Obstetric comorbidity index and the odds of general vs. neuraxial anesthesia in women undergoing cesarean delivery: a retrospective cohort study.

BACKGROUND: Maternal and fetal concerns have prompted a significant reduction in general anesthesia (GA) use for cesarean delivery (CD). The obstetric comorbidity index (OB-CMI) is a validated, dynamic composite score of comorbidities encountered in an obstetric patient. We sought to estimate the association between OB-CMI and odds of GA vs. neuraxial anesthesia (NA) use for CD. METHODS: In this single-center, retrospective cohort study conducted at a large academic hospital in the United States of America, OB-CMI was calculated on admission and every 12 h for women undergoing CD at ≥23 weeks' gestation (n=928). The CD urgency, anesthesia type, and most recent OB-CMI were extracted from the medical record. The association between OB-CMI and GA use was estimated by logistic regression, with and without adjustment for CD urgency, parity and race. RESULTS: Each one-point increase in OB-CMI was associated with a 32% (95% confidence interval [CI] 17% to 48%) increase in the odds of GA use (Model 1, area under the receiver operating characteristic curve [AUC] 0.708, 95% CI 0.610 to 0.805). The AUC improved to 0.876 (95% CI 0.815 to 0.937) with the addition of emergent CD (Model 2, P <0.001 vs. Model 1), but not parity and race (Model 3, AUC 0.880, 95% CI 0.824 to 0.935; P=0.616 vs. Model 2). CONCLUSIONS: The OB-CMI is associated with increased odds of GA vs. NA use for CD, particularly when emergent. Collected in real time, the OB-CMI may enable prophylaxis (e.g. comorbidity modification, earlier epidural catheter placement, elective CD) or preparation for GA use.

The venous system during pregnancy. Part 1: physiologic considerations.

An essential contributor to the hemodynamic responses observed during pregnancy, the venous system is affected by hormones, blood volume, flow rates, and an enlarging uterus. The venous system is a dynamic reservoir for blood volume, within which a virtual point of conversion between unstressed volume (Vu) and stressed volume (Vs) exists. The physiologic importance of the venous system during pregnancy is best understood when the basic concepts, functional characteristics, and alterations in pregnancy are reviewed.

The venous system during pregnancy. Part 2: clinical implications.

Maternal positioning, medications, and other modulations to the venous system can affect maternal and fetal well-being. The venous system is a dynamic reservoir for blood volume, in which a virtual point of conversion between unstressed volume (Vu) and stressed volume (Vs) exists. The anatomic and physiologic changes associated with hypotension (e.g. supine and neuraxial technique-induced), hypertension (e.g. preeclampsia), and fluid management (e.g. early recovery after cesarean delivery protocols) are opportunities to consider the important role of the venous system in pregnancy.

Intrathecal catheter use after accidental dural puncture in obstetric patients: literature review and clinical management recommendations.

If an accidental dural puncture occurs, one option is to insert a catheter and use it as an intrathecal catheter. This avoids the need for a further injection and can rapidly provide labour analgesia and anaesthesia for caesarean section. However, there are no recommendations for managing intrathecal catheters and, therefore, significant variation in clinical practice exists. Mismanagement of the intrathecal catheter can lead to increased motor block, high spinal anaesthesia, drug error, hypotension and fetal bradycardia. Care must be taken with an intrathecal catheter to adhere to strict aseptic technique, meticulous labelling, cautious administration of medications and good communication with the patient and other staff. Every institution considering the use of intrathecal catheters should establish a protocol. For labour analgesia, we recommend the use of dilute local anaesthetic agents and opioids. For caesarean section anaesthesia, gradual titration to the level of the fourth thoracic dermatome, with full monitoring, in a facility equipped to manage complications, should be performed using local anaesthetics combined with lipophilic opioids and morphine or diamorphine. Although evidence of the presence and duration of intrathecal catheters on the development of post-dural puncture headache and need for epidural blood patch is limited, we suggest considering leaving the intrathecal catheter in for 24 hours to reduce the chance of developing a post-dural puncture headache while maintaining precautions to avoid drug error and cerebrospinal fluid leakage. Injection of sterile normal saline into the intrathecal catheter may reduce post-dural puncture headache. The level of evidence for these recommendations was low.

