Severe perineal laceration during operative vaginal delivery: the impact of occiput posterior position.

OBJECTIVE: To identify risk factors for severe (third/fourth degree) perineal laceration with operative vaginal delivery (OVD, forceps or vacuum). STUDY DESIGN: Case-control study comparing singleton OVDs with or without severe laceration (n=138). RESULT: In multivariable analyses, severe perineal laceration was associated with occiput posterior (OP) position at delivery, vaginal nulliparity, use of forceps, longer period pushing in the second stage and lower gestational age, but not birth weight, labor induction or episiotomy. Among 29 OP patients at full dilation, 9/13 (69%) attempted rotations to occiput anterior (OA) were successful, and 14/16 (88%) patients in whom rotation was not attempted remained OP at delivery. Successful rotation from OP to OA was associated with fewer severe lacerations than no attempt or unsuccessful rotation (22 vs 75%, P=0.01). CONCLUSION: Severe perineal laceration during OVD is associated with OP position at delivery and is reduced threefold in patients successfully rotated from OP to OA.

Dose response to intrathecal diamorphine for elective caesarean section and compliance with a national audit standard.

BACKGROUND: This double-blind randomised controlled trial investigated the most appropriate dose of intrathecal diamorphine to use with high-dose diclofenac as part of a multimodal analgesic regimen for caesarean section under subarachnoid block. We also wished to establish whether it was possible to satisfy the Royal College of Anaesthetists postoperative pain audit recommendation for this patient group. METHODS: One hundred and twenty patients presenting for elective caesarean section under subarachnoid block were recruited and divided into four groups. Treatment was standard except that patients were given either placebo or one of three different doses of intrathecal diamorphine (100 microg, 200 microg or 300 microg). All patients were given regular paracetamol, high-dose diclofenac and an hourly subcutaneous diamorphine regimen for breakthrough pain. RESULTS: There was a dose-dependent improvement in analgesia with intrathecal diamorphine. Only 37.9% of patients given 300 microg of intrathecal diamorphine had a visual analogue pain score of 3/10 or less throughout the study. There was a dose-dependent increase in the incidence of itching with intrathecal diamorphine although the incidence of nausea and vomiting was similar between groups. CONCLUSIONS: We found that for elective caesarean section under subarachnoid block with high dose diclofenac, analgesia was optimal with 300 microg of intrathecal diamorphine. Even the highest dose of intrathecal diamorphine did not achieve the Royal College of Anaesthetists postoperative audit target that 90% of patients should have a pain score of no more than 3/10. We believe that this target is too arduous.

Postpartum hemorrhage in resource-poor settings.

Despite the strong interest of international health agencies, worldwide maternal mortality has not declined substantially over the past 10 years. Postpartum hemorrhage (PPH) is the most common cause of maternal death across the world, responsible for more than 25% of deaths annually. Although effective tools for prevention and treatment of PPH are available, most are not feasible or practical for use in the developing world where many births still occur at home with untrained birth attendants. Application of many available clinical solutions in rural areas would necessitate substantial changes in government infrastructure and in local culture and customs surrounding pregnancy and childbirth. Before treatment can be administered, prompt and accurate diagnosis must be made, which requires training and appropriate blood measurement tools. After diagnosis, appropriate interventions that can be applied in remote settings are needed. Many uterotonics known to be effective in reducing PPH in tertiary care settings may not be useful in community settings because they require refrigeration and/or skilled administration. Moreover, rapid transfer to a higher level of care must be available, a challenge in many settings because of distance and lack of transportation. In light of these barriers, low-technological replacements for treatments commonly applied in the developed-world must be utilized. Community education, improvements to emergency care systems, training for birth attendants, misoprostol, and Uniject have shown promise as potential solutions. In the short term, it is expedient to capitalize on practical opportunities that utilize the existing strengths and resources in each community or region in order to implement appropriate solutions to save the lives of women during childbirth.

Frequency, characteristics, and clinical significance of transient ST segment elevation in patients with acute coronary syndromes.

