Influence of experimentally elevated blood viscosity on the auditory nerve-brainstem evoked response and threshold.

Blood viscosity, due to its effect on blood flow, is one of the determinants of oxygen delivery. Therefore the influence of elevated blood viscosity on hearing was studied in rats using the auditory brainstem response (ABR) threshold, wave 1 latency, brainstem transmission time (BTT) and wave 1/4 amplitude ratio. Whole blood viscosity (WBV) was elevated by 15-21% in two different ways: elevating the hematocrit (Polycythemia) by acclimation in a hypobaric chamber, or elevating the plasma viscosity by infusing a solution of Polyvinylpyrrolidone-360 (PVP). ABR was recorded before and 24 h after the blood viscosity was elevated, so that each rat served as its own control. Paired t-tests showed that there was no statistically significant difference in the ABR parameters in each of the groups as a consequence of blood viscosity elevation. In conclusion, the elevation of WBV to this degree for this duration, using two different techniques had no effect either on the function of the auditory nerve and the more peripheral sites, or on the central auditory pathway as studied by ABR.

"Conscious sedation" for laparoscopy.

End-tidal pCO2, mean arterial blood pressure, heart rate and respiratory rate changes during diagnostic gynecological laparoscopy were studied in 30 healthy women by the technique of "conscious sedation" combined with local anesthesia of the skin and peritoneum. No significant hypercarbia or hypoxia was noted. Patients were discharged from hospital within 6 to 8 h of the laparoscopy; all noted their full satisfaction with this method of anesthesia. "Conscious sedation" appears to be a safe and efficient method for short diagnosis laparoscopies in young, nonobese, otherwise healthy patients in whom full general anesthesia is refused or considered inadvisable.

The effect of ketamine on the functional residual capacity in young children.

The effect of ketamine on the functional residual capacity (FRC) was measured in nine ASA class I children prior to elective surgery. FRC was determined by the closed-circuit helium dilution method on the day prior to surgery in the awake state and also following induction of anesthesia on the day of the operation. Anesthesia consisted of ketamine by continuous intravenous infusion following preanesthetic sedation with atropine and triclofos or flunitrazepam. There were no significant differences in FRC between the measurements in the awake state and anesthetized (392 +/- 43 SEM ml, and 411 +/- 53 SEM ml, respectively), and the authors conclude that ketamine does not affect resting lung volume in young children.

Oral flunitrazepam in the prevention of local anaesthetic-induced convulsions in mice.

The present study determined whether oral flunitrazepam was effective reducing CNS toxicity of lidocaine and bupivacaine. Pretreatment of mice with flunitrazepam, 0.065-0.25 mg X kg-1, significantly reduced or prevented convulsions and mortality induced by lidocaine 106 and 209 mg X kg-1 or bupivacaine 58 and 90 mg X kg-1 injected intraperitoneally. The doses of flunitrazepam used did not cause measurable sedation in mice. The efficacy of oral flunitrazepam in preventing local anaesthetic-induced convulsions is similar to that previously reported by intraperitoneal or intramuscular injections in mice. Flunitrazepam could be useful for oral premedication of patients before regional anaesthesia.

Common bile duct pressure in dogs after opiate injection--epidural versus intravenous route.

The effect on the common bile duct pressure of epidurally injected morphine and fentanyl, was compared with that of intravenous injections of the same drugs in 12 mongrel dogs. Intravenous injection of morphine (0.1 mg X kg-1) or fentanyl (0.01 mg X kg-1) significantly elevated the common bile duct pressure from 10.48 +/- 0.37 to 21.68 +/- 0.33 cm H2O and from 9.66 +/- 0.33 to 14.14 +/- 0.21 cm H2O respectively. These increases occurred within 4-15 minutes after injection and lasted for about 2-3 hours. When the narcotics in identical dosages were injected epidurally, the common bile duct pressures were unchanged during the four hours of investigation. Further studies are planned to determine whether this beneficial effect of epidural narcotics applies also in the human clinical situation.

Capnography in the early diagnosis of carbon dioxide embolism during laparoscopy.

Venous embolism of carbon dioxide occurred during elective diagnostic laparoscopy in a healthy adult female. The diagnosis of gas embolism was made on the basis of the sudden abrupt onset of systolic and diastolic murmurs. The continuously recorded end-tidal carbon dioxide concentration (FETCO2) increased abruptly from 3.8 to 4.2 per cent and then slowly decreased to 4.0 per cent over the subsequent 30 seconds. CO2 insufflation was terminated immediately following the establishment of the diagnosis. The patient recovered uneventfully. A transient but rapid rise in FETCO2 is suggested as a useful early sign of venous CO2 embolism during laparoscopy.

Neonatal outcome in cesarean section under general anesthesia, related to gestational age, induction-delivery and uterus-delivery intervals.

Neonatal outcome after cesarean section under general anesthesia was studied in 568 women in whom no prior signs of fetal distress were evident. Low Apgar 1-minute scores were not related to induction-delivery and/or to uterus-delivery intervals, which were all within the accepted safe limits, but were related to the gestational age. Thus, Apgar scores less than 7 were found in 62% of newborns whose gestational age was less than 35 weeks, but in only 17% of those greater than or equal to 35 weeks. The importance of gestational age, in addition to the induction-delivery and uterus-delivery intervals, is discussed in relation to neonatal outcome following cesarean section.

A comparison of flunitrazepam and diazepam in the prevention of local anesthetic-induced convulsions.

The anticonvulsive effects of equivalent strengths (ED50) of flunitrazepam and diazepam were compared in 60 Sabra mice injected i.p. with median convulsive (CD50) doses of lidocaine or bupivacaine. Convulsions occurred in 40% of those pretreated with diazepam but were completely prevented in those injected with flunitrazepam. Mortality was much higher in those mice pretreated with diazepam, three having died after the administration of lidocaine and four after bupivacaine. With flunitrazepam pretreatment, there were no deaths after lidocaine and only one after bupivacaine. Flunitrazepam protected these mice against local anesthetic-induced convulsions more effectively than did diazepam.

Effect of 24-hour food-and-water deprivation on biochemical variables in blood.

In 38 subjects, 24-h food-and-water deprivation during the Jewish fast day, Tisha b'Av, led to a 2.5-fold increase in plasma free fatty acids and to a doubling of the bilirubin concentration. There were also significant increases in serum sodium, chloride, total proteins, albumin, uric acid, phosphorus and alkaline phosphatase and aspartate aminotransferase activity. Serum glucose and triglycerides decreased in concentration. There were no changes in concentrations of urea, potassium, cholesterol or calcium. The marked increases in free fatty acids might constitute a hazard for those with impaired myocardial function.

Intravenous flunitrazepam in the prevention of the side effects of succinylcholine.

Muscular fasciculations, plasma potassium levels and postoperative muscle pains following succinylcholine injection were studied in 64 patients who had been given either dilute flunitrazepam or sodium thiopental to induce anesthesia. In the 32 patients with flunitrazepam-induced anesthesia, muscle fasciculations were present in only 8 and postoperative muscle pains in 4, while none of the patients had elevated plasma potassium. In the thiopental group, muscle fasciculations and postoperative muscle pains were present in 28 and 22 of the other 32 patients, respectively, while all had significantly elevated plasma potassium levels. Flunitrazepam appears to be a useful alternative anesthesia-induction agent that prevents some of the side effects of succinylcholine without reducing its efficiency.