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.

Respiratory system

2014 ◽  
Author(s):  
Jeremy Prout ◽  
Tanya Jones ◽  
Daniel Martin
Keyword(s):  
Work Of Breathing ◽  
Blood Gases ◽  
Respiratory Physiology ◽  
Initial Management ◽  
Diffusion Capacity ◽  
Arterial Blood ◽  
System P ◽  
Clinical Scenarios ◽  
The Common ◽  
And Diffusion

This chapter includes a summary of respiratory physiology, respiratory mechanics (pressure-volume relationships and compliance, airway resistance and the work of breathing) and the pulmonary circulation (pulmonary vascular resistance, shunt and lung zones). Measurement of respiratory flow, lung volumes and diffusion capacity is summarized, as well as measurement and interpretation of arterial blood gases. The physics behind capnography and pulse oximetry are explained with abnormalities related to clinical contexts. The common clinical scenarios of respiratory failure and asthma are discussed with initial management and resuscitation.

Arterial blood gases of the domestic hen

1965 ◽  
Vol 208 (4) ◽  
pp. 798-800 ◽  
Author(s):  
Hugo Chiodi ◽  
James W. Terman
Keyword(s):  
Arterial Oxygen Saturation ◽  
Venous Blood ◽  
Blood Gases ◽  
Arterial Oxygen ◽  
Dissociation Curve ◽  
Arterial Blood Gases ◽  
Blood Samples ◽  
Arterial Blood ◽  
The Right ◽  
Domestic Hen

Individual blood samples were collected anaerobically from the brachial arteries of adult White Rock hens and were analyzed for Po2, Pco2, pH, oxygen content and capacity, and CO2 content and capacity. A dissociation curve was constructed from data on equilibration of pooled venous blood. The average arterial oxygen saturation was 90%, the Pco2 was about 32 mm Hg, the Po2 was between 94 and 99 mm Hg, and the pH averaged 7.49. The dissociation curve, as has been shown before, was shifted to the right of most homeothermic species.

Arterial Blood Gases

2014 ◽  
pp. 410-419
Author(s):  
Jeremy B. Richards ◽  
David H. Roberts
Keyword(s):  
Partial Pressure ◽  
Arterial Oxygen Saturation ◽  
Blood Gases ◽  
Altered Mental Status ◽  
Arterial Oxygen ◽  
Acid Base ◽  
Arterial Blood Gas ◽  
Arterial Blood ◽  
Clinical Syndromes ◽  
Acid Base Status

An arterial blood gas (ABG) provides clinically useful information about an individual's acid–base status, the partial pressure of arterial carbon dioxide, the partial pressure of arterial oxygen, and the arterial oxygen saturation. Hypoxia, dyspnea, or suspected acid–base disturbance are clear indications to check an ABG. Altered mental status, critical illness, and acute respiratory distress syndrome (ARDS) are specific clinical syndromes or presentations that warrant checking an ABG. An ABG is helpful in evaluating pulmonary pathophysiology as the presence and severity of hypoxia and/or hypercapnia can be quantified. Because an ABG can rapidly provide information about oxygenation, ventilation, and acid–base status, ABGs are particularly useful and common in the critical care setting.

scholarly journals Laboratory Assessment of Oxygenation in Methemoglobinemia

2005 ◽  
Vol 51 (2) ◽  
pp. 434-444 ◽  
Author(s):  
Shannon Haymond ◽  
Rohit Cariappa ◽  
Charles S Eby ◽  
Mitchell G Scott
Keyword(s):  
Oxygen Saturation ◽  
Pulse Oximetry ◽  
Arterial Oxygen Saturation ◽  
Blood Gases ◽  
Arterial Oxygen ◽  
Case Conference ◽  
Laboratory Assessment ◽  
Arterial Blood ◽  
Hemoglobin Derivative ◽  
Oxygenation Status

