Reflex responses to insertion of the intubating laryngeal mask airway, intubation and removal of the ILMA.

We studied 21 patients (ASA 1 or 2) to investigate the skin vasomotor reflex (SVmR) and haemodynamic responses to insertion of an intubating laryngeal mask airway (ILMA), tracheal intubation using the ILMA and removal of the ILMA. Anaesthesia was induced with fentanyl, midazolam, vecuronium and nitrous oxide. A size 4 ILMA was inserted using the standard technique, and a silicone reinforced tracheal tube (7.5 mm, ID) was passed through it. After confirming successful intubation, the ILMA was removed using the stabilizing rod. The three procedures were performed at approximately one-minute intervals. Insertion of the ILMA, intubation and removal of the ILMA all significantly reduced the skin blood flow on the ring finger in all patients. The mean amplitudes of the SVmR were 0.46 (SD 0.29), 0.54 (0.32) and 0.68 (0.21) respectively. The magnitude of the SVmR and the haemodynamic changes induced by removal of the ILMA were significantly larger than those accompanying the other two procedures. Use of the ILMA for intubation and removal of the ILMA produces three stimuli and the removal of the ILMA produces the greatest response.

[Anesthetic management of a patient with pheochromocytoma and cerebral ischemic attacks].

A 15-year-old girl with history of two cerebral ischemic attacks possibly caused by cerebral vascular spasm was diagnosed as having a pheochromocytoma, and was scheduled for laparoscopic removal of the adrenal tumor. Epidural catheterization was performed at Th 12/L 1. General anesthesia was induced with thiamylal and vecuronium, and maintained with nitrous oxide-oxygen-isoflurane and continuous epidural infusion of 1.5% lidocaine. Phentolamine and thiamylal were continuously administrated into the vein. While operating on the tumor, abnormal hypertension did not occur. Just after removal of the tumor, the systolic blood pressure fell to 50-70 mmHg. The hypotension continued for about 75 min, despite administration of dopamine, norepinephrine and epinephrine. After the emergence from anesthesia, the blood pressure recovered to normal level. No neurocerebral abnormality was found. In patients like this one, we have to prevent cerebral vascular spasm and cerebral infarction caused by excessive secretion of catecholamines.

[A case of high dose administration of propofol].

A 34 year-old-man was scheduled for clipping and bypass surgery of dissecting aneurysm of the right vertebral artery. He previously had an episode suggesting malignant hyperthermia susceptibility during anesthesia managed with suxamethonium and isoflurane. Before the present operation, oral dantrolene 200 mg was administered. Anesthesia was induced with 120 mg of propofol and maintained with 10-6 mg.kg-1.hr-1 of propofol and 60 micrograms.hr-1 of fentanyl for 24 hours. Total dose of propofol amounted to 9,900 mg. Because propofol is formulated as a 10% oil in water emulsion, its high dose administration could alter serum lipid concentrations. However postoperative triglyceride and cholesterol concentrations remained within normal ranges in our case.

The current perception thresholds vary between horizontal and 70 degrees tilt-up positions.

UNLABELLED: We investigated the influence of posture on current perception threshold (CPT). The subjects consisted of 20 healthy male volunteers (23-31 yr old). At both the horizontal and the 70 degrees tilt-up position (TUP), the CPTs (5, 250, and 2000 Hz) of the middle finger were determined by using the Neurometer CPT/C (Neuropteran, Baltimore, MD). Autonomic nervous activities were evaluated by heart rate variability (HRV) analysis and spontaneous baroreflex sensitivity analysis at the two postures previously mentioned. The three CPTs at the 70 degrees TUP were significantly lower than those at the horizontal posture (5 Hz, P < 0.05; 250 Hz, P < 0.001; 2000 Hz, P < 0.05). The changes in HRV and spontaneous baroreflex sensitivity at the 70 degrees TUP indicated decreasing parasympathetic tone. The CPTs of 5 and 250 Hz were significantly correlated with mean systolic blood pressure at the 70 degrees TUP. The CPT of 2000 Hz was significantly correlated with the 0.15-0.4 Hz component in HRV at both postures. The regression analysis of the difference of 5 Hz CPT with that of the mean systolic blood pressure showed a significant correlation (P < 0.001). To evaluate the clinical course of peripheral nerve disorders, the comparison of CPTs measured during the same posture is important. This suggests that CPTs must be measured at the horizontal posture. IMPLICATIONS: Current perception thresholds at the 70 degrees tilt-up posture were significantly lower than those at the horizontal posture. When the compensatory mechanism for preserving blood pressure was emphasized, the current perception thresholds would have a relational connection to mean systolic blood pressure, similar to the concept of hypertension-induced hypoalgesia.

