scholarly journals Cerebral Blood Flow and Cognitive Performance in Postural Tachycardia Syndrome: Insights from Sustained Cognitive Stress Test

2020 ◽  
Vol 9 (24) ◽  
Author(s):  
Rachel Wells ◽  
Varun Malik ◽  
Anthony G. Brooks ◽  
Dominik Linz ◽  
Adrian D. Elliott ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Blood Pressure ◽  
Blood Flow ◽  
Stress Test ◽  
Orthostatic Stress ◽  
Postural Tachycardia Syndrome ◽  
Cognitive Stress ◽  
Postural Tachycardia ◽  
End Tidal Carbon Dioxide ◽  
End Tidal

Background The physiology underlying "brain fog" in the absence of orthostatic stress in postural tachycardia syndrome (POTS) remains poorly understood. Methods and Results We evaluated cognitive and hemodynamic responses (cardiovascular and cerebral: heart rate, blood pressure, end‐tidal carbon dioxide, and cerebral blood flow velocity (CBFv) in the middle cerebral artery at baseline, after initial cognitive testing, and after (30‐minutes duration) prolonged cognitive stress test (PCST) whilst seated; as well as after 5‐minute standing in consecutively enrolled participants with POTS (n=22) and healthy controls (n=18). Symptom severity was quantified with orthostatic hypotensive questionnaire at baseline and end of study. Subjects in POTS and control groups were frequency age‐ and sex‐matched (29±11 versus 28±13 years; 86 versus 72% women, respectively; both P ≥0.4). The CBFv decreased in both groups (condition, P =0.04) following PCST, but a greater reduction in CBFv was observed in the POTS versus control group (−7.8% versus −1.8%; interaction, P =0.038). Notably, the reduced CBFv following PCST in the POTS group was similar to that seen during orthostatic stress (60.0±14.9 versus 60.4±14.8 cm/s). Further, PCST resulted in greater slowing in psychomotor speed (6.1% versus 1.4%, interaction, P =0.027) and a greater increase in symptom scores at study completion (interaction, P <0.001) in the patients with POTS, including increased difficulty with concentration. All other physiologic responses (blood pressure and end‐tidal carbon dioxide) did not differ between groups after PCST (all P >0.05). Conclusions Reduced CBFv and cognitive dysfunction were evident in patients with POTS following prolonged cognitive stress even in the absence of orthostatic stress.

scholarly journals Postural hypocapnic hyperventilation is associated with enhanced peripheral vasoconstriction in postural tachycardia syndrome with normal supine blood flow

2006 ◽  
Vol 291 (2) ◽  
pp. H904-H913 ◽  
Author(s):  
Julian M. Stewart ◽  
Marvin S. Medow ◽  
Neil S. Cherniack ◽  
Benjamin H. Natelson
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Blood Volume ◽  
Peripheral Resistance ◽  
Impedance Plethysmography ◽  
Postural Tachycardia Syndrome ◽  
Peripheral Vasoconstriction ◽  
Postural Tachycardia ◽  
End Tidal

Previous investigations have demonstrated a subset of postural tachycardia syndrome (POTS) patients characterized by normal peripheral resistance and blood volume while supine but thoracic hypovolemia and splanchnic blood pooling while upright secondary to splanchnic hyperemia. Such “normal-flow” POTS patients often demonstrate hypocapnia during orthostatic stress. We studied 20 POTS patients (14–23 yr of age) and compared them with 10 comparably aged healthy volunteers. We measured changes in heart rate, blood pressure, heart rate and blood pressure variability, arm and leg strain-gauge occlusion plethysmography, respiratory impedance plethysmography calibrated against pneumotachography, end-tidal partial pressure of carbon dioxide (PetCO2), and impedance plethysmographic indexes of blood volume and blood flow within the thoracic, splanchnic, pelvic (upper leg), and lower leg regional circulations while supine and during upright tilt to 70°. Ten POTS patients demonstrated significant hyperventilation and hypocapnia (POTSHC) while 10 were normocapnic with minimal increase in postural ventilation, comparable to control. While relative splanchnic hypervolemia and hyperemia occurred in both POTS groups compared with controls, marked enhancement in peripheral vasoconstriction occurred only in POTSHC and was related to thoracic blood flow. Variability indexes suggested enhanced sympathetic activation in POTSHC compared with other subjects. The data suggest enhanced cardiac and peripheral sympathetic excitation in POTSHC.