Abstract Background: This case conference reviews laboratory methods for assessing oxygenation status: arterial blood gases, pulse oximetry, and CO-oximetry. Caveats of these measurements are discussed in the context of two methemoglobinemia cases. Cases: Case 1 is a woman who presented with increased shortness of breath, productive cough, chest pain, nausea, fever, and cyanosis. CO-oximetry indicated a carboxyhemoglobin (COHb) fraction of 24.9%. She was unresponsive to O2 therapy, and no source of carbon monoxide could be noted. Case 2 is a man who presented with syncope, chest tightness, and signs of cyanosis. His arterial blood was dark brown, and CO-oximetry showed a methemoglobin (MetHb) fraction of 23%. Issues: Oxygen saturation (So2) can be measured by three approaches that are often used interchangeably, although the measured systems are quite different. Pulse oximetry is a noninvasive, spectrophotometric method to determine arterial oxygen saturation (SaO2). CO-oximetry is a more complex and reliable method that measures the concentration of hemoglobin derivatives in the blood from which various quantities such as hemoglobin derivative fractions, total hemoglobin, and saturation are calculated. Blood gas instruments calculate the estimated O2 saturation from empirical equations using pH and Po2 values. In most patients, the results from these methods will be virtually identical, but in cases of increased dyshemoglobin fractions, including methemoglobinemia, it is crucial that the distinctions and limitations of these methods be understood. Conclusions: So2 calculated from pH and Po2 should be interpreted with caution as the algorithms used assume normal O2 affinity, normal 2,3-diphosphoglycerate concentrations, and no dyshemoglobins or hemoglobinopathies. CO-oximeter reports should include the dyshemoglobin fractions in addition to the oxyhemoglobin fraction. In cases of increased MetHb fraction, pulse oximeter values trend toward 85%, underestimating the actual oxygen saturation. Hemoglobin M variants may yield normal MetHb and increased COHb or sulfhemoglobin fractions measured by CO-oximetry.

scholarly journals Effects of an allosteric hemoglobin affinity modulator on arterial blood gases and cardiopulmonary responses during normoxic and hypoxic low-intensity exercise

2020 ◽  
Vol 128 (6) ◽  
pp. 1467-1476
Author(s):  
Glenn M. Stewart ◽  
Steven Chase ◽  
Troy J. Cross ◽  
Courtney M. Wheatley-Guy ◽  
Michael J. Joyner ◽  
...  
Keyword(s):  
Oxygen Saturation ◽  
Partial Pressure ◽  
Arterial Oxygen Saturation ◽  
Oxygen Affinity ◽  
Blood Gases ◽  
Submaximal Exercise ◽  
Arterial Oxygen ◽  
Arterial Blood ◽  
Hemoglobin Oxygen Affinity ◽  
Low Intensity Exercise

In humans, a novel allosteric hemoglobin-oxygen affinity modulator was administered to comprehensively examine the cardiopulmonary consequences of stabilizing a portion of the available hemoglobin in a high-oxygen affinity state during submaximal exercise in normoxia and hypoxia. Oral administration of voxelotor enhanced arterial oxygen saturation during submaximal exercise without altering oxygen consumption and central hemodynamics; however, the partial pressure of arterial carbon dioxide was reduced and the partial pressure of arterial oxygen was increased implying that hyperventilation also contributed to the increase in oxygen saturation. The preservation of arterial oxygen saturation and content was particularly evident during hypoxic submaximal exercise, when arterial desaturation typically occurs, but this did not influence arterial-venous oxygen difference.

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.

scholarly journals Helping students to understand physiological aspects of regional distribution of ventilation in humans: a experience from the electrical impedance tomography

2018 ◽  
Vol 42 (4) ◽  
pp. 655-660
Author(s):  
Marcelo Alcantara Holanda ◽  
Nathalia Parente de Sousa ◽  
Luana Torres Melo ◽  
Liégina Silveira Marinho ◽  
Helder Veras Ribeiro-Filho ◽  
...  
Keyword(s):  
Medical Students ◽  
Electrical Impedance ◽  
Respiratory Mechanics ◽  
Pulmonary Ventilation ◽  
Regional Distribution ◽  
Lung Ventilation ◽  
Respiratory Physiology ◽  
Impedance Tomography ◽  
Lateral Decubitus ◽  
Basic Concepts

Undergraduate biomedical students often have difficulties in understanding basic concepts of respiratory physiology, particularly respiratory mechanics. In this study, we report the use of electrical impedance tomography (EIT) to improve and consolidate the knowledge about physiological aspects of normal regional distribution of ventilation in humans. Initially, we assessed the previous knowledge of a group of medical students ( n = 39) about regional differences in lung ventilation. Thereafter, we recorded the regional distribution of ventilation through surface electrodes on a healthy volunteer adopting four different decubitus positions: supine, prone, and right and left lateral. The recordings clearly showed greater pulmonary ventilation in the dependent lung, mainly in the lateral decubitus. Considering the differences in pulmonary ventilation between right and left lateral decubitus, only 33% of students were able to notice it correctly beforehand. This percentage increased to 84 and 100%, respectively ( P < 0.01), after the results of the ventilation measurements obtained with EIT were examined and discussed. A self-assessment questionnaire showed that students considered the practical activity as an important tool to assist in the understanding of the basic concepts of respiratory mechanics. Experimental demonstration of the physiological variations of regional lung ventilation in volunteers by using EIT is feasible, effective, and stimulating for undergraduate medical students. Therefore, this practical activity may help faculty and students to overcome the challenges in the field of respiratory physiology learning.

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