Forearm Temperature Research Articles

External compression increases forearm perfusion

Application of compression stockings to the lower extremities is a widely used therapeutic intervention to improve venous return, but there is little information about the effects of compression on local arterial perfusion. Therefore, we tested the hypothesis that a positive external pressure increases forearm perfusion. The relation of increasing external pressure induced by standardized compression to the arterial inflow and arterial flow reserve of the forearm was critically evaluated in a group of healthy young men (n = 9). Flow was measured with venous occlusion plethysmography after a 10-min application of six different stockings with compression pressure increasing from 13 to 23 mmHg. During compression, the arterial inflow increased significantly from 3.7 +/- 0.85 to 8.8 +/- 2.01 ml.min(-1).100 ml tissue(-1) (P < 0.001) and the arterial flow reserve increased from 17.7 +/- 4.7 to 28.3 +/- 7.0 ml.min(-1).100 ml tissue(-1). The flow increase was persistent after 3 h of constant application of external pressure and also during simultaneous low-intensity hand grip. Similar results obtained with occlusion plethysmography were seen with MRI. During the interventions, forearm temperature was unchanged, and the volunteers reported no discomfort. In conclusion, 1) arterial perfusion of the human forearm increases more than twofold during application of external compression over a pressure range of 13-23 mmHg, and 2) the result is interpreted as an autoregulatory response following the decrease of the vascular transmural pressure gradient.

Temperature Changes and Shivering during Epidural Anesthesia in Women Undergoing Cesarian Delivery

Background: Epidural anesthesia decreases the core temperature triggering vasoconstriction and shivering, presumably by increasing apparent lower-body temperature. We therefore tested the hypothesis that epidural anesthesia in cesarian delivery patients decrease forearm-fingertip skin-surface temperature gradient and it is cause of shivering. Methods: Twenty-two healthy pregnant women were studied. Epidural anesthesia was induced by 2% lidocaine and 0.75% ropivacaine 24 ml (T4 level) at 25 ambient temperature. Shivering were evaluated by observation. Core temperature was recorded in the external auditory canal using a compensated infrared thermometer. Arteriovenous shunt tone was evaluated with forearm- fingertip temperature gradients; gradients less than 0 were considered evidence of vasodilation. Skin-surface temperature, skin- temperature gradients (forearm-fingertip, calf-toe) and the presence or absence of shivering were measured. Results: Shivering was observed in seven of twenty two patients. Sixty minutes after induction, Tympanic temperature decreased for 0.8 0.1 in non-shivering patients and 0.90.1 in shivering patients. Forearm temperature decreased for 0.2 1.7 in non-shivering patients, but increased for 0.50.6 in shivering patients. Upper limb (Forearm-fingertip) skin Temperature gradients continues the plus in non-shivering patients, but maintain minus (45 minutes after induction) in shivering patients. Low limb skin temperature is increases in both group. Conclusions: We failed to confirm our hypothesis, but for an expected reason: shivering was preceded by hypothermia and vasoconstriction in the arm. For prevention of hypothermia in epidural anesthesia, not to be monitored core temperature, but also upper limb skin temperature gradients.

Perspectives for core and skin surface temperature guided extubation in patients after normothermic cardiopulmonary bypass.

To investigate the relationship between changes in core and skin surface temperature and extubation time in patients following normothermic cardiopulmonary bypass (CPB). Prospective observational study. Intensive care unit (ICU) of a university hospital. Patients admitted to the ICU after cardiac surgery. None. Thirty-two patients undergoing cardiac surgery with the use of normothermic CPB were studied. In the ICU, urinary bladder temperature and skin surface temperature gradient (forearm temperature minus fingertip temperature) were measured at 30-min intervals for 10 h postoperatively. Every half-hour an anaesthesiologist, blinded to temperature measurements, checked the possibility of extubation. On arrival in the ICU the mean skin surface temperature gradient of the patients was 1.9+/-1.6 degrees C, indicating vasoconstriction of the dermal vessels (>0 degrees C = vasoconstriction, <0 degrees C = vasodilation) while the mean urinary bladder temperature was 36.8+/-0.4 degrees C. The change from thermoregulatory vasoconstriction to vasodilation (skin surface temperature gradient of 0 degrees C) was 137+/-49 min after arrival in the ICU. The mean time until extubation was 135+/-55 min after arrival in the ICU. There was a linear relation between a temperature gradient of 0 degrees C and extubation time, r(2)=0.49. Later, 181+/-67 min after arrival in the ICU, the urinary bladder temperature reached its maximum of 38.2+/-0.6 degrees C. This study demonstrates that the transition period from peripheral vasoconstriction to vasodilation provides an opportunity for postoperative extubation.

