = 0.173), respectively. The number (proportion) of complications in the high-flow and mask groups is shown below: hypoxemia: 1 (1.7%) vs. 9 (15.8%, P = 0.019); reflux: 0 (0%) vs. 0 (0%); nasopharyngeal bleeding: 1 (1.7%) vs. 0 (0%, P = 1.000); pulmonary infection: 4 (6.9%) vs. 3 (5.3%, P = 1.000); PONV: 4 (6.9%) vs. 4 (7.0%, P = 1.000), and nasopharyngeal pain: 0 (0%) vs. 0 (0%).

CONCLUSIONS

Compared to facemasks, pre-oxygenation with high-flow oxygen through NPA offers improved carbon dioxide clearance and enhanced oxygenation prior to tracheal intubation in patients undergoing emergency surgery, while the risk of gastric inflation had not been ruled out.

TRIAL REGISTRATION

This trial was registered prospectively at the Chinese Clinical Research Registry on 26/4/2022 (Registration number: ChiCTR2200059192).

Transcutaneous carbon dioxide measurements in anesthetized apneic patients with BMI > 35 kg/m2

Transcutaneous carbon dioxide measurement (TcCO2) offers the ability to continuously and non-invasively monitor carbon dioxide (CO2) tensions when end-tidal monitoring is not possible. The accuracy of TcCO2 has not been established in anesthetized apneic patients with obesity. In this secondary publication, we present a methods comparison analysis of TcCO2 with the gold standard arterial PCO2, in adult patients with body mass index (BMI) > 35kg/m2 who were randomized to receive high flow or low flow nasal oxygenation during post-induction apnea. Agreement between PaCO2 and TcCO2 at baseline, the start of apnea and the end of apnea were assessed using a non-parametric difference plot. Forty-two participants had a median (IQR) BMI of 52 (40-58.5) kg/m2. The mean (SD) PaCO2 was 33.9 (4.0) mmHg at baseline and 51.4 (7.5) mmHg at the end of apnea. The bias was the greatest at the end of apnea median (95% CI, 95% limits of agreement) 1.90 mmHg (-2.64 to 6.44, -7.10 to 22.90). Findings did not suggest significant systematic differences between the PaCO2 and TcCO2 measures. For a short period of apnea, TcCO2 showed inadequate agreement with PaCO2 in patients with BMI > 35 kg/m2. These techniques require comparison in a larger population, with more frequent sampling and over a longer timeframe, before TcCO2 can be confidently recommended in this setting.

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).

Effect of apneic oxygenation with intubation to reduce severe desaturation and adverse tracheal intubation-associated events in critically ill children

BACKGROUND

Determine if apneic oxygenation (AO) delivered via nasal cannula during the apneic phase of tracheal intubation (TI), reduces adverse TI-associated events (TIAEs) in children.

METHODS

AO was implemented across 14 pediatric intensive care units as a quality improvement intervention during 2016-2020. Implementation consisted of an intubation safety checklist, leadership endorsement, local champion, and data feedback to frontline clinicians. Standardized oxygen flow via nasal cannula for AO was as follows: 5 L/min for infants (< 1 year), 10 L/min for young children (1-7 years), and 15 L/min for older children (≥ 8 years). Outcomes were the occurrence of adverse TIAEs (primary) and hypoxemia (SpO₂ < 80%, secondary).

RESULTS

Of 6549 TIs during the study period, 2554 (39.0%) occurred during the pre-implementation phase and 3995 (61.0%) during post-implementation phase. AO utilization increased from 23 to 68%, p < 0.001. AO was utilized less often when intubating infants, those with a primary cardiac diagnosis or difficult airway features, and patient intubated due to respiratory or neurological failure or shock. Conversely, AO was used more often in TIs done for procedures and those assisted by video laryngoscopy. AO utilization was associated with a lower incidence of adverse TIAEs (AO 10.5% vs. without AO 13.5%, p < 0.001), aOR 0.75 (95% CI 0.58-0.98, p = 0.03) after adjusting for site clustering (primary analysis). However, after further adjusting for patient and provider characteristics (secondary analysis), AO utilization was not independently associated with the occurrence of adverse TIAEs: aOR 0.90, 95% CI 0.72-1.12, p = 0.33 and the occurrence of hypoxemia was not different: AO 14.2% versus without AO 15.2%, p = 0.43.

