Purpose
In our institution, the majority of vitreoretinal surgeries involve parenteral anesthetics immediately prior to retrobulbar anesthetic blocks, in order to provide the patient with anxiolysis and comfort. In some cases, if the patient becomes apneic after the block, the anesthesia provider intervenes to stimulate the patient to ventilate effectively. The purpose of our study was to investigate which, if any, combination of anesthetics provides adequate analgesia while minimizing the need for airway intervention.
Methods
63 consecutive subjects undergoing vitreoretinal surgery were enrolled in this prospective observational study with no exclusions. Patients were given anesthetic agents determined by the anesthesia provider prior to each retrobulbar block. The need for any airway intervention, including chin lift, jaw thrust, or bag mask ventilation, was recorded. A two- sample t-test was used to compare differences in rates of intervention between patients receiving the two most frequent combinations of anesthetic agents. The odds ratio for receiving an airway intervention between these two groups was calculated.
Results
Patients received one or more of the following medications prior to their retrobulbar blocks: propofol, fentanyl, midazolam, and alfentanil. The two most common anesthetics used were propofol + fentanyl (PF), and alfentanil only (A). Overall, nineteen patients (30%) required an airway intervention. The rate of intervention for each drug combination used is shown below in Table 1. Airway intervention was more likely in the PF group than in the A group (p<0.001). There was no significant difference between these two groups in age, sex, BMI, or ASA status. The odds ratio of receiving intervention in the PF group versus the A group was 41.74.
Conclusions
A significantly higher proportion of patients receiving a combination of propofol and fentanyl (PF), compared to those receiving alfentanil (A), prior to retrobulbar anesthesia required airway intervention. Further analysis is needed to determine the optimal anesthetic combination to minimize apnea and the need for intervention.
Keywords: 464 clinical (human) or epidemiologic studies: risk factor assessment •
548 hypoxia •
762 vitreoretinal surgery