Magnitude of skin vasomotor reflex represents the intensity of nociception under general anesthesia.

Because nociceptive stimuli induce the skin vasomotor reflex (SVmR), the assessment of the SVmR would be a useful indicator to represent nociception. We examined 39 adult patients for the relationship between the magnitude of the SVmR and the intensity of nociceptive stimulus that induced the SVmR. Under oxygen-nitrous oxide (50%) and sevoflurane anesthesia, the SVmR was induced by an electrical impulse to the ulnar nerve and detected by a laser Doppler flowmeter. Study 1: under the end-tidal concentrations of sevoflurane at 1.2% (n = 10), 1.7% (n = 9) or 2.2% (n = 10), the SVmR was tested by a 2-s, 50-Hz tetanic electrical impulse with a current intensity changing (40, 50 or 60 mA) in a randomized order. Study 2: under the end-tidal concentration of sevoflurane at 1.7% (n = 10), the SVmR testing was performed with a 50-mA, 50-Hz tetanic electrical impulse with the current duration changing (2, 3 or 4 s) in a randomized order. The studies demonstrated significant correlations of (1) the current intensity which induces the skin vasomotor reflex (SVmR) vs. the magnitude of the SVmR under the three different anesthesia depths, (2) the anesthesia depth vs. the magnitude of the SVmR (inverse proportion) under the same current intensity and (3) the duration of electrostimulation vs. the magnitude of the SVmR. Thus, the SVmR could be helpful for the objective assessment of nociception and anti-nociceptive effects in individual cases.

[Anesthetic management of a patient with the allergic granulomatous angitis (Churg-Strauss syndrome)].

We gave anesthesia 4 times to a patient (19-year-old female) with allergic granulomatous angitis (AGA). She had asthma, myopathy and detrimental side effect in her eyes of steroid therapy for AGA. Two of the 4 operations were emergency laparotomy for peritonitis due to colon perforation, and the other 2 operations were elective eye surgeries. General anesthesia was induced with thiamylal (1st operation) or midazolam (2nd-4th operation). Intraoperative anesthesia was maintained with N2O-O2-isoflurane combined with thoracic epidural anesthesia (1st operation) or N2O-O2-sevoflurane (2nd-4th operation). Asthmatic attack, which AGA accompanies frequently, did not occur during these anesthetic managements. The steroid therapy, which is a fundamental means to control the allergic syndrome, might suppress asthma. However, asthmatic attack and systemic vasculitis should be kept in mind in anesthetic management of AGA.

Assessing the level of regional blockade under general anesthesia using the skin vasomotor reflex test.

UNLABELLED: We investigated whether skin vasomotor reflex (SVmR) testing can be used to assess the sensory blockade level under light general anesthesia. In 15 patients scheduled for abdominal gynecological surgery, the SVmR was tested under inhaled isoflurane or sevoflurane (0.5%-0.6%) with nitrous oxide (50%). Seven minutes after the epidural injection (5-10 mL of 2% lidocaine), a tetanic electrical stimulus (20 mA, 2 s) was applied to the skin and repeated sequentially from the L3 dermatome in the cephalad direction. Changes in the laser Doppler skin blood flow on the index finger tip were assessed for the SVmR. If there was a positive response, SVmR testing was discontinued. The relationship between the uppermost dermatome of the negative SVmR response and the intraoperative effectiveness of the epidural block was determined. In 11 patients, we confirmed a clear boundary of skin dermatome by the SVmR test. The uppermost dermatome of the negative SVmR response at higher than the T7 level was necessary to maintain the combined epidural and light general anesthesia for the transabdominal gynecological surgery (P = 0.002). We conclude that SVmR testing is useful in estimating the blockade level of regional anesthesia under light general anesthesia. IMPLICATIONS: Considering "preemptive analgesia," a complete sensory blockade should be established before a skin incision. In 11 of 15 patients under epidural/ general anesthesia, we confirmed a clear dermatome boundary using the skin vasomotor reflex test. This test could be an indicator for estimating the sensory blockade level of patients under general anesthesia.

Skin vasomotor reflex as an objective indicator to assess the level of regional anesthesia.