A cluster quasi-randomized controlled trial of an interactive, monthly obstetric anesthesiology curriculum: impact on resident satisfaction and knowledge retention.

BACKGROUND: Increasingly, evidence supports the use of educational paradigms that focus on teacher-learner interaction and learner engagement. We redesigned our monthly obstetric anesthesia resident didactics from a lecture-based curriculum to an interactive format including problem-based learning, case discussion, question/answer sessions, and simulation. We hypothesized that the new curriculum would improve resident satisfaction with the educational experience, satisfaction with the rotation, and knowledge retention. METHODS: Fifty-three anesthesiology residents were prospectively recruited and quasi-randomized through an alternating-month pattern to attend either interactive sessions or traditional lectures. Residents completed a daily satisfaction survey about quality of teaching sessions and a comprehensive satisfaction survey at the conclusion of the rotation. Knowledge retention was assessed with a knowledge test completed on the final day. The primary outcome was daily satisfaction with the curriculum, and secondary outcomes included overall satisfaction with the curriculum, overall rotation satisfaction, and within-resident difference between pre- and post-knowledge test scores. RESULTS: No differences were observed in daily resident satisfaction after interactive sessions vs traditional lectures. Furthermore, no differences were observed between the interactive sessions and traditional lecture groups in overall satisfaction with the curriculum, overall satisfaction with the entire rotation or within-resident difference between pre- and post-knowledge test scores. CONCLUSIONS: Our study failed to demonstrate improvement in resident satisfaction or knowledge retention following implementation of an interactive curriculum on a month-long obstetric anesthesia rotation. Reasons may include misalignment of the intervention with measured study outcomes, lack of sensitivity of the survey tools, and inadequate training of faculty presenters.

Cytokines in the perinatal period - Part I.

Successful pregnancy requires a state of immune homeostasis. Maternal tolerance of the genetically distinct fetoplacental unit is in part mediated by maternal and fetal pro- and anti-inflammatory cytokines; these cytokines have also been implicated in different pregnancy-related pathologic states. This two-part series seeks to provide anesthesiologists with an overview on selected perinatal cytokines in an effort to identify opportunities for research and improvements in clinical care. In part one, we review basic and pregnancy-related elements of the immune system, with an emphasis on the role of cytokines. From this foundation, we offer a perspective of a unique phenomenon witnessed within obstetric anesthesia - maternal temperature elevation associated with labor epidural analgesia.

Cytokines in the perinatal period - Part II.

A contemporary, robust immunologic explanation for common obstetric conditions remains elusive; why some pregnant women are more susceptible to developing preeclampsia or preterm labor is not completely understood. We explore the immunology behind four important and commonly encountered pregnancy-related conditions: preeclampsia, recurrent miscarriage, preterm labor and gestational diabetes. For each condition, we summarize the current understanding of cytokines implicated in the pathogenesis, discuss the impact of anesthesia and analgesia on selected cytokine profiles, and suggest potential opportunities for clinical and research interventions.

Effect of neuraxial technique after inadvertent dural puncture on obstetric outcomes and anesthetic complications.

