Recent developments in obstetrics.
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Breech Presentation↗
Biomedical subjects
Andrew H Shennan
Publications and source records attributed to Andrew H Shennan.
The Maxi Stabil 3: validation of an aneroid device according to a modified British Hypertension Society protocol.
BACKGROUND: Measuring blood pressure with mercury-independent alternatives is rapidly gaining attention. Mercury will be phased out of clinical use as a result of environmental, health and safety concerns and it is of vital importance that any alternative to mercury has to be of a recognized standard. We assessed the accuracy of the Maxi Stabil 3 aneroid device in an adult population according to a modified British Hypertension Society protocol (with the low systolic category changed from less than 90 mmHg to less than 100 mmHg). POPULATION: Eighty-five subjects were recruited from among staff and patients at Guy's and St Thomas' Hospitals, London, UK. METHODS: The aneroid device was connected in parallel to two mercury sphygmomanometers. Nine sequential same-arm measurements were taken from each subject by two trained observers, alternating between mercury sphygmomanometry and the aneroid device. Simultaneous mercury readings were also recorded for additional analysis. RESULTS: The device achieved an A grade for both systolic and diastolic pressures and fulfilled the requirements of the Association for the Advancement of Medical Instrumentation. The mean and standard deviation for systolic and diastolic pressures respectively were -0.6 (4.6) mmHg and -1.3 (3.5) mmHg in sequential analysis, and -1.3 (2.2) mmHg and -1.9 (2.7) mmHg in simultaneous analysis. CONCLUSION: The Maxi Stabil aneroid device can be recommended for use in an adult population.
Adult↗
Antimicrobials in the prevention of prematurity.
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Anti-Infective Agents↗
Ultrasound-indicated cervical cerclage: outcome depends on preoperative cervical length and presence of visible membranes at time of cerclage.
OBJECTIVE: The purpose of this study was to assess cases of ultrasound-indicated cervical cerclage and to relate preoperative cervical length, operative findings, postoperative cervical length, and pregnancy outcome to establish the appropriate criteria to offer cervical cerclage. STUDY DESIGN: A prospective observational study comprised 380 women at high risk of preterm labor who underwent serial transvaginal ultrasonographic assessment of cervical length. Seventy-three women had criteria for and underwent cervical cerclage. Data concerning preoperative cervical length, operative findings, postoperative cervical length, and pregnancy outcome were collected. Statistical analysis was performed with Mann-Whitney and Fisher exact tests. RESULTS: There was a significant increase in median cervical length after cerclage, 15.0 versus 25.0 mm (P <.0001). Preoperative cervical length and postoperative upper cervical length were independently better predictors of outcome than postoperative entire cervical length. Fetal membranes were visible in 18% of cases at the time of suture insertion, which was associated with a significantly worse outcome, regardless of preoperative cervical length. Of those 41 women with a very short preoperative cervical length (< or = 15 mm), outcome was significantly worse in those women with visible fetal membranes at the time of cerclage compared with those women with no visible fetal membranes at the time of cerclage: median gestational age at delivery, 23 weeks versus 37 weeks 4 days (P =.002); suture insertion to delivery interval, 19 days versus 108 days (P =.0004); and fetal survival rates, 50% versus 86% (P =.03). CONCLUSION: In a high-risk population that undergoes serial transvaginal ultrasound surveillance of cervical length, the presence of visible fetal membranes at the time of suture insertion, regardless of preoperative cervical length, is associated with a poor outcome. Fetal membranes were not visible in any cases with a preoperative cervical length of >15 mm. These findings lend support to a practice of offering cerclage at or above a cervical length of 15 mm.
Adult↗
Hidden errors of aneroid sphygmomanometers.
BACKGROUND: Measurement of blood pressure remains the most commonly performed screening test in medical practice. With the likely removal of mercury sphygmomanometers from the workplace alternative devices are required. Of these the aneroid sphygmomanometer is popular both in the community and hospital setting. We investigated the accuracy of all the aneroid and mercury sphygmomanometers during dynamic calibration within a tertiary referral maternity hospital. METHODS: We compared the accuracy of 39 aneroid and 36 mercury sphygmomanometers to a recently calibrated and serviced mercury sphygmomanometer (the accepted gold standard). All devices were in current clinical use. Using three blinded, trained observers, 30 different pressures were checked throughout the pressure range following British Hypertension Society protocol guidelines. RESULTS: Only 31 (86%) of the mercury devices and 36 (92%) of the aneroid devices were in adequate working condition and suitable for analysis. Significantly more aneroid devices had systematic errors of > 5 mmHg (19 versus 3%, < 0.05). Fifty percent of aneroid devices had at least one reading > 10 mmHg out compared to only 10% of mercury devices (chi square programme). CONCLUSIONS: Aneroid sphygmomanometers in apparent good working order are inaccurate compared to mercury devices. Some of these faults can only be detected during dynamic testing. To minimize the risk of erroneous blood pressure recording, aneroid devices should be regularly checked for accuracy using dynamic calibration methods as recommended in validation protocols.
