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 < 65 years) and 31 older adults (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).

Small intra-individual variability of the pre-ejection 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).

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.

Increasing accuracy of pulse transit time measurements by automated elimination of distorted photoplethysmography waves.

Photoplethysmography (PPG) is a widely available non-invasive optical technique to visualize pressure pulse waves (PWs). Pulse transit time (PTT) is a physiological parameter that is often derived from calculations on ECG and PPG signals and is based on tightly defined characteristics of the PW shape. PPG signals are sensitive to artefacts.

Effect of heat-induced pain stimuli on pulse transit time and pulse wave amplitude in healthy volunteers.

Pain is commonly assessed subjectively by interpretations of patient behaviour and/or reports from patients. When this is impossible the availability of a quantitative objective pain assessment tool based on objective physiological parameters would greatly benefit clinical practice and research beside the standard self-report tests. Vasoconstriction is one of the physiological responses to pain.

Pathophysiological Mechanisms Involved in Vasomotor Disturbances in Complex Regional Pain Syndrome and Implications for Therapy: A Review.

Complex regional pain syndrome (CRPS) is characterized by continuous pain, disproportional to the initial trauma. It usually spreads to the distal parts of the affected limb. Besides continuing pain, a mix of sensory, sudo- and vasomotor disturbances, motor dysfunction, and trophic changes is responsible for physical complaints.

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.

Diurnal and nocturnal skin temperature regulation in chronic complex regional pain syndrome.

Unlabelled: Skin temperature changes due to vasomotor disturbances are important features of complex regional pain syndrome (CRPS). Because this phenomenon has only been studied under controlled conditions, information on daily circadian variability is lacking. Also, studies in chronic CRPS patients with abnormal posturing, in which coldness of the affected extremity is more common, do not exist.

Technical and radiological image quality comparison of different liquid crystal displays for radiology.

Background: To inform cost-effective decisions in purchasing new medical liquid crystal displays, we compared the image quality in displays made by three manufacturers.

Methods: We recruited 19 radiologists and residents to compare the image quality of four liquid crystal displays, including 3-megapixel Barco(®), Eizo(®), and NEC(®) displays and a 6-megapixel Barco display. The evaluators were blinded to the manufacturers' names.

Rotterdam Advanced Multiple Plate: a novel method to measure cold hyperalgesia and allodynia in freely behaving rodents.

Background: To investigate the pathophysiology of temperature hypersensitivity in neuropathic pain rodent models, it is essential to be able to quantify the phenotype as objective as possible. Current temperature sensitivity measuring paradigms are performed during exposure to external factors, i.e.

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.

Cold-induced vasodilatation following traumatic median or ulnar nerve injury.

Purpose: Peripheral nerve injury of the upper extremity frequently causes changes in the thermoregulatory system of the hands and fingers and leads to reports of cold intolerance. In this study, we aimed to measure the influence of median or ulnar nerve injury on cold-induced vasodilatation (CIVD) during prolonged cooling at low temperatures.

Methods: We tested 12 patients with a median (n = 6) or ulnar (n = 6) injury 4 to 76 months after nerve repair.

Rewarming patterns in hand fracture patients with and without cold intolerance.

Purpose: It is often assumed that cold intolerance is associated with abnormalities in the skin temperature due to changes in the blood flow of the hands. In this study, we determined whether patients with and without cold intolerance after a hand fracture or healthy controls have a diminished rewarming after a cold stimulus.

Methods: The severity of cold intolerance was evaluated using the Cold Intolerance Symptom Severity (CISS) questionnaire.

Neural influence on cold induced vasodilatation using a new set-up for bilateral measurement in the rat hind limb.

Cold induced vasoconstriction (CIVC) is a way for mammals to reduce heat loss in an effort to maintain body core temperature. As blood flow to a cooled extremity is reduced, the amount of body heat lost at the cooled location is minimised. However, when the extremity temperature gets below a certain threshold, Cold induced vasodilatation (CIVD) occurs, a phenomenon that is believed to reduce the risk of local cold injuries.

The effect of perfusion pressure on gastric tissue blood flow in an experimental gastric tube model.

Background: Anastomotic leakage and stricture formation remain an important surgical challenge after esophagectomy with gastric tube reconstruction for cancer of the esophagus. The perfusion of the anastomotic site at the proximal site of the gastric tube depends exclusively on the microcirculation, making it susceptible to hypoperfusion. We hypothesized that increasing the perfusion pressure would improve blood flow at the anastomotic site of the gastric tube.

Inflammatory profile of awake function-controlled craniotomy and craniotomy under general anesthesia.

Background: Surgical stress triggers an inflammatory response and releases mediators into human plasma such as interleukins (ILs). Awake craniotomy and craniotomy performed under general anesthesia may be associated with different levels of stress. Our aim was to investigate whether those procedures cause different inflammatory responses.

No recovery of cold complex regional pain syndrome after transdermal isosorbide dinitrate: a small controlled trial.

The microcirculation appears to be impaired in cold chronic complex regional pain syndrome (CRPS). This double-blind, placebo-controlled, randomized trial investigated the effect of the nitric oxide (NO) donor isosorbide dinitrate (ISDN) on the peripheral blood flow in patients with chronic CRPS. Twenty-four patients received 1% ISDN in Vaseline or a placebo ointment applied to the dorsum of the affected hand four times daily for 10 weeks.

Effect of tadalafil on blood flow, pain, and function in chronic cold complex regional pain syndrome: a randomized controlled trial.

Background: This double-blind, randomized, controlled trial investigated the effect of the phosphodiesterase-5 inhibitor tadalafil on the microcirculation in patients with cold Complex Regional Pain Syndrome (CRPS) in one lower extremity.

Methods: Twenty-four patients received 20 mg tadalafil or placebo daily for 12 weeks. The patients also participated in a physical therapy program.

Six years follow-up of the levels of TNF-alpha and IL-6 in patients with complex regional pain syndrome type 1.

In an earlier study, levels of the proinflammatory cytokines TNF-alpha and IL-6 are higher in blisters fluid from the complex regional pain syndrome type 1 (CRPS1) side obtained at 6 and 30 months (median) after the initial event. The aim of this follow-up study is to determine the involvement of these cytokines in long lasting CRPS1. Twelve CRPS1 patients, with median disease duration of 72 months, participated.

Vasodilative effect of isosorbide dinitrate ointment in complex regional pain syndrome type 1.

Background: In complex regional pain syndrome type 1 (CRPS1) vascular changes occur from the initial, inflammatory event onto the trophic signs during chronicity of the disease, resulting in blood flow disturbances and marked temperature changes. Pharmacotherapeutic treatment is generally inadequate.

Aim: To determine whether local application of the nitric oxide donor isosorbide dinitrate (ISDN) could cause vasodilation and thereby improve tissue blood distribution in the affected extremity.

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.