The Effects of Increasing Plasma Concentrations of Dexmedetomidine in Humans

Background This study determined the responses to increasing plasma concentrations of dexmedetomidine in humans. Methods Ten healthy men (20-27 yr) provided informed consent and were monitored (underwent electrocardiography, measured arterial, central venous [CVP] and pulmonary artery [PAP] pressures, cardiac output, oxygen saturation, end-tidal carbon dioxide [ETCO2], respiration, blood gas, and catecholamines). Hemodynamic measurements, blood sampling, and psychometric, cold pressor, and baroreflex tests were performed at rest and during sequential 40-min intravenous target infusions of dexmedetomidine (0.5, 0.8, 1.2, 2.0, 3.2, 5.0, and 8.0 ng/ml; baroreflex testing only at 0.5 and 0.8 ng/ml). Results The initial dose of dexmedetomidine decreased catecholamines 45-76% and eliminated the norepinephrine increase that was seen during the cold pressor test. Catecholamine suppression persisted in subsequent infusions. The first two doses of dexmedetomidine increased sedation 38 and 65%, and lowered mean arterial pressure by 13%, but did not change central venous pressure or pulmonary artery pressure. Subsequent higher doses increased sedation, all pressures, and calculated vascular resistance, and resulted in significant decreases in heart rate, cardiac output, and stroke volume. Recall and recognition decreased at a dose of more than 0.7 ng/ml. The pain rating and mean arterial pressure increase to cold pressor test progressively diminished as the dexmedetomidine dose increased. The baroreflex heart rate slowing as a result of phenylephrine challenge was potentiated at both doses of dexmedetomidine. Respiratory variables were minimally changed during infusions, whereas acid-base was unchanged. Conclusions Increasing concentrations of dexmedetomidine in humans resulted in progressive increases in sedation and analgesia, decreases in heart rate, cardiac output, and memory. A biphasic (low, then high) dose-response relation for mean arterial pressure, pulmonary arterial pressure, and vascular resistances, and an attenuation of the cold pressor response also were observed.

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Attenuated Cardiovascular Responses to the Cold Pressor Test in Concussed Collegiate Athletes

Journal of Athletic Training ◽

10.4085/1062-6050-573-18 ◽

2020 ◽

Vol 55 (2) ◽

pp. 124-131 ◽

Cited By ~ 2

Author(s):

Blair D. Johnson ◽

James R. Sackett ◽

Zachary J. Schlader ◽

John J. Leddy

Keyword(s):

Heart Rate ◽

Mean Arterial Pressure ◽

Arterial Pressure ◽

Cold Pressor Test ◽

Collegiate Athletes ◽

Cold Pressor ◽

Cardiovascular Responses ◽

Pressor Test ◽

Healthy Control ◽

Peak Increase

Context Cardiovascular responses to the cold pressor test (CPT) provide information regarding sympathetic function. Objective To determine if recently concussed collegiate athletes had blunted cardiovascular responses during the CPT. Design Cross-sectional study. Setting Laboratory. Patients or Other Participants A total of 10 symptomatic concussed collegiate athletes (5 men, 5 women; age = 20 ± 2 years) who were within 7 days of diagnosis and 10 healthy control individuals (5 men, 5 women; age = 24 ± 4 years). Intervention(s) The participants' right hands were submerged in agitated ice water for 120 seconds (CPT). Main Outcome Measure(s) Heart rate and blood pressure were continuously measured and averaged at baseline and every 30 seconds during the CPT. Results Baseline heart rate and mean arterial pressure were not different between groups. Heart rate increased throughout 90 seconds of the CPT (peak increase at 60 seconds = 16 ± 13 beats/min; P < .001) in healthy control participants but remained unchanged in concussed athletes (peak increase at 60 seconds = 7 ± 10 beats/min; P = .08). We observed no differences between groups for the heart rate response (P > .28). Mean arterial pressure was elevated throughout the CPT starting at 30 seconds (5 ± 7 mm Hg; P = .048) in healthy control individuals (peak increase at 120 seconds = 26 ± 9 mm Hg; P < .001). Mean arterial pressure increased in concussed athletes at 90 seconds (8 ± 8 mm Hg; P = .003) and 120 seconds (12 ± 8 mm Hg; P < .001). Healthy control participants had a greater increase in mean arterial pressure starting at 60 seconds (P < .001) and throughout the CPT than concussed athletes (peak difference at 90 seconds = 25 ± 10 mm Hg and 8 ± 8 mm Hg, respectively; P < .001). Conclusions Recently concussed athletes had blunted cardiovascular responses to the CPT, which indicated sympathetic dysfunction.

