Fetal echocardiography during indomethacin treatment

Fetal echocardiograms were evaluated in 315 studies performed in 107 fetuses exposed to indomethacin. In the majority of cases, the results of the fetal echocardiography study were within normal limits (74%). The most common abnormal phenomena were tricuspid valve regurgitation (10%), ductal constriction (6%), tricuspid valve regurgitation and ductal constriction (5%), an increased ductal velocity (2%), and other (3%). The difference between the prevalence of ductal constriction in the whole series of studies (11%) compared to the prevalence of ductal constriction per fetus (25%) (p < 0.001) suggests that this phenomenon was only temporary and disappeared when medication was discontinued. The mean gestational age for detection of tricuspid valve regurgitation was 27.7 +/- 2.8 weeks and for ductal constriction, 30.9 +/- 2.1 weeks (t-test, p < 0.01). Trivial tricuspid valve regurgitation was detected at a mean of 26.7 +/- 2.2 weeks and significant tricuspid valve regurgitation at 29.6 +/- 2.3 weeks (t-test, p < 0.01). We conclude that indomethacin treatment is relatively safe for the fetal heart. The most common side-effects are tricuspid valve regurgitation and ductal constriction. Tricuspid valve regurgitation may be detected before ductal constriction, but by itself it is not a contraindication for the continued use of indomethacin.

Monitoring complication due to a pulsatile femoral vein from tricuspid regurgitation

This clinical report illustrates a monitoring complication due to a pulsatile femoral vein from tricuspid regurgitation. In this case, the femoral vein of a patient was inadvertently cannulated and exhibited a pulsatile tracing which was mistaken for an arterial pressure tracing. This led to the initial inappropriate use of vasopressors which actually augmented the pulsatility and delayed detection of the error. Although this may be a rare occurrence, the clinician should be aware of its possibility when using invasive monitoring in a patient with tricuspid regurgitation.

The effect of a cerebral vasodilator, vinpocetine, on cerebral vascular resistance evaluated by the Doppler ultrasonic technique in patients with cerebrovascular diseases

Changes in cerebral vascular resistance were examined in patients with cerebral circulatory diseases by the Doppler ultrasonic technique after administration of a cerebral vasodilator, vinpocetine, for two months. Continuous index (CI) and pulsatility index (PI) of the blood flow pattern in the internal carotid artery were used as objective parameters for changes in cerebral vascular resistance. 1. The CI and PI changed significantly after administration of the drug; ie, the CI increased while the PI decreased. 2. An inverse correlation was noted between the rate of change of the CI (delta CI) and that of the PI (delta PI). 3. The results suggest that measurement of the CI and PI by the Doppler ultrasonic technique is useful in investigating the effect of drugs on the cerebral circulation.

Starch microspheres induce pulsatile delivery of drugs and peptides across the epithelial barrier by reversible separation of the tight junctions

Non-parenteral administration of peptide drugs is prevented by the limited permeability of the epithelia lining the mucosal tissues. As a new approach to non-parenteral delivery, degradable starch microspheres (dsm) were coated with insulin and administered to the mucosal side of monolayers of human intestinal epithelial (Caco-2) cells in vitro. The microspheres induced a pulsed delivery of insulin across the epithelium that lasted for 1-2 h. The pulsed delivery correlated with a reversible appearance of focal dilatations in the tight junctions between the epithelial cells, indicating that dsm enhance the delivery of insulin by the paracellular route. These results provide an explanation for the previously observed absorption enhancing properties of dsm.

Effect of dehydroepiandrosterone sulfate on uterine artery flow velocity waveforms in term pregnancy

OBJECTIVE

To investigate the interrelation between estrogen synthesis by the fetoplacental unit and uteroplacental hemodynamics in term pregnancy.