BACKGROUND: Prior investigations of transient myocardial ischaemia have focused on ST depression events. Therefore, the purpose of this analysis was to determine the frequency, characteristics, and clinical significance of transient ST segment elevation in patients with acute coronary syndromes. METHODS: A secondary analysis from two prospective studies utilizing 12-lead ST segment monitoring was used to compare ST elevation vs ST depression events. RESULTS: Of 868 patients, 177 (20%) had 574 events (242, ST elevation; 332, ST depression). Patients with ST elevation were more likely to have single vessel coronary artery disease, whereas patients with ST depression were more likely to have triple vessel coronary artery disease. ST elevation events were of shorter duration, more often associated with chest pain, and had greater ST changes than ST depression events. There was no difference in clinical outcome between patients with ST elevation vs depression; however, those with ST events were more likely to have adverse hospital outcomes (OR, 3.67) or death (OR, 2.03) than patients without ST events. After controlling for clinical prognostic factors, transient ST events observed with continuous ST monitoring predicted hospital death independently from signs of ischaemia on the initial standard 12-lead ECG. CONCLUSIONS: Transient ST elevation is nearly as prevalent as transient ST depression in patients with acute coronary syndromes. Since the vast majority of ST events are brief and otherwise clinically silent, ST segment monitoring is more efficacious in detecting ischaemic events and in predicting adverse clinical outcomes than patients' symptoms or the initial standard 12-lead ECG.

Spontaneous intracranial hypotension--lessons to be learned for the investigation of post dural puncture headache.

We describe a case of spontaneous intracranial hypotension in a 36-year-old woman. This condition shares many of the features of post dural puncture headache, but without a dural puncture having been performed. The aetiology and management of this rare condition are discussed. We believe from experience within our own unit that most anaesthetists are unaware of spontaneous intracranial hypotension. Highlighting this condition is important, as anaesthetists are often involved in its management. In our case, radiological investigation involved the use of spiral computerised tomography to identify the site of the hole in the dura. Spiral computerised tomography is a relatively recent innovation, which may also be useful in the investigation of post dural puncture headache when the level of the puncture is unknown.

Clinical consequences of ST-segment changes caused by body position mimicking transient myocardial ischemia: hazards of ST-segment monitoring?

A case is described in which an acute ST-segment change, presumably due to a change in body position, is erroneously interpreted as an acute ischemic event. Positional ST-segment changes during continuous, multi-lead electrocardiographic (ECG) monitoring are particularly challenging to distinguish from transient myocardial ischemia because 1) positional ECG templates are often not feasible to record at the beginning of monitoring in unstable patients; 2) positional ECG templates, if recorded, are often not readily accessible to clinicians for later comparison; 3) body position cannot be correlated with ST events because patients are out of the direct view of nurses during the event or clinicians review ST trends at a later time; 4) ST monitors typically do not store ECGs frequently enough to be able to observe on the ST trend the gradual ("ramp-like") onset of ST changes that is characteristic of transient ischemia; and 5) absence of chest pain with a ST event does not help clinicians identify false alarms because it is well understood that the majority of ischemic events are clinically silent.

Frequency of silent myocardial ischemia with 12-lead ST segment monitoring in the coronary care unit: are there sex-related differences?

BACKGROUND: Ischemia that occurs in the coronary care unit (CCU), whether symptomatic or silent, is associated with significant in-hospital and out-of-hospital complications. Studies have reported that more than 90% of ischemic episodes are silent in patients with unstable angina who are treated in the CCU with maximal medical therapy. Prior reports indicate that women complained more frequently of chest pain than men did. PURPOSE: The aim of this study was to compare the frequency of silent myocardial ischemia in men versus women with use of continuous 12-lead ST segment monitoring in the CCU. A secondary goal was to determine whether silent ischemia was associated with less ST segment deviation as compared with symptomatic ischemia. METHOD: Patients admitted for treatment of acute coronary syndrome in the CCU and who subsequently had 1 or more ischemic events during their monitoring period were selected for this analysis. All patients were continuously monitored (42.5 hours +/- 37.6) in the CCU with the EASI (Zymed Medical Instruments, Camarillo, Calif) 12-lead electrocardiogram (ECG) system that derives 12 leads with use of 3 information channels and 5 electrodes. RESULTS: Of 491 patients, 128 (91 men and 37 women) had at least 1 episode of transient myocardial ischemia. Men and women did not differ in their proportion of chest pain during ischemia (men 27% and women 21%, NS). For both men and women, ST segment deviation was significantly greater during symptomatic ischemia compared with silent ischemia. CONCLUSION: There are no sex-related differences in ischemic events in the CCU in regards to the variables of chest pain and ST magnitude. Therefore, because chest pain is not a reliable indicator of myocardial ischemia in the CCU, regardless of sex, patients should be adequately monitored for ischemic events.

Accuracy of the EASI 12-lead electrocardiogram compared to the standard 12-lead electrocardiogram for diagnosing multiple cardiac abnormalities.

