Christopher M. Viscomi

Intrathecal lipophilic opioids as adjuncts to surgical spinal anesthesia.

BACKGROUND AND OBJECTIVES Lipophilic opioids, especially fentanyl and sufentanil, are increasingly being administered intrathecally as adjuncts to spinal anesthesia. This review analyzes the efficacy of these opioids for subarachnoid anesthesia. METHODS Medline search of the literature from 1980 to the present and a survey of recent meeting abstracts are reviewed. RESULTS A significant number of citations regarding intrathecal lipophilic opioids as adjuncts to spinal anesthesia were found: 59 are cited in this review. Most clinical experience has been in obstetric surgery, but lipophilic spinal opioid administration is being used with greater frequency for other surgical procedures as well. The benefits include reduction of minimal alveolar concentration (MAC) when general anesthesia is combined with spinal anesthesia and enhancement of the quality of spinal anesthesia without prolongation of motor block. Intrathecal fentanyl and sufentanil allow clinicians to use smaller doses of spinal local anesthetic, yet still provide excellent anesthesia for surgical procedures. Furthermore, lipophilic opioid/local anesthetic combination permits more rapid motor recovery; short outpatient procedures are therefore more amenable to spinal anesthesia. Finally, the side-effect profiles of intrathecal lipophilic opioids are now well characterized and appear less troublesome than intrathecal morphine. CONCLUSIONS The anesthesia-enhancing properties and side-effect profile of lipophilic opioids administered intrathecally suggest significant roles for these agents as adjuncts to spinal anesthesia for obstetric and outpatient procedures.

Management of nonobstetric pain during pregnancy and lactation.

P ain management practitioners assist with the treatment of pain in a variety of settings. Despite the common occurrence of pain during pregnancy, major textbooks in both pain management and obstetrics lack any concentrated discussion of the topic. In this review, we discuss the potential for fetal toxicity or teratogenic effects of medications often used to treat pain syndromes, as well as the safety of these medications in the breast-feeding mother. We then present an approach to the diagnosis and treatment of several pain management challenges that may present during pregnancy.

Intrathecal fentanyl is superior to intravenous ondansetron for the prevention of perioperative nausea during cesarean delivery with spinal anesthesia.

This study compares intrathecal (IT) fentanyl with IV ondansetron for preventing intraoperative nausea and vomiting during cesarean deliveries performed with spinal anesthesia. Thirty healthy parturients presenting for elective cesarean delivery with standardized bupivacaine spinal anesthesia were randomized to receive 20 &mgr;g IT fentanyl (Group F) or 4 mg IV ondansetron (Group O) by using double-blinded methodology. At eight specific intervals during the surgery, a blinded observer questioned the patient about nausea (1 = nausea, 0 = no nausea), observed for the presence of retching or vomiting (1 = vomiting or retching, 0 = no vomiting or retching), and recorded a verbal pain score (0–10, 0 = no pain, 10 = worst pain imaginable). Cumulative nausea, vomiting, and pain scores were calculated as the sum of the eight measurements. Intraoperative nausea was decreased in the IT fentanyl group compared with the IV ondansetron group: the median (interquartile range) difference in nausea scores was 1 (1, 2), P = 0.03. The incidence of vomiting and treatment for vomiting was not different (P = 0.7). The IT fentanyl group had a lower cumulative perioperative pain score than the IV ondansetron group; the median difference in the cumulative pain score was 12 (8, 16) (P = 0.0007). The IT fentanyl group required less supplementary intraoperative analgesia. The median difference in the cumulative fentanyl dose was 100 (75, 100) &mgr;g fentanyl, (P = 0.0002). Implications Intrathecal fentanyl as part of a spinal anesthetic for cesarean delivery is superior to IV ondansetron for the prevention of intraoperative nausea. In addition, intrathecal fentanyl offers better perioperative pain control and is less expensive than ondansetron.

