Dysfibrinogenemia: discrepant results following infusion of purified fibrinogen.

Inherited dysfibrinogenemias are molecular disorders of fibrinogen that affect fibrin polymerization. The majority of cases are asymptomatic, but a significant proportion suffer from increased bleeding or thrombosis. We present two unrelated cases of dysfibrinogenemia, both of whom showed a characteristic discrepancy between fibrinogen activity and the immunologic fibrinogen. In one patient, the dysfibrinogenemia was confirmed by molecular analysis; in the other case, the diagnosis was presumptive based upon laboratory studies. Both patients underwent elective surgery. Both received a highly purified fibrinogen concentrate preoperatively and demonstrated a suboptimal laboratory response to the infusion. Three methods for determining fibrinogen concentration (Clauss fibrinogen, prothrombin-derived fibrinogen, and the viscoelastic functional fibrinogen) were utilized in the case of one patient, and these techniques showed discrepant results with the classic Clauss method giving the lowest concentration. Neither patient experienced excessive bleeding during surgery. Although these discrepancies have been previously described in untreated patients, their manifestation after infusion of purified fibrinogen is less well appreciated.

Postpartum Headache-Unmasking the Zebra Among the Horses: A Case Report.

Postdural puncture headache (PDPH) is a complication of dural puncture. An epidural blood patch (EBP) is the standard treatment; however, when EBP fails, alternative treatments and/or diagnoses must be considered. We present a case of orthostatic headache initially diagnosed as PDPH but likely due to spontaneous intracranial hypotension. It is imperative for anesthesiologists, as members of an interdisciplinary peripartum team, to be familiar with the evaluation and treatment of postpartum headache and recognize when further workup and consultation may be indicated.

Local anesthetic resistance in a Crohn's patient undergoing cesarean delivery.

INTRODUCTION: Patient resistance to local anesthetics is rarely considered as the cause of regional anesthesia failure. CASE REPORT: We report a case of resistance to local anesthetics in a patient with Crohn's disease who underwent cesarean section under continuous spinal anesthesia. DISCUSSION: Resistance to local anesthetics may be more common than we think, especially among patients with chronic pain. Providers should consider local anesthetic resistance when regional anesthesia is unsuccessful. Further research is needed to determine if skin wheal tests and/or a different local anesthetic could improve results.

Photoplethysmography and Heart Rate Variability for the Diagnosis of Preeclampsia.

BACKGROUND: The goal of this study was to determine a set of timing, shape, and statistical features available through noninvasive monitoring of maternal electrocardiogram and photoplethysmography that identifies preeclamptic patients. METHODS: Pregnant women admitted to Labor and Delivery were monitored with pulse oximetry and electrocardiogram for 30 minutes. Photoplethysmogram features and heart rate variability were extracted from each data set and applied to a sequential feature selection algorithm to discriminate women with preeclampsia with severe features, from normotensive and hypertensive controls. The classification boundary was chosen to minimize the expected misclassification cost. The prior probabilities of the misclassification costs were assumed to be equal. RESULTS: Thirty-seven patients with clinically diagnosed preeclampsia with severe features were compared with 43 normotensive controls; all were in early labor or beginning induction. Six variables were used in the final model. The area under the receiver operating characteristic curve was 0.907 (standard error [SE] = 0.004) (sensitivity 78.2% [SE = 0.3%], specificity 89.9% [SE = 0.1%]) with a positive predictive value of 0.883 (SE = 0.001). Twenty-eight subjects with chronic or gestational hypertension were compared with the same preeclampsia group, generating a model with 5 features with an area under the curve of 0.795 (SE = 0.007; sensitivity 79.0% [SE = 0.2%], specificity 68.7% [SE = 0.4%]), and a positive predictive value of 0.799 (SE = 0.002). CONCLUSIONS: Vascular parameters, as assessed noninvasively by photoplethysmography and heart rate variability, may have a role in screening women suspected of having preeclampsia, particularly in areas with limited resources.

Monitoring Fetal Heart Rate during Labor: A Comparison of Three Methods.