CONCLUSION

While AO use was associated with a lower occurrence of adverse TIAEs in children who required TI in the pediatric ICU after accounting for site-level clustering, this result may be explained by differences in patient, provider, and practice factors. Trial Registration Trial not registered.

Feasibility and safety of THRIVE in transoral laser microsurgery

OBJECTIVE

Transnasal Humidified Rapid Insufflation Ventilatory Exchange (THRIVE) presents obvious advantage in laryngeal surgery and Transoral Laser Microsurgery (TLM). Airway fire represents a rare complication of TLM and may be the most important limitation in the use of THRIVE. The objective was to evaluate the different operating conditions of the TLM with THRIVE with regard to fire risk.

EXPERIMENT

In this report, we assessed the risk of fire by varying the Fraction of Inspired Oxygen (FiO2), the Laser Energy, and the placement of endolaryngeal surgical and ventilatory equipment in a porcine model for TLM.

RESULTS

Fire, sparks and smoke were reported. No combustion occurred with THRIVE in the absence of an endolaryngeal material. Fire occurred systematically while delivering between 3 and 5 W Carbon dioxide (CO2) Laser direct shot on a dry laryngeal cotton. Conclusion THRIVE-TLM should never be performed using a dry cotton or a plastic endolaryngeal material.

Efficiency of different flows for apneic oxygenation when using high flow nasal oxygen application - a technical simulation

Background

Preoxygenation and application of apneic oxygenation are standard to prevent patients from desaturation e.g. during emergency intubation. The time before desaturation occurs can be prolonged by applying high flow oxygen into the airway. Aim of this study was to scientifically assess the flow that is necessary to avoid nitrogen entering the airway of a manikin model during application of pure oxygen via high flow nasal oxygen.

Methods

We measured oxygen content over a 20-min observation period for each method in a preoxygenated test lung applied to a human manikin, allowing either room air entering the airway in control group, or applying pure oxygen via high flow nasal oxygen at flows of 10, 20, 40, 60 and 80 L/min via nasal cannula in the other groups. Our formal hypothesis was that there would be no difference in oxygen fraction decrease between the groups.

Results

Oxygen content in the test lung dropped from 97 ± 1% at baseline in all groups to 43 ± 1% in the control group (p < 0.001 compared to all other groups), to 92 ± 1% in the 10 L/min group, 92 ± 1% in the 20 L/min group, 90 ± 1% in the 40 L/min group, 89 ± 0% in the 60 L/min group and 87 ± 0% in the 80 L/min group. Apart from comparisons 10 l/ min vs. 20 L/min group (p = .715) and 10/L/min vs. 40 L/min group (p = .018), p was < 0.009 for all other comparisons.

Conclusions

Simulating apneic oxygenation in a preoxygenated manikin connected to a test lung over 20 min by applying high flow nasal oxygen resulted in the highest oxygen content at a flow of 10 L/min; higher flows resulted in slightly decreased oxygen percentages in the test lung.

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.

Apneic laryngeal oxygenation during elective fiberoptic intubation - a technical simulation

Background

Sedation during elective fiberoptic intubation for difficult airway can cause respiratory depression, apnea and periods of desaturation. During apneic episodes, hypoxemia can be prevented by insufflation of oxygen in the deep laryngeal space. The aim of this study was to evaluate an oropharyngeal oxygenation device (OOD) designed for deep laryngeal insufflation during fiberoptic intubation.

