Sevoflurane and nitrous oxide anaesthesia suppresses heart rate variabilities during deliberate hypotension.

BACKGROUND AND OBJECTIVE: Despite the fact that both general anaesthetics and hypotensive drugs influence autonomic nervous activity, no study has yet examined the heart rate variability during deliberate hypotension and general anaesthesia. The aim of this was to clarify the heart rate variability changes during deliberate hypotension under sevoflurane-nitrous oxide anaesthesia. METHODS: Autonomic nervous system activity in patients (n=45) subjected to deliberate hypotension during sevoflurane in nitrous oxide and oxygen anaesthesia was investigated by a heart rate variability measurement. Three different types of hypotensive drugs, a calcium channel antagonist (nicardipine), a nitric oxide donor (nitroglycerin) and a vasodilatory prostaglandin (alprostadil), were used to induce hypotension. RESULTS: In all groups, low frequency power (sympathetic and parasympathetic indicator) and the ratio of low frequency to high frequency power (the LF/HF ratio, sympathetic indicator) were suppressed by induction of anaesthesia. In the control group, preanaesthesia low frequency power was 195 +/- 139 ms(2), the LF/HF ratio 10.3 +/- 5.7, during anaesthesia 5 +/- 9 ms(2), 0.6 +/- 0.8, respectively, P=0.0093, 0.0034, whereas high frequency power (parasympathetic indicator) was not significantly changed. In those patients receiving nicardipine or nitroglycerin during anaesthesia, these variables did not differ significantly from those in the control group. During prostaglandin E1 infusion, high frequency power was higher compared with the values in the other groups (17 +/- 12 ms(2) in the prostaglandin group, 7 +/- 6 ms(2) in the nicardipine group, 6 +/- 5 ms(2) in the nitroglycerin group and 6 +/- 4 ms(2) in the control group, respectively, P=0.0326, 0.0251, 0.0197). CONCLUSIONS: Sevoflurane in nitrous oxide and oxygen anaesthesia reduces sympathetic autonomic activity considerably, and the expected increases caused by hypotensive agents that occur in awake volunteers were not seen.

The combination of a fiberoptic stylet and a McCoy laryngoscope facilitates tracheal intubation in difficult airway cases.

PURPOSE: Fiberoptic stylets are considered useful for difficult airway management. In the present study, we assessed the usefulness of a fiberoptic stylet when the stylet was used with a Macintosh or a McCoy laryngoscope. METHODS: Twenty-four patients, whose airways were graded as Cormack grade III, were studied. We compared the times required for tracheal intubation when the fiberoptic stylet was used with a Macintosh direct laryngoscope and when it was used with a McCoy laryngoscope. Cormack grade III was subdivided into IIIa (with distance between the epiglottis and the posterior wall of the pharynx) and IIIb (with no distance between the epiglottis and the posterior wall of the pharynx), according to the view of the vocal cords by the laryngoscope. RESULTS: The intubation time in grade IIIb patients, who were intubated by the concurrent use of the fiberoptic stylet and the McCoy laryngoscope (28 +/- 4 s), was not significantly different from that in grade IIIa patients (28 +/- 10 s). The intubation time in grade IIIb patients, who were intubated by the concurrent use of the fiberoptic stylet and the Macintosh laryngoscope (52 +/- 8 s), was significantly longer than that in grades IIIa (28 +/- 10 s; P < 0.01) or IIIb with the McCoy laryngoscope (28 +/- 4 s; P < 0.01). CONCLUSION: The combination of a new handy fiberoptic stylet and a McCoy laryngoscope facilitated tracheal intubation of patients whose airway had no distance between the epiglottis and the posterior wall of the pharynx in laryngoscopic vocal cord view.

Use of a fibreoptic stylet to visually evaluate tracheal intubation technique.

To compare the tracheal intubation by novices with that of instructors, we videotaped the view obtained through a fibreoptic stylet during standard tracheal intubations with a Macintosh direct laryngoscope. The duration of visualization of the vocal cords was longer during intubation by instructors than during trainee attempts. The tracheal tube contact (with pharyngeal wall) time duration was higher during intubation attempts by trainees than instructors. The quality of the image of the vocal cords through the stylet was related to these video-view parameters. Our results demonstrated that visualization of the vocal cords by direct laryngoscope and manipulation of the tracheal tube in the oral cavity were different between anaesthesia trainees and instructors, and suggested that visually monitoring the tracheal intubation procedure through a fibreoptic stylet might be useful for the education of anaesthesia trainees.

Vecuronium dose requirement and pupillary response in a patient with olivopontocerebellar atrophy (OPCA).

