Skin Vasomotor Reflex Research Articles

Sympathetic outflow to skin predicts central autonomic dysfunction in multiple system atrophy.

To find out the physiological method for evaluating the severity of central autonomic dysfunction, we performed detailed evaluation of cutaneous vasomotor neural function in a comparatively large sample of multiple system atrophy (MSA). We evaluated cutaneous vasomotor neural function in 24 MSA patients. Skin sympathetic nerve activity (SSNA) and sympathetic skin response (SSR) and skin blood flow (skin vasomotor reflex [SVR]) were recorded at rest, as well as reflex changes after electrical stimulation. The parameters investigated were SSNA frequency at rest, reflex latency and amplitude of SSNA reflex bursts, absolute decrease and percent reduction of SVR, recovery time, and spontaneous SVR and SSR frequency. There were negative correlations between resting SSNA and disease duration or the SCOPA-AUT score, but these were not significant. SSNA reflex latency displayed significant positive correlations with disease duration and SCOPA-AUT score (p < 0.001 and p < 0.01, respectively). In all five patients who underwent the same examination twice, SSNA reflex latency was significantly longer at the second examination than at the first examination (p < 0.005). A significant positive correlation was identified between recovery time of skin blood flow and SCOPA-AUT score or reflex latency (p < 0.05). Significant correlations were not observed between SCOPA-AUT score or disease duration and other parameters. These results suggest that some MSA patients with a comparatively short duration of disease potentially have impaired thermoregulatory function. Measurement of sympathetic outflow to the skin is potentially a useful tool for predicting the severity of central autonomic dysfunction in MSA.

BS09. Latency of the skin vasomotor reflex of the finger to an electrical stimulus to the median nerve

Introduction An electrical pulse to a sensory or mixed peripheral nerve elicits activation of the skin sympathetic response (SSR) and the latency and the duration of the response can thereby be attained. We reasoned that an electrical stimulus may also activate the sympathetic C fibers to the skin blood vessels of the hand and the latency and duration of the skin vasomotor reflexes (VSRs) could also be obtained. Methods We evaluated 30 healthy subjects aged 20–35 years. The subjects had no history of peripheral or central nervous system disease. A 0.5 ms pulse with an intensity four times the threshold was delivered to the right median nerve at the wrist. The stimulus was given at random every 40–60 s. We gave three stimuli to each subject. We recorded the SSR in the palm of the left hand and the VSRs in the tip of the left index finger. The pulsatile skin blood flow (SBF) was recorded with an infrared photoplethysmograph located at the pad of the right index finger. Results All subjects displayed both a SSR and a VSR. The mean latency of the SSR was 1.3 ± 0.3 s with a mean duration of 5.9 ± 0.6 s. The mean latency of the VSR (first decreased pulse) was 3 ± 0.5 s and the mean duration of the VSR was 9.5 ± 2 s. The VSR had a longer latency and lasted more than the SSR. The decrease in the amplitude of the SBF had a mean or 50 ± 8 per cent of the basal flow. Conclusion The SSR and VSRs reflect sympathetic C fibers traffic to the eccrine sweat glands and the skin microcirculation, respectively. The longer latency of the VSRs, compared to the SSR, may reflect a slower conduction time of the sympathetic C fibers to the skin blood vessels or be the consequence of the physiological properties of the response of the neuro-effector junction of the skin blood vessels. This technique allows a quantitative measurement of the latency and duration of the VSRs and is potentially useful for the study of peripheral and central autonomic disorders.

Pre- and postganglionic vasomotor dysfunction causes distal limb coldness in multiple system atrophy

BackgroundThe detailed pathophysiology of limb coldness in multiple system atrophy (MSA) is unknown. MethodsWe evaluated cutaneous vasomotor neural function in 18 MSA patients with or without limb coldness, and in 20 healthy volunteers as controls. We measured resting skin sympathetic nerve activity (SSNA) and spontaneous changes of the sympathetic skin response (SSR) and skin blood flow (skin vasomotor reflex: SVR), as well as SVR and reflex changes of SSNA after electrical stimulation. The parameters investigated were the SSNA frequency at rest, amplitude of SSNA reflex bursts, absolute decrease and percent reduction of SVR, recovery time, and skin blood flow velocity. ResultsBoth the resting frequency of SSNA and the amplitude of SSNA reflex bursts were significantly lower in the MSA group than the control group (p<0.001 and p<0.05, respectively). There were no significant differences between the two groups with regard to the absolute decrease or percent reduction of SVR volume. The recovery time showed no significant difference between all MSA patients and control groups, but it was significantly prolonged in six MSA patients with limb coldness compared with that in the control group and that in MSA patients without limb coldness (p<0.01). The skin blood flow velocity was significantly slower in the MSA group than in the control group (p<0.001). ConclusionIn MSA patients, limb coldness might occur due to impairments of the peripheral circulation based on prolongation of vasoconstriction and a decrease of skin blood flow velocity secondary to combined pre- and postganglionic skin vasomotor dysfunction.