Cutaneous active vasodilation in humans during passive heating postexercise.

The hypothesis that exercise causes an increase in the postexercise esophageal temperature threshold for onset of cutaneous vasodilation through an alteration of active vasodilator activity was tested in nine subjects. Increases in forearm skin blood flow and arterial blood pressure were measured and used to calculate cutaneous vascular conductance at two superficial forearm sites: one with intact alpha-adrenergic vasoconstrictor activity (untreated) and one infused with bretylium tosylate (bretylium treated). Subjects remained seated resting for 15 min (no-exercise) or performed 15 min of treadmill running at either 55, 70, or 85% of peak oxygen consumption followed by 20 min of seated recovery. A liquid-conditioned suit was used to increase mean skin temperature ( approximately 4.0 degrees C/h), while local forearm temperature was clamped at 34 degrees C, until cutaneous vasodilation. No differences in the postexercise threshold for cutaneous vasodilation between untreated and bretylium-treated sites were observed for either the no-exercise or exercise trials. Exercise resulted in an increase in the postexercise threshold for cutaneous vasodilation of 0.19 +/- 0.01, 0.39 +/- 0.02, and 0.53 +/- 0.02 degrees C above those of the no-exercise resting values for the untreated site (P < 0.05). Similarly, there was an increase of 0.20 +/- 0.01, 0.37 +/- 0.02, and 0.53 +/- 0.02 degrees C for the treated site for the 55, 70, and 85% exercise trials, respectively (P < 0.05). It is concluded that reflex activity associated with the postexercise increase in the onset threshold for cutaneous vasodilation is more likely mediated through an alteration of active vasodilator activity rather than through adrenergic vasoconstrictor activity.

Effect of limb cooling on peripheral and global oxygen consumption in neonates

Aim: To evaluate peripheral oxygen consumption (Vo2) measurements using near infrared spectroscopy (NIRS) with arterial occlusion in healthy term neonates by studying the effect of limb cooling on peripheral and...

Comparative effects of ringer's acetate and lactate solutions on intraoperative central and peripheral temperatures

Study Objectives: To compare the effects of Ringer's lactate (LR) and Ringer's acetate (AR) solutions on core body and peripheral temperatures during isoflurane or sevoflurane anesthesia. Design: Prospective, randomized study. Setting: Operating rooms of a university hospital. Patients: 60 ASA physical status I and II patients undergoing general surgery. Interventions: Following induction with 5 mg/kg of thiamylal and 0.1 mg/kg of vecuronium, patients were randomly assigned to one of four groups (15 patients per group). They received inhalation anesthetics (66% nitrous oxide [N 2O] and 1.0% to 2.0% isoflurane or 1.3% to 2.6% sevoflurane) and LR or AR. Measurements and Main Results: Tympanic membrane (central) temperatures, forearm temperatures, and fingertip temperatures were recorded during surgery every 30 minutes. Tympanic membrane temperatures in the patients given AR were significantly higher than those given LR during isoflurane anesthesia 5 and 30 minutes after induction of anesthesia. However, this was not the case for sevoflurane anesthesia. There were no significant differences in forearm and fingertip temperatures or fingertip blood flow among the four groups. Conclusion: There was no significant difference between AR and LR in the preservation of heat during either sevoflurane or isoflurane anesthesia. However, AR may be superior to LR for maintaining central temperature during the early period of isoflurane anesthesia.