This study was performed to compare a derived 12-lead electrocardiogram (ECG) using a simple 5-electrode lead configuration (EASI 12-lead) with the standard ECG for multiple cardiac diagnoses. Accurate diagnosis of arrhythmias and ischemia often require analysis of multiple (ideally, 12) ECG leads; however, continuous 12-lead monitoring is impractical in hospital settings. EASI and standard ECGs were compared in 540 patients, 426 of whom also had continuous 12-lead ST segment monitoring with both lead methods. Independent standards relative to a correct diagnosis were used whenever possible, for example, echocardiographic data for chamber enlargement-hypertrophy, and troponin levels for acute infarction. Percent agreement between the 2 methods were: cardiac rhythm, 100%; chamber enlargement-hypertrophy, 84%-99%; right and left bundle branch block, 95% and 97%, respectively; left anterior and posterior fascicular block, 97% and 99%, respectively; prior anterior and inferior infarction, 95% and 92%, respectively. There was very little variation between the 2 lead methods in cardiac interval measurements; however, there was more variation in P, QRS, and T-wave axes. Of the 426 patients with ST monitoring, 138 patients had a total of 238 ST events (26, acute infarction; 62, angioplasty-induced ischemia; 150, spontaneous transient ischemia). There was 100% agreement between the 2 methods for acute infarction, 95% agreement for angioplasty-induced ischemia, and 89% agreement for transient ischemia. EASI and standard 12-lead ECGs are comparable for multiple cardiac diagnoses; however, serial ECG changes (eg, T-wave changes) should be assessed using one consistent 12-lead method.

Frequency of ischemia during intracoronary ultrasound in women with and without coronary artery disease.

Myocardial ischemia is common during ICUS imaging in women with and without CAD. Although no long-term adverse effects occurred in our small sample, a larger sample of women is required to confirm our observations and to determine the precise mechanisms of ischemia. Such studies may determine whether the smaller diameter of coronary vessels in women makes the women more vulnerable than men to the occurrence of chest pain and ischemia during ICUS. Although ICUS is valuable in guiding coronary interventions, disposable catheters are costly. Studies are required to assess the cost-benefit ratio of incorporating ICUS with coronary interventional procedures. Until more is known, we recommend that nurses educate patients about ICUS, monitor them closely for ischemia and arrhythmias during the procedure, and consider obtaining 12-lead ECGs when patients undergo and ICUS procedure.

Peak time of occurrence of myocardial ischemia in the coronary care unit.

BACKGROUND: The onset of acute myocardial infarction and sudden cardiac death has a circadian variation, with the peak occurrence between 6 AM and 12 noon. OBJECTIVES: To determine if a circadian variation exists for transient myocardial ischemia in patients admitted to the coronary care unit with unstable coronary syndromes. METHODS: The sample was selected from patients enrolled in a prospective clinical trial who had had ST-segment monitoring for at least 24 hours and had had at least one episode of transient ischemia. The 24-hour day was divided into 6-hour periods, and comparisons were made between the 4 periods. RESULTS: In 99 patients, 61 with acute myocardial infarction and 38 with unstable angina, a total of 264 (mean +/- SD, 3 +/- 2) ischemic events occurred. Patients were more likely to have ischemic events between 6 AM and noon than at other times. A greater proportion of patients complained of chest pain between 6 AM and noon than during the other 3 periods. However, more than half the patients never complained of chest pain during ischemia between 6 AM and noon. CONCLUSION: Transient ischemia occurs throughout the 24-hour day; however, ischemia occurs more often between 6 AM and noon. An important nursing intervention for detecting ischemia is continuous electrocardiographic monitoring of the ST segment, even during routine nursing care activities, which are often at a peak during the vulnerable morning hours.

12-lead ST-segment monitoring vs single-lead maximum ST-segment monitoring for detecting ongoing ischemia in patients with unstable coronary syndromes.

