Interactive effect of hypoxia and otolith organ engagement on cardiovascular regulation in humans

2002 ◽  
Vol 93 (2) ◽  
pp. 576-580 ◽  
Author(s):  
Kevin D. Monahan ◽  
Chester A. Ray
Keyword(s):  
Muscle Sympathetic Nerve Activity ◽  
Interactive Effect ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Otolith Organs ◽  
Additive Interaction ◽  
Burst Frequency ◽  
Arterial Blood ◽  
Vestibulosympathetic Reflex ◽  
The Individual

We determined the interaction between the vestibulosympathetic reflex and the arterial chemoreflex in 12 healthy subjects. Subjects performed three trials in which continuous recordings of muscle sympathetic nerve activity (MSNA), mean arterial blood pressure (MAP), heart rate (HR), and arterial oxygen saturation were obtained. First, in prone subjects the otolith organs were engaged by use of head-down rotation (HDR). Second, the arterial chemoreflex was activated by inspiration of hypoxic gas (10% O2 and 90% N2) for 7 min with HDR being performed during minute 6. Third, hypoxia was repeated (15 min) with HDR being performed during minute 14. HDR [means ± SE; increase (Δ)7 ± 1 bursts/min and Δ50 ± 11% for burst frequency and total MSNA, respectively; P < 0.05] and hypoxia (Δ6 ± 2 bursts/min and Δ62 ± 29%; P < 0.05) increased MSNA. Additionally, MSNA increased when HDR was performed during hypoxia (Δ11 ± 2 bursts/min and Δ127 ± 57% change from normoxia; P < 0.05). These increases in MSNA were similar to the algebraic sum of the individual increase in MSNA elicited by HDR and hypoxia (Δ13 ± 1 bursts/min and Δ115 ± 36%). Increases in MAP (Δ3 ± 1 mmHg) and HR (Δ19 ± 1 beats/min) during combined HDR and hypoxia generally were smaller ( P < 0.05) than the algebraic sum of the individual responses (Δ5 ± 1 mmHg and Δ24 ± 2 beats/min for MAP and HR, respectively; P < 0.05). These findings indicate an additive interaction between the vestibulosympathetic reflex and arterial chemoreflex for MSNA. Therefore, it appears that MSNA outputs between the vestibulosympathetic reflex and arterial chemoreflex are independent of one another in humans.

scholarly journals Greater sensitivity of the vestibulosympathetic reflex in the upright posture in humans

2008 ◽  
Vol 105 (1) ◽  
pp. 65-69 ◽  
Author(s):  
Charity L. Sauder ◽  
Timothy O. Leonard ◽  
Chester A. Ray
Keyword(s):  
Prone Position ◽  
Muscle Sympathetic Nerve Activity ◽  
Head Rotation ◽  
Otolith Organs ◽  
Upright Posture ◽  
Burst Frequency ◽  
Arterial Blood ◽  
Vestibulosympathetic Reflex ◽  
Head Up Tilt ◽  
Stimulation Of

Otolith organs have been shown to activate the sympathetic nervous system in the prone position by head-down rotation (HDR) in humans. To date, otolithic stimulation by HDR has not been comprehensively studied in the upright posture. The purpose of the present study was to determine whether otolithic stimulation increases muscle sympathetic nerve activity (MSNA) in the upright posture. It was hypothesized that stimulation of the otolith organs would increase MSNA in the upright posture, despite increased baseline sympathetic activation due to unloading of the baroreceptors. MSNA, arterial blood pressure, heart rate, and degree of head rotation were measured during HDR in 18 volunteers (23 ± 1 yr) in different postures. Study 1 ( n = 11) examined HDR in the prone and sitting positions and study 2 ( n = 7) examined HDR in the prone and 60° head-up tilt positions. Baseline MSNA was 8 ± 4, 15 ± 4, and 33 ± 2 bursts/min for prone, sitting, and head-up tilt, respectively. HDR significantly increased MSNA in the prone (Δ4 ± 1 and Δ105 ± 37% for burst frequency and total activity, respectively), sitting (Δ5 ± 1 and Δ43 ± 12%), and head-up tilt (Δ7 ± 1 and Δ110 ± 41%; P < 0.05). Sensitivity of the vestibulosympathetic reflex (%ΔMSNA/ΔHDR; degree of head rotation) was significantly greater in the sitting and head-up tilt than prone position (prone = 74 ± 22; sitting = 109 ± 30; head-up tilt = 276 ± 103; P < 0.05). These data indicate that stimulation of the otolith organs can mediate increases in MSNA in the upright posture and suggest a greater sensitivity of the vestibulosympathetic reflex in the upright posture in humans.