Adult↗
Validation of the Microlife BP 3BTO-A oscillometric blood pressure monitoring device according to a modified British Hypertension Society protocol.
BACKGROUND: The market for devices for the self-measurement of blood pressure is growing, and as accuracy is of prime importance, there is increasing pressure for manufacturers to provide evidence of independent testing. Recent reviews have shown that only five automated upper arm devices for self-measurement of blood pressure have been recommended for use. We tested the Microlife BP 3BTO-A, a lightweight, upper arm, automated oscillometric device, according to a modified version of the British Hypertension Society protocol and also analysed the computer-generated oscillograms for possible causes of inaccuracy. METHODS: One hundred and twenty-six subjects were recruited from general medical and specialist clinics and from amongst the staff at Guy's and St Thomas' Hospital, London, UK. Only 85 of these were included in the final analysis. Nine sequential readings were taken by two trained observers alternating between the mercury sphygmomanometer and the device. The last seven readings were analysed according to the British Hypertension Society protocol. Modifications to the protocol were: (1) the exclusion of patients whose blood pressure varied by more than 15 mmHg between sequential observer readings and (2) limited testing in the low systolic pressure range. RESULTS: The Microlife achieved a grade A for both systolic and diastolic pressure according to the British Hypertension Society protocol. The mean differences (standard deviation) between the observers and the device were -1.6 (7.7) mmHg and -2.1 (6.3) mmHg for systolic and diastolic blood pressure, respectively, therefore also fulfilling the criteria set by the Association for the Advancement of Medical Instrumentation. Sub-analysis for different pressure ranges showed that the device was less accurate in the high-pressure range (>160/100 mmHg). CONCLUSION: The Microlife can be recommended for clinical use in an adult population.
Adult↗
Inflationary oscillometric blood pressure monitoring: validation of the OMRON-MIT.
BACKGROUND: To evaluate the accuracy of the OMRON-MIT, (an automated inflationary oscillometric blood pressure monitoring device) for use in the general population by direct comparison to standard auscultatory mercury sphygmomanometry. DESIGN: Two trained, blinded observers taking simultaneous blood pressure measurements alternating between a mercury sphygmomanometer and the OMRON-MIT. METHODS: The evaluation was carried out according to the revised British Hypertension Society protocol. The validation data was also classified by the American Association for the Advancement of Medical Instrumentation (AAMI). RESULTS: The OMRON-MIT device achieved a BHS grade A for both systolic blood pressure (SBP) and diastolic blood pressure (DBP). It also met the criteria for the AAMI protocol, the mean difference between the MIT and standard was -2.0 +/- 7 mmHg for SBP and -2.0 +/- 6 mmHg for DBP. CONCLUSIONS: Inflationary oscillometry is a valid technique for the measurement of blood pressure. The OMRON-MIT, which uses this technique, is accurate and can be recommended for clinical use in the adult population.
Adult↗
Inflationary oscillometry provides accurate measurement of blood pressure in pre-eclampsia.
OBJECTIVE: To evaluate the accuracy of the OMRON-MIT inflationary oscillometric device for blood pressure measurement in pregnancy and pre-eclampsia. DESIGN: Prospective observational study, using validation methods recommended by the British Hypertension Society (BHS) and the Association for the Advancement of Medical Instrumentation (AAMI). SETTINGS: Antenatal clinics and ward, Guy's Hospital, London. POPULATION: Normotensive pregnant women and those diagnosed with pre-eclampsia according to the definition of the International Society for the Study of Hypertension in Pregnancy. METHODS: Validation according to BHS protocol. MAIN OUTCOME MEASURES: Proportion of readings within 5, 10 and 15 mmHg (absolute differences) between the automated device and two trained, blinded observers, according to the BHS and AAMI criteria. RESULTS: The OMRON-MIT achieved an overall BHS grade B for systolic and grade A for diastolic blood pressure measurement in both pregnancy and pre-eclampsia. The mean (SD) differences between the standard and the test device were -5 (7) mmHg for systolic and 2 (6) mmHg for diastolic blood pressure in pregnancy and -4 (6) mmHg for systolic and 2 (7) mmHg for diastolic blood pressure in pre-eclampsia. This device therefore fulfils the AAMI criteria. CONCLUSION: The OMRON-MIT is the only automated oscillometric device that has proven to be accurate for blood pressure measurement in pre-eclampsia according to the BHS protocol in pregnancy. Inflationary oscillometry may correct the error associated with oscillometric devices in pre-eclampsia.
Adolescent↗