Effect of spinal sympathetic blockade upon postural changes of blood flow in human peripheral tissues

Integrative review of non-pharmacological intervention and multidimensional evaluation for intraoperative anxiety under spinal anaesthesia

INTRODUCTION

Patients under spinal anaesthesia experience high levels of anxiety during surgery. Clinical nurses tried to manage patient's anxiety under spinal anaesthesia using non-pharmacological interventions for its benefit. Thus, it is required to identify comprehensive evidences of various non-pharmacological interventions and of how to measure anxiety under spinal anaesthesia.

AIMS

This study aims to review current research on the non-pharmacological interventions to relieve intraoperative anxiety under spinal anaesthesia and to identify subjective and objective measures of intraoperative anxiety under spinal anaesthesia.

METHODS

Wittemore and Knafl's integrative review methodology was used. Researchers conducted five scientific rigor steps; problem identification, searching literature, evaluation of literature, analysis of literature and presentation of results. The PRISMA checklist was used. To evaluate the level of evidence, critical appraisal tools of Joanna Briggs Institute were used.

RESULTS

Eleven studies were included in this integrative review. Delivering music is the most frequently used as non-pharmacological intervention by researchers. They tried to manage intraoperative anxiety under spinal anaesthesia with using diverse genre and application of music. In addition, dry cupping method, progressive muscle relaxation (PMR) exercise and virtual reality (VR) goggles were used in included studies. Researchers measured intraoperative anxiety under spinal anaesthesia with objective or subjective way. The State-Trait Anxiety Inventory and visual analogue scale were used as subjective method to approach intraoperative anxiety. In contrary, researchers tried to obtain objective evidence of intraoperative anxiety with vital signs, cortisol, blood glucose, alpha-amylase and adrenocorticotropic hormone.

CONCLUSION

Various types of non-pharmacological interventions are effective to manage patient's intraoperative anxiety under spinal anaesthesia. It is recommended to measure intraoperative anxiety under spinal anaesthesia with using both objective and subjective methods.

RELEVANCE TO CLINICAL PRACTICE

Clinical nurses can use non-pharmacological interventions to manage intraoperative anxiety under spinal anaesthesia by comprehensive monitoring with diverse measures.

Impact of tetraplegia vs. paraplegia on venoarteriolar, myogenic and maximal cutaneous vasodilation responses of the microvasculature: Implications for cardiovascular disease

Objective: Cardiovascular disease (CVD) is a leading cause of mortality in persons with SCI. While macrovascular remodeling and function after SCI is well documented, changes in the microvascular structure and function are comparably understudied, but importantly predict CVD risk. Specifically, the integrity of venoarteriolar (VAR), myogenic (MYO) and maximal vasodilation responses are largely unknown after SCI, especially in persons with tetraplegia (TP) at highest risk of CVD. This is the first to examine the differences in VAR (cuff inflation), MYO (limb dependency) and maximal vasodilation responses of the microvasculature between able bodied (AB) versus those with TP and paraplegia (PP).Design: Observational.Setting: Laboratory.Participants: Eight AB, 6 TP, and 8 PP persons.Interventions: One forearm and calf were treated topically with lidocaine 2.5%/prilocaine 2.5% while contralateral limb served as a control. Laser doppler flowmeters were applied over treated and control sites during limb dependency, cuff inflation and local skin heating (Tloc) up to 42°C.Outcome measures: Skin vascular resistance (SkVR) change with cuff inflation and limb dependency and maximal cutaneous vascular conductance (CVC) during local heating.Results: Change in SkVR was not significantly different between groups or extremity (upper vs. lower) during cuff inflation or limb dependency. However, CVC at Tloc 42°C was significantly different in the lower extremity (LE) of TP and PP (P = 0.007, 0.35) compared to AB.Conclusion: Increases in SkVR during cuff inflation (VAR) and limb dependency (VAR and MYO) are unaltered after SCI, however maximal vasodilation in the LE post-SCI is higher than AB persons.