scholarly journals Melatonin attenuates the vestibulosympathetic but not vestibulocollic reflexes in humans: selective impairment of the utricles

2010 ◽  
Vol 109 (6) ◽  
pp. 1697-1701 ◽  
Author(s):  
Jonathan S. Cook ◽  
Chester A. Ray
Keyword(s):  
Healthy Subjects ◽  
Muscle Sympathetic Nerve Activity ◽  
Vestibular Nuclei ◽  
Time Of Day ◽  
Vestibular Evoked Myogenic Potentials ◽  
Burst Frequency ◽  
Nerve Activity ◽  
Arterial Blood ◽  
Before And After ◽  
Vestibulosympathetic Reflex

Melatonin has been reported to decrease nerve activity of medial vestibular nuclei in the rat and is associated with attenuated muscle sympathetic nerve activity (MSNA) responses to baroreceptor unloading in humans. The purpose of this study was to determine if melatonin alters the vestibulosympathetic reflex (VSR) and vestibulocollic reflex (VCR) in humans. In study 1, MSNA, arterial blood pressure, and heart rate were measured in 12 healthy subjects (28 ± 1 yr; 6 men, 6 women) during head-down rotation (HDR) before and 45 min after ingestion of either melatonin (3 mg) or placebo (sucrose). Subjects returned at least 2 days later at the same time of day to repeat the trial after ingesting the opposite treatment (melatonin or placebo). Melatonin significantly attenuated MSNA responses during HDR compared with placebo (burst frequency Δ 4 ± 1 vs. Δ 7 ± 1 bursts/min, and total MSNA Δ 51 ± 20 and Δ 96 ± 15%, respectively; P < 0.02). In study 2, vestibular evoked myogenic potentials (VEMP) were measured in 10 healthy subjects (26 ± 1 yr; 4 men and 6 women) before and after ingestion of 3 mg melatonin. Melatonin did not alter the timing of the p13 and n23 peaks (pre-melatonin 13.2 ± 0.4 and 21.3 ± 0.6 ms vs. post-melatonin 13.5 ± 0.4 and 21.4 ± 0.7 ms, respectively) or the p13-n23 interpeak amplitudes [pre-melatonin 22.5 ± 4.6 arbitrary units (au) and post-melatonin 22.7 ± 4.6 au]. In summary, melatonin attenuates the VSR and supports the concept that melatonin negatively affects orthostatic tolerance. However, melatonin does not alter the VCR in humans suggesting melatonin's effect on the VSR appears to be mediated by the utricles.

scholarly journals Accuracy of two pulse-oximetry measurements for INTELLiVENT-ASV in mechanically ventilated patients: a prospective observational study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shinshu Katayama ◽  
Jun Shima ◽  
Ken Tonai ◽  
Kansuke Koyama ◽  
Shin Nunomiya
Keyword(s):  
Oxygen Saturation ◽  
Pulse Oximetry ◽  
Prospective Observational Study ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Arterial Blood Gas ◽  
Mechanically Ventilated ◽  
Mechanically Ventilated Patients ◽  
Arterial Blood ◽  
Ventilated Patients

AbstractRecently, maintaining a certain oxygen saturation measured by pulse oximetry (SpO2) range in mechanically ventilated patients was recommended; attaching the INTELLiVENT-ASV to ventilators might be beneficial. We evaluated the SpO2 measurement accuracy of a Nihon Kohden and a Masimo monitor compared to actual arterial oxygen saturation (SaO2). SpO2 was simultaneously measured by a Nihon Kohden and Masimo monitor in patients consecutively admitted to a general intensive care unit and mechanically ventilated. Bland–Altman plots were used to compare measured SpO2 with actual SaO2. One hundred mechanically ventilated patients and 1497 arterial blood gas results were reviewed. Mean SaO2 values, Nihon Kohden SpO2 measurements, and Masimo SpO2 measurements were 95.7%, 96.4%, and 96.9%, respectively. The Nihon Kohden SpO2 measurements were less biased than Masimo measurements; their precision was not significantly different. Nihon Kohden and Masimo SpO2 measurements were not significantly different in the “SaO2 < 94%” group (P = 0.083). In the “94% ≤ SaO2 < 98%” and “SaO2 ≥ 98%” groups, there were significant differences between the Nihon Kohden and Masimo SpO2 measurements (P < 0.0001; P = 0.006; respectively). Therefore, when using automatically controlling oxygenation with INTELLiVENT-ASV in mechanically ventilated patients, the Nihon Kohden SpO2 sensor is preferable.Trial registration UMIN000027671. Registered 7 June 2017.

