International Journal of Obstetric Anesthesia

Editorial Board

2012-04-01

The promise of pharmacogenetics in labor analgesia…tantalizing, but not there yet

C.A. Wong — 2012-03-14

It all seemed so simple. We envisaged that we would be able to predict how our patient would respond to a drug by doing simple genetic tests. We could then tailor drug administration to the test result. Those with insensitive receptors would receive a higher dose or different drug. Risk of toxicity would be reduced by identifying slow metabolizers. Ultimately, the drugs would be more effective and have fewer side effects, and patient outcomes would be improved. Unfortunately, although we may ultimately achieve this goal, we are not there, yet, at least not for opioids and their use for neuraxial labor analgesia. In fact, as the story unfolds and more research is published in this area, it may seem, at least to the average clinician, as though our understanding of the subject is becoming more muddled and confused, rather than less.

The transversus abdominis plane block and post-caesarean analgesia: are we any closer to defining its role?

N.J. McDonnell, M.J. Paech — 2012-03-14

The provision of high-quality pain relief after caesarean delivery is something that women desire and obstetric anaesthetists aspire to provide. The reality is that this can be a somewhat lofty ambition, for a variety of reasons such as difficulty predicting an individual’s pain, inter-patient variability in the analgesic response and contraindications to certain techniques. Furthermore, resource limitations may exist, such as the inability to provide an appropriate level of post-operative care following neuraxial morphine or there may be a lack of equipment for example, patient-controlled epidural analgesia pumps. Consequently, there is no universally accepted ‘gold standard’ method of post-caesarean analgesia with most units having preferred approaches that work well for the majority of women for whom they care.

A randomized controlled trial comparing intrathecal morphine with transversus abdominis plane block for post-cesarean delivery analgesia

H. Loane, R. Preston, M.J. Douglas, S. Massey, M. Papsdorf, J. Tyler — 2012-03-14

Abstract: Background: Intrathecal morphine is an effective analgesic post-cesarean delivery; however, it may be contraindicated or unsuitable in some patients. We compared the efficacy and side effects of intrathecal morphine with an ultrasound-guided transversus abdominis plane (TAP) block in a randomized, controlled, double-blinded trial. The primary outcome was the morphine equivalents dose used in the first 24h post-surgery. Secondary outcomes were pain scores and side effects, including pruritus, sedation, nausea and vomiting.Methods: Planned recruitment was for 90 women; however, the study was terminated early. Sixty-nine women undergoing elective cesarean delivery under spinal anesthesia were enrolled. They were randomized to receive either intrathecal morphine 100μg plus a sham TAP block or a TAP block with 0.5% ropivacaine 1.5mg/kg, to each side to a maximum of 20mL. Women were assessed at 2, 6, 10, 24h and 3 months post-spinal.Results: Sixty-six women completed the trial. The morphine equivalents dose used in the TAP block group was greater at 24h compared with the intrathecal morphine group (7.5mg (95% CI 4.8–10.2) vs. 2.7mg (95% CI 1.0–4.3), F [1, 64]=9.62, P=0.003). There was no difference at 2, 6, or 10h. Pain scores on rest and movement were higher in the TAP block group at all times although this only reached statistical significance at 10h (P=0.001). Nausea and vomiting (P=0.02) and pruritus (P=0.007) were lower in the TAP block group.Conclusions: In this trial, the TAP block was associated with greater supplemental morphine requirements and higher pain scores than intrathecal morphine but fewer opioid-related side effects. The TAP block may be a reasonable alternative when intrathecal morphine is contraindicated or not appropriate.

Continuous wound infusion with ropivacaine fails to provide adequate analgesia after caesarean section

