Video thermography: complex regional pain syndrome in the picture

In this thesis videothermography is developed and evaluated as a diagnostic and monitoring tool in Complex Regional Pain Syndrome type 1 (CRPS1). This work is conducted within four pre- set developmental phases: namely, the initial, potential, monitoring and diagnostic phases. Two main methods of measurement were developed and evaluated, namely: i) static videothermography: recording of a thermographic image of an extremity without application of any disturbing factors on temperature regulation and ii) dynamic videothermography: recordings of a sequence of thermographic images during application of various disturbing effects on temperature regulation of the human body. The recorded thermographic images were analysed by means of various mathematical methods and their additive value in the assessment of CRPS1 was studied

Comparison between pulse wave velocities measured using Complior and measured using Biopac

Arterial stiffness is a reliable prognostic parameter for cardiovascular diseases. The effect of change in arterial stiffness can be measured by the change of the pulse wave velocity (PWV). The Complior system is widely used to measure PWV between the carotid and radial arteries by means of piezoelectric clips placed around the neck and the wrist. The Biopac system is an easier to use alternative that uses ECG and simple optical sensors to measure the PWV between the heart and the fingertips, and thus extends a bit more to the peripheral vasculature compared to the Complior system. The goal of this study was to test under various conditions to what extent these systems provide comparable and correlating values. 25 Healthy volunteers, 20–30 years old, were measured in four sequential position: sitting, lying, standing and sitting. The results showed that the Biopac system measured consistently and significantly lower PWV values than the Complior system, for all positions. Correlation values and Bland–Altman plots showed that despite the difference in PWV magnitudes obtained by the two systems the measurements did agree well. Which implies that as long as the differences in PWV magnitudes are taken into account, either system could be used to measure PWV changes over time. However, when basing diagnosis on absolute PWV values, one should be very much aware of how the PWV was measured and with what system

Pulse transit time as a proxy for vasoconstriction in younger and older adults

Objectives: Changes of vasoconstriction may be measured non-invasively using pulse transit time. This study assessed the sensitivity, test-retest reliability and validity of pulse transit time during vasoconstriction provocation and active standing, and the predictive value of pulse transit time for blood pressure drop. Methods: Fifty-five younger (age 70 years) underwent electrocardiography, wrist and finger photoplethysmography and continuous blood pressure and total peripheral resistance measurements during vasoconstriction provocation using a cold pressor test (21 younger adults), or active stand tests (all other participants). Pulse transit tim

Pulse transit time as a proxy for vasoconstriction in younger and older adults

Objectives: Changes of vasoconstriction may be measured non-invasively using pulse transit time. This study assessed the sensitivity, test-retest reliability and validity of pulse transit time during vasoconstriction provocation and active standing, and the predictive value of pulse transit time for blood pressure drop. Methods: Fifty-five younger (age 70 years) underwent electrocardiography, wrist and finger photoplethysmography and continuous blood pressure and total peripheral resistance measurements during vasoconstriction provocation using a cold pressor test (21 younger adults), or active stand tests (all other participants). Pulse transit tim

Postural change in volunteers: sympathetic tone determines microvascular response to cardiac preload and output increases

Purpose: Microvascular perfusion may be a non-invasive indicator of fluid responsiveness. We aimed to investigate which of the microvascular perfusion parameters truly reflects fluid responsiveness independent of sympathetic reflexes. Methods: Fifteen healthy volunteers underwent a postural change from head up tilt (HUT) to the supine position, diminishing sympathetic tone, followed by a 30° passive leg raising (PLR) with unaltered tone. Prior to and after the postural changes, stroke volume (SV) and cardiac output (CO) were measured, as well as sublingual microcirculatory perfusion (sidestream dark field imaging), skin perfusion, and oxygenation (laser Doppler flowmetry and reflectance spectroscopy). Results: In responders (subjects with >10 % increase in CO), the HUT to supine change increased CO, SV, and pulse pressure, while heart rate, systemic vascular resistance, and mean arterial pressure decreased. Additionally, microvascular flow index, laser Doppler flow, and microvascular hemoglobin oxygen saturation and concentration also increased. Conclusion: When preload and forward flow increase in association with a decrease in sympathetic activity, microvascular blood flow increases in the skin and in the sublingual area. When preload and forward flow increase with little to no change in sympathetic activity, only sublingual functional capillary density increases. Therefore, our results indicate that sublingual functional capillary density is the best pa

