Other Possible Medical Applications

Newborn ICU

Very low birth weight infants are at risk for infection and cardiovascular collapse. The Pulse Flowmeter device might be used to monitor these high-risk infants. Miniaturized electrodes have been developed and successfully tested.

Very low birth weight infants are at risk for neonatal sepsis (infection) which can lead to cardiovascular instability and death. It is anticipated that large changes in pulse flow, initially increasing and later decreasing will occur when a baby becomes septic.

A patent ductus arteriosus (PDA) is a common abnormality in newborn infants caused by the persistence of a vessel (the ductus arteriosus) which normally closes shortly after birth. A PDA is accompanied by increased pulse flow, which decreases when the ductus arteriosus closes. The Pulse Flowmeter might be a sensitive indicator of the condition and the effectiveness of medication used to treat the condition.

Intra-Aortic Balloon Pumping

Intra-aortic balloon pumping (IABP) is a commonly used procedure to provide cardiac support by means of a large balloon catheter placed in the femoral arteries. To operate effectively, the balloon must be properly positioned and timed to inflate and deflate in time with the cardiac cycle (counter-pulsation). Click to see data from an IABP patient.

The large catheters that are used for intra-aortic balloon pumping are associated with an approximately 3% incidence of severe limb ischemia. There is currently no satisfactory method for alerting the medical staff of such impending limb ischemia. The Pulse Flowmeter might be used in the management of this problem.

The precise timing of IABP inflation/deflation is critical to maximizing cardiac output, something that is currently somewhat of an “art.” Because cardiac output is closely related to peripheral vascular flow, the Pulse Flowmeter provides a quantitative indicator useful to adjusting IABP timing settings.

There are currently no satisfactory quanti­tative methods for evaluating peripheral vascular disease. The devices presently used in management of this problem provide only non-quantitative pulse volume recordings (PVR). The Pulse Flowmeter provides both waveforms indicating peripheral vascular flow as well as quantitative measurement of flow. Vascular specialists having seen the device and recognizing the value of direct quantitative measurement, have expressed interest in it.

Congestive Heart Failure

Because congestive heart failure is associated with increased peripheral vascular resistance and decreased peripheral vascular flow, the Pulse Flowmeter might be used in its detection and treatment. Ideally, baseline measurements of pulse flow might be made when patients are in good medical control and later used to determine the onset of symptoms and the effectiveness of treatment. Click to see data from CHF patients.

Research Evaluation of Vasoactive Medications

Currently, there are no satisfactory quantitative, non-invasive methods for assessing peripheral blood flow in humans to determine the effectiveness of vasoactive medications. The physiologic parameters of interest can only be measured with catheters placed in the heart and blood vessels. This makes the clinical evaluation of these drugs difficult. The Pulse Flowmeter might be used for such assessments.

Evaluation and Treatment of Syncope

Currently, patients with syncope (fainting spells) are evaluated with tilt testing (i.e. bringing a patient from a horizontal to a vertical position). Such testing is extremely discomforting to the patient and can produce cardiac arrhythmias. Because a decrease in pulse flow may occur well before a patient becomes symptomatic and faints, it might be possible to use the Pulse Flowmeter in conjunction with a briefer, modified form of tilt test that would also save physician time.

Detection and Treatment of Dehydration

It is well understood that dehydration produces a decrease in peripheral vascular flow and an increase in peripheral vascular resistance. Currently, the degree of dehydration is crudely estimated by clinical criteria such as skin turgor, with intravenous fluids being administered based upon a formula. Because the end point of dehydration is largely subjective, this may result in patients spending too much or too little time receiving IV fluids. The Pulse Flowmeter might be used as a sensitive, objective and unambiguous indicator of proper hydration.


Pre-eclampsia is a condition in which hypertension is accompanied by acute and significant changes in fluid content in the tissues.  Prresently, pre-eclampsia  must be identified by highly subjectively means by a clinician.  The Pulse Flowmeter may be used as a sensitive, objective and unambiguous indicator of fluid and electrolyte changes useful for identifying and treating pre-eclampsia.

Deep Vein Thrombosis

Deep vein thrombosis often is accompanied by compromised venous return resulting in limb swelling. This swelling may be easily and quantitatively measured with the baseline impedance measurement generated by the Pulse Flowmeter. In addition, in the case where one limb has a much lower pulse flow than the other limb, deep vein thrombosis may be revealed by the Pulse Flowmeter.

Thermal Injuries

Burns and frostbite are associated with decreased peripheral vascular flow to the affected area. The Pulse Flowmeter might be used to evaluate the degree of thermal injury and serial measurements might be used to estimate the return of function with treatment. It may also have a role in the assessment of tissue viability.

Renal Dialysis

As it is well recognized that dialysis patients frequently experience vascular instability due to large fluid and electrolyte shifts, it is important to have a simple and quantitative method to determine when a dialysis patient has reached their dry weight. Currently, that weight is estimated based on the history of prior dialysis sessions. As the patient loses fluid, the limb tissue impedance increases and can be monitored by the Pulse Flowmeter. When the limb impedance stops increasing, the patient should be close to their dry weight. Furthermore, when a patient loses too much fluid, their blood pressure and peripheral blood flow drop. This often results in serious hemodynamic instability. The Pulse Flowmeter should shows changes in flow well before a drop in blood pressure, giving medical personnel an early warning that hypotension may ensue. Click to see data from renal dialysis patients.

Quantitative Allen Test for Radial Artery Harvesting and/or Radial Artery Cardiac Catheterization

Radial arteries are now being used for coronary bypass grafts and to perform cardiac catheterization. It is important to make sure that the circulation to the hand is not compromised by radial artery resection. The subjective Allen test is used to perform assessment of the integrity of the palmar arch. Results are often equivocal. The Pulse Flowmeter might be used to perform a "Quantitative" Allen test. We have already built small, finger sized electrodes and they work perfectly well.

Cardiac Output Monitoring

It is often desirable to monitor cardiac output, particularly during surgery or when managing critically ill patients. Current methods involve complex and invasive techniques such as thermodilution and mixed venous oxygen saturation measurement. While the Pulse Flowmeter does not measure cardiac output, there is a close relationship between peripheral vascular flow and cardiac output, suggesting that the device may also have applications similar to the monitoring of cardiac output. Click to see data from patients given drugs to change cardiac output.


The Pulse Flowmeter may be a useful adjunct in the management of patients with hypertension as it might be used for titrating anti-hypertensive drug doses and distinguishing between the reactions to excessive levels of native vasoconstrictors and abnormal vascular non-compliance.