2012-02-20

Abstract: Background: Continuous wound infusion with local anaesthetic has been used in post-caesarean pain management with conflicting results. We carried out a study comparing three groups: continuous ropivacaine wound infusion, intrathecal morphine with saline wound infusion and saline wound infusion only.Methods: Sixty-six women undergoing elective caesarean section under combined spinal-epidural anaesthesia were randomly allocated to receive intrathecal morphine with saline wound infusion or 48h continuous wound infusion with either ropivacaine or saline. All parturients received oral ketoprofen and intravenous oxycodone patient-controlled analgesia. Consumption of oxycodone, visual analogue scale pain scores (0–10cm), patient satisfaction, side effects and recovery parameters were recorded for 48h in a double-blind manner.Results: Continuous wound infusion with ropivacaine failed to reduce oxycodone consumption or pain scores compared with saline control. In the first 24h intrathecal morphine reduced mean oxycodone consumption compared to the ropivacaine wound infusion group (26mg vs. 48mg, P=0.007) and saline wound infusion group (26mg vs. 45mg, P=0.021). The first 24-h mean pain score was also lower in the intrathecal morphine group vs. the saline wound infusion group (1.3 vs. 2.2, P=0.021). Pain scores were not significantly different between intrathecal morphine and ropivacaine wound infusion groups. Pruritus was more common with intrathecal morphine.Conclusion: Compared to saline control, continuous wound infusion with ropivacaine failed to reduce the use of intravenous oxycodone patient-controlled analgesia or pain scores. Intrathecal morphine decreased oxycodone consumption by 46% in the first 24h after surgery when compared to continuous ropivacaine wound infusion.

Pharmacokinetics of a loading dose of intravenous paracetamol post caesarean delivery

2012-02-17

Abstract: Background: The postpartum period affects drug disposition, but data of intravenous paracetamol loading dose pharmacokinetics immediately following caesarean delivery have not yet been reported.Methods: Immediately following caesarean delivery, women received a 2-g loading dose of intravenous paracetamol. Plasma samples were collected at 1, 2, 4 and 6h. Individual pharmacokinetics were calculated assuming a linear one-compartment model with instantaneous input and first-order output. Data were reported using median and range.Results: Twenty-eight patients undergoing caesarean delivery were recruited (age 31.5 [20–42] years, weight 79 [57–110] kg, body surface area 1.9 [1.5–2.4]m2). Median paracetamol plasma concentrations after 1, 2, 4 and 6h were 22.5, 15.25, 7.9, and 3.9mg/L respectively. Paracetamol clearance was 20.3 (11.8–62.8) L/h or 10.9 (7–23.8)L/hm2, distribution volume 58.3 (42.9–156) L or 0.72 (0.52–1.56) L/kg.Conclusion: Pharmacokinetics of intravenous paracetamol have been estimated following caesarean delivery. Although limited to a loading dose shortly after surgery, the results are clinically relevant since this is the first description in this patient population. These data provide evidence on which to base further integrated pharmacokinetic/pharmacodynamic studies in peripartum analgesia.

Haemodynamics in obese pregnant women

A.T. Dennis, J.M. Castro, M. Ong, C. Carr — 2012-02-13

Abstract: Background: Obesity in pregnant women is a serious health issue. Invasive monitoring devices are rarely used in pregnancy due to their risks; however, assessment of cardiac function is often required in these women. Transthoracic echocardiography offers advantages but may be technically difficult to perform. Our aim was to determine the feasibility of transthoracic echocardiography and to quantify left ventricular function and structure using transthoracic echocardiography in obese pregnant women.Method: Fifteen obese but otherwise healthy pregnant women (body mass index >30kg/m2), were compared with 40 healthy non-obese pregnant women. Echocardiography was performed according to American Society of Echocardiography recommendations.Results: Test completion with key haemodynamic data were obtained in 100% of women. Gestational age (Mean±SD) was similar between groups (36±5weeks). Compared with non-obese pregnant women, obese pregnant women had elevated mean arterial pressure (88±6 vs. 81±8mmHg, P=0.003), increased left ventricular mass (162.8±35.4 vs. 130.8±21.0g, P=0.008) but similar cardiac output (4417±890 vs. 4109±595mL/min, P=0.230) and diastolic changes (mitral valve E/se′ > 8 in 33% vs. 15% of patients, P=0.26). Septal tissue Doppler indices in obese pregnant women were s′ 9.1±1.9cm/s, e′ 11.6±2.6cm/s, a′ 8.1±2.7cm/s. Tei index was reduced in both groups (0.49±0.12 vs. 0.42±0.09, P=0.05).Conclusions: Transthoracic echocardiography was used to delineate haemodynamics in obese pregnant women. Mean arterial blood pressure and left ventricular mass were increased in obese pregnant woman. The incidence of diastolic impairment and reduced myocardial performance were similar between groups.