UNLABELLED: We examined whether the absence of a skin vasomotor reflex (SVmR), which represents a sympathetic vasoconstrictive response to various stimuli, is an objective indicator of a somatosensory blockade. Skin blood flow was measured by using a laser Doppler flowmeter on the index finger tip. The somatosensory blockade level was determined in 15 patients under subarachnoid anesthesia. A cold stimulus, an ice cube applied to the skin, was repeated sequentially at each dermatome from L3 cephalad. The uppermost dermatome with negative response (the SVmR cold level) was determined, and the SVmR pain level was determined similarly using an electrical impulse (20-mA, 50-Hz, 0.25-ms square wave). The SVmR cold level and the SVmR pain level showed significant correlation with the conventionally assessed cold level (r = 0.83) and the pinprick level (r = 0.96). We conclude that the SVmR is useful to objectively estimate the level of somatosensory block induced by regional anesthesia. IMPLICATIONS: We evaluated the absence of decrease in skin blood flow after various stimuli as an indicator of somatosensory blockade. In patients under subarachnoid anesthesia, the uppermost level with negative response showed significant correlation with the conventionally assessed blockade level. This method is useful for objective assessment of regional anesthesia level.

Skin vasomotor reflex predicts circulatory responses to laryngoscopy and intubation.

BACKGROUND: An evaluation of autonomic reactivity may help to predict circulatory responses to intubation. The relation between the magnitude of the skin vasomotor reflex (SVmR) immediately before laryngoscopy and the circulatory responses to intubation was examined. METHODS: Forty-four adult patients (classified as American Society of Anesthesiologists physical status I or II) were studied. General anesthesia was induced with fentanyl and thiamylal and maintained with nitrous oxide and sevoflurane. The SVmR was evoked by an electrostimulus to the ulnar nerve, and decreases in skin blood flow were detected using a laser-Doppler flowmeter. In study 1, two groups of patients were studied. In the monitored group (n = 14), laryngoscopy was performed when the SVmR amplitude had decreased to less than 0.1. In the control group (n = 15), intubation was performed regardless of changes in the SVmR amplitude. In study 2, after induction, the end-tidal concentration of sevoflurane was maintained at 1 MAC (n = 9) or 1.3 MAC (n = 6) for 5 min. The SVmR was tested by changing the electric intensity. RESULTS: In study 1, the blood pressure and heart rate of the control group increased significantly (P < 0.01) after laryngoscopy. The blood pressure of the monitored group did not increase. The SVmR amplitude and the systolic blood pressure changes showed a significant linear correlation (P < 0.001). In study 2, the relation between the electric intensity and the SVmR amplitude showed a weak but significant correlation (P < 0.01) in the 1 MAC group. CONCLUSION: The evaluation of the SVmR provides useful information for determining the optimal anesthetic depth for laryngoscopy and intubation in individual patients.

Skin vasomotor reflex induced by laryngoscopy: comparison of the McCoy and Macintosh blades.

We studied 22 female patients (ASA I or II) to investigate if laryngoscopy and intubation induced the skin vasomotor reflex (SVmR), and to compare the effects of the McCoy and Macintosh blades on the SVmR. Anaesthesia was induced with fentanyl, midazolam, vecuronium and nitrous oxide. In 11 patients, the vocal cords were seen for 3 s with the McCoy blade. Two minutes later, laryngoscopy was performed with the Macintosh blade and the trachea was intubated. In the other 11 patients, the first and second laryngoscopies, respectively, were performed with the Macintosh and McCoy blades. Laryngoscopy alone and intubation with laryngoscopy significantly reduced skin blood flow in the ring finger of all patients (P < 0.01), indicating that both procedures provoked the SVmR. The magnitude of the SVmR and haemodynamic changes did not differ significantly between the two groups.

Quantitative assessment of the autonomic nervous system activities during atropine-induced bradycardia by heart rate spectral analysis.

