Ice-Water Hand Immersion Causes a Reflex Decrease in Skin Temperature in the Contralateral Hand

Non-Contact Assessment of Peripheral Artery Haemodynamics Using Infrared Video Thermography

Skin temperature has long been used as a natural indicator of vascular diseases in the extremities. Considerable correlation between oscillations in skin surface temperature and oscillations of skin blood flow has previously been demonstrated. We hypothesised that the impairment of blood flow in stenotic (subcutaneous) peripheral arteries would influence cutaneous temperature such that, by measuring gradients in the temperature distribution over skin surfaces, one may be able to diagnose or quantify the progression of vascular conditions in whose pathogenesis a reduction in subcutaneous blood perfusion plays a critical role (e.g. peripheral artery disease). As proof of principle, this study investigates the local changes in the skin temperature of healthy humans (15 male, [Formula: see text] years old, BMI [Formula: see text] kg/m ²) undergoing two physical challenges designed to vary their haemodynamic status. Skin temperature was measured in four central regions (forehead, neck, chest, and left shoulder) and four peripheral regions (left upper arm, forearm, wrist, and hand) using an infrared thermal camera. We compare inter-region patterns. Median temperature over the peripheral regions decreased from baseline after both challenges (maximum decrease: [Formula: see text] °C at 60 s after exercise; [Formula: see text] and [Formula: see text] °C at 180 s of cold-water immersion; [Formula: see text]). Median temperature over the central regions showed no significant changes. Our results show that the non-contact measurement of perfusion-related changes in peripheral temperature from infrared video data is feasible. Further research will be directed towards the thermographic study of patients with symptomatic peripheral vascular disease.

Splenic Blood Flow Increases after Hypothermic Stimulus (Cold Pressor Test): A Perfusion Magnetic Resonance Study

The Cold Pressor Test (CPT) is a novel diagnostic strategy to noninvasively assess the myocardial microvascular endothelial-dependent function using perfusion magnetic resonance imaging (MRI). Spleen perfusion is modulated by a complex combination of several mechanisms involving the autonomic nervous system and vasoactive mediators release. In this context, the effects of cold temperature on splenic blood flow (SBF) still need to be clarified. Ten healthy subjects were studied by MRI. MRI protocol included the acquisition of GRE T1-weighted sequence (“first pass perfusion”) during gadolinium administration (0.1mmol/kg of Gd-DOTA at flow of 3.0 ml/s), at rest and after CPT. Myocardial blood flow (MBF) and SBF were measured by applying Fermi function deconvolution, using the blood pool input function sampled from the left ventricle cavity. MBF and SBF values after performing CPT were significantly higher than rest values (SBF at rest: 0.65 ± 0.15 ml/min/g Vs. SBF after CPT: 0.90 ± 0.14 ml/min/g, p: <0.001; MBF at rest: 0.90 ± 0.068 ml/min/g Vs. MBF after CPT: 1.22 ± 0.098 ml/min/g, p<0.005). Both SBF and MBF increased in all patients during the CPT. In particular, the CPT-induced increase was 43% ± 29% for SBF and 36.5% ± 17% for MBF. CPT increases SBF in normal subjects. The characterization of a standard perfusion response to cold might allow the use of the spleen as reference marker for the adequacy of cold stimulation during myocardial perfusion MRI.

Relation between finger cold-induced vasodilation and rewarming speed after cold exposure

Purpose

The risk for local cold injuries has been linked to poor cold-induced vasodilation (CIVD) during cold exposure and to poor rewarming after cold exposure. The purpose of this study is to establish the relation between CIVD and rewarming speed.

Methods

Twelve participants immersed one hand in ice water for 30 min to evoke CIVD and the other hand in ice water for 10 min to investigate the rewarming profile. The ring, middle and index fingertip temperatures were monitored during hand immersion and the resistance index of frostbite (RIF) was calculated. RIF depends on minimal (T_min) and mean (T_mean) finger skin temperature and onset time. Rewarming was quantified using an infrared imaging system and the rewarming speed over 19 min was determined.

Results

T_min (5.8 ± 3.0 °C) and T_mean (10.4 ± 3.0 °C) caused non-distinctive contributions to the total RIF-scores so that onset time (12.7 ± 3.1 min) became the dominant factor. A significant negative correlation between RIF and rewarming speed was found (r_s = − 0.60, p = 0.041).

Conclusions

The negative relation between RIF and rewarming speed may be explained by the common observation that onset time relates to the temperature of fingertip tissue, while T_min, T_mean and rewarming speed relates to body thermal status. The rewarming test is to be preferred over the CIVD test in terms of ease of use, but the predictive value of the rewarming test for cold injuries is limited, cannot replace the RIF since onset time of finger vasodilation is not included and should be further investigated.