Measurement of intra-abdominal pressure in term pregnancy: a pilot study

R. Chun, L. Baghirzada, C. Tiruta, A.W. Kirkpatrick — 2012-02-13

Abstract: Background: This study was conducted to assess the feasibility of measuring intra-abdominal pressure in term parturients under spinal anesthesia.Methods: Intra-abdominal pressure was measured in 20 term parturients after spinal anesthesia for elective caesarean section. Pressure was measured in the supine and 10° left lateral tilt positions with a constant reference point throughout.Results: Intra-abdominal pressure measurement was feasible and safe to perform. Pressure was significantly lower in the left lateral tilt position than supine (10.9mmHg±4.67 vs. 8.9mmHg±4.87, P=0.0004). The range of intra-abdominal pressure in pregnancy was wide, from 2 to 20mmHg, with >25% of patients resting with pressures above 12mmHg in both positions.Conclusions: Under spinal anesthesia, intra-abdominal pressure in >25% of healthy term parturients was > 12mmHg, which has conventionally been defined as intra-abdominal hypertension. The intra-abdominal pressure in term pregnancy should be performed in the left lateral tilt position to avoid falsely elevated pressure measurements.

A sequential compression mechanical pump to prevent hypotension during elective cesarean section under spinal anesthesia

N. Sujata, D. Arora, B.P. Panigrahi, V.M. Hanjoora — 2012-03-07

Abstract: Background: Spinal anesthesia is a standard technique for cesarean section but can cause hypotension which may be related to venous pooling secondary to progesterone-induced decreases in vascular tone. This study investigated the use of a sequential compression mechanical pump with thigh-high sleeves with compression cycles timed to venous refilling. We hypothesized that this would recruit pooled venous blood from the lower limbs, maintain the central blood volume and thus decrease the incidence of hypotension.Methods: One hundred parturients scheduled for elective cesarean section under spinal anesthesia were recruited and randomly assigned to use of either a mechanical pump (Group M) or control (Group C). A standardized protocol for co-hydration and anesthesia was followed. Hypotension, defined as a decrease in systolic blood pressure by >20% from baseline, was treated with 6-mg boluses of intravenous ephedrine. The incidence of hypotension was defined as the primary outcome. Median ephedrine requirement was taken as a measure of the severity of hypotension.Results: Hypotension occurred in 12 of 47 (25.5%) patients in Group M compared to 27 of 45 (60%) in Group C (P=0.001). The median [range] ephedrine dose was greater in Group C (12 [0–24]mg) compared to Group M (0 [0–12]mg) (P<0.001). There was no difference between groups in the time to onset of hypotension.Conclusion: The use of a sequential compression mechanical pump that detects venous refilling and cycles accordingly, reduced the incidence and severity of hypotension after spinal anesthesia for cesarean section.

The Analgesia Nociception Index: a pilot study to evaluation of a new pain parameter during labor

2012-02-23

Abstract: Background: Objective pain assessment that is not subject to influences from either cultural or comprehension issues is desirable. Analysis of heart rate variability has been proposed as a potential method. This pilot study aimed to assess the performance of the PhysioDoloris™ analgesia monitor which calculates an Analgesia Nociception Index derived from heart rate variability. It was compared with visual analogical pain scores.Methods: Forty-five parturients who requested epidural analgesia were recruited. Simultaneous couplets of pain scores and Analgesia Nociception Index values were recorded every 5min regardless of the presence or absence of uterine contractions. The relationship between indices was characterized, and a cut-off value of Analgesia Nociception Index corresponding to a visual analogical score >30 (range 0–100) was used to determine the positive and negative predictive value of the Analgesia Nociception Index.Results: There was a negative linear relationship between visual analogical pain scores and Analgesia Nociception Index values regardless of the presence of uterine contractions (regression coefficient±SEM=−0.18±0.032 for entire dataset). Uterine contraction significantly reduced the Analgesia Nociception Index (P<0.0001). Using a visual analogical pain score >30 to define a painful sensation, the lower 95% confidence limit for the Analgesia Nociception Index score was 49.Conclusion: The Analgesia Nociception Index has an inverse linear relationship with visual analogical pain scores. Further studies are necessary to confirm the results of this pilot study and to look at the influence of epidural analgesia on the Analgesia Nociception Index.