Skin sympathetic function in complex regional pain syndrome type 1.

Cutaneous sympathetic pathophysiology in complex regional pain syndrome type 1 (CRPS-1) is not yet completely understood. To evaluate cutaneous sympathetic dysfunction in CRPS-1, we evaluated sympathetic sweat response (SSwR) and skin vasomotor reflex (SkVR) in CRPS-1 patients. We studied 10 CRPS-1 patients (age 41 ± 13 years; 5 females and 5 males; disease duration 20 ± 22 months) and 10 healthy subjects (age 44 ± 13 years; 3 females and 7 males). SkVRs and SSwRs to several sympathetic activating procedures were recorded on the palms of the CRPS-1 patients (affected side) and controls (right side). There were no significant differences in the baselines of sweat output and skin blood flow between the CRPS-1 and control groups. SSwR and SkVR amplitudes were significantly lower in the CRPS-1 group than in the control group. There was no significant correlation between disease duration and SSwR or SkVR amplitudes among the patients. The reduced SSwRs and SkVRs in the affected limb of our CRPS-1 patients may reflect underlying damage to the sympathetic postganglionic fibres.

Progression of leprosy neuropathy: a case series study

A need still exists to determine the clinical and neurophysiological characteristics of leprosy neuropathy at distinct times of the disease by different methods that measure the various nerve fiber functions. A prospective clinical study was performed with 10 paucibacillary (PB) and 12 multibacillary (MB) patients evaluated at diagnosis and one year after cessation of multidrug therapy (MDT). Peripheral nerve function was assessed clinically and by means of the sympathetic skin response, skin vasomotor reflex, and nerve conduction study (NCS). At diagnosis, 73% of the total 22 patients had nerve function impairment (NFI). Autonomic function (χ2= 5.5, P= 0.019) and NCS (χ2= 7.765, P= 0.01) were significantly more altered in MB than PB patients. At final evaluation, NFI of the MB patients had worsened, especially among the six who had leprosy reaction. As the NFI of PB patients showed improvement, a significant difference between the two groups (χ2= 12.320, P= 0.001) was observed. A high prevalence of neuropathy was observed in newly diagnosed patients. Associating different tests with a thorough clinical neurological evaluation increases detection rates.

Sudomotor, skin vasomotor, and cardiovascular reflexes in 3 clinical forms of Lewy body disease

To elucidate the differences among dementia with Lewy bodies (DLB), Parkinson disease with dementia (PDD), and Parkinson disease without dementia (PD), with respect to the involvement of the autonomic nervous system, we clinically investigated the cutaneous and cardiovascular autonomic functions in patients with Lewy body disease. We studied 36 patients with Lewy body disorders, including 12 patients with DLB (age, 75.4 +/- 5.9 years), 12 patients with PDD (71.0 +/- 6.8 years), and 12 patients with PD (70.9 +/- 4.2 years), and 12 healthy control subjects (69.9 +/- 5.3 years). Sympathetic sweat response (SSwR) and skin vasomotor reflex (SkVR) on the palm were recorded to estimate the cutaneous sympathetic function, and the head-up tilt test was performed and coefficient of variation of R-R intervals (CV(R-R)) was studied to estimate the cardiovascular function. The patients with DLB, patients with PDD, and patients with PD showed severely reduced SSwR amplitudes, significantly lower than that in the controls. The mean SkVR amplitudes in the patients with DLB and patients with PDD were significantly lower than that in the controls, but not in the patients with PD. The mean decreases in the systolic blood pressure during the head-up tilt test in the patients with DLB and patients with PDD were less than that in the controls. The mean CV(R-R) value was significantly lower in the patients with DLB. Sudomotor function on the palm may be severely affected in Lewy body disorders, while skin vasomotor function and the cardiovascular system may be more severely affected in dementia with Lewy bodies and Parkinson disease with dementia than in Parkinson disease.

