Cardiopulmonary effects of a new inspiratory impedance threshold device in acute hemorrhagic shock in dogs.
OBJECTIVE
To compare cardiovascular and respiratory effects of an inspiratory impedance threshold device (ITD) in dogs before and after induction of acute hemorrhagic shock.


METHODS
Prospective experimental randomized study.


METHODS
Eight healthy adult dogs.


METHODS
Dogs were anesthetized and maintained on spontaneous ventilation. Tidal volume (V(T)), systolic, mean and diastolic arterial blood pressure (SAP, MAP, DAP), central venous pressure (CVP), gastric P(CO2) (GBF) as an indicator of gastric perfusion, cardiac index (CI), systemic vascular resistance (SVR), oxygen delivery (DO(2)), and plasma lactate were monitored. To monitor respiratory compliance (RC) and respiratory resistance (ResR), animals were briefly placed on mechanical ventilation. Dogs were studied under 4 different conditions: (1) baseline (euvolemic state) (MAP > 60 mm Hg) with and without the ITD and (2) acute hemorrhagic shock (hypovolemic state) (target MAP of 40 mm Hg) with and without ITD. These 4 conditions were performed during one anesthetic period, allowing time for stabilization of parameters for each condition. Data were analyzed by ANOVA for repeated measure mixed models.


RESULTS
No cardiovascular changes were detected between groups with and without use of ITD during euvolemic states. During acute hemorrhagic hypovolemic state, CI and DO(2) were higher with the ITD (2.9 ± 0.6 L/min/m(2)) and (326.5 ± 86.8 mL/min) compared with no ITD (1.8 ± 0.6 L/min/m(2)) and (191.3 ± 58.1 mL/min), respectively. The use of ITD during hypovolemia also increased SAP and MAP. There was an increase in ResR and decreased RC with the ITD in both euvolemic and hypovolemic states.


CONCLUSIONS
The use of an ITD in dogs during acute hemorrhagic hypovolemic shock improved cardiovascular parameters but had negative effects on RC and ResR.
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610, USA.
Alessio
A
Vigani
Andre C
AC
Shih
Gareth J
GJ
Buckley
Leonel
L
Londoño
Carsten
C
Bandt
D000704:Analysis of Variance; D000818:Animals; D002320:Cardiovascular Physiological Phenomena; D004283:Dog Diseases / Q000628:therapy*; D004285:Dogs; D007022:Hypotension / Q000209:etiology / Q000662:veterinary; D012121:Respiration, Artificial / Q000379:methods / Q000662:veterinary*; D012143:Respiratory Physiological Phenomena; D012771:Shock, Hemorrhagic / Q000628:therapy / Q000662:veterinary*