BACKGROUND: 12-lead ECG monitoring of the ST segment is more sensitive than patients' symptoms for detecting ischemia after thrombolytic therapy or catheter-based interventions, but it is unclear whether monitoring of the single lead showing maximum ST deviation would be as efficacious. OBJECTIVE: To determine whether monitoring all 12 ECG leads for changes in the ST segment is necessary to detect ongoing ischemia in patients with unstable coronary syndromes. METHODS: Continuous 12-lead ST segment monitoring was performed in 422 patients from the onset of myocardial infarction or during balloon inflation in catheter-based interventions until the patient's discharge from the cardiac care unit. Computer-assisted techniques were used to determine (1) which lead showed the maximum ST deviation at the onset of myocardial infarction or during balloon inflation and (2) what proportion of later ischemic events were associated with ST deviation in this lead. RESULTS: The lead with the maximum ST deviation could be determined in 312 patients (74%). The remaining 110 (26%) had non-Q wave infarction without ST deviation or no ST changes during balloon inflation. During 18,394 hours of 12-lead ST monitoring, 118 (28%) of the 312 patients had a total of 463 ischemic events, 80% of which were silent. Of 377 ischemic events in which a maximum ST lead was detected, 159 (42%) did not show ST deviation in this lead (sensitivity, 58%; 95% CI, 53%-63%). Routine monitoring of leads V1 and II showed ST deviation in only 152 of the 463 events (sensitivity, 33%; 95% CI, 29%-37%). CONCLUSIONS: Monitoring of all 12 ECG leads for changes in the ST segment is necessary to detect ongoing ischemia in patients with unstable coronary syndromes.

Bedside diagnosis of myocardial ischemia with ST-segment monitoring technology: measurement issues for real-time clinical decision making and trial designs.

Monitoring of the ST segment is a valuable tool for guiding clinical decision making and evaluating anti-ischemia interventions in clinical trials; however, measurement issues hamper its diagnostic accuracy. This study reports the frequency and type of false positives and other measurement issues we have encountered during 12-lead ST-segment monitoring of patients in a cardiac care unit. Of 292 patients, 117 (40%) had one or more false positive events during an average of 41 hours of ST-segment monitoring, for a total of 506 false positive events. The 506 false positive events included 167 (36%) due to body positional change; 132 (26%) due to sudden increase in QRS complex/ST-segment voltage; 96 (19%) due to transient arrhythmia or pacing; 80 (16%) due to heart rate change in steeply sloped ST-segment contours; 26 (5%) due to a noisy signal; and 5 (1%) due to lead misplacement. It is concluded that many conditions in addition to myocardial ischemia can cause transient ST-segment deviation in patients with unstable coronary syndromes. Accurate ST-segment monitoring requires expertise in electrocardiogram interpretation, an understanding of the patient's clinical situation, and knowledge of the functions and limitations of the ST-segment monitoring system.

Body position effects on the ECG: implication for ischemia monitoring.

Rotation of the heart in relation to surface electrocardiographic (ECG) electrodes when a patient turns to one side has been reported to cause ST-segment shifts, triggering false alarms with continuous ST-segment monitoring. We prospectively analyzed ST-segment and QRS complex changes in both standard and derived ECGs in 40 subjects (18 with heart disease and 22 healthy) in supine, right- and left-lying positions. Of the 40 subjects, 6 (4 cardiac, 2 healthy) developed positional ST deviations of 1 mm or more on the standard ECG. In the derived method, five of the same six subjects showed ST-segment deviation of which most occurred in the left-lying position. Positional ST changes were most frequent for males and for cardiac patients (33%). Changes in QRS complex morphology were common on the standard (28 of 40, 70%) and less frequent on the derived ECGs (17 of 40, 43%), occurring in both healthy and cardiac subjects. QRS axis changes occurred only on the standard ECG. It was concluded that (1) right and left side-lying positions frequently induce clinically significant ECG changes; (2) positional ST-segment deviation is less frequent than previously reported and is most likely to occur in males with cardiac disease; and (3) the derived method is less prone to positional QRS changes than the standard ECG.

Frequency, duration, magnitude, and consequences of myocardial ischemia during intracoronary ultrasonography.

To determine the frequency, duration, magnitude, and possible adverse effects of ischemia during intracoronary ultrasonography, real-time standard 12-lead electrocardiograms were recorded before, during, and after ultrasonography. Ischemia was defined as new-onset ST segment deviation of > or = 1 mm in one or more leads, measured at J + 80 msec. The magnitude of ischemia was expressed as the sum of absolute ST segment deviations across 12 leads. Eighteen (67%) of 27 patients had ischemia during intracoronary ultrasonography. The electrocardiogram resembled the characteristic pattern observed with occlusion of the vessel under study, involving ST segment elevation in contiguous leads in 89% of patients. A higher proportion of women (88%) had ischemia than men (58%), and women had smaller arterial lumenal areas compared with men (6.3 vs 9.1 mm2; p < 0.05). Individuals with ischemia were smaller than those without ischemia (body surface area = 1.99 vs 1.79 m2; p = 0.01). The mean duration of ischemia was 4 minutes and the mean 12-lead ST segment deviation score was 8.5 mm (maximum 20.5 mm). No patient with ischemia during ultrasonography had complications. Ischemia is common during intracoronary ultrasonography, particularly in women and individuals with smaller vessels; however, no adverse outcomes occur as a result.

