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A Shennan

Publications and source records attributed to A Shennan.

At least 37 records · Page 2Linked to original sources
PubMed1996

Lack of reproducibility in pregnancy of Korotkoff phase IV as measured by mercury sphygmomanometry.

BACKGROUND: Since hypertensive disorders of pregnancy are common, blood pressure is frequently measured in all pregnant women. Many authorities recommend that Korotkoff phase IV (K4, muffling of sound) is taken as the diastolic identification point measured on mercury sphygmomanometry in pregnancy because of reports that phase V (K5, disappearance of sound) is at or near to zero cuff pressure in some pregnant women. We compared the identification and reproducibility of K4 and K5 by observers unaware of each other's results. METHODS: In the first part of the study, two pairs of observers each took 340 measurements in 85 pregnant women. The second part of the study consisted of 1120 measurements in 80 pregnant and 80 non-pregnant women by five pairs of observers. Measurements were taken simultaneously by sphygmomanometry with a shared cuff and diaphragm; the observers were in separate booths. FINDINGS: K5 was identified in all measurements by both observers and never approached zero. K4 was heard in only 52% of measurements; in 33% of cases it was heard by only one of the pair of observers, so the pair agreed on its detection in only 19% of readings. Visual analogue scores used to assess Korotkoff sound quality indicated that systolic blood pressure was perceived significantly more clearly than diastolic blood pressure (K4 or K5). Even when K4 was heard by both observers, agreement on its value was poor (78% within 5 mm Hg vs 86% for K5, p < 0.05). K4 was heard significantly less often in non-pregnant women (32% of measurements). There was also no consistency in the identification of K4 within individual women. INTERPRETATION: K4 has little value in clinical management because it cannot be reproduced accurately. We recommend that K4 should be replaced by K5 as the measure of diastolic blood pressure in pregnancy.

Blood Pressure↗
PubMed1996

Diurnal blood pressure difference in the assessment of preeclampsia.

OBJECTIVE: To evaluate diurnal variation in blood pressure (BP) in normal gravidas and those with preeclampsia, using ambulatory BP monitoring. METHODS: A cross-sectional comparative observational study was performed in three teaching hospital maternity units. Twenty-four normotensive and 24 preeclamptic women who were similar in age, weight, and mean duration of gestation (35 weeks) were studied. Diurnal variation and BP measurement were assessed using ambulatory BP monitors validated for use in pregnancy and for which normal reference ranges for pregnancy have been derived. RESULTS: At night, the BP fall was less in preeclamptic women than in normotensive women. The day-night BP difference decreased as average BP rose (diastolic gradient = -0.54 [95% confidence interval (CI) -0.77 to -0.31], systolic gradient = -0.36 [95% CI -0.58 to -0.14], where gradient denotes a unit increase in BP leading to an increase or decrease in the day-night difference). CONCLUSION: The decrease in day-night BP difference observed in preeclampsia is inversely related to average BP. This blunting of the day-night BP difference may be a useful adjunctive measure of disease severity in preeclampsia.

Adolescent↗
PubMed1996

Hypertension in pregnancy: which method of blood pressure measurement is most predictive of outcome?

OBJECTIVE: To determine the clinical effectiveness of blood pressure (BP) measurement using conventional sphygmomanometry in the antenatal clinic and obstetric day unit compared with automated BP monitoring at home. METHODS: The study population consisted of 109 nulliparous white women with BPs of at least 140 or 90 mmHg at the antenatal clinic after 20 weeks' gestation, who underwent obstetric day unit and 24-hour automated BP monitoring on the same day. Automated measurement was obtained every half hour for 24 hours using a commercially available device that had been previously validated in pregnancy. RESULTS: At the traditional BP cutoff point (140/90 mmHg), the relative risk for subsequent development of adverse obstetric outcome was greatest for automated BP measurement: The relationships between outcome and automated diastolic BP were all statistically significant: proteinuria (P = .034), preterm delivery (P < .001), birth weight below the tenth percentile (P = .001), admission to the special care neonatal unit (P = .001), and cesarean delivery (P = .007). CONCLUSION: Automated BP measurement appears to improve the identification of patients who are at high risk of poor obstetric outcome. Automated BP measurement is worthy of further evaluation as an antenatal screening and diagnostic test.

Adolescent↗
PubMed1995

Blood pressure changes during labour and whilst ambulating with combined spinal epidural analgesia.

