Effect of Almitrine on Hypoxic Ventilatory Drive Measured by Transient and Progressive Isocapnic Hypoxia in Normal Men

1989 ◽  
Vol 77 (4) ◽  
pp. 431-437 ◽  
Author(s):  
M. A. A. Airlie ◽  
D. C. Flenley ◽  
P. M. Warren
Keyword(s):  
Oxygen Saturation ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Controlled Study ◽  
Peripheral Chemoreceptor ◽  
Ventilatory Drive ◽  
The Difference ◽  
Normal Men

1. In a double-blind placebo-controlled study, we have investigated the effect of the peripheral chemoreceptor stimulant drug almitrine bismesylate on hypoxic ventilatory drive (expressed as the slope of the minute ventilation/arterial oxygen saturation relationship in litres min−1 %−1) as measured by both progressive isocapnic hypoxia at rest and transient hypoxia (three breaths of 100% N2) during moderate exercise, in seven normal men, to determine if the ventilatory response to the transient hypoxic stimulus is a more specific measure of peripheral chemoreceptor sensitivity to hypoxia. 2. Hypoxic ventilatory drive measured using progressive isocapnic hypoxia ranged from −0.13 to −2.65 litres min−1 % −1 after placebo and from − 0.20 to − 6.48 litres min−1 %−1 after almitrine. The response was greater after almitrine in six of the seven subjects, and the difference was significant for the whole group (P < 0.05). 3. Hypoxic ventilatory drive measured using transient hypoxia ranged from −0.19 to −1.59 litres min−1 %−1 after placebo and from −0.09 to −1.62 litres min−1 %−1 after almitrine. The response was not consistently greater after almitrine, and the difference was not significant for the group. 4. Difficulties in accurately quantifying a brief rise in minute ventilation after transient hypoxia, particularly in subjects with a low hypoxic ventilatory drive, may have masked small changes in the slope of the minute ventilation/arterial oxygen saturation relationship with this method. However, the significant increase in the response to progressive isocapnic hypoxia after almitrine suggests that the failure to demonstrate an effect using transient hypoxic stimuli was not solely due to between-day variation in hypoxic ventilatory drive or the small numbers of subjects studied. 5. We conclude that, although transient hypoxia avoids any central depression of ventilation that might result from the prolonged hypoxia used in the conventional steady state or progressive isocapnic methods (thereby leading to underestimation of the hypoxic ventilatory drive), the ventilatory response to such transient stimuli is also affected by factors other than peripheral chemoreceptor activity.

Two patterns of daily hypoxic exposure and their effects on measures of chemosensitivity in humans

2007 ◽  
Vol 103 (6) ◽  
pp. 1973-1978 ◽  
Author(s):  
Michael S. Koehle ◽  
A. William Sheel ◽  
William K. Milsom ◽  
Donald C. McKenzie
Keyword(s):  
Oxygen Saturation ◽  
Intermittent Hypoxia ◽  
Ventilatory Response ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Hypoxic Exposure ◽  
Hypoxic Ventilatory Response ◽  
The Third ◽  
Long Duration ◽  
The Mean

The purpose of this study was to compare chemoresponses following two different intermittent hypoxia (IH) protocols in humans. Ten men underwent two 7-day courses of poikilocapnic IH. The long-duration IH (LDIH) protocol consisted of daily 60-min exposures to normobaric 12% O2. The short-duration IH (SDIH) protocol comprised twelve 5-min bouts of 12% O2, separated by 5-min bouts of room air, daily. Isocapnic hypoxic ventilatory response (HVR) was measured daily during the protocol and 1 and 7 days following. Hypercapnic ventilatory response (HCVR) and CO2 threshold and sensitivity (by the modified Read rebreathing technique) were measured on days 1, 8, and 14. Following 7 days of IH, the mean HVR was significantly increased from 0.47 ± 0.07 and 0.47 ± 0.08 to 0.70 ± 0.06 and 0.79 ± 0.06 l·min−1·%SaO2−1 (LDIH and SDIH, respectively), where %SaO2 is percent arterial oxygen saturation. The increase in HVR reached a plateau after the third day. One week post-IH, HVR values were unchanged from baseline. HCVR increased from 3.0 ± 0.4 to 4.0 ± 0.5 l·min−1·mmHg−1. In both the hyperoxic and hypoxic modified Read rebreathing tests, the slope of the CO2/ventilation plot was unchanged by either intervention, but the CO2/ventilation curve shifted to the left following IH. There were no correlations between the changes in response to hypoxia and hypercapnia. There were no significant differences between the two IH protocols for any measures, indicating that comparable changes in chemoreflex control occur with either protocol. These results also suggest that the two methods of measuring CO2 response are not completely concordant and that the changes in CO2 control do not correlate with the increase in the HVR.

