A score to predict difficulty of intubation in ICU patients underwent derivation and validation in French ICUs. The main predictors included Mallampati score III or IV, obstructive sleep apnoea syndrome, reduced mobility of cervical spine, limited mouth opening, severe hypoxia, coma, and where the operator was a nonanesthesiologist.
The striking thing is the overall rate of difficult intubations, defined as three or more laryngoscopy attempts or taking over 10 minutes using conventional laryngoscopy(!) and the high rate of severe complications.
The incidence of difficult intubation was 11.3% (113 of 1,000 intubation procedures) in the original cohort and 8% (32 of 400 intubation procedures) in the validation cohort.
In the development cohort, overall complications occurred in 437 of 1,000 intubation procedures (43.7%), with 381 (38.1%) severe complications (26 cardiac arrests, 2.6%; five deaths, 0.5%; 274 severe collapses, 27.4%; 155 severe hypoxemia, 15.5%) and 112 (11.2%) moderate complications (15 agitations, 1.5%; 32 cardiac arrhythmias, 3.2%; 23 aspirations, 2.3%; 48 esophageal intubations, 4.8%; six dental injuries, 0.6%).
There is no comment on incidence of propofol use for induction; I was tempted to speculate whether it was implicated in any of the cardiac arrests – something we observe time and again in the critically ill – but the authors state: “The drugs used for intubation, in particular neuromuscular blockers, did not differ between groups… However, midazolam use was more frequent in case of difficult intubation.”
Capnography was used only in 46% of intubations, and there was no mention of checklist use. It is fascinating how some aspects of airway management that might be considered minimum and basic safety standards in some practice settings are not yet routine in other specialties or locations.
An interesting study, from which one of the take home messages for me has to be a resounding ‘Yikes!’.
Early Identification of Patients at Risk for Difficult Intubation in the Intensive Care Unit
Am J Respir Crit Care Med. 2013 Apr 15;187(8):832-9
[EXPAND Abstract]

Rationale: Difficult intubation in the intensive care unit (ICU) is a challenging issue.

Objectives: To develop and validate a simplified score for identifying patients with difficult intubation in the ICU and to report related complications.

Methods: Data collected in a prospective multicenter study from 1,000 consecutive intubations from 42 ICUs were used to develop a simplified score of difficult intubation, which was then validated externally in 400 consecutive intubation procedures from 18 other ICUs and internally by bootstrap on 1,000 iterations.

Measurements and Main Results: In multivariate analysis, the main predictors of difficult intubation (incidence = 11.3%) were related to patient (Mallampati score III or IV, obstructive sleep apnea syndrome, reduced mobility of cervical spine, limited mouth opening); pathology (severe hypoxia, coma); and operator (nonanesthesiologist). From the β parameter, a seven-item simplified score (MACOCHA score) was built, with an area under the curve (AUC) of 0.89 (95% confidence interval [CI], 0.85-0.94). In the validation cohort (prevalence of difficult intubation = 8%), the AUC was 0.86 (95% CI, 0.76-0.96), with a sensitivity of 73%, a specificity of 89%, a negative predictive value of 98%, and a positive predictive value of 36%. After internal validation by bootstrap, the AUC was 0.89 (95% CI, 0.86-0.93). Severe life-threatening events (severe hypoxia, collapse, cardiac arrest, or death) occurred in 38% of the 1,000 cases. Patients with difficult intubation (n = 113) had significantly higher severe life-threatening complications than those who had a nondifficult intubation (51% vs. 36%; P < 0.0001).
Conclusions: Difficult intubation in the ICU is strongly associated with severe life-threatening complications. A simple score including seven clinical items discriminates difficult and nondifficult intubation in the ICU.

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