Use of High-Flow Nasal Cannula Oxygen Therapy to Prevent Desaturation During Tracheal Intubation of Intensive Care Patients With Mild-to-Moderate Hypoxemia*

Summary by Robbert Webber, MD 10.11.23
https://pubmed.ncbi.nlm.nih.gov/25479117/

Clinical Hypothesis: Compare pre- and per-procedure oxygenation with either a nonrebreathing bag reservoir facemask or a high-flow nasal cannula oxygen during tracheal intubation of ICU patients.

Take Home Message: 

  • High flow nasal cannula (HFNC) significantly improved SpO2 while preventing hypoxemia during ICU intubation compared to non-rebreather mask (NRM),

  

Summary:

 

Background:  Tracheal intubation in the ICU is associated with increased morbidity and (in some cases) mortality with 1 in 3 intubations associated with at least 1 severe complication, most often severe hypoxemia. Previous efforts to improve preoxygenation through conventional facemask oxygenation/ventilation were found to only be marginally effective. Non-invasive ventilation (NIV), either through positive-pressure ventilation or non-rebreather mask (NRM), has been shown to reduce the prevalence and magnitude of desaturation during intubation by enhancing preoxygenation, however, this process is normally interrupted during intubation by laryngoscopy leading to potential hypoxemic events. This study determined if HFNC can improve oxygenation and reduce severe hypoxemia during intubation compared to NRM.

 

Study Design: Prospective quasi-experimental before/after

 

Methods: 

Inclusion criteria: Adult patients admitted to the ICU and requiring endotracheal intubation.

 

Exclusion criteria: Age under 18, intubation for cardiac arrest, severe hypoxemia (SpO2 <95% on NRM of 15 L/min), pts currently on HFNC or NIV, or patients requiring awake fiber optic intubation.

  

Primary outcome: Lowest SpO2 value observed in each patient

Secondary outcome: Median SpO2 after preoxygenation, during intubation, after intubation, and prevalence of life-threatening hypoxia (defined as SpO2 <80%) during procedure. Additionally, prevalence of serious adverse events (cardiac arrest, sustained arrhythmia, and hemodynamic instability) were also recorded.

 

Results: The initial SpO2 was 100% in both groups (NRM vs HFNC). There was a greater incidence of hypoxemia in NRM group (median 94% SpO2 vs 100% SpO2, p=0.0001) along with severe hypoxemia (SpO2 <80%) in the NRM group (14% vs 2%, p=0.03). In multivariate analysis, HFNC was an independent protective factor in the occurrence of severe hypoxemia (OR 0.14, 95% CI, p=0.037).

Discussion: Life-threatening hypoxemia is the most frequently reported complication of intubation in the ICU despite preoxygenation. There are numerous reasons for this: cardiopulmonary underlying disease, anemia, low-cardiac output, hypermetabolic states, V/Q mismatch, obesity, pain, difficult intubation, etc. Therefore, improving preoxygenation is critical in reducing morbidity or urgent tracheal intubation in the ICU. While NIV (mainly positive-pressure ventilation) has proven to reduce hypoxemic events, it has inherent limitations such as: acceptance and cooperation of the patient along with subsequent removal during laryngoscopy. On the other hand, HFNC does not require the patient’s cooperation and it has the ability to deliver a high FiO2 along with a certain amount of positive pressure all of which contribute to “apneic oxygenation” during laryngoscopy, thereby reducing hypoxemic events during intubation. The limitations of this study include not being a true randomized control trial (which was not pursued due to ethical reasons), the inspired/expired O2 concentration was not measured (mainly due to not finding a device able to adapt satisfactorily to HFNC), and the clinical significance of the SpO2 measurements along with the standard deviation of the pulse ox (which was ± 2%, which was why a more significant outcome measurement (<80% SpO2) was chosen). The strengths of this study include the trial conducted in an actual ICU with ICU patients, the number of patients in the trial, and the exclusion of the sickest patients in the ICU (to which one would assume HFNC would benefit the most). 

Conclusion: Use of HFNC for preoxygenation during ICU intubation significantly reduced the prevalence of severe hypoxemia compared to NRM.