Differences in skin sympathetic involvements between two chronic autonomic disorders: Multiple system atrophy and pure autonomic failure

Objective Certain stimuli evoke increased sweat secretion (sympathetic sweat response; SSwR) and reduced skin blood flow (skin vasomotor reflex; SkVR) in the palm/sole. We evaluated SSwR and SkVR in patients with multiple system atrophy (MSA) and pure autonomic failure (PAF). Methods SSwR and SkVR on the palm in response to deep inspiration and mental arithmetic were recorded in 11 MSA patients, 11 PAF patients, and 11 healthy controls. In addition, the head-up tilt test was performed, and the coefficient of variation of R–R intervals (CV R–R) was obtained. Results SSwR amplitudes were significantly lower in the MSA and PAF patients than the controls. SkVR amplitudes in the PAF patients were significantly lower than the controls, but preserved in the MSA patients. In head-up tilt tests, all MSA and PAF patients showed orthostatic hypotension, with similar severity. CV R–R was low in the MSA and PAF patients, but a significant difference was found only between the PAF and control groups. Conclusion In the MSA patients, SkVR was preserved, but SSwR was diminished. In the PAF patients, both SkVR and SSwR were attenuated. The combination of SkVR and SSwR tests may differentiate MSA and PAF.

Measurements of sweat response and skin vasomotor reflex for assessment of autonomic dysfunction in patients with diabetes

Aims Some physical or arousal stimuli induce a rise in sweat secretion (sympathetic sweat response or SSwR) and a reduction in skin blood flow (skin vasomotor reflex or SkVR) to the palm. We recorded SSwRs and SkVRs in diabetic patients and assessed the usefulness of these parameters for evaluating autonomic dysfunction in diabetes. Methods We studied 42 diabetic patients (58±12 years) and 42 normal control subjects (59±11 years). Focal sweat secretion and skin blood flow were measured on the palm by a sudorometer and a Doppler flowmeter, respectively. SSwRs and SkVRs to deep inspiration, mental arithmetic, and isotonic exercise were recorded. SSwR amplitude was measured from baseline to peak, and SkVR amplitude (reduction rate) was calculated as: (blood flow reduction/basal blood flow)×100%. We also conducted head-up tilt tests and R–R interval variation tests (coefficient of variation of R–R intervals or CV R–R). Results The SSwR or SkVR amplitudes in the diabetic group were significantly lower than those in the control group for any stimulus. CV R–R in the diabetic group was significantly less than that in the control group. The diabetic group showed a significantly greater reduction in systolic blood pressure during head-up tilt compared with the control group. In the diabetic group, there were significant correlations in SSwR or SkVR amplitudes versus blood pressure falls during the head-up tilt test, and CV R–R values. Conclusion We believe that SSwR and SkVR are useful indexes for the evaluation of autonomic involvement in diabetic patients.

Sympathetic sudomotor and vasoconstrictive neural function in patients with Parkinson's disease

To evaluate sympathetic sudomotor and vasoconstrictive neural function in Parkinson's disease (PD), we simultaneously recorded sympathetic skin response (SSR) and skin blood flow (SVR; skin vasomotor reflex), as well as skin sympathetic nerve activity (SSNA) measured in peroneal nerves by microneurography, comparing 12 patients with idiopathic PD with 16 healthy controls. Resting SSNA frequency (8.8 ± 4.3 bursts/min) was significantly lower in PD patients than in controls ( p < 0.01). Frequency increases in response to performing mental arithmetic were slightly smaller in PD patients than in controls. PD patients exhibited normal SSNA reflex latencies compared with controls. Although no significant relationship was found between resting SSNA frequency and disease duration or degree of disability, a significantly negative correlation between increases in SSNA with mental arithmetic and PD duration was observed. Occurrence of SSR and SVR following SSNA bursts induced by electrical stimuli was reduced in PD ( p < 0.05). In patients with PD, sympathetic sudomotor and vasoconstrictive neural function was decreased at rest, but SSNA reflex latencies in the legs were nearly normal. Since responses of peripheral target organs may be impaired, both central and peripheral factors may contribute to autonomic symptoms in PD.

