No abstract

We combined two ultrasound techniques to develop a safe, non-invasive, transcutaneous method of observing the circulation in the umbilical arteries and vein in the fetus. The umbilical cord can be located by standard echo ultrasound procedures, and this information can be used to direct a Doppler ultrasound beam on to the vessels in the cord. The signals can be heard through audio headphones or recorded on a tape recorder and spectrum-analysed. The method was successful in each of 20 patients examined, whose pregnancies ranged from 12 to 40 weeks' gestational age, and was suitable for outpatient use. It should be useful in assessing such conditions as pre-eclampsia and intrauterine growth retardation. FIG 1-B-scan showing umbilical cord (UC) of 12-week-old fetus and displaying the echoscan depth-markers (EM).

Summary A combination of pulsed echo and continuous wave Doppler ultrasound was used to obtain blood flow velocity signals from the umbilical arteries of 18 normal patients from the 16th until the 40th week of pregnancy. Audio frequency analysis of these signals yielded fetal blood velocity waveforms. Analysis of these waveforms demonstrated that the placenta is an organ of low vascular resistance and that placental resistance to blood flow declines with advancing gestational age in normal pregnancy.

SUMMARY Baroreflex function was assessed in elderly hypertensive patients and compared with that observed in young hypertensives and young normotensives. Mean arterial pressure was reduced by 20% using intravenous nitroprusside infusion in 10 elderly hypertensive patients (older than 65 years and diastolic pressures over 95 mm Hg), in 10 young hypertensives (under 60 years and diastolic pressures over 95 mm Hg), and in seven young normotensive subjects (under 60 years and diastolic pressures under 95 mm Hg). Elderly subjects demonstrated greater sensitivity (p < 0.005) and greater variability of response (p < 0.025) to nitroprusside than either young group. There was no significant difference between the slight heart rate increases observed in the supine position in the three groups. However, in the erect position, heart rate increases were significantly less in the elderly hypertensive group than in the young hypertensive group (p < 0.01) or the young normotensive group (p < 0.005). Furthermore, the slope of the regression line relating change in blood pressure with change in R-R interval was less for the elderly patients than for the young hypertensives (p < 0.05) or the young normotensives (p < 0.025). We conclude that the heart rate component of the baroreflex is impaired in elderly hypertensives, and anticipate that the clinical response to antihypertensive drugs will be altered. (Hypertension 5: 763-766, 1983) KEY WORDS * nitroprusside * heart rate • aging A GING is associated with alteration in many physiological systems that can respond to drugs. 1 Previous workers have shown altered response in the cardiovascular system to various pharmacological agents.2 " 3 Baroreflex activity, which is important in cardiovascular homeostasis, has been shown to decline with increasing arterial pressure 67 and with increasing age up to 66 years. 8 However, no information is available in older hypertensive patients. Since impaired baroreflex function in such patients would have important therapeutic implications, we assessed some aspects of the baroreflex by studying blood pressure and heart rate response to nitroprusside in a group of such patients, and comparing the results with those observed in young hypertensives and young normotensives. Methods and MaterialsThree groups of patients were studied -elderly hypertensives, young hypertensives, and young normotensives. The elderly hypertensives were all older than 65 years, with ages ranging from 66 to 80 years. Diastolic pressures were greater than 95 mm Hg in each case. The supine mean arterial pressure (diastolic pressure + Vi pulse pressure) ranged from 115 to 154 mm Hg, and the erect mean arterial pressure ranged from 113 to 160 mm Hg. The mean baseline supine heart rate was 74.9 ± 2.9 beats min~' and the mean erect heart rate was 77.3 ± 2.9 beats min." 1 . The young hypertensives were under 60 years of age -ranging from 32 to 56 years. Their diastolic pressures were greater than 95 mm Hg, with supine mean arterial pressures ranging from 114 to 135 mm Hg and ...

A transcutaneous technique is described utilizing two ultrasonic Doppler‐shift flow‐velocity meters simultaneously at sites down the arterial system of the leg in patients with superficial femoral disease. The change in shape of the blood‐velocity/time wave‐form over the cardiac cycle and the pulse propagation time between the two sites are measured. The transit time and change in pulse shape are used to assess limb viability. This method is compared with two other non‐invasive techniques: whole‐limb flow measured by a strain‐gauge plethysmograph and with the systolic pressure difference between the arm and the calf. It is shown that as the pulse propagation time and the degree of damping of the blood‐velocity/time wave‐form increase, then limb perfusion decreases, and a nomogram is presented relating these parameters.