PURPOSE: Olivopontocerebellar atrophy (OPCA), a variant of spinocerebellar degeneration (Shy-Drager syndrome), is a systemic degenerative disorder affecting the neurons of multiple nuclei. We investigated the sensitivity to vecuronium and the pupillary responses to various stresses in a patient with OPCA. CLINICAL FEATURES: A 65-yr-old woman with a six-month history of OPCA underwent a left upper lobectomy for lung cancer under propofol-N2O anaesthesia. She had symptoms of dysarthria, bulbar palsy, cerebellar ataxia, Parkinsonism, myosis, pyramidal signs and muscular atrophy of the distal extremities. A cumulative dose-response curve for vecuronium was constructed, and pupillary changes in response to various noxious stimuli were evaluated with concomitant recording of the Spectral-Edge-Frequency 90% (SEF90; the frequency below which 90 percent of the EEG power is located). The dose-response curve for vecuronium and the estimated ED50 value (the 50% blocking dose of vecuronium) in this patient with OPCA were almost identical with those of five ASA I-II patients (27 micrograms.kg-1 vs 31 micrograms.kg-1). The pupil size and the SEF90 did not change after tracheal intubation or surgical stimulation in this patient, while in the control subjects (n = 3), these measures increased in response to both stresses. CONCLUSIONS: The absence of pupillary and SEF90 responses to noxious stimuli suggests a sensitivity to propofol and/or central autonomic dysfunction in patients with OPCA. Although the dose requirement of vecuronium in this patient was similar to that of the control patients, the effects of neuromuscular blockers may vary depending on the severity of muscle atrophy.

Change in plasma endotoxin titres and endotoxin neutralizing activity in the perioperative period.

PURPOSE: To elucidate whether endotoxaemia detected during major surgery was a specific or non-specific reaction. METHODS: Prospective clinical study in the operating theatre and multidisciplinary intensive care unit in a university hospital. A series of plasma samples was obtained from 21 patients, including eight after cardiopulmonary bypass (CPB), until 48 hr after surgery. The endotoxin titres in these samples were compared by the two chromogenic limulus amebocyte lysate (LAL) assays; one is factor G containing and the other factor G-free, endotoxin-specific test. The endotoxin neutralizing activity of the plasma was determined by adding the endotoxin to the plasma (1,000 pg.ml-1), and by assaying how much the potency of the endotoxin to activate LAL was lost during incubation for 120 min at 37 degrees C. RESULTS: Although endotoxin titres measured using the test including factor G showed a marked elevation during and after surgery, which were 3 +/- 5 (4 +/- 10), 14 +/- 13 (20 +/- 17**), 133 +/- 13* (46 +/- 29*), 89 +/- 72* (48 +/- 35*), 62 +/- 40** (37 +/- 29*), 50 +/- 54 (39 +/- 36) pg.ml-1 in patients with CPB (without CPB), mean +/- SD, at 0, 3, 6, 9, 24, and 48 hr after start of surgery (*P < 0.01, **P < 0.05 compared with 0 hr), those measured by the endotoxin-specific test did not show any changes. Plasma neutralized 95% of endotoxin potency after five minutes incubation at 37 degrees C. CONCLUSION: Using an endotoxin-specific assay, endotoxin could not be detected in the blood stream during or after major surgery.

[The changes of central nervous synapses after transient cerebral ischemia].

Changes in drebrin, MAP2 (postsynaptic marker) and synaptophysin (presynaptic marker) in rat brains were examined after 20 min of transient cerebral ischemia. Immunoreactivity for drebrin and MAP2 in hippocampus CA1 area decreased 7 days after ischemia. The immunoreactivity for debrin in stratum lucidum of hippocampus CA3 area increased 7 days after ischemia. Sodium dodecyl sulfate gel electrophoresis and immunoblot procedures using an antibody to drebrin, MAP2 and synaptophysin were carried out. The levels of drebrin and MAP2 in hippocampus decreased significantly 4 hours and 7 days after recirculation. In contrast, the level of synaptophysin was unchanged. The levels of each protein in cerebral cortex showed no significant changes. The changes after ischemia seemed to occur at the same time both in the dendritic spines and in their shafts, and the increase of the immunoreactivity for drebrin in CA3 might suggest the change of cytoskeletal protein synthesis in survived neurons.

[Intravenous pirenzepine reduces salivary secretion rapidly].

We evaluated the effects of pirenzepine on salivary secretion and heart rate, comparing them with those after atropine. Forty-two patients for gynecological operations were divided into three groups. P, A and C groups received pirenzepine 10 mg, atropine 0.5 mg and saline 1 ml intravenously 4 min before induction. Salivary secretion was aspirated at 30, 60 and 120 min after induction. Heart rate was recorded at 1, 30, 60 and 120 min after injection. In P and A groups, salivary secretion decreased significantly, but there was no significant difference between them. In A group, heart rate increased at 1, 30 and 60 min after injection, but at 120 min there was no difference among three groups. We conclude that intravenous pirenzepine as well as atropine reduces salivary secretion, but it does not increase heart rate as atropine.

[Evaluation of buprenorphine hydrochloride suppositories for postoperative pain relief].

An analgesic is often administered upon the occurrence of pain following surgery. Buprenorphine hydrochloride suppository (0.2 mg) was given immediately postoperatively to patients who had undergone surgery under general anesthesia. Post-operative pain has been observed after 782 +/- 41 minutes (n = 148, mean +/- SE) in the patients with suppository and 127 +/- 18 minutes (n = 57) in the control group (P less than 0.01). Analgesics were given to 68% of the control group within 2 hours, while it was given to 14% of the study group. Further 57% of the latter did not complain of any pain after 20 hours. The pharmacokinetics of buprenorphine was studied in 7 patients. Intrarectal administration of 0.2 mg buprenorphine suppository just after surgery had a sufficient analgesic action and did not induce any adverse reactions of any clinical importance.