Still making the case against prehospital intubation: a rat hemorrhagic shock model

J Trauma Acute Care Surg. 2012 Aug;73(2):332-7; discussion 337. doi: 10.1097/TA.0b013e3182584447.


Background: Prehospital intubation does not appear to result in a survival advantage for patients experiencing penetrating trauma; yet, there is still resistance to the practice of "scoop and run" to speed access to advanced care. An animal model was used to determine whether intubation provides a survival advantage during potentially lethal hemorrhage.

Methods: The carotid arteries of Sprague-Dawley rats were cannulated, and mean arterial pressure (MAP) was measured. One group of animals (n = 10) was intubated and placed on a ventilator, whereas the other (n = 9) was administered with 100% oxygen via nose cone. Rats were exsanguinated to a MAP of 40 mm Hg and then bled periodically to maintain a MAP between 40 mm Hg and 45 mm Hg. The primary end-point was time until death. Secondary end-points included lactic acid and base excess levels measured in blood collected at 30-minute intervals after inducing shock.

Results: There was no significant difference in time until death between the intubated and nose cone groups (85.5 vs. 93.3 minutes, p = 0.60). Intubated animals had higher lactic acid levels at 90 minutes (6.1 vs. 3.5 mmol/L; p = 0.02) and 120 minutes (7.7 vs. 2.6 mmol/L, p = 0.03) after the initiation of shock. In addition, intubated animals had worse base excess at 90 minutes (-13.5 vs. -7.9 mmol/L, p = 0.04).

Conclusion: Intubation does not result in a survival advantage in this rat model of hemorrhagic shock. Positive pressure ventilation may cause decreased venous return and accentuate end-organ hypoperfusion. Large animal studies are needed to further investigate these findings.

Publication types

  • Comparative Study

MeSH terms

  • Analysis of Variance
  • Animals
  • Blood Chemical Analysis
  • Cause of Death*
  • Disease Models, Animal
  • Emergency Medical Services / standards
  • Emergency Medical Services / trends
  • Humans
  • Intubation, Intratracheal / methods*
  • Kaplan-Meier Estimate
  • Male
  • Positive-Pressure Respiration / methods
  • Random Allocation
  • Rats
  • Rats, Sprague-Dawley
  • Risk Assessment
  • Shock, Hemorrhagic / mortality*
  • Shock, Hemorrhagic / therapy*
  • Survival Rate
  • Wounds, Penetrating / mortality
  • Wounds, Penetrating / therapy