Submitted on November 5, 2004
Accepted on August 15, 2005
Buccal Capnometry to Guide Management of Massive Blood Loss
Gianluca A.A.M. Cammarata1, Max Harry Weil2*, Michael Fries1, Wanchun Tang2, Shijie Sun2, and Carlos J. Castillo1
1 Weil Institute of Critical Care Medicine, Rancho Mirage, CA, USA
2 Weil Institute of Critical Care Medicine, Rancho Mirage, CA, USA; Keck School of Medicine, USC, Los Angeles, CA, USA
* To whom correspondence should be addressed. E-mail: Weilm{at}911research.org.
In both clinical and experimental settings, tissue PCO2 measured in the oral mucosa is a practical and reliable measurement of the severity of hypoperfusion. We hypothesized that a threshold level of buccal tissue PCO2 (PBUCO2) would prognosticate the effects of volume repletion on survival. Twenty pentobarbital anesthetized Sprague-Dawley male breeder rats, each weighing approximately 0.5 kg, were randomly assigned to one of four groups. Animals were bled over an interval of 30 min in amounts estimated to be 25, 30, 35 or 40% of total blood volume. One half an hour after the completion of bleeding, each animal received an infusion of Ringer's lactate solution over the ensuing 30 min in amounts equivalent to two times the volume of blood loss. Buccal PCO2 was measured continuously with an optical PCO2 sensor applied non-invasively to the mucosa of the left cheek. Arterial pressure and end-tidal CO2 (PETCO2) were measured over the same interval. Neurological deficit and 72-hour survival were recorded. Aortic pressures were restored to near baseline values for each of the four groups after fluid resuscitation. This contrasted with the improvement of PBUCO2 which differentiated between animals with short and long durations of post intervention survival. After electrolyte fluid resuscitation in rats subjected to rapid bleeding, non-invasive measurement of PBUCO2 was predictive of outcomes. Neither non-invasive PETCO2 nor invasive aortic pressure measurements achieved such discrimination. Accordingly, PBUCO2 fulfills the criterion of a non-invasive and reliable measurement to guide fluid management of hemorrhagic shock.