Muscle cooling delays activation of the muscle metaboreflex in humans

Elevation of muscle temperature has been shown to increase muscle sympathetic nerve activity (MSNA) during isometric exercise in humans. The purpose of the present study was to evaluate the effect of muscle cooling on MSNA responses during exercise. Eight subjects performed ischemic isometric handgrip at 30% of maximal voluntary contraction to fatigue followed by 2 min of postexercise muscle ischemia (PEMI), with and without local cooling of the forearm. Local cooling of the forearm decreased forearm muscle temperature from 31.8 +/- 0.4 to 23.1 +/- 0.8 degrees C (P = 0.001). Time to fatigue was not different during the control and cold trials (156 +/- 11 and 154 +/- 5 s, respectively). Arterial pressures and heart rate were not significantly affected by muscle cooling during exercise, although heart rate tended to be higher during the second minute of exercise (P = 0.053) during muscle cooling. Exercise-induced increases in MSNA were delayed during handgrip with local cooling compared with control. However, MSNA responses at fatigue and PEMI were not different between the two conditions. These findings suggest that muscle cooling delayed the activation of the muscle metaboreflex during ischemic isometric exercise but did not prevent its full expression during fatiguing contraction. These results support the concept that muscle temperature can play a role in the regulation of MSNA during exercise.

Comparison of the effects of sodium nitroprusside and isoflurane during rewarming on cardiopulmonary bypass

Objectives: Afterdrop in core temperatures after discontinuation of cardiopulmonary bypass (CPB) is reported to be a sign of inadequate total body rewarming on CPB. The purpose of this study was to compare the effects of three different drug regimens on hemodynamic stability and the uniformity of rewarming during the rewarming period of CPB. Design: This prospective randomized study was performed in the Anesthesiology Department of the University of Istanbul. Participants: Sixty-six patients undergoing uncomplicated valve replacement and aortocoronary bypass grafting surgery were studied. Interventions: Anesthesia was maintained with isoflurane and fentanyl infusion during the prebypass and the postbypass periods. Patients were allocated into three groups by the initiation of CPB. Group 1 (n = 22): fentanyl infusion + diazepam + sodium nitroprusside (SNP) (in the rewarming period), group 2 (n = 22): fentanyl infusion + isoflurane, group 3, control (n = 22): fentanyl infusion + diazepam. Rectal, esophageal, and forearm temperatures were monitored throughout the study. Measurements and Main Results: None of the durational and temperature data showed significant differences between groups 1 and 2. In the control group, afterdrop in esophageal temperature was significantly higher than groups 1 and 2 (group 1: −1.4 ± 0.9°C, group 2: −1.44 ± 0.8°C, group 3: −2.1 ± 0.65°C). In group 1, the number of patients whose mean arterial pressure (MAP) decreased below 45 mmHg was significantly higher than group 2 ( p = 0.002). Mean SNP infusion rate and mean isoflurane concentration during the rewarming period were calculated as 1.55 ± 0.8 μg/kg/min and 0.775 ± 0.27%, respectively. Conclusions: Isoflurane produced more stable hemodynamic conditions than SNP during the rewarming period, improved the uniformity of rewarming, and permitted earlier extubation in the intensive care unit (ICU). It is concluded that isoflurane alone is capable of fulfilling the anesthesia needs during hypothermia and the rewarming period of CPB.

Shooting performance is related to forearm temperature and hand tremor size.

The changes in postural tremor of the hand and the subsequent effect on shooting performance produced by moderate cooling and heating of the forearm were studied in six subjects. Cooling produced a large decrease in tremor size of the ipsilateral hand, whereas warming the limb produced an increase in tremor size. Cooling or warming the forearm did not change the peak frequency of tremor significantly, which was quite stable for each subject. The improvement in shooting performance after cooling the forearm, as measured by grouping pattern of the shots, reached statistical significance and warming caused a significant worsening. This measure of performance was shown to correlate (r = 0.776) inversely with tremor size. The causes and implications of these changes are discussed. It is suggested that local cooling may be useful for people who wish temporarily to reduce tremor in order to improve dexterity for shooting and for other purposes.

Forearm temperature profile during the transient phase of thermal stress.