Methods

The OOD is split in the front to form a path for the bronchoscope. An external lumen delivers oxygen in the deep laryngeal space. In this experimental study, air application (as control group), oxygen application via nasal prongs, oxygen application via the OOD, and oxygen application via the working channel of a bronchoscope were compared in a technical simulation. In a preoxygenated test lung of a manikin, decrease of the oxygen saturation was measured over 20 min for each method.

Results

Oxygen saturation in the test lung dropped from 97 ± 1% (baseline in all groups) to 58 ± 3% in the control-group (p < 0.001 compared to all other groups) and to 78 ± 1% in the nasal prong group (p < 0.001 compared to all other groups). Oxygen saturation remained at 95 ± 2% in both the OOD group and the bronchoscopy group (p = 0.451 between those two groups).

Conclusion

Simulating apneic laryngeal oxygenation in a preoxygenated manikin, both oxygen insufflation via the OOD and the bronchoscope kept oxygen saturation in the test lung at 95% over 20 min. Both methods significantly were more effective than oxygen insufflation via nasal prongs.

Utility of oxygen insufflation through working channel during fiberoptic intubation in apneic patients: a prospective randomized controlled study

BACKGROUND

Airway management is a part of routine anesthetic procedures; however, serious complications, including hypoxia and death, are known to occur in cases of difficult airways. Therefore, alternative techniques such as fiberoptic bronchoscope-assisted intubation (FOB intubation) should be considered, although this method requires more time and offers a limited visual field than does intubation with a direct laryngoscope. Oxygen insufflation through the working channel during FOB intubation could minimize the risk of desaturation and improve the visual field. Therefore, the aim of this prospective randomized controlled study was to evaluate the utility and safety of oxygen insufflation through the working channel during FOB intubation in apneic patients.

METHODS

Thirty-six patients were randomly allocated to an N group (no oxygen insufflation) or an O group (oxygen insufflation). After preoxygenation, FOB intubation was performed with (O group) or without (N group) oxygen insufflation in apneic patients. The primary outcome was the velocity of decrease in the partial pressure of oxygen (PaO₂) during FOB intubation (V_PaO2, mmHg/sec) defined as the difference of PaO₂ before and after intubation divided by the time to intubation. The secondary outcomes included the success rate for FOB intubation, time to intubation, visual field during FOB intubation, findings of arterial blood gas analysis, and occurrence of FOB intubation-related complications.

RESULTS

We found that V_PaO2 was significantly greater in the N group than in the O group (1.0 ± 0.4 vs. 0.4 ± 0.4; p < 0.001), while the visual field was similar between groups. There were no significant intergroup differences in the secondary outcomes.

CONCLUSIONS

These findings suggest that oxygen insufflation through the working channel during FOB intubation aids in extending the apneic window during the procedure.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT02625194 , registered at December 9, 2015.

Comparison of different methods for lung immobilization in an animal model

BACKGROUND AND PURPOSE

Respiratory-induced motion introduces uncertainties in the delivery of dose in radiotherapy treatments. Various methods are used clinically, e.g. breath-holding, while there is limited experience with other methods such as apneic oxygenation and high frequency jet ventilation (HFJV). This study aims to compare the latter approaches for lung immobilization and their clinical impact on gas exchange in an animal model.

MATERIALS AND METHODS

Two radiopaque tumor surrogate markers (TSM) were placed in the central (cTSM) and peripheral (dTSM) regions of the lungs in 9 anesthetized and muscle relaxed pigs undergoing 3 ventilatory interventions (1) HFJV at rates of 200 (JV200), 300 (JV300) and 400 (JV400) min^-1; (2) apnea at continuous positive airway pressure (CPAP) levels of 0, 8 and 16 cmH₂O; (3) conventional mechanical ventilation (CMV) as reference mode. cTSM and dTSM were visualized using fluoroscopy and their coordinates were computed. The ventilatory pattern was registered, and oxygen and carbon dioxide (pCO₂) partial pressures were measured.

