Atrial distension in humans during microgravity induced by parabolic flights

1997 ◽  
Vol 83 (6) ◽  
pp. 1862-1866 ◽  
Author(s):  
Regitze Videbaek ◽  
Peter Norsk
Keyword(s):  
Central Venous Pressure ◽  
Left Atrium ◽  
Supine Position ◽  
Left Atrial ◽  
Venous Pressure ◽  
Esophageal Pressure ◽  
Central Venous ◽  
Parabolic Flights ◽  
Left Atrial Diameter ◽  
Cardiac Filling

Videbaek, Regitze, and Peter Norsk. Atrial distension in humans during microgravity induced by parabolic flights. J. Appl. Physiol. 83(6): 1862–1866, 1997.—The hypothesis was tested that human cardiac filling pressures increase and the left atrium is distended during 20-s periods of microgravity (μG) created by parabolic flights, compared with values of the 1-G supine position. Left atrial diameter ( n = 8, echocardiography) increased significantly during μG from 26.8 ± 1.2 to 30.4 ± 0.7 mm ( P < 0.05). Simultaneously, central venous pressure (CVP; n = 6, transducer-tipped catheter) decreased from 5.8 ± 1.5 to 4.5 ± 1.1 mmHg ( P < 0.05), and esophageal pressure (EP; n = 6) decreased from 1.5 ± 1.6 to −4.1 ± 1.7 mmHg ( P < 0.05). Thus transmural CVP (TCVP = CVP − EP; n = 4) increased during μG from 6.1 ± 3.2 to 10.4 ± 2.7 mmHg ( P < 0.05). It is concluded that short periods of μG during parabolic flights induce an increase in TCVP and left atrial diameter in humans, compared with the results obtained in the 1-G horizontal supine position, despite a decrease in CVP.

Arterial pressure in humans during weightlessness induced by parabolic flights

1999 ◽  
Vol 87 (3) ◽  
pp. 928-932 ◽  
Author(s):  
Bettina Pump ◽  
Regitze Videbæk ◽  
Anders Gabrielsen ◽  
Peter Norsk
Keyword(s):  
Arterial Pressure ◽  
Left Atrial ◽  
Venous Pressure ◽  
Lateral Position ◽  
Central Venous ◽  
Short Term ◽  
Parabolic Flights ◽  
Left Atrial Diameter ◽  
Left Lateral Position ◽  
Peripheral Vasodilatation

Results from our laboratory have indicated that, compared with those of the 1-G supine (Sup) position, left atrial diameter (LAD) and transmural central venous pressure increase in humans during weightlessness (0 G) induced by parabolic flights (R. Videbæk and P. Norsk. J. Appl. Physiol. 83: 1862–1866, 1997). Therefore, because cardiopulmonary low-pressure receptors are stimulated during 0 G, the hypothesis was tested that mean arterial pressure (MAP) in humans decreases during 0 G to values below those of the 1-G Sup condition. When the subjects were Sup, 0 G induced a decrease in MAP from 93 ± 4 to 88 ± 4 mmHg ( P< 0.001), and LAD increased from 30 ± 1 to 33 ± 1 mm ( P < 0.001). In the seated position, MAP also decreased from 93 ± 6 to 87 ± 5 mmHg ( P < 0.01) and LAD increased from 28 ± 1 to 32 ± 1 mm ( P < 0.001). During 1-G conditions with subjects in the horizontal left lateral position, LAD increased compared with that of Sup ( P < 0.001) with no further effects of 0 G. In conclusion, MAP decreases during short-term weightlessness to below that of 1-G Sup simultaneously with an increase in LAD. Therefore, distension of the heart and associated central vessels during 0 G might induce the hypotensive effects through peripheral vasodilatation. Furthermore, the left lateral position in humans could constitute a simulation model of weightlessness.

Effect of thoracic duct drainage on hydrostatic pulmonary edema and pleural effusion in sheep

1991 ◽  
Vol 71 (1) ◽  
pp. 314-316 ◽  
Author(s):  
S. J. Allen ◽  
R. E. Drake ◽  
G. A. Laine ◽  
J. C. Gabel
Keyword(s):  
Pleural Effusion ◽  
Central Venous Pressure ◽  
Pulmonary Edema ◽  
Thoracic Duct ◽  
Left Atrial ◽  
Venous Pressure ◽  
Atrial Pressure ◽  
Left Atrial Pressure ◽  
Central Venous ◽  
Pulmonary Arterial