Maternal anesthesia and fetal neurodevelopment

A. Palanisamy — 2012-03-14

Abstract: It is clear from animal studies that commonly used anesthetic agents affect early brain development both histologically and functionally. With human epidemiologic evidence suggesting an association between anesthesia and surgery early in life and late-onset learning disabilities, investigators have focused their attention on the subtle long-term effects of anesthesia exposure. Most obstetric anesthesia studies, however, have focused on either the teratogenic effects of anesthetic agents in the first trimester or on the neonatal status immediately after delivery. Not much attention has been paid to the human second trimester, a period of active fetal brain development typified by neurogenesis and neuronal migration. Of concern though, is that these events are easily perturbed by environmental and pharmacological influences. New research studies have raised significant questions about the fetal impact of maternal anesthesia for non-obstetric and fetal surgery. This review summarizes the major findings in the field of developmental neurotoxicity of anesthetic agents, discusses the susceptibility of the fetal brain to anesthetic effects in a trimester-specific style, and outlines the pitfalls in extrapolating animal research to humans.

Tramadol in pregnancy and lactation

M. Bloor, M.J. Paech, R. Kaye — 2012-02-10

Abstract: Tramadol produces analgesic effects through both non-opioid and weak opioid activity and is commonly used to treat mild to moderate pain. It has been in use for over 30years and has a well-established safety profile in the general population. Since tramadol is not licensed for use in pregnancy and lactation, there is limited clinical research on its use in this patient population. A systematic review was undertaken of articles published in English before June 2011, searching Pubmed, Medline, CINAHL, Embase and Cochrane databases using the terms ‘tramadol and pregnancy’, ‘tramadol and breastfeeding’, ‘tramadol and lactation’, and ‘tramadol and neonate’.

The 2011 FAER-SOAP Gertie Marx lecture Reflections on studies of epidural analgesia and obstetric outcome

D.H. Chestnut — 2012-02-16

It was a privilege for me to know Dr. Gertie Marx. Time does not allow me to give adequate tribute to her contributions to the practice of obstetric anesthesia. In 2000 Dr. Marx received the first Distinguished Service Award from the Society for Obstetric Anesthesia and Perinatology (SOAP). As President of SOAP that year, it was my privilege to present the award to Dr. Marx. At the meeting banquet, four of us – Callie Hoyt, Medge Owen, Dick Wissler, and I – sang a song – barbershop quartet style – to Dr. Marx. The words were written by Dick Wissler and were quite clever. As I recall the singing was not stellar, but I think that Dr. Marx enjoyed it, and it was a lot of fun.

Transversus abdominis plane catheters for post-cesarean delivery analgesia: a series of five cases

L. Bollag, P. Richebe, C. Ortner, R. Landau — 2011-12-07

Abstract: We present five cases of women who received ultrasound-guided transversus abdominis plane catheters for post-cesarean delivery analgesia. Pain relief was maintained with repeated boluses of local anesthetic combined with oral acetaminophen and ibuprofen unless contraindicated. We conclude that repeated dosing through transversus abdominis plane catheters may be offered to women as an alternative or adjuvant to intrathecal morphine. Larger studies to evaluate the safety and further refinements of this novel procedure are warranted.

Acute intrathecal haematoma following neuraxial anaesthesia: diagnostic delay after apparently normal radiological imaging

M.A. Walters, M. Van de Velde, G. Wilms — 2012-02-16

Abstract: We describe a case of intrathecal haematoma following combined spinal-epidural anaesthesia for caesarean section. The parturient was previously well with no risk factors for haematoma development. Surgical intervention was delayed, resulting in permanent neurological injury. Incorrect interpretation of clinical findings and magnetic resonance imaging contributed to the delay in definitive treatment. We discuss the difficulties in diagnosis, image interpretation and the need for a specialist opinion when abnormal neurological symptoms persist despite apparently normal imaging.