The transient temperature response of the resting human forearm immersed in water at temperatures (Tw) ranging from 15 to 36 degrees C was investigated. Tissue temperature (Tt) was continuously monitored by a calibrated multicouple probe during the 3-h immersions. Tt was measured every 5 mm, from the longitudinal axis of the forearm to the skin surface. Skin temperature, rectal temperature, and blood flow (Q) were also measured during the immersions. The maximum rate of change of the forearm mean tissue temperature (Tt, max) occurred during the first 5 min of the immersion. Tt, max was linearly dependent on Tw (P less than 0.001), with mean values (SEM) ranging from -0.8 (0.1) degrees C.min-1 at 15 degrees C to 0.2 (0.1) degrees C.min-1 at 36 degrees C. The maximum rate of change of compartment mean temperature was dependent (P less than 0.001) on the radial distance from the longitudinal axis of the forearm. The half-time for thermal steady state of the forearm mean tissue temperature was linearly dependent on Tw between 30 and 36 degrees C (P less than 0.01), with mean values (SEM) ranging from 15.6 (0.6) min at 30 degrees C to 9.7 (1.2) min at 36 degrees C and not different between 15 and 30 degrees C, averaging 16.2 (0.6) min. There was a significant linear relationship between the half-time for thermal steady-state of the compartment mean temperature and the radial distance from the longitudinal axis of the forearm for each value of Tw tested (P less than 0.001). The data of the present study suggest that the forearm Q is an important determinant of the transient thermal response of the forearm tissue during thermal stress.

Skin-surface Temperature Gradients Correlate with Fingertip Blood Flow in Humans

Skin-surface temperature gradients (forearm temperature - fingertip temperature) have been used as an index of thermoregulatory peripheral vasoconstriction. However, they have not been specifically compared with total finger blood flow, nor is it known how long it takes fingertip temperature to fully reflect an abrupt change in finger blood flow. Steady-state skin-temperature gradients were compared with total fingertip blood flow in 19 healthy volunteers. There was an excellent correlation between steady-state skin-surface temperature gradients and total fingertip blood flow measured with venous-occlusion volume plethysmography: gradient = 0.2-5.7.log(flow), r = 0.98. The half-time for fingertip cooling after complete arterial obstruction (in 8 volunteers) was 6.6 +/- 1.2 min. The authors conclude that skin-temperature gradients are an accurate measure of thermoregulatory peripheral vasoconstriction.

Responses of skin temperature to different thermic stimuli in atopic eczema.

Patients suffering from atopic eczema (AE) often exhibit general disturbances of vasovegetative skin functions. Thus, in 21 patients with AE we studied the response of the skin of one forearm to standardized 15-min exposure of the other forearm to a moderate cold bath (17-18 degrees C) and then, after a resting time, to a hot bath (40-41 degrees C). The results were compared with those in 23 age- and sex-matched healthy controls under the same experimental conditions. In most patients, the unilateral skin exposure to warmth left the temperature of the contralateral forearm nearly unchanged or even slightly decreased, whereas the exposure to cold induced either a slight rise in contralateral skin temperature or only a minute decrease. In contrast to the normal consensual temperature reaction of the non-exposed forearm to warmth exposure of the contralateral arm in most controls, the results in atopic patients indicate a "rigid" or even inverse ("paradoxical") response to the thermic stimuli applied. This abnormal pattern of thermoregulation may reflect an intrinsic disturbance of the peripheral and hypothalamic autonomous neural system involved in the pathogenetic conditions of AE.

Modification of the cutaneous vascular response to exercise by local skin temperature.

This study examined how local forearm temperature (Tloc) affects the responsiveness of the cutaneous vasculature to a reflex drive for vasoconstriction. We observed responses in forearm blood flow (FBF) and arterial blood pressure to a 5-min bout of supine leg exercise of moderate intensity (125-175 W) after the forearm had been locally warmed to 36, 38, 40, or 42 degrees C for 48 min. With exercise, FBF fell by 1.82 +/- 0.23, 4.06 +/- 0.58, and 3.64 +/- 1.48 ml X 100 ml-1 X min-1 at 36, 38, and 40 degrees C, respectively, and rose by 2.16 +/- 0.57 ml X 100 ml X min-1 at a Tloc of 42 degrees C (mean +/- SE). Forearm vascular conductance (FVC) fell with the onset of exercise by averages of 2.77 +/- 0.57, 7.02 +/- 0.51, 5.36 +/- 0.85, and 4.17 +/- 0.79 ml X 100 ml-1 X min-1 X 100 mmHg-1 at 36, 38, 40, and 42 degrees C, respectively. Second-order polynomial regression analysis indicated that the reductions in FVC were greatest near a Tloc of 39 degrees C and that at a Tloc of 40 or 42 degrees C the cutaneous vasoconstrictor response to the onset of exercise is attenuated. Although elevated Tloc can be used to increase base-line FBF levels to make cutaneous vasoconstrictor responses more obvious, the direct effects of Tloc on this response must also be considered. We conclude that the optimum Tloc for observing reflex cutaneous vasoconstriction is near 39 degrees C.