RESULTS

The highest range of TSM motion, and ventilation was found during CMV, the lowest during apnea. During HFJV the amount of motion varied inversely with increasing frequency. The reduction of TSM motion at JV300, JV400 and all CPAP levels came at the cost of increased pCO₂, however the relatively low frequency of 200 min^-1 for HFJV was the only ventilatory setting that enabled adequate CO₂ removal.

CONCLUSION

In this model, HFJV at 200 min^-1 was the best compromise between immobilization and gas exchange for sessions of 10-min duration.

Hyperoxia affects the lung tissue: A porcine histopathological and metabolite study using five hours of apneic oxygenation

Background

Oxygen is a liberally dosed medicine; however, too much oxygen can be harmful. In certain situations, treatment with high oxygen concentration is necessary, e.g. after cardiopulmonary resuscitation. The amount of oxygen and duration of hyperoxia causing pulmonary damage is not fully elucidated. The aim of this study was to investigate pathophysiological and metabolite changes in lung tissue during hyperoxia while the lungs were kept open under constant low pressure.

Methods

Seven pigs were exposed to 100% oxygen for five hours, using an apneic oxygenation technique with one long uninterrupted inspiration, while carbon dioxide was removed with an interventional lung assist. Arterial blood samples were collected every 30 minutes. Lung biopsies were obtained before and after hyperoxia. Microscopy and high-resolution magic angle spinning nuclear magnetic resonance spectroscopy were used to detect possible pathological and metabolite changes, respectively. Unsupervised multivariate analysis of variance and paired sample tests were performed. A two-tailed p-value ≤ 0.05 was considered significant.

Results

No significant changes in arterial pH, and partial pressure of carbon dioxide, and no clear histopathological changes were observed after hyperoxia. While blood glucose and lactate levels changed to a minor degree, their levels dropped significantly in the lung after hyperoxia (p ≤ 0.04). Reduced levels of antioxidants (p ≤ 0.05), tricarboxylic acid cycle and energy (p ≤ 0.04) metabolites and increased levels of several amino acids (p ≤ 0.05) were also detected.

Conclusion

Despite no histological changes, tissue metabolites were altered, indicating that exposure to hyperoxia affects lung tissue matrix on a molecular basis.

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No significant histopathological changes in lung tissue after five hours hyperoxia.

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Five hours hyperoxia induces significant metabolite changes in lung tissue.

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Hyperoxia affects cellular energy, Krebs cycle, and oxidant-antioxidant defense.

Thunberg's Barospirator, a Fully Encasing Predecessor of the Iron Lung

Used as a ventilator for assisting victims of polio, the barospirator was described by Swedish physician-scientist Torsten Thunberg in 1924. An immediate predecessor of the iron lung of Philip Drinker, the barospirator fully encased the entire body. Cyclic air-pressure changes within the chamber achieved ventilation during equilibrations of intrapulmonary and ambient pressures. Pulmonary medicine innovator Alvan Leroy Barach used a modified barospirator for lung rest as a treatment of tuberculosis in the 1940s. Adverse effects included damage to patients' tympanic membranes. Despite its limited clinical success, the barospirator was successfully used by one of Drinker's competitors, John H. Emerson, to invalidate Drinker's US patent filings.

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.

Proton beam therapy in apneic oxygenation treatment of an unresectable hepatocellular carcinoma: A case report and review of literature

Presented here is the clinical course of a 63-year-old patient with a central, large and unresectable hepatocellular carcinoma (HCC) with liver metastases and tumor invasion of the portal and hepatic veins. After the tumor had been diagnosed, the patient was immediately treated with proton beam therapy (PBT), at a total dose of 60 Gy (relative biological effectiveness) in 20 fractions administered within 4 wk. To manage the respiratory movements, at the Rinecker Proton Therapy Center, apneic oxygenation was given daily, under general anesthesia. The patient tolerated both the PBT and general anesthesia very well, and did now show any signs of acute or late toxicity. The treatment was followed by constant reductions in the tumor marker alpha-fetoprotein and the cholestatic parameters gamma-glutamyltransferase and alkaline phosphatase. The patient commenced an adjuvant treatment with sorafenib, given at 6-wk intervals, after the PBT. Follow-up with regular magnetic resonance imaging has continued for 40 mo so far, demonstrating remarkable shrinkage of the HCC (maximal diameter dropping from approximately 13 cm to 2 cm). To date, the patient remains free of tumor recurrence. PBT served as a safe and effective treatment method for an unresectable HCC with vascular invasion.

