Asphyxiation, Suffocation,and Neck Pressure Deaths

2020 ◽  
Keyword(s):  
Neck Pressure

Does the menstrual cycle influence the sensitivity of vagally mediated baroreflexes?

2002 ◽  
Vol 102 (6) ◽  
pp. 639-644 ◽  
Author(s):  
William H. COOKE ◽  
David A. LUDWIG ◽  
Paul S. HOGG ◽  
Dwain L. ECKBERG ◽  
Victor A. CONVERTINO
Keyword(s):  
Menstrual Cycle ◽  
Young Women ◽  
Regulatory Mechanisms ◽  
Physiological Changes ◽  
Menstrual Cycles ◽  
Time Points ◽  
Normal Menstrual Cycle ◽  
Cardiac Regulation ◽  
Neck Pressure ◽  
Noradrenaline Levels

The menstrual cycle provokes several physiological changes that could influence autonomic regulatory mechanisms. We studied the carotid-cardiac baroreflex in ten healthy young women on four occasions over the course of their menstrual cycles (days 0-8, 9-14, 15-20 and 21-25). We drew blood during each session for analysis of oestrogen, progesterone and noradrenaline (norepinephrine) levels, and assessed carotid-cardiac baroreflex function by analysing R-R interval responses to graded neck pressure sequences. Oestrogen levels followed a classical two-peak (cubic) response, with elevated levels on days 9-14 and 21-25 compared with days 0-8 and 15-20 (P =0.0032), while progesterone levels increased exponentially from days 9-14 to days 21-25 (P = 0.0063). Noradrenaline levels increased from an average of 137pg/ml during the first three measurement periods to 199pg/ml during days 21-25 (P = 0.0456). Carotid-cardiac baroreflex gain and operational point were not statistically different at any of the time points during the menstrual cycle (P⩾0.18). These findings are consistent with the notion that beat-to-beat vagal-cardiac regulation does not change over the course of the normal menstrual cycle.

Effects of the Application of Neck Pressure by a Collar or Harness on Intraocular Pressure in Dogs

2006 ◽  
Vol 42 (3) ◽  
pp. 207-211 ◽  
Author(s):  
Amy M. Pauli ◽  
Ellison Bentley ◽  
Kathryn A. Diehl ◽  
Paul E. Miller
Keyword(s):  
Intraocular Pressure ◽  
Pressure Measurements ◽  
Neck Pressure

The effect on intraocular pressure (IOP) from dogs pulling against a collar or a harness was evaluated in 51 eyes of 26 dogs. The force each dog generated while pulling against a collar or a harness was measured. Intraocular pressure measurements were obtained during application of corresponding pressures via collars or harnesses. Intraocular pressure increased significantly from baseline when pressure was applied via a collar but not via a harness. Based on the results of the study, dogs with weak or thin corneas, glaucoma, or conditions for which an increase in IOP could be harmful should wear a harness instead of a collar, especially during exercise or activity.

Sympathetic transients caused by abrupt alterations of carotid baroreceptor activity in humans

1982 ◽  
Vol 242 (2) ◽  
pp. H185-H190 ◽  
Author(s):  
B. G. Wallin ◽  
D. L. Eckberg
Keyword(s):  
Sympathetic Activity ◽  
Chamber Pressure ◽  
Reduced Pressure ◽  
Cardiac Responses ◽  
Carotid Baroreceptor ◽  
Sympathetic Responses ◽  
Nerve Muscle ◽  
Neck Pressure ◽  
Pressure Changes ◽  
Neck Chamber

We examined the role of carotid baroreceptors in the short-term modulation of sympathetic outflow to the muscle vascular bed and parasympathetic outflow to the heart in 10 healthy adults. Afferent carotid baroreceptor activity was modified with 30-mmHg neck suction or pressure applied during held expiration, and efferent sympathetic activity was measured with microelectrodes inserted percutaneously into peroneal nerve muscle fascicles. Sympathetic responses were conditioned importantly by directional changes of carotid transmural pressure: increased pressure (onset of neck suction or offset of neck pressure) inhibited (totally) sympathetic activity, and reduced pressure (offset of neck suction or onset of neck pressure) augmented sympathetic activity. Responses occurred after a latency of about 2 s and did not persist as long as changes of neck-chamber pressure. Cardiac intervals were prolonged by increased carotid transmural pressures and shortened by decreased carotid transmural pressures, but, in contrast to sympathetic responses, cardiac responses adapted only slightly during neck-chamber pressure changes. Our results suggest that in the human a common baroreceptor input is processed differently in central vagal and sympathetic networks. Muscle sympathetic responses to changing levels of afferent baroreceptor traffic are profound but transitory. They appear to be conditioned more by changes of arterial pressure than by its absolute levels.