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Cutaneous Vascular Responses Evoked in the Hand by the Cold Pressor Test and by Mental Arithmetic

Clinical Science ◽

10.1042/cs0790043 ◽

1990 ◽

Vol 79 (1) ◽

pp. 43-50 ◽

Cited By ~ 23

Author(s):

I. Marriott ◽

Janice M. Marshall ◽

E. J. Johns

Keyword(s):

Mean Arterial Pressure ◽

Arterial Pressure ◽

Vascular Resistance ◽

Mental Arithmetic ◽

Cold Pressor Test ◽

Cold Pressor ◽

Pressor Test ◽

Contralateral Hand ◽

The Right ◽

Cutaneous Vascular Resistance

1. Laser Doppler flowmetry has been used to study changes in cutaneous erythrocyte flux produced in the hand (i) on successive immersion of the contralateral hand in water at 20°C (cold test) and then in water at 0–4°C (cold pressor test), and (ii) by mental arithmetic. 2. In 11 subjects, placing the right hand in water at 20°C for 2 min induced a significant decrease in cutaneous erythrocyte flux in the contralateral hand and a significant fall in mean arterial pressure. Cutaneous vascular resistance, calculated as arterial pressure/cutaneous erythrocyte flux, showed no significant change. Thus, the decrease in erythrocyte flux was apparently due to a fall in perfusion pressure. 3. Subsequent immersion of the right hand in water at 0–4°C for 2 min caused a significant decrease in erythrocyte flux in the contralateral hand and a significant rise in mean arterial pressure. It is concluded that the cold pressor response evoked from one hand elicited a substantial reflex vasoconstriction in the skin of the other hand; accordingly, calculated cutaneous vascular resistance increased significantly. 4. Eight subjects performed mental arithmetic for two periods of 2 min separated by a rest period of 2 min. By the end of the second minute of each period of mental arithmetic there was a significant decrease in erythrocyte flux. Mean arterial pressure increased significantly in the first period only, but calculated cutaneous vascular resistance increased in both periods, consistent with cutaneous vasoconstriction. 5. The cold pressor test and mental arithmetic are aversive stimuli that evoke the characteristic pattern of the alerting or defence response which includes splanchnic vasoconstriction and muscle vasodilatation. Previous studies on the cutaneous vascular component of this response have yielded equivocal results. The present study provides firm evidence that it includes cutaneous vasoconstriction, at least in the hand.

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Acute Cardiovascular Effects of Epidural Spinal Cord Stimulation

January 2018 - Pain Physician ◽

10.36076/ppj.2007/10/677 ◽

2007 ◽

Vol 5;10 (9;5) ◽

pp. 677-685

Author(s):

David M. Schultz

Keyword(s):