Small intra-individual variability of the preejection period justifies the use of pulse transit time as approximation of the vascular transit

Background Vascular transit time (VTT) is the propagation time of a pulse wave through an artery; it is a measure for arterial stiffness. Because reliable non-invasive VTT measurements are difficult, as an alternative we measure pulse transit time (PTT). PTT is defined as the time between the R-wave on electrocardiogram and arrival of the resulting pulse wave in a distal location measured with photoplethysmography (PPG). The time between electrical activation of the ventricles and the resulting pulse wave after opening of the aortic valve is called the pre-ejection period (PEP), a component of PTT. The aim of this study was to estimate the variability of PEP at rest, to establish how accurate PTT is as approximation of VTT. Methods PTT was measured and PEP was assessed with echocardiography (gold standard) in three groups of 20 volunteers: 1) a control group without cardiovascular disease aged 50 years, and 3) a group with cardiovascular risk factors, defined as arterial hypertension, dyslipidemia, kidney failure and diabetes mellitus. Results Per group, the mean PEP was: 1) 58.5 ± 13.0 ms, 2) 52.4 ± 11.9 ms, and 3) 57.6 ± 11.6 ms. However, per individual the standard deviation was much smaller, i.e. 1) 2.0-5.9 ms, 2) 2.8-5.1 ms, and 3) 1.6-12.0 ms, respectively. There was no significant difference in the mean PEP of the 3 groups (p = 0.236). Conclusion In conclusion, the intra-individual variability of PEP is small. A change in PT

Using skin surface temperature to differentiate between complex regional pain syndrome type 1 patients after a fracture and control patients with various complaints after a fracture

OBJECTIVE: In this study, we assessed the validity of skin surface temperature recordings, based on various calculation methods applied to the thermographic data, to diagnose acute complex regional pain syndrome type 1 (CRPS1) fracture patients. METHODS: Thermographic recordings of the palmar/plantar side and dorsal side of both hands or feet were made on CRPS1 patients and in control fracture patients with/without and without complaints similar to CRPS1 (total in the three subgroups = 120) just after removal of plaster. Various calculation methods applied to the thermographic data were compared using receiver operating characteristics analysis to obtain indicators of diagnostic value. RESULTS: There were no significant differences in demographic data and characteristics among the three subgroups. The most pronounced differences among the subgroups were vasomotor signs in the CRPS1 patients. The involved side in CRPS1 patients was often warmer compared with the noninvolved extremity. The difference in temperature between the involved site and the noninvolved extremity in CRPS1 patients significantly differed from the difference in temperature between the contralateral extremities of the two control groups. The largest temperature difference between extremities was found in CRPS1 patients. The difference in temperature recordings comparing the palmar/plantar and dorsal recording was not significant in any group. The sensitivity and specificity varied considerably between the various calculation methods used to calculate temperature difference between extremities. The highest level of sensitivity was 71% and the highest specificity was 64%; the highest positive predictive value reached a value of 35% and the highest negative predictive 84%, with a moderate 0.60 ≥ area under the curve ≤ 0.65. CONCLUSION: The validity of skin surface temperature recordings under resting conditions to discriminate between acute CRPS1 fracture patients and control fracture patients with/without complaints is limited, and only useful as a supplementary diagnostic tool

Comparison of bilateral pulse arrival time before and after induced vasodilation by axillary block

The propagation time of arterial pulse waves provides information about arterial stiffness. Pulse arrival time (PAT) is calculated as the time between the R-wave (ECG) and three reference points on photoplethysmographic (PPG) pulse waves: foot, first derivative and peak. Because large variation in PAT-values between patients exists, measurements of the contra-lateral arm as reference could be a solution. However, anatomical differences between arteries of the arms could introduce an offset of PAT. Furthermore, when arterial stiffness decreases (e.g. after axillary blockade (AxB)) and pulse wave amplitude increases (vasodilation), the pulse waveform can change. The aim of this study was to investigate whether there is a difference between the PAT of both arms and to evaluate the effect of vasodilation after AxB on PAT. ECG and PPG was measured on both hands in 34 patients, starting 2min before the injection of local anaesthetic of an AxB and continuing for a period of 30min after block placement. PAT of the baseline and after AxB were calculated and compared. The mean-PAT of both arms were not significantly different for the three reference points. After AxB, PAT significantly increased for all reference points. PAT can be used for intra-subject comparison