Anesthetic management of a spontaneous spinal-epidural hematoma during pregnancy

Y.Y. Jo, D. Lee, Y.J. Chang, H.J. Kwak — 2012-02-17

Abstract: Spontaneous spinal-epidural hematoma is uncommon and rare during pregnancy. We were presented with a 31-year-old patient who developed back pain with lower extremity paralysis at 36weeks of gestation. A magnetic resonance imaging scan demonstrated an acute spinal-epidural hematoma and therefore, an emergency cesarean delivery was performed followed by hemilaminectomy with hematoma removal. Anesthesia was initiated with a volatile-based technique which, following delivery of the baby, was changed to target-controlled infusions of propofol and remifentanil. Postoperatively, dopamine was infused to maintain the blood pressure within the high-normal range to optimize spinal cord perfusion. Successful anesthetic and postoperative management is described together with a review of the literature.

Subdural hematoma after an epidural blood patch

L.A. Verduzco, S.W. Atlas, E.T. Riley — 2012-02-10

Abstract: We report the case of a 37-year-old postpartum patient who developed a contained subacute spinal subdural hematoma causing mass effect on the cauda equina and severe spinal stenosis after undergoing an epidural blood patch for postdural puncture headache. Recovery occurred following administration of oral steroids.

A combined spinal-epidural technique for labor analgesia and symptomatic relief in two parturients with idiopathic intracranial hypertension

R.C. Month, S.J. Vaida — 2012-02-13

Abstract: Idiopathic intracranial hypertension is a condition consisting of increased intracranial pressure of unknown etiology, predominantly affecting obese women of childbearing age. Symptomatic relief can be provided by lumbar puncture and withdrawal of cerebrospinal fluid, and the technique has been described in laboring women using an intrathecal catheter. We present two patients who achieved both labor analgesia and symptomatic relief via a combined spinal-epidural technique with small volume cerebrospinal fluid withdrawal. Both women complained of headache of at least a 5 on a 10-point pain scale at the time of labor induction. Between 5 and 6mL of cerebrospinal fluid were withdrawn at the time of combined spinal-epidural insertion and pain relief was successfully achieved with patient-controlled epidural anesthesia. One patient proceeded to cesarean delivery for fetal indications under epidural anesthesia. Both women described significant improvement in headache symptoms that persisted until discharge from hospital, and neither developed new neurologic symptoms. A combined spinal-epidural technique with a small volume of cerebrospinal fluid withdrawal may provide labor analgesia and symptomatic relief in the parturient with idiopathic intracranial hypertension.

Two doses of spinal bupivacaine for caesarean delivery in severe preeclampsia: a pilot study

K. Jain, J.K. Makkar, S. Yadanappudi, I. Anbarasan, S. Gander — 2012-02-17

Spinal anaesthesia-induced hypotension may decrease uteroplacental perfusion in severely preeclamptic women undergoing caesarean delivery. In this pilot study, we aimed to determine whether a reduction in the dose of spinal bupivacaine decreased the incidence of hypotension and the requirement for vasopressors in this group of women.

Combined spinal-epidural anesthesia for cesarean delivery in a patient with capillary pontine telangiectasia

R. Month, S. Vaida, A. Budde — 2012-02-10

Capillary pontine telangiectasia (CPT) are vascular malformations in which thin-walled, dilated capillary spaces are interspersed in normal parenchymal tissue. The condition has an incidence of 0.1% in the general population. The majority are found incidentally since they tend to grow slowly, but they may rarely present with mild symptoms including headache, vertigo, or facial weakness. Hemorrhage from CPT is rare.

Anesthetic management of a pregnant patient with multiple pterygium syndrome (Escobar type)

W.D. Stoll, L. Hebbar, L.S. Marica — 2012-02-10

Multiple pterygium syndrome is a rare disorder with several subtypes. Its features include pterygia (excessive webbing), arthrogryposis (congenital contractures), ankyloglossia (adhesions of the tongue to the palate), syngnathia (congenital bands of tissue between the maxilla and mandible), cleft palate, micrognathia, scoliosis, short stature, craniofacial dysmorphism, arachnodactyly and congenital respiratory distress. The Escobar subtype includes webbing of the neck that increases with age, lumbar lordosis and webbing of the elbows and knees that develops before adolescence.