Using power spectral analysis of heart rate fluctuation, autonomic nervous system activities in bradycardia appearing in the initial phase of atropine administration were evaluated quantitatively in 16 healthy females. Atropine sulfate (10 micrograms/kg), diluted in 100 ml of 0.9% NaCl solution, was intravenously infused at a rate of 0.5 micrograms/kg per min. Electrocardiograms were sampled for 4 min for later analysis before and 0, 5, 10, 15 and 20 min after initiation of atropine infusion. Powers of low (LFC, 0.05-0.15 Hz) and high-frequency (HFC, 0.15-0.4 Hz) components in the power spectrum of R-R interval variations, and the LFC/HFC ratio were determined at each sampling point. HFC power at 0-4 min increased from 1.11 +/- 0.18 ms2 (mean) of baseline value to 1.37 +/- 0.19 ms2 (P < 0.05). The next 5-9-min value of 1.48 +/- 0.14 ms2 was the maximum, and the amount of atropine infused by 9 min was 4.5 micrograms/kg. The HFC powers following this point decreased. The 20-24-min value after 10 micrograms/kg atropine decreased to 0.21 +/- 0.03 ms2 (P < 0.01), which was lower than the previous 15-19-min value of 0.36 +/- 0.04 ms2 (P < 0.01). The LFC/HFC ratios showed no significant change for the initial 9 min of the atropine infusion. However, these ratios at 15-19 min and 20-24 min were increased from 0.50 +/- 0.04 (mean) of baseline value to 0.75 +/- 0.09 and 0.81 +/- 0.09, respectively (P < 0.01). A transient vagotonic state after atropine administration, followed by the well-known vagolytic state, was quantitatively detected by non-invasive spectral analysis of heart-rate fluctuation.

Attenuation of the vagolytic effect of atropine during high thoracic epidural anesthesia by heart rate fluctuation analysis.

Fifteen surgical patients received an epidural injection of 12 ml of 1.5% lidocaine through a catheter placed at C7-T1, followed by further injection as required. An intravenous bolus of 0.5 mg of atropine sulfate was administered simultaneously with the initial epidural injection. The high-(HFC: 0.15-0.4 Hz) and low-frequency components (LFC: 0.05-0.15 Hz) of the power spectrum of heart rate fluctuation, and the LFC/HFC ratio were calculated. At 30 min after the initial lidocaine and atropine injection, the HFC decreased to 21% of the baseline value and the LFC decreased to 11%. At 90 min, the HFC showed gradual recovery to 69% whereas the LFC remained low (22%). These results indicate that 0.5 mg of intravenous atropine reduces the autonomic imbalance that occurs under high thoracic epidural anesthesia, but its duration is too short to be effective throughout the course of anesthesia.

Effects of neural blockade and general anesthesia on the laser-Doppler skin blood flow waves recorded from the finger or toe.

Effects of neural blockade and general anesthesia on the basic wave (BW) and the reflex wave (RW) among the laser-Doppler (L-D) skin blood flow waves recorded on the finger or toe were studied in 2 volunteers and 42 patients. The BW was continuous, rhythmic and independent of respiratory movements. The RW, which was induced by a deep inspiration or a snapping sound, was a transient marked reduction in blood flow. The BW was almost flattened and the RW was no longer induced at the finger under complete wrist block (n = 2), or under cervical or upper thoracic epidural anesthesia extended caudally over T7 (n = 2). On the other hand, the BW was still detected with reducing frequency and the RW could be provoked with one exception at the finger on the side with a sympathetic ganglion block at the C6 vertebral level (n = 14). The BW and RW at the toe were retained under lumbar subdural anesthesia (n = 6) as well. However, under the combination of lumbar subdural anesthesia and lower thoracic epidural anesthesia extending rostrally over T4 (n = 6), both the BW and the RW disappeared at the toe. In the course of deepening nitrous oxide/enflurane anesthesia (n = 10), the BW gradually reduced in frequency until it was almost flattened, and it became difficult to provoke the RW. L-D flowmetry of the finger or toe could be a useful clinical measure for detecting the presence or absence of sympathetic function controlling cutaneous vasomotion.

Fundamental patterns and characteristics of the laser-Doppler skin blood flow waves recorded from the finger or toe.

Three different components, Basic Wave (BW), Cardiac Wave (CW) and Reflex Wave (RW), among the laser-Doppler (L-D) skin blood flow waves on the finger- or toe-tip, were studied in 32 healthy volunteers. The cycle of the rhythmic BW was 8.1 +/- 1.7.min-1 and was independent of respiratory movements. The BW was synchronous with the baseline fluctuation in the digit-photoplethysmogram. Power spectral analysis of rhythmic fluctuations in the simultaneously recorded R-R interval on ECG, systolic blood pressure, and L-D skin blood flow disclosed that the BW was correspondent with the Mayer wave, i.e., low frequency component. The cycle of the CW was consistent with the heart rate and was superimposed on the BW. The RW was a transient marked reduction in blood flow, which was induced by a deep inspiration or various sensory stimuli. A sympathetic skin response on the palm and a venoconstrictive response on the occluded arm were observed concomitantly with the RW. Good synchronization was observed in each component of the L-D skin flow waves between the fingers and toes. These findings suggest that the BW and the RW on the finger- or toe-tip are predominantly driven by tonic and reflex phasic activities of descending sympathetic outflows via the supraspinal center, respectively.

