The effectiveness of apneic oxygenation during tracheal intubation in various clinical settings: a narrative review

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.

Arterial oxygen pressure during veno-venous extracorporeal membrane oxygenation may be increased by advancing the tip of the drainage cannula into the superior vena cava: a case report

A simple and robust method for veno-venous extracorporeal membrane oxygenation (V-V ECMO) involves a drainage cannula into the inferior vena cava via the femoral vein (FV) and a reinfusion cannula into the right atrium (RA) via the internal jugular vein (IJV) (F-J configuration). However, with this method, the arterial oxygen (PaO2) is said to remain below 100 mmHg.Since recently, in our ICU, to prevent drainage failure, we apply a modification from the commonly practiced F-J configuration by advancing the tip of the drainage cannula inserted via the FV into the superior vena cava (SVC) and crossing the reinfusion cannula inserted via the IJV in the RA (F(SVC)-J(RA) configuration). We experienced that this modification can be associated with unexpectedly high PaO2 values, which here we investigated in detail.Veno-arteriovenous ECMO was induced in a 65-year-old male patient who suffered from repeated cardiac arrest due to acute respiratory distress syndrome. His chest X-ray images showed white-out after lung rest setting, consistent with near-absence of self-lung ventilation. Cardiac function recovered and the system was converted to F(SVC)-J(RA) configuration, after which both PaO2 and partial pressure of pulmonary arterial oxygen values remained high above 200 mmHg. Transesophageal echocardiography could not detect right-to-left shunt, and more efficient drainage of the native venous return flow compared to common F-J configuration may explain the increased PaO2.Although the F(SVC)-J(RA) configuration is a small modification of the F-J configuration, it seems to provide a revolutionary improvement in the ECMO field by combining robustness/simplicity with high PaO2 values.

Spanish Society of Anesthesiology, Reanimation and Pain Therapy (SEDAR), Spanish Society of Emergency and Emergency Medicine (SEMES) and Spanish Society of Otolaryngology, Head and Neck Surgery (SEORL-CCC) Guideline for difficult airway management. Part I

The Airway Management section of the Spanish Society of Anesthesiology, Resuscitation, and Pain Therapy (SEDAR), the Spanish Society of Emergency Medicine (SEMES), and the Spanish Society of Otorhinolaryngology and Head and Neck Surgery (SEORL-CCC) present the Guide for the comprehensive management of difficult airway in adult patients. Its principles are focused on the human factors, cognitive processes for decision-making in critical situations, and optimization in the progression of strategies application to preserve adequate alveolar oxygenation in order to enhance safety and the quality of care. The document provides evidence-based recommendations, theoretical-educational tools, and implementation tools, mainly cognitive aids, applicable to airway management in the fields of anesthesiology, critical care, emergencies, and prehospital medicine. For this purpose, an extensive literature search was conducted following PRISMA-R guidelines and was analyzed using the GRADE methodology. Recommendations were formulated according to the GRADE methodology. Recommendations for sections with low-quality evidence were based on expert opinion through consensus reached via a Delphi questionnaire.

Apnea management during WATCHMAN device deployment with apneic oxygenation: A case report of three cases

WATCHMAN is a percutaneous left atrial appendage closure device that is implanted in patients who are unsuitable for anticoagulation therapy for atrial fibrillation. During WATCHMAN implantation, inducing apnea in the patient is preferable to allow stable deployment. We present three cases in which apneic oxygenation was employed to maintain oxygenation during apnea, and oxygen reserve index (ORiTM) was measured to evaluate its safety and efficacy. Oxygen was administered continuously via the endotracheal tube during apnea. During all four apneic events in three patients (mean duration of 356 seconds), the ORi values maintained above 0.24, which is generally considered the threshold of partial pressure of arterial oxygen (PaO2) > 100 mmHg. Transcutaneous oxygen saturation and PaO2 remained above 99% and 300 mmHg, respectively. There were no respiratory or circulatory complications during or after the surgery.

A Literature Review on the Anesthetic Management of Pulmonary Arterial Hypertension in Non-cardiothoracic Surgery

Pulmonary hypertension (PH) is characterized by narrowing small pulmonary arteries, escalating pulmonary vascular resistance, and affecting the entire cardiovascular system. Pulmonary arterial hypertension (PAH) represents a subgroup of PH and typically affects one in 20,000 individuals. When treating individuals with PAH for non-cardiothoracic surgery, anesthetic management strategies should be tailored to the individual's specific needs. This literature review assessed the anesthetic management of PAH in non-cardiothoracic surgery. Electronic databases such as PubMed, ScienceDirect, Ovid Medical Literature Analysis and Retrieval System Online (MEDLINE), Cochrane, and Google Scholar were searched using relevant keywords related to PAH, noncardiac surgery, and anesthesia. Reference lists and author names were also investigated. The articles that met the inclusion criteria provided evidence suggesting that preoperative assessment should be comprehensive, hemodynamic goals should be established, anesthesia providers should be familiar with the underlying pathology, and cross-consultations between surgeons and anesthesia providers are essential for achieving satisfactory outcomes. Furthermore, patient care should extend beyond the surgical procedure into postoperative recovery in the post-anesthesia care unit (PACU) or intensive care unit (ICU) setting. In conclusion, it is vital for anesthetic management strategies to accommodate the unique needs of PAH patients to optimize their safety during perioperative care.

