Cardiac Arrest Complicating Emergency Airway Management

Emergency airway management and specifically intubation can be associated with significant adverse events, related to the airway itself (failed intubation, oesophageal intubation and hypoxia being amongst the most common), or related to haemodynamic instability, with post intubation hypotension being a recognised complication.

Cardiac arrest is associated with emergency intubation and occurs in about in about 2.4% of cases, which is far more common than the recognised 1 in 10,000(1) events during elective anaesthesia. 

Is it possible to better predict these patients and thus take steps to ensure we avoid this?

Heffner et al (2) conducted this study " to identify the incidence of clinical factors associated with peri-intubation CA (cardiac arrest) during emergency airway management"

What They Did

This was a retrospective cohort study.
it included all patients undergoing emergency endotracheal intubation.

The time point where emergency airway management was seen to commence was defined as the administration of a drug to facilitate intubation.

Patients were divided into two groups: those with and those without cardiac arrest. 
Peri-intubation cardiac arrest was defined as occurring within 60 minutes of advanced airway management, early cardiac arrest, was defined as occurring within 10 minutes.

Peri-intubation hypotension was defined as systolic blood pressure(SBP) < 90 mm Hg or the need for vasopressor support within 30 minutes of the procedure.

Shock Index = heart rate/systolic blood pressure

N=410

What They Found

• Peri-intubation cardiac arrest occurred in 17 patients (4.2% of patients)
• Median time from RSI drug administration to arrest was 6 minutes
• Early peri-intubation cardiac arrest (within 10 minutes) occurred in 2.4%
• PEA was the initial rhythm in 88% of cardiac arrests.
  • This is a much higher rate of PEA than is normally associated with cardiac arrest.
• ROSC was achieved in 9 patients
• Peri-intubation cardiac arrest was associated with a 14 fold increase in odds of hospital death, compared to those with no cardiac arrest.
• Those patients who had a cardiac arrest were more likely to:
  • Have a lower systolic blood pressure
    • Cardiac arrest occurred within 30 minutes in 12%(9/74) of patients with hypotension, compared to 3% (8/300) without pre-RSI hypotension
  • Have a higher Shock Index (> 0.9)
  • Oxygen saturation < 92%
    • This was more common in those patients who had cardiac arrest, although was not independently associated with cardiac arrest.
• They found that weight and Shock Index were independently associated with peri-intubation cardiac arrest. 
  
  • The odds of cardiac arrest increased 1.37x for every extra 10kg increase in weight.

What this means

There are some limitations to this study as it was retrospective and conducted at a single centre. However the results are consistent with what we intuitively know.

The rate of cardiac arrest was 1 in 25 intubations. A very high rate compared to 1 in 10,000, which is the elective anaesthesia rate of peri-intubation cardiac arrest.

Variables that were identified as being important and ones that we must pay attention to when preparing to secure the emergency airway are:

• Hypotension
  • SBP < 90 mm Hg
  • Shock Index > 0.9
• Hypoxaemia
• Specialised steps to dealing with the airway in the bariatric patient.

References

1. Zuercher M, Ummenhofer W. Cardiac arrest during anesthesia. Curr Opin Crit Care 2008;14:269–74.
2. Heffner AC et al. Incidence and factors associated with cardiac arrest complicating emergency airway management. Resuscitation 84(2013) 1500-1504.