scholarly journals BIOCHEMICAL STUDIES ON SHOCK

1944 ◽  
Vol 79 (1) ◽  
pp. 9-22 ◽  
Author(s):  
Frank L. Engel ◽  
Helen C. Harrison ◽  
C. N. H. Long
Keyword(s):  
Blood Pressure ◽  
Amino Acids ◽  
Oxygen Saturation ◽  
Hepatic Artery ◽  
Arterial Oxygen Saturation ◽  
Amino Nitrogen ◽  
Arterial Oxygen ◽  
High Positive Correlation ◽  
Peripheral Tissues ◽  
Arterial Blood

1. In a series of rats subjected to hemorrhage and shock a high negative correlation was found between the portal and peripheral venous oxygen saturations and the arterial blood pressure on the one hand, and the blood amino nitrogen levels on the other, and a high positive correlation between the portal and the peripheral oxygen saturations and between each of these and the blood pressure. 2. In five cats subjected to hemorrhage and shock the rise in plasma amino nitrogen and the fall in peripheral and portal venous oxygen saturations were confirmed. Further it was shown that the hepatic vein oxygen saturation falls early in shock while the arterial oxygen saturation showed no alteration except terminally, when it may fall also. 3. Ligation of the hepatic artery in rats did not affect the liver's ability to deaminate amino acids. Hemorrhage in a series of hepatic artery ligated rats did not produce any greater rise in the blood amino nitrogen than a similar hemorrhage in normal rats. The hepatic artery probably cannot compensate to any degree for the decrease in portal blood flow in shock. 4. An operation was devised whereby the viscera and portal circulation of the rat were eliminated and the liver maintained only on its arterial circulation. The ability of such a liver to metabolize amino acids was found to be less than either the normal or the hepatic artery ligated liver and to have very little reserve. 5. On complete occlusion of the circulation to the rat liver this organ was found to resist anoxia up to 45 minutes. With further anoxia irreversible damage to this organ's ability to handle amino acids occurred. 6. It is concluded that the blood amino nitrogen rise during shock results from an increased breakdown of protein in the peripheral tissues, the products of which accumulate either because they do not circulate through the liver at a sufficiently rapid rate or because with continued anoxia intrinsic damage may occur to the hepatic parenchyma so that it cannot dispose of amino acids.

Pulse Oximetry: An Alternative Method for the Assessment of Oxygenation in Newborn Infants

PEDIATRICS ◽  
1987 ◽  
Vol 79 (4) ◽  
pp. 524-528
Author(s):  
Michael S. Jennis ◽  
Joyce L. Peabody
Keyword(s):  
Pulse Oximetry ◽  
Pulse Oximeter ◽  
Arterial Oxygen Saturation ◽  
Newborn Infants ◽  
Fetal Hemoglobin ◽  
Arterial Oxygen ◽  
Skin Injury ◽  
Reliable Technique ◽  
Arterial Blood

Continuous monitoring of oxygenation in sick newborns is vitally important. However, transcutaneous Po2 measurements have a number of limiations. Therefore, we report the use of the pulse oximeter for arterial oxygen saturation (Sao2) determination in 26 infants (birth weights 725 to 4,000 g, gestational ages 24 to 40 weeks, and postnatal ages one to 49 days). Fetal hemoglobin determinations were made on all infants and were repeated following transfusion. Sao2, readings from the pulse oximeter were compared with the Sao2 measured in vitro on simultaneously obtained arterial blood samples. The linear regression equation for 177 paired measurements was: y = 0.7x + 27.2; r = .9. However, the differences between measured Sao2 and the pulse oximeter Sao2 were significantly greater in samples with &gt; 50% fetal hemoglobin when compared with samples with &lt; 25% fetal hemoglobin (P &lt; .001). The pulse oximeter was easy to use, recorded trends in oxygenation instantaneously, and was not associated with skin injury. We conclude that pulse oximetry is a reliable technique for the continuous, noninvasive monitoring of oxygenation in newborn infants.