Differential baroreflex modulation of human vagal and sympathetic activity

1991 ◽  
Vol 260 (3) ◽  
pp. R635-R641 ◽  
Author(s):  
J. M. Fritsch ◽  
M. L. Smith ◽  
D. T. Simmons ◽  
D. L. Eckberg
Keyword(s):  
Sympathetic Activity ◽  
Peroneal Nerve ◽  
Pressure Step ◽  
Cardiac Responses ◽  
Baroreceptor Stimulation ◽  
Baseline Levels ◽  
Neck Pressure ◽  
Aortic Baroreceptors ◽  
Muscle Responses ◽  
Ambient Levels

We compared baroreflex modulation of human vagal-cardiac and sympathetic muscle activity in healthy volunteers by measuring R-R interval and peroneal nerve responses to a profile of positive and negative (40-65 mmHg) R-wave-triggered neck pressure steps during held expiration. R-R interval responses were sigmoid. Sympathetic activity increased abruptly with 40 mmHg pressure but returned to baseline levels as this pressure was maintained. The first decremental pressure step reduced sympathetic activity to below baseline, and the next three steps inhibited activity. During the final three steps, sympathetic activity increased to baseline, and after the return of neck pressure to ambient levels sympathetic activity increased to the highest levels recorded. Our results suggest that on a second-by-second basis human vagal-cardiac responses are determined simply by the net level of baroreceptor stimulation. Sympathetic muscle responses are determined complexly by the direction of changes (rising or falling) more than absolute arterial pressure levels and importantly by inputs from both carotid and aortic baroreceptors.

scholarly journals Carotid baroreflex control of heart rate is enhanced, while control of mean arterial pressure is preserved during whole body heat stress in young healthy men

2016 ◽  
Vol 311 (4) ◽  
pp. R735-R741 ◽  
Author(s):  
Davor Krnjajic ◽  
Dustin R. Allen ◽  
Cory L. Butts ◽  
David M. Keller
Keyword(s):  
Heart Rate ◽  
Heat Stress ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Whole Body ◽  
Chamber Pressure ◽  
Carotid Baroreflex ◽  
Whole Body Heat Stress ◽  
Neck Pressure ◽  
Body Heat

Whole body heat stress (WBH) results in numerous cardiovascular alterations that ultimately reduce orthostatic tolerance. While impaired carotid baroreflex (CBR) function during WBH has been reported as a potential reason for this decrement, study design considerations may limit interpretation of previous findings. We sought to test the hypothesis that CBR function is unaltered during WBH. CBR function was assessed in 10 healthy male subjects (age: 26 ± 3; height: 185 ± 7 cm; weight: 82 ± 10 kg; BMI: 24 ± 3 kg/m2; means ± SD) using 5-s trials of neck pressure (+45, +30, and +15 Torr) and neck suction (−20, −40, −60, and −80 Torr) during normothermia (NT) and passive WBH (Δ core temp ∼1°C). Analyses of stimulus response curves (four-parameter logistic model) for CBR control of heart rate (CBR-HR) and mean arterial pressure (CBR-MAP), as well as separate two-way ANOVA of the hypotensive and hypertensive stimuli (factor 1: thermal condition, factor 2: chamber pressure), were performed. For CBR-HR, maximal gain was increased during WBH (−0.73 ± 0.11) compared with NT (−0.39 ± 0.04, mean ± SE, P = 0.03). In addition, the CBR-HR responding range was increased during WBH (33 ± 5) compared with NT (19 ± 2 bpm, P = 0.03). Separate analysis of hypertensive stimulation revealed enhanced HR responses during WBH at −40, −60, and −80 Torr (condition × chamber pressure interaction, P = 0.049) compared with NT. For CBR-MAP, both logistic analysis and separate two-way ANOVA revealed no differences during WBH. Therefore, in response to passive WBH, CBR control of heart rate (enhanced) and arterial pressure (no change) is well preserved.

Carotid baroreflex regulation of sympathetic nerve activity during dynamic exercise in humans

2001 ◽  
Vol 280 (3) ◽  
pp. H1383-H1390 ◽  
Author(s):  
P. J. Fadel ◽  
S. Ogoh ◽  
D. E. Watenpaugh ◽  
W. Wasmund ◽  
A. Olivencia-Yurvati ◽  
...  
Keyword(s):  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Dynamic Exercise ◽  
Moderate Intensity ◽  
Burst Frequency ◽  
Nerve Activity ◽  
Arm Cycling ◽  
Carotid Baroreflex ◽  
Neck Pressure

We sought to determine whether carotid baroreflex (CBR) control of muscle sympathetic nerve activity (MSNA) was altered during dynamic exercise. In five men and three women, 23.8 ± 0.7 (SE) yr of age, CBR function was evaluated at rest and during 20 min of arm cycling at 50% peak O2uptake using 5-s periods of neck pressure and neck suction. From rest to steady-state arm cycling, mean arterial pressure (MAP) was significantly increased from 90.0 ± 2.7 to 118.7 ± 3.6 mmHg and MSNA burst frequency (microneurography at the peroneal nerve) was elevated by 51 ± 14% ( P < 0.01). However, despite the marked increases in MAP and MSNA during exercise, CBR-Δ%MSNA responses elicited by the application of various levels of neck pressure and neck suction ranging from +45 to −80 Torr were not significantly different from those at rest. Furthermore, estimated baroreflex sensitivity for the control of MSNA at rest was the same as during exercise ( P = 0.74) across the range of neck chamber pressures. Thus CBR control of sympathetic nerve activity appears to be preserved during moderate-intensity dynamic exercise.

