Pulmonary artery pressure measurement in patients with elevated pressures: effect of backrest elevation and method of measurement

1992 ◽  
Vol 1 (2) ◽  
pp. 61-69 ◽  
Author(s):  
K Dobbin ◽  
S Wallace ◽  
J Ahlberg ◽  
M Chulay
Keyword(s):  
Mechanical Ventilation ◽  
Mean Arterial Pressure ◽  
Pulmonary Artery ◽  
Pulmonary Artery Pressure ◽  
Mixed Venous Oxygen Saturation ◽  
Graphic Recording ◽  
Artery Pressure ◽  
Normal Breathing ◽  
Venous Oxygen Saturation ◽  
Mixed Venous

OBJECTIVE: To determine whether pulmonary artery pressure measurement is accurate if the head of the bed is elevated; to compare the end-expiratory graphic recording and digital monitor methods for pulmonary artery pressure measurement; to determine whether either mean arterial pressure or mixed venous oxygen saturation changes during backrest elevation. DESIGN: Nonrandomized clinical trial. SETTING: A six-bed cardiac surgical intensive care unit of a 540-bed federal facility. POPULATION: Twenty-five postoperative cardiac surgical patients with elevated pulmonary artery pressures (systolic higher than 35 mm Hg). INTERVENTIONS: In supine patients pulmonary artery pressures were measured at each of the following backrest elevations: 0, 20, 30, 45 and again at 0 degrees. Measurements were obtained once during mechanical ventilation and once during normal breathing after extubation. MAIN OUTCOME MEASURES: End-expiratory graphic recording of pulmonary artery pressures; digital monitor values of pulmonary artery pressures; mean arterial pressure; and mixed venous oxygen saturation. RESULTS: No statistical difference was found in pulmonary artery pressures measured at each of the backrest elevations during mechanical ventilation or normal breathing after extubation. Pulmonary artery diastolic and pulmonary capillary wedge pressures obtained with the digital monitor method were significantly lower than the end expiratory graphic recording method during normal breathing after extubation but not during mechanical ventilation. No changes in mean arterial pressure or mixed venous oxygen saturation occurred during backrest elevation. CONCLUSIONS: These results show that pulmonary artery pressures can be measured accurately with the head of the bed in an elevated position. The data indicate that obtaining pulmonary artery pressure measurements from the digital display of the bedside monitor is accurate when respiratory wave form fluctuations are minimal but may lead to inaccurate values with prominent respiratory fluctuations. Further research is needed to validate this finding in different patient populations and with other models of monitoring equipment.

Comparison of methods of measuring pulmonary artery pressure

1997 ◽  
Vol 6 (4) ◽  
pp. 324-332 ◽  
Author(s):  
JL Lundstedt
Keyword(s):  
Mechanical Ventilation ◽  
Cardiac Surgery ◽  
Pulmonary Artery ◽  
Pulmonary Artery Pressure ◽  
Spontaneous Breathing ◽  
Systolic Pressure ◽  
Graphic Method ◽  
Difference Scores ◽  
Artery Pressure ◽  
The Difference

BACKGROUND: Pulmonary artery waveforms fluctuate because of changes in intrathoracic pressure caused by respirations. Monitoring system algorithms determine digital displays of pressure measurements on the basis of recognition, analysis, and comparison of consecutive waveforms. OBJECTIVE: To compare three methods of measuring pulmonary artery pressure during mechanical ventilation and spontaneous breathing in cardiac surgery patients with stable hemodynamics. METHODS: Pulmonary artery pressure was measured during mechanical ventilation after cardiac surgery in 53 patients; 37 of the patients were studied again after extubation. Three monitoring methods were compared: graphic strip recording, the "stop cursor" (monitor screen freezing) method, and digital-display recording. Difference scores were calculated between the methods and analyzed for frequency and direction. RESULTS: All comparisons showed differences of at least +/-3 mm Hg in measurements obtained with the three methods. During mechanical ventilation, the digital and graphic measurements of systolic pressure varied most often; 57% (30/53) of the comparisons had difference scores of at least +/-3 mm Hg. The cursor and graphic measurements of diastolic pressures varied least often; 6% (3/53) of the comparisons had difference scores of at least +/-3 mm Hg. As expected, the digital method most often gave higher results than the graphic method. During spontaneous breathing, measurements of systolic pressure varied more often (38% to 53%) than did measurements of diastolic pressure (12% to 37%). Unexpectedly, for systolic pressures, the difference between digital and graphic measurements was 3 mm Hg or more 30% (11/37) of the time, and the difference between cursor and graphic measurements was 3 mm Hg or more 53% (17/32) of the time. CONCLUSIONS: Because of physiological and technical influences, measurements of systolic and diastolic pressures in the pulmonary artery made with the digital and cursor methods were not as reliable as measurements made with the graphic method. The findings support continued use of the graphic method for accurate measurements of pulmonary artery pressure.

