Sometimes putting the tube in is the easy part: when to intubate in hypoxic respiratory failure.
Ethan L. Sanford MD, Shawn Jackson MD PhD, Justin L. Lockman MD MSEd
Original review article
Lee KG, Roca O, Casey JD, Semler MW, Roman-Sarita G, Yarnell CJ, Goligher EC. When to intubate in acute hypoxaemic respiratory failure? Options and opportunities for evidence-informed decision making in the intensive care unit. Lancet Respir Med. 2024 Aug;12(8):642-654. doi: 10.1016/S2213-2600(24)00118-8. Epub 2024 May 24. Erratum in: Lancet Respir Med. 2024 Aug;12(8):e51. doi: 10.1016/S2213-2600(24)00209-1. PMID: 38801827.
Trainees in anesthesia, and from other specialties, often arrive in the operating room excited to “learn” how to intubate. Of course, they (just like most of us were, once upon a time) are most interested in learning how to put the tube in! Often the more nuanced decision is the knowing when to intubate. Today’s PAAD reviews intubation timing, physiologic triggers for intubation, and challenges to research in this domain for ADULT patients in hypoxemic respiratory failure. As opposed to adults, children in the ICU often require sedation for bedside procedures including central venous cannulation, chest tube placement, paracentesis, or lumbar puncture – even in the absence of respiratory failure. When considering these and other cases, intubation may be part of a safe sedation/anesthetic plan, but in critically ill children this decision may result in prolonged intubation and mechanical ventilation with all the associated complications. Pediatric anesthesiologists should be the experts in weighing the risks and benefits of airway management strategies. There is usually no “risk free” choice. Similarly, early intubation vs. prolonged use of non-invasive positive pressure is a matter of some controversy in the critical care literature – with risks and benefits to both.
Lee et al.1 offer some insight, at least for adults in their review. This topic was highlighted during the COVID-19 pandemic during which delayed intubation was emphasized based on case reports and observational data suggesting increased mortality among intubated patients. Of course, the confounding of worsened health status leading to intubation make these data difficult to interpret. Importantly, subsequent analysis did not support delayed intubation.2
This review highlights various parameters that clinicians may use to assess physiologic status, including: PaO2/FiO2 ratio, ROX index (ratio of oxygen saturation to respiratory rate), VOX index (SpO2/FiO2)/tidal volume, and rapid shallow breathing index (RSBI), among others. Each of these demonstrates association with eventual intubation in observational studies. A shared weakness is that most of these parameters do not consider respiratory support (high flow oxygen, mean airway pressure from non-invasive support, and sometimes FiO2) when comparing one patient or condition to another. The authors point out that “showing that eventual intubation is probable is not the same as showing that immediate intubation is beneficial”. Finally, the impact of anesthetic medications on these respiratory parameters and the need for intubation is not clearly defined. These parameters should not be weaponized to force decisions, but used as tools to assess risk and choose the anesthetic technique which will serve the patient best.
These tools are often used to apply more rigorous clinical trial methodologies wherein an intervention (high flow nasal cannula, non-invasive positive pressure) is tested for effect on intubation need. Further, these criteria can be adjusted to be more or less permissive of early intubation. Any criterion which results in fewer intubations may also lead to greater risk of adverse outcomes with delayed intubation.3 Falsely applying binary criteria to the continuous spectrum of respiratory illness may be inadequate. Rather than a clear dichotomy, the relative benefits and risks of differing strategies must be weighed.
Pediatric anesthesiologists interact with children throughout the spectrum of respiratory pathology. Our sedative and analgesic agents often depress respiratory function, alter physiology, and thus may prompt consideration of intubation. However, the risks of longer-term intubation and mechanical ventilation, including ventilator associated pneumonia, sedative dependence and delirium, and ventilator-associate lung injury should not be minimized in critically ill-children. There are scant data to guide these decisions, leading us to weigh risks and benefits carefully for each individual patient. In our experience, anesthesiologists sometimes choose a strategy which minimizes perianesthetic risks at the expense of these longer-term risks in critically ill children. While we should all agree that safe anesthesia is critical, we advocate that the longer-term impact of our care be weighed properly. Current systems to assess our decisions may favor minimizing risk during the anesthetic. M&M’s and root care analysis (RCAs) often focus on events during the anesthetic and seldom even recognize complications of our decisions days to weeks down the line. However, the route to the best patient outcome is, in most cases, the one we should choose even if it makes the anesthetic care more complicated, and potentially risky. Explanation of competing risks with differing strategies with parents may be confusing but is likely important in allowing parents to understand the clinical decisions we recommend. Parents of critically ill children are sadly accustomed to risk, perhaps we can relieve some of their burden by explaining the realities of the decisions we make with them.
Do you or your colleagues utilize specific physiologic or laboratory parameters to determine the need for peri-anesthetic intubation? Is there an emphasis on extubating even when respiratory dynamics are not completely normal? How do you discuss peri-anesthetic risk and intubation risks with families for critically ill children undergoing minor procedures? Email Myron at myasterster@gmail.com and he’ll post in a Friday Reader Response.
PS from Myron: For a deeper dive into the role of anesthesiologists during the COVID epidemic please attend the 2024 Emery A. Rovenstine Memorial Lecture: Our Finest Hour: How Anesthesiologists Saved Countless Lives during the COVID-19 Pandemic, which will be presented on Monday, October 21, 8 – 9:15 a.m by Mary Dale Peterson, MD, MSHCA, FACHE, FASA at the ASA’s annual meeting in Philadelphia PA
References
1. Lee KG, Roca O, Casey JD, et al. When to intubate in acute hypoxaemic respiratory failure? Options and opportunities for evidence-informed decision making in the intensive care unit. Lancet Respir Med 2024;12(8):642-654. (In eng). DOI: 10.1016/s2213-2600(24)00118-8.
2. Ridjab DA, Ivan I, Budiman F, Juzar DA. Outcome in early vs late intubation among COVID-19 patients with acute respiratory distress syndrome: an updated systematic review and meta-analysis. Sci Rep 2022;12(1):21588. (In eng). DOI: 10.1038/s41598-022-26234-7.
3. Kang BJ, Koh Y, Lim CM, et al. Failure of high-flow nasal cannula therapy may delay intubation and increase mortality. Intensive care medicine 2015;41(4):623-32. (In eng). DOI: 10.1007/s00134-015-3693-5.