Effects of epidural anesthesia with 0.2% and 1% ropivacaine on predicted propofol concentrations and bispectral index values at three clinical end points

Study ObjectiveTo compare the effects of 0.2% epidural ropivacaine and those of 1% epidural ropivacaine on predicted propofol concentrations and bispectral index scores (BISs) at three clinical end points. DesignRandomized double-blind study. SettingUniversity hospital. PatientsThirty-five (35) ASA physical status I and II patients scheduled for elective surgery of the lower abdomen. InterventionsPatients were randomly divided into 2 groups to receive epidurally 8 mL of 0.2% or 1% ropivacaine followed by the same solution at a rate of 6 mL/h. MeasurementsTwenty minutes after starting ropivacaine, a target-controlled infusion of propofol was started to provide a predicted blood concentration of 3 μg/mL; it increased by 0.5 μg/mL every 60 seconds until all 3 clinical end points were reached, as follows: P1, when patients lost consciousness; P2, when patients failed to show pupillary dilation and skin vasomotor reflex to transcutaneous electric stimulation applied to the upper level of loss of cold sensation; and P3, when patients failed to show pupillary dilation and skin vasomotor reflex to transcutaneous electric stimulation applied to C5. Main ResultsThe effective concentration 50 values for both predicted blood and effect-site propofol concentrations were significantly larger in the 0.2% group than in the 1% group at all end points. The BIS at every end point was significantly smaller in the 0.2% group than in the 1% group. ConclusionsDuring combined epidural-propofol anesthesia, unconsciousness and lack of response to noxious stimulation occurred at lower predicted concentrations with 1% epidural ropivacaine than with 0.2% epidural ropivacaine. The results also suggest that the BIS may not be a good indicator when propofol anesthesia is combined with epidural anesthesia.

Skin vasomotor reflex responses in two contrasting groups of autonomic failure

A variety of stimuli such as deep inspiration, isometric exercise and mental arithmetic, result in a transient vasoconstriction,mediated by sympathetic efferent nerves, in the skin of the fingers and toes of healthy controls (Skin Vasomotor Reflex: SkVR). Multiple system atrophy (MSA) and pure autonomic failure (PAF) provide contrasting models of autonomic failure. In MSA the lesion is central and preganglionic, whilst in PAF the lesion site is peripheral and postganglionic. We evaluated the SkVR in response to various stimuli in MSA and PAF, to determine differences in skin vasomotor involvement between these two patient groups. 25 subjects (10 MSA, 7 PAF, 8 healthy controls) were studied. Baseline recordings of skin blood flow were obtained with a laser Doppler probe on the left index finger pulp and forearm. The subject then underwent a variety of stimuli with rest periods in between to reestablish baseline SkBF. These stimuli were: single deep inspiration (inspiratory gasp); mental arithmetic; bilateral leg elevation and cutaneous cold. Healthy control subjects demonstrated marked SkVRs on the finger pulp to each of the stimuli of a magnitude similar to those seen in previous studies, but no SkVRs on the forearm. In MSA SkVRs to inspiratory gasp on the finger pulp were reduced relative to controls. In PAF SkVRs were reduced relative to controls or MSA. The magnitude of SkVR response to gasp and cutaneous cold in PAF was significantly less than in healthy controls. In addition, the magnitude of the response in PAF was significantly less than in MSA for inspiratory gasp. PAF showed a decreased SkVR response to all 4 stimuli, the response being significantly less than controls (for inspiratory gasp and cutaneous cold) or MSA (cutaneous cold inspiratory gasp). The decreased responses in PAF may reflect the extensive postganglionic sympathetic denervation seen in this group. The measurement of SkVR may therefore provide a non-invasive aid to the differentiation of MSA and PAF.

The Effect of Different Physiological Stimuli on Skin Vasomotor Reflexes above and below the Lesion in Human Chronic Spinal Cord Injury

Objective. Spinal cord injury (SCI) results in disruption of descending tonic activation of sympathetic circuits in the spinal cord. The authors determined whether different stimuli that increase sympathetic activity induced cutaneous vasoconstriction (skin vasomotor reflex, SkVR) above and below the level of lesion in subjects with clinically complete SCI. Methods. Baseline skin blood flow (SkBF) and SkVR reduction rate in the pulp of the finger and great toe was measured by laser Doppler probes in chronic complete SCI and in controls. Results. In the finger, baseline SkBF was similar in SCI and controls. The SkVR was elicited by all stimuli in controls but was significantly diminished to gasp, mental arithmetic, tactile stimulation, cutaneous cold, and deep breathing in high SCI compared to controls. In the toe, baseline SkBF was less stable in both controls and SCI. SkVR trends were identified in controls, and responses were not present or greatly reduced in high and low SCI. Conclusions. Measurements of skin vasomotor reflexes to physiological stimuli may be a noninvasive method to evaluate the extent of sympathetic adrenergic pathways in chronic SCI. This is of clinical relevance in monitoring recovery of sympathetic adrenergic function either spontaneously or following repair interventions.