METHODS

Transvaginal color Doppler flow imaging and pulsed Doppler ultrasonographic assessments were made on ten normal full-term pregnant women before and 3, 5, 10, 30, and 60 minutes after the administration of a 200-mg intravenous dose of dehydroepiandrosterone sulfate (DHAS) in 20 mL of 5% dextrose. Ten normal full-term pregnant women received 20 mL of 5% dextrose as controls. The pulsatility index (PI) values for the uterine artery, heart rate, and mean arterial pressure were recorded. Plasma estradiol (E2) was measured before and 10 minutes after the infusion.

RESULTS

In the DHAS group, uterine artery PI decreased from baseline by 26% (P < .05) after 5 minutes, and the mean reduction was 36% (P < .05) after 10 minutes and 15% (P < .05) after 30 minutes. The PI returned to the baseline value 60 minutes later. In the control group, there was no change in uterine artery PI. No change was found in heart rate or mean arterial blood pressure in the control or DHAS groups. The mean plasma E2 increased from 22.3 +/- 6.6 to 56.2 +/- 24.1 ng/mL (P < .05) 10 minutes after the infusion in DHAS subjects, whereas there was no significant change in plasma E2 in the controls.

CONCLUSION

Dehydroepiandrosterone sulfate induces a significant decrease in the uterine artery PI, which suggests a possible decrease in uterine vascular impedance in term pregnancy.

Effects of naloxone on pulsatile luteinizing hormone in experimental hyperprolactinemia

It is well known that opioids regulate luteinizing hormone (LH) secretion through not fully understood mechanisms. This study describes the effects of naloxone on the episodic release of LH in adult sham-operated and pituitary-grafted female rats. Animals were rendered hyperprolactinemic by transplanting 2 pituitary glands beneath the kidney capsule. Naloxone (2 mg/kg/h) or saline (0.5 ml/h) were administered iv through jugular cannulae and subjects were bled at 7 min intervals for a period of 3 h. As expected, pituitary-grafting was followed by an increase in mean values of prolactin during the bleeding period. Naloxone administration decreased mean serum prolactin levels in sham-operated rats and did not further change them in pituitary-grafted animals. Hyperprolactinemia was associated with increases in mean serum LH levels during the bleeding period and in the absolute amplitude of LH peaks. Naloxone administration increased mean values of LH and the absolute amplitude of LH peaks, and decreased their frequency in sham-operated rats. Neither pituitary grafting nor naloxone administration modified the frequency, duration or relative amplitude of LH peaks. However, naloxone administration reduced the mean half-life of LH in sham-operated rats to a similar extent than did pituitary grafting. Naloxone failed to further change the mean half-life of LH in pituitary-grafted rats. These results suggest that opioids modulate the pulsatile pattern of LH and that these effects are blunted in pituitary-grafted animals.

Opioids and the pulsatile prolactin secretory pattern: effects of hyperprolactinemia

It is well known that opioids regulate prolactin secretion through unknown mechanisms. The present study describes the effects of morphine and naloxone administration on pulsatile prolactin secretion in adult sham-operated and pituitary-grafted female rats. Animals were rendered hyperprolactinemic by transplanting 2 pituitary glands beneath the kidney capsule. Naloxone (2 mg/kg/h), morphine (50 mg/kg/h)+naloxone or saline (0.5 ml/h) were administered i.v. through a jugular cannula and bled at 7-min intervals for a period of 3 h. Pituitary grafting increased mean serum prolactin levels, the absolute amplitude and the duration of the pulses, but decreased their frequency. Naloxone, in sham-operated rats, reduced mean serum prolactin levels, the absolute amplitude and the frequency of the pulses. However, morphine+naloxone administration increased mean serum prolactin levels and the absolute amplitudes of prolactin pulses in pituitary-grafted rats. Naloxone administration did not decrease previously increased mean serum levels of prolactin in pituitary-grafted rats. These results suggest that opioids synchronize the pulsatile pattern of prolactin and that these effects are blunted in pituitary-grafted animals.