Motor and sensory effects of ipsilesional upper extremity hypothermia and contralesional sensory training for chronic stroke patients

As hypothermia by immersion can reduce the sensory nerve conduction velocity, this study hypothesized that the reduction of sensory input to the ipsilesional upper extremity (UE) using cryotherapy would reduce the inhibitory activity of the contralesional hemisphere in chronic stroke subjects.

OBJECTIVE

In this study, hypothermia was applied by immersing the ipsilesional UE in association with sensory training of the contralesional UE of stroke patients to assess the immediate (e.g. sensorimotor function, hemodynamics, and levels of comfort) and long-term (sensory and motor performances of the UEs) effects.

METHODS

The sample included 27 stroke patients allocated into group 1 (n = 14), which received conventional physiotherapy for the affected UE, and group 2 (n = 13), which underwent 10 sessions of immersion hypothermia of the ipsilesional wrist and hand. Assessments were performed pre- and post-treatment and at follow-up using esthesiometry, the Fugl-Meyer Assessment (FMA), the Nottingham Sensory Assessment, functional tests, tactile and weight discrimination, motor sequence, level of comfort, and hemodynamic parameters.

RESULTS

The immediate effects of hypothermia using immersion of the ipsilesional UE in association with sensory training of the contralesional UE were hemodynamic stability during and after hypothermia, the absence of sensory abnormalities in the contralesional UE, hypoesthesia in the ipsilesional extremity (dermatomes C6 and C8) (P < 0.05), the maintenance of acceptable levels of comfort, and good patient compliance to the technique. The long-term effects included significant increases in scores on tests performed without functional vision, in scores on blindfolded functional tests, and in tactile localization and joint position sense for the contralesional hand in group 2 as well as the maintenance of these gains at long-term follow-up (5 weeks). Improvement was also found in the tactile function of the C6 and C7 dermatomes of the contralesional hand (P < 0.05).

CONCLUSIONS

The use of immersion hypothermia on the ipsilesional UE in association with sensory training of the contralesional UE improved motor function and sensitivity in the contralesional UE of individuals with chronic stroke. Immersion hypothermia of the ipsilesional UE in chronic stroke patients is a safe, practical, inexpensive, and easily applied technique.

Early differential diagnosis of the severity of acute pancreatitis

There is a great need for early verification of the severity of acute pancreatitis (AP). The early stage of pathogenesis of AP is characterized by endothelial dysfunction which could be determined by wavelet analysis of skin temperature (WAST) technique. The aim is to investigate whether the dysregulation of microvascular tone caused by endothelial dysfunction and detected by WAST can be a significant indicator in early differential diagnosis of AP severity. The WAST performed in the frequency range of 0.0095-0.02 Hz during the contralateral cold test. Forty nine patients with AP aged 19-65 participated in this study. The control group included 12 healthy volunteers aged 20-65. Dysregulation of vascular tone during the contralateral cold test was observed in all patients with AP. The basal amplitudes of skin temperature oscillations in patients with AP were much lower than in healthy volunteers and progressively decreased as the disease severity increased. In patients with mild and moderate AP only the vasodilator component is destroyed, but vasoconstriction still operates. In patients with severe AP both mechanisms of endothelial vascular tone regulation are destroyed. Patients with AP have abnormal microvascular reactions related to the endothelial mechanism of vascular tone regulation. Based on the initial values of amplitudes and the indices of vasoconstriction and postcold vasodilatation, the WAST method makes it possible to evaluate two related but different characteristics of the endothelial dysfunction in patients with AP on admission which can be a significant indicator in early differential diagnosis of AP severity.

Relationship of oscillating and average components of laser Doppler flowmetry signal

Signals from laser Doppler flowmeters widely used in intravital studies of skin blood flow include, along with a slowly varying average component, an oscillating part. However, in most clinical studies, pulsations are usually smoothed by data preprocessing and only the mean blood flow is analyzed. To reveal the relationship between average and oscillating perfusion components measured by a laser Doppler flowmeter, we examined the microvascular response to the contralateral cold pressor test recorded at two different sites of the hand: dorsal part of the arm and finger pad. Such a protocol makes it possible to provide a wide range of perfusion. The average perfusion always decreases during cooling, while the oscillating component demonstrates a differently directed response. The wavelet analysis of laser Doppler flowmetry (LDF) signals shows that the pulsatile component is nonlinearly related to the average perfusion. Under low perfusion, the amplitude of pulsations is proportional to its mean value, but, as perfusion increases, the amplitude of pulsations becomes lower. The type of response is defined by the basal perfusion and the degree of vasoconstriction caused by cooling. Interpretation of the results is complicated by the nonlinear transfer function of the LDF device, the contribution of which is studied using artificial examples.