Effect of nasal or nasopharyngeal apneic oxygenation on desaturation during induction of anesthesia and endotracheal intubation in the operating room: A narrative review of randomized controlled trials

OBJECTIVES

To determine whether apneic oxygenation through nasal or nasopharyngeal catheters can counteract hypoxemia and desaturation during induction of anesthesia and endotracheal intubation.

DESIGN

Narrative review of randomized controlled trials.

SETTING

Operating room.

PATIENTS

295 ASA I-II patients in elective surgery.

INTERVENTION

PubMed and Embase databases were searched for studies with apneic oxygenation. The review included randomized controlled trials with apneic oxygenation through nasal or nasopharyngeal catheters as the intervention in the setting of endotracheal intubation in adults.

MEASUREMENTS

Outcome measures were time until desaturation or degree of hypoxemia.

MAIN RESULTS

Eight randomized controlled trials were included, with a total of 295 patients. Apneic oxygenation was administered by nasopharyngeal catheter in four studies and by nasal catheter in four studies. The eight included articles studied apneic oxygenation at flow rates of 3-10 l/min in ASA I-II patients undergoing elective anesthesia in the operating room. Apneic oxygenation significantly prolonged time until desaturation opposed to the control groups in seven of the eight studies of patients undergoing anesthesia for elective surgery.

CONCLUSION

Apneic oxygenation through nasal or nasopharyngeal catheters can prolong time to desaturation and decrease degree of desaturation during induction of anesthesia and endotracheal intubation in adult ASA I-II patients undergoing anesthesia for elective surgery.

Apneic oxygenation reduces hypoxemia during endotracheal intubation in the pediatric emergency department

BACKGROUND

Apneic oxygenation (AO) has been evaluated in adult patients as a means of reducing hypoxemia during endotracheal intubation (ETI). While less studied in pediatric patients, its practice has been largely adopted.

OBJECTIVE

Determine association between AO and hypoxemia in pediatric patients undergoing ETI.

METHODS

Observational study at an urban, tertiary children's hospital emergency department. Pediatric patients undergoing ETI were examined during eras without (January 2011-June 2011) and with (August 2014-March 2017) apneic oxygenation. The primary outcome was hypoxemia, defined as pulse oximetry (SpO₂) < 90%. The χ² and Wilcoxon rank-sum tests examined differences between cohorts. Multivariable regression models examined adjusted associations between covariates and hypoxemia.

RESULTS

149 patients were included. Cohorts were similar except for greater incidence of altered mental status in those receiving AO (26% vs. 7%, p = 0.03). Nearly 50% of the pre-AO cohort experienced hypoxemia during ETI, versus <25% in the AO cohort. Median [IQR] lowest SpO₂ during ETI was 93 (69, 99) for pre-AO and 100 [95, 100] for the AO cohort (p < 0.001). In a multivariable logistic regression model, hypoxemia during ETI was associated with AO (aOR 0.3, 95% confidence interval [CI] 0.1-0.8), increased age (for 1 year, aOR 0.8, 95% CI 0.7-1.0), lowest SpO₂ before ETI (for 1% increase, aOR 0.9, 95% CI 0.8-1.0), and each additional intubation attempt (aOR 4.0, 95% CI 2.2-7.2).

CONCLUSIONS

Apneic oxygenation is an easily-applied intervention associated with decreases in hypoxemia during pediatric ETI. Nearly 50% of children not receiving AO experienced hypoxemia.