Uterine and umbilical blood flow velocity during epidural anaesthesia for caesarean section

The purpose of this study was to use colour Doppler to determine the effect of epidural anaesthesia on the uterine and umbilical blood flow velocities. After determining the precision of the technique, Doppler insonation of the uterine and umbilical arteries was performed in consenting non-labouring patients requesting epidural anaesthesia for Caesarean section. Patients in Group I were normal and those in Group II were at high risk for uteroplacental blood flow abnormalities. The pulsatility indexes (PI) of both uterine and umbilical arteries were compared at the following times: control, after fluid and after anaesthesia using repeated measure analysis of variance. In Group I (n = 30) the PI increased from 0.72 to 0.82 in the left uterine artery and from 0.71 to 0.85 in the right uterine artery (P < 0.05). In Group II (n = 10) the PI increased from 0.67 to 0.85 in the left uterine artery (NS) and from 0.98 to 1.38 in the right uterine artery (P < 0.05). There was no change in the PI in the umbilical artery. We conclude that the PI of the uterine arteries increases after epidural anaesthesia with lidocaine, epinephrine and fentanyl but there is no change in the umbilical PI. While these changes do not appear to be clinically important in the low-risk population, further studies are required to determine the impact on fetuses at high risk for in utero hypoxaemia.

Cocaine effects on pulsatile secretion of ACTH in men

The effects of cocaine on pulsatile secretion of adrenocorticotropic hormone (ACTH) in men were studied under controlled clinical research ward conditions. Eight men with a Diagnostic and Statistical Manual of the American Psychiatric Association Version III, revised, diagnosis of concurrent cocaine and opioid dependence provided their informed consent for participation in this study. After an overnight fast, a challenge dose of cocaine (30 mg i.v.) or placebo was administered under single-blind conditions in a randomized order on 2 study days. Blood samples were collected at 2-min intervals for 76 min during base line and for an additional 76 min after i.v. administration of the challenge dose. Peak plasma cocaine levels of 313.8 +/- 46.5 ng/ml were detected within 2 min after cocaine administration. The cluster analysis program originally described by Veldhuis and Johnson (1986) was used to characterize ACTH pulsatile secretion (Iranmanesh et al., 1990). Acute cocaine administration (30 mg i.v.) significantly increased ACTH mean peak amplitude (P < .05), mean percent increase in peak amplitude, (P < .05), mean peak area (P < .04), total peak area (P < .04) and incremental peak height (P < .04). Mean ACTH valley levels (P < .02) and mean valley nadir (P < .02) were also significantly increased after cocaine administration. We postulate that cocaine stimulates the release of corticotropin releasing factor and that the cocaine-induced secretion of corticotropin releasing factor increases the amplitude of ACTH pulses, because ACTH pulse frequency was not altered by cocaine.

Patterns of cerebrovascular reactivity in patients with unilateral asymptomatic carotid artery stenosis

BACKGROUND AND PURPOSE

Intracranial hemodynamic status varies in patients with unilateral significant carotid artery stenosis. It ranges from normal, because of sufficient collaterals, to poor, because of a severely reduced blood supply that puts the patient at an increased risk of stroke or cerebral ischemia. The present study examined patterns of abnormal cerebrovascular hemodynamics in patients with asymptomatic carotid artery stenosis.

METHODS

The CO2 reactivity of the cerebral resistance index (CRi) and of mean blood flow velocity (vmean) was determined via transcranial Doppler sonography in 91 patients with unilateral high-grade to threadlike carotid artery stenosis and in 37 control subjects. The interhemispheric asymmetry of CRi reactivity of the control group was used to differentiate between normal and abnormal findings.