Improvement in vocal-cord visualization with Trachway video intubating stylet using direct oxygen flow and effective analysis of the fraction of inspired oxygen: a bench study

The Trachway video intubating stylet device facilitates the visualization of the airways of patients from the tip of an endotracheal tube (ETT) during intubation. The major limitations of Trachway are the restricted view due to secretions and the risk of a prolonged apnea during intubation. We conducted a bench study to verify the performance of an alternative, easily applicable airway device that allows better visualization of trackways during Trachway-assisted intubation and prevents the detrimental effects of apnea-related hypoxia. We conducted a bench study to thoroughly evaluate the oral-secretion-elimination ability of a newly designed oxygen delivery device (ODD) to improve vocal-cord visualization using the three commonly used ETT sizes (i.e., 7, 7.5, and 8 mm). Moreover, we measured the fraction of inspired oxygen (FiO2) under different, continuous oxygen-flow supplies (1-10 L/min) during intubation. Each condition was analyzed for a 2 min video-stylet-intubation period. The supplemental oxygen flow and FiO2 fraction achieved using our ODD were higher, and smaller ETTs exhibited better secretion elimination. The ODD, which can be easily coupled with Trachway stylets, enabled high-quality visualization during oxygen flows of 6-8 L/min, and higher FiO2 fractions were achieved at higher oxygen flow rates. The use of the ODD improved the visualization of the airways during video stylet-assisted intubations using the additional FiO2 supply. The ODD developed in this study improves the visualization of airways with Trachway stylets and enhances the safety of intubation.

Role of modified nasopharyngeal oxygen therapy in apnoeic oxygenation under general anaesthesia: a single-centre, randomized controlled clinical study

Apnoeic oxygenation is not only important for patients who cannot be intubated/ventilated, but also can be routinely employed when planning to secure the airway.We aimed to compare safe apnoea times between patients receiving modified nasopharyngeal oxygen therapy and those receiving high-flow nasal oxygen therapy (HFNO) following the induction of general anaesthesia.This was a single-centre, randomized controlled clinical study. Eighty-four female patients undergoing elective laparoscopic gynaecological surgery under general anaesthesia were randomly assigned to the high-flow nasal oxygen therapy group (Group HFNO) or the modified nasopharyngeal oxygen therapy group (Group Naso). A Kaplan-Meier survival curve was used to describe the apnoeic oxygenation time.The safe apnoea time of the patients in the Group Naso was higher than that of the patients in the Group HFNO (20 (19.3 to 20.0) vs. 16.5 (12.9 to 20) minutes, P < 0.05). The incidence of SpO₂ < 95% in the Group Naso was lower than that in the Group HFNO; hazard ratio 0.3 (95% confidence interval 0.2 to 0.6, P < 0.0001). Modified nasopharyngeal oxygen therapy which uses far less oxygen than HFNO is a convenient and effective method of apnoeic oxygenation in normal female patients.Trial registration: https://www.chictr.org.cn , ChiCTR2000039433; date of registration: 28/10/2020.

Preoxygenation: from hardcore physiology to the operating room

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

[Is pre-oxygenation with high-flow nasal oxygen safe? randomized control trial of 56 cases of elderly patients during induction of general anesthesia with endotracheal intubation]

OBJECTIVE

To evaluate the safety of preoxygenation with high-flow nasal oxygenation in elderly patients during induction of general anesthesia with endotracheal intubation.

METHODS

Fifty-six elderly patients without difficult airway were randomized equally into high-flow nasal oxygen group (HF group) and conventional mask oxygen group (M group). Preoxygenation was performed for 5 min before induction of general anesthesia and endotracheal intubation. Oxygenation was maintained during laryngoscopy in HF group, and ventilation lasted until laryngoscopy in M group. For all the patients, the general data, cross-sectional area (CSA) of the gastric antrum measured by ultrasonography, arterial partial pressure of oxygen (PaO₂), arterial partial pressure of carbon dioxide (PaCO₂) and arterial oxygen saturation (cSO₂) were recorded before preoxygenation (T1), at 5 min of preoxygenation (T2) and immediately after intubation (T3). The safety time of asphyxia, intubation time, times of mask ventilation and postoperative complications were compared between the two groups.