Duration of intrathecal labor analgesia: Early versus advanced labor

Early first-stage labor pain is primarily visceral in origin. Increasing pain intensity and transition to somatic nociceptive input characterizes late first- and second-stage labor pain. The effect of this change in nociceptive input on the duration of intrathecal labor analgesia has not been well studied. This prospective cohort observational study compares the duration of intrathecal labor analgesia after intrathecal injections made in early labor (3- to 5-cm cervical dilation) and those made in more advanced labor (7- to 10-cm cervical dilation). Forty-one parturients (18 in early labor and 23 in advanced labor) received intrathecal sufentanil (10 micro g) and bupivacaine (2.5 mg) as part of a combined spinal-epidural technique. Patients rated their pain using a 0-10 verbal pain scale prior to intrathecal injection and every 20 min thereafter. Duration of analgesia was defined as the lesser of time until the pain score exceeded 5 or until a request for supplemental epidural analgesia was made. The duration of spinal analgesia was significantly less when intrathecal injection was made in advanced labor (120 +/- 26 min) compared with early labor (163 +/- 57 min, P < 0.01). We conclude that cervical dilation and stage of labor significantly impact the effective duration of intrathecal sufentanil/bupivacaine labor analgesia. (Anesth Analg 1997;84:1108-12)

A Multicenter, Randomized, Blind Comparison of Amrinone with Milrinone After Elective Cardiac Surgery

Amrinone and milrinone are phosphodiesterase inhibitors with positive inotropic effects useful for the treatment of ventricular dysfunction after cardiac surgery.Forty-four patients undergoing elective cardiac surgery at four centers received either amrinone (n = 22) or milrinone (n = 22) in a randomized, blind fashion. Immediately after separation from cardiopulmonary bypass (CPB), two bolus doses of either amrinone 0.75 mg/kg or milrinone 25 [micro sign]g/kg were administered over 30 s, separated by 5 min. Hemodynamic measurements were recorded before each dose and at the end of the 10-min study. Both amrinone and milrinone increased the cardiac index (48% vs 52%, P = not significant [NS] for amrinone and milrinone, respectively). There was a small increase in mean arterial pressure (MAP) after amrinone administration (from 68 +/- 3 to 72 +/- 3 mm Hg at 10 min, P < 0.05) with no significant change in MAP after milrinone administration. Central venous pressure was significantly higher in the amrinone group at baseline and 5 min (12 vs 10 mm Hg and 11 vs 10 mm Hg, respectively; P < 0.05). Systemic and pulmonary vascular resistances decreased significantly and to a similar extent after either amrinone or milrinone administration. Phenylephrine was required in 11 of 22 patients receiving amrinone and in 11 of 22 patients receiving milrinone to maintain arterial blood pressure. The proportion of patients requiring an intravascular volume infusion (15 of 22 vs 17 of 22, P = NS) and the total fluid volume infused were similar (402 +/- 57 vs 350 +/- 49 mL, P = NS for amrinone and milrinone, respectively). Amrinone and milrinone seem to have similar hemodynamic effects after CPB, with the exception of blood pressure, although the need for vasopressor support of blood pressure did not differ. Selection between these two drugs may include nonhemodynamic considerations such as cost. Implications: Amrinone and milrinone are drugs that improve cardiac contraction. Their effects have never been directly compared in patients. We found that amrinone and milrinone produced similar hemodynamic effects in adult patients undergoing cardiac surgery. Choice between the two drugs can be based on nonhemodynamic considerations such as cost. (Anesth Analg 1998;86:683-90)

The effect of distance from injection site to the brainstem using spinal sufentanil.

Background and Objectives Intrathecal (IT) sufentanil is commonly used in parturients to provide rapid onset of labor analgesia without motor block. This practice, although widely used, has been associated with severe respiratory depression in some patients. The mechanism of this respiratory depression is unclear, however, rapid cephalad movement and interaction with parenteral opioids are 2 frequently cited explanations for this complication. Because this complication has occurred only in women with heights between 150 and 157 cm, we elected to study the effect of the distance from injection site to the cisterna magna (CM) on peak brainstem cerebrospinal fluid (CSF) concentrations. Methods Ten adult ewes were injected with IT sufentanil (0.3 μg/kg) at a mean distance of either 71 cm (65 to 78 cm) from the brainstem (pelvic group) or 37 cm (34 to 42 cm) from the brainstem (thoracic group). CSF was then sampled at 5-minute intervals from the CM. Results Measurable CM concentrations of sufentanil were noted in the brainstem at 20 and 25 minutes, respectively, for the thoracic and the pelvic groups. Peak sufentanil concentrations from the thoracic group were nearly 10-fold higher (0.553 ± 0.43 ng/mL) compared with the pelvic group (0.064 ± 0.002 ng/mL) when measured in the CM (P = .023). Conclusions Our results suggest that sufentanil migrates relatively large distances in the IT space. Injection site (distance from the brainstem) appears to be a prominent factor in determining brainstem concentrations and subsequent respiratory depression after spinal administration.

Nitroglycerin for relaxation to establish a fetal airway (EXIT procedure).

BACKGROUND: The ex utero intrapartum