RESULTS

We found that 64.8% of the patients demonstrated normal CRi asymmetry with comparable CRi reactivity (ipsilateral, 4.42 +/- 0.44 %CRi/vol%CO2; contralateral, 4.51 +/- 0.39 %CRi/vol%CO2) and vmean reactivity (ipsilateral, 0.080 +/- 0.004 m/s per vol%CO2; contralateral, 0.079 +/- 0.005 m/s per vol%CO2) at both hemispheres. In 16.5% of the patients, CRi reactivity was supranormal at the affected hemisphere. This phenomenon was due to an exaggerated dilatory response of the ipsilateral hemisphere and was combined with an absent CRi reactivity of the contralateral hemisphere (ipsilateral, 6.63 +/- 1.03 %CRi/vol%CO2; contralateral, -1.16 +/- 1.78 %CRi/vol%CO2). In contrast, hemispheric vmean reactivities were comparable (ipsilateral, 0.078 +/- 0.008 m/s per vol%CO2; contralateral, 0.077 +/- 0.008 m/s per vol%CO2). The remaining 18.7% showed severely diminished ipsilateral CRi reactivity (ipsilateral, 1.91 +/- 0.83 %CRi/vol%CO2; contralateral, 8.48 +/- 1.00 %CRi/vol%CO2) and vmean reactivity (ipsilateral, 0.073 +/- 0.007 m/s per vol%CO2; contralateral, 0.108 +/- 0.012 m/s per vol%CO2; P < .01), compatible with a significantly reduced perfusion pressure at the poststenotic hemisphere.

CONCLUSIONS

Most asymptomatic patients do not suffer from severely abnormal hemodynamics at the poststenotic hemisphere. One small subgroup of patients presented with severely disturbed ipsilateral hemodynamics; another small subgroup demonstrated a steal phenomenon with secondary dilation of large cerebral vessels at the contralateral hemisphere. These subgroups require specific evaluation of proper treatment.

Effects of pentoxifylline on choroidal blood flow in nonproliferative diabetic retinopathy

OBJECTIVE

Diminished blood flow plays an important role in the progression of diabetic retinopathy. Since increased blood viscosity is a contributing factor to hypoperfusion, it was of interest to determine whether therapy intended to decrease blood viscosity and induce vasodilation could increase blood flow in patients with diabetic retinopathy.

METHODOLOGY

Ten patients, 4 with nonproliferative diabetic retinopathy and 6 age-matched, nondiabetic controls, were studied by a noninvasive system to index choroidal blood flow. Pentoxifylline was administered daily at an oral dose of 400 mg tid in the diabetic patients for nine months.

RESULTS

The control group had pulse amplitude = 2.87 +/- 0.67 mm Hg with pulsatile choroidal blood flow = 714 +/- 196 microL/minute. Reproducibility studies in the control group (6 patients measured on three separate occasions) demonstrated an intraclass correlation coefficient of reliability, r = 0.83. In the diabetic patients, pulsatile flow = 276 +/- 68 microL/minute, 61% lower than the age-matched nondiabetic subjects (P = 0.003). After nine months of pentoxifylline therapy the diabetic patients had an increase in pulsatile choroidal blood flow to 469 +/- 152 microL/minute (P < 0.002).

CONCLUSIONS

Pentoxifylline therapy brought blood flow levels in the diabetic patients closer to those of the nondiabetic age-matched control population so that following therapy there was no statistically significant difference between the two groups although the former were still lower. The potential efficacy of pentoxifylline in improving ocular blood flow in patients with diabetic retinopathy should be tested in a large controlled clinical trial.

Differences in the longterm effect of timolol and betaxolol on the pulsatile ocular blood flow

In the past several years the effect of longterm glaucoma therapy on ocular hemodynamics has taken on increased interest. This interest has been sparked by studies demonstrating differential effects of various beta-blockers on visual function, and the possible contributory role of ocular blood flow. In the present study, the pulsatile ocular blood flow (POBF), as derived by the Langham OBF system, was measured prior to treatment and then tracked throughout a one-year period of beta-blocker therapy (betaxolol 0.5% or timolol 0.5%) in 25 glaucoma patients. Results of the two treatments were compared, and indicated that, whereas both betaxolol- and timolol-treated patients had similar significant reductions in the IOP, the effect of the two treatments on the POBF differed. In timolol-treated patients, the POBF decreased significantly over the 12-month observation period, whereas in betaxolol-treated patients it remained stable.

