The multidisciplinary management of a mechanical mitral valve thrombosis in pregnancy: a case report and review of the literature.

Background: The management of anticoagulation for mechanical heart valves during pregnancy poses a unique challenge. Mechanical valve thrombosis is a devastating complication for which surgery is often the treatment of choice. However, cardiac surgery for prosthetic valve dysfunction in pregnant patients confers a high risk of maternofetal morbidity and mortality. Case summary: A 39-year-old woman in her first pregnancy at 30 weeks gestation presented to hospital with a mechanical mitral valve thrombosis despite therapeutic anticoagulation with low-molecular-weight heparin. She underwent an emergent caesarean section followed immediately by a bioprosthetic mitral valve replacement. This occurred after careful planning and organization on the part of a large multidisciplinary team. Discussion: A proactive, rather than reactive, approach to the surgical management of a mechanical valve thrombosis in pregnancy will maximize the chances of successful maternal and fetal outcomes.

An up-down determination of the required seated duration after intrathecal injection of bupivacaine and fentanyl for the prevention of hypotension during Cesarean delivery.

PURPOSE: A prolonged seated time after intrathecal injection of hyperbaric bupivacaine and morphine is related to the incidence of hypotension during Cesarean delivery, but results in a high incidence of pain during peritoneal closure. We conducted this study to determine the effect of the addition of intrathecal fentanyl on the relationship between seated time and hypotension and intraoperative analgesia requirements. METHODS: Women undergoing Cesarean delivery were randomized to receive an intrathecal injection of either 11.25 or 15 mg of hyperbaric bupivacaine with morphine 150 µg and fentanyl 15 µg using a combined spinal-epidural technique. The seated duration following intrathecal injection was assigned using up-down methodology. If the preceding patient was hypo- or normotensive, the next patient sat for 15 sec more or less, respectively. A systolic blood pressure < 80% of the preoperative value was defined as hypotension; a standardized anesthetic was administered, and the presence of pain during the procedure was recorded. Isotonic regression of pooled adjacent violators was used to determine the time at which 50% of each group would avoid hypotension (i.e., the median effective seated time). RESULTS: There were 15 patients in each group. The median seated time was 129 sec (95% confidence interval [CI], 116 to 150) for the 11.25-mg group and 459 sec (95% CI, 444 to 471) for the 15-mg group. Only one (3%) of the 30 patients in the study had pain on peritoneal closure, and this was successfully treated with intravenous fentanyl. CONCLUSION: We have determined the seated time required following intrathecal injection of hyperbaric bupivacaine, morphine, and fentanyl to prevent hypotension in 50% of patients undergoing Cesarean delivery. TRIAL REGISTRATION: www.clinicaltrials.gov , NCT01896960. Registered 2 July 2013.

The Labor Analgesia Requirements in Nulliparous Women Randomized to Epidural Catheter Placement in a High or Low Intervertebral Space.

BACKGROUND: We hypothesized that an epidural catheter placed in a lower vertebral interspace will require less medication for labor analgesia. METHODS: Nulliparous women requesting neuraxial labor analgesia were randomized to epidural catheter placement at the ultrasound-confirmed L1-2 or L4-5 interspace. Patient-controlled epidural analgesia and breakthrough manual epidural boluses of 10 mL of 0.125% bupivacaine with 50 µg of fentanyl or 8 mL of 2% lidocaine were utilized. Abdominal and perineal pain scores were assessed at 30 and 60 minutes after standardized initiation of epidural analgesia. Pain scores during pushing were assessed after delivery. The primary outcome was the proportion of patients requiring manual boluses and was compared using a χ test. Secondarily, we analyzed the number of boluses given in early (up to 4 hours before delivery) versus late labor using χ tests and the pain scores using Mann-Whitney U tests, with adjustment of P values for multiple testing. RESULTS: We analyzed 148 patients. Overall, the percentage of patients in the low versus high groups who required manual boluses was 46% vs 51% (P = 1.0). For the 56 patients in each group who delivered vaginally, 22 (52%) vs 20 (48%) manual boluses were given to the low epidural group in early versus late labor, compared to 9 (20%) vs 36 (80%) in the high epidural group (P = .014). There was no statistical difference in patient-controlled epidural analgesia requirements or patient satisfaction. Comparing the low versus high groups, the median (interquartile range) pain scores were: 3 (1, 6) vs 0 (0, 2) (P = .013) at 30 minutes and 1 (1, 3) vs 0 (0, 1) (P = .013) at 60 minutes for abdominal pain; 0 (0, 2) vs 1 (1, 3) (P = .36) and 0 (0, 1) vs 1 (1, 3) (P = .014) at these same time points for perineal pain; and 1 (0, 5) vs 0 (0, 3) (P = .9) for abdominal and 2 (0, 5) vs 4 (1, 8) (P = .025) for perineal pain during pushing. The percentage of patients who underwent instrumental delivery was 15% vs 5% (P = .06) for the low versus high group. CONCLUSIONS: An L4-5 epidural catheter initially provides less relief of abdominal pain but more relief of perineal labor pain. Patients with an L4-5 catheter require more manual boluses during early labor but less during late labor. The possible association of low epidural catheters with instrumental delivery merits further investigation.