The purpose of the study was to compare the accuracy of a noninvasive fetal heart rate monitor with that of ultrasound, using a fetal scalp electrode as the gold standard, in laboring women of varying body habitus, throughout labor and delivery. Laboring women requiring fetal scalp electrode were monitored simultaneously with the investigational device (noninvasive fetal ECG), ultrasound, and fetal scalp electrode. An algorithm extracted the fetal heart rate from the noninvasive fetal ECG signal. Each noninvasive device recording was compared with fetal scalp electrode with regard to reliability by positive percent agreement and accuracy by root mean squared error. Seventy-one women were included in this analysis. Positive percent agreement was 83.4 ± 15.4% for noninvasive fetal ECG and 62.4 ± 26.7% for ultrasound. The root mean squared error compared with fetal scalp electrode-derived fetal heart rate was 4.8 ± 2.0 bpm for noninvasive fetal ECG and 14.3 ± 8.2 bpm for ultrasound. The superiority of noninvasive fetal ECG was maintained for stages 1 and 2 of labor and increases in body mass index. Compared with fetal scalp electrode-derived fetal heart rate, noninvasive fetal ECG is more accurate and reliable than ultrasound for intrapartum monitoring for stages 1 and 2 of labor and is less affected by increasing maternal body mass index. This confirms the results of other workers in this field.

Monitoring Uterine Activity during Labor: Clinician Interpretation of Electrohysterography versus Intrauterine Pressure Catheter and Tocodynamometry.

Objective The aim of this article was to compare clinical interpretation of uterine activity tracings acquired by tocodynamometry and electrohysterography with the gold standard, intrauterine pressure. Study Design Using data from a previous study, subjects who had simultaneous monitoring with all three uterine activity devices were included in this study. These were parturients who required intrauterine pressure catheter (IUPC) placement for obstetric indication. A Web-based application displayed scrolling 30-minute segments of uterine activity. Two blinded obstetricians and two blinded obstetric nurses independently reviewed the segments, marking uninterpretable segments and the peak of each contraction. Interpretability was compared using positive percent agreement. False positives are contractions marked in the noninvasive strip that have no corresponding contraction in the IUPC strip. False negatives are the reverse. Results A total of 135 segments, acquired during either Stage 1 (active labor) or Stage 2 (pushing), from 105 women, were included in this analysis. For all four observers, both interpretability and sensitivity of electrohysterography exceeded that of tocodynamometry (p < 0.0001). This remained true for the obese population (96 segments). Conclusion Compared with the IUPC, electrohysterography is more sensitive and provides tracings that are more often interpretable than tocodynamometry for intrapartum monitoring; electrohysterography is also less affected by increasing maternal body mass index.

Monitoring uterine activity during labor: a comparison of 3 methods.

OBJECTIVE: Tocodynamometry (Toco; strain gauge technology) provides contraction frequency and approximate duration of labor contractions but suffers frequent signal dropout, necessitating repositioning by a nurse, and may fail in obese patients. The alternative invasive intrauterine pressure catheter (IUPC) is more reliable and adds contraction pressure information but requires ruptured membranes and introduces small risks of infection and abruption. Electrohysterography (EHG) reports the electrical activity of the uterus through electrodes placed on the maternal abdomen. This study compared all 3 methods of contraction detection simultaneously in laboring women. STUDY DESIGN: Upon consent, laboring women were monitored simultaneously with Toco, EHG, and IUPC. Contraction curves were generated in real-time for the EHG, and all 3 curves were stored electronically. A contraction detection algorithm was used to compare frequency and timing between methods. Seventy-three subjects were enrolled in the study; 14 were excluded due to hardware failure of 1 or more of the devices (n = 12) or inadequate data collection duration (n = 2). RESULTS: In comparison with the gold-standard IUPC, EHG performed significantly better than Toco with regard to the Contractions Consistency Index (CCI). The mean CCI for EHG was 0.88 ± 0.17 compared with 0.69 ± 0.27 for Toco (P < .0001). In contrast to Toco, EHG was not significantly affected by obesity. CONCLUSION: Toco does not correlate well with the gold-standard IUPC and fails more frequently in obese patients. EHG provides a reliable noninvasive alternative, regardless of body habitus.

Peripartum acute coronary syndrome in an otherwise healthy patient.