Baroreflex autonomic control in human spinal cord injury: Physiology, measurement, and potential alterations

The arterial baroreflex is a primary regulator of autonomic outflow to effectively regulate acute changes in blood pressure. After a spinal cord injury (SCI), regulation of autonomic function is disrupted, although the damage of the autonomic pathways may not necessarily be related to the severity of injury (i.e. level and completeness). Nonetheless, it can be assumed that there would be greater loss of sympathetic innervation with higher level of injury and that cardiac parasympathetic control would remain intact regardless of injury level. In those with SCI, impaired baroreflex regulation has implications not only for adequate pressure regulation, but also for long term cardiovascular health. In this review, we discuss the expected impact ofan SCI on baroreflex control and the studies that have investigated baroreflex sensitivity in this population. The data generally indicates that baroreflex sensitivity is lesser in those with chronic injuries. However, these findings are counter to the expected effect of an SCI and hence may indicate that the effect of an SCI on baroreflex control might be secondary to long term deconditioning and/or vascular stiffening of baroreceptive arteries. Furthermore, the alterations in the ability to regulate pressure do not impact the relationship between spontaneous heart rate and blood pressure variabilities. In addition, those with SCI are not adequately able to control blood pressure changes in response to orthostasis, resulting in frank hypotension in a significant proportion of those with high level injuries.

In Vivo Evaluation of Femoral Blood Flow Measured with Magnetic Resonance

Quantitative measurements of blood flow based on magnetic resonance imaging (MRI) using conventional multiple spin echo sequences were evalutated in vivo in healthy young volunteers. Blood flow was measured using MRI in the femoral vein. The initial slope of the multiple spin echo decay curve, corrected for the T2 decay of non-flowing blood was used to calculate the blood flow. As a reference, the blood flow in the femoral artery was measured simultaneously with an invasive indicator dilution technique. T2 of non-flowing blood was measured in vivo in popliteal veins during regional circulatory arrest. The mean T2 of non-flowing blood was found to be 105 ±31 ms. The femoral blood flow ranged between 0 and 643 ml/min measured with MRI and between 280 and 531 ml/min measured by the indicator dilution technique. There was thus poor agreement between the two methods. The results indicate that in vivo blood flow measurements made with MRI based on wash-out effects, commonly used in multiple spin echo imaging, do not give reliable absolute values for blood flow in the femoral artery or vein.

Leg vascular resistance increases during head-up tilt in paraplegics

Despite loss of centrally mediated sympathetic vasoconstriction to the legs, spinal cord-injured individuals cope surprisingly well with an orthostatic challenge. This study assessed changes in leg vascular resistance following head-up tilt in healthy (C) and in paraplegic (P) individuals. After 10 min of supine rest, subjects were tilted 30 degrees head-up. Mean arterial pressure (MAP) and total peripheral resistance (TPR) increased in C (MAP from 76.7 +/ -6.6 mmHg to 80.6 +/- 8.2 mmHg; TPR from 1.12 +/- 0.26 AU to 1.19 +/ -0.31 AU) while both remained unchanged in P. Echo Doppler ultrasound determined red blood cell velocity in the femoral artery, which decreased (P from 18.9+/-6.2 cm/s to 12.5 +/- 4.5 cm/s, P = 0.001; C from 16.3 +/- 6.2 cm/s to 10.8 +/- 5.0 cm/s, P = 0.001) and leg vascular resistance, which increased (P from 402 +/- 137 AU to 643 +/- 274 AU, P = 0.001; C from 238 +/- 68 AU to 400 +/- 122 AU, P = 0.003) from supine to upright. The present study shows that independent of supraspinal sympathetic control, humans are able to increase leg vascular resistance and maintain blood pressure during head-up tilt.

Effect of local heating and vasodilation on the cutaneous venoarteriolar response

The cutaneous venoarteriolar response (CVAR) is a local non-adrenergic vasoconstrictor reflex that is engaged via increases in local transmural pressure. The purpose of this study was to determine if local temperature alters the vasoconstrictor ability of the CVAR. Twelve (5 male, 7 female) subjects performed a CVAR maneuver at local temperatures of 30+/-1, 34, 38, and 42 degrees C. CVAR was also engaged after vasodilation via intradermal perfusion of sodium nitroprusside or the attenuation of local heating-induced vasodilation via intradermal perfusion of N(G)-nitro-L: -arginine methyl ester (L: -NAME) in five subjects (2 male, 3 female). CVAR was elicited by rapid cuff inflation to 45mmHg proximal to two dorsal forearm sites for 2 min in both protocols. Local heating caused a progressive increase in skin blood flow (8+/-1, 18+/-4, 43+/-11, and 78+/-2% maximal skin blood flow for 30+/-1, 34, 38, and 42 degrees C, respectively). Engagement of the CVAR decreased skin blood flow by 53+/-2, 57+/-3, and 51+/-4%, for 30+/-1, 34, and 38 degrees C, respectively. In contrast, local heating to 42 degrees C significantly attenuated the CVAR (16+/-11 %). Local administration of sodium nitroprusside during neutral temperature and L: -NAME during local heating also significantly attenuated the vasoconstrictor response of the CVAR by 27+/-8 and 38+/-4%, respectively. These data indicate that CVAR is attenuated at high (42 degrees C) local skin temperatures and that this attenuation is likely due to an effect of both local heating-induced vasodilation and a direct temperature effect.

