Postural variations in dead space and CO2 gradients breathing air and O2

1962 ◽  
Vol 17 (3) ◽  
pp. 417-420 ◽  
Author(s):  
C. P. Larson ◽  
J. W. Severinghaus
Keyword(s):  
Dead Space ◽  
Normal Limit ◽  
Healthy Adult ◽  
Sitting Position ◽  
Alveolar Dead Space ◽  
Vascular Bed ◽  
Postural Changes ◽  
Physiologic Dead Space ◽  
Pulmonary Vascular Bed

Effects of postural changes on anatomic and physiologic dead space and arterial-alveolar CO2gradients were studied in 11 healthy, adult subjects breathing air and O2. Results indicate that, on moving from the supine to the sitting position, Vads and Vpds increased by corresponding amounts (42 and 37 ml) with no increase in alveolar dead space or volume of lung which is nonperfused. Arterial-alveolar CO2 gradients were unaffected by posture, but more than doubled with O2 breathing, suggesting that O2 may relax the pulmonary vascular bed and diminish perfusion of highest lung segments. Isoproterenol aerosol (0.5%) produced significant bronchodilatation (27 ml increase in Vads), but only small and inconsistent increases in alveolar dead space and CO2 gradients. The PDS/Vt ratio in these subjects while sitting, breathing air, averaged 31 ± 6%, which is higher than the normally accepted value of 30%. As a result, the upper normal limit for PDS/Vt has been increased to 40% in our laboratories. Submitted on January 22, 1962

scholarly journals Effects of Pulmonary Vascular Congestion on Postural Changes in the Perfusion and Filling of the Pulmonary Vascular Bed*

1964 ◽  
Vol 43 (1) ◽  
pp. 68-76 ◽  
Author(s):  
Walter J. Daly ◽  
Samuel T. Giammona ◽  
Joseph C. Ross ◽  
Harvey Feigenbaum
Keyword(s):  
Vascular Bed ◽  
Vascular Congestion ◽  
Postural Changes ◽  
Pulmonary Vascular Bed

Effect of posture on pulmonary dead space in man

1959 ◽  
Vol 14 (3) ◽  
pp. 339-344 ◽  
Author(s):  
R. L. Riley ◽  
S. Permutt ◽  
S. Said ◽  
M. Godfrey ◽  
T. O. Cheng ◽  
...  
Keyword(s):  
Tidal Volume ◽  
Dead Space ◽  
Upright Posture ◽  
Alveolar Dead Space ◽  
Erect Posture ◽  
Arterial Blood ◽  
Physiologic Dead Space ◽  
Expired Gas ◽  
The Difference ◽  
Normal Men

Physiologic dead space was determined in the supine and upright postures by simultaneous sampling and subsequent analysis of arterial blood and expired gas for Pco2. In seven normal men there was invariably a higher dead space in the upright than in the supine position. The difference averaged 83 ml and was statistically significant (S.E. 25 ml and P < 0.01). The ratio of dead space to tidal volume also invariably increased on assuming the upright posture. Evidence is presented for believing that most of the change in physiologic dead space resulted from a change in alveolar dead space. Estimated changes in the ratio of alveolar dead space to alveolar tidal volume suggest that approximately one seventh of the total number of alveoli became nonperfused on changing from the supine to the erect posture. These findings are consistent with bronchospirometric and hemodynamic evidence that the apex of the lung is virtually nonperfused in the resting human subject in the upright posture. Submitted on November 12, 1958

Effect of postural changes on intraocular pressure in patients with acute angle-closure glaucoma in Indian population

2020 ◽  
Vol 3 ◽  
pp. 2
Author(s):  
Sanjay Mishra ◽  
Ashok Kumar
Keyword(s):  
Intraocular Pressure ◽  
Acute Angle ◽  
Angle Closure Glaucoma ◽  
Angle Closure ◽  
Sitting Position ◽  
Rebound Tonometer ◽  
Antiglaucoma Medication ◽  
Primary Angle Closure Glaucoma ◽  
Postural Changes ◽  
Healthy Control

