Facilitating EndotracheaL Intubation by Laryngoscopy technique and Apneic Oxygenation Within the Intensive Care Unit (FELLOW)

Transcription

1 Facilitating EndotracheaL Intubation by Laryngoscopy technique and Apneic Oxygenation Within the Intensive Data Analysis Plan: Apneic Oxygenation vs. No Apneic Oxygenation Background Critically ill patients frequently require endotracheal intubation. Procedural complications including arterial oxygen desaturation, hypotension, aspiration, and esophageal intubation are common and predispose to negative patient outcomes. Desaturation is the most common factor associated with peri-intubation cardiac arrest and death. Administration of high flow oxygen via nasal cannula during airway management has been proposed as a method of preventing desaturation and has been studied in small cohorts of patients undergoing elective intubation in the operating room. The practice of apneic oxygenation has been promoted for use during intubation in acutely ill patients in the emergency department and intensive care unit. However, whether apneic oxygenation prevents desaturation during the intubation of critically ill patients remains unknown. Patient Population Adult patients undergoing intubation in the medical intensive care unit of an academic, tertiary care hospital. Inclusion Criteria 1. Patient undergoing intubation in the Medical ICU 2. Planned operator is a pulmonary and critical care medicine fellow 3. Administration of sedation and/or neuromuscular blockade is planned Exclusion Criteria 1. Operator or supervisor feels specific intra-procedural oxygenation technique will be required. Specific Hypothesis The primary hypothesis is that the provision of apneic oxygenation during the endotracheal intubation procedure (defined as a nasal cannula with 15 liters per minute of oxygen flow placed prior to sedation or neuromuscular blockade and maintained until after completion of the procedure) will result in a higher lowest oxygen saturation (defined as lowest noninvasive oxygenation saturation value observed between the administration of sedation and/or neuromuscular blockade and 2 minutes after successful endotracheal tube placement) compared to no apneic oxygenation. Variable Definitions

2 Primary Outcome The primary outcome will be lowest noninvasive oxygenation saturation value between administration of sedation and/or neuromuscular blockade and 2 minutes after successful endotracheal tube placement ( lowest oxygen saturation ). Secondary Outcomes Secondary efficacy outcomes will include: 1. Incidence of desaturation as defined by a decrease in oxygen saturation of greater than 3% from induction to lowest oxygen saturation (ex: 96% to 92%) 2. Incidence of hypoxemia as defined by lowest oxygen saturation less than 90% 3. Change in saturation from induction to lowest oxygen saturation 4. Lowest oxygen saturation adjusting for oxygen saturation at induction Secondary safety outcomes will include: 1. Incidence of first pass success defined as placement of an endotracheal tube in the trachea after the first insertion of the laryngoscope into the oral cavity without the use of any other devices 2. Grade of view on first attempt 3. Number of attempts required for tube placement 4. Time from induction to successful endotracheal tube placement 5. Incidence of need for additional intubating equipment 6. Incidence of non-hypoxia complications composite of all other recorded complications 7. Incidence of post-intubation tube malposition on CXR Tertiary Outcomes Tertiary outcomes will include: 1. In-hospital mortality 2. Ventilator-free days (VFDs) 3. ICU-free days Data Collection and Follow Up Baseline: Age, gender, height, weight, race, APACHE II score, active medical problems at the time of intubation, active comorbidities complicating intubation, mean arterial pressure and vasopressor use prior to intubation, noninvasive ventilator use, highest FIO2 delivered in prior 6 hours, lowest oxygen saturation in prior six hours, ph, PaO2, PaCO2, indication for intubation, reintubation, preoxygenation technique, operator experience, additional personnel available