Positive end-expiratory pressure (PEEP) increases central venous pressure, which in turn impedes return of systemic and pulmonary lymph, thereby favoring formation of pulmonary edema with increased microvascular pressure. In these experiments we examined the effect of thoracic duct drainage on pulmonary edema and hydrothorax associated with PEEP and increased left atrial pressure in unanesthetized sheep. The sheep were connected via a tracheostomy to a ventilator that supplied 20 Torr PEEP. By inflation of a previously inserted intracardiac balloon, left atrial pressure was increased to 35 mmHg for 3 h. Pulmonary arterial, systemic arterial, and central venous pressure as well as thoracic duct lymph flow rate were continuously monitored, and the findings were compared with those in sheep without thoracic duct cannulation (controls). At the end of the experiment we determined the severity of pulmonary edema and the volume of pleural effusion. With PEEP and left atrial balloon insufflation, central venous and pulmonary arterial pressure were increased approximately threefold (P less than 0.05). In sheep with a thoracic duct fistula, pulmonary edema was less (extra-vascular fluid-to-blood-free dry weight ratio 4.8 +/- 1.0 vs. 6.1 +/- 1.0; P less than 0.05), and the volume of pleural effusion was reduced (2.0 +/- 2.9 vs. 11.3 +/- 9.6 ml; P less than 0.05). Our data signify that, in the presence of increased pulmonary microvascular pressure and PEEP, thoracic duct drainage reduces pulmonary edema and hydrothorax.

Central venous pressure in humans during short periods of weightlessness

1987 ◽  
Vol 63 (6) ◽  
pp. 2433-2437 ◽  
Author(s):  
P. Norsk ◽  
N. Foldager ◽  
F. Bonde-Petersen ◽  
B. Elmann-Larsen ◽  
T. S. Johansen
Keyword(s):  
Heart Rate ◽  
Central Venous Pressure ◽  
Supine Position ◽  
Parabolic Flight ◽  
Venous Pressure ◽  
Central Venous Catheters ◽  
Sitting Position ◽  
Central Venous ◽  
Pressure Transducers ◽  
Gauge Pressure

Central venous pressure (CVP) was measured in 14 males during 23.3 +/- 0.6 s (mean +/- SE) of weightlessness (0.00 +/- 0.05 G) achieved in a Gulfstream-3 jet aircraft performing parabolic flight maneuvers and during either 60 or 120 s of +2 Gz (2.0 +/- 0.1 Gz). CVP was obtained using central venous catheters and strain-gauge pressure transducers. Heart rate (HR) was measured simultaneously in seven of the subjects. Measurements were compared with values obtained inflight at 1 G with the subjects in the supine (+1 Gx) and upright sitting (+1 Gz) positions, respectively. CVP was 2.6 +/- 1.5 mmHg during upright sitting and 5.0 +/- 0.7 mmHg in the supine position. During weightlessness, CVP increased significantly to 6.8 +/- 0.8 mmHg (P less than 0.005 compared with both upright sitting and supine inflight). During +2 Gz, CVP was 2.8 +/- 1.4 mmHg and only significantly lower than CVP during weightlessness (P less than 0.05). HR increased from 65 +/- 7 beats/min at supine and 70 +/- 5 beats/min during upright sitting to 79 +/- 7 beats/min (P less than 0.01 compared with supine) during weightlessness and to 80 +/- 6 beats/min (P less than 0.01 compared with upright sitting and P less than 0.001 compared with supine) during +2 Gz. We conclude that the immediate onset of weightlessness induces a significant increase in CVP, not only compared with the upright sitting position but also compared with the supine position at 1 G.

scholarly journals Uppermost Blood Levels of the Right and Left Atria in the Supine Position

2007 ◽  
Vol 107 (2) ◽  
pp. 260-263 ◽  
Author(s):  
Jeong-Hwa Seo ◽  
Chul-Woo Jung ◽  
Jae-Hyon Bahk
Keyword(s):  
Pulmonary Artery ◽  
Central Venous Pressure ◽  
Supine Position ◽  
Pressure Transducer ◽  
Venous Pressure ◽  
Blood Levels ◽  
Pulmonary Artery Wedge Pressure ◽  
Central Venous ◽  
Significant Difference ◽  
Wedge Pressure

Background To eliminate the influence of hydrostatic pressure, proper transducer positions for central venous pressure and pulmonary artery wedge pressure are at the uppermost blood levels of right atrium (RA) and left atrium (LA). This study was performed to investigate accurate reference levels of central venous pressure and pulmonary artery wedge pressure in the supine position. Methods Chest computed tomography images of 96 patients without history of cardiothoracic surgery, heart disease, or cardiothoracic anatomical abnormality were retrospectively reviewed. The anteroposterior (AP) diameter of the thorax and the vertical distances from the skin on the back to the most anterior portion of RA (RA height) and LA (LA height) were measured. Their ratios were abbreviated, respectively, as RA height/AP diameter and LA height/AP diameter. Data are expressed as mean +/- SD (range). Results There was a significant difference [4.6 +/- 1.0 (1.6-6.4) cm; P &lt; 0.001] between RA and LA heights. AP diameter was positively correlated with RA and LA heights (R = 0.839 and 0.700, respectively; P &lt; 0.001). There was also a significant difference between RA height/AP diameter [0.83 +/- 0.03 (0.71-0.91)] and LA height/AP diameter [0.62 +/- 0.04 (0.52-0.72)] (P &lt; 0.001). Conclusion In the supine position, a central venous pressure transducer should be positioned approximately 4.6 cm higher than a pulmonary artery wedge pressure transducer. The external reference level for central venous pressure seems to be at approximately four fifths of the AP diameter of the thorax from the back, and that for pulmonary artery wedge pressure seems to be at approximately three fifths of the AP diameter.