Sympathetic dysfunction of central origin in patients with ALS

Amyotrophic lateral sclerosis (ALS) is a severe, progressive disease affecting both the central and peripheral parts of the motor nervous system. Some studies have shown unequivocal indications of a more disseminated disease also affecting the autonomic nervous system. We therefore evaluated the centrally and peripherally mediated autonomic vascular reflexes by (i) the local 133-Xenon washout technique, and (ii) the head-up tilt table test. The results correlated to clinical scores. We examined nine ALS patients and 15 age-matched controls. The 133-Xenon washout test showed a significant reduction in the centrally mediated sympathetic vasoconstrictor response, but a preserved locally mediated response in the patients. In the head-up tilt table test, the patients had a significantly higher mean arterial blood pressure (MAP) compared with controls, probably due to a general increase in vascular resistance. There were no correlations between the ALS Severity Scores and blood flow changes, diastolic blood pressure or MAP. Our study supports previous results, but indicates abnormalities consistent with a solely centrally located sympathetic dysfunction in ALS, independent of the stage of the disease.

Evaluation of orthostatic blood pressure testing as a discharge criterion from PACU after spinal anesthesia

Discharge readiness from a Phase I PACU after spinal anesthesia is frequently determined by recovery of sensory/motor function. However, no data exist indicating that recovery of sensory/motor function adequately predicts hemodynamic stability after spinal anesthesia. The conservative practice of waiting until the sensory/motor effects of spinal anesthesia have completely worn off often requires patients to remain in PACU for prolonged periods of time. The purpose of this study was to determine the safety and efficacy of using orthostatic blood pressure (BP) testing as a discharge criterion from PACU after spinal anesthesia. This study used a prospective, descriptive design to measure changes in mean arterial pressure (MAP) during orthostatic BP testing at 30-minute intervals after admission to the PACU following spinal anesthesia. A convenience sample of 121 patients admitted through the Same Day Surgery (SDS) unit was used. Results show that orthostatic BP criterion was safe and effective as an alternative to sensory/motor criteria in assessing hemodynamic stability and reducing the amount of time patients spend in the PACU after spinal anesthesia. This is a U.S. government work. There are no restrictions on its use.

Forearm vascular and neuroendocrine responses to graded water immersion in humans

The hypothesis that graded expansion of central blood volume by water immersion to the xiphoid process and neck would elicit a graded decrease in forearm vascular resistance was tested. Central venous pressure increased (P < 0.05) by 4.2 +/- 0.4 mmHg (mean +/- SEM) during xiphoid immersion and by 10.4 +/- 0.5 mmHg during neck immersion. Plasma noradrenaline was gradually suppressed (P < 0.05) by 62 +/- 8 and 104 +/- 11 pg mL-1 during xiphoid and neck immersion, respectively, indicating a graded suppression of sympathetic nervous activity. Plasma concentrations of arginine vasopressin were suppressed by 1.5 +/- 0.5 pg mL-1 (P < 0.05) during xiphoid immersion and by 2.0 +/- 0.5 pg mL-1 during neck immersion (P < 0.05 vs. xiphoid immersion). Forearm subcutaneous vascular resistance decreased to the same extent by 26 +/- 9 and 28 +/- 4% (P < 0.05), respectively, during both immersion procedures, whereas forearm skeletal muscle vascular resistance declined only during neck immersion by 27 +/- 6% (P < 0.05). In conclusion, graded central blood volume expansion initiated a graded decrease in sympathetic nervous activity and AVP-release. Changes in forearm subcutaneous vascular resistance, however, were not related to the gradual withdrawal of the sympathetic and neuroendocrine vasoconstrictor activity. Forearm skeletal muscle vasodilatation exhibited a more graded response with a detectable decrease only during immersion to the neck. Therefore, the forearm subcutaneous vasodilator response reaches saturation at a lower degree of central volume expansion than that of forearm skeletal muscle.