RESULTS

The general data were comparable between the two groups. After 5 min of preoxygenation, PaO₂ and cSO₂ were significantly increased in both groups, and PaO₂ was significantly higher in HF group than in M group (F=118.108 vs 9.511, P < 0.05). Both PaO₂ and cSO₂ decreased after intubation, but PaO₂ decreased more slowly in HF group and still remained higher than that at T1; cSO₂ decreased significantly in M group to a lower level than that at T1. Compared with those in M group, the patients in HF group showed a significantly longer safety time of asphyxia (t=5.305, P < 0.05) with fewer times of mask ventilation (χ²= 6.720, P < 0.05). PaCO₂ increased after intubation in both groups but was comparable between the two groups (F=3.138, P > 0.05).

CONCLUSION

High-flow nasal oxygen is safe, simple and effective for pre-oxygenation, which, as compared with the conventional oxygen mask, improves arterial oxygen partial pressure and prolongs the safety time of asphyxia to ensure the safety of airway management during induction of general anesthesia in elderly patients with endotracheal intubation.

Comparison of the effectiveness of high-flow nasal oxygen vs. standard facemask oxygenation for pre- and apneic oxygenation during anesthesia induction: a systematic review and meta-analysis

BACKGROUND

In recent years, high flow nasal oxygen (HFNO) has been widely used in clinic, especially in perioperative period. Many studies have discussed the role of HFNO in pre- and apneic oxygenation, but their results are controversial. Our study aimed to examine the effectiveness of HFNO in pre- and apneic oxygenation by a meta-analysis of RCTs.

METHODS

EMBASE, PUBMED, and COCHRANE LIBRARY databases were searched from inception to July 2021 for relevant randomized controlled trails (RCTs) on the effectiveness of HFNO versus standard facemask ventilation (FMV) in pre- and apenic oxygenation. Studies involving one of the following six indicators: (1) Arterial oxygen partial pressure (PaO2), (2) End expiratory oxygen concentration (EtO2), (3) Safe apnoea time, (4) Minimum pulse oxygen saturation (SpO2min), (5) Oxygenation (O2) desaturation, (6) End expiratory carbon dioxide (EtCO2) or Arterial carbon dioxide partial pressure(PaCO2) were included. Due to the source of clinical heterogeneity in the observed indicators in this study, we adopt random-effects model for analysis, and express it as the mean difference (MD) or risk ratio (RR) with a confidence interval of 95% (95%CI). We conducted a risk assessment of bias for eligible studies and assessed the overall quality of evidence for each outcome.

RESULTS

Fourteen RCTs and 1012 participants were finally included. We found the PaO2 was higher in HFNO group than FMV group with a MD (95% CI) of 57.38 mmHg (25.65 to 89.10; p = 0.0004) after preoxygenation and the safe apnoea time was significantly longer with a MD (95% CI) of 86.93 s (44.35 to 129.51; p < 0.0001) during anesthesia induction. There were no significant statistical difference in the minimum SpO2, CO2 accumulation, EtO2 and O2 desaturation rate during anesthesia induction between the two groups.

CONCLUSIONS

This systematic review and meta-analysis suggests that HFNO should be considered as an oxygenation tool for patients during anesthesia induction. Compared with FMV, continuous use of HFNO during anesthesia induction can significantly improve oxygenation and prolong safe apnoea time in surgical patients.

Patients with sleep-disordered breathing for bariatric surgery

The prevalence of patients with obesity continues to rise worldwide and has reached epidemic proportions. There is a strong correlation between obesity and sleep-disordered breathing (SDB), and, in particular, obstructive sleep apnea (OSA). OSA is often undiagnosed in the surgical population. Bariatric surgery has been recognized as an effective treatment option for both obesity and OSA. Laparoscopic bariatric procedures, particularly laparoscopic sleeve gastrectomy (LSG), have become the most frequently performed procedures. OSA has been identified as an independent risk factor for perioperative complications and failure to recognize and prepare for patients with OSA is a major cause of postoperative adverse events, suggesting that all patients undergoing bariatric surgery should be screened preoperatively for OSA. These patients should be treated with an opioid-sparing analgesic plan and continuous positive airway pressure (CPAP) perioperatively to minimize respiratory complications. With the number of bariatric surgical patients with SDB likely to continue rising, it is critical to understand the best practices to manage this patient population.

Tubeless Anesthesia in Subglottic Stenosis: Comparative Review of Apneic Low-Flow Oxygenation With THRIVE

OBJECTIVE

Managing the shared airway in subglottic stenosis presents a unique challenge. Tubeless anesthesia with apneic oxygenation is increasingly being adopted as it overcomes the limitations of access to and visualization of the narrowed subglottis. Low-flow oxygenation (LFO) and transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) are two delivery techniques. We sought to compare their utility in this patient cohort.