Myocardial ischemia in pregnancy poses a significant challenge for the anesthesiologist. It is a relatively rare disorder (approximately 180 cases published in the indexed literature since 1922) but it carries high mortality. Diagnosis is frequently hampered by diminished sensitivity of several testing modalities conventionally used to diagnose myocardial ischemia. The etiology of cardiac ischemia also is multifactorial and occurs during a very dynamic period. A case of acute coronary syndrome in a parturient during urgent cesarean delivery for placental abruption is presented, followed by a brief review of the topic.

Virtual humans versus standardized patients: which lead residents to more correct diagnoses?

PURPOSE: Medical educators frequently use standardized patient (SP) encounters to bridge the gap between didactic education and practical application. Typically, SPs are healthy adults with no consistent physical findings; however, highly immersive virtual humans (VHs) may enable the consistent presentation of abnormal physical findings to multiple learners across multiple repetitions. Thus, the authors conducted this study to compare how frequently junior anesthesiology residents suspected obstructive sleep apnea (OSA) in preoperative assessments of SPs versus a VH. METHOD: The authors presented a patient whose case included the historical features of OSA (snoring, daytime fatigue, observed apnea, hypertension, and obesity). Three SPs (in 2008) and one VH (in 2009) were necessary to run the residents through the assessment. The VH appeared morbidly obese and had a neck circumference of 40 cm [corrected]. An airway exam of the VH displayed an image of redundant soft tissue, prominent tongue, and tonsillar hypertrophy. The VH responded to natural speech by recognizing "triggers" in a human's voice. The 849 triggers and 259 VH responses were designed with a technique that collects information from user interactions. RESULTS: Five of 21 residents (23.8%) suspected OSA after interviewing the SPs, whereas 11 of 13 residents (84.6%) suspected OSA after interviewing the VH (odds ratio of 17.6; 95% CI of 2.9-107). CONCLUSIONS: Residents suspected OSA much more frequently after interviewing the VH than after interviewing the SPs. The VH provides a unique opportunity to display numerous abnormal physical findings as part of SP encounters.

The Value of Anesthesiology in Undergraduate Medical Education as Assessed by Medical School Faculty.

BACKGROUND: Unlike Europe and Canada, the majority of American medical schools do not require an anesthesiology rotation. Yet the skill set and knowledge base of anesthesiologists includes many topics of importance to all physicians. Furthermore, the clinical environment offers more procedural experience and real-time physiology and pharmacology for teaching than that available elsewhere. Medical schools, however, often focus on "general medical education" and discount the value of a required anesthesiology clerkship. This begs the question, of the topics anesthesiologists excel at teaching, which are considered important by faculty across the spectrum of medical specialties? METHODS: Two-hundred-three senior medical students rated the importance to their career of 14 topics currently taught by lecture, simulation or reading assignment in the required anesthesiology curriculum at the University of Florida. Specialty faculty in each of the major specialties similarly rated the topics. The authors compared these with the opinion of 20 anesthesiology faculty who rated the importance of each topic for each major specialty. RESULTS: Overall, acute pain management and acute decompensation management were rated "somewhat" or "very important" by the highest proportion of respondents; followed closely by vascular access and fluid management, non-invasive monitoring and conscious sedation. The topics of interest to surgeons most closely aligned with those offered (12/14 rated somewhat or very important by >75% of faculty polled, 14/14: students), followed by emergency medicine physicians (10/14: faculty, 11/14: students). Significant differences of opinion existed between all three groups on several topics. CONCLUSIONS: Anesthesiologists excel in topics important to all future physicians; as many schools enter a new phase of curricular redesign, a rotation in anesthesiology should receive serious consideration. The input of students and physicians in major medical specialties may help define an appropriate curriculum. Including the flexibility for students to adapt that curriculum to individual goals may increase the rotation's value.

Spatiotemporal electrohysterography patterns in normal and arrested labor.

