Anesthesia and analgesia
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Anesthesia and analgesia · May 1998
The effects of age and gender on the optimal premedication dose of intramuscular midazolam.
We conducted a double-blind study on the effects of age and gender on the optimal premedication dose of i.m. midazolam. We randomly divided 100 male and 100 female patients in each of three age groups: A = 20-39 yr, B = 40-59 yr, and C = 60-79 yr (total 600 patients) into five groups according to midazolam dosage: 0.04, 0.06, 0.08, 0.10, and 0.12 mg/kg. Midazolam was injected i.m. with atropine 0.01 mg/kg 15 min before the induction of anesthesia. Blood pressure (BP), heart rate, respiratory rate, oxygen saturation (SpO2), sedation level, tongue root depression, eyelash reflex, and anterograde amnesia were monitored. There were no significant differences between male and female patients in any variables in any age. Decrease of SpO2 and loss of eyelash reflex were seen with midazolam 0.10 mg/kg in Group A, and with 0.08 mg/kg in Group B. In Group C, decreases in BP and SpO2, loss of eyelash reflex, and depression of the tongue root were observed with midazolam 0.06 mg/kg. In conclusion, the optimal doses of i.m. midazolam administered 15 min before the induction of anesthesia in male or female patients were 0.08, 0.06, and 0.04 mg/kg for Groups A, B, and C, respectively. ⋯ Midazolam is the most widely used preoperative anxiolytic drug. Our purpose was to evaluate the optimal dose of i.m. midazolam that would maximize the desired effects and minimize the side effects in a common clinical setting. Results indicate that age, but not gender, should affect the i.m. midazolam dose selected for premedication.
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Anesthesia and analgesia · May 1998
Sterility of anesthetic and resuscitative drug syringes used in the obstetric operating room.
Because of the constant threat of emergent cesarean delivery, anesthetic induction and resuscitation drugs are often drawn into syringes and stored in the obstetric operating room (OR). This study investigated the potential for bacterial and fungal contamination of six drugs (thiopental, succinylcholine, ephedrine, atropine, lidocaine, and oxytocin) often prepared in the obstetric OR. A total of 756 drug syringes were prepared and stored in the obstetric OR for 8 days using normal clinical practices. Starting on Day 0, and subsequently on Days 4 and 8 of the experiment, 42 syringes of each drug were randomly selected from the pool, filtered through a 0.45-microm porosity sterile cellulose filter, and cultured on 5% sheep blood agar. Of the 756 syringes tested, none grew organisms of any type, which indicates a probability of drug sterility of > or = 0.9961 (95% confidence interval [CI]). The data from the cultures performed on syringes on Day 0 indicate a probability of initial contamination of < or = 0.018 (95% CI). This study demonstrates a high probability of sterility in drugs drawn into sterile syringes and stored at room temperature in an OR environment for up to 8 days. ⋯ Drug syringes stored in emergency operating rooms are discarded after 24 h because of possible contamination. We searched for microorganisms in drug syringes stored in the operating room for up to 8 days. No microbes were detected using standard sterility testing techniques. Adopting longer storage periods could result in significant cost savings.
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Anesthesia and analgesia · May 1998
The effect of sevoflurane on spontaneous sympathetic activity, A delta and C somatosympathetic reflexes, and associated hemodynamic changes in dogs.
This study examined the effect of sevoflurane on spontaneous renal sympathetic nerve activity (RSNA), A delta- and C-fiber-mediated somatosympathetic reflexes, and hemodynamic changes in anesthetized dogs. RSNA, and A delta and C reflexes evoked by electrical stimulation of the radial nerve were observed in multifiber recordings of efferent activity in renal sympathetic nerves. Sevoflurane was administered at 1%, 2%, 3%, and 4% end-tidal concentrations for periods of 20 min. The mean A delta reflexes decreased by 20%, 39%, and 54% (P < 0.05 to < 0.01), and the C reflexes decreased by 38%, 62%, and 74% (P < 0.05 to < 0.01) at concentrations of 2%, 3%, and 4%, respectively. The relatively greater effect on C reflexes was significant (P < 0.05) and comparable with the effect of mu-opioids. There was no change in mean RSNA, heart rate (HR), and cardiac output (CO) up to 3% sevoflurane, but these decreased by 36%, 24%, and 13% (P < 0.05), respectively, at 4% sevoflurane. Sevoflurane 1%-4% caused a virtually linear reduction in systemic vascular resistance (SVR) from 7% (P < 0.05) to 44% (P < 0.05), together with a reduction in mean arterial pressure (MAP) that was significant for concentrations greater than 2%. The results indicate that sevoflurane causes a greater depression of C compared with A delta reflexes, and that the reduction in MAP was entirely due to a decrease in SVR up to 3%, whereas at 4% sevoflurane, reductions in sympathetic activity, HR, and CO also contributed its depressor effect. ⋯ The relatively greater depressant effect of sevoflurane on C compared with A delta nociceptive somatosympathetic reflexes is similar to mu-opioids. The hypotensive effect of sevoflurane was significant at 2% concentration, whereas heart rate, cardiac output and sympathetic activity were reduced only at concentrations greater than 3%.