Blood Pressure ◽

Spinal Cord ◽

Heart Rate ◽

Mean Arterial Pressure ◽

Arterial Pressure ◽

Spinal Cord Stimulation ◽

Statistical Significance ◽

Cold Pressor Test ◽

Cold Pressor ◽

Arterial Blood

Background: Several animal studies support the contention that thoracic spinal cord stimulation (SCS) might decrease arterial blood pressure. Objective: To determine if electrical stimulation of the dorsal spinal cord in humans will lower mean arterial pressure (MAP) and heart rate (HR). Design: Case Series Methods: Ten normotensive subjects that were clinically indicated for SCS testing were studied. Two of the 10 patients who underwent testing were excluded from the analysis because they did not respond to the Cold Pressor Test (CPT). Systolic blood pressure, diastolic blood pressure, and heart rate were measured continuously at the wrist (using the Vasotrac device). SCS was administered with quadripolar leads implanted into the epidural space under fluoroscopic guidance. SCS was randomly performed either in the T1-T2 or T5-T6 region of the spinal cord during normal conditions as well as during transient stress induced by CPT. The CPT was conducted by immersing the non-dominant hand in ice-cold water for 2 minutes. Results: There were moderate decreases in MAP and HR during SCS at the T5-T6 region compared to baseline that did not reach statistical significance. However, SCS at the T1-T2 region tended to increase MAP and HR compared to baseline but the change did not reach statistical significance. Arterial blood pressure was transiently elevated by 9.4 ± 3.8 mmHg using CPT during the control period with SCS turned off and also during SCS at either the T1-T2 region or T5-T6 region of the spinal cord (by 9.2 ± 5 mmHg and 10.7 ± 8.4 mmHg, respectively). During SCS at T5-T6, the CPT significantly increased MAP by 5.9±7.1 mmHg compared to control CPT (SCS off). Conclusion: This study demonstrated that SCS at either the T1-T2 or T5-T6 region did not significantly alter MAP or HR compared to baseline (no SCS). However, during transcient stress (elevated sympathetic tone) induced by CPT, there was a significant increase in MAP and moderate decrease in HR during SCS at T5-T6 region, which is not consistent with previous data in the literature. Acute SCS did not result in adverse cardiovascular responses and proved to be safe. Key words: Spinal cord stimulation, mean arterial pressure, heart rate, cold pressor test

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Sympathetic activation decreases medium-sized arterial compliance in humans

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1994.267.4.h1368 ◽

1994 ◽

Vol 267 (4) ◽

pp. H1368-H1376 ◽

Cited By ~ 52

Author(s):

P. Boutouyrie ◽

P. Lacolley ◽

X. Girerd ◽

L. Beck ◽

M. Safar ◽

...

Keyword(s):

Mean Arterial Pressure ◽

Arterial Pressure ◽

Mental Stress ◽

Diastolic Pressure ◽

Arterial Compliance ◽

Stress Test ◽

Cold Pressor Test ◽

Cold Pressor ◽

Sympathetic Activation ◽

Pressor Test

This study used a precise noninvasive method in normotensive humans to determine the effects of sympathetic activation on arterial compliance. A recently developed, high-resolution echo-tracking system capable of measuring systolic/diastolic variations of arterial diameter was coupled to a Finapres system and used to calculate instantaneous systolic/diastolic pressure-diameter and compliance-pressure curves for a muscular medium-sized artery, the radial artery. Two standardized tests of sympathetic system activation, a cold pressor test (2 min) and a mental stress test (2 min of mental arithmetic), were performed at an interval of 8 days in random order in nine healthy volunteers [30 +/- 9 (SD) yr]. Radial arterial parameters were recorded every 30 s for 9 min, which included 2 min of cold pressor test or mental stress test. During both tests, radial arterial mean diameter did not change despite t he increase in mean arterial pressure (P < 0.001); stroke change in diameter decreased (P < 0.01), whereas pulse pressure increased (P < 0.01). Arterial compliance, calculated for the instantaneous level of mean arterial pressure, decreased significantly (P < 0.01). Compliance (C) calculated at 100 mmHg (C100) was arbitrarily chosen as a reference point for comparing compliance among the different periods of the test. C100 decreased significant (P < 0.05) during both tests (from 2.93 +/- 1.27 to 2.04 +/- 0.94 and from 3.29 +/- 1.73 to 2.63 +/- 1.55 mm2.mmHg-1.10(-3) during mental stress and the cold pressor test, respectively). These results indicate that sympathetic activation is able to decrease radial arterial compliance in healthy subjects. The reduction in arterial compliance probably resulted from complex interactions between changes in distending blood pressure and changes in radial arterial smooth muscle tone.