The effects of regional anaesthesia for caesarean section on maternal and fetal blood flow velocities measured by Doppler ultrasound

We studied the effects of spinal anaesthesia (Group S), epidural anaesthesia (Group E), and combined spinal and epidural anaesthesia (Group SE), on maternal and fetal blood flow in 24 healthy parturients (n = 8/group) with uncomplicated singleton pregnancies using Doppler technique. Prior to the induction of anaesthesia, the patients were prehydrated with balanced electrolyte solution 15 ml.kg-1 over a period of 15 min. After the induction of regional anaesthesia, the systolic blood pressure was maintained within 15% limits of the preoperative values using prophylactic etilefrine infusion in Groups S and SE. The flow velocity waveforms of the maternal femoral artery, the main branch of the uterine artery (placental side), the foetal umbilical and middle cerebral arteries were recorded by Doppler technique before and after prehydration as well as after onset of T7 analgesia and the pulsatility indices (PI) were derived. Rapid intravenous prehydration had no effects on uteroplacental or fetal circulation as indicated by unaltered uterine, umbilical, and fetal middle cerebral artery PIs. After the onset of T7 analgesia, the uterine artery PI was increased in Group S indicating increased uterine vascular resistance while no changes occurred in Groups E and SE. No adverse effects were observed on the neonates as indicated by the Apgar score and the umbilical artery and vein acid-base status in any of the groups.

Does a paracervical block with bupivacaine change vascular resistance in uterine and umbilical arteries?

Paracervical block during labor following normal, uncomplicated pregnancy is occasionally accompanied by fetal bradycardia. To evaluate whether a paracervical block with bupivacaine causes changes in the vascular resistance of uteroplacental and umbilicoplacental blood flow, a total of 12 singleton, uncomplicated pregnancies in active labor at the end of pregnancy were included to this study. By using pulsed color Doppler ultrasound techniques the pulsatility indices were measured from both uterine and umbilical arteries before, one minute and 20 minutes after a paracervical block with bupivacaine. Pulsatility indices of both uterine and umbilical arteries remained unchanged throughout the study period, as did fetal and maternal heart rates. In two cases fetal bradycardia developed, causing a marked increase in the vascular resistance of the umbilical artery one minute after the paracervical block. In the uterine arteries there was only a minor increase. When the fetal bradycardia ceased the pulsatility indices returned to the levels at the beginning of the study. Paracervical block with bupivacaine in normal pregnancies without signs of chronic or acute fetal distress does not change the vascular resistance in the uterine or umbilical arteries. If fetal bradycardia develops, it seems to be due to the direct effect of bupivacaine on the fetus, mainly on the umbilical vessels.

Acute effect of topical carteolol on ocular pulsatile volume change

To determine whether topical carteolol affects ocular blood flow, we studied effects of carteolol 2% on the ocular pulse waves in 9 normal volunteers, and analyzed the results as variations in pulsatile volume changes (PVC) for one minute (PVCm) using the Friedenwald's pressure-volume relationship. PVC means a volume for the pressure amplitude in each pulse. The pulse waves were recorded with a pneumatonometer and analyzed by a computer. The PVCm change 15 min after the carteolol instillation was evaluated with the control performed with biological salt solution in the same manner. The data showed a net increase in the PVCm of the carteolol-instilled eyes (21.3 +/- 6.4 microliters/min: mean +/- standard error, p < 0.05, paired t-test). Considering a finding that PVCm takes 50% of the total ocular blood flow, the results suggest a possible alteration in the total flow by a carteolol instillation.