Objective: The objective of the study was to compare the posture-induced intraocular pressure (IOP) changes in primary angle-closure glaucoma (PACG) with or without glaucoma medications, and healthy control eyes with normal IOPs in Indian subjects. Materials and Methods: The IOP was measured in the sitting position and the supine position after 10, 20, and 30 min with a rebound tonometer. Results: Twenty-five patients with PACG and 30 controls with normal IOPs were studied. The IOP in the sitting position measured with the rebound tonometer was 13.8 + 3.2 mm Hg in eyes with PAC, and 12.9 + 2.9 mm Hg in eyes with normal IOPs. The IOP increased to 14.4 mm Hg, 16.8 mm Hg, and 18.9 mm Hg at 10 min, 20 min, and 30 min in PACG subjects. In normal age-matched controls, the IOP increased to 13.4 mm Hg, 14.9 mm Hg, and 17.8 mm Hg at 10 min, 20 min, and 30 min, respectively, but none of these differences were significant (P = 0.09; P = 0.08, P = 0.08). The mean postural IOP change from baseline was also not significant between the two groups. Only three patients were on single antiglaucoma medication with well-controlled IOP in the PACG group. Conclusions: Postural IOP changes are comparable among eyes with PACG with and without glaucoma medications, and control eyes.

scholarly journals Intraocular pressure and choroidal thickness postural changes in multiple system atrophy and Parkinson’s disease

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Maddalena De Bernardo ◽  
Giulio Salerno ◽  
Marco Gioia ◽  
Luigi Capasso ◽  
Maria Claudia Russillo ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Intraocular Pressure ◽  
Multiple System Atrophy ◽  
Choroidal Thickness ◽  
Corneal Thickness ◽  
Standing Position ◽  
Sitting Position ◽  
Postural Changes ◽  
Iop Measurement

AbstractTo evaluate intraocular pressure (IOP) and choroidal thickness (ChT) postural changes in multiple system atrophy (MSA), Parkinson’s disease (PD) patients and healthy controls (HC). 20 MSA patients, 21 PD patients and 14 HC, were examined. All subjects underwent a complete examination, including corneal thickness, ChT, IOP and axial length (AL) measurements. IOP measurement was performed in supine, sitting, and standing positions, whereas ChT in sitting and standing positions. Supine to standing IOP variations were significantly higher in MSA vs PD(p = 0.01) and in MSA vs HC (p < 0.0001), whereas no significant differences were observed between PD and HC (p = 0.397). Mean sub-foveal ChT in MSA was 240 ± 92 μm in sitting position, and 215 ± 94 μm in standing position with a significant reduction (p = 0.008). Mean sub-foveal ChT in PD was 258 ± 79 μm in sitting position, and 259 ± 76 μm in standing position (p = 0.887). In HC it was 244 ± 36 μm in sitting position, and 256 ± 37 μm in standing position with a significant increase (p = 0.007). The significant IOP and ChT postural changes can be considered additional hallmarks of autonomic dysfunction in MSA and further studies are needed to consider them as biomarkers in the differential diagnosis with PD.

scholarly journals The Use of Alveolar Dead Space Fraction to Predict Postoperative Outcomes after Pediatric Cardiac Surgery: A Retrospective Study

2021 ◽  
Author(s):  
Imran A. Sayed ◽  
Scott Hagen ◽  
Victoria Rajamanickam ◽  
Petros V. Anagnostopoulos ◽  
Marlowe Eldridge ◽  
...  
Keyword(s):  
Cardiac Surgery ◽  
Retrospective Study ◽  
Dead Space ◽  
Pediatric Cardiac Surgery ◽  
Postoperative Outcomes ◽  
Alveolar Dead Space

Effect of Ligation of Left Pulmonary Artery at Birth on Maturation of Pulmonary Vascular Bed

Respiration ◽  
1962 ◽  
Vol 19 (5) ◽  
pp. 362-369
Author(s):  
Peter E. Pool ◽  
Keith H. Averill ◽  
John H.K. Vogel
Keyword(s):  
Pulmonary Artery ◽  
Left Pulmonary Artery ◽  
Vascular Bed ◽  
Pulmonary Vascular Bed

Responses to L-163,491, a nonpeptide angiotensin II mimic, in the pulmonary vascular bed of the cat

1995 ◽  
Vol 287 (2) ◽  
pp. 163-168 ◽  
Author(s):  
Alan D. Kaye ◽  
Bobby D. Nossaman ◽  
Salah Kivlighn ◽  
Ikhlass N. Ibrahim ◽  
Bracken J. De Witt ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Vascular Bed ◽  
Pulmonary Vascular Bed
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