Caffeine and Cerebral Blood Flow

1983 ◽  
Vol 143 (6) ◽  
pp. 604-608 ◽  
Author(s):  
Roy J. Mathew ◽  
Deborah L. Barr ◽  
Maxine L. Weinman
Keyword(s):  
Carbon Dioxide ◽  
Blood Pressure ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Respiratory Rate ◽  
Regional Cerebral Blood Flow ◽  
Inhalation Technique ◽  
Regional Cerebral Blood ◽  
End Tidal Carbon Dioxide ◽  
End Tidal

SummaryTwo groups of normal volunteers had regional cerebral blood flow (rCBF) measured, by the 133Xenon inhalation technique, before and 30 minutes after 250 mg or 500 mg caffeine given orally. rCBF was measured in a third group of subjects, twice, at a similar interval under identical laboratory conditions. Subjects who received caffeine showed significant decreases in rCBF while the others showed no rCBF change from the first to the second measurement. However, the two caffeine groups did not differ in degrees of rCBF reduction. There were no regional variations in the post-caffeine decrease in cerebral blood flow. The three groups did not show significant changes in end-tidal carbon dioxide, pulse rate, blood pressure, forehead skin temperature and respiratory rate.

Case 67: Ehlers-Danlos Syndrome with Postural Tachycardia Syndrome and Psychogenic Pseudosyncope

2019 ◽  
pp. 349-352
Author(s):  
Peter Novak
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Small Fiber Neuropathy ◽  
Postural Tachycardia Syndrome ◽  
Ehlers Danlos Syndrome ◽  
Postural Tachycardia ◽  
Small Fiber ◽  
Danlos Syndrome

Patient became unresponsive during the first minute of the tilt; she was tachycardic but the blood pressure and cerebral blood flow were stable. Psychogenic pseudosyncope can be superimposed on postural tachycardia syndrome (POTS). Pseudosyncope, small fiber neuropathy, and POTS can be associated with hypermobile Ehlers-Danlos syndrome.

scholarly journals The preponderance of initial orthostatic hypotension in postural tachycardia syndrome

2020 ◽  
Vol 129 (3) ◽  
pp. 459-466
Author(s):  
Julian M. Stewart ◽  
Archana Kota ◽  
Mary Breige O’Donnell-Smith ◽  
Paul Visintainer ◽  
Courtney Terilli ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Heart Rate Variability ◽  
Cerebral Blood Flow ◽  
Orthostatic Hypotension ◽  
Pressure Recovery ◽  
Postural Tachycardia Syndrome ◽  
Postural Tachycardia ◽  
Initial Orthostatic Hypotension

Significant initial orthostatic hypotension (IOH) occurs in ~50% of postural tachycardia syndrome (POTS) patients and 13% of controls. Heart rate and blood pressure recovery are prolonged in IOH sustaining lightheadedness; IOH is more prevalent and severe in POTS. Altered cerebral blood flow and cardiorespiratory regulation are more prevalent in POTS. Altered heart rate variability and baroreflex gain may cause nearly instantaneous lightheadedness in POTS. IOH alone fails to confer a strong probability of POTS.

Phase I Safety Assessment of Intrathecal Neostigmine Methylsulfate in Humans 

1995 ◽  
Vol 82 (2) ◽  
pp. 331-343 ◽  
Author(s):  
David D. Hood ◽  
James C. Eisenach ◽  
Robin Tuttle
Keyword(s):  
Carbon Dioxide ◽  
Blood Pressure ◽  
Heart Rate ◽  
Side Effects ◽  
Healthy Volunteers ◽  
Nausea And Vomiting ◽  
Severe Nausea ◽  
End Tidal Carbon Dioxide ◽  
End Tidal ◽  
Ice Water

