Brain ECF pH and central chemical control of ventilation during anoxia in turtles

The role of changes in brain extracellular fluid [H+] in the control of breathing during anoxia was studied in unanesthetized turtles, Chrysemys scripta. Ventilation, [minute ventilation (VE), tidal volume (VT), and breathing frequency (f)], cerebral extracellular fluid (ECF) pH, and arterial blood gases were measured at 25 degrees C during a 30-min control period (room air), 30 min of anoxia (100% N2 breathing), and 60 min of recovery (room air). ECF pH was measured in the cerebral cortex with a glass microelectrode (1-2 micron tip diam). Large changes in ventilation, ECF [H+], and arterial blood gases were observed. The predominant ventilatory response was an increase in f with a slight increase in VT. A correlation was observed between ECF [H+] and f, which suggested that central chemoreceptor stimulation was involved in the ventilatory response.

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Ventilatory responses of hamsters and rats to hypoxia and hypercapnia

Journal of Applied Physiology ◽

10.1152/jappl.1985.59.6.1955 ◽

1985 ◽

Vol 59 (6) ◽

pp. 1955-1960 ◽

Cited By ~ 41

Author(s):

B. R. Walker ◽

E. M. Adams ◽

N. F. Voelkel

Keyword(s):

Duty Cycle ◽

Minute Ventilation ◽

Natural Habitat ◽

Blood Gases ◽

Atmospheric Conditions ◽

Arterial Blood Gases ◽

Ventilatory Responses ◽

Arterial Blood ◽

Rat Experiments ◽

Fossorial Species

As a fossorial species the hamster differs in its natural habitat from the rat. Experiments were performed to determine possible differences between the ventilatory responses of awake hamsters and rats to acute exposure to hypoxic and hypercapnic environments. Ventilation was measured with the barometric method while the animals were conscious and unrestrained in a sealed plethysmograph. Tidal volume (VT), respiratory frequency (f), and inspiratory (TI) and expiratory (TE) time measurements were made while the animals breathed normoxic (30% O2), hypercapnic (5% CO2), or hypoxic (10% O2) gases. Arterial blood gases were also measured in both species while exposed to each of these atmospheric conditions. During inhalation of normoxic gas, the VT/100 g was greater and f was lower in the hamster than in the rat. Overall minute ventilation (VE/100 g) in the hamster was less than in the rat, which was reflected in the lower PO2 and higher PCO2 of the hamster arterial blood. When exposed to hypercapnia, the hamster increased VE/100 g solely through VT; however, the VE/100 g increase was significantly less than in the rat. In response to hypoxia, the hamster and rat increased VE/100 g by similar amounts; however, the hamster VE/100 g increase was through f alone, whereas the rat increased both VT/100 g and f. Mean airflow rates (VT/TI) were no different in the hamster or rat in each gas environment; therefore most of the ventilatory responses were the result of changes in TI and TE and respiratory duty cycle (TI/TT).

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Stimulation of ventilation in emphysema by passively induced body motion

Journal of Applied Physiology ◽

10.1152/jappl.1962.17.5.771 ◽

1962 ◽

Vol 17 (5) ◽

pp. 771-774 ◽

Cited By ~ 3

Author(s):

Herman F. Froeb

Keyword(s):

Carbon Dioxide ◽

Technical Assistance ◽

Ventilatory Response ◽

Minute Ventilation ◽

Blood Gases ◽

Body Motion ◽

Therapeutic Tool ◽

Arterial Blood ◽

Weak Muscle ◽

Normal Males

The ventilatory stimulation arising from two different forms of passively induced body motion was chosen for study of 14 male emphysematous subjects with hypercapnia and impaired ventilatory response to carbon dioxide. Nine normal males served as controls. The object of the study was to determine whether the stimulus to ventilation from passive body motion was intact in diseased subjects and whether it could serve as a therapeutic tool by bringing about a reduction in blood carbon dioxide. The results revealed that the stimulus to ventilation was mild and comparable in both groups but was associated with two to three times more oxygen per extra liter of minute ventilation in the diseased subjects. There were no significant changes in the arterial blood gases. It was concluded that the stimulus to ventilation from passive body motion arises from weak muscle action and has no therapeutic application in emphysematous subjects as a means of lowering the PaCOCO2. Note: (With the Technical Assistance of Mabel Pearson, Roy Engstrom, Christa McReynolds, and Carol Kennedy) Submitted on March 5, 1962

