Osamu Shimoda

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.

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.

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 I 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 as an objective indicator to assess the level of regional anesthesia

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. (Anesth Analg 1998;86:336-40)

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.

Evaluation of the central nervous function in resuscitated comatose patients by multilevel evoked potentials

Multilevel evoked potentials were examined in 17 patients who became comatose after cardiac arrest and resuscitation. In 4 patients, the P1 through N3 components of the somatosensory evoked cerebral potential (SECP) were present altogether within 100 ms after the ischemic insults. They all subsequently regained consciousness, though three of them developed intelligence and motor disturbances to some extent. In 11 patients who regained consciousness, or remained in a vegetative state, the evoked potentials which reflect brainstem functions, such as the auditory evoked brainstem potential, the R1 wave of the orbicularis oculi reflex and the slow positive wave of the somatosensory evoked brainstem potential, were recognized. The somatosensory evoked spinal potential and spinal monosynaptic reflex showed normal appearances in the state of vegetation and even after the determination of brain death. The measures of SECP could be useful in predicting restoration of consciousness.

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.

Complete suppression of paroxysmal nonkinesigenic dyskinesia by globus pallidus internus pallidal stimulation

Stereotactic functional surgery is being explored as potential therapies for medically intractable paroxysmal dyskinesias (PxD). We report on a 59‐year‐old man in whom stimulation of globus pallidus internus produced immediate and sustained relief of paroxysmal non‐kinesigenic dyskinesia secondary to a rotator cuff tears on the left shoulder. Our finding strongly suggests that altered function of neuronal circuits of the basal ganglia underlies the manifestation of PxD.

The Current Perception Thresholds Vary Between Horizontal and 70° 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.

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.