Retinal venous oxygen saturation and cardiac output during controlled hemorrhage and resuscitation

2003 ◽  
Vol 94 (3) ◽  
pp. 891-896 ◽  
Author(s):  
Kurt R. Denninghoff ◽  
Matthew H. Smith ◽  
Art Lompado ◽  
Lloyd W. Hillman
Keyword(s):  
Cardiac Output ◽  
Pulmonary Artery ◽  
Oxygen Saturation ◽  
Femoral Artery ◽  
Mixed Venous Oxygen Saturation ◽  
Oxygen Level ◽  
Shed Blood ◽  
Venous Oxygen Saturation ◽  
Retinal Artery ◽  
Mixed Venous

The objective was to test calibration of an eye oximeter (EOX) in a vitiligo swine eye and correlate retinal venous oxygen saturation (SrvO2), mixed venous oxygen saturation (SvO2), and cardiac output (CO) during robust changes in blood volume. Ten anesthetized adult Sinclair swine with retinal vitiligo were placed on stepwise decreasing amounts of oxygen. At each oxygen level, femoral artery oxygen saturation (SaO2) and retinal artery oxygen saturation (SraO2) were obtained. After equilibration on 100% O2, subjects were bled at 1.4 ml · kg−1· min−1for 20 min. Subsequently, anticoagulated shed blood was reinfused at the same rate. During graded hypoxia, exsanguination, and reinfusion, SraO2and SrvO2were measured by using the EOX, and CO and SvO2were measured by using a pulmonary artery catheter. During graded hypoxia, SraO2correlated with SaO2( r = 0.92). SrvO2correlated with SvO2( r = 0.89) during exsanguination and reinfusion. SvO2and SrvO2correlated with CO during blood removal and resuscitation ( r = 0.92). Use of vitiligo retinas improved the calibration of EOX measurements. In this robust hemorrhage model, SrvO2correlates with CO and SvO2across the range of exsanguination and resuscitation.

scholarly journals Long term effects of non-invasive mechanical ventilation on pulmonary haemodynamics in patients with chronic respiratory failure

Thorax ◽  
2001 ◽  
Vol 56 (7) ◽  
pp. 524-528
Author(s):  
B Schönhofer ◽  
T Barchfeld ◽  
M Wenzel ◽  
D Köhler
Keyword(s):  
Mechanical Ventilation ◽  
Respiratory Failure ◽  
Gas Exchange ◽  
Pulmonary Artery ◽  
Pulmonary Artery Pressure ◽  
Chronic Respiratory Failure ◽  
Artery Pressure ◽  
Mean Pulmonary Artery Pressure ◽  
Pulmonary Haemodynamics

BACKGROUNDIt is not known whether long term nocturnal mechanical ventilation (NMV) reduces pulmonary hypertension in patients with chronic respiratory failure (CRF).METHODSPulmonary haemodynamics, spirometric values, and gas exchange were studied in 33 patients requiring NMV due to CRF (20 with thoracic restriction, 13 with chronic obstructive pulmonary disease (COPD)) at baseline and after 1 year of NMV given in the volume cycled mode. Patients with COPD also received supplemental oxygen.RESULTSLong term NMV improved gas exchange while lung function remained unchanged. Mean pulmonary artery pressure at rest before NMV was higher in patients with thoracic restriction than in those with COPD (33 (10) mm Hgv 25 (6) mm Hg). After 1 year of NMV mean pulmonary artery pressure decreased in patients with thoracic restriction to 25 (6) mm Hg (mean change –8.5 mm Hg (95% CI –12.6 to –4.3), p<0.01) but did not change significantly in patients with COPD (mean change 2.2 mm Hg (95% CI –0.3 to 4.8)).CONCLUSIONSLong term NMV in CRF improves pulmonary haemodynamics in patients with thoracic restriction but not in patients with COPD.

Effect of Body Repositioning after Venous Air Embolism

1997 ◽  
Vol 86 (3) ◽  
pp. 710-717 ◽  
Author(s):  
Hans J. Geissler ◽  
Steven J. Allen ◽  
Uwe Mehlhorn ◽  
Karen L. Davis ◽  
William P. Morris ◽  
...  
Keyword(s):  
Mean Arterial Pressure ◽  
Pulmonary Artery ◽  
Right Ventricular ◽  
Pulmonary Artery Pressure ◽  
Supine Position ◽  
Air Embolism ◽  
Outflow Obstruction ◽  
Venous Air Embolism ◽  
Artery Pressure ◽  
Cardiac Dimension

Background Current therapy for massive venous air embolism (VAE) may include the use of the left lateral recumbent (LLR) position, although its effectiveness has been questioned. This study used transesophageal echocardiography to evaluate the effect of body repositioning on intracardiac air and acute cardiac dimension changes. Methods Eighteen anesthetized dogs in the supine position received a venous air injection of 2.5 ml/kg at a rate of 5 ml/ s. After 1 min the dogs were repositioned into either the LLR, LLR 10 degrees head down (LLR-10 degrees), right lateral recumbence, or remained in the supine position. Results Repositioning after VAE resulted in relocation of intracardiac air to nondependent areas of the right heart. Peak right ventricular (RV) diameter increase and mean arterial pressure decrease were greater in the repositioned animals compared with those in the supine position (P &lt; 0.05). Right ventricular diameter and mean arterial pressure showed an inverse correlation (r = 0.81). Peak left atrial diameter decrease was greater in the LLR and LLR-10 degrees positions compared with the supine position (P &lt; 0.05). Repositioning did not influence peak pulmonary artery pressure increase, and no correlation was found between RV diameter and pulmonary artery pressure. All animals showed electrocardiogram and echocardiographic changes reconcilable with myocardial ischemia. Conclusions In dogs, body repositioning after VAE provided no benefit in hemodynamic performance or cardiac dimension changes, although relocation of intracardiac air was demonstrated. Right ventricular air did not appear to result in significant RV outflow obstruction, as pulmonary artery pressure increased uniformly in all groups and was not influenced by the relocation of intracardiac air. The combination of increased RV afterload and arterial hypotension, possibly with subsequent RV ischemia rather than RV outflow obstruction by an airlock appeared to be the primary mechanism for cardiac dysfunction after VAE.

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