Longer rewarming time in finger cooling test in association with HbA1c level in diabetics

OBJECTIVE

To assess if rewarming time in finger cooling test (FCT) as an indicator of microvascular dysfunction is abnormal in patients with type 2 diabetes mellitus (T2DM).

METHODS

Forty-three T2DM patients and 48 healthy controls with similarly distributed baseline demographic, clinical and laboratory parameters were subjected to FCT involving 60-second index finger immersion into water at 4°C. Finger temperature was measured before FCT (baseline-T), immediately after cooling stimulus (T0), and at one-minute intervals until baseline-T recovery. Temperature decline amplitude was calculated as the difference between T0 and baseline-T, and rewarming time as time elapsed from T0 to baseline-T recovery.

RESULTS

T2DM patients compared with healthy controls had statistically similar baseline-T, significantly larger temperature decline amplitude, significantly lower T0, and significantly longer rewarming time. In T2DM patients, rewarming time positively correlated with T2DM duration (r=0.513, p<0.001) and glycated hemoglobin (HbA1c) level (r=0.446, p=0.003), which also were its independent predictors in multivariate regression analysis.

CONCLUSIONS

Patients with T2DM display abnormal FCT results suggestive of microvascular dysfunction, with T2DM duration and HbA1c level independently predicting rewarming time.

Human Physiology in an Aquatic Environment

Water covers over 70% of the earth, has varying depths and temperatures and contains much of the earth's resources. Head-out water immersion (HOWI) or submersion at various depths (diving) in water of thermoneutral (TN) temperature elicits profound cardiorespiratory, endocrine, and renal responses. The translocation of blood into the thorax and elevation of plasma volume by autotransfusion of fluid from cells to the vascular compartment lead to increased cardiac stroke volume and output and there is a hyperperfusion of some tissues. Pulmonary artery and capillary hydrostatic pressures increase causing a decline in vital capacity with the potential for pulmonary edema. Atrial stretch and increased arterial pressure cause reflex autonomic responses which result in endocrine changes that return plasma volume and arterial pressure to preimmersion levels. Plasma volume is regulated via a reflex diuresis and natriuresis. Hydrostatic pressure also leads to elastic loading of the chest, increasing work of breathing, energy cost, and thus blood flow to respiratory muscles. Decreases in water temperature in HOWI do not affect the cardiac output compared to TN; however, they influence heart rate and the distribution of muscle and fat blood flow. The reduced muscle blood flow results in a reduced maximal oxygen consumption. The properties of water determine the mechanical load and the physiological responses during exercise in water (e.g. swimming and water based activities). Increased hydrostatic pressure caused by submersion does not affect stroke volume; however, progressive bradycardia decreases cardiac output. During submersion, compressed gas must be breathed which introduces the potential for oxygen toxicity, narcosis due to nitrogen, and tissue and vascular gas bubbles during decompression and after may cause pain in joints and the nervous system.

Wrist Hypothermia Related to Continuous Work with a Computer Mouse: A Digital Infrared Imaging Pilot Study

Computer work is characterized by sedentary static workload with low-intensity energy metabolism. The aim of our study was to evaluate the dynamics of skin surface temperature in the hand during prolonged computer mouse work under different ergonomic setups. Digital infrared imaging of the right forearm and wrist was performed during three hours of continuous computer work (measured at the start and every 15 minutes thereafter) in a laboratory with controlled ambient conditions. Four people participated in the study. Three different ergonomic computer mouse setups were tested on three different days (horizontal computer mouse without mouse pad; horizontal computer mouse with mouse pad and padded wrist support; vertical computer mouse without mouse pad). The study revealed a significantly strong negative correlation between the temperature of the dorsal surface of the wrist and time spent working with a computer mouse. Hand skin temperature decreased markedly after one hour of continuous computer mouse work. Vertical computer mouse work preserved more stable and higher temperatures of the wrist (>30 °C), while continuous use of a horizontal mouse for more than two hours caused an extremely low temperature (<28 °C) in distal parts of the hand. The preliminary observational findings indicate the significant effect of the duration and ergonomics of computer mouse work on the development of hand hypothermia.

Abnormal thermography in Parkinson's disease

BACKGROUND

An autonomic denervation and abnormal vasomotor reflex in the skin have been described in Parkinson's disease (PD) and might be evaluable using thermography with cold stress test.

METHODS

A cross-sectional pilot study was undertaken in 35 adults: 15 patients with PD and abnormal [(123)I]-metaiodobenzylguanidine cardiac scintigraphy and 20 healthy controls. Baseline thermography of both hands was obtained before immersing one in cold water (3 ± 1 °C) for 2 min. Continuous thermography was performed in: non-immersed hand (right or with lesser motor involvement) during immersion of the contralateral hand and for 6 min afterward; and contralateral immersed hand for 6 min post-immersion. The region of interest was the dorsal skin of the third finger, distal phalanx.