3 Peri-procedural: Date and time of sedative and/or neuromuscular blocker administration, saturation at time of sedative and/or neuromuscular blocker administration, sedative, neuromuscular blocker, ventilation between induction and laryngoscopy, tube characteristics, route, laryngoscope type and size, total number of attempts, tube tape level, confirmation of placement technique, airway grade, airway difficulty, rescue device use, complications 0-6 hours: Post-intubation imaging, post intubation shock or cardiac arrest, SaO2, FIO2, PEEP, and MAP at 1 and 6 hours after intubation, In-Hospital Outcomes: Date of extubation, date of ICU discharge, date of death Treatment Allocation Opaque randomization envelopes will be present in the medical ICU and available to PCCM fellows when it is determined endotracheal intubation will be performed. Randomization will occur in permuted blocks of four to eight and the study personnel along with the operators will be blinded to the randomization assignments prior to the opening of an envelope. Once it has been determined by the treating team that (1) intubation is required, (2) the PCCM fellow will be the first to attempt the procedure, and (3) a specific intubating device or oxygenation strategy is not indicated, the operator will open the envelope and follow the assignment of either nasal cannula oxygen delivery during the entire procedure or no provision of a nasal cannula during the airway management procedure. Power and Sample Size Enrollment of 150 patients will provide 80 percent statistical power to detect a difference in the primary outcome of lowest oxygen saturation of 4-6 percent (ex: lowest oxygen saturation of 93% versus 88%) anticipating a standard deviation for the outcome between 10 and 15 using a Type I error rate of 0.05 (Figure 1)

4 Figure 1. Detectable difference in lowest oxygen saturation at 80% power for three possible standard deviations in lowest oxygen saturation value. Consent As apneic oxygenation during intubation and intubation without the administration of oxygen are both common in the current practice of endotracheal intubation of critically ill patients, and intubation is so commonly urgent that informed consent is not obtained for the majority of intubations as a part of routine care, a waiver of consent was granted for this study by the institutional review board at Vanderbilt. Statistical analysis Analysis principles Primary analysis will be conducted on an intention-to-treat basis (patients who have protocol violations are analyzed per the assigned treatment arm). All hypothesis tests will be two sided, with an α of 0.05 unless otherwise specified. All analyses are unadjusted unless otherwise specified. Subgroup analyses will be performed irrespective of treatment efficacy. Trial profile We will present a Consolidated Standards of Reporting Trials diagram as Figure 1 to detail the movement of patients through the study. This diagram will include total number of patients meeting inclusion criteria, number excluded and

5 reason for exclusion, number enrolled and randomized in the study, number followed, and number analyzed. Baseline comparisons and assessment of randomization To assess randomization success, we will summarize in Table 1 the distribution of baseline variables across the study arms. Categorical variables will be reported as frequencies and percentages and continuous variables as either means with SDs or medians with interquartile ranges. Variables reported will include Demographics (age, gender, race, BMI, ); Indication for intubation; Reintubation status; Active illnesses at the time of intubation; Severity of Illness (APACHE II score); Active comorbidities complicating intubation (vomiting, upper GI bleeding, etc); Respiratory status pre-intubation (NIV use, lowest O2 saturation, FiO2); Airway management procedure (Preoxygenation technique, Saturation at time of induction, Induction medication, Neuromuscular blocker, Laryngoscope type, operator experience with laryngoscope type) Primary Analysis Unadjusted test of treatment effect We will test the hypothesis that apneic oxygenation is superior to no apneic oxygenation by comparing the lowest oxygen saturation from induction until two minutes after placement of an intra-tracheal airway ( lowest oxygen saturation ) in patients randomized to the apneic oxygenation versus no apneic oxygenation groups. The primary outcome of lowest oxygen saturation will be treated as a continuous variable and the difference between the two groups will be compared using the Mann-Whitney U test. All other comparisons will be considered secondary analyses. Secondary Analyses Analysis of Secondary Outcomes (1) We will test the hypothesis that apneic oxygenation compared to no apneic oxygenation decreases the incidence of intra-procedural hypoxemia as defined by a lowest oxygen saturation of 90% or less. The presence or absence of desaturation by this dichotomization will be treated as a categorical variable and difference in the incidence between the two study arms will be analyzed using Fischer exact testing. (2) We will repeat the analysis above using the categorical outcome of desaturation as defined by a decrease in oxygen saturation from the time of induction to the lowest oxygen saturation of greater than 3%. (3) We will test the hypothesis that apneic oxygenation decreases the decline in oxygen saturation compared to no apneic oxygenation by comparing the two

