To compare efficacy and duration of desensitization of oral structures with a lidocaine-bupivacaine mixture administered via a lateral percutaneous or modified infraorbital approach.
6 healthy adult hound-type female dogs.
In this crossover study, dogs were randomized for side (left or right) and maxillary nerve approach (lateral percutaneous or infraorbital), with a 2-week washout period. Dogs were anesthetized, and a 2-mL mixture of 2% lidocaine and 0.5% bupivacaine (50:50 [vol/vol]) was administered with a 22-gauge, 4.5-cm-long catheter inserted through the infraorbital canal (infraorbital approach) or with a shielded stimulating needle to the maxillary nerve (percutaneous approach). Reflex-evoked motor potentials were measured for the maxillary canine tooth, fourth premolar tooth, second molar tooth, and hard palate mucosa ipsilateral to the injected mixture and for the contralateral maxillary canine tooth (control) at three 10-minute intervals before injection (baseline) and at predetermined times after injection for up to 6.7 hours. For each oral structure, the proportion of dogs with desensitization (efficacy) and time to onset and duration of desensitization were compared between approaches.
The proportion of dogs with successful nerve blockade did not significantly differ between infraorbital and percutaneous approaches and among the 4 oral structures. Time to onset of desensitization did not differ between approaches, but duration was significantly longer with the infraorbital approach.
CONCLUSIONS AND CLINICAL RELEVANCE
A modified infraorbital approach with the lidocaine-bupivacaine mixture had similar effects to a lateral percutaneous approach but provided a longer duration of desensitization. Neither approach was universally successful at desensitizing all oral structures.
To compare the efficacy and duration of desensitization of oral structures following injection of various volumes of lidocaine-bupivacaine via an infraorbital approach in dogs.
6 healthy adult hound-type dogs.
In a randomized crossover study, each dog received 1, 2, and 3 mL of a 2% lidocaine-0.5% bupivacaine mixture (50:50 vol/vol) injected within and near the caudal aspect of the infraorbital canal with a 14-day washout period between treatments. Dogs were anesthetized, and each treatment was administered through a 22-gauge, 4.5-cm-long catheter, which was fully inserted through and then withdrawn 2 cm to the caudal aspect of the infraorbital canal. The reflex-evoked motor potential was measured for the maxillary canine tooth (MC), fourth premolar tooth (MPM4), second molar tooth (MM2), and hard palate mucosa ipsilateral to the injected treatment and for the contralateral MC (control) at predetermined times before and for 6 hours after treatment administration or until the block was no longer effective. For each oral structure, the proportion of dogs with desensitization (efficacy) and time to onset and duration of desensitization were compared among the 3 treatments (injectate volumes).
Treatment was not associated with efficacy, time to onset, or duration of desensitization. Regardless of treatment, MC and MPM4 were more frequently desensitized and mean durations of desensitization for MC and MPM4 were longer, compared with those for MM2 and the hard palate.
CONCLUSIONS AND CLINICAL RELEVANCE
The volume of local anesthetic used for an infraorbital nerve block had no effect on block efficacy or duration.
Objective—To compare effects of isoflurane and sevoflurane on intracranial pressure and cardiovascular variables at 1.0, 1.5, and 2.0 times the minimum alveolar concentration (MAC) in mechanically ventilated normocapnic dogs.
Animals—6 healthy male Beagles.
Procedures—The individual MAC was determined for each agent with an electrical stimulus. After a minimum of 1 week, anesthetic induction by use of a mask with one of the inhalation anesthetics selected randomly was followed by mechanical ventilation and instrumentation for measurement of intracranial pressure and cardiovascular variables. Heart rate; systolic, mean, and diastolic arterial blood pressures; central venous pressure; mean pulmonary arterial pressure; pulmonary artery occlusion pressure; cardiac output; intracranial pressure (ICP); core body temperature; end-tidal inhalation anesthetic and carbon dioxide concentration; and arterial blood gas values were measured after attaining equilibrium at 1.0, 1.5, and 2.0 MAC of each inhalation anesthetic. Cardiac index, systemic vascular resistance, pulmonary vascular resistance, and cerebral perfusion pressure (CPP) were calculated.
Results—Mean ICP did not differ within and between anesthetics at any MAC. Compared with equipotent concentrations of isoflurane, the CPP and mean values for systolic, mean, and diastolic arterial blood pressures were increased at 2.0 MAC for sevoflurane, whereas mean values for mean and diastolic arterial blood pressures and systemic vascular resistance were increased at 1.5 MAC for sevoflurane.
Conclusions and Clinical Relevance—Although ICP was similar in healthy normocapnic dogs, CPP was better maintained during 2.0 MAC for sevoflurane, compared with isoflurane.