Management of a Rare Complication of Epidural Analgesia in an Obese Laterally Positioned Parturient: Catheter Entrapment Next to the Inferior Vena Cava.

Intravascular, subdural, intrathecal, and subcutaneous placement of epidural catheters are known complications and common causes of anesthesia and analgesia failure. Because the epidural space is located near the retroperitoneum and catheters are placed blindly, it is possible that misplacement could involve other structures, including the inferior vena cava, the aorta, and the lumbar plexus. We report a case of an obese laterally positioned parturient who presented with an epidural catheter lodged in the retroperitoneum. The catheter provided inadequate analgesia for labor, and postpartum computed tomography revealed it to be located in the retroperitoneal space just adjacent to the inferior vena cava. Conventional removal techniques were unsuccessful, and the catheter was finally removed after insertion of a guide wire under fluoroscopy. We conclude that obesity and lateral positioning are factors that increase the risk of epidural catheter misplacement, and a large distance from skin to loss of resistance is a potential sign of misplacement. We recommend ultrasound imaging to aid in the insertion of epidural catheters in high-risk patients.

The median effective seated time for hypotension induced by spinal anesthesia at Cesarean delivery with two doses of hyperbaric bupivacaine: a randomized up-down sequential allocation study.

BACKGROUND: Extending the time a parturient is left sitting after induction of spinal anesthesia (i.e., the seated time) has had varying success in decreasing hypotension at Cesarean delivery. This may be due to the current lack of information concerning the dose-response relationship of seated time and rates of hypotension. METHODS: Term parturients scheduled for Cesarean delivery were randomized to receive 11.25 or 15.0 mg of 0.75% intrathecal hyperbaric bupivacaine, and they remained seated after injection for a length of time determined by an up-down sequential method. They were then placed in a wedged position and their blood pressure was measured every minute. Pre-delivery hypotension was considered present if there was a > 20% from baseline drop in systolic blood pressure. The seated time at which 50% of parturients avoided pre-delivery hypotension (median effective seated time) was determined with isotonic regression. RESULTS: Fifty patients were studied. For the 11.25-mg and 15.0-mg groups, the median effective seated time (95% confidence interval [CI]) was 130 sec (95% CI 117 to 150) and 385 sec (95% CI 381 to 396), respectively. CONCLUSIONS: There exists a seated time after intrathecal injection of hyperbaric bupivacaine where 50% of parturients do not experience hypotension. This seated time increases with an increased dose of bupivacaine. Further work is required to determine the full relationship between seated time and hypotension for other doses of anesthetic and to investigate the clinical utility of this technique for prevention of hypotension. This trial was registered at www.clinicaltrials.gov (NCT01561274).

Iliac artery rupture related to balloon insertion for placenta accreta causing maternal hemorrhage and neonatal compromise.

PURPOSE: The use of internal iliac artery balloons for prevention of hemorrhage in cases of placenta accreta is increasing. Most described complications of this technique are maternal and thromboembolic in nature. Complications related to vascular rupture are rare, their presentation is not well described, and the resultant neonatal consequences are infrequently reported. CLINICAL FEATURES: A 35-yr-old term parturient with suspected placenta accreta underwent prophylactic endovascular placement of iliac balloons prior to Cesarean delivery. The patient complained of contraction-like pain during balloon placement, and an arterial wall tear was discovered after abdominal incision. This produced significant maternal bleeding and the birth of a neonate with an umbilical venous pH of 6.95 and Apgar scores of 3 and 7. CONCLUSION: In addition to the known maternal risks, fetal risks must be considered when planning the placement of endovascular iliac balloons during pregnancy. We recommend continuous monitoring of maternal and fetal status when performing the procedure. Contraction-like pain during placement should raise the suspicion of arterial disruption.

Heart rate and blood pressure variability as markers of sensory blockade with labour epidural analgesia.

PURPOSE: To evaluate the correlation between the progression of somatosensory blockade and changes in autonomic outflow following the onset of labour epidural analgesia. METHODS: Twelve labouring parturients consented to participate in the study. Baseline electrocardiogram, blood pressure (BP) and respiratory rate were recorded for ten minutes. The epidural consisted of 0.125% bupivacaine with 50 microg of fentanyl (total volume 20 mL). Measurements were repeated for ten minutes after initiation of the block. The level of sensory block was measured bilaterally with loss of sensation to ice at two-minute intervals. Wavelet transform was used to obtain heart rate (HR) and BP variability every two minutes following the loading dose of epidural medication. High frequency power of HR variability was used to assess changes in parasympathetic activity. The total power of BP variability was used to assess changes in sympathetic activity. A nonparametric repeated measures ANOVA was used for the variability data, and a Spearman rank correlation test was used to evaluate the relationship between the sensory block and HR and BP variability. RESULTS: The sensory block progressed to T9 at ten minutes post-epidural and was the mirror image of the decrease in total power of BP variability. High frequency power of HR variability increased to a plateau at six minutes post-epidural. A significant correlation was found between the increase in sensory block and the observed decrease in BP variability (r = -1.000, P = 0.0028). CONCLUSION: In this study of labouring parturients, BP variability correlated with the progression of both sympathetic and somatosensory block following epidural anesthesia, while HR variability was shown to be a surrogate marker of increased parasympathetic activity.