The effects of pentoxifylline on the relative perfusion of tumours growing in three sites in the mouse

The haemorheological agent pentoxifylline (PTX) has been shown to improve the relative perfusion and oxygenation of subcutaneous tumours in the mouse. In order to establish whether this effect is dependent on the site of tumour growth, we have looked at changes in the distribution of the cardiac output (COD) to the murine NT carcinoma grown either intradermally (i.d.), intramuscularly (i.m.), on the wall of the caecum, or in all three sites, following i.p. administration of 50 mg kg-1 PTX. In animals bearing a single tumour, PTX treatment significantly increases the COD to tumours located in the caecum, but has no significant effect on the COD to those located in the i.d. or i.m. sites. If all three tumours are present in a single animal, the COD to all three tumours is significantly enhanced by PTX. This appears to reflect the presence of the caecum tumour and does not appear to relate to changes in tumour size or to the haematocrit (HCT) of the blood. We propose that this site dependency implies that a significant increase in blood viscosity only occurs in animals with tumours located in specific sites. Therefore, the potential radiosensitising capability of PTX is highly dependent on tumour location.

Blood flow variations in internal carotid and middle cerebral arteries induced by postmenopausal hormone replacement therapy

OBJECTIVE

Our purpose was to clarify the mechanisms by which postmenopausal estrogen replacement therapy exerts its protective effect on cardiovascular risk.

STUDY DESIGN

By means of a bidirectional Doppler ultrasonographic system we measured pulsatility index variations the internal carotid artery and middle cerebral artery in 25 early postmenopausal women during a 6-month period of hormone replacement therapy. Transdermal estradiol (50 micrograms/day) was continuously administered. A 12-day course of medroxyprogesterone acetate (10 mg/day) was added every second month.

RESULTS

The pulsatility index showed a significant (p = 0.0001) reduction in both arteries after 6 weeks. At 22 weeks a 25% reduction was measured. No variation of the estrogen-induced pulsatility index reduction was observed at the end of every cyclic progestogen supplementation.

CONCLUSIONS

In early postmenopausal women hormone replacement therapy causes a rapid reduction of pulsatility index in brain arteries. Cyclical progestational supplementation does not modify this positive effect on reactivity of the blood vessels.

[Transcranial Doppler sonography as a reliable diagnostic tool in craniocerebral trauma]

Transcranial Doppler sonography (TCD) is a simple, noninvasive bedside procedure that can be repeated any time for the measurement of cerebral blood flow velocity in the great basal cerebral arteries. It is practicable in most severely head-injured patients in critical care. Flow patterns and pulsatility index (PI) resulting from maximal systolic and diastolic flow velocities and representing cerebrovascular resistance give quite an accurate impression of potential intracranial hypertension and the dependent cerebral perfusion pressure (CPP). With increasing intracranial pressure (ICP) and decreasing CCP, diastolic flow is progressively reduced. If ICP reaches the systemic diastolic blood pressure level, diastolic flow disappears. Oscillating (reverberating) flow patterns are seen when ICP increases further up to the arterial mean pressure level. The authors' own studies on 20 comatose patients with raised ICP showed typical changes in TCD parameters following different therapies for intracranial hypertension. Under continuous TCD monitoring of the middle cerebral artery, increases in maximal flow velocity (from 4% up to 102%, on average 27%) and mean flow velocity (from 18% up to 153%, on averaged 73%) were always observed after osmotherapy. In addition, a variable increase in negative frequencies was noted, probably due to increased turbulences. After barbiturate administration (thiopentone bolus of 0.3 g) a flow reduction was always seen [from -2% up to -25% (on average -13%) for maximal flow velocity and from -9% up to -30% (on average -19%) for mean flow velocity].(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of effects of felodipine versus hydrochlorothiazide on arterial diameter and pulse-wave velocity in essential hypertension

