Prospective Evaluation of a Modified Apnea Test in Brain Death Candidates that Does Not Require Disconnection from the Ventilator.

BACKGROUND: The apnea test (AT) is an important component in the determination of brain death/death by neurologic criteria (BD/DNC) and often entails disconnecting the patient from the ventilator followed by tracheal oxygen insufflation to ensure adequate oxygenation. To rate the test as positive, most international guidelines state that a lack of spontaneous breathing must be demonstrated when the arterial partial pressure of carbon dioxide (PaCO2) ≥ 60 mm Hg. However, the loss of positive end-expiratory pressure that is associated with disconnection from the ventilator may cause rapid desaturation. This, in turn, can lead to cardiopulmonary instability (especially in patients with pulmonary impairment and diseases such as acute respiratory distress syndrome), putting patients at increased risk. Therefore, this prospective study aimed to investigate whether a modified version of the AT (mAT), in which the patient remains connected to the ventilator, is a safer yet still valid alternative. METHODS: The mAT was performed in all 140 BD/DNC candidates registered between January 2019 and December 2022: after 10 min of preoxygenation, (1) positive end-expiratory pressure was increased by 2 mbar (1.5 mm Hg), (2) ventilation mode was switched to continuous positive airway pressure, and (3) apnea back-up mode was turned off (flow trigger 10 L/min). The mAT was considered positive when spontaneous breathing did not occur upon PaCO2 increase to ≥ 60 mm Hg (baseline 35-45 mm Hg). Clinical complications during/after mAT were documented. RESULTS: The mAT was possible in 139/140 patients and had a median duration of 15 min (interquartile range 13-19 min). Severe complications were not evident. In 51 patients, the post-mAT arterial partial pressure of oxygen (PaO2) was lower than the pre-mAT PaO2, whereas it was the same or higher in 88 cases. In patients with pulmonary impairment, apneic oxygenation during the mAT improved PaO2. In 123 cases, there was a transient drop in blood pressure at the end of or after the mAT, whereas in 12 cases, the mean arterial pressure dropped below 60 mm Hg. CONCLUSIONS: The mAT is a safe and protective means of identifying patients who no longer have an intact central respiratory drive, which is a critical factor in the diagnosis of BD/DNC. Clinical trial registration DRKS, DRKS00017803, retrospectively registered 23.11.2020, https://drks.de/search/de/trial/DRKS00017803.

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.

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).

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.

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

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

High-flow nasal cannula in nonlaser microlaryngoscopic surgery: a prospective study of 19 cases in a chinese population.

BACKGROUND: High-flow nasal cannula (HFNC) is a new type of oxygen therapy, but its application in surgery remains unclear, we tried to describe the application of HFNC in microlaryngoscopic surgery for the Chinese population. METHODS: Nineteen adults, American society of anesthesiology class (ASA) 1-2 patients with body mass index < 30 kg.m-2 underwent microlaryngoscopic surgery using HFNC for airway management. Outcomes included apnoea time, intraoperative oxygenation, carbon dioxide value, lactate value, and the relationship between the duration of apnoea time and carbon dioxide levels. RESULTS: A total of 19 patients underwent vocal cord tumor resection under a microlaryngoscope with HFNC as the sole method of ventilation. The mean age was 39.7 years old, and the mean BMI was 23.9 kg.m-2. The mean apnea time was 21.5 min. The SpO2 of 18 patients remained above 90%, and only 1 patient dropped to 88%. The average basal lactate and highest lactate value was 0.58 mmol. L-1 and 0.68 mmol.L-1. The difference between basal and highest lactate values was statistically significant (P < 0.05). The average highest PaCO2 value was 79.4 mmHg. The PaCO2 increased by 1.68 ± 0.12 mmHg every minute linearly. CONCLUSIONS: In the case series we have observed that HFNC would be safe and effective oxygenation and ventilation technique for selected Chinese patients undergoing non-laser microlaryngoscopic surgery within 30 min. The tubeless technology reduces the complications of tracheal intubation and jet ventilation and clears the surgical field of vision. TRIAL REGISTRATION: Chinese Clinical Trial Registry ( ChiCTR100049144 ).

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.

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 (VPaO2, 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 VPaO2 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.

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.