High prevalence of vasomotor reflex impairment in newly diagnosed leprosy patients

Initial nerve damage in leprosy occurs in small myelinated and unmyelinated nerve fibers. Early detection of leprosy in the peripheral nervous system is challenging as extensive nerve damage may take place before clinical signs of leprosy become apparent. In order to determine the prevalence of, and factors associated with, peripheral autonomic nerve dysfunction in newly diagnosed leprosy patients, 76 Brazilian patients were evaluated prior to treatment. Skin vasomotor reflex was tested by means of laser Doppler velocimetry. Blood perfusion and reflex vasoconstriction following an inspiratory gasp were registered on the second and fifth fingers. Vasomotor reflex was impaired in at least one finger in 33/76 (43%) patients. The fifth fingers were more frequently impaired and suffered more frequent bilateral alterations than the second fingers. Multivariate regression analysis showed that leprosy reaction (adjusted odds ratio = 8.11, 95% confidence interval: 1.4-48.2) was associated with overall impaired vasomotor reflex (average of the four fingers). In addition, palmar erythrocyanosis and an abnormal upper limb sensory score were associated with vasomotor reflex impairment in the second fingers, whereas anti-phenolic glycolipid-I antibodies, ulnar somatic neuropathy and a low finger skin temperature were associated with impairment in the fifth fingers. A high prevalence of peripheral autonomic dysfunction as measured by laser Doppler velocimetry was observed in newly diagnosed leprosy patients, which is clinically evident late in the disease. Autonomic nerve lesion was more frequent than somatic lesions and was strongly related to the immune-inflammatory reaction against M. leprae.

Cutaneous sympathetic function and cardiovascular function in patients with progressive supranuclear palsy and Parkinson's disease

Some procedures, such as deep inspiration, increase sweat output (SSwR; sympathetic sweat response) and reduce cutaneous blood flow (SVR; skin vasomotor reflex) on the palm. We investigated SSwR, SVR, and cardiovascular function in 12 patients with progressive supranuclear palsy (PSP), 13 patients with Parkinson's disease (PD), and 9 healthy subjects. In the PSP patients, SSwR was severely diminished, whereas SVR was maintained and cardiovascular function was well preserved. In the PD patients, SSwR was relatively preserved, SVR was maintained, and some patients showed cardiovascular hypofunction. A combination of skin sympathetic and cardiovascular tests may be useful for distinguishing between PD and PSP.

Cutaneous sympathetic function in patients with multiple system atrophy.

Some procedures increase the sweat output (SSwR; sympathetic sweat response) and reduce the cutaneous blood flow (SVR; skin vasomotor reflex) in the hand. We evaluated SSwRs and SVRs to deep inspiration, mental arithmetic, exercise, and tactile stimulation in 40 MSA patients and 15 healthy controls. We also conducted head-up tilt tests and R-R interval variation tests (CV(R-R)). SSwRs were present in all controls, but absent in 19 (47.5 %) of the MSA patients. The mean SSwR amplitudes in the MSA group were significantly lower than those in the control group. SVRs were evoked in all subjects except 3 MSA patients. There were no marked differences in SVR amplitudes between the two groups. Orthostatic hypotension and low CV(R-R) values were seen in 18 (45 %) and 13 (32.5 %) of the MSA patients, respectively. SSwR amplitudes correlated significantly with postural fall in blood pressure and CV(R-R) values in the MSA group. SSwRs were absent in about half of the MSA patients, and the SSwR results correlated with those of the cardiovascular autonomic tests. The SVRs were not severely disturbed in the MSA patients. We considered SSwR a useful index for the detection of autonomic dysfunction in MSA.

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.

Prediction of the haemodynamic response to tracheal intubation: comparison of laser-Doppler skin vasomotor reflex and pulse wave reflex