Anesthetic management of a labouring parturient with urticaria pigmentosa.

PURPOSE: To report the anesthetic management of labour pain and Cesarean section in a patient with urticaria pigmentosa at risk for systemic mastocytosis. CLINICAL: A 37-yr-old patient with a history of urticaria pigmentosa and an allergic reaction to a local anesthetic agent was seen in consultation at 36 weeks gestation. She previously tested negative for an allergy test to lidocaine. Recommendations to avoid systemic mastocytosis included: avoidance of histamine-releasing drugs, using lidocaine for labour epidural, and regional anesthesia in case of a Cesarean section. The patient presented at term in labour. Intravenous fentanyl was used for early labour, followed by a combined spinal-epidural. The spinal contained lidocaine and fentanyl, but because of pruritus, the epidural infusion contained lidocaine only. Most likely because of tachyphylaxis to lidocaine, an epidural bolus of lidocaine with epinephrine failed to provide adequate anesthesia for a Cesarean section. The block was supplemented with nitrous oxide by mask, with fentanyl postdelivery. Postoperative pain control was managed with an epidural infusion of lidocaine and fentanyl for three days. The patient was discharged without complications four days postsurgery. CONCLUSION: Proper allergy testing prior to pregnancy is important to help the management of labour pain and anesthesia for Cesarean section in a patient at risk for systemic mastocytosis.

Autonomic nervous system response to epidural analgesia in laboring patients by wavelet transform of heart rate and blood pressure variability.

BACKGROUND: Epidurals are effective in relieving labor pain but result in a sympathectomy that may compromise maternal hemodynamic stability and fetal perfusion. Decreases in blood pressure and heart rate can be corrected, but markers of autonomic activity would be useful to predict and prevent such changes. The goal of this study was to find markers describing the changes in autonomic nervous system activity with epidural anesthesia in laboring patients. METHODS: The authors analyzed heart rate variability and blood pressure variability in 13 laboring patients using wavelet transform, a time-frequency analysis that accommodates rapid changes in autonomic activity. Heart rate and blood pressure variability were obtained 5 min before and 10 min after injection of 20 ml bupivacaine, 0.125%, and 50 microg fentanyl in the epidural space. RESULTS: Blood pressure and heart rate were not affected by epidural analgesia. However, high-frequency power of heart rate variability increased after epidural (increase in parasympathetic drive). The ratio of low-frequency:high-frequency power of heart rate variability decreased. High- and low-frequency power of blood pressure variability decreased (decrease in sympathetic outflow). CONCLUSIONS: Indices of parasympathetic and sympathetic activity after neuraxial blockade in laboring patients can be obtained by analysis of both heart rate variability and blood pressure variability. The analysis by wavelet transform can discern changes in autonomic activity when values of blood pressure and heart rate do not vary significantly. Whether this technique could be used to predict and prevent hemodynamic compromise after neuraxial blockade merits further studies.

Peripartum cardiomyopathy and thromboembolism; anesthetic management and clinical course of an obese, diabetic patient.

PURPOSE: To describe the anesthetic management and clinical course of a patient with peripartum cardiomyopathy. We highlight the frequent occurrence of thromboembolic morbidity in this group of parturients, emphasizing the need for early consideration of prophylactic anticoagulation. CLINICAL FEATURES: A 38-yr-old, diabetic, obese parturient was admitted with pulmonary edema and severe orthopnea at 31 weeks gestation. The respiratory rate was 44 breaths x min(-1), blood pressure 110/70 mmHg, pulse 120 beats x min(-1) and rales were heard in both lung fields. The diagnosis of peripartum cardiomyopathy was made based on sinus tachycardia with no evidence of ischemia on the electrocardiogram, and global left ventricular hypokinesis with an ejection fraction of 40-45% noted on transthoracic echocardiography. Cesarean delivery was planned to improve maternal respiratory status and hemodynamics. General anesthesia with invasive monitoring was planned, and surgery and anesthesia proceeded uneventfully. Less than 24 hr postoperatively, she sustained a thrombotic cerebral infarct leaving her hemiparetic and dysarthric. Subsequent investigations revealed a thrombophilic state due to elevated anticardiolipin antibody. CONCLUSION: General anesthesia is an acceptable option in parturients with heart failure secondary to cardiomyopathy. Thromboembolic complications are common, and early consideration should be given to prophylactic anticoagulation.