Elevation of superior vena caval pressure increases extravascular lung water after endotoxemia

1987 ◽  
Vol 62 (3) ◽  
pp. 1006-1009 ◽  
Author(s):  
S. J. Allen ◽  
R. E. Drake ◽  
J. Katz ◽  
J. C. Gabel ◽  
G. A. Laine
Keyword(s):  
Pulmonary Hypertension ◽  
Central Venous Pressure ◽  
Pulmonary Edema ◽  
Left Atrial ◽  
Superior Vena ◽  
Venous Pressure ◽  
Weight Ratio ◽  
Central Venous ◽  
Superior Vena Caval ◽  
Extravascular Fluid

In many sheep Escherichia coli endotoxin results in pulmonary hypertension, increased microvascular permeability, pulmonary edema, and increased central venous pressure. Since lung lymph drains into the systemic veins, increases in venous pressure may impair lymph flow sufficiently to enhance the accumulation of extravascular fluid. We tested the hypothesis that, following endotoxin, elevating the venous pressure would increase extravascular fluid. Thirteen sheep were chronically instrumented with catheters to monitor left atrial pressure (LAP), pulmonary arterial pressure (PAP), and superior vena caval pressure (SVCP) as well as balloons to elevate LAP and SVCP. These sheep received 4 micrograms/kg endotoxin, and following the pulmonary hypertensive spike the left atrial balloon was inflated so that (PAP + LAP)/2 = colloid osmotic pressure. It was necessary to control PAP + LAP in this way to minimize the sheep-to-sheep differences in the pulmonary hypertension. We elevated the SVCP to 10 or 17 mmHg or allowed it to stay low (3.2 mmHg). After a 3-h period, we killed the sheep and removed the right lungs for determination of the extravascular fluid-to-blood-free dry weight ratio (EVF). Sheep with SVCP elevated to 10 or 17 mmHg had significant increases in EVF (5.2 +/- 0.1 and 5.6 +/- 1.2) compared with the sheep in which we did not elevate SVCP (EVF = 4.5 +/- 0.4). These results indicate that sustained elevation in central venous pressure in patients contributes to the amount of pulmonary edema associated with endotoxemia.

Central venous pressure in humans during microgravity

1996 ◽  
Vol 81 (1) ◽  
pp. 408-412 ◽  
Author(s):  
N. Foldager ◽  
T. A. Andersen ◽  
F. B. Jessen ◽  
P. Ellegaard ◽  
C. Stadeager ◽  
...  
Keyword(s):  
Central Venous Pressure ◽  
Supine Position ◽  
Pressure Transducer ◽  
Space Shuttle ◽  
Parabolic Flight ◽  
Venous Pressure ◽  
Simulation Studies ◽  
Central Venous ◽  
Healthy Humans ◽  
Intravascular Pressure

Based on the results of head-down simulation studies and the results of parabolic flights, the hypothesis was tested that central venous pressure (CVP) in humans increases during microgravity (weightlessness) compared with during the ground-based supine position. CVP was recorded with an intravascular pressure transducer in seven healthy humans during short (20-s) periods of microgravity created by parabolic-flight maneuvers and in one astronaut before, during, and up to 3 h after launch of the Spacelab D-2 mission (Space Transport System-55). When the subjects were supine during the parabolic maneuver, CVP decreased during microgravity from 6.5 +/- 1.3 to 5.0 +/- 1.4 mmHg (P < 0.05). during the Spacelab D-2 mission, CVP was 6.2 mmHg during the initial minutes of microgravity, which was very similar to the value of 6.5 mmHg in the supine position 3.5 h before launch of the space shuttle. During the subsequent 3 h of weightlessness, CVP during rest varied between 2.0 and 6.2 mmHg. We conclude that CVP during short (20-s) and longer (3-h) periods of microgravity is close to or below that of the supine position on the ground.

scholarly journals Venous Return and Cardiac Filling in Varanid Lizards

1984 ◽  
Vol 113 (1) ◽  
pp. 389-399 ◽  
Author(s):  
KJELL JOHANSEN ◽  
WARREN W. BURGGREN
Keyword(s):  
Central Venous Pressure ◽  
Cardiac Cycle ◽  
Venous Pressure ◽  
Cycle Duration ◽  
Central Venous ◽  
Venous Flow ◽  
Atrial Contraction ◽  
Short Period ◽  
Filling Agent ◽  
Cardiac Filling

