Incidence of hypo- and hypercarbia in severe traumatic brain injury before and after 2003 pediatric guidelines*

Curry, Rebecca MSII; Hollingworth, Will PhD; Ellenbogen, Richard G.; Vavilala, Monica S. MD

From the School of Medicine (RC) and Departments of Radiology (WH), Pharmacy (WH), Neurological Surgery (RGE, MSV), and Anesthesiology (MSV), University of Washington; and Harborview Injury Prevention and Research Center (WH, RGE, MSV), Seattle, WA.

*See also p. 230.

Supported, in part, by grant NIH K23 HD044632-05 from the National Institutes of Health, Bethesda, MD (MSV), and by the University of Washington Medical Student Research Training Program (RC).

The authors have not disclosed any potential conflicts of interest.

For information regarding this article, E-mail:[email protected]

Pediatric Critical Care Medicine9(2):p 141-146, March 2008. |DOI:10.1097/PCC.0B013e318166870e

Abstract

Objective:

To examine the incidence of severe hypocarbia (Paco₂ <30 mm Hg) in patients with severe pediatric traumatic brain injury before and after publication of the 2003 pediatric guidelines (PG).

Design:

Retrospective cohort analysis.

Setting:

Harborview Medical Center, Seattle, Washington (January 1, 1995, to December 31, 2005).

Patients:

Children <15 yrs of age with severe pediatric traumatic brain injury.

Interventions:

None.

Measurements and Main Results:

The pre-PG group (before August 1, 2003) included 375 patients and the post-PG group included 89 patients. Post PG guidelines, there was a trend toward earlier (45 vs. 32 mins;p = .05) and more frequent (7.1 vs. 8.4 samples;p = .06) Paco₂ sampling within 48 hrs of admission. Children 0–2 yrs had a longer time (75.0 mins) between admission and first Paco₂ sample than older children (44.3 mins;p < .01). The youngest children also had the highest incidence of severe hypocarbia on the first Paco₂ sample (31% vs. 19%;p = .02). Incidence of severe hypocarbia was high and did not decline (60% vs. 52%;p = .2) after the PG guidelines. However, over the 11 yrs, the odds of severe hypocarbia decreased (adjusted odds ratio 0.9; 95% confidence interval 0.84–0.96). During both periods, the incidence of severe hypocarbia was highest during the first 2 hrs after hospital admission. Intracranial pressure monitors were used more frequently post-PG. In 62 of 82 (77%) patients with severe hypocarbia in whom an intracranial pressure monitor was in place, the preceding intracranial pressure was <20 mm Hg. Severe hypocarbia independently predicted inpatient mortality (adjusted odds ratio 2.8; 95% confidence interval 1.3–5.9).

Conclusions:

Although Paco₂ sampling was more frequent during the post-PG period and severe hypocarbia decreased during successive study years, the incidence of severe hypocarbia remained high during the first 48 hrs after hospital admission during the post-PG period. Time to Paco₂ sampling was longer in young children and associated with more severe hypocarbia. The presence of severe hypocarbia predicted mortality.