Background: Decompression to simulated altitude causes super-saturation of nitrogen desolved in body tissues and can result in venous gas emboli (VGE), which are usually "cleared" in the lung. Large intravenous boli of air administered to animals increase pulmonary artery pressure (PAP), and may induce cross-over of gas to the left side of the heart (creating dangerous arterial gas emboli). This study was conducted to determine whether high VGE grades induced at simulated altitude elevate PAP in humans.
Methods: Eight human subjects with subclinical tricuspid regurgitation were exposed to simulated altitude of > or = 24,000 ft (7315 m) for up to 4 h. Systolic PAP was derived from Doppler ultrasound echo imaging measurements of peak flow velocity of the regurgitant jet. VGE was rated using the Spencer scale. A technique of "bubble titration" was employed with changes in exercise and altitude to maintain sufficient bubbles without decompression sickness.
Results: All subjects developed grade III-IV VGE, but 3 developed decompression sickness, resulting in earlier termination. Pre-exposure systolic PAP averaged 24.4 +/- 1.3 (SE) mm Hg. After 1, 2, 3 and 4 h, systolic PAP was 23.7 +/- 1.2 (n = 8), 23.4 +/- 1.1 (n = 8), 23.3 +/- 1.0 (n = 6), and 25.9 +/- 0.6 (n = 5) mm Hg, respectively. Systolic PAP remained unchanged, in spite of bubble grades III-IV for up to 4 h.
Conclusion: As systolic PAP did not increase with hypobaric exposures that created substantial VGE, the bubble loading was not sufficient to overwhelm the lung clearing capacity. The risk of high PAP resulting in VGE cross-over is low during typical operational altitude exposures.
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Asian J Neurosurg
December 2024
Division of Neuroanesthesia and Neurocritical Care, Department of Anaesthesiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India.
An acute increase in intracranial pressure (ICP) has been shown to affect cardiac function due to brain ischemia and the associated increased sympathetic activity. However, there is limited literature on the changes in cardiac function in clinical scenarios where there is a gradual and progressive increase in ICP, such as in brain tumors. We aimed to assess and compare the cardiac function in patients with primary supratentorial brain tumors presenting with and without raised ICP for neurosurgery.
View Article and Find Full Text PDFJ Cardiothorac Vasc Anesth
November 2024
Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, CA; Lucile Packard Children's Hospital, Stanford University Medical Center, Palo Alto, CA. Electronic address:
Lupus
January 2025
Rheumatology Division, Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, Brazil.
Objective: To evaluate the possible reversibility of PAH to a normopressoric state in SLE after induction immunosuppressive (IS) and predictors of response.
Methods: We retrospectively evaluated all SLE-PAH patients who underwent IS therapy at our center. PAH reversion was defined as the normalization of pulmonary arterial pressure (PAP), either by the presence of systolic PAP <40 mmHg on echocardiogram or mean PAP <20 mmHg on right heart catheterization (RHC).
Clin Res Cardiol
November 2024
Department of Medicine I, Cardiology and Angiology, University Hospital Giessen and Marburg, Justus Liebig University, Klinikstr. 33, 35392, Giessen, Germany.
Introduction: Supervised physical exercise has been shown to benefit patients with heart failure with preserved/mildly reduced ejection fraction (HFpEF/HfmrEF) by improving symptoms and diastolic function. This study aimed to investigate the correlation between unsupervised daily physical activity and changes in daily pulmonary artery pressure (PAP) in patients with stable NYHA class III heart failure (HF) and left ventricular ejection fraction (LVEF) of 45% or higher.
Methods: Daily physical activity was monitored over a 3-month period using a Holter-ECG with an accelerometer that calculated an activity-associated, heart rate-derived metabolic equivalent of task (MET) score.
Eur Respir J
December 2024
Bethanien Hospital, Institute for Pneumology at the University of Cologne, Solingen, Germany
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