STUDY DESIGN

Retrospective cohort study.

METHODS

Thirty-five cases of endoscopic debridement of subglottic stenosis were retrospectively studied. Operative technique was consistent among the cases. Oxygen was delivered at low-flow rates at the laryngeal inlet with LFO (n = 23) or high-flow rates at the nares with THRIVE (n = 12). Data regarding apnea time, the need for rescue ventilation, and relevant patient and disease factors were recorded for analysis.

RESULTS

Median apnea time for LFO and THRIVE were 34 and 25 minutes, respectively. Rescue with intermittent supraglottic jet ventilation was required more often with LFO than THRIVE (61% vs 33%) and was sufficient for the case to be completed in all but one instance. Elevated BMI was the sole significant predictor of early oxygen desaturation (24.8 vs 37.95 kg/m² , P = .002) with LFO. Median stenosis diameter was 6 mm (range 2-14).

CONCLUSION

Apneic techniques are safe and feasible for the endoscopic management of subglottic stenosis of all severities. Elevated BMI is the only significant predictor for early oxygen desaturation. In the many healthcare settings where THRIVE is not available, LFO is a valid alterative in the nonobese patient. Laryngoscope, 2021.

Difficult Airway Management in Adult COVID-19 Patients: Statement by the Society of Airway Management

The COVID-19 disease, caused by Coronavirus SARS-CoV-2, often results in severe hypoxemia requiring airway management. Because SARS CoV-2 virus is spread via respiratory droplets, bag-mask ventilation, intubation, and extubation may place health care workers (HCW) at risk. While existing recommendations address airway management in patients with COVID-19, no guidance exists specifically for difficult airway management. Some strategies normally recommended for difficult airway management may not be ideal in the setting of COVID-19 infection. To address this issue the Society for Airway Management (SAM) created a task force to review existing literature and current Practice Guidelines for management of the difficult airway by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. SAM task force created recommendations for management of known or suspected difficult airway in the setting of known or suspected COVID-19 infection. The goal of the task force was to optimize successful airway management while minimizing exposure risk. Each member conducted a literature review on specific clinical practice section utilizing standard search engines (PubMed, Ovid, Google Scholar). Existing recommendations and evidence for difficult airway management in COVID-19 context were developed. Each specific recommendation was discussed among task force members and modified until unanimously approved by all task force members. Elements of AGREE Reporting Checklist for dissemination of clinical practice guidelines were utilized to develop this statement. Airway management in the COVID-19 patient increases HCW exposure risk. and difficult airway management often takes longer, may involve multiple procedures with aerosolization potential, strict adherence to personal protective equipment (PPE) protocols is mandatory to reduce risk to providers. When patient's airway risk assessment suggests awake tracheal intubation is an appropriate choice of technique, procedures that may cause increased aerosolization of secretions should be avoided. Optimal preoxygenation before induction with tight seal facemask may be performed to reduce risk of hypoxemia. Unless the patient is experiencing oxygen desaturation, positive pressure bag-mask ventilation after induction may be avoided to reduce aerosolization. For optimal intubating conditions, patients should be anesthetized with full muscle relaxation. Videolaryngoscopy is recommended as first-line strategy for airway management. If emergent invasive airway access is indicated, we recommend a surgical technique such as scalpel-bougie-tube, rather than an aerosolizing generating procedure, such as transtracheal jet ventilation. This statement represents recommendations by SAM task force for the difficult airway management of adults with COVID-19 with the goal to optimize successful airway management while minimizing the risk of clinician exposure.

Canadian Airway Focus Group updated consensus-based recommendations for management of the difficult airway: part 2. Planning and implementing safe management of the patient with an anticipated difficult airway

PURPOSE

Since the last Canadian Airway Focus Group (CAFG) guidelines were published in 2013, the published airway management literature has expanded substantially. The CAFG therefore re-convened to examine this literature and update practice recommendations. This second of two articles addresses airway evaluation, decision-making, and safe implementation of an airway management strategy when difficulty is anticipated.

SOURCE

Canadian Airway Focus Group members, including anesthesia, emergency medicine, and critical care physicians were assigned topics to search. Searches were run in the Medline, EMBASE, Cochrane Central Register of Controlled Trials, and CINAHL databases. Results were presented to the group and discussed during video conferences every two weeks from April 2018 to July 2020. These CAFG recommendations are based on the best available published evidence. Where high-quality evidence is lacking, statements are based on group consensus.

