Automated Assessment of Pulmonary Mechanics and Fluid Responsiveness
Abstract
Acute lung injury (ALI) and hypovolemia due to hemorrhage, burns and other injuries are not uncommon in critical care. Hypovolemia is primarily treated with intravenous fluid. ALI is treated by increasing oxygen, positive end expiratory pressure (PEEP) and positive pressure ventilation. Unfortunately, PEEP reduces blood flow to the heart, which can result in excessive fluid needs and edema. Optimization of therapeutic endpoints for hypovolemia in ALI has been the subject of several investigations. We hypothesized that a novel ventilation maneuver, called a pressure volume loop (PVloop - also termed PVcurve) would optimize PEEP and identify how much fluid is needed. Anesthetized swine underwent hemorrhage and resuscitation with and without ALI. Catheters were placed for blood sampling, pressure monitoring, mean arterial pressure (MAP), cardiac output (CO) and fluid infusions. Specific variables collected included central venous pressure (CVP), pulmonary artery occlusive pressure (PAOP), heart rate (HR), pulse pressure CO and MAP every 10 min. ALI was induced to achieve a partial pressure of arterial oxygen (PaO2) to fractional inspired oxygen (FiO2) or PaO2/FiO2<150. Hypovolemia was induced by a rapid hemorrhage followed by fluid resuscitation to achieve PAOP of 5, 10, 15 and 20 mmHg. Pilot studies showed that a PV loop could best be achieved using inspiratory pressure 20 cm H2O above PEEP. Data demonstrated that PVloop could be used to assess iv fluid needs after ALI + single hemorrhage. We then compared swine undergoing a rapid hemorrhage followed by slower hemorrhage and fluid resuscitation as a model of en route care. Two fluid resuscitation strategies were compared. The test group used a PVloop and pulse pressure to determine fluid needs. The control group used pulse pressure variability to administer fluid. No differences in resuscitation endpoints or oxygenation were observed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2022
- Accession Number
- AD1191462
Entities
People
- Chris Blakeman
- Dario Rodriguez
- Michael Kinsky
- Richard D Branson
Organizations
- University of Cincinnati