BACKGROUND: The aim of this study was to evaluate labor and delivery outcomes in parturients with inadvertent dural puncture managed by either insertion of an intrathecal catheter or a resited epidural catheter. METHODS: This was a retrospective cohort review of 235 parturients who had an inadvertent dural puncture during epidural placement over a six-year period. The primary outcome was the proportion of women with a delayed second stage of labor. Secondary outcomes were the proportion of cesarean deliveries, the proportion of cases resulting in post-dural puncture headache, and the incidence of failed labor analgesia. RESULTS: Baseline characteristics such as age, body mass index and parity were similar between the two groups. Among the 236 cases of inadvertent dural puncture, 173 women (73%) had an intrathecal catheter placed while 63 women (27%) had the epidural catheter resited. Comparing intrathecal with epidural catheters, there was no observed difference in the proportion of cases of prolonged second stage of labor (13% vs. 16%, P=0.57) and the overall rate of cesarean deliveries (17% vs. 16%, P=0.78). However, we observed a lower rate of post-dural puncture headache in women who had cesarean delivery compared to vaginal delivery (53% vs. 74%, P=0.007). A greater proportion of failed labor analgesia was observed in the intrathecal catheter group (14% vs. 2%, P=0.005). CONCLUSION: The choice of neuraxial technique following inadvertent dural puncture does not appear to alter the course of labor and delivery. Cesarean delivery decreased the incidence of post-dural puncture headache by 35%. Intrathecal catheters were associated with a higher rate of failed analgesia.

The effect of co-administration of intravenous calcium chloride and oxytocin on maternal hemodynamics and uterine tone following cesarean delivery: a double-blinded, randomized, placebo-controlled trial.

BACKGROUND: Oxytocin administration to prevent uterine atony following cesarean delivery is associated with adverse effects including hypotension, tachycardia, and nausea. Calcium chloride increases mean arterial pressure, systemic vascular resistance, and uterine smooth muscle contractility. This study evaluated whether the co-administration of calcium chloride with oxytocin following cesarean delivery could alter maternal hemodynamics. Secondary outcomes included uterine tone and blood loss. METHODS: Sixty healthy parturients with singleton, term, vertex pregnancies undergoing elective cesarean delivery under spinal anesthesia were randomized to one of three study solutions given intravenously immediately after umbilical cord clamping: (1) placebo, oxytocin 5U alone; (2) CA-200, oxytocin 5U+calcium chloride 200mg; or (3) CA-400, oxytocin 5U+calcium chloride 400mg. Blood pressure, heart rate, uterine tone, vasopressor or alternate uterotonic use and the incidence of nausea or vomiting were recorded. Baseline and intraoperative plasma concentration of ionized calcium and hematocrit were measured. RESULTS: Plasma concentration of ionized calcium was elevated in both study groups compared with placebo (P=0.001). Blood pressure decreased and heart rate increased in all groups (P <0.0001), with no differences between groups. No differences were observed between groups in uterine tone, vasopressor use, hematocrit change, estimated blood loss, incision-to-delivery interval, delivery-to-skin closure interval, total intravenous fluid administered or incidence of nausea. CONCLUSIONS: The decrease in blood pressure associated with oxytocin administration following cesarean delivery was not attenuated with co-administration of calcium chloride at the doses evaluated. Vasopressor use, uterine tone, and blood loss were also unaffected.

Differences between anticipated and perceived difficulty and insertion duration of labor epidural techniques among anesthesiologists, nurses and patients.

BACKGROUND: Difficulty with the labor epidural technique has been described using a variety of criteria, but remains inadequately defined. We sought to determine the reasons cited for difficulty with the insertion of labor epidural techniques among anesthesiologists, nurses, and patients. We hypothesized that the perception of procedural difficulty would correlate among participants and with the elapsed duration of the insertion attempt. METHODS: A total of 140 participant sets (i.e. anesthesiologist, nurse and patient) were asked to complete a questionnaire on procedural difficulty, immediately before (i.e. anticipated) and after (i.e. perceived) a standardized epidural technique. Procedural duration, using specified start and end times, was recorded in seconds by an independent co-investigator. Demographic data for all groups were recorded. RESULTS: Perceived difficulty with the epidural technique was similar among all groups (range 10-14%; P=0.29) and correlated with anticipated difficulty (anesthesiologist P=0.0004; nurse P=0.00001; patients P=0.006) and procedural duration (all groups P <0.001). The most common reasons cited for perceived difficulty were procedural duration (anesthesiologist P=0.58), number of attempts (nurse P=0.02), and pain experienced (patient P=0.035). CONCLUSIONS: Difficulty with the epidural technique is associated with anticipated difficulty and procedural duration. The reasons for perceived difficulty differ among anesthesiologists, nurses and obstetric patients, with patients most commonly citing pain experienced.