Magnetic resonance imaging of sciatic nerve compression injury after epidural blockade

D.M. Mumby, E.L. Hartsilver — 2012-02-15

A fit 32-year-old nulliparous woman presented at term in spontaneous labour requesting epidural analgesia. In the sitting position, an epidural catheter was inserted at L2–3 at the first attempt, without paraesthesia. A loading dose of bupivacaine 15mg and fentanyl 30μg achieved effective analgesia with a block height to ice of T10 bilaterally. An infusion of 0.1% bupivacaine plus fentanyl 2μg/mL was started at 10mL/h. The infusion continued to provide excellent analgesia for the next 8h, at which time the woman gave birth to a healthy infant by normal vaginal delivery. After delivery of the placenta the epidural infusion was stopped and the epidural catheter removed.

Shoulder-tip pain as an indicator of uterine rupture with a functioning epidural

M. Lenihan, A. Krawczyk, C. Canavan — 2012-03-07

Uterine rupture in pregnancy is a rare and potentially catastrophic complication. Symptoms and signs are typically non-specific but include a non-reassuring fetal heart rate trace, disproportionate abdominal pain and maternal collapse.

Management of an unusual major obstetric haemorrhage in a resource-poor setting

L. Peltola, G. Pollach, E. Borgstein — 2012-03-09

A 35-year-old ASA 1, G7P6 woman was referred to Queen Elizabeth Central Hospital, Malawi, with right upper quadrant pain and ultrasound report suggesting a 23week, 600g live extrauterine fetus with hepatic placental implantation. She was scheduled for urgent caesarean delivery. The anaesthetists were informed of the case on the morning of surgery. The patient had a clear chest and no heart murmurs. Her blood pressure (BP) was 120/70mmHg and heart rate 90 beats/min. Preoperative bloods included haemoglobin (Hb) 8.7g/dL and platelets 357×109/L. Neither clotting studies nor urea and electrolytes were available. With a high risk of bleeding, surgery proceeded once blood products consisting of whole blood 1500mL and two units of fresh frozen plasma (FFP) were confirmed. Senior surgeons and anaesthetists were present and a postoperative intensive care unit (ICU) bed was available.

Successful resuscitation following amniotic fluid embolism in a patient undergoing induction of labour for late miscarriage

F. Wallace, R. Clayton, S. Davies, S. Saleh — 2012-03-09

Amniotic fluid embolism (AFE) is a rare but poorly understood condition that contributes significantly to maternal morbidity and mortality. Classical presentation occurs during labour or shortly postpartum with cardiovascular, respiratory or neurological collapse, or disseminated intravascular coagulopathy (DIC). The clinical course is rapidly progressive and life-threatening. Mortality rates have improved significantly and were recently quoted as 20%, but analysis of the US registry revealed neurological impairment in 85% of survivors. We report successful cardiopulmonary resuscitation (CPR) following induction of labour for late miscarriage.

Accidental epidural administration of Syntocinon

M.J. Ross, A. Wise — 2012-03-14

We report a case of accidental epidural administration of Syntocinon and present four additional cases notified to the manufacturer. A 20-year-old nulliparous woman presented at 41weeks of gestation for induction of labour following a small antepartum haemorrhage. Epidural analgesia worked well for the duration of her labour but, despite maximal oxytocin therapy, labour did not progress adequately and caesarean delivery was performed. Ten units of Syntocinon (Alliance Pharma, Camridge, UK) diluted in 0.9% saline (1IU/mL) had been prepared before delivery. Immediately after umbilical cord clamping, Syntocinon 5IU was administered inadvertently into the epidural catheter via the anti-bacterial filter, which was taped to the patient’s pillow adjacent to the intravenous injection port. The error was immediately identified, but no fluid could be aspirated from the epidural catheter. A further 5IU of Syntocinon were given intravenously. Persistent uterine atony responded to an additional 5-IU bolus and subsequent infusion. The patient remained comfortable and physiologically stable throughout surgery despite an estimated blood loss of 1200mL. The patient was informed of the error. The patient’s follow-up at 2, 4, 6weeks and 12months post-partum revealed no sequelae from epidural Syntocinon administration.

Corrigendum to “Increased anaesthetic workload associated with increased maternal age” (Int J Obstet Anesth 2012; 21: 100–1)

L. Peltola, J. Mayer, J. Cook, R. Bedson, L. Arrandale — 2012-03-14

The authors regret that in lines 15–17 of this letter the statistics are in the wrong order. These lines should read: “both for nulliparous (70% vs. 63%) and multiparous groups (54% vs. 43%).”