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Mean arterial pressure and wave reflection during the cold pressor test: the influence of trunk fat

The FASEB Journal ◽

10.1096/fasebj.29.1_supplement.650.3 ◽

2015 ◽

Vol 29 (S1) ◽

Author(s):

Morton Harwood ◽

Travis Wakeham ◽

John Durocher

Keyword(s):

Mean Arterial Pressure ◽

Arterial Pressure ◽

Wave Reflection ◽

Cold Pressor Test ◽

Cold Pressor ◽

Pressor Test

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Effect of Cold Stress and the Cold Pressor Test on Blood Pressure and Heart Rate

International Archives of BioMedical and Clinical Research ◽

10.21276/iabcr.2016.2.2.14 ◽

2016 ◽

Vol 2 (2) ◽

Cited By ~ 1

Author(s):

Hajra Banoo

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Cold Stress ◽

Cold Pressor Test ◽

Cold Pressor ◽

Pressor Test

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Contactless analysis of heart rate variability during cold pressor test using radar interferometry and bidirectional LSTM networks

Scientific Reports ◽

10.1038/s41598-021-81101-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Kilin Shi ◽

Tobias Steigleder ◽

Sven Schellenberger ◽

Fabian Michler ◽

Anke Malessa ◽

...

Keyword(s):

Heart Rate ◽

Heart Rate Variability ◽

Dynamic Change ◽

Cold Pressor Test ◽

Cold Pressor ◽

Contactless Measurement ◽

Pressor Test ◽

Skin Contact ◽

Bidirectional Lstm ◽

Lstm Network

AbstractContactless measurement of heart rate variability (HRV), which reflects changes of the autonomic nervous system (ANS) and provides crucial information on the health status of a person, would provide great benefits for both patients and doctors during prevention and aftercare. However, gold standard devices to record the HRV, such as the electrocardiograph, have the common disadvantage that they need permanent skin contact with the patient. Being connected to a monitoring device by cable reduces the mobility, comfort, and compliance by patients. Here, we present a contactless approach using a 24 GHz Six-Port-based radar system and an LSTM network for radar heart sound segmentation. The best scores are obtained using a two-layer bidirectional LSTM architecture. To verify the performance of the proposed system not only in a static measurement scenario but also during a dynamic change of HRV parameters, a stimulation of the ANS through a cold pressor test is integrated in the study design. A total of 638 minutes of data is gathered from 25 test subjects and is analysed extensively. High F-scores of over 95% are achieved for heartbeat detection. HRV indices such as HF norm are extracted with relative errors around 5%. Our proposed approach is capable to perform contactless and convenient HRV monitoring and is therefore suitable for long-term recordings in clinical environments and home-care scenarios.

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Variability of the haemodynamic responses to laboratory tests employed in assessment of neural cardiovascular regulation in man

Clinical Science ◽

10.1042/cs0690533 ◽

1985 ◽

Vol 69 (5) ◽

pp. 533-540 ◽

Cited By ~ 40

Author(s):

Gianfranco Parati ◽

Guido Pomidossi ◽

Agustin Ramirez ◽

Bruno Cesana ◽

Giuseppe Mancia

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Test Performance ◽

Blood Pressure Response ◽

Cold Pressor Test ◽

Cold Pressor ◽

Cardiovascular Regulation ◽

Pressor Test ◽

Carotid Baroreceptor ◽

Baroreceptor Stimulation

1. In man evaluation of neural cardiovascular regulation makes use of a variety of tests which address the excitatory and reflex inhibitory neural influences that control circulation. Because interpretation of these tests is largely based on the magnitude of the elicited haemodynamic responses, their reproducibility in any given subject is critical. 2. In 39 subjects with continuous blood pressure (intra-arterial catheter) and heart rate monitoring we measured (i) the blood pressure and heart rate rises during hand-grip and cold-pressor test, (ii) the heart rate changes occurring during baroreceptor stimulation and deactivation by injection of phenylephrine and trinitroglycerine, and (iii) the heart rate and blood pressure changes occurring with alteration in carotid baroreceptor activity by a neck chamber. Each test was carefully standardized and performed at 30 min intervals for a total of six times in each subject. 3. The results showed that the responses to any test were clearly different from one another and that this occurred in all subjects studied. For the group as a whole the average response variability (coefficient of variation) ranged from 10.2% for the blood pressure response to carotid baroreceptor stimulation to 44.2% for the heart rate response to cold-pressor test. The variability of the responses was not related to basal blood pressure or heart rate, nor to the temporal sequence of the test performance. 4. Thus tests employed for studying neural cardiovascular control in man produce responses whose reproducibility is limited. This phenomenon may make it more difficult to define the response magnitude typical of each subject, as well as its comparison in different conditions and diseases.

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