Effect of epidural anaesthesia on dorsal pedis arterial diameter and blood flow

In nine subjects the influence of low (LE: blockade at or below the umbilicus; Th. 10) and high epidural anaesthesia (HE: block above the umbilicus) on vascular tone was evaluated by high frequency ultrasound (20 mHz) determined luminal diameter and a Doppler (8 mHz) assessment of mean blood flow velocity (Vmean) in the dorsalis pedis artery. The LE was induced by 0.5% bupivacain through a catheter at L3-L4, and HE was established by further infusion. Resting blood pressure and heart rate were not affected by LE or HE. One subject developed selective thoracic anaesthesia, and another was blocked on the contralateral side only. In the seven adequately blocked subjects, the luminal diameter of the dorsalis pedis artery increased from 1.70 (1.25-1.93) to 1.90 (1.75-2.23) mm during LE (+12%) and further to 2.08 (1.83-2.96) mm during HE (22%; P < 0.05). The Vmean was similar during control (7[4-26] cm s-1) and LE (12[4-55] cm s-1), but increased during HE to 35(12-78 cm s-1 (+500%; P < 0.05). Thus, arterial blood flow was higher during LE (21[7-98] ml min-1; +263%) and HE (94[21-177] ml min-1; +1175%) than at rest (8[7-36] ml min-1; P < 0.05). This study quantified the importance of sympathetic nerve activity for vascular tone and in turn blood flow in an artery of a resting human limb, as the diameter and Vmean increased with progressive epidural anaesthesia.

Abnormal baroreceptor-mediated vasodilation of the peripheral circulation in congestive heart failure secondary to idiopathic dilated cardiomyopathy

BACKGROUND

Peripheral edema is a major clinical problem in congestive heart failure (CHF). The function of the edema-protective baroreceptor-mediated and local nervous vasoconstrictor reflexes of the lower leg during orthostasis in moderate and severe CHF has largely been unexplored.

METHODS AND RESULTS

Baroreceptor-mediated and local nervous regulation of subcutaneous blood flow of the lower leg was studied in healthy subjects and in patients with moderate and severe CHF secondary to idiopathic dilated cardiomyopathy. Blood flow was measured by the local 133Xe washout method in the supine position and during 45 degrees head-up tilt. When the central baroreceptor reflex alone was activated, the changes in subcutaneous blood flow of the heart failure patients in both groups were significantly different from those of the eleven control subjects: blood flow increased 48 +/- 26% in 10 severe and 3 +/- 24% in nine moderate CHF patients compared with the decrease in blood flow of -36 +/- 15% observed in 11 control subjects (p < 0.0001 for both). A highly significant direct association was demonstrated between changes in blood flow and New York Heart Association functional class (p = 0.007) and the left ventricular ejection fraction (p = 0.01). Activation of the baroreceptor and local venoarteriolar axon reflexes simultaneously increased blood flow significantly (30 +/- 9%) in 14 patients with severe CHF, compared with the decrease found in 14 control subjects (-53 +/- 9%) and in the group of 14 patients with moderate CHF (-17 +/- 25%) (p < 0.0001 for both).

CONCLUSIONS

Patients with CHF secondary to idiopathic dilated cardiomyopathy have an abnormal baroreceptor-mediated vasodilation in subcutaneous tissue of the lower leg during the upright position, which increases with the severity of the disease. The hemodynamic consequence is capillary hypertension and hyperemia in the leg during the upright position that may contribute to the development of edema and to the initiation of structural changes (microangiopathy) demonstrated in the microcirculation.

Effect of spinal versus epidural anaesthesia with 0.5% bupivacaine on lower limb blood flow

Changes in the haemodynamics of the lower extremities, big toe temperature, blood pressure and heart rate were studied in 20 patients undergoing spinal or epidural anaesthesia for transurethral surgery. Calf blood flow was determined by strain gauge plethysmography (SGP) and Doppler ultrasound. Bupivacaine 0.5% was injected at the L3-L4 interspace, the dose being 3-4 ml (mean 3.6) in the spinal and 17-20 ml (mean 18.6) in the epidural group. The number of sensory blocked segments 30 min after anaesthesia was 12.7 +/- 0.7 (mean +/- s.e.mean) and 14.4 +/- 0.7, respectively. Only minor decreases in blood pressure were noted following the blocks. Heart rate remained virtually unchanged. The increase in skin temperature was more pronounced (P less than 0.01) following epidural (mean 8 degrees C) than spinal anaesthesia (mean 4 degrees C). In addition, the arterial blood flow was significantly higher (P less than 0.05) following epidural than spinal block (means 3.5 and 2.2 ml/100 ml/min, respectively). The venous capacity and maximum venous outflow remained practically unchanged in both groups. Obviously, epidural anaesthesia with bupivacaine causes a more intensive sympathetic block than does spinal anaesthesia. As probably no venous pooling occurred, when examined by SGP and Doppler ultrasound, neither of the blocks is likely to contribute to the initiation of deep vein thrombosis.