Background In dogs, sheep, and rats, spinal neostigmine produces analgesia alone and enhances analgesia from alpha 2-adrenergic agonists. This study assesses side effects and analgesia from intrathecal neostigmine in healthy volunteers. Methods After institutional review board approval and informed consent, 28 healthy volunteers were studied. The first 14 volunteers received neostigmine (50-750 micrograms) through a #19.5 spinal needle followed by insertion of a spinal catheter. The remaining 14 volunteers received neostigmine through a #25 or #27 spinal needle without a catheter. Safety measurements included blood pressure, heart rate, oxyhemoglobin saturation, end-tidal carbon dioxide, neurologic evaluation, and computer tests of vigilance and memory. Analgesia in response to ice water immersion was measured. Results Neostigmine (50 micrograms) through the #19.5 needle did not affect any measured variable. Neostigmine (150 micrograms) caused mild nausea, and 500-750 micrograms caused severe nausea and vomiting. Neostigmine (150-750 micrograms) produced subjective leg weakness, decreased deep tendon reflexes, and sedation. The 750-micrograms dose was associated with anxiety, increased blood pressure and heart rate, and decreased end-tidal carbon dioxide. Neostigmine (100-200 micrograms) in saline, injected through a #25 or #27 needle, caused protracted, severe nausea, and vomiting. This did not occur when dextrose was added to neostigmine. Neostigmine by either method of administration reduced visual analog pain scores to immersion of the foot in ice water. Conclusions The incidence and severity of these adverse events from intrathecal neostigmine appears to be affected by dose, method of administration, and baricity of solution. These effects in humans are consistent with studies in animals. Because no unexpected or dangerous side effects occurred, cautious examination of intrathecal neostigmine alone and in combination with other agents for analgesia is warranted.

Intraabdominal Carbon Dioxide Insufflation in the Pregnant Ewe

1996 ◽  
Vol 85 (6) ◽  
pp. 1395-1402. ◽  
Author(s):  
Antonio M. Cruz ◽  
Lucy C. Southerland ◽  
Tanya Duke ◽  
Hugh G. G. Townsend ◽  
James G. Ferguson ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Blood Flow ◽  
Intraabdominal Pressure ◽  
Control Group ◽  
Uterine Blood Flow ◽  
Carbon Dioxide Insufflation ◽  
Carbon Dioxide Pneumoperitoneum ◽  
Arterial Blood ◽  
End Tidal Carbon Dioxide ◽  
End Tidal

Background Laparoscopic surgical procedures are being performed in pregnant women with increasing frequency. Maternal-fetal physiologic changes occurring during intraabdominal carbon dioxide insufflation are poorly understood, and maternal-fetal safety is of concern during carbon dioxide pneumoperitoneum. A previous pilot study using end-tidal carbon dioxide-guided ventilation resulted in maternal and fetal acidosis and tachycardia during carbon dioxide pneumoperitoneum. Using serial arterial PCO2 to guide ventilation, this study was designed to evaluate maternal-fetal cardiopulmonary status, uterine blood flow, and the intraamniotic pressure effects of intraabdominal carbon dioxide insufflation in singleton pregnant ewes between 120 and 135 days of gestation. Methods In a prospective randomized cross-over study, nine ewes were to receive either abdominal insufflation with carbon dioxide to an intraabdominal pressure of 15 mmHg (n = 9; insufflation group) or receive no insufflation (n = 9; control group). Anesthesia was induced with thiopental and maintained with end-tidal halothane (1 to 1.5 minimum alveolar concentration/100% oxygen). Mechanical ventilation was guided by serial maternal arterial blood gas analysis to maintain PaCO2 between 35 and 40 mmHg. Data from insufflated animals were collected during insufflation (60 min) and after desufflation (30 min). Control group data were collected and matched to similar time intervals for 90 min. Ewes were allowed to recover, and after a rest period (48 h) they were entered in the cross-over study. Results During insufflation there was a significant increase (P &lt; 0.05) in maternal PaCO2 to end-tidal carbon dioxide gradient and minute ventilation, with concomitant decreases in maternal end-tidal carbon dioxide and PaO2. Intraamniotic pressure increased significantly during insufflation. No significant changes were observed in maternal hemodynamic variables, fetal variables, or in uterine blood flow during the study. There were no fetal deaths or preterm labor in any of the animals during the experiment. Conclusions During the 1-h insufflation, a marked increase in PaCO2-to-end-tidal carbon dioxide gradient was observed, suggesting that capnography may be an inadequate guide to ventilation during carbon dioxide pneumoperitoneum in the pregnant patient. No other significant circulatory changes were observed.

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