OBJECTIVE: The purpose of this study was to investigate the spatiotemporal patterns of uterine electrical activity in normal and arrested labors. STUDY DESIGN: From a database of electrohysterograms, 12 subjects who underwent cesarean delivery for active-phase arrest were each matched with 2 vaginally delivered controls. Using 30-minute segments of the electrohysterogram during the arrest, or the same dilation in controls, the center of uterine electrical activity was derived. The vertical motion of this center of uterine activity was determined for each contraction and the frequencies of movement patterns analyzed. RESULTS: Predominantly upward movement of the center of uterine activity (longer and/or stronger contraction at the fundus) was more common with normal dilation (P = .003). Receiver operating characteristic curve analysis gave an area under the curve of 0.91 for predicting outcome (vaginal vs cesarean delivery). CONCLUSION: There is a significant correlation between upward movement of the center of uterine activity (fundal dominance) and current labor progress.

Monitoring contractions in obese parturients: electrohysterography compared with traditional monitoring.

OBJECTIVE: To compare electrohysterogram-derived contractions with both tocodynamometry and intrauterine pressure monitoring in obese laboring women. METHODS: From a large database of laboring patients with electrohysterogram monitoring, obese subjects were selected in whom data were recorded for at least 30 minutes before and after intrauterine pressure catheter placement for obstetric indication. Using a contraction detection algorithm, the relationship between the methods was determined with regard to both frequency and contraction duration. RESULTS: Of the 25 subjects (median body mass index 39.6 [25th percentile 36.5, 75th percentile 46.3]), seven underwent amniotomy at the time of intrauterine pressure catheter placement. Tocodynamometry identified 248 contractions compared with 336 by electrohysterography, whereas intrauterine pressure catheter monitoring identified 319 contractions compared with 342 by electrohysterography. Using the Contractions Consistency Index, electrohysterogram contraction detection correlated better with the intrauterine pressure catheter (0.94+/-0.06) than with tocodynamometry (0.77+/-0.25), P=.004. Electrohysterogram-derived contraction lengths closely approximated those calculated from the intrauterine pressure catheter signal. CONCLUSION: Contraction monitoring routinely is employed for managing labor, and tocodynamometry may be unreliable in obese parturients. In the obese women in this study, the electrohysterogram-derived contraction pattern correlated better with the intrauterine pressure catheter than tocodynamometry. Electrohysterography may provide another noninvasive means of monitoring labor, particularly for those women in whom tocodynamometry is inadequate.

Prediction of intrauterine pressure waveform from transabdominal electrohysterography.

OBJECTIVE: We investigated the ability to non-invasively obtain uterine electromyograms (EMG; electrohysterogram (EHG)) to predict the intrauterine pressure (IUP) waveform. STUDY DESIGN: Patients enrolled in a term labor study of trans-abdominal electrical activity, who underwent IUP monitoring for obstetric indication, were included in this study (n=14). EHG signals were processed and prediction filters trained against the IUP from the same patient. Sixty-eight 10-minute traces each of EHG and IUP waveforms were reviewed (Montevideo unit (MVU) calculation) by two experienced labor nurses and one obstetrician, blinded to patient and EHG vs. IUP output. In addition, area under the contraction curve (AUC), contraction detection and duration were compared. RESULTS: EHG-derived MVUs statistically correlated with IUP (r=0.795; p < 0.0001), but mathematically differed by 17+/-20% with 83% of EHG MVUs underestimating the IUP. The coefficients of variation between the two methods were relatively high ( approximately 20%), and these could not be substantially corrected via calibration. AUC differed by 8+/-19% with 69% of EHG-derived AUC underestimating the IUP. EHG detected 98% of 362 IUP contractions, with 8% over-detection. Contraction duration was similar: 56.4+/-11.9 s vs. 55.7+/-13.0 s, for IUP and EHG, respectively. CONCLUSION: EHG-based contraction monitoring approximates IUP monitoring for contraction detection and duration. The correlation with contraction height (MVU) and AUC is much weaker with the investigated signal-processing algorithm.

Prediction of intrauterine pressure from electrohysterography using optimal linear filtering.