6 randomized groups with respect to the change in saturation from induction to lowest oxygen saturation using the Mann-Whitney U test. (4) We will test the impact of apneic oxygenation on the following safety outcomes by comparing the following endpoints between the two randomized groups using the respective statistical methods: Grade of view on first attempt (Mann-Whitney U test), Number of attempts required for tube placement (Mann-Whitney U test), Incidence of need for a second operator (Fisher exact test), Incidence of need for additional intubating equipment (Fischer s exact test), incidence of non-hypoxia complications composite of all other recorded complications (Fisher s exact test), incidence of post-intubation tube malposition on CXR (Fisher s exact test) (5) We will test the impact of apneic oxygenation on complications unrelated to oxygenation by using Fischer exact testing to compare a composite of all other recorded complications between the intervention and control arms. Analysis of Tertiary Outcomes We will assess the impact of apneic oxygenation versus no apneic oxygenation on in-hospital mortality using Fisher exact testing. We will assess the impact of apneic oxygenation versus no apneic oxygenation on VFDs and ICU-free days using Mann-Whitney U testing. Per-Protocol Analysis of Primary Outcome We will test the hypothesis that receipt of apneic oxygenation is associated higher lowest oxygen saturation than no receipt of apneic oxygenation in a prespecified per-protocol analysis comparing lowest oxygen saturation as a continuous variable using the Mann-Whitney U test between patients who received apneic oxygenation and those that did not, regardless of randomized study group assignment. Subgroup Analyses We will repeat the intention-to-treat comparison of patients randomized to apneic oxygenation versus no apneic oxygenation with respect to the outcome of lowest oxygen saturation using the Mann-Whitney U test in the following subgroups: Subgroups available at procedure initiation 1. Oxygen saturation at induction below 95% 2. Highest FIO2 in the 6 hours prior to intubation above 50% 3. BIPAP use in the 6 hours prior to intubation 4. BMI above 30 kg/m2 Subgroups related to procedural performance

7 1. Laryngoscope type 2. Grade I and II view; grade III and IV view 3. Easy airway; Moderate or difficult airway 4. Duration of airway management above and below the median 5. Number of attempts required, 1 and >1 6. Experience of operator, greater than or less than 25 prior airways Modeling to Examine Potential Confounding Factors We will fit a linear regression model for the primary outcome of lowest oxygen saturation in which the variable of randomized group assignment (apneic oxygenation versus no apneic oxygenation) will be accompanied initially but just oxygen saturation by induction and then by potential baseline confounders including age, BMI, APACHE II score, shock, BIPAP use, highest FIO2 in 6 hours prior to intubation, oxygen saturation at induction, laryngoscope type, and operator experience. Modeling to Examine Potential Interactions We will fit a logistic regression model with the above covariates and will sequentially add an interaction term between randomized study group (apneic oxygenation versus no apneic oxygenation) and each of the subgrouping variables defined above (ex Laryngoscope type*study group, BIPAP*study group, BMI*study group, etc). Missing Data In the initial analysis, cases with data missing for the primary endpoint will not be included. As sensitivity analyses, the primary analysis will be repeated with missing data imputed by (1) carrying forward the saturation at the time of induction to the lowest oxygen saturation values, (2) carrying forward saturation from induction to lowest oxygen saturation for patients in the no apneic oxygenation arm and assigning a value of zero to the lowest oxygen saturation for those missing values in the apneic oxygenation arm (most conservative), and (3) carrying forward saturation from induction to lowest oxygen saturation for patient in the apneic oxygenation arm and assigning a value of zero to the lowest oxygen saturation for those missing values in the no apneic oxygenation arm (least conservative). Conclusion We describe, before the completion of enrollment or data unblinding, our approach to analyzing the data from the FELLOW study. We anticipate that this prespecified framework will enhance the utility of the reported result and allow readers to better judge the impact. Acknowledgments

8 We appreciate the help and support of the Vanderbilt MICU nurses and staff, attendings, fellows, and residents without whom this study would not have been possible. Funding None.