FINDINGS AND KEY RECOMMENDATIONS

Prior to airway management, a documented strategy should be formulated for every patient, based on airway evaluation. Bedside examination should seek predictors of difficulty with face-mask ventilation (FMV), tracheal intubation using video- or direct laryngoscopy (VL or DL), supraglottic airway use, as well as emergency front of neck airway access. Patient physiology and contextual issues should also be assessed. Predicted difficulty should prompt careful decision-making on how most safely to proceed with airway management. Awake tracheal intubation may provide an extra margin of safety when impossible VL or DL is predicted, when difficulty is predicted with more than one mode of airway management (e.g., tracheal intubation and FMV), or when predicted difficulty coincides with significant physiologic or contextual issues. If managing the patient after the induction of general anesthesia despite predicted difficulty, team briefing should include triggers for moving from one technique to the next, expert assistance should be sourced, and required equipment should be present. Unanticipated difficulty with airway management can always occur, so the airway manager should have a strategy for difficulty occurring in every patient, and the institution must make difficult airway equipment readily available. Tracheal extubation of the at-risk patient must also be carefully planned, including assessment of the patient's tolerance for withdrawal of airway support and whether re-intubation might be difficult.

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.

The Effectiveness of High-Flow Nasal Oxygen During the Intraoperative Period: A Systematic Review and Meta-analysis

BACKGROUND

High-flow nasal oxygen (HFNO) is increasingly being used in intensive care units for management of hypoxemia and respiratory failure. However, the effectiveness of HFNO for preventing hypoxemia in the intraoperative period is unclear. The purpose of this systematic review was to compare patient oxygenation and end-tidal CO2 (EtCO2), between HFNO and conventional oxygenation, during the intraoperative period in surgical patients.

METHODS

Standard databases were searched from inception to February 2020. Studies involving intraoperative use of HFNO with 1 of the 4 outcomes: (1) oxygen (O2) desaturation, (2) minimum O2 saturation, (3) safe apnea time, or (4) EtCO2 were included. Intraoperative period was divided into 2 phases: at induction with general anesthesia and during surgical procedure under sedation without tracheal intubation.

RESULTS

Eight randomized controlled trials (RCTs; 4 induction, 4 procedure, 2314 patients) were included for systematic review and meta-analyses. We found the risk of intraoperative O2 desaturation was lower in HFNO versus conventional oxygenation control group; at induction with an odds ratio (OR; 95% confidence interval [CI]) of 0.06 (0.01-0.59, P = .02), and during procedure, OR (95% CI) of 0.09 (0.05-0.18; P < .001). The minimum O2 saturation was higher in HFNO versus conventional oxygenation; at induction by a mean difference (MD) (95% CI) of 5.1% (3.3-6.9; P < .001), and during procedure, by a MD (95% CI) of 4.0% (1.8-6.2; P < .001). Safe apnea time at induction was longer in HFNO versus conventional oxygenation by a MD (95% CI) of 33.4 seconds (16.8-50.1; P < .001). EtCO2 at induction was not significantly different between HFNO and conventional oxygenation groups.

CONCLUSIONS

This systematic review and meta-analysis show that, in the intraoperative setting, HFNO compared to conventional oxygenation reduces the risk of O2 desaturation, increases minimum O2 saturation, and safe apnea time. HFNO should be considered for anesthesia induction and during surgical procedures under sedation without tracheal intubation in patients at higher risk of hypoxemia.

Metabolic syndrome - Evidence-based strategies for patient optimization

With the increasing prevalence of obesity worldwide, it is inevitable that anesthesiologists will encounter patients with metabolic syndrome. Metabolic syndrome encompasses multiple diseases, which include central obesity, hypertension, dyslipidemia, and hyperglycemia. Given the involvement of multiple diseases, metabolic syndrome involves numerous complex pathophysiological processes that negatively impact several organ systems. Some of the organ systems that have been well-documented to be adversely affected include the cardiovascular, pulmonary, and endocrine systems. Metabolic syndrome also leads to prolonged hospital stays, increased rates of infections, a greater need for care after discharge, and overall increased healthcare costs. Several interventions have been suggested to mitigate these negative outcomes ranging from lifestyle modifications to surgeries. Therefore, anesthesiologists should understand metabolic syndrome and formulate management strategies that may modify perianesthetic and surgical risks.

Noninvasive ventilation support during fiberoptic bronchoscopy-guided nasotracheal intubation effectively prevents severe hypoxemia

Purpose

This study investigated the feasibility and efficacy of continuous noninvasive ventilation (NIV) support with 100% oxygen using a specially designed face mask, for reducing desaturation during fiberoptic bronchoscopy (FOB)-guided intubation in critically ill patients with respiratory failure.

Materials and methods

This was a single-center prospective randomized study. All patients undergoing FOB-guided nasal tracheal intubation were randomized to bag-valve-mask ventilation or NIV for preoxygenation followed by intubation. The NIV group were intubated through a sealed hole in a specially designed face mask during continuous NIV support with 100% oxygen. Control patients were intubated with removal of the mask and no ventilatory support.

