Online Letters to the Editor
To the Editor:
We read with great interest the article published in a recent issue of Critical Care Medicine by De Jong et al (1), who retrospectively investigated the prevalence of and risk factors for cardiac arrest during intubation in an ICU. They demonstrated that the prevalence of cardiac arrest during intubation was as high as 2.7%, and five factors (arterial hypotension, hypoxemia, lack of preoxygenation, overweight/obesity, and age > 75 yr) were independent risk factors for cardiac arrest. We appreciate this research for identifying the risk factors for cardiac arrest during intubation, some of which are preventable and could contribute to improvements in the risk of death.
However, several factors that could have potentially affected the study results should be discussed. First, the procedures, definitions, and achievement rate of preoxygenation used in the study by De Jong et al (1) were unclear. During the study period (from 2001 to 2016), many preoxygenation techniques were developed for intubation. Common techniques included breathing high-flow oxygen for a minimum of 3 minutes (2). Jaber et al (3) demonstrated that adding high-flow nasal cannula (HFNC) oxygen to noninvasive ventilation (NIV) as preoxygenation reduced oxygen desaturation during intubation compared with NIV alone. Frat et al (4) recently showed that NIV alone in comparison to HFNC alone decreased the number of episodes of severe hypoxemia during intubation in the ICU. These results suggested that preoxygenation can affect the subsequent hypoxemia, which is potentially associated with the risk of death.
Second, the lowest peripheral capillary oxygen saturation before intubation seemed to be very low compared with clinical practice (82% overall, 62% in the cohort with cardiac arrest). In addition, the timing and duration of this hypoxemia were unclear. Despite the current concept of permissive hypoxemia among critically ill patients, the acceptable value is commonly as low as 85%. The severe hypoxemia before intubation observed in the study by De Jong et al (1) might have affected the occurrence of cardiac arrest.
Third, the Sequential Organ Failure Assessment (SOFA) score did not appear to be included in the risk analysis of cardiac arrest. The authors demonstrated that SOFA score was significantly more severe in the intubation-related cardiac arrest cohort compared with the no cardiac arrest cohort (8 vs 5, respectively; p = 0.039). Multivariate analysis including the SOFA score would, therefore, be helpful to identify independent risk factors for cardiac arrest.
In conclusion, we suggest that the authors should provide additional data to elucidate the risk factors for cardiac arrest during intubation in ICU.
Yuko Tanabe, MD, Shinichiro Ohshimo, MD, PhD, Nobuaki Shime, MD, PhD
, Department of Emergency and Critical Care Medicine, Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan
1. De Jong A, Rolle A, Molinari N, et alCardiac Arrest and Mortality Related to Intubation Procedure in Critically Ill Adult Patients: A Multicenter Cohort Study. Crit Care Med 2018; 46:532–539
2. Pourmand A, Robinson C, Dorwart K, et alPre-oxygenation: Implications in emergency airway management. Am J Emerg Med 2017; 35:1177–1183
3. Jaber S, Monnin M, Girard M, et alApnoeic oxygenation via high-flow nasal cannula oxygen combined with non-invasive ventilation preoxygenation for intubation in hypoxaemic patients in the intensive care unit: The single-centre, blinded, randomised controlled OPTINIV trial. Intensive Care Med 2016; 42:1877–1887
4. Frat JP, Ricard JD, Coudroy R, et alon-behalf-of REVA network: Preoxygenation with non-invasive ventilation versus high-flow nasal cannula oxygen therapy for intubation of patients with acute hypoxaemic respiratory failure in ICU: The prospective randomised controlled FLORALI-2 study protocol. BMJ Open 2017; 7:e018611