Respiratory support techniques to avoid desaturation in critically ill patients requiring endotracheal intubation: A systematic review and meta-analysis

PURPOSE

To evaluate which respiratory support method for critically ill patients undergoing endotracheal intubation (ETI) is associated with less desaturation.

METHODS

We searched PubMed, Cochrane Library, Scopus and CINAHL databases. We included randomized (RCT) and non-randomized (non-RCT) studies investigating any method of respiratory support before/during ETI compared to a reference control.

RESULTS

Apneic oxygenation (ApOx) was the most commonly investigated respiratory support technique for critically ill patients undergoing intubation (4 RCTs, 358 patients). Three of these studies investigated high-flow nasal cannula (HFNC) for ApOx while standard nasal cannula was used in one. Globally, ApOx was associated with higher minimum SpO₂ value compared to those receiving ETI without ApOx (mean difference 2.31%, 95% CI 0.42 to 4.20, p=0.02, I²=0%) but there were not significant differences between groups in severe hypoxemia and intubation related - complications. Concerning other techniques, noninvasive ventilation (NIV) was compared to bag-valve mask in only one RCT and it reduced the degree of desaturation.

CONCLUSIONS

ApOx was significantly associated with higher minimum SpO₂ registered during the intubation procedure. Further studies are needed to increase the number of included patients and demonstrate the benefit of ApOx and of other respiratory support methods (e.g. NIV, HFNC).

Apneic oxygenation is associated with a reduction in the incidence of hypoxemia during the RSI of patients with intracranial hemorrhage in the emergency department

Critically ill patients undergoing emergent intubation are at risk of oxygen desaturation during the management of their airway. Patients with intracranial hemorrhage (ICH) are particularly susceptible to the detrimental effects of hypoxemia. Apneic oxygenation (AP OX) may be able to reduce the occurrence of oxygen desaturation during the emergent intubation of these patients. We sought to assess the effect AP OX on oxygen desaturation during the rapid sequence intubation (RSI) of patients with ICH in the emergency department (ED). We prospectively collected data on all patients intubated in an urban academic ED over the 2-year period from July 1, 2013 to June 30, 2015. Following each intubation, the operator completed a standardized continuous quality improvement (CQI) data form, which included information on patient, operator and intubation characteristics. Operators recorded data on the use of AP OX, the oxygen flow rate used for AP OX, and the starting and lowest saturations during intubation. Adult patients with ICH who underwent RSI by emergency medicine (EM) residents were included in the analyses. The primary outcome variable was any oxygen saturation <90 % during the intubation. We performed a backward stepwise multivariate logistic regression analysis to identify variables associated with oxygen desaturation. The primary independent variable of interest was the use of AP OX during the intubation. Inclusion criteria for the study was met by 127 patients. AP OX was used in 72 patients (AP OX group) and was not used in 55 patients (NO AP OX group). The incidence of desaturation was 5/72 (7 %) in the AP OX group and was 16/55 (29 %) in the NO AP OX group. In the multivariate logistic regression analysis the use of AP OX was associated with a reduced odds of desaturation (aOR 0.13; 95 % CI 0.03-0.53). Patients with ICH who received AP OX during RSI in the ED were seven times less likely to have an oxygen saturation of <90 % during the intubation compared to patients who did not receive AP OX. AP OX is a simple intervention that may minimize the risk of oxygen desaturation during the RSI of patients with ICH.

Apneic Oxygenation: A Method to Prolong the Period of Safe Apnea

A difficult intubation poses one of the most challenging tasks for anesthesia professionals, representing 27% of all adverse respiratory events, 93% of which are unanticipated. Unanticipated difficult mask ventilation and intubation may result in serious complications. Safe airway management requires a proper and thorough preoperative airway evaluation and a plan to secure the airway, with alternate plans available when the initial plan fails. Pediatric, obese, and obstetric patients undergoing general anesthesia with endotracheal intubation are considered to be at risk of rapid desaturation. As an adjunct to conventional preoxygenation techniques, continuous oxygen administration during the apneic period, termed apneic oxygenation, assists in the maintenance of oxygenation when tracheal intubation is attempted. Nine articles were selected for appraisal in this literature review: 6 randomized control trials, 2 prospective studies, and 1 retrospective study. Multiple apneic oxygenation techniques, including nasopharyngeal catheter, nasal prongs, endotracheal tube, intratracheal catheter, and high-flow transnasal humidified oxygen, demonstrated effectiveness at delaying the onset of hypoxemia during the apnea period. Prolonging the apneic window changes the nature of airway management in patients at high risk of desaturation and when an unanticipated difficult airway arises.