Experimental hypoxemia in older and younger healthy men

1961 ◽  
Vol 16 (4) ◽  
pp. 639-640 ◽  
Author(s):  
Ernst Simonson
Keyword(s):  
Oxygen Saturation ◽  
Arterial Oxygen Saturation ◽  
Older Men ◽  
Arterial Oxygen ◽  
Healthy Men ◽  
The Difference

Arterial oxygen saturation was measured by means of an earlobe oximeter in 68 older (mean age 59.5) and 58 younger, (mean age 23.4 years) healthy men while breathing a 10% O2, 90% N2 mixture for a period of 10 min. The drop of the arterial oxygen saturation was more pronounced in the older men, and the difference in reaction was statistically highly significant. Submitted on January 9, 1961

scholarly journals Brain Blood Flow in Andean and Himalayan High-Altitude Populations: Evidence of Different Traits for the Same Environmental Constraint

2010 ◽  
Vol 31 (2) ◽  
pp. 706-714 ◽  
Author(s):  
Gerard FA Jansen ◽  
Buddha Basnyat
Keyword(s):  
Blood Flow ◽  
Oxygen Saturation ◽  
Arterial Oxygen Saturation ◽  
Oxygen Demand ◽  
Arterial Oxygen ◽  
The Tibetan Plateau ◽  
Brain Blood Flow ◽  
Organ Systems ◽  
Andean Altiplano ◽  
The Difference

Humans have populated the Tibetan plateau much longer than the Andean Altiplano. It is thought that the difference in length of occupation of these altitudes has led to different responses to the stress of hypoxia. As such, Andean populations have higher hematocrit levels than Himalayans. In contrast, Himalayans have increased circulation to certain organ systems to meet tissue oxygen demand. In this study, we hypothesize that cerebral blood flow ( CBF) is higher in Himalayans than in Andeans. Using a MEDLINE and EMBASE search, we included 10 studies that investigated CBF in Andeans and Himalayans between 3,658 and 4,330 m altitude. The CBF values were corrected for differences in hematocrit and arterial oxygen saturation. The data of these studies show a mean hematocrit of 50% in Himalayans and 54.1% in Andeans. Arterial oxygen saturation was 86.9% in Andeans and 88.4% in Himalayans. The CBF in Himalayans was slightly elevated compared with sea-level subjects, and was 24% higher compared with Andeans. After correction for hematorit and arterial oxygen saturation, CBF was ~20% higher in Himalayans compared with Andeans. Altered brain metabolism in Andeans, and/or increased nitric oxide availability in Himalayans may have a role to explain this difference in brain blood flow.

scholarly journals Is pulse oximeter a reliable tool for non-critically ill patients with COVID-19?

2021 ◽  
Author(s):  
Aslıhan Gürün Kaya ◽  
Miraç Öz ◽  
İREM AKDEMİR KALKAN ◽  
Ezgi Gülten ◽  
güle AYDIN ◽  
...  
Keyword(s):  
Oxygen Saturation ◽  
Pulse Oximeter ◽  
Lymphocyte Count ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Arterial Blood Gas ◽  
Reactive Protein ◽  
Arterial Blood ◽  
The Difference ◽  
Clinical Conditions

Introduction: Guidelines recommend using a pulse oximeter rather than arterial blood gas (ABG) for COVID-19 patients. However, significant differences can be observed between oxygen saturation measured by pulse oximetry (SpO2) and arterial oxygen saturation (SaO2) in some clinical conditions. We aimed to assess the reliability of pulse oximeter in patients with COVID-19 Methods: We retrospectively reviewed ABG analyses and SpO2 levels measured simultaneously with ABG in patients hospitalized in COVID-19 wards. Results: We categorized total 117 patients into two groups; in whom the difference between SpO2 and SaO2 was 4% (acceptable difference) and >4% (large difference). Large difference group exhibited higher neutrophil count, C-reactive protein, ferritin, fibrinogen, D-dimer and lower lymphocyte count. Multivariate analyses revealed that increased fibrinogen, increased ferritin and decreased lymphocyte count were independent risk factors for large difference between SpO2 and SaO2. The total study group demonstrated the negative bias of 4.02% with the limits of agreement of −9.22% to 1.17%. The bias became significantly higher in patients with higher ferritin, fibrinogen levels and lower lymphocyte count. Conclusion: Pulse oximeters may not be sufficient to assess actual oxygen saturation especially in COVID-19 patients with high ferritin and fibrinogen levels and low lymphocyte count low SpO2 measurements.