Normal and difficult airways in children: "What's New"-Current evidence.

BACKGROUND: Pediatric difficult airway is one of the most challenging clinical situations. We will review new concepts and evidence in pediatric normal and difficult airway management in the operating room, intensive care unit, Emergency Department, and neonatal intensive care unit. METHODS: Expert review of the recent literature. RESULTS: Cognitive factors, teamwork, and communication play a major role in managing pediatric difficult airway. Earlier studies evaluated videolaryngoscopes in a monolithic way yielding inconclusive results regarding their effectiveness. There are, however, substantial differences among videolaryngoscopes particularly angulated vs. nonangulated blades which have different learning and use characteristics. Each airway device has strengths and weaknesses, and combining these devices to leverage both strengths will likely yield success. In the pediatric intensive care unit, emergency department and neonatal intensive care units, adverse tracheal intubation-associated events and hypoxemia are commonly reported. Specific patient, clinician, and practice factors are associated with these occurrences. In both the operating room and other clinical areas, use of passive oxygenation will provide additional laryngoscopy time. The use of neuromuscular blockade was thought to be contraindicated in difficult airway patients. Newer evidence from observational studies showed that controlled ventilation with or without neuromuscular blockade is associated with fewer adverse events in the operating room. Similarly, a multicenter neonatal intensive care unit study showed fewer adverse events in infants who received neuromuscular blockade. Neuromuscular blockade should be avoided in patients with mucopolysaccharidosis, head and neck radiation, airway masses, and external airway compression for anticipated worsening airway collapse with neuromuscular blocker administration. CONCLUSION: Clinicians caring for children with difficult airways should consider new cognitive paradigms and concepts, leverage the strengths of multiple devices, and consider the role of alternate anesthetic approaches such as controlled ventilation and use of neuromuscular blocking drugs in select situations. Anesthesiologists can partner with intensive care and emergency department and neonatology clinicians to improve the safety of airway management in all clinical settings.

A review of the use of transnasal humidified rapid insufflation ventilatory exchange for patients undergoing surgery in the shared airway setting.

Transnasal humidified rapid insufflation ventilatory exchange (THRIVE) is a recent technique that delivers warm humidified high flow oxygen to patients, allowing for prolonged apneic oxygenation. A review of current literature was performed to determine the use of THRIVE in apneic patients undergoing surgery in a shared airway setting. An initial free hand search was done to identify keywords followed by a systematic search of major databases with no date or language restrictions. Inclusion criteria include all apneic patients who receive THRIVE for any operative procedure. Fifteen studies fulfilled the inclusion criteria. There were ten case series, two case reports, two review articles and one randomized controlled trial. All of the studies discussed the use of THRIVE during laryngopharyngeal surgeries. The median apnea time reported ranged between 13 and 27 min. There were no significant complications reported as a result of using THRIVE. Most studies identified in this review were observational in nature involving laryngopharyngeal procedures. They have demonstrated THRIVE to be effective in providing apneic oxygenation during short procedures in adult patients. Further studies are required to determine the limitations of safe use in specific populations and when THRIVE is combined with diathermy or laser use.

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.

Apneic oxygenation to prevent oxyhemoglobin desaturation during rapid sequence intubation in a pediatric emergency department.

BACKGROUND: Apneic oxygenation is the delivery of oxygen to the nasopharynx during intubation. It may mitigate the risk of oxyhemoglobin desaturation but has not been well-studied in children. METHODS: We conducted a retrospective, observational study of patients undergoing rapid sequence intubation (RSI) in a pediatric emergency department. We compared patients who received apneic oxygenation, delivered via simple nasal cannula at age-specific flow rates, to patients who did not receive apneic oxygenation. The main outcome was occurrence of oxyhemoglobin desaturation during RSI, defined as oxyhemoglobin saturation dropping to <90% at any time after the administration of paralytic medication and before the endotracheal tube was secured. Data were analyzed using logistic regression, with groups as a fixed effect and patients' age and number of attempts as covariates. RESULTS: Data were collected for 305 of 323 patients who underwent RSI over a 49 month period. Oxyhemoglobin desaturation occurred for 50 patients when apneic oxygenation was used (22%, 95% CI 17% to 28%) and 11 patients without apneic oxygenation (14%, 95% CI 7% to 24%; p > 0.05). There was no difference in the median duration of desaturation or depth of desaturation for the apneic oxygenation group (52 s, 71%) compared to the group without apneic oxygenation (65 s, 79%; p > 0.05). Controlling for covariates, apneic oxygenation was not associated with a lower risk of oxyhemoglobin desaturation, time to desaturation, or depth/duration of desaturation episodes. CONCLUSIONS: In an observational, video-based study of pediatric patients, apneic oxygenation was not associated with a lower risk of oxyhemoglobin desaturation during RSI.