Emergent transesophageal echocardiography in hemodynamically unstable obstetric patients.

BACKGROUND: The obstetric population has an increasing incidence of comorbid conditions. These, coupled with the possibility of acute embolic events involving air, amniotic fluid, and thrombus, increase the likelihood of hemodynamic instability. Although the utility of transesophageal echocardiography to guide management in cardiac and high-risk, non-cardiac surgical populations has been well established, the emergent use in critically-ill parturients has not been comprehensively evaluated. METHODS: Using our departmental transesophageal echocardiography database of 28 293 examinations, parturients were identified who underwent emergent transesophageal echocardiography for evaluation of hemodynamic instability, including cardiac arrest, between January 1999 and March 2014. Transesophageal echocardiography findings and their impact on patient management were analyzed. RESULTS: Ten peripartum patients were evaluated. Six patients became unstable during dilation and evacuation procedures; one after a forceps delivery; one during and one after cesarean delivery; and one during a postpartum laparotomy. Six patients proceeded to cardiac arrest; however, all women survived their initial operation and resuscitation. Transesophageal echocardiography was instrumental in determining the etiology and guiding resuscitation in all 10 patients including emergent cardiac surgical intervention with cardiopulmonary bypass (n=2). Seven patients survived to hospital discharge, but three died after experiencing neurologic complications. CONCLUSIONS: Severe hemodynamic instability and cardiac arrest can occur in previously healthy parturients in pregnancy. Our data suggest that emergent transesophageal echocardiography is a valuable tool in determining the etiology and directing therapy of refractory hypotension or cardiac arrest in obstetric patients.

The effect of bupivacaine with fentanyl temperature on initiation and maintenance of labor epidural analgesia: a randomized controlled study.

BACKGROUND: Labor epidural analgesia is highly effective, but can be limited by slow onset and incomplete blockade. The administration of warmed, compared to room temperature, bupivacaine has resulted in more rapid onset epidural anesthesia. We hypothesized that the administration of bupivacaine with fentanyl at 37°C versus 20°C would result in improved initial and ongoing labor epidural analgesia. METHODS: In this prospective, randomized, doubled blinded study, 54 nulliparous, laboring women were randomized to receive epidural bupivacaine 0.125% with fentanyl 2 µg/mL (20 mL initial and 6 mL hourly boluses) at either 37°C or 20°C. Pain verbal rating scores (VRS), sensory level, oral temperature, and side effects were assessed after epidural loading (time 0), at 5, 10, 15, 20, 30, 60 min, and at hourly intervals. The primary outcome was the time to achieve initial satisfactory analgesia (VRS ⩽3). Secondary outcomes included ongoing quality of sensory blockade, body temperature and shivering. RESULTS: There were no differences between groups in patient demographics, initial pain scores, cervical dilatation, body temperature or mode of delivery. Epidural bupivacaine at 37°C resulted in shorter mean (±SD) analgesic onset time (9.2±4.7 vs. 16.0±10.5 min, P=0.005) and improved analgesia for the first 15 min after initial bolus (P=0.001-0.03). Although patient temperature increased during the study (P<0.01), there were no differences between the groups (P=0.09). Six (24%) and 10 (40%) patients experienced shivering in the 37°C and 20°C groups, respectively (P=0.23). CONCLUSIONS: The administration of epidural 0.125% bupivacaine with fentanyl 2µg/mL at 37°C versus 20°C resulted in more rapid onset and improved labor analgesia for the first 15 min. There was no evidence of improved ongoing labor analgesia or differences in side effects between groups.

Serum uric acid as a novel marker for uterine atony and post-spinal vasopressor use during cesarean delivery.

