Effects of Local Warming on the Peripheral Vein Cross-Sectional Area in Children Under Sedation.

PURPOSE: Peripheral venous catheterization is challenging in small children. The local warming technique has been used to increase the peripheral vein cross-sectional area (CSA) and improve the success rate. However, there is limited evidence on the effect of local warming on venous CSA in children under sedation. DESIGN: A pilot randomized controlled trial. METHODS: Eligible children aged 1 to 4 years undergoing ambulatory surgery were enrolled. At the bedside in the ambulatory surgery center, they were routinely sedated with 1 mcg/kg of intranasal dexmedetomidine. Through a computer allocation program, children were randomized into either a control group or a local warming group. Cephalic vein and basilic vein at 1 cm proximal to cubital fossa were scanned with ultrasound to measure venous CSA. Children in the control group received no intervention; those in the local warming group had a prepared hot pack of ~40°C applied to the target area on the arm for 5 minutes. A second ultrasound measurement was undertaken in both groups. FINDINGS: A total of 35 from 40 children were analyzed. Cephalic vein CSA and basilic vein CSA increased significantly vs the first measurement within the local warming group (P < .05 for both) but not in the control group (P > .05 for both). Cephalic vein CSA was significantly different between groups at the second measurement (P < .05) but not at the first measurement (P > .05). Basilic vein CSA was significantly different between groups neither at the first measurement nor at the second measurement (P > .05 for both). The application of local warming resulted in an average of 34% increase (from 4.1 to 5.5 mm2) in cephalic vein CSA and an average of 21% increase (from 4.8 to 5.8 mm2) in basilic vein CSA. CONCLUSIONS: The application of local warming induced mild venodilation in cephalic vein with an increase in CSA by 34% and had little venodilation effect on the basilic vein with an increase in CSA by only 21%.

Correlation of cerebral microvascular circulation with vital signs in cerebral compression and the validity of three concepts: vasodilation, autoregulation, and terminal rise in arterial pressure.

Background: Vasodilation, autoregulation, and rising arterial pressure are three common concepts in cerebral compression, believed to improve cerebral blood flow to maintain the brain's nutrition. However, these concepts are unclear, unproven, and based on assumptions. This study aimed to correlate cerebral circulation with alterations of vital signs and to evaluate the above concepts based on physics and hemodynamics. Methods: Without new animal experiments, a large amount of data: recording of vital signs, long movies of cerebral circulation, and numerous photos of histological examination and microvessels obstruction in cerebral compression in cats was studied, and only partial and preliminary results were reported in 1970. The experiments were supported by an NIH grant for head injury, done before the 1985 Institutional Animal Care and Use Committee requirement. The advent of digital technology facilitated digitizing and stepwise correlating them and evaluating the validity of the above concepts. Results: As cerebral compression increased intracranial pressure (ICP), veins dilated, not arteries, and arterial microvessels obstructed, diminished, and stopped cerebral circulation. Simultaneously, vital signs deteriorated, and pupils became fixed and dilated. There was no evidence for what is believed as autoregulation. Conclusion: In cerebral compression, rising ICP obstructs cerebral arterial microvessels while simultaneously deteriorating vital signs. There is no evidence for dilatation of the arteries; only veins dilate, best-called venodilation. There is no evidence of autoregulation; what occurs is a cerebral compartmental syndrome. The terminal rise of arterial pressure is the hemodynamic result of cerebral circulation cessation, overloading the aorta. None of the concepts benefit the brain's nutrition.

Acute venodilation properties of low-dose intravenous nitroglycerine in pulmonary veno-occlusive disease: a case report.

Background: The use of pulmonary vasodilators for pulmonary arterial hypertension (PAH) has led to a favourable prognosis. In contrast, pulmonary veno-occlusive disease (PVOD) is characterized by the possibility of severe pulmonary oedema after specific PAH therapy. Pulmonary oedema presumably develops in association with pulmonary arterial vasodilation without concomitant pulmonary venodilation. The venous circulation maximally dilates with small amounts of nitroglycerine. Case summary: A 59-year-old woman with advanced PVOD was referred to our hospital. We performed a right heart catheterization after administering combination therapy with selexipag and macitentan, and intravenous nitroglycerine at 0.2 and 0.4 µg/kg/min decreased pulmonary arterial wedge pressure (PAWP) and mean pulmonary arterial pressure (PAP) to minimal levels. The final dose of 1 µg/kg/min yielded an ∼20% decrease in mean PAP and pulmonary vascular resistance (PVR). Discussion: Here, we described the acute effect of intravenous nitroglycerine on PAWP and PVR in a patient with PVOD. This case highlights the venodilation response even in advanced PVOD, suggesting the importance of further research into selective venous dilators as potent therapy.

