Evaluation of end-tidal carbon dioxide as a predictor of return of spontaneous circulation in dogs and cats undergoing cardiopulmonary resuscitation.

Abstract

OBJECTIVE: To determine whether the partial pressure of end-tidal carbon dioxide (PetCO) could predict return of spontaneous circulation (ROSC) in patients with cardiopulmonary arrest (CPA) undergoing CPR. DESIGN: Prospective observational study. SETTING: Two private specialty referral hospitals. ANIMALS: Thirty-five client-owned dogs and cats in CPA in which CPR was performed and pertinent data recorded on a purpose-made form. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: PetCOwas recorded at 1-minute intervals during CPR. Hospital, animal, arrest, and outcome variables were also reported in the Utstein style where possible. Twelve animals (7 dogs and 5 cats) achieved ROSC; 4 of these (2 dogs and 2 cats) had sustained ROSC, of which 1 dog was discharged alive. Patients that achieved ROSC had significantly higher initial PetCO(P = 0.0083), peak PetCO(P < 0.0001), average PetCO(P < 0.0001), and &#x394;PetCO(difference between last and first recorded PetCO; P = 0.0004) than patients not resuscitated. The PetCOaccurately discriminated between ROSC and failure to achieve ROSC at minutes 3, 4, 5, 6, 7, and 8 of CPR with area under the receiver operating characteristic curve of 0.926, 0.967, 0.938, 0.933, 0.956, and 1.00, respectively. The optimal cutoff PetCOwas 18 mm Hg (2.4 kPa), with a sensitivity of &#x2265;80% and a specificity of &#x2265;95% at minutes 3, 4, 5, 6, and 8, correctly classifying 91-100% of cases. CONCLUSIONS: The results of this small study support previous recommendations to monitor PetCOduring CPR and suggest that PetCOduring CPR may be useful for determining the probability of ROSC. Absolute values and trends of PetCOmay assist clinicians and owners in making decisions for pets with CPA.