Roshan Fernando

The effect of posture and baricity on the spread of intrathecal bupivacaine for elective cesarean delivery.

Posture and baricity during induction of spinal anesthesia with intrathecal drugs are believed to be important in determining spread within the cerebrospinal fluid. In this double-blind prospective study, 150 patients undergoing elective cesarean delivery were randomized to receive a hyperbaric, isobaric, or hypobaric intrathecal solution of 10 mg bupivacaine during spinal anesthesia induced in either the sitting or right lateral position. After an intrathecal injection using a combined-spinal technique patients were placed in the supine wedged position. We determined the densities of the three intrathecal solutions from a previously validated formula and measured using a DMA-450 density meter. Data collection included sensory level, motor block, episodes of hypotension, and ephedrine use. Statistical analysis included analysis of variance and Cuzick’s trend. In the lateral position, baricity had no effect on the spread of sensory levels for bupivacaine compared to the sitting position, where there was a statistically significant difference in spread with the hypobaric solution producing higher levels of analgesia than the hyperbaric solution (P = 0.002). However, the overall differences in maximal spread only differed by one dermatome, with the hyperbaric solution achieving a median maximum sensory level to T3 compared with T2 for the isobaric and hypobaric solutions. Motor block was significantly (P = 0.029) reduced with increasing baricity and this trend was significant (P = 0.033) for the lateral position only. Hypotension incidence and ephedrine use increased with decreasing baricity (P = 0.003 and 0.004 respectively), with the hypobaric sitting group having the most frequent incidence of hypotension (76%) as well as cervical blocks (24%; P = 0.032).

Suprasternal Doppler Estimation of Cardiac Output: Standard Versus Sequential Combined Spinal Epidural Anesthesia for Cesarean Delivery

BACKGROUND:Sequential (Seq) combined spinal epidural (CSE) may provide better cardiovascular stability than standard (Std) CSE for cesarean delivery. We compared the cardiovascular stability of both techniques using suprasternal Doppler. METHODS:Healthy women (n = 40) scheduled for elective cesarean delivery were randomized into two groups; Std or Seq CSE. Serial measures of cardiac output indices, including minute distance, stroke distance, stroke volume, peak velocity, and corrected flow time, were recorded before and after intravascular fluid administration and after CSE. Women received either hyperbaric bupivacaine 10 mg (Std) or 5 mg (Seq) with intrathecal fentanyl 15 &mgr;g. An epidural top-up with bupivacaine 0.5% w/v (5 mL at 20 min in the Std group and 10 mL at 15 min followed by 5 mL at 25 min in the Seq group) was given if predefined sensory targets were not met. Data were collected every 5 min after intrathecal injection. Hypotension was treated with ephedrine. Statistical analyses included repeated measures analysis of variance, analysis of covariance and Student’s t-test. P < 0.05 denoted significance. RESULTS:Results showed no difference in cardiac output, minute distance, stroke distance, stroke volume, peak velocity, or corrected flow time between groups over the first 20 min after spinal injection. For whole measurement periods, mean lowest values for these same measures showed no group differences. CONCLUSION:We therefore found no benefit in terms of cardiovascular stability of Seq to Std CSE for elective cesarean delivery in the healthy pregnant population.

Predicting the density of bupivacaine and bupivacaine-opioid combinations.

IMPLICATIONS Manipulating the density of local anesthetic solutions by using a simple formula may be clinically useful in producing optimal density solutions for spinal anesthesia under a variety of clinical conditions.

International consensus statement on the management of hypotension with vasopressors during caesarean section under spinal anaesthesia

1 Consultant, Department of Anaesthesia, St Michael’s Hospital, Bristol, UK 2 Professor, Department of Anesthesiology, Stanford University School of Medicine, Stanford, CA, USA 3 Professor Emeritus, Department of Anaesthesia and Peri-operative Medicine, University of Cape Town, Cape Town, South Africa 4 Senior Consultant, Department of Anaesthesia, Hamad Women’s Hospital, Doha, Qatar 5 Clinical Associate Professor, Department of Anaesthesia and Pain Medicine, King Edward Memorial Hospital for Women, Subiaco, Australia 6 Professor, D epartement d’Anesth esie-R eanimation, Hôpital Antoine B ecl ere, Clamart, France 7 Assistant Professor, Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, USA 8 Professor and Senior Consultant, Department of Women’s Anaesthesia, KKWomen’s and Children’s Hospital, Singapore 9 Chair, Department of Anesthesiology, UZ Leuven, Leuven, Belgium 10 Professor of Anesthesiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium 11 Consultant, Department of Anaesthesia and Intensive Care Medicine, King’s College Hospital NHS Foundation Trust, London, UK

Combined spinal epidural vs epidural labour analgesia: does initial intrathecal analgesia reduce the subsequent minimum local analgesic concentration of epidural bupivacaine?