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Ventilatory response to moderate and severe hypoxia in adult dogs: role of endorphins

Journal of Applied Physiology ◽

10.1152/jappl.1988.65.3.1383 ◽

1988 ◽

Vol 65 (3) ◽

pp. 1383-1388 ◽

Cited By ~ 16

Author(s):

J. I. Schaeffer ◽

G. G. Haddad

Keyword(s):

Ventilatory Response ◽

Minute Ventilation ◽

Severe Hypoxia ◽

Moderate Hypoxia ◽

Arterial Blood Gas ◽

Arterial Blood ◽

Before And After ◽

The Relationship ◽

Arterial Po2

To determine the role of opioids in modulating the ventilatory response to moderate or severe hypoxia, we studied ventilation in six chronically instrumented awake adult dogs during hypoxia before and after naloxone administration. Parenteral naloxone (200 micrograms/kg) significantly increased instantaneous minute ventilation (VT/TT) during severe hypoxia, (inspired O2 fraction = 0.07, arterial PO2 = 28-35 Torr); however, consistent effects during moderate hypoxia (inspired O2 fraction = 0.12, arterial PO2 = 40-47 Torr) could not be demonstrated. Parenteral naloxone increased O2 consumption (VO2) in severe hypoxia as well. Despite significant increases in ventilation post-naloxone during severe hypoxia, arterial blood gas tensions remained the same. Control studies revealed that neither saline nor naloxone produced a respiratory effect during normoxia; also the preservative vehicle of naloxone induced no change in ventilation during severe hypoxia. These data suggest that, in adult dogs, endorphins are released and act to restrain ventilation during severe hypoxia; the relationship between endorphin release and moderate hypoxia is less consistent. The observed increase in ventilation post-naloxone during severe hypoxia is accompanied by an increase in metabolic rate, explaining the isocapnic response.

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Response of newborn lambs to CO-induced hypoxia

Journal of Applied Physiology ◽

10.1152/jappl.1988.64.5.1870 ◽

1988 ◽

Vol 64 (5) ◽

pp. 1870-1877 ◽

Cited By ~ 6

Author(s):

M. A. Bureau ◽

J. L. Carroll ◽

E. Canet

Keyword(s):

Minute Ventilation ◽

Blood Gases ◽

Periodic Breathing ◽

Respiratory Frequency ◽

Gas Mixture ◽

Arterial Blood Gases ◽

Small Shift ◽

Arterial Blood ◽

The Right ◽

Very High

This study was undertaken to measure the neonate's response to CO-induced hypoxia in the first 10 days of life. CO breathing was used to induce hypoxia because CO causes tissue hypoxia with no or minimal chemoreceptor stimulation. An inspired gas mixture of 0.25 to 0.5% CO in air was used to raise the blood carboxyhemoglobin (HbCO) progressively from 0 to 60% over approximately 20 min. The study, conducted in awake conscious lambs aged 2 and 10 days, consisted in measuring the response of ventilation and the change in arterial blood gases during the rise of HbCO. The results showed that the 2- and 10-day-old lambs tolerated very high HbCO levels without an increase in minute ventilation (VE) and without metabolic acidosis. At both ages, HbCO caused no VE change until HbCO levels rose to between 45 and 50% after which the VE change was exponential in some animals but minimal in others. The VE change was brought about by a rise in tidal volume and respiratory frequency. During the period of maturation from 2 to 10 days, there was a small shift to the right in the VE-HbCO response. In the 10-day-old lambs the VE response to high HbCO was greater than that of the 2-day-olds because of the lambs' higher respiratory frequency response. Six of the 10-day-old lambs but only two of the 2-day-old lambs showed a hypoxic tachypnea to HbCO of 55–65%. None of the lambs developed periodic breathing, dysrhythmic breathing, or recurrent apneas with an HbCO level as high as 60%.(ABSTRACT TRUNCATED AT 250 WORDS)

