Comparison of Shelf-stable and Conventional Resuscitation Products in a Canine Model of Hemorrhagic Shock.

INTRODUCTION: Treatment of severe hemorrhagic shock typically involves hemostatic resuscitation with blood products. However, logistical constraints often hamper the wide distribution of commonly used blood products like whole blood. Shelf-stable blood products and blood substitutes are poised to be able to effectively resuscitate individuals in hemorrhagic shock when more conventional blood products are not readily available. METHODS: Purpose-bred adult dogs (n = 6) were anesthetized, instrumented, and subjected to hemorrhagic shock (MAP <50 mmHg or 40% blood volume loss). Then each dog was resuscitated with one of five resuscitation products: (1) lactated ringers solution and hetastarch (LRS/heta), (2) canine chilled whole blood (CWB), (3) fresh frozen plasma (FFP) and packed red blood cells (pRBC), (4) canine freeze-dried plasma (FDP) and hemoglobin-based oxygen carrier (HBOC), or (5) HBOC/FDP and canine lyophilized platelets (LyoPLT). Each dog was allowed to recover after the hemorrhage resuscitation event and was then subjected to another hemorrhage event and resuscitated with a different product until each dog was resuscitated with each product. RESULTS: At the time when animals were determined to be out of shock as defined by a shock index <1, MAP (mm Hg) values (mean ± standard error) were higher for FFP/pRBC (n = 5, 83.7 ± 4.5) and FDP/HBOC+LyoPLT (n = 4, 87.8. ± 2.1) as compared to WB (n = 4, 66.0 ± 13.1). A transient increase in creatinine was seen in dogs resuscitated with HBOC and FDP. Albumin and base excess increased in dogs resuscitated with HBOC and FDP products compared to LRS/heta and CWB (p < 0.01). CONCLUSION: Combinations of shelf-stable blood products compared favorably to canine CWB for resolution of shock. Further research is needed to ascertain the reliability and efficacy of these shelf-stable combinations of products in other models of hemorrhage that include a component of tissue damage as well as naturally occurring trauma. LEVEL OF EVIDENCE: This is a Therapeutic/Care management study with Level of Evidence IV.

Echocardiography Recording in Awake Miniature Pigs.

Echocardiography uses ultrasonic waves to non-invasively assess cardiac structure and function and is the standard of care for cardiac assessment and monitoring. The miniature pig, or minipig, is increasingly being used as a model of cardiac disease in medical research. Pigs are notoriously difficult to restrain and handle safely, and, therefore, research echocardiography in this species is almost always performed under anesthesia or heavy sedation. Anesthetics and sedatives universally affect cardiovascular function and may cause the depression of cardiac output and blood pressure, increases or decreases in heart rate and systemic vascular resistance, changes in the electrical rhythm, and altered coronary blood flow. Therefore, sedated or anesthetized echocardiography may not accurately depict the progression of cardiac disease in large animal models, thereby limiting the translational value of these important studies. This paper describes a novel device that allows for standing awake echocardiography in minipigs. In addition, training techniques used to teach pigs to tolerate this painless and non-invasive procedure without the need for hemodynamic-altering anesthetics are described. Standing awake echocardiography represents a safe and feasible way to perform the most common cardiac monitoring test in minipigs for cardiovascular research.

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

OBJECTIVE: To determine whether the partial pressure of end-tidal carbon dioxide (PetCO2 ) 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: PetCO2 was 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 PetCO2 (P = 0.0083), peak PetCO2 (P < 0.0001), average PetCO2 (P < 0.0001), and ΔPetCO2 (difference between last and first recorded PetCO2 ; P = 0.0004) than patients not resuscitated. The PetCO2 accurately 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 PetCO2 was 18 mm Hg (2.4 kPa), with a sensitivity of ≥80% and a specificity of ≥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 PetCO2 during CPR and suggest that PetCO2 during CPR may be useful for determining the probability of ROSC. Absolute values and trends of PetCO2 may assist clinicians and owners in making decisions for pets with CPA.