Control of breathing in Sherpas at low and high altitude

1980 ◽  
Vol 49 (3) ◽  
pp. 374-379 ◽  
Author(s):  
P. H. Hackett ◽  
J. T. Reeves ◽  
C. D. Reeves ◽  
R. F. Grover ◽  
D. Rennie
Keyword(s):  
High Altitude ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Acute Hypoxia ◽  
Arterial Oxygen Saturation ◽  
Carbon Dioxide Tension ◽  
Arterial Oxygen ◽  
Hypoxic Ventilatory Response ◽  
Oxygen Administration ◽  
End Tidal

Sherpas are well known for their physical performance at extreme altitudes, yet they are reported to have blunted ventilatory responses to acute hypoxia and relative hypoventilation in chronic hypoxia. To examine this paradox, we studied ventilatory control in Sherpas in comparison to that in Westerners at both low and high altitude. At low altitude, 25 Sherpas had higher minute ventilation, higher respiratory frequency, and lower end-tidal carbon dioxide tension than 25 Westerners. The hypoxic ventilatory response of Sherpas was found to be similar to that in Westerners, even though long altitude exposure had blunted the responses of some Sherpas. At high altitude, Sherpas again had higher minute ventilation and a tendency toward higher arterial oxygen saturation than Westerners. Oxygen administration increased ventilation further in Sherpas but decreased ventilation in Westerners. We conclude that Sherpas differ from other high-altitude natives; their hypoxic ventilatory response is not blunted, and they exhibit relative hyperventilation.

Low chemoresponsiveness and inadequate hyperventilation contribute to exercise-induced hypoxemia

1995 ◽  
Vol 79 (2) ◽  
pp. 575-580 ◽  
Author(s):  
C. A. Harms ◽  
J. M. Stager
Keyword(s):  
Oxygen Consumption ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Arterial Oxygen Saturation ◽  
Maximal Oxygen Consumption ◽  
Co2 Production ◽  
Arterial Oxygen ◽  
Ventilatory Parameters ◽  
Exercise Induced ◽  
End Tidal

Is inadequate hyperventilation a cause of the exercise-induced hypoxemia observed in some athletes during intense exercise? If so, is this related to low chemoresponsiveness? To test the hypothesis that exercise-induced hypoxemia, inadequate hyperventilation, and chemoresponsiveness are related, 36 nonsmoking healthy men were divided into hypoxemic (Hyp; n = 13) or normoxemic (Nor; n = 15) groups based on arterial oxygen saturation (SaO2; Hyp < or = 90%, Nor > 92%) observed during maximum O2 uptake (VO2max). Men with intermediate SaO2 values (n = 8) were only included in correlation analysis. Ventilatory parameters were collected at rest, during a treadmill maximal oxygen consumption (VO2max) test, and during a 5-min run at 90% VO2max. Chemoresponsiveness at rest was assessed via hypoxic ventilatory response (HVR) and hypercapnic ventilatory response (HCVR). VO2max was not significantly different between Nor and Hyp. SaO2 was 93.8 +/- 0.9% (Nor) and 87.7 +/- 2.0% (Hyp) at VO2max. End-tidal PO2 and the ratio of minute ventilation to oxygen consumption (VE/VO2) were lower while PETCO2 was higher for Hyp (P < or = 0.01). End-tidal PO2, end-tidal PCO2, and VE/VO2 correlated (P < or = 0.05) to SaO2 (r = 0.84, r = -0.70, r = 0.72, respectively), suggesting that differences in oxygenation were due to differences in ventilation. HVR and HCVR were significantly lower for Hyp. HVR was related to VE/VO2 (r = 0.43), and HCVR was related to the ratio of VE to CO2 production at VO2max (r = 0.61)

Effect of hyperoxia and hypoxia on exercise-induced breathlessness in normal subjects

1988 ◽  
Vol 74 (5) ◽  
pp. 531-537 ◽  
Author(s):  
N. Chronos ◽  
L. Adams ◽  
A. Guz
Keyword(s):  
Oxygen Saturation ◽  
Oxygen Concentration ◽  
Time Course ◽  
Minute Ventilation ◽  
Arterial Oxygen Saturation ◽  
Normal Subjects ◽  
Secondary Response ◽  
Arterial Oxygen ◽  
Air Breathing ◽  
Inspired Oxygen