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Arterial blood gases in conscious rats exposed to hypoxia, hypercapnia, or both

Journal of Applied Physiology ◽

10.1152/jappl.1975.38.4.581 ◽

1975 ◽

Vol 38 (4) ◽

pp. 581-587 ◽

Cited By ~ 63

Author(s):

W. E. Pepelko ◽

G. A. Dixon

Keyword(s):

Control Period ◽

Blood Gases ◽

Barometric Pressure ◽

Male Rats ◽

Arterial Blood Gases ◽

Blood Samples ◽

Air Breathing ◽

Breathing Control ◽

Arterial Blood ◽

Caudal Artery

Adult male rats were anesthetized and catheters were implanted in the caudal artery. Soon after recovery from short-lasting anesthesia, a total of 20 groups of six each were individually exposed to five different oxygen levels varying from 21.0 to 9.0% combined with four CO2 levels ranging from 0 to 12.9% at a mean barometric pressure of 744 Torr. Arterial blood samples were collected and analyzed for pH, Po2, and Pco2 before and near the end of 20-min exposures. During an air-breathing control period, pH averaged 7.466 plus or minus 0.020 SD, Paco2 41.2 plus or minus 1.9 Torr and Pao2 91.8 plus or minus 3.5 Torr. During hypoxia, Pao2 levels were similar to that of acutely hypoxic humans. Rats apparently differ from man in that blood buffering is greater, resulting in a higher pH during air breathing and a smaller [H-+] increase with increasing Paco2. Differences between arterial and inspired CO2 were about 10 Torr at 60 and 90 Torr Plco2 and were not influenced by Plo2.

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Cardiac receptors evoke ventilatory response with increased venous PCO2 at constant arterial PCO2

Journal of Applied Physiology ◽

10.1152/jappl.1990.68.1.369 ◽

1990 ◽

Vol 68 (1) ◽

pp. 369-373 ◽

Cited By ~ 4

Author(s):

J. A. Estavillo

Keyword(s):

Gas Flow ◽

Ventilatory Response ◽

Blood Gases ◽

Minute Volume ◽

Arterial Blood Gases ◽

Rapid Reduction ◽

High Co2 ◽

Arterial Blood ◽

Venous Pco2 ◽

Mixed Venous

The effects of elevated venous PCO2 and denervation of the cardiac ventricles on ventilation were studied in 20 anesthetized open-chest unidirectionally ventilated White Leghorn cockerels. Venous PCO2 was increased by insufflating the gut with high CO2 while recording changes in the amplitude of the sternal movements. Arterial blood gases were held constant by unidirectionally ventilating the lungs with gas flows approximately five times the animal's resting minute volume. Insufflating the gut with 90% N2-10% O2 did not change the level of ventilation, whereas with 90% CO2-10% O2 the amplitude of sternal movement increased 500% above that with no gut gas flow. Exchange of N2 for the CO2 was followed by a rapid reduction of ventilatory movements to control levels. Arterial blood gases remained constant during gut gas insufflation, whereas mixed venous PCO2 increased and mixed venous pH decreased when high CO2 was given to the gut. Cutting the middle cardiac nerves, which primarily innervate the ventricles of the heart, reduced the ventilatory response to CO2 gut insufflation by 67%. Sympathetic denervation of the thoracic viscera did not change the responses. It appears that, in the chicken, increasing the mixed venous PCO2 while holding the arterial blood gases constant alters ventilation by an afferent system located in the venous circulation or in the right ventricle which is sensitive to changes in PCO2.

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Role of arterial blood gases, continuous positive airway pressure and ddimers to rule out pulmonary embolism suspected in obese patients

10.1183/13993003.congress-2016.pa2353 ◽

2016 ◽

Author(s):

Ahmed Gharib ◽

Adel Khattab ◽

Bruno Housset ◽

Adel Saeed ◽

Nada Gomaa ◽

...