[Transdermal application of 10% lidocaine-gel for management of pain associated with herpes zoster].

We have developed transdermally applicable 10% lidocaine aqueous gel containing an absorption promoter and applied it for 15 patients suffering from severe pain in acute or subacute phase of herpes zoster. The patients, consisting of 7 males and 8 females with a mean age 58.5 +/- 13.0 (SD) yrs, had skin eruptions of herpes zoster for the past 2 months. Lidocaine-gel was applied locally to the diseased skin with or without an occlusive dressing. In 14 of the 15 patients (93%), a remarkable reduction of pain (below 10% of pretreatment level) was obtained after 9.9 +/- 5.6 (SD) times of lidocaine-gel treatments. There was no adverse systemic reactions or local skin damages. None of them developed post-herpetic neuralgia. The lidocaine-gel treatment appears to be very useful for reduction of pain associated with acute or subacute phase of herpes zoster.

A low frequency, high amplitude rhythmic fluctuation of laser-Doppler skin blood flow after subarachnoid phenol block.

A 51-year-old male with a huge chondrosarcoma received subarachnoid dorsal root blocks with 10% phenol in glycerine to treat severe pain along the left leg. The dermatomes below the Th9 lost all somatic sensation on the left side after the nerve blocks, but the patient was not completely relieved from the pain. Laser-Doppler flowmetry on the toe of the left foot disclosed an increased blood flow and an abnormal fluctuation of the cutaneous capillary blood flow, i.e. a high amplitude rhythmic (HAR) wave with 2.5 to 3 cycles.min-1. The low frequency HAR wave persisted for the subsequent 3 months until a tingling sensation returned to the left leg. It would seem that some travelling roots of the sympathetic nerve were preserved from the chemical neurolysis and the remaining efferent and afferent nerve fibers were responsible for the persisting low frequency HAR wave and pain in the left leg.

Dermal patch anaesthesia: comparison of 10% lignocaine gel with absorption promoter and EMLA cream.

The analgesic effects of transdermally applied 10% lignocaine aquagel containing 3% glycyrrhetinic acid monohemiphthalate disodium (as an absorption enhancer) and EMLA cream were compared on the forearms of 34 adult volunteers in a double-blind fashion. The mean pinprick pain scores (graded by noting the number of painful pinpricks out of five) at 30, 60 and 90 min after application and 30 min after removal of the anaesthetics were 3.3 (0.3) (mean SE), 1.2 (0.3), 0.3 (0.1) and 0.3 (0.1) respectively, in the lignocaine gel group. Corresponding scores were 3.5 (0.3), 1.5 (0.3), 0.7 (0.2) and 0.1 (0.1) respectively, in the EMLA group. Insertion of a 26-gauge needle into the treated skin to a depth of 1 mm at 90 min after application was not painful in 91% of the volunteers in the lignocaine gel group and 88% of those in the EMLA group. There was no significant difference in any of the corresponding pain scores between the two groups.

Three-dimensional analysis of systolic blood pressure and R-R interval: proposal of self-sounding spiral theory.

Having noted the findings that the frequency spectrum of fluctuation in blood pressure resembles that in R-R interval on ECG, and that both fluctuations are continuous time-related changes, we attempted three-dimensional analysis of blood pressure, R-R interval and time. The serial values in systolic arterial pressure and R-R interval which were simultaneously taken in 17 healthy volunteers (24.8 +/- 3.5 years old) were later analyzed using a personal computer. When dots of systolic pressure and R-R interval were plotted in order in a three-dimensional manner, they depicted spiral movements around an imaginary axis. The magnitude and angle of dot movement was then expressed quantitatively, by assuming the movements as a group of vectors. The vectors were uniformly distributed in four quadrants. The directions of the vector's connections were clockwise in about 75%, while their angles showed no particular tendency. Based on these three-dimensional morphological features of fluctuations in blood pressure and R-R interval, we propose a hypothesis called 'self-sounding spiral theory' for a mechanism preserving the cardiovascular homeostasis.