In a double-blind cross-over study, the arterial changes produced by hydrochlorothiazide were compared with those observed after the calcium antagonist felodipine in 16 patients with mild to moderate systemic hypertension. Diameter changes at the site of the common carotid and brachial arteries were investigated using pulsed Doppler velocimetry, and pulse-wave velocities of the aortic, brachial and femorotibial areas were measured using standard noninvasive techniques. Whereas hydrochlorothiazide and felodipine similarly decreased blood pressure, hydrochlorothiazide did not change pulse-wave velocity, and the diameters of the brachial and common carotid arteries. Felodipine significantly decreased pulse-wave velocity, and increased brachial arterial diameter and compliance, with no change in carotid arterial diameter. Evidence was found that although felodipine had specific effects on the arterial system of hypertensive subjects, hydrochlorothiazide did not produce any sizable arterial change. These differential effects may influence specifically the heart afterload, with important consequences for diuretics that are known to cause minimal changes in cardiac structure and function.

[Arterial vascular diagnosis by Doppler pulse curve analysis of the first dorsal metatarsal artery]

In patients with peripheral arterial occlusive disease diagnostics by Doppler-sonography at the toe arteries and by Doppler-pressure measurement at the ankle arteries is often difficult and sometimes impossible. Using the first dorsal metatarsal artery for Doppler-waveform analysis yields exact information on haemodynamically relevant circulatory disturbances. Painful ulcers, gangrene, oedemata, mediasclerosis, burns, plaster casts, posttraumatic or postoperative conditions prevent the application of cuffs at the lower leg or foot. This Doppler-waveform analysis evidently represents the degree and the specialties of a disturbed blood circulation and allows an additional assessment of the vessels distal from the ankle arteries and enables a functional test on the anastomosis of the artery tibialis posterior and the artery dorsalis pedis. Functional and pharmacological influences on the tone of the vessels can be shown. The typical diagnostic features of Doppler-wave-form analysis used at the proximal measuring points are also valid at the dorsal metatarsal artery. The results of own comparative investigations in 69 patients and 44 healthy test persons are demonstrated.

Uteroplacental and fetal circulation during extradural bupivacaine-adrenaline and bupivacaine for caesarean section in hypertensive pregnancies with chronic fetal asphyxia

We have studied the effects of an extradural block during Caesarean section using either bupivacaine plain or with adrenaline 85-100 micrograms on blood velocity waveforms of maternal uterine and placental arcuate arteries and fetal umbilical, renal and middle cerebral arteries, in 20 hypertensive parturients with chronic fetal asphyxia. Fetal myocardial function was investigated at the same time by M-mode echocardiography. Extradural anaesthesia resulted in a significant decrease in maternal mean systolic and diastolic arterial pressures in both groups, but this was more marked after plain bupivacaine. There were no significant differences in any of the Doppler recordings relative to baseline values after plain bupivacaine, but after bupivacaine with adrenaline there were significantly increased blood flow velocity indices for the maternal uterine and placental arcuate arteries and significantly decreased indices in the fetal renal and middle cerebral arteries. Neonatal outcome as evaluated by Apgar scores and acid-base values in the umbilical cord were similar in the two groups. The results suggest that adrenaline added to the solution of bupivacaine increased vascular resistance in the uteroplacental circulation, indicating impaired blood flow.

Cerebral blood flow and cerebral blood flow velocity during angiotensin-induced arterial hypertension in dogs