We propose a method of predicting intrauterine pressure (IUP) from external electrohysterograms (EHG) using a causal FIR Wiener filter. IUP and 8-channel EHG data were collected simultaneously from 14 laboring patients at term, and prediction models were trained and tested using 10-min windows for each patient and channel. RMS prediction error varied between 5-14 mmHg across all patients. We performed a 4-way analysis of variance on the RMS error, which varied across patients, channels, time (test window) and model (train window). The patient-channel interaction was the most significant factor while channel alone was not significant, indicating that different channels produced significantly different RMS errors depending on the patient. The channel-time factor was significant due to single-channel bursty noise, while time was a significant factor due to multichannel bursty noise. The time-model interaction was not significant, supporting the assumption that the random process generating the IUP and EHG signals was stationary. The results demonstrate the capabilities of optimal linear filter in predicting IUP from external EHG and offer insight into the factors that affect prediction error of IUP from multichannel EHG recordings.

A single dose of fentanyl and midazolam prior to Cesarean section have no adverse neonatal effects.

PURPOSE: Analgesia and sedation, routinely used as adjunct medications for regional anesthesia, are rarely used in the pregnant patient because of concerns about adverse neonatal effects. In an effort to obtain more information about maternal analgesia and sedation we studied neonatal and maternal effects of iv fentanyl and midazolam prior to spinal anesthesia for elective Cesarean section. METHODS: In this double-blinded, randomized, placebo-controlled trial, 60 healthy women received either a combination of 1 microg x kg(-1) fentanyl and 0.02 mg x kg(-1) midazolam intravenously or an equal volume of iv saline at the time of their skin preparation for a bupivacaine spinal anesthetic. Sample size was based on a non-parametric power analysis (power > 0.80 and alpha = 0.05) for clinically important differences in Apgar scores. Fetal outcome measures included Apgar scores, continuous pulse oximetry for three hours, and neurobehavioural scores. Maternal outcomes included catecholamine levels, and recall of anesthesia and delivery. RESULTS: There were no between-group differences of neonatal outcome variables (Apgar score, neurobehavioural scores, continuous oxygen saturation). Mothers in both groups showed no difference in their ability to recall the birth of their babies. CONCLUSIONS: Maternal analgesia and sedation with fentanyl (1 microg x kg(-1)) and midazolam (0.02 mg x kg(-1)) immediately prior to spinal anesthesia is not associated with adverse neonatal effects.

Development and Evaluation of an Internet-Based Airway Evaluation Tutorial.

Airway evaluation and basic management are essential skills for all physicians. Identifying patients for whom mask ventilation or endotracheal intubation will be difficult to impossible is vital for patient safety. Despite this, training in airway evaluation is minimal in the curricula of most medical schools. To ensure a thorough understanding of airway anatomy and evaluation, as well as exposure to various abnormal findings, we developed an Internet-based module including interactive components, graphics, animation, video, and a self-assessment tool. The site received more than 1800 visits in its first nine months of operation, with uniformly laudatory comments. Eighty subjects over a six-month period completed a pre- and post-test quiz structured to evaluate the utility of the site. Of those completing the on-line survey, more than 76% rated the site very useful. Most felt their knowledge of airway examination improved after completion of the site (p.

Anesthesia for childbirth: controversy and change.

First introduced to medical practice in 1847, anesthesia for childbirth has undergone constant changes. Current practice reflects evolving social values as well as new discoveries in science and medicine.

Vaginal birth after cesarean delivery: an historic cohort cost analysis.

OBJECTIVE: The purpose of this study was to evaluate the relative cost-effectiveness of attempted vaginal birth after cesarean delivery compared with elective repeat cesarean delivery. STUDY DESIGN: We performed an historic cohort analysis of women with a single prior cesarean delivery who were delivered at our institution during 1999. Inclusion criteria were > or =36 weeks' gestation and carrying a live, singleton fetus with no antenatally diagnosed anomalies. The primary outcome variable was mean cost of hospital care for mother-infant pairs, as obtained from the hospital's Clinical Resources Department. RESULTS: The cohort consisted of 204 mother-infant pairs, 65 in the elective repeat cesarean group and 139 in the attempted vaginal birth group. Mean cost of care was higher for mothers ($4155 vs $3675;P <.001), neonates ($1794 vs $1187; P =.03), and mother-infant pairs ($5949 vs $4863; P =.001) for the elective repeat cesarean group compared with the attempted vaginal delivery group. CONCLUSION: In women with a single prior cesarean delivery, a trial of labor is more cost-effective than an elective repeat cesarean delivery.