1. The subjective changes accompanying alterations in inspired oxygen concentration during heavy exercise have been investigated single blind, in normal subjects. 2. In particular, the intensity of the sensation of breathlessness was quantified using a visual analogue scale and changes were compared with those in objective ventilatory measures. 3. Eleven subjects performed three steady-state workload exercise tests on different days and 100% O2, 15% O2 or air were randomly administered for a fixed interval during each test. 4. Compared with air breathing, all subjects felt less breathless during 100% O2 breathing, and ten of them felt more breathless when inspiring 15% O2; these changes were reversed on return to air breathing. 5. During and after 100% O2, the time course of changes in breathlessness was similar to those for ear arterial oxygen saturation and minute ventilation such that it could be a secondary response to either. However, during and after inspiration of 15% O2, changes in breathlessness occurred relatively more quickly than those in ventilation, more closely reflecting changes in oxygen saturation; this suggests that hypoxia, per se, could contribute to the genesis of this sensation. 6. Individual variability in breathlessness responses to exercise and changes in inspired oxygen concentration did not correlate with objective ventilatory changes; neither were changes in breathlessness in the group particularly associated with changes in respiratory frequency or tidal volume.

Ventilatory response to oxygen after eucapnic hypoxia in conscious dogs

1993 ◽  
Vol 74 (4) ◽  
pp. 1916-1920 ◽  
Author(s):  
K. Y. Cao ◽  
M. Berthon-Jones ◽  
C. E. Sullivan ◽  
C. W. Zwillich
Keyword(s):  
Ventilatory Response ◽  
Moving Average ◽  
Minute Ventilation ◽  
Conscious Dogs ◽  
Ventilatory Drive ◽  
Adult Humans ◽  
The Difference ◽  
Arterial O2 Saturation ◽  
Sustained Hypoxia ◽  
Ventilatory Response To Hypoxia

In humans the ventilatory [minute ventilation (VI)] response to sustained hypoxia is biphasic: an initial brisk increase followed by a decline is usually seen. However, in adult dogs, the ventilatory response to a similar stimulus shows no decline. To evaluate if central ventilatory drive is altered by sustained hypoxia, we measured the lowest ventilation (nadir) as the lowest moving average of seven sequential breaths within 200 s after transition to hyperoxia (100% O2) after 3 different exposures: room air, 4-min (brief) eucapnic hypoxia (arterial O2 saturation = approximately 80%), and 12-min (prolonged) eucapnic hypoxia. The nadir hyperoxic VI after brief hypoxia (2.7 +/- 0.2 l/min) was similar to that after room air (2.6 +/- 0.2 l/min; P > 0.05), with both less than prior room air mean VI (P < 0.05). The nadir after prolonged hypoxia (3.5 +/- 0.3 l/min) was significantly greater than that after brief hypoxia (P < 0.05). This suggests that central ventilatory drive increases in conscious dogs after sustained eucapnic hypoxia. The reason for the difference in central ventilatory response to hypoxia between conscious dogs and adult humans is unexplained.

Cardiovascular and ventilatory response to isocapnic hypoxia at sea level and at 5,050 m

1996 ◽  
Vol 80 (5) ◽  
pp. 1724-1730 ◽  
Author(s):  
G. Insalaco ◽  
S. Romano ◽  
A. Salvaggio ◽  
A. Braghiroli ◽  
P. Lanfranchi ◽  
...  
Keyword(s):  
Oxygen Saturation ◽  
Sea Level ◽  
Minute Ventilation ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Ventilatory Responses ◽  
Hypoxic Conditions ◽  
Progressive Hypoxia ◽  
End Tidal ◽  
End Tidal Co2

To assess the effect of chronic hypoxic conditions on ventilatory, heart rate (HR), and blood pressure (BP) responses to acute progressive isocapnic hypoxia, we studied five healthy Caucasian subjects (3 men and 2 women). Each subject performed one rebreathing test at sea level (SL) and two tests at the Pyramid laboratory at Lobuche, Nepal, at the altitude of 5,050 m, 1 day after arrival (HA1) and after 24 days of sojourn (HA2). The effects of progressive isocapnic hypoxia were tested by using a standard rebreathing technique. BP, electrocardiogram, arterial oxygen saturation, airflow and end-tidal CO2 and O2 were recorded. For each subject, the relationships between arterial oxygen saturation and HR, systolic BP and minute ventilation (VE), respectively, were evaluated. At HA1, the majority of subjects showed a significant increase in VE and BP response and a decrease in HR response to progressive isocapnic hypoxia as compared to SL. At HA2, VE and BP responses further increased, whereas the HR response remained similar to that observed at HA1. A significant relationship between hypoxic ventilatory responses and both systolic and diastolic BP responses to progressive hypoxia was found. No significant correlation was found between hypoxic ventilatory and HR responses.

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.

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