Results

We enrolled 106 patients, including 53 in each group. Pulse oxygen saturation (SpO₂) after preoxygenation (99% (96%–100%) vs. 96% (90%–99%), p = .001) and minimum SpO₂ during intubation (95% (87%–100%) vs. 83% (74%–91%), p < .01) were both significantly higher in the NIV compared with the control group. Severe hypoxemic events (SpO₂ < 80%) occurred less frequently in the NIV group than in controls (7.4% vs. 37.7%, respectively; p < .01).

Conclusions

Continuous NIV support during FOB-guided nasal intubation can prevent severe desaturation during intubation in critically ill patients with respiratory failure.

Trial registration: ClinicalTrials.gov, NCT02462668. Registered on 25 May 2015, https://www.clinicaltrials.gov/ct2/results?term=NCT02462668.

•

Our study is the first to evaluate NIV during FOB-guided nasotracheal intubation.

•

NIV support during FOB-guided nasotracheal intubation was effectively prevented severe desaturation during intubation.

•

We used a specially-designed intubation face mask to ensure that there was no interruption of NIV support during intubation.

Preoxygenation before intubation in adult patients with acute hypoxemic respiratory failure: a network meta-analysis of randomized trials

Background

Patients with acute hypoxemic respiratory failure are at risk for life-threatening complications during endotracheal intubation. Preoxygenation might help reduce the risk of hypoxemia and intubation-related complications. This network meta-analysis summarizes the efficacy and safety of preoxygenation methods in adult patients with acute hypoxemic respiratory failure.

Methods

We searched PubMed, EMBASE, and the Cochrane Library Central Register of Controlled Trials through April 2019 for randomized controlled trials (RCT) that studied the use of conventional oxygen therapy (COT), high-flow nasal cannula (HFNC), noninvasive ventilation (NIV), and HFNC and NIV as preoxygenation before intubation in patients with acute hypoxemic respiratory failure. Citations’ screening, study selection, data extraction, and risk of bias assessment were independently performed by two authors. The primary outcome was the lowest SpO₂ during the intubation procedure.

Results

We included 7 RCTs (959 patients). Patients preoxygenated with NIV had significantly less desaturation than patients treated with COT (mean difference, MD 5.53, 95% CI 2.71, 8.34) and HFNC (MD 3.58, 95% CI 0.59, 6.57). Both NIV (odds ratio, OR 0.43, 95% CI 0.21, 0.87) and HFNC (OR 0.49, 95% CI 0.28, 0.88) resulted in a lower risk of intubation-related complications than COT. There were no significant mortality differences among the use of NIV, HFNC, COT, and HFNC and NIV during preoxygenation.

Conclusions

In adult patients with acute hypoxemic respiratory failure, NIV is a safe and probably the most effective preoxygenation method.

Reducing kidney motion: optimizing anesthesia and combining respiratory support for retrograde intrarenal surgery: a pilot study

BACKGROUND

One of the greatest challenges presented with RIRS is the potential for movement of the stone within the operative field associated with diaphragm and chest respiratory excursions due to mechanical ventilation. To overcome this challenge, we propose in this pilot study a new general anesthesia technique combining high frequency jet ventilation (HFJV) with small volume mechanical ventilation (SVMV). Data regarding safety, feasibility and surgeons' impression was assessed.

METHODS

Patients undergoing RIRS for kidney stones from November 2017 to May 2018 were prospectively recruited to participate in the study. In each case after the beginning of general anesthesia (GA) with mechanical ventilation (MV) surgeons were asked to assess the mobility of the operative field and conditions for laser lithotripsy according to the developed questionnaire scale. The questionnaire consisted of 5 degrees of assessment of kidney mobility and each question was scored from 1 to 5, 1 being very mobile (extremely poor conditions for dusting) and 5 completely immobile (Ideal conditions for dusting). After the assessment GA was modified with combined respiratory support (CRS), reducing tidal volume and respiratory rate (small volume mechanical ventilation, SVMV) and applying in the same time transcatheter high frequency jet ventilation (HFJV) inside the closed circuit. After beginning of CRS, surgeons were once again asked to assess the mobility of the operative field and the conditions for laser lithotripsy. Main ventilation parameters were recorded and compared in both regimens.

RESULTS

A total of 38 patients were included in the study. The mean age was 49 (range 45-53) with a mean stone size of 10 mm (range 10-14) and Hounsfield unit of 1060 (range 930-1190). All patients underwent successful RIRS and no intraoperative complications occurred throughout the duration of the study. A statistically significant difference between ventilation parameters prior to and after CRS institution was detected in all cases, however their clinical impact was negligible. Despite this, assessment via the questionnaire scale point values varied significantly before and after the application of CRS and were 2.3 (2.1; 2.6) and 3.8 (3.7; 4.0) respectively (p < 0.001).

