An experimental model to study intracranial hypertension-induced vomiting in conscious dogs.

An experimental model to study vomiting due to acute increases in intracranial pressure (ICP) was standardized in dogs. Chronic lateral cerebral ventricle cannulated animals were partially restrained in an observation chamber. The cannula was connected to a buffered saline pressure head which could be adjusted to the required height with the help of a pulley system to attain the desired intracranial pressure. In separate sets of experiments the ICP was raised and maintained at 20, 40, 60 and 80 mmHg for 30 min. The incidence of vomiting and/or retching was observed and the vomiting/retching score (V/R score) was calculated to quantify the severity. The V/R score increased with the level of ICP, maximum being at ICP 80 mmHg. At this level, the effect of pretreatment with propranolol, prazosin and ondansetron was studied. Prazosin and propranolol treatment reduced the vomiting/retching score, while ondansetron failed to do so. This model can be used for evaluating therapeutic interventions for elevated ICP-induced vomiting.