Labour analgesia initiated using a combined spinal‐epidural (CSE) technique may reduce subsequent epidural bupivacaine requirements compared with an epidural‐only technique. We compared the minimum local analgesic concentrations (MLAC) of epidural bupivacaine following initial intrathecal or epidural injection. In a prospective, double‐blind study, 115 women requesting epidural analgesia were randomly assigned to receive either an epidural with bupivacaine 20 mg and fentanyl 40 μg or a CSE with intrathecal bupivacaine 2.5 mg and fentanyl 5 μg. Analgesia was assessed using a visual analogue pain score. When further analgesia was requested, bupivacaine 20 ml was given, and the concentration was determined using the technique of up‐down sequential allocation. The MLAC of bupivacaine in the epidural group was 0.032% wt/vol (95% CI 0.020–0.044) compared with 0.047% wt/vol (95% CI 0.042–0.052) in the CSE group. Bupivacaine requirements for the second injection were increased following intrathecal analgesia by a factor of 1.45 (p = 0.026) compared with epidural analgesia.

Inflammation and Epidural-Related Maternal Fever: Proposed Mechanisms.

Intrapartum fever is associated with excessive maternal interventions as well as higher neonatal morbidity. Epidural-related maternal fever (ERMF) contributes to the development of intrapartum fever. The mechanism(s) for ERMF has remained elusive. Here, we consider how inflammatory mechanisms may be modulated by local anesthetic agents and their relevance to ERMF. We also critically reappraise the clinical data with regard to emerging concepts that explain how anesthetic drug–induced metabolic dysfunction, with or without activation of the inflammasome, might trigger the release of nonpathogenic, inflammatory molecules (danger-associated molecular patterns) likely to underlie ERMF.

The Society for Obstetric Anesthesia and Perinatology Consensus Statement on the Anesthetic Management of Pregnant and Postpartum Women Receiving Thromboprophylaxis or Higher Dose Anticoagulants

Venous thromboembolism is recognized as a leading cause of maternal death in the United States. Thromboprophylaxis has been highlighted as a key preventive measure to reduce venous thromboembolism–related maternal deaths. However, the expanded use of thromboprophylaxis in obstetrics will have a major impact on the use and timing of neuraxial analgesia and anesthesia for women undergoing vaginal or cesarean delivery and other obstetric surgeries. Experts from the Society of Obstetric Anesthesia and Perinatology, the American Society of Regional Anesthesia, and hematology have collaborated to develop this comprehensive, pregnancy-specific consensus statement on neuraxial procedures in obstetric patients receiving thromboprophylaxis or higher dose anticoagulants. To date, none of the existing anesthesia societies’ recommendations have weighed the potential risks of neuraxial procedures in the presence of thromboprophylaxis, with the competing risks of general anesthesia with a potentially difficult airway, or maternal or fetal harm from avoidance or delayed neuraxial anesthesia. Furthermore, existing guidelines have not integrated the pharmacokinetics and pharmacodynamics of anticoagulants in the obstetric population. The goal of this consensus statement is to provide a practical guide of how to appropriately identify, prepare, and manage pregnant women receiving thromboprophylaxis or higher dose anticoagulants during the ante-, intra-, and postpartum periods. The tactics to facilitate multidisciplinary communication, evidence-based pharmacokinetic and spinal epidural hematoma data, and Decision Aids should help inform risk–benefit discussions with patients and facilitate shared decision making.

Density Determination of Bupivacaine and Bupivacaine-opioid Mixtures for Spinal Anesthesia

We appreciate Dr. Fattorutto’s interest in our case report and his passion in his opinions. Unfortunately, however, we fail to understand on what basis he draws the conclusion that the PFA-100 is insensitive to platelet dysfunction induced by clopidogrel. Indeed, the studies cited by Dr. Fattorutto support the use of the PFA-100 for this very purpose. In the Fischetti study (1) the authors do not address the clinical applicability of the PFA-100 as a tool, but rather use it to investigate the phenomenon of platelet aggregation following coronary angioplasty. Fischetti, et al. demonstrate that ticlopidine’s effects on platelet aggregability are detected by the PFA-100. Similarly, the KottkeMarchant study (2) also examines platelet function in the setting of coronary angioplasty. Although this study is a closer evaluation of the PFA-100 itself, it does not examine the role of ticlopidine as a sole agent to decrease platelet aggregability. To view this study as an indictment of the PFA-100 in this regard is less than objective. The PFA-100 has not been specifically studied as a tool to assess clopidogrel-induced platelet dysfunction in an ambulatory setting. The vast preponderance of investigation, however, supports the use of the technology as a sensitive and specific tool for the detection of drug-induced platelet dysfunction, including that caused by the thienopyridines (3).