A study performed on 33 blood donors shows that pulse flow drops significantly and substantially after loss of one unit of blood when there has been no change in blood pressure. This suggests that the Pulse Flowmeter may be useful in early detection of blood loss during surgery and in the peri-operative period. (There is no data yet on patients undergoing hemodynamically significant blood loss in surgery).

DETECTION AND TREATMENT OF BLOOD LOSS: The Pulse Flowmeter is sensitive to changes in peripheral vascular flow secondary to blood loss  before other vital signs, such as blood pressure or pulse oximetry change.  Thus, pulse flow measurements may be very useful when blood loss is occult or quantification of visible blood loss is difficult or impossible.

Surgery- During and after surgery, there is often occult blood loss. Patients may be monitored with the Pulse Flowmeter to determine if there are significant decreases in flow which may indicate such occult hemorrhage both intra and postoperatively. A drop in pulse flow relative to flow measurements made prior to starting surgery might be an indication that hypovolemia secondary to hemorrhage may have taken place. 

Trauma – When trauma patients are first seen by medical personnel, they may have already suffered significant blood loss.  Pulse Flow measurements may be taken and, based upon normal tables, an initial evaluation may be made to determine if such blood loss has occurred.  After initial measurements are made, serial pulse flow measurements may be useful to alert the medical team to further blood loss.

Femoral Artery Rupture - A rare but extremely serious complication of intra-aortic balloon pumping is rupture of the femoral artery upon removal of a damaged, blood-filled balloon.  This can result in occult retroperitoneal blood loss which will cause a decrease in pulse flow.  Such an occurrence may be determined by the Pulse Flowmeter.

Battlefield Injuries – Soldiers having sustained serious internal injuries accompanied by bleeding will have markedly reduced pulse flow well before the onset of shock.  The U.S. Army’s Combat Causality Care Center has indicated that a miniaturized and simplified version of the Pulse Flowmeter would be of value to them for assessment of such battlefield injuries.   

Blood Transfusion - In addition to detecting blood loss, the Pulse Flowmeter may be used to evaluate the effectiveness of blood transfusion.  A not uncommon problem that occurs when treating trauma patients is overly aggressive transfusion resulting in "shock lung."  Because blood volume and pulse flow are interrelated, the Pulse Flowmeter may provide a sensitive indicator of a safe transfusion end point.

Apart from the blood loss study, there are a number of ongoing human clinical trials with sufficient statistical power to determine the role that the Pulse Flowmeter may play in managing other medical conditions.  Such trials  include monitoring Pulse Flow  in women undergoing cesarean section, heart transplant candidates receiving an inotropic challenge and patients undergoing renal hemodyalysis.

Because the Pulse Flowmeter provides information about  peripheral blood flow, it suggests that the measurement may be also useful for the management of shock and other medical conditions including vascular instability of the infant in the neonatal ICU, intra-aortic blood pump use, congestive heart failure, use of vasoactive medications, syncope, dehydration, deep vein thrombosis, thermal injuries, renal dialysis, assessing the integrity of the palmar arch before performing radial artery harvesting or radial artery cardiac catheterization, surrogate for cardiac output monitoring and hypertension.

Click to see a discussion of possible use of pulse flowmetry in shock.

Click to see a discussion of possible uses in other medical conditions.

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