Keyword(s):

Pulmonary Embolism ◽

Continuous Positive Airway Pressure ◽

Airway Pressure ◽

Positive Airway Pressure ◽

Blood Gases ◽

Obese Patients ◽

Arterial Blood Gases ◽

Arterial Blood ◽

Rule Out

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The Role of Lactate Dehydrogenase (LDH) Compared to Arterial Blood Gases (ABG) in Diagnosing Pneumocystis Carinii Pneumonia (PCP) in HIV/AIDS Patients on Routine Antiretroviral Therapy

International Journal of Research and Review ◽

10.52403/ijrr.20211001 ◽

2021 ◽

Vol 8 (10) ◽

pp. 1-7

Author(s):

Aulia Rahman ◽

Tambar Kembaren ◽

Endang Sembiring

Keyword(s):

Lactate Dehydrogenase ◽

Pneumocystis Carinii Pneumonia ◽

Predictive Value ◽

Pneumocystis Carinii ◽

Blood Gases ◽

Arterial Blood Gases ◽

Aids Patients ◽

Arterial Blood ◽

Hiv Aids

Background: The lungs are one of the primary target organs for HIV disease and a major source of morbidity and mortality, among others, caused by Pneumocystis carinii pneumonia (PCP) or recurrent bacterial pneumonia. In developing countries, the incidence of PCP infection has soared, with high mortality rates ranging from 20% to 80%. The increase in serum LDH plays an important role in determining the severity of the disease. This study aims to determine the role of LDH examination as a diagnostic tool for PCP and Arterial Blood Gases (ABG) in HIV and AIDS patients. Method: This research is an analytical study using an observational diagnostic test design, conducted from November 2020-January 2021 at the HIV Treatment Room at H. Adam Malik Hospital, Medan with 158 subjects. We calculate the value of sensitivity, specificity, positive predictive value, and negative predictive value. Results: 75.3% of the total sample was male, with the highest age group being 30-39 years old (46.2%) 126 samples (79.7%) had CD4 levels 200 cells/mm3, 98 samples (62%) had LDH levels > 500 U/L. In this study, 113 samples (71.5%) fell into the ABG criteria [PaO2] <70 mmHg). LDH has superior sensitivity and specificity value compared to ABG examination. In this case PaO2 or A-A DO2 in diagnosing PCP in HIV-AIDS patients. Conclusion: LDH examination combined with clinical and radiological examinations has good sensitivity and specificity in the diagnosis of PCP. Keywords: HIV, AIDS, Lactate dehydrogenase, PCP.

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Microdialyzed adenosine in nucleus tractus solitarii and ventilatory response to hypoxia in piglets

Journal of Applied Physiology ◽

10.1152/jappl.1995.79.2.405 ◽

1995 ◽

Vol 79 (2) ◽

pp. 405-410 ◽

Cited By ~ 47

Author(s):

S. Yan ◽

A. Laferriere ◽

C. Zhang ◽

I. R. Moss

Keyword(s):

Ventilatory Response ◽

Minute Ventilation ◽

Nucleus Tractus Solitarii ◽

Breathing Frequency ◽

Ultraviolet Detection ◽

Adenosine Release ◽

Biphasic Pattern ◽

Arterial Blood ◽

Spontaneously Breathing ◽

Ventilatory Response To Hypoxia

Levels of adenosine, inosine, and hypoxanthine from the interstitial space at the nucleus tractus solitarii were measured by microdialysis in eight 20- to 25-day-old anesthetized spontaneously breathing piglets. Microdialyzed samples were collected every 30 min for 2 h after the insertion of the probe to ensure stability of purine levels and then during 30 min each of normoxia, hypoxia (10% O2–90% N2), and normoxia. The purines were separated by high-pressure liquid chromatography with ultraviolet detection and quantified at 254-nm wavelength. Tidal volume, breathing frequency, minute ventilation, mean arterial blood pressure, pH, and gas tensions were measured. Compared with control, adenosine levels during hypoxia increased by 40.7 +/- 5.5% and then tended to decline during the recovery from hypoxia, but the levels remained higher than in control. Ventilatory measures exhibited a modest biphasic pattern during hypoxia and resumed control values by 10 min after the removal of the hypoxia. The increased adenosine release during hypoxia provides additional evidence for the possible participation of adenosine in the central suppression of breathing during hypoxia.

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