The laser-Doppler skin vasomotor reflex (SVmR) caused by tetanic stimulation of the ulnar nerve may be a test that can predict the haemodynamic response to tracheal intubation. A decrease in pulse wave amplitude (pulse wave reflex, PWR) may be an alternative index of this response. We compared the abilities of PWR and SVmR to predict the haemodynamic response to tracheal intubation and studied how alfentanil, muscle relaxation, stimulation site and stimulation pattern affected the two reflexes. Anaesthesia was induced and maintained with 2% sevoflurane and 50% nitrous oxide in two groups of 10 ASA status 1 patients. Tetanic stimuli were applied to the flexor muscles of the forearm and the ulnar nerve before and after administration of vecuronium. The change in skin blood flow (laser-Doppler) and pulse wave amplitude (pulse oximetry) after a 5 and 10 s stimulation was measured on the opposite hand. If skin blood flow (laser-Doppler) decreased by more than 10%, a computer-controlled infusion of alfentanil was started and the target plasma concentration was increased in steps until this response was suppressed (< 10%). The trachea was intubated and arterial pressure and heart rate responses were recorded. Plasma alfentanil concentration was measured. When PWR and SVmR were suppressed, the haemodynamic response to tracheal intubation was reduced in 100 and 53% of patients respectively. PWR and SVmR responses decreased with increasing plasma alfentanil concentration. The SVmR response to muscle stimulation was reduced by muscle relaxants. The pulse wave response to both muscle and neural stimulation was reduced by relaxants. The responses to 5 and 10 s stimulations were similar. An absent SVmR does not predict a blunted arterial pressure or heart rate response to tracheal intubation. The PWR may be a better predictor.

Prediction of the haemodynamic response to tracheal intubation: comparison of laser-Doppler skin vasomotor reflex and pulse wave reflex

Prediction of the haemodynamic response to tracheal intubation: comparison of laser-Doppler skin vasomotor reflex and pulse wave reflex

Autonomic function in demyelinating and axonal subtypes of Guillain-Barré syndrome.

To investigate whether or not the pattern and extent of autonomic involvement differ between the two subtypes of Guillain-Barré syndrome (GBS), namely acute inflammatory demyelinating polyneuropathy (AIDP) and acute motor axonal neuropathy (AMAN). Head-up tilt test, R-R interval variation, plasma noradrenaline concentration, skin vasomotor reflex (SVR) and sympathetic sweat response (SSwR) were used to estimate autonomic function in seven AIDP and eight AMAN patients. Heart rate and plasma noradrenaline concentration were significantly high in the AIDP group but not in the AMAN group. Skin vasomotor reflexes were generally preserved and SSwRs were impaired in patients with severe neurological deficits for both AIDP and AMAN groups. The patterns of autonomic involvement are qualitatively different between AIDP and AMAN. Acute inflammatory demyelinating polyneuropathy is characterized by cardio-sympathetic hyperactivity, excessive or reduced sudomotor function and preserved skin vasomotor function, while AMAN is not necessarily generally associated with marked autonomic dysfunction except for the sudomotor hypofunction seen in patients with severe neurological deficits.

Skin Vasomotor Reflex as a Measure of Depth of Anesthesia

Department of Anesthesiology; Kumamoto University School of Medicine; Kumamoto, Japan;shimoda@kaiju.medic.kumamoto-u.ac.jpIn Reply:-Thank you for the opportunity to comment on the report by Ezri et al. and their very interesting observations. We are gratified with the concept “anesthesia management by evaluating autonomic reactivity,” because it may provide important information regarding the depth of anesthesia, as Dr. Anderson pointed out. [1]Laser-Doppler (LD) flowmetry measures superficial cutaneous microcirculation under the probe, whereas plethysmography evaluates changes in the whole blood volume in the finger. The basic wave in LD skin blood flow wave is coincident with the simultaneously recorded baseline fluctuation in the plethysmographic wave. [2]It has not been confirmed whether a linear, quantitative correlation exists between the amplitude of the skin vasomotor reflex measured by LD flowmetry and the pulse amplitude of the plethysmography. The report of Ezri et al. suggests that the changes in the pulse amplitude of plethysmography may also reflect sympathetically mediated vasomotion. Any progress toward an inexpensive and simpler autonomic monitor will prove to be beneficial to the spread of patient-by-patient-based anesthesia management.Analyses of pulse waves (e.g., arterial blood flow, LD skin blood flow, and plethysmography wave) have a common weak point. For example, anesthesia induction with propofol and anaphylactoid reactions increases the pulse amplitude of the plethysmography and LD skin blood flow. This problem has limited the application of pulse wave analysis in assessing the depth of anesthesia. For reducing this problem, we prefer to evaluate autonomic reactivity using a known quantitative stimulus before anesthesia, surgical procedures, or both, rather than to evaluate the changes in autonomic indicators induced by the procedures.Osamu Shimoda, M.D.Department of Anesthesiology; Kumamoto University School of Medicine; Kumamoto, Japan;shimoda@kaiju.medic.kumamoto-u.ac.jp(Accepted for publication June 18, 1998.)