Pneumatic anti-shock garment: State of the art 1988
SummaryThe responses of hypovolemic patients would be expected to be similar to experimental animals that were hypovolemic. Normovolemic patients would be expected to respond as do the normovolemic experimental animals. Hypovolemic patients do not necessarily respond the same as do normovolemic patients or volunteers.The amount of external pressure applied by the device is directly proportional to the amount of tissue pressure increase. Tissue pressure is transmitted to the vessel as reduction transmural pressure, or in change in the size of the vessels and subsequent increase in SVR. Patient response to external pressure varies with the amount of device pressure. The optimal pressure of the PASG is in the range of 60 to 80 torr. Although exceeding this value does not appear to be necessary, it is not harmful in the short term (less than 90 minutes). Using less pressure reduces the SVR and, therefore, the blood pressure response. Keeping the external pressure at approximately 40 torr appears to be ideal for hemorrhage control.Of the more than 300 articles that have appeared in the recent literature addressing the PASG, at least 190 have discussed specific scientific experiments in the animal laboratory, in the human laboratory, or in the clinical environment, in which results gathered addressed how, why, or if the PASG worked. These studies demonstrate that the PASG does, in fact, improve blood pressure, control hemorrhage, improve carotid and upper body blood flow, improve the ability of the prehospital provider to start IV lines, and improve survival (particularly short-term) with few hospital and even fewer prehospital complications. The device produces its blood pressure response by improving preload, increasing SVR, and mobilizing some blood (500 to 1,000 mL) to the upper body compartment above the device. These responses are most probably produced by decreasing the radius of the vessels compressed by the device, decreasing the compartment volume, and differentially affecting the blood flow without and within the device.Hemorrhage is controlled by increasing the external pressure on the vessel by the transmitted increased tissue pressure, reducing the vascular lumen, and reducing the area of the laceration.Short-term survival is improved by decreasing intra-abdominal hemorrhage and improving perfusion (maintaining better oxygenation in the heart-brain-lung circulation.)Long-term survival is improved because the device controls hemorrhage, maintains blood pressure, and aloows delivery of the severely injured patient to the trauma center and within the hospital while awaiting an OR, as in the case of a leaking aortic aneurysm. In EMS systems with short response times to situations of penetrating trauma and ability to move the patient quickly to definitive care, the improvement of long-term survival may be minimal.Cerebral perfusion and perfusion of the heart and lungs are definitely enhanced by use of the device. This is identified by both improved carotid blood flow and improved carotid size. Cardiac arrest survival with VF and PIVR is somewhat improved with PASG use. Pediatric usages are the same as adults.Studies to date demonstrate improvement in our accepted resuscitation components (blood pressure, carotid blood flow, and hemorrhage control) and allow the patient to be delivered to the trauma center in a more survivable condition than without their use. The major complications remain rapid deflation without reestablishing intravascular volume.One question remains to be asked. If the Mattox209 study of no improvement in survival holds true under further investigation and if all of the many other studies are also true that the PASG improves blood pressure, improves cerebral and cardiac and pulmonary blood flow, how can both be true? These physiological conditions we always considered important in assessing a patient's resuscitation; have we been resuscitating patients using the wrong measures? PASG does all of the things we think are “good.” If PASG is not good, then our definitions of good may, in fact, not be correct.The prehospital complication rate is far less than one per 100,000 uses. Most of the complications have occurred inside the hospital while the device was under direct physician supervision. Even so, the complication rate is less than one per 10,000 uses. This complication rate seems to decrease with experience with the device. The device, like any other, cannot be used indiscriminately or without caution and observation. It can produce major problems.No study demonstrates a worse survival rate using the device on abdominal and lower extremity trauma and many demonstrate an improved survival rate in these patients either directly or indirectly. Thoracic injuries may be different. Blood pressure is improved by three mechanisms: increased SVR, decreased vascular volume, and, to a limited extent, translocation of blood. The amount of external pressure by the device is directly proportional to the responses in these physiologic functions. Optimal pressure for patient care is between 60 and 80 torr. Decreased blood flow occurs beneath the device and improved blood flow in those organs not compressed by the device. Hemorrhage from organs compressed by the device is reduced. Complications are directly proportional to the length of time the device is elevated at higher pressures and the level of hypotension and, therefore, hypoperfusion of the compressed tissues. Pediatric uses are the same as adults.
لباس ضد شوک پنوماتیک: آخرین هنر در سال ۱۹۸۸
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