RESULTS

PD patients showed a lower mean baseline hand temperature (p = 0.037) and greater thermal difference between dorsum of wrist and third finger (p = 0.036) and between hands (p = 0.0001) versus controls, regardless of the motor laterality. Both tests evidenced an adequate capacity to differentiate between groups: in the non-immersed hand, the PD patients did not show the normal cooling pattern or final thermal overshoot observed in controls (F = 5.29; p = 0.001), and there was an AUC of 0.897 (95%CI 0.796-0.998) for this cooling; in the immersed hand, thermal recovery at 6 min post-immersion was lesser in patients (29 ± 17% vs. 55 ± 28%, p = 0.002), with an AUC of 0.810 (95%CI 0.662-0.958).

CONCLUSIONS

PD patients reveal abnormal skin thermal responses in thermography with cold stress test, suggesting cutaneous autonomic dysfunction. This simple technique may be useful to evaluate autonomic dysfunction in PD.

Frequency and temperature dependence of skin bioimpedance during a contralateral cold test

A study of the α- and β-dispersion of skin bioimpedance dependence on temperature and micro-hemodynamics is presented. The vascular tone changes during the cold test are verified by the wavelet-analysis of skin temperature signals obtained simultaneously with impedance measurements. Thirty three normal healthy subjects of 28  ±  7 years old were entered into the study. The tetra-polar electrode system was used to record the resistance and reactance; measurements were carried out at 67 frequencies, in a frequency range from 2 Hz to 50 kHz. It has been found that the impedance decreases with vasodilation and increases with vasoconstriction. The high values of correlation among thermal oscillation amplitudes and Nyquist diagram parameters prove the impedance dependence on blood flow in three frequency bands corresponding to the myogenic, neurogenic and endothelial vascular tone regulation mechanisms. Using an equivalent RC circuit, we obtained the changes in the Nyquist diagram matching the experimental data. The proposed descriptive α-dispersion model can be used to study mechanisms responsible for intercellular interaction.

Assessment of endothelial dysfunction in patients with impaired glucose tolerance during a cold pressor test

The objective of this study is to explore changes in microvascular tone during a contralateral cold pressor test and to compare the results obtained in healthy subjects and in patients with impaired glucose tolerance (IGT) and type 2 diabetes. Low-amplitude fluctuations of skin temperature in the appropriate frequency ranges were used as a characteristic for the mechanism for vascular tone regulation. In total, 13 adults with type 2 diabetes aged 40-67 years and 18 adults with IGT aged 31-60 years participated in this pilot study. The control group included 12 healthy men and women aged 39-60 years. The response to the cold pressor test in patients with type 2 diabetes and with IGT differs essentially from that of healthy subjects in the endothelial frequency range. Endothelial dysfunction occurs in the preclinical stage of diabetes and manifests, in particular, as a disturbance of the endothelial part of vascular tone regulation.

Impact of blood pressure cuff inflation rates on flow-mediated dilatation and contralateral arm response

Flow-mediated dilatation (FMD) is widely used as an index of nitric oxide-mediated vasodilator function, yet its methodology has not been well established. Previous research indicates that a rapid inflation of a blood pressure cuff evokes systemic vasoconstriction, as it was observed even on non-occluded contralateral arm. This would potentially contribute to the variability of FMD readings and complicate the emerging evidence that non-occluded contralateral arm fingertip temperature responses during the FMD procedure may be an indicator of the presence of coronary artery disease. To test the hypotheses that rapid inflation of a blood pressure cuff could reduce FMD values and influence contralateral vasodilatory states, 33 apparently healthy adults (18 males and 15 females, 29±6 years) were studied in two randomized FMD trials. The blood flow-occluding cuff was inflated rapidly (<1 s) in one trial or slowly over 10 s in the other trial. Arterial diameter, fingertip temperature and infrared thermography were obtained throughout each session. FMD values were not different between the rapid and slow cuff inflation trials (5.9±0.6 vs 5.9±0.4%). There were no differences in reactive hyperaemia (6.4±1.6 vs 6.2±1.7 AU), shear stress (80±20 vs 77±17 dyn cm(-2)) and fingertip temperature rebound (TR; 1.8±1.2 vs 1.9±1.0 °C) between the rapid and slow inflation. Changes in finger temperature on the contralateral (non-occluded) arm were positively associated with those on the occluded arm (r=0.26 to 0.61, P<0.05). We concluded that rates of inflating a blood pressure cuff do not affect FMD and TR response, and that neurovascular-induced vasodilatation of the contralateral arm was not observed regardless of cuff inflation rates.