A heterodyne ultrasound blood velocity meter

SUMMARY1. An improved Doppler ultrasound technique was used to measure stroke volume (SV) and cardiac output (CO) on a beat-to-beat basis in a group of supine humans before, during and after periods of standardized, rhythmic exercise, involving the quadriceps muscle groups on both sides. The development of CO on such bouts of exercise was compared to Doppler ultrasound records of the simultaneous femoral arterial flow (FF) response.2. Records of CO at rest revealed spontaneous fluctuations around a mean level, with differences between the minimal and maximal values of the order of 11 min'. The mean CO level at rest again varied considerably from one day to another and from test run to test run.3. Upon start of exercise an immediate and rapid increase in heart rate (HR) and CO took place. The entire increase, the size of which varied appreciably from test run to test run, was completed within 10-15 s. No or only minor changes were seen in the mean SV level during the exercise periods.4. The time course of the increase in FF was indistinguishable from that of the increase in CO, which occurred without any detectable delay relative to the changes in FF. These closely parallel developments indicate a tight regulatory coupling between the two types of flow changes.5. In the majority of tests the total and two-sided increase in FF seen in the steady-state situation in the last part of an exercise period was significantly larger than the recorded increase in CO. This discrepancy implies that some redistribution of flow from tissues other than the working muscles might take place, even at this moderate level of work.

Section: Equipment and Techniquesmentioning

confidence: 99%

“…The UNIDOP instrument, which was operated in pulsed mode at 1-5 MHz, has been described in detail by Hatteland & Eriksen (1981). The output of this instrument's average velocity estimator was processed in parallel with the cardiac output measurements, using the same beat-by-beat averaging routines as for the SD-100 measurements of femoral flow.…”

Section: Methodsmentioning

confidence: 99%

Dynamics and dimensions of cardiac output changes in humans at the onset and at the end of moderate rhythmic exercise.

Eriksen

Waaler

Walløe

et al. 1990

“…The Doppler-ultrasound velocity-meter, UNIDOP (Vingmed, Horten, Norway), used in the present investigation and the computer system for data analysis have been described in detail in previous publications (Wille, 1977;Guldvog, Kjaernes, Thoresen & Walloe, 1980;Hatteland & Eriksen, 1981;Pedersen, 1982).…”

Section: Instrument8 and Equipmentmentioning

confidence: 99%

The time course and magnitude of blood flow changes in the human quadriceps muscles following isometric contraction.

Wesche¹

1986

SUMMARY1. Blood velocities in the human femoral artery were measured using pulsed bidirectional Doppler-ultrasound equipment before, during and after single isometric contractions of the quadriceps muscle group.2. After contraction periods lasting more than 20 s (long) and of tensions from 10 % up to 75 % of maximal voluntary contraction (m.v.c.), an increase in blood velocities of seven to eight times the resting level was observed. Estimated maximal volume flow to the whole leg during the post-contraction hyperaemic phase calculated from these blood velocity measurements and vessel diameter (measured with echoultrasound equipment) was in two of the subjects 2-4 1/min (female) and 4-4 1/min (male), respectively. In the latter, this estimate fitted very well with results obtained using a venous thermo-dilution method. When using computer tomography to estimate the volume of the quadriceps muscle group, the calculated maximum flow to this muscle group in the post-contraction hyperaemic phase was approximately 175 (female) and 185 (male) ml/min. 100 ml muscle, respectively. This was about forty times the estimated resting volume flow to this muscle of 4-7 (female) and 4'5 (male) ml/min. 100 ml muscle.3. The length of the post-contraction hyperaemia after short (< 10 s) contraction periods was 12-13 s, by which time velocities had reached 25 % above the precontraction level. After long contractions, the corresponding values were 23-25 s. By contrast, previous plethysmographic observations by others indicate that postcontraction hyperaemias following long contractions last 10-15 min.4. There was a marked difference between the times taken to reach maximal velocity in the hyperaemic phase when comparing short and long contractions. Maximal velocity was reached four to six cardiac cycles following short periods of contraction but during the very first heart beat after long periods of contractions. 5. The present observations are compatible with the hypothesis that locally released metabolites or hormones play a dominant role in the regulation of the post-contraction hyperaemia. Since during the short contraction periods maximal velocity was reached only after some seconds, whereas with the longer contraction periods it was reached during the first heart beat, it is suggested that these metabolites are released at some distance from the resistance vessels and that some time is needed for diffusion.

“…The computer systems for data collection and analysis have been described elsewhere (Hatteland & Eriksen, 1981;Wille, 1977). With the ultrasound transducer we could take measurements on any vessel with an internal diameter greater than 0-1 cm and within the depth range 0-2-2-5 cm, be it located in the neck, face or that part of the brain underlying a fontanelle.…”

Section: Methodsmentioning

confidence: 99%

An evaluation of the plethysmographic method of measuring cranial blood flow in the new‐born infant.

Cowan¹,

Eriksen²,

Thoresen³

1983

SUMMARY1. Cranial blood flow values obtained plethysmographically in the human new-born infant have been very variable and frequently very low. We have used a doppler ultrasound velocitymeter and skull compliance measurements to investigate whether the technique itself affects the cranial arterial inflow and whether the methods of calculation used introduce bias.2. Blood velocities were measured in intracranial and extracranial arteries during plethysmography, i.e. before, during and after jugular vein compressions of short duration. Skull expansion after tilting was used to estimate skull compliance.3. In about 10 % of jugular vein compressions, arterial velocities decreased immediately, due to direct pressure on the carotid artery. In the remaining compressions a fall in arterial velocities was seen four or five heartbeats after the onset of the compression. This was probably caused by a decrease in the cranial perfusion pressure consequent on rising venous pressure.4. Some babies demonstrated very poor skull compliance and these babies had correspondingly low estimates of cranial blood flow.5. We conclude that jugular venous occlusion plethysmography is not a suitable method for use in the clinical field and is only useful as a research tool in carefully selected situations.