Saturation of arterial blood with oxygen during maximal exercise

1964 ◽  
Vol 19 (2) ◽  
pp. 284-286 ◽  
Author(s):  
Loring B. Rowell ◽  
Henry L. Taylor ◽  
Yang Wang ◽  
Walter S. Carlson
Keyword(s):  
Oxygen Saturation ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Oxygen Intake ◽  
Arterial Oxygen Content ◽  
Good Physical Condition ◽  
Arterial Blood ◽  
Sedentary Group ◽  
Arterial Desaturation ◽  
Sufficient Intensity

The per cent saturation of the arterial blood with oxygen was examined in four men before and during the last 15 sec of a 3-min run of sufficient intensity to elicit a maximal oxygen intake. The measurements were repeated after a 3-month period of intensive conditioning for middle distance running and in a group of four athletes in good physical condition. The per cent saturation in the sedentary group was 95.8 at rest and 93.4 during exhausting exercise; after conditioning the similar figures were 95.4 and 91.4 and, finally, the athletes showed a per cent saturation of 85.2 during the heavy work. The arterial oxygen content during exhausting work was found to be 20.12 ml/100 ml blood in the sedentary group before training, 19.02 after conditioning, and 18.18 in the group of athletes. It is concluded that, in athletes who are well conditioned and pushing themselves close to the limit of their capacity, arterial desaturation can take place. athletic conditioning and arterial oxygen saturation; arterial desaturation in athletes; ventilation and arterial desaturation; oxygen intake and arterial oxygen saturation Submitted on August 5, 1963

scholarly journals Non-Traditional Administration of Remifentanil in an Experimental Setting

2019 ◽  
pp. S97-S103
Author(s):  
A. KURZOVÁ ◽  
J. MÁLEK ◽  
L. HESS ◽  
M. JAČEK ◽  
J. SLÍVA
Keyword(s):  
Arterial Oxygen Saturation ◽  
Pharmacokinetic Profile ◽  
Rapid Onset ◽  
Arterial Oxygen ◽  
Onset Of Action ◽  
Routes Of Administration ◽  
Arterial Blood ◽  
Pharmacokinetic Properties ◽  
Righting Reflex ◽  
Cardiovascular Functions

Remifentanil is ultrashort-acting opioid with a unique pharmacokinetic profile. It is used exclusively intravenously. While considering its rapid onset of action and other pharmacokinetic properties, we decided to assess its effects following administration via non-traditional routes. Rabbits (n=10 per each group) were randomized into six groups: remifentanil 1 μg/kg and 3 μg/kg IM, 5.0 and 10.0 μg/kg conjunctivally, and 10 μg/kg and 25.0 μg/kg intranasally. Sedating effects were assessed via a loss of the righting reflex. Secondary, mean arterial blood pressure, arterial oxygen saturation of hemoglobin, and pulse rate was monitored in all rabbits. Non-traditional routes of administration were shown to provide a rapid onset of action as well as fast recovery. Importantly, the administration of remifentanil did not result in any deterioration of cardiovascular functions.

Causes of bradycardia with static respiratory hypoxia in athletes

2021 ◽  
Vol 11 (1) ◽  
pp. 30-36
Author(s):  
Yu. E. Vaguine
Keyword(s):  
Heart Rate ◽  
Standard Deviation ◽  
Arterial Oxygen Saturation ◽  
The Other ◽  
Arterial Oxygen ◽  
Breath Holding ◽  
Basketball Players ◽  
Heart Rate Monitor ◽  
Arterial Blood

According to some literature data, during voluntary long-term breath holding (BH), the heart rate (HR) increases, and according to others, it decreases.Objective: to determine the psychophysiological parameters that cause a change in HR during BH in athletes with different resistance to respiratory hypoxia.Materials and methods: HR at BH was studied in 14 beginner athletes, 15 basketball players and 12 swimmers-divers. Duration of BH was recorded. The HR was recorded on a heart rate monitor. After recording an electrocardiogram, the standard deviation of the duration of cardiac cycles was calculated. The arterial oxygen saturation was measured with a pulse oximeter. The statistically significant values of the correlation coefficient (r) were ≥0.33 with p < 0.05.Results: it was found that out of 41 sportsmen, HR increased by more than 5 % in 4, changed insignificantly in 7 and decreased by less than 5 % in 30. Beginner athletes had tachycardia, and BH was quickly interrupted by an imperative inhalation. The saturation of arterial blood with oxygen did not change and did not affect the change in HR. The decrease in heart rate in swimmers-divers in comparison with the other two groups of people examined was statistically significant (p < 0.05). The duration of BH had a direct correlation (r = 0.5) with bradycardia in these people. The duration of BH caused (r = 0.8) hypoxia, the value of which also directly influenced (r = 0.38) the severity of bradycardia. In addition, the decrease in HR depended on high HR (r = 0.36) and low HR variability (r = 0.38) before BH.Conclusion: tachycardia occurs in beginner athletes who experience discomfort with BH. Bradycardia occurs in sportsmen with a long-term BH setting without discomfort. Sympathicotonia in the prelaunch state predetermines the severity of bradycardia in BH. The duration of BH and the resulting hypoxia provide the occurrence of bradycardia.