Responses of forearm blood flow to graded leg exercise in man

To test whether the cutaneous vascular responses to exercise are influenced by the level of work, three strategies were followed. In each, forearm blood flow and esophageal temperature were measured throughout. In part I, the forearm blood flow-internal temperature relationships from separate sessions of steady-state exercise at different loads were compared. In part II, work load was varied between 50 and 150 W. Work load was raised or lowered 50 W every 5 min over 60-75 min. The third strategy was to examine the immediate change in forearm blood flow accompanying rapid, large increments or decrements in work load. The results do not support a graded response of the cutaneous circulation to exercise. In both the first and second protocols above, the relationship of forearm blood flow to internal temperature was not measurably altered by work load. Multiple linear regression analysis failed to reveal a consistent role for work load in part II. In the third protocol, there was no consistent or sustained response to an abrupt change in work load. Thus over the range of work loads used in this study there appears to be no major role for the level of work in the regulation of forearm skin blood flow other than through the effect on internal temperature.

Isometric strength and endurance during the menstrual cycle.

Seven healthy young women, 3 whom had been taking oral contraceptives, were examined during the course of 2 menstrual cycles to assess their isometric strength, their endurance during a series of 5 fatiguing isometric contractions at a tension of 40% MVC, and their blood pressures and heart rates during those fatiguing contractions. Two sets of experiments were performed, one in which the subject's forearm temperature was allowed to vary as a function of T A, and one with the muscle temperature stabilized by immersion of the forearm in water at 37 degrees C. During exposure to ambient temperatures, isometric strength and both the heart rate and blood pressure responses at rest and at the end of a fatiguing, sustained isometric exercise, were not significantly different during any phase of the menstrual cycle in any subject. In contrast, the isometric endurance in the women not taking oral contraceptives varied sinusoidally in all 5 contractions with a peak endurance midway through the ovulatory phase and the lowest endurance mid-way through the luteal phase of the menstrual cycle. The isometric endurance of the women taking oral contraceptives did not vary during their menstrual cycle. After stabilization of the temperature of the muscles of the forearm in water at 37 degrees C, the isometric endurance of the normal subjects showed a hyperbolic response with the maximal endurance at the beginning and end of their cycles, and the shortest endurance at mid-cycle. Here again, however, the isometric endurance of the women taking oral contraceptives did not vary after immersion of their forearms in the 37 degree C water.

Skin temperature in hot environment.

It has been suggested that the immersion of subjects into a hot water bath (Bath Method) may be useful and simple method for testing human heat tolerance. It is probable that the bath method may fail to evaluate valid heat tolerance because of the forced uniformization of skin temperature. To confirm the validity of the bath method, sublingual temperature and skin temperature of forehead, chest, back, forearm, thigh and calf were examined when the two adult male subjects were exposed to various hot air environment in the nude for an hour in the sitting position. The following results were obtained.1) On every skin temperature measured at six different regions, the difference of skin temperature between the two subjects observed under the very hot condition was smaller than that observed under the cooler condition.2) The range of skin temperature (the difference between the highest and the lowest value among skin temperatures measured at six different regions) was rather small under very hot conditions.3) Relatively large positive correlations were found among every skin temperature measured at six different regions. It was revealed by the principal component analysis that skin temperatures at various regions were controlled mostly by a single common factor.The above findings indicate that the forced uniformization of skin temperature brought about by the bath method will not necessarily interfere with the valid evaluation of human heat tolerance.

Mechanical factors in human tremor frequency.

Mechanical factors in human tremor frequency.