OBJECTIVE: To determine the influence of combined spinal epidural analgesia with fentanyl and low dose bupivacaine on maternal blood pressure and pulse rate in labour. Also, to evaluate the maternal cardiovascular response to mobilising with this form of analgesia in labour. Finally, to define the changes that occur in blood pressure and pulse rate during the second stage of labour and immediately postpartum when using combined spinal epidural analgesia. DESIGN: A prospective observational study. SUBJECTS AND METHODS: Blood pressure and pulse measurements were made at least every 10 minutes, using the SpaceLabs 90207 ambulatory blood pressure monitor, on 62 women in labour with combined spinal epidural analgesia. RESULTS: A significant fall in systolic blood pressure (> 20%) occurred in eight women (12%), all within 30 minutes of the spinal injection. Fifty-two women subsequently received an epidural dose (mean interval 90 minutes after spinal) and none of these women had a fall in systolic blood pressure of greater than 20%. No women had symptoms related to hypotension. Thirty-five women ambulated for more than 10 minutes on 65 occasions. Average blood pressure remained unchanged while ambulating (126/79 versus 126/79), but pulse rate was significantly increased (85 to 90, P < or = 0.001). The mean blood pressure in the second stage of labour (n = 41) did not rise with pushing (134/83 versus 134/83), but the pulse rate increased significantly (94 to 108, P < or = 0.001). Blood pressure remained unchanged immediately postpartum (n = 33) (134/83 versus 134/81) following ergometrine administration. CONCLUSION: The combined spinal epidural analgesia will only result in significant falls in systolic blood pressure within 30 minutes of the spinal injection. No further important changes in blood pressure occur when mobilising or with epidural top-ups. The combined spinal epidural analgesia may modify the normal compensatory mechanisms of blood pressure control, but does not cause significant maternal hypotension once the spinal injection has been given.

Analgesia, Epidural↗
PubMed1986

Acute and chronic effects of sotalol and propranolol on ventricular repolarization using constant-rate pacing.

Sotalol and propranolol were administered both intravenously and orally in conventional equipotent beta-blocking doses to 8 patients with permanent programmable ventricular pacemakers to study their effects on ventricular repolarization. Sotalol prolonged the QT interval by 6.5% (430 to 455 ms) after intravenous administration (p less than 0.01) and by up to 11.5% (430 to 483 ms) after 4 weeks of oral treatment (p less than 0.001). This was entirely due to prolongation of the JT interval, since there was no effect on QRS duration. The magnitude of QT and JT prolongation related to the serum level but the correlation was not statistically significant. QT prolongation was exaggerated after chronic treatment despite lower serum levels of sotalol (2.0 micrograms/ml) compared with levels after acute administration (3.5 micrograms/ml). After propranolol was given, there was no consistent change in QT or JT intervals, and although there was a tendency to slight prolongation of QT interval, by 2.5% after chronic oral administration, this was not statistically significant. This suggests that the prolongation of ventricular repolarization by sotalol is not caused by beta-blockade, but by its class III activity, and that chronic treatment increases the effect. There was no significant effect on chronic ventricular pacing threshold after intravenous or oral administration of either drug.

Adult↗
PubMed1985

Mode of delivery in the low birth weight fetus. Delivery by cesarean section independent of fetal lie versus vaginal delivery in vertex presentation. A study with long-term follow-up.

In a paired controlled multicenter study of patients in preterm labor of unknown etiology without additional maternal or fetal complications, 59 low birth weight infants in vertex presentation born vaginally were compared with 59 infants delivered by cesarean section. In the early postpartum period, hypothermia and acidosis occurred more often in the vaginal delivery group. The rate of respiratory disorders and need for assisted ventilation did not differ between the groups. Persistent ductus arteriosus occurred in 19% in the vaginal delivery group and in 7% in the abdominal delivery group. At follow-up until 18-24 months of age the rate of cerebral palsy did not differ between the groups, whereas the rate of psychomotor retardation was significantly higher in the vaginal delivery group (p less than 0.05). The difference in percentage of total outcome, i.e. sum of mortality and neurodevelopmental sequelae, being 20.3% in the vaginal delivery group versus 8.5% in the cesarean section group, fails to reach a statistical significance, but the results suggest that for the low birth weight infants, vaginal delivery may be more hazardous than abdominal delivery.

Adult↗