Pulmonary Effects of Sustained Periods of High-G Acceleration Relevant to Suborbital Spaceflight

2021 ◽  
Vol 92 (8) ◽  
pp. 633-641
Author(s):  
Ross D. Pollock ◽  
Caroline J. Jolley ◽  
Nadia Abid ◽  
John H. Couper ◽  
Luis Estrada-Petrocelli ◽  
...  
Keyword(s):  
Work Of Breathing ◽  
Arterial Oxygen Saturation ◽  
Regional Distribution ◽  
Blood Gases ◽  
Respiratory Physiology ◽  
Arterial Oxygen ◽  
Relative Distribution ◽  
Respiratory Drive ◽  
Impedance Tomography ◽  
Arterial Blood

AbstractBACKGROUND: Members of the public will soon be taking commercial suborbital spaceflights with significant Gx (chest-to-back) acceleration potentially reaching up to 6 Gx. Pulmonary physiology is gravity-dependent and is likely to be affected, which may have clinical implications for medically susceptible individuals.METHODS: During 2-min centrifuge exposures ranging up to 6 Gx, 11 healthy subjects were studied using advanced respiratory techniques. These sustained exposures were intended to allow characterization of the underlying pulmonary response and did not replicate actual suborbital G profiles. Regional distribution of ventilation in the lungs was determined using electrical impedance tomography. Neural respiratory drive (from diaphragm electromyography) and work of breathing (from transdiaphragmatic pressures) were obtained via nasoesophageal catheters. Arterial blood gases were measured in a subset of subjects. Measurements were conducted while breathing air and breathing 15 oxygen to simulate anticipated cabin pressurization conditions.RESULTS: Acceleration caused hypoxemia that worsened with increasing magnitude and duration of Gx. Minimum arterial oxygen saturation at 6 Gx was 86 1 breathing air and 79 1 breathing 15 oxygen. With increasing Gx the alveolar-arterial (A-a) oxygen gradient widened progressively and the relative distribution of ventilation reversed from posterior to anterior lung regions with substantial gas-trapping anteriorly. Severe breathlessness accompanied large progressive increases in work of breathing and neural respiratory drive.DISCUSSION: Sustained high-G acceleration at magnitudes relevant to suborbital flight profoundly affects respiratory physiology. These effects may become clinically important in the most medically susceptible passengers, in whom the potential role of centrifuge-based preflight evaluation requires further investigation.Pollock RD, Jolley CJ, Abid N, Couper JH, Estrada-Petrocelli L, Hodkinson PD, Leonhardt S, Mago-Elliott S, Menden T, Rafferty G, Richmond G, Robbins PA, Ritchie GAD, Segal MJ, Stevenson AT, Tank HD, Smith TG. Pulmonary effects of sustained periods of high-G acceleration relevant to suborbital spaceflight. Aerosp Med Hum Perform. 2021; 92(7):633641.

Comparison of SVO2, SpO2, and clinical parameters with arterial blood gases during ventilatory weaning after cardiac surgery

1994 ◽  
Vol 3 (5) ◽  
pp. 353-355 ◽  
Author(s):  
ML Noll ◽  
JF Byers
Keyword(s):  
Oxygen Saturation ◽  
Respiratory Rate ◽  
Artery Bypass ◽  
Arterial Oxygen Saturation ◽  
Bypass Graft ◽  
Blood Gases ◽  
Arterial Oxygen ◽  
Arterial Blood Gases ◽  
Arterial Blood Gas ◽  
Arterial Blood

Correlations of mixed venous and arterial oxygen saturation, heart rate, respiratory rate, and mean arterial pressure with arterial blood gas variables were computed for 57 sets of data obtained from 30 postoperative coronary artery bypass graft patients who were being weaned from mechanical ventilation. Arterial oxygen saturation and respiratory rate correlated significantly, although moderately, with blood gases.

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