Preoxygenation and apneic oxygenation using Transnasal Humidified Rapid-Insufflation Ventilatory Exchange for emergency intubation

PURPOSE

Hypoxia is one of the leading causes of anesthesia-related injury. In response to the limitations of conventional preoxygenation, Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE) has been used as a method of providing both preoxygenation and apneic oxygenation during intubation.

MATERIALS AND METHODS

In this prospective, observational study, THRIVE was introduced in a critical care unit (CCU), operating room (OR), and emergency department (ED) during emergency intubation of patients at high risk of hypoxia. Linear regression analysis tested for correlation between apnea time or body mass index and hemoglobin saturation (Spo₂).

RESULTS

Across 71 sequential patients, the interquartile range for apnea time and decrease in Spo₂ were 60 to 125 seconds and 0% to 3%, respectively. Significant desaturation occurred in 5 (7%) patients. There was no evidence of correlation between apnea time or body mass index and Spo₂ (R²=0.04 and 0.08 for CCU/ED and OR and 0.01 and 0.04 CCU/ED and OR, respectively). There were no complications reported from using THRIVE.

CONCLUSIONS

This study demonstrated that preoxygenation and apneic oxygenation using THRIVE were associated with a low incidence of desaturation during emergency intubation of patients at high risk of hypoxia in the CCU, OR, and ED. THRIVE has the potential to minimize the risk of hypoxia in these patient groups.

Apneic Oxygenation during simulated prolonged difficult laryngoscopy: Comparison of nasal prongs versus nasopharyngeal catheter: A prospective randomized controlled study

Background:

Apneic oxygenation by insufflating O₂ through nasal prongs (NP) and nasopharyngeal catheter (NC) has been proven to be effective. We conducted this study to compare the relative efficacy of these two techniques in a simulated difficult airway situation.

Objective:

The objective of this study is to evaluate the influence of two techniques of apneic oxygenation (NP vs. NC) on the duration of oxygen saturation ≥95% during simulated prolonged difficult laryngoscopy.

Methods:

A randomized non-blinded study was conducted in 56 adult patients, 28 in each group belonging to American Society of Anesthesiologists physical status class I and II scheduled for elective surgical procedures under general endotracheal anesthesia randomized to either NC or NP group. After pre-oxygenating for an end tidal oxygen concentration of 90% and induction, ability to mask ventilate was checked and paralyzed with rocuronium. Apneic oxygenation using 5 L/min of O₂ was established either by NP or NC. After laryngoscopy the laryngoscope was withdrawn to simulate a Grade 4 laryngoscopy and held in this position for an apnea time (T₁) of 10 min with SpO₂ maintained at ≥95% or until SpO₂ dropped to < 95%, whichever is earlier. An arterial blood gas analysis was performed at the end of T₁. Desaturation to < 95% were compared between the groups using Chi-square test (P < 0.05 as significant). Arterial blood gas analysis among those who sustained T₁ for 10 min between the groups were compared using independent sample t-test (P < 0.05 was considered as significant). None of patients were excluded from the study.

Results:

In NP group nine patients desaturated as against none in the NC group (P = 0.001). Arterial blood gas analysis among non-desaturated patients was comparable with respect to PO₂, PCO₂ and pH.

Conclusion:

Nasopharyngeal catheter is a better device than nasal prongs in maintaining safe oxygenation during apnea in a simulated prolonged difficult laryngoscopy.