CONCLUSIONS

The novel combined respiratory approach consisting of HFJV and SVMV appears to provide better conditions for stone dusting through reduced respiratory kidney motion and is not associated with adverse health effects or complications.

TRIAL REGISTRATION

NCT03999255 , date of registration: 25th June 2019 (retrospectively registered).

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

BACKGROUND

Apneic oxygenation via the oral route using a buccal device extends the safe apnea time in most but not all obese patients. Apneic oxygenation techniques are most effective when tracheal oxygen concentrations are maintained >90%. It remains unclear whether buccal oxygen administration consistently achieves this goal and whether significant risks of hypercarbia or barotrauma exist.

METHODS

We conducted a randomized trial of buccal or sham oxygenation in healthy, nonobese patients (n = 20), using prolonged laryngoscopy to maintain apnea with a patent airway until arterial oxygen saturation (SpO2) dropped <95% or 750 seconds elapsed. Tracheal oxygen concentration, tracheal pressure, and transcutaneous carbon dioxide (CO2) were measured throughout. The primary outcome was maintenance of a tracheal oxygen concentration >90% during apnea.

RESULTS

Buccal patients were more likely to achieve the primary outcome (P < .0001), had higher tracheal oxygen concentrations throughout apnea (mean difference, 65.9%; 95% confidence interval [CI], 62.6%-69.3%; P < .0001), and had a prolonged median (interquartile range) apnea time with SpO2 >94%; 750 seconds (750-750 seconds) vs 447 seconds (405-525 seconds); P < .001. One patient desaturated to SpO2 <95% despite 100% tracheal oxygen. Mean tracheal pressures were low in the buccal (0.21 cm·H2O; SD = 0.39) and sham (0.56 cm·H2O; SD = 1.25) arms; mean difference, -0.35 cm·H2O; 95% CI, 1.22-0.53; P = .41. CO2 accumulation during early apnea before any study end points were reached was linear and marginally faster in the buccal arm (3.16 vs 2.82 mm Hg/min; mean difference, 0.34; 95% CI, 0.30-0.38; P < .001). Prolonged apnea in the buccal arm revealed nonlinear CO2 accumulation that declined over time and averaged 2.22 mm Hg/min (95% CI, 2.21-2.23).

CONCLUSIONS

Buccal oxygen administration reliably maintains high tracheal oxygen concentrations, but early arterial desaturation can still occur through mechanisms other than device failure. Whereas the risk of hypercarbia is similar to that observed with other approaches, the risk of barotrauma is negligible. Continuous measurement of advanced physiological parameters is feasible in an apneic oxygenation trial and can assist with device evaluation.

An Anesthesiologist's Perspective on the History of Basic Airway Management: The "Modern" Era, 1960 to Present

This fourth and last installment of my history of basic airway management discusses the current (i.e., "modern") era of anesthesia and resuscitation, from 1960 to the present. These years were notable for the implementation of intermittent positive pressure ventilation inside and outside the operating room. Basic airway management in cardiopulmonary resuscitation (i.e., expired air ventilation) was de-emphasized, as the "A-B-C" (airway-breathing-circulation) protocol was replaced with the "C-A-B" (circulation-airway-breathing) intervention sequence. Basic airway management in the operating room (i.e., face-mask ventilation) lost its predominant position to advanced airway management, as balanced anesthesia replaced inhalation anesthesia. The one-hand, generic face-mask ventilation technique was inherited from the progressive era. In the new context of providing intermittent positive pressure ventilation, the generic technique generated an underpowered grip with a less effective seal and an unspecified airway maneuver. The significant advancement that had been made in understanding the pathophysiology of upper airway obstruction was thus poorly translated into practice. In contrast to consistent progress in advanced airway management, progress in basic airway techniques and devices stagnated.

Difficult tracheal intubation in critically ill

Background

Endotracheal intubation in critically ill is a high-risk procedure requiring significant expertise in airway handling as well as understanding of pathophysiology of the disease process.

Main body

Critically ill patients are prone for hypotension and hypoxemia in the immediate post-intubation phase due to blunting of compensatory sympathetic response. Preoxygenation without NIV is frequently suboptimal, as alveolar flooding cause loss of alveolar capillary interface in many of these patients. All these factors, along with relative fluid deficit, neuromuscular fatigue and coexistent organ dysfunction lead to physiologically difficult airway. Airway in ICU can be classified as anatomically difficult, physiologically difficult and anatomically as well as physiologically difficult. Though rapid sequence intubation is the recommended method for securing airway in these patients, other methods like delayed sequence intubation awake intubation and double setup approach can be used in specific subgroups. Further research is needed in this field to set guidelines and fine tune airway management for patients with specific organ failure or dysfunction.

Conclusion

Airway in ICU should be managed according to the physiological as well as the anatomical abnormalities.