1. The duration of ventricular diastole relative to the cardiac cycle length is much shorter (46%) in varanids than in mammals (&gt;70%). 2. Atrial systolic pressures were high (15–20 cmH2O), and atrial contraction was apparent in pressure waveforms from the ventricular cavum arteriosum and cavum pulmonale. Atrial contraction coincides with the short period of ventricular diastole and represents the filling agent for the ventricular cava. 3. Increased central venous flow coincides with ventricular contraction, which by reducing the intrapericardial pressure will promote the expansion and filling of the atria and central veins, implying a suctional element of cardiac filling. 4. Inspiration during spontaneous breathing will reduce central venous pressure, steepen the pressure gradient towards the heart and aid flow towards central veins. There is a positive correlation between the systolic level of central venous pressure and cardiac cycle duration.

Central venous pressure in space

1996 ◽  
Vol 81 (1) ◽  
pp. 19-25 ◽  
Author(s):  
J. C. Buckey ◽  
F. A. Gaffney ◽  
L. D. Lane ◽  
B. D. Levine ◽  
D. E. Watenpaugh ◽  
...  
Keyword(s):  
Central Venous Pressure ◽  
Space Shuttle ◽  
Venous Pressure ◽  
Life Sciences ◽  
Left Ventricular ◽  
Filling Pressure ◽  
Fluid Distribution ◽  
Central Venous ◽  
Cardiac Filling Pressure ◽  
Cardiac Filling

Gravity affects cardiac filling pressure and intravascular fluid distribution significantly. A major central fluid shift occurs when all hydrostatic gradients are abolished on entry into microgravity (microG). Understanding the dynamics of this shift requires continuous monitoring of cardiac filling pressure; central venous pressure (CVP) measurement is the only feasible means of accomplishing this. We directly measured CVP in three subjects: one aboard the Spacelab Life Sciences-1 space shuttle flight and two aboard the Spacelab Life Sciences-2 space shuttle flight. Continuous CVP measurements, with a 4-Fr catheter, began 4 h before launch and continued into microG. Mean CVP was 8.4 cmH2O seated before flight, 15.0 cmH2O in the supine legs-elevated posture in the shuttle, and 2.5 cmH2O after 10 min in microG. Although CVP decreased, the left ventricular end-diastolic dimension measured by echocardiography increased from a mean of 4.60 cm supine preflight to 4.97 cm within 48 h in microG. These data are consistent with increased cardiac filling early in microG despite a fall in CVP, suggesting that the relationship between CVP and actual transmural left ventricular filling pressure is altered in microG.

Mechanism for changes in vasopressin during acute exposure at 3 atm abs air

1997 ◽  
Vol 273 (1) ◽  
pp. R259-R264 ◽  
Author(s):  
R. Torii ◽  
S. Sagawa ◽  
F. Wada ◽  
K. Nagaya ◽  
Y. Endo ◽  
...  
Keyword(s):  
Central Venous Pressure ◽  
Human Subjects ◽  
Venous Pressure ◽  
Venous Blood ◽  
Plasma Osmolality ◽  
Blood Gases ◽  
Esophageal Pressure ◽  
Internal Source ◽  
Central Venous ◽  
Cardiac Volume

Plasma arginine vasopressin (AVP) concentration is reduced in human subjects during prolonged saturation dive exposures of 4 atmospheres absolute (atm abs) and greater. The objectives of the present study were to determine if AVP would be reduced in eight male subjects during a 1-h exposure of 3 atm abs air and, if so, to determine the mechanisms responsible for the AVP response. Assessments of transmural central venous pressure (central venous pressure-esophageal pressure) and cardiac volume measurements were made to evaluate the possible role of cardiopulmonary receptors on the AVP response. Also, plasma osmolality (P(osmol)), venous blood gases, and mean corpuscular volume (MCV) were determined to evaluate potential effects of osmoreceptor and other fluid shifts on AVP release. AVP decreased (P < 0.05) by 0.5 microU/ml at 3 atm abs, whereas the transmural central venous pressure and cardiac volume remained unchanged throughout the experimental periods. A significant reduction (P < 0.05) in P(osmol) (by approximately 3 mosmol/kgH2O) was detected at 3 atm abs. Therefore, we conclude that the reduction in P(osmol) may cause the reduction in AVP during exposure to 3 atm abs pressure. The reduction in P(osmol) without water intake requires the postulation of an internal source of water. We propose that the threefold increase (P < 0.01) in venous PO2 and concomitant decrease (P < 0.05) in venous MCV suggest that the red blood cell may contribute to hypotonicity at 3 atm abs.

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