Levosimendan-induced venodilation is mediated by opening of potassium channels.

Unique vascular responses adhere to the cardiovascular efficacy of the inodilator levosimendan. In particular, selective venodilation appears to explain its clinical benefit during pulmonary hypertension complicated by heart failure with preserved ejection fraction. Vasodilators increase vessel diameter in various parts of the vascular system to different degrees and thereby influence blood pressure, its distribution, and organ perfusion depending on their mechanisms of action. Levosimendan and its long-lived active metabolite OR-1896 mobilize a set of vasodilatory mechanisms, that is, the opening of the ATP-sensitive K+ channels and other K+ channels on top of a highly selective inhibition of the phosphodiesterase III enzyme. A vessel-specific combination of the above vasodilator mechanisms-in concert with cardiac effects and cardiovascular reflex regulations-illustrates the pharmacological profile of levosimendan in various cardiovascular disorders. While levosimendan has been known to be an inotrope, its properties as an activator of ATP-sensitive K+ channels have gone largely ignored with respect to clinical applications. Here, we provide a summary of what is known about the ATP-sensitive K+ channel properties in preclinical studies and now for the first time, its ATP-sensitive K+ channel properties in a clinical trial.

The venodilation effects of tapping versus massaging for venipuncture.

AIM: To compare the effectiveness of tapping and massaging venodilation techniques by evaluating venous cross-sectional area, venous depth, venous palpation score, and questionnaire responses of study participants. METHODS: This study had a quasi-experimental design. Between August 2016 and October 2016, healthy adult volunteers (n = 30, mean ± standard deviation of age: 22.3 ± 2.2 years) were enrolled in this study. Three venodilation techniques were evaluated: the application of a tourniquet (Control Group), the application of a tourniquet and tapping of the participant's forearm (Tapping Group), and the application of a tourniquet and massaging of the participant's forearm (Massage Group). RESULTS: In all three groups, venous cross-sectional areas increased significantly after the application of the venodilation technique. The change ratio of venous cross-sectional area was significantly larger in the Massage Group than in the Control Group. Additionally, 83.3% of the participants selected massaging as their preferred venodilation technique, stating the technique was comfortable and provided a feeling of relief. CONCLUSIONS: No significant differences were observed between the degrees of venodilation that were achieved using the three investigated venodilation techniques. Nonetheless, massaging was deemed the most effective technique after considering the participants' subjective comments.

Duration of Venodilation for Peripheral Intravenous Cannulation, as Induced by a Thermal Stimulus on the Forearm.

BACKGROUND: Application of a thermal stimulus is a common procedure used to promote venodilation for peripheral intravenous cannulation (PIVC); however, the effects of thermal stimulation on the duration of venodilation and skin temperature of the forearm are unclear. AIM: To investigate the duration of venodilation induced by a thermal stimulus on the forearm. METHOD: Healthy female adults ( N = 40) from Japan participated in this study from November to December 2013. A heat pack was warmed to 40°C ± 2°C and placed over the forearm for 15 min. Vein diameter was measured via ultrasound and skin temperature via temperature sensor at six time points: before application of the thermal stimulus and at 1-min intervals for 5 min upon removal of the thermal stimulus. The main outcomes were vein diameter, proportional change in vein diameter, and skin temperature. We calculated proportional change in vein diameter after application of the thermal stimulus using vein diameter before the thermal stimulus to represent 100%. RESULTS: Compared with vein diameter before thermal stimulus, the diameter at each time point after thermal stimulus was significantly increased ( p < .05) as were proportional change in vein diameter ( p < .05) and skin temperature. CONCLUSION: A thermal stimulus of 40°C ± 2°C on the forearm dilated veins significantly for PIVC, and the effect persisted for at least 5 min.