End-Tidal Oxygen Saturation with Nasal Cannula During Noninvasive Positive Pressure Ventilation: A Randomized Crossover Trial.

BACKGROUND: Simultaneous use of nasal cannula (NC) with noninvasive positive pressure ventilation (NIPPV) may help streamline the transition from preoxygenation to intubation with apneic oxygenation in patients with deteriorating respiratory status, but may also compromise preoxygenation by impairing NIPPV mask seal. OBJECTIVES: To demonstrate that end-tidal oxygen (EtO2) after NIPPV with NC is noninferior to that of NIPPV without NC. METHODS: We conducted a randomized cross-over noninferiority study using healthy volunteers. All subjects underwent a 3-min trial of NIPPV with or without high-flow NC at 15 L/min of oxygen, followed by a 5-min washout period, and then a second 3-min trial of the opposite intervention. We randomized subjects to order of interventions. The primary outcome was postintervention EtO2 as measured by immediate exhalation into an oxygen analyzer after the 3-min ventilation period. We compared this outcome between the two study arms using an absolute 5% noninferiority margin. RESULTS: We enrolled 37 subjects, each of whom underwent both interventions of NIPPV alone and NIPPV with 15 L/min NC. The paired mean difference in EtO2 between NIPPV with NC measurements vs. NC alone measurements was 0.5% (95% confidence interval -∞ to 2.7%). Analyses stratified by order of intervention yielded similar results. CONCLUSIONS: The mean difference confidence interval did not include the noninferiority margin. Hence, NIPPV with NC seems noninferior to NIPPV alone with regard to EtO2. These results indicate that concomitant use of NC with NIPPV may be an appropriate preoxygenation strategy in anticipation of the potential need for transition to intubation.

Apneic oxygenation reduces the incidence of hypoxemia during emergency intubation: A systematic review and meta-analysis.

STUDY OBJECTIVE: Apneic oxygenation has been advocated for the prevention of hypoxemia during emergency endotracheal intubation. Because of conflicting results from recent trials, the efficacy of apneic oxygenation remains unclear. We performed a systematic review and meta-analysis to investigate the effect of apneic oxygenation on the incidence of clinically significant hypoxemia during emergency endotracheal intubation. METHODS: MEDLINE, EMBASE, and PubMed databases were searched without language and time restrictions for studies of apneic oxygenation performed in a critical care setting. Meta-analysis was conducted with a random-effect model, and according to intention-to-treat allocation wherever applicable. Subgroup analyses were performed to ensure the robustness of findings across various clinical outcomes. RESULTS: Eight studies (n=1953) were included in the meta-analysis. The pooled absolute risk of clinically significant hypoxemia was 27.6% in the usual care group and 19.1% in the apneic oxygenation group, without any heterogeneity across studies (I2=0%; p=0.42). Apneic oxygenation reduced the relative risk of hypoxemia by 30% (95% confidence interval 0.59 to 0.82). There was a trend toward lower mortality in the apneic oxygenation group (relative risk of death 0.77; 95% confidence interval 0.59 to 1.02). CONCLUSION: Apneic oxygenation significantly reduces the incidence of hypoxemia during emergency endotracheal intubation. These findings support the inclusion of apneic oxygenation in everyday clinical practice.

Apneic Oxygenation Versus Low-Tidal-Volume Ventilation in Anesthetized Cardiac Surgical Patients: A Prospective, Single-Center, Randomized Controlled Trial.

