[Mouth opening in relation to the craniocervical position during induction of general anesthesia].

BACKGROUND: Decreased mouth opening and limited neck mobility sometimes make direct laryngoscopy or tracheal intubation difficult and compromise the safety in establishing the airway during induction of general anesthesia. Recent report indicated that mouth opening was related to the craniocervical position in awake subjects. The query about whether the neck position modulate the mouth opening during anesthetic induction under paralyzed condition is not clarified. We hypothesized that the neck extension and the flexion induce changes in inter-incisor distance (IID) during anesthetic induction. METHODS: Thirty relatively young patients for general anesthesia were (male; 20, female; 10) subjected. IID was measured with his/her neck positioned flexed, neutral and extended in the sagittal plane, each at preanesthetic awake period, and during anesthetic induction period. The effect of sniffing position on the mouth opening was also studied. RESULTS: At preanesthetic period, IID (mean +/- SD in mm) at neck flexion (37.4 +/- 7.8) was significantly shorter than both at neutral (44.1 +/- 7.5) and at extension (47.4 +/- 7.0). During induction, significant increase in IID was observed as patients' neck position changed from flexed (31.8 +/- 5.4) to neutral (36.6 +/- 5.4), and extended, (41.7 +/- 8.3). Sniffing position did not affect the mouth opening both at preanesthetic and during anesthetic induction period. CONCLUSIONS: Craniocervical extension may play a desirable role in the airway management with mouth opening widely during anesthetic induction under neuromuscular blockade.

[Evaluation of facial nerve palsy with electrogustometry and stapedial reflex].

BACKGROUND: To clarify the prognosis of facial nerve palsy, electroneuronal tests, including electrogustometry and stapedial reflex, have been utilized. But, the relationship among these tests and patients' prognosis is not clear. METHODS: Sixty five patients with peripheral facial nerve palsy were investigated. Electrogustometry (EG), stapedial reflex (SR) and blink reflex (BR) were performed at the first visit on the consult of facial nerve palsy. The palsy scale (full score is 100 points) was evaluated 8 weeks after the onset, and we defined cure cases if score became over 90 points. The cure ratio was examined on each group of EG positive or negative, SR positive or negative and BR R1 wave positive or negative, respectively. The relationship among these three examinations was also investigated. RESULTS: There were no significant differences between the cure ratio of EG positive and negative groups. However, the cure ratio of SR positive group was significantly larger than that of SR negative group. The cure ratio of BR positive group was 100%, regardless of the result of other two tests. CONCLUSIONS: The present study suggests that SR is a more useful parameter than EG for the evaluation of the prognosis of patients with facial nerve palsy, and the pathological meaning of these 2 tests is different from that of BR.

[Relationship between regional cerebrovascular oxygen saturation and jugular bulb oxygen saturation during carotid endarterectomy].

BACKGROUND: Carotid artery cross-clamping ischemia during carotid endarterectomy (CEA) sometimes causes perioperative neurological deficits. Therefore it is important to asses the cerebral oxygen supply/demand relationship during CEA. The aim of this study is to examine the relationship between two monitoring results in CEA. METHODS: Six patients undergoing elective carotid CEA were studied. Regional cerebrovascular oxygen saturation (rSO2) and jugular bulb oxygen saturation (SjvO2) were measured simultaneously during carotid artery cross-clamping. RESULTS: In 5 patients, rSO2 and SjvO2 changed similarly during carotid artery cross-clamping. In one patient, whose arterial cross flow through the anterior communicating artery was poor, rSO2 markedly decreased after cross-clamping, but SjvO2 was unchanged during the same procedure. CONCLUSIONS: Patients with internal carotid artery stenosis have individually different characteristics in cerebral metabolism and cerebral blood perfusion. Our results suggest that multiple monitoring of cerebral blood flow and oxygen saturation provides helpful information in CEA patients.

[Effect of propofol on visual evoked potentials during neurosurgery].

BACKGROUND: Evoked potentials are used to monitor the central nervous system during neurosurgery and it is well known that they are affected by the depth of anesthesia. Many studies on the evoked potential like somatosensory evoked potential (SEP) and auditory brain stem response (ABR) are reported, but studies on visual evoked potential (VEP) are few. We investigated the influence of the propofol concentration on VEP in neurosurgical patients. METHODS: Seven patients scheduled for neurosurgery, three with cranial aneurysm and four with brain tumor, were studied. Anesthesia was maintained with intravenous propofol using target controlled infusion (TCI). We measured the change of amplitude and latency of VEP at three propofol concentrations (effect site concentrations of 1.5, 2.0 and 3.0 microg x ml(-1)), and also evaluated bispectral index (BIS) at each propofol concentration. RESULTS: Amplitude of VEP at 3.0 microg x ml(-1) propofol concentration decreased significantly compared with the amplitude at 1.5 microg x ml(-1) concentration. No significant change was observed with the latency of VEP. The value of BIS at 3.0 microg x ml(-1) propofol concentration also decreased significantly compared with 2.0 microg x ml(-1) concentration. CONCLUSIONS: Amplitude of VEP is strongly affected by the concentration of propofol. Caution should be taken in evaluating VEP in patients undergoing propofol anesthesia.

[Effects of perfusion pressure on cerebral blood flow and oxygenation during normothermic cardiopulmonary bypass].

BACKGROUND: Central nervous system dysfunction after cardiopulmonary bypass (CPB) is an important cause of morbidity and mortality after cardiac surgery. Perfusion pressure (PP) during CPB could be one of the important determinants of cerebral blood flow (CBF). The objective of the present study was to determine the effect of PP on CBF and cerebral oxgenation during normothermic CPB. METHODS: Twelve adult patients undergoing coronary artery bypass graft surgery were randomly assigned to one of two groups based on PP (High and Low group). Patients in High group received phenylephrine immediately after the onset of CPB to maintain PP between 60 and 80 mmHg. Oxyhemoglobin (O2Hb), deoxyhemoglobin (HHb), tissue oxygenation index (TOI), and oxidized cytochrome aa3 (CtOx) were measured by near-infrared spectroscopy, and internal jugular venous bulb blood oxygen saturation (SjvO2) was measured simultaneously. S-100 beta protein concentrations were also measured before and after CPB. RESULTS: SjvO2 in High group increased significantly during CPB. CtOx in Low group decreased significantly during CPB, whereas TOI was unchanged. Although S-100 beta increased significantly at the end of CPB, there was no difference between the groups. CONCLUSIONS: These results suggest that maintaining high PP is benefical for CBF during normothermic CPB.