Computer versus manual measurement of ST-segment deviation.

Total ST scores (sum of absolute deviations in all 12 electrocardiographic [ECG] leads) have been used for research purposes to estimate total ischemic burden and to predict reperfusion after thrombolytic therapy. Computerized monitoring systems are capable of measuring ST deviation to the 10-microV level, whereas humans are incapable of such precise resolution. The purpose of this study was to compare computer versus manual ST scores in 12-lead ECGs exhibiting ischemia and to compare interrater reliability of manual measurements between two experts. A total of 58 subjects with 100 microV or more ST deviation in one or more leads during percutaneous transluminal coronary angioplasty balloon inflation were selected for analysis. ST measurements were made at J + 80 ms, using the isoelectric line as a reference, and summed across all 12 leads. Manual measurements were made to a minimum of 50 microV by two independent reviewers blinded to the computer scores. Total ST scores were compared using paired t-tests, and Pearson coefficients were used to test the correlations. A high correlation was observed between the manual and computer measurements (r = .96, P < .00) and between the two reviewers (r = .96, P < .00). A high degree of interrater reliability is possible with manual measurements of ST deviation. Computer measurements are consistently greater than manual measurements, presumably because humans "round down" to the nearest 50 microV. As such, computers may detect ischemia that is missed by humans. However, computer and manual measurements of ST deviation should not be mixed when used as a variable for research.

Comparison of standard and derived 12-lead electrocardiograms for diagnosis of coronary angioplasty-induced myocardial ischemia.

To determine whether a derived 12-lead electrocardiogram (ECG) would demonstrate typical ST-segment changes of ischemia during percutaneous transluminal coronary angioplasty (PTCA), 207 patients were monitored with continuous 12-lead ST-segment monitoring during angioplasty. Additionally, to compare the derived and standard ECGs during known periods of ischemia with PTCA balloon inflation, 151 patients were recorded with both electrocardiographic methods during the procedure. Of the 207 patients recorded with the derived ECG, 171 (83%) had typical ischemic ST-segment changes during PTCA balloon inflation. The amplitudes of these ST deviations were similar to those observed during transient myocardial ischemia observed in clinical settings (median peak ST deviation, 225 microV). There was agreement regarding presence or absence of ischemia in 150 of the 151 patients recorded with both derived and standard electrocardiographic methods (> 99% agreement). With use of the standard ECG as the "gold standard" for ischemia diagnosis, there were no false-positive results and only 1 false-negative result with the derived ECG. Furthermore, there was nearly perfect agreement between the two 12-lead methods in terms of anterior versus inferior wall patterns of ischemia. Future studies are required to determine whether continuous monitoring with a derived ECG would improve diagnosis and lead to better patient outcomes.

ST segment monitoring with a derived 12-lead electrocardiogram is superior to routine cardiac care unit monitoring.

BACKGROUND: Prior studies have shown that a derived 12-lead electrocardiogram with a simple electrode configuration is comparable with the standard electrocardiogram for arrhythmia analysis. METHODS: A prospective, comparative, within subjects design was used to compare the value of the derived 12-lead electrocardiogram with that of routine monitoring of leads V1 and II for detection of transient myocardial ischemia in 250 patients treated for unstable angina or myocardial infarction. RESULTS: During 11,532 hours of derived 12-lead ST segment monitoring, 55 (22%) of 250 patients had 176 episodes of ischemia. Of the 55 patients with ischemia, 75% reported no chest pain and 64% had no ischemic ST changes with routine monitoring leads. All five patients who developed angiographically confirmed abrupt reocclusion after percutaneous transluminal coronary angioplasty had ischemic ST changes with the derived electrocardiogram (sensitivity, 100%), compared with only two patients with routine monitoring (sensitivity, 40%). Serious complications occurred in 17% of angina patients with ischemic events compared to 3% of those without ischemia. Length of stay in the cardiac care unit was twice as long in angina patients who had ischemic events. In patients with acute myocardial infarction, ischemic events were not associated with a more complicated hospital course; however, length of stay in the cardiac care unit was longer in patients with recurrent ischemia. CONCLUSIONS: The findings show that derived 12-lead ST monitoring is superior to routine monitoring of leads V1 and II for detecting transient myocardial ischemia. ST monitoring of the derived 12-lead electrocardiogram may identify high-risk patients with unstable angina and provide prognostic information that would not be otherwise available from the usual clinical measures.