Pressure-passive perfusion beyond the upper limit of cerebral blood flow (CBF) autoregulation may be deleterious in patients with intracranial pathology. Therefore, monitoring of changes in CBF would be of clinical relevance in situations where clinical evaluation of adequate cerebral perfusion is impossible. Noninvasive monitoring of cerebral blood flow velocity using transcranial Doppler sonography (TCD) may reflect relative changes in CBF. This study correlates the effects of angiotensin-induced arterial hypertension on CBF and cerebral blood flow velocity in dogs. Heart rate (HR) was recorded using standard ECG. Catheters were placed in both femoral arteries and veins for measurements of mean arterial blood pressure (MAP), blood sampling and drug administration. A left ventricular catheter was placed for injection of microspheres. Cerebral blood flow velocity was measured in the basilar artery through a cranial window using a pulsed 8 MHz transcranial Doppler ultrasound system. CBF was measured using colour-labelled microspheres. Intracranial pressure (ICP) was measured using an epidural probe. Arterial blood gases, arterial pH and body temperature were maintained constant over time. Two baseline measures of HR, MAP, CBF, cerebral blood flow velocity and ICP were made in all dogs (n = 10) using etomidate infusion (1.5 mg.kg-1 x hr-1) and 70% N2O in O2 as background anaesthesia. Following baseline measurements, a bolus of 1.25 mg angiotensin was injected i.v. and all variables were recorded five minutes after the injection. Mean arterial blood pressure was increased by 76%. Heart rate and ICP did not change. Changes in MAP were associated with increases in cortical CBF (78%), brainstem CBF (87%) and cerebellum CBF (64%).(ABSTRACT TRUNCATED AT 250 WORDS)

[Effect of rapid mannitol infusion on middle cerebral artery blood flow velocity and pulsatility index--a transcranial Doppler ultrasonography study in monkeys]

Hemodynamic changes immediately after the administration of mannitol were investigated in monkeys (Macaca Fuscata) using transcranial Doppler ultrasound (TC2-64) and were compared with those after CO2 loading. The CO2 loading group was hyperventilated to an end-tidal PCO2 of 36.5 +/- 2.21 and hypoventilated to an end-tidal PCO2 of 46.3 +/- 2.69. Mean flow velocity in the middle cerebral artery (MCA-FV), Pulsatility index (PI) and blood flow in the internal carotid artery (IC-BF) studies were performed twice before and after hypercapnea. In the Mannitol group, Mannitol (2 g/kg) was infused at a rate 20 to 30 ml/min. MCA-FV, PI, IC-BF and intracranial pressure (ICP) studies were performed twice before administration and 10 minutes after administration of Mannitol. In the Mannitol group (n = 8), MCA-FV and IC-BF and ICP increased significantly after administration of Mannitol (p < 0.005, p < 0.005, p < 0.025), but there was no significant difference in the PI. In the CO2 loading group (n = 15), MCA-FV and IC-BF increased significantly (both p < 0.005) and PI decreased significantly (p < 0.005). These results indicated that, in the presence of normal autoregulation without intracranial hypertension, there was no change in the resistance of the peripheral cerebral vessels, while a decrease in viscosity after administration of Mannitol caused an increase in cerebral blood flow. Hence, according to Poiseuille's law, peripheral vasoconstriction occurred in the early period after administration of Mannitol. This change was considered to be due to autoregulation of the cerebral vessels.

The effect of topical pilocarpine on pulsatile ocular blood flow

Ocular blood flow is considered an important factor in determining the extent of visual damage occurring in primary open angle glaucoma (POAG). The effect of topical pilocarpine, a parasympathomimetic vasodilator, on the pulsatile ocular blood flow (POBF) in POAG subjects was studied. A pneumotonometer linked to the Langham Ocular Blood Flow System recorded the intraocular pressure (IOP) pulse from which POBF was calculated. Measurements were taken from 18 POAG subjects treated with both G pilocarpine and G timolol, 2 weeks after withdrawing G pilocarpine and again 1 week after reinstituting full treatment. Recordings from 20 POAG patients treated with only G timolol were taken as control values. There was no significant difference in the IOP or POBF between the controls and POAG patients on dual therapy. Furthermore when G pilocarpine was temporarily withdrawn there was no significant change in POBF despite a significant rise in IOP. The results imply that aqueous pilocarpine has no direct effect on the pulsatile component of ocular blood.