Sympathetic reflex control of skeletal muscle blood flow in patients with congestive heart failure: evidence for beta-adrenergic circulatory control

Mechanisms controlling forearm muscle vascular resistance (FMVR) during postural changes were investigated in seven patients with severe congestive heart failure (CHF) and in seven control subjects with unimpaired left ventricular function. Relative brachioradial muscle blood flow was determined by the local 133Xe-washout technique. Unloading of baroreceptors with use of 45 degree upright tilt was comparably obtained in the patients with CHF and control subjects. Control subjects had substantially increased FMVR and heart rate to maintain arterial pressure whereas patients with CHF had decreased FMVR by 51 +/- 11% (mean +/- SEM, p less than .02) and had no increase in heart rate despite a fall in arterial pressure during upright tilt. The autoregulatory and local vasoconstrictor reflex responsiveness during postural changes in forearm vascular pressures were intact in both groups. Further investigations were carried out in the patients with CHF. The left axillary nerve plexus was blocked by local anesthesia in the seven patients. No alterations in forearm vascular pressures were observed. This blockade preserved the local regulation of FMVR but reversed the vasodilator response to upright tilt as FMVR increased by 30 +/- 7% (p less than .02). Blockade of central neural impulses to this limb combined with brachial arterial infusions of phentolamine completely abolished the humoral vasoconstriction in the tilted position. Infusions of propranolol to the contralateral brachial artery that did not affect baseline values of heart rate, arterial pressure, or the local reflex regulation of FMVR reversed the abnormal vasodilator response to upright tilt as FMVR increased by 42 +/- 12% (p less than .02). Despite augmented baseline values, forearm venous but not arterial plasma levels of epinephrine increased in the tilted position, as did arterial rather than venous plasma concentrations of norepinephrine in these patients. The results suggest a beta-adrenergic reflex mechanism elicited by spinal or supraspinal neural impulses and probably modulating a cotransmitter release in the patients with CHF.

Contribution of local blood flow regulation mechanisms to the maintenance of arterial pressure in upright position during epidural blockade

The contribution of local blood flow regulation mechanisms to the maintenance of arterial pressure in upright position was studied in 5 normal subjects. Central sympathetic blockade was induced by epidural anesthesia. Blood flow in anterior tibial muscle in both legs and in brachioradial muscle in one arm was measured by the local 133Xe washout technique. Arterial blood pressure was recorded directly from the radial artery. Slow head-up tilt (about 30 degrees) caused a decrease in blood flow of about 36% in the dependent legs and in arm remaining at heart level. Arterial pressure decreased by about 10%. Blockade of the local sympathetic veno-arteriolar "axon reflex" in one leg by injection of phentolamine into the common femoral artery caused a vasodilatation in the ipsilateral muscle, while muscle blood flow did not change in the other leg or arm. Within 20 s after the injection of phentolamine arterial pressure decreased by about 7%. This cannot be explained by a "systemic" effect because injection of phentolamine into the femoral vein did not effect arterial pressure within the first 40 s. Vasoconstriction due to blood-borne factors is ruled out since preventing the increase in vascular transmural pressure in the leg by inducing counterpressure locally, abolished the vasoconstriction. Thus, the results suggest that the local veno-arteriolar "axon reflex" together with myogenic mechanisms contribute to the maintenance of arterial pressure in the upright position.

Contribution of local blood flow regulation mechanisms during head-up tilt in human subcutaneous tissue

Local and remote regulation of subcutaneous blood flow in the forearm and leg was studied during head-up tilt (30 degrees, 45 degrees and 70 degrees) in 7 young healthy subjects. Relative blood flow was estimated by the local 133Xe washout technique. Incremental levels of head-up tilt elicited increasing vascular resistance on arm and leg, respectively. Positive pressure similar to a blood column of the same height was able to prevent a significant part of the vasoconstrictor response on the leg to head-up tilt. Thus if venous distension is prevented the local veno-arteriolar reflex is abolished, whereas arteriolar constriction due to centrally elicited reflexes remains unaffected. Subcutaneous blood flow in the extremities are regulated by remote (baroreceptor) as well as local sympathetic reflex mechanisms (veno-arteriolar reflex); but the relative influence of the local veno-arteriolar reflex on the increase in total peripheral resistance seems to decrease with increasing tilt angles.