Tracheal intubation in critically ill patients: a comprehensive systematic review of randomized trials

BACKGROUND

We performed a systematic review of randomized controlled studies evaluating any drug, technique or device aimed at improving the success rate or safety of tracheal intubation in the critically ill.

METHODS

We searched PubMed, BioMed Central, Embase and the Cochrane Central Register of Clinical Trials and references of retrieved articles. Finally, pertinent reviews were also scanned to detect further studies until May 2017. The following inclusion criteria were considered: tracheal intubation in adult critically ill patients; randomized controlled trial; study performed in Intensive Care Unit, Emergency Department or ordinary ward; and work published in the last 20 years. Exclusion criteria were pre-hospital or operating theatre settings and simulation-based studies. Two investigators selected studies for the final analysis. Extracted data included first author, publication year, characteristics of patients and clinical settings, intervention details, comparators and relevant outcomes. The risk of bias was assessed with the Cochrane Collaboration's Risk of Bias tool.

RESULTS

We identified 22 trials on use of a pre-procedure check-list (1 study), pre-oxygenation or apneic oxygenation (6 studies), sedatives (3 studies), neuromuscular blocking agents (1 study), patient positioning (1 study), video laryngoscopy (9 studies), and post-intubation lung recruitment (1 study). Pre-oxygenation with non-invasive ventilation (NIV) and/or high-flow nasal cannula (HFNC) showed a possible beneficial role. Post-intubation recruitment improved oxygenation_, while ramped position increased the number of intubation attempts and thiopental had negative hemodynamic effects. No effect was found for use of a checklist, apneic oxygenation (on oxygenation and hemodynamics), videolaryngoscopy (on number and length of intubation attempts), sedatives and neuromuscular blockers (on hemodynamics). Finally, videolaryngoscopy was associated with severe adverse effects in multiple trials.

CONCLUSIONS

The limited available evidence supports a beneficial role of pre-oxygenation with NIV and HFNC before intubation of critically ill patients. Recruitment maneuvers may increase post-intubation oxygenation. Ramped position increased the number of intubation attempts; thiopental had negative hemodynamic effects and videolaryngoscopy might favor adverse events.

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

Background:

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

Aims:

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

Settings and Design:

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

Materials and Methods:

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

Statistical Analysis Used:

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

Results:

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

Conclusion:

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

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

Background:

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

Aim of the Study:

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

Settings and Design:

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

Subjects and Methods:

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

Statistical Analysis Used:

Chi-square test and Mann–Whitney test.

Results:

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

Conclusion:

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

Guidelines and algorithms for managing the difficult airway

The difficult airway constitutes a continuous challenge for anesthesiologists. Guidelines and algorithms are key to preserving patient safety, by recommending specific plans and strategies that address predicted or unexpected difficult airway. However, there are currently no "gold standard" algorithms or universally accepted standards. The aim of this article is to present a synthesis of the recommendations of the main guidelines and difficult airway algorithms.

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

Background and Aims:

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

Methods:

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

Results:

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

Conclusion:

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

Efficacy and Safety of Using High-Flow Nasal Oxygenation in Patients Undergoing Rapid Sequence Intubation

Objective

To assess the efficacy and safety of high-flow nasal oxygen (HFNO) therapy in patients undergoing rapid sequence intubation (RSI) for emergency abdominal surgery.

Methods

HFNO of 60 L.min^-1 at an inspiratory oxygen fraction of 1 was delivered 4 min before laryngoscopy and maintained until the patient was intubated, and correct intubation was verified by the appearance of the end-tidal CO₂ (EtCO₂) waveform. Transcutaneous oxygenation (SpO₂), heart rate and non-invasive mean arterial pressure were monitored at baseline (T0), after 4 min on HFNO (T1) and at the time of laryngoscopy (T2) and endotracheal intubation (ETI) (T3). An SpO₂ of <3% from baseline was recorded at any sampled time. The value of EtCO₂ at T3 was registered after two mechanical breaths. The apnoea time was defined as the time from the end of propofol injection to ETI. RSI was performed with propofol, fentanyl and rocuronium.

Results

Forty-five patients were enrolled. SpO₂ levels showed a statistically significant increase at T1, T2 and T3 compared with those at T0 (p<0.05); median SpO₂% (interquartile range) was 97% (range, 96%-99%) at T0, 99% (range, 99%-100%) at T1, 99% (range, 99%-100%) at T2 and 99% (range, 99%-100%) at T3. Minimal SpO₂ was 96%; no patient showed an SpO₂ of <3% from baseline; mean EtCO₂ at the time of ETI was 36±4 mmHg. Maximum apnoea time was 12 min.

Conclusion

HFNO is an effective and safe technique for pre-oxygenation in patients undergoing rapid sequence induction of general anaesthesia for emergency surgery.

Guidelines for the management of tracheal intubation in critically ill adults

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