OBJECTIVES: To compare the physiology of apneic oxygenation with low-tidal-volume (VT) ventilation during harvesting of the left internal mammary artery. DESIGN: Prospective, single-center, randomized trial. SETTING: Single-center teaching hospital. PARTICIPANTS: The study comprised 24 patients who underwent elective coronary artery bypass grafting surgery. INTERVENTIONS: Apneic oxygenation (apneic group: 12 participants) and low-VT ventilation (low-VT group: 12 participants) (2.5 mL/kg ideal body weight) for 15 minutes during harvesting of the left internal mammary artery. MEASUREMENT AND MAIN RESULTS: The primary endpoint was an absolute change in partial pressure of arterial carbon dioxide (PaCO2). Secondary endpoints were changes in arterial pH, pulmonary artery pressures (PAP), cardiac index, and pulmonary artery acceleration time and ease of surgical access. The mean (standard deviation) absolute increase in PaCO2 was 31.8 mmHg (7.6) in the apneic group and 17.6 mmHg (8.2) in the low-VT group (baseline-adjusted difference 14.2 mmHg [95% confidence interval 21.0-7.3], p<0.001). The mean (standard deviation) absolute decrease in pH was 0.15 (0.03) in the apneic group and 0.09 (0.03) in the low-VT group baseline-adjusted difference 0.06 [95% confidence interval 0.03-0.09], p<0.001. Differences in the rate of change over time between groups (time-by-treatment interaction) were observed for PaCO2 (p<0.001), pH (p<0.001), systolic PAP (p = 0.002), diastolic PAP (p = 0.023), and mean PAP (p = 0.034). Both techniques provided adequate ease of surgical access; however, apneic oxygenation was preferred predominantly. CONCLUSIONS: Apneic oxygenation caused a greater degree of hypercarbia and respiratory acidemia compared with low-VT ventilation. Neither technique had deleterious effects on PAP or cardiac function. Both techniques provided adequate ease of surgical access.

A dual-use laryngoscope to facilitate apneic oxygenation.

BACKGROUND: In preoxygenated patients, time until oxygen saturation drops can be extended by insufflating oxygen into their airways, thus oxygenating them apneically. OBJECTIVES: To compare different methods of apneic oxygenation. METHODS: A noncommercial dual-use laryngoscope with an internal lumen in its blade was used to provide oxygen insufflation into a simulated laryngeal space during intubation. In this experimental study, oxygen insufflation via the dual-use laryngoscope was compared with no oxygen insufflation, with nasal oxygen insufflation, and with direct intratracheal oxygen insufflation. In a preoxygenated test lung of a manikin, oxygen percentage decrease was measured over a 20-min observation period for each method of oxygen application. RESULTS: Oxygen percentage in the test lung dropped from 97% to 37 ± 1% in the control group (p < 0.001 compared to all other groups) and to 68 ± 1% in the nasal insufflation group (p < 0.001 compared to all other groups). Oxygen percentage remained over 90% in both the direct intratracheal insufflation group (96 ± 0%) and the laryngoscope blade insufflation group (94 ± 1%) (p < 0.01 between the latter two groups). CONCLUSIONS: Simulating apneic oxygenation in a preoxygenated manikin, deep laryngeal oxygen insufflation via the dual-use laryngoscope kept oxygen percentage in the test lung above 90%, and was more effective than oxygen insufflation via nasal prongs.

Prevention of Oxygen Desaturation in a Patient With Previous Experience of Severe Hypoxia in Modified Electroconvulsive Therapy by Transnasal Humidified Rapid-Insufflation Ventilator Exchange: A Case Report.

Transnasal humidified rapid-insufflation ventilator exchange (THRIVE) has been reported to have better efficacy during anesthesia induction compared to conventional mask ventilation, including improved oxygenation and prolonged safe apnea time. This study reports on the effectiveness of the THRIVE system during modified electroconvulsive therapy (mECT) for a patient experiencing severe hypoxia. A 78-year-old female patient with bipolar disorder received maintenance mECT every four weeks. She previously experienced a significant hypoxic event, with oxygen saturation (SpO2) dropping to 50% following electrical stimulation. In response, we employed the THRIVE system, designed to deliver high-flow, 100% oxygen, thereby extending apnea tolerance. The implementation of THRIVE ensured a stable oxygen supply, maintaining oxygen saturation levels above 95% throughout the mECT procedure. THRIVE is useful for treating hypoxia that occurs due to the unavoidable lack of ventilation during mECT.