INTRODUCTION: Serum uric acid is a marker for oxidative stress in preeclampsia. Because oxidative stress can result in diminished uterine contractility and impaired vascular relaxation, we hypothesized that an elevated serum uric acid level in women undergoing neuraxial anesthesia for cesarean delivery would be associated with greater uterine atony, as measured by supplemental uterotonic agent use and blood loss, and less hypotension, as measured by total vasopressor use. METHODS: All records of patients (n=2527) undergoing cesarean delivery in 2009 were reviewed. Serum uric acid was measured within 24h of delivery in 509 patients; data from 345 patients with singleton pregnancies undergoing neuraxial anesthesia were analyzed. Demographic data, medical and obstetric history, anesthetic management and peripartum course were evaluated. ANOVA, Chi-square, and multivariate logistic and linear regression analyses were performed. RESULTS: Increased serum uric acid correlated positively with preeclampsia and the need for supplemental uterotonic agents (odds ratio 1.53, 95%CI 1.2-2.0, P=0.002), but not blood loss. The presence of preeclampsia also correlated with greater supplemental uterotonic agent use (P=0.01). The correlation between serum uric acid and post-spinal vasopressor use (i.e., none, moderate, and high) was of borderline significance (P=0.05). In patients without diabetes, serum uric acid levels correlated inversely with post-spinal vasopressor use (P=0.04). CONCLUSIONS: Elevated serum uric acid in parturients undergoing cesarean delivery with neuraxial anesthesia correlated with increased use of supplemental uterotonic agents and decreased use of post-spinal vasopressors. Further validation of this study is required to determine if serum uric acid in parturients can serve as a reliable predictor for higher and lower occurrences of uterine atony and spinal-induced hypotension, respectively.

Risk factors for failed conversion of labor epidural analgesia to cesarean delivery anesthesia: a systematic review and meta-analysis of observational trials.

BACKGROUND: This systematic review and meta-analysis evaluates evidence for seven risk factors associated with failed conversion of labor epidural analgesia to cesarean delivery anesthesia. METHODS: Online scientific literature databases were searched using a strategy which identified observational trials, published between January 1979 and May 2011, which evaluated risk factors for failed conversion of epidural analgesia to anesthesia or documented a failure rate resulting in general anesthesia. RESULTS: 1450 trials were screened, and 13 trials were included for review (n=8628). Three factors increase the risk for failed conversion: an increasing number of clinician-administered boluses during labor (OR=3.2, 95% CI 1.8-5.5), greater urgency for cesarean delivery (OR=40.4, 95% CI 8.8-186), and a non-obstetric anesthesiologist providing care (OR=4.6, 95% CI 1.8-11.5). Insufficient evidence is available to support combined spinal-epidural versus standard epidural techniques, duration of epidural analgesia, cervical dilation at the time of epidural placement, and body mass index or weight as risk factors for failed epidural conversion. CONCLUSION: The risk of failed conversion of labor epidural analgesia to anesthesia is increased with an increasing number of boluses administered during labor, an enhanced urgency for cesarean delivery, and care being provided by a non-obstetric anesthesiologist. Further high-quality studies are needed to evaluate the many potential risk factors associated with failed conversion of labor epidural analgesia to anesthesia for cesarean delivery.

Topical vasoconstrictor use for nasal intubation during pregnancy complicated by cardiomyopathy and preeclampsia.

Ankylosing spondylitis presents challenges for the obstetric anesthesiologist in administering neuraxial anesthesia or managing the airway. A pregnant patient with ankylosing spondylitis, cardiomyopathy and preeclampsia requiring cesarean delivery was managed with an awake nasotracheal fiberoptic intubation. The use of topical cocaine, epinephrine, phenylephrine, and oxymetazoline to produce nasal vasoconstriction is discussed. Selective alpha-2 agonists that can potentially provide nasal mucosa vasoconstriction and placental vasculature vasodilation are also discussed.