scholarly journals Carotid baroreflex control of arterial blood pressure at rest and during dynamic exercise in aging humans

2010 ◽  
Vol 299 (5) ◽  
pp. R1241-R1247 ◽  
Author(s):  
James P. Fisher ◽  
Areum Kim ◽  
Colin N. Young ◽  
Paul J. Fadel
Keyword(s):  
Blood Pressure ◽  
Response Curve ◽  
Dynamic Exercise ◽  
Baroreflex Control ◽  
Stimulus Response ◽  
Arterial Blood ◽  
Carotid Baroreflex ◽  
Older Subjects ◽  
Maximal Gain ◽  
Neck Pressure

The arterial baroreflex is fundamental for evoking and maintaining appropriate cardiovascular adjustments to exercise. We sought to investigate how aging influences carotid baroreflex regulation of blood pressure (BP) during dynamic exercise. BP and heart rate (HR) were continuously recorded at rest and during leg cycling performed at 50% HR reserve in 15 young (22 ± 1 yr) and 11 older (61 ± 2 yr) healthy subjects. Five-second pulses of neck pressure and neck suction from +40 to −80 Torr were applied to determine the full carotid baroreflex stimulus response curve and examine baroreflex resetting during exercise. Although the maximal gain of the modeled stimulus response curve was similar in both groups at rest and during exercise, in older subjects the operating point (OP) was located further away from the centering point (CP) and toward the reflex threshold, both at rest (OP minus CP; −10 ± 3 older vs. 0 ± 2 young mmHg, P < 0.05) and during exercise (OP minus CP; −10 ± 2 older vs. 1 ± 3 young mmHg, P < 0.05). In agreement, older subjects demonstrated a reduced BP response to neck pressure (simulated carotid hypotension) and a greater BP response to neck suction (simulated carotid hypertension). In addition, the magnitude of the upward and rightward resetting of the carotid baroreflex-BP stimulus response curve with exercise was ∼40% greater in older individuals. These data indicate that despite a maintained maximal gain, the ability of the carotid baroreflex to defend against a hypotensive challenge is reduced, whereas responses to hypertensive stimuli are greater with advanced age, both at rest and during exercise.

scholarly journals Haemodynamic changes during neck pressure and suction in seated and supine positions

2002 ◽  
Vol 540 (2) ◽  
pp. 707-716 ◽  
Author(s):  
S. Ogoh ◽  
P. J. Fadel ◽  
F. Monteiro ◽  
W. L. Wasmund ◽  
P. B. Raven
Keyword(s):  
Haemodynamic Changes ◽  
Neck Pressure

scholarly journals NECK PRESSURE AND SHORTNESS OF BREATH, IT IS TIME TO CALL THE SURGEON

2014 ◽  
Vol 63 (12) ◽  
pp. A682
Author(s):  
M Chadi Alraies ◽  
Hirad Yarmohammadi ◽  
Wael AlJaroudi ◽  
Allan Klein
Keyword(s):  
Shortness Of Breath ◽  
Neck Pressure

scholarly journals Sacral magnetic stimulation in puborectalis paradoxical syndrome

2002 ◽  
Vol 49 (2) ◽  
pp. 27-32 ◽  
Author(s):  
A. Shafik
Keyword(s):  
Magnetic Stimulation ◽  
Pressure Rise ◽  
Canine Model ◽  
Outpatient Basis ◽  
Rectal Balloon ◽  
Balloon Expulsion ◽  
Rectal Pressure ◽  
Balloon Expulsion Test ◽  
Neck Pressure ◽  
Rectal Neck

Background and Purpose: Our earlier studies have demonstrated that sacral magnetic stimulation (IMS) in the canine model, in healthy volunteers and in constipated subjects effected rectal pressure rise, decline of the rectal neck (anal canal) pressure as well as rectal evacuation. Based on these results, we studied the effect of sacral MS on defecation in patients with puborectalis paradoxical syndrome (PPS). Methods: Eleven subjects (8 women, 3 men; age 36-53 years) with PPS were enrolled in the study. The magnetic coil was placed on the back with its center located between L4 and L5. Stimulation parameters were set at 70% of maximum intensity, 40 Hz frequency and 2-second burst length with 2 seconds off. During MS, the rectal neck and gastric (intra-abdominal) pressures were measured. The procedure was performed in the empty and in the full rectum using the balloon expulsion test in the latter. Results: MS of the empty and balloon-filled rectum effected rise of the rectal pressure (p<0.001), decline of the rectal neck pressure (p>0.001) and no significant change of the intragastric pressure (p>0.05). The balloon was expelled to the exterior in all the patients. Conclusions: Sacral MS succeeded in dispelling to the exterior the water-filled rectal balloon. The method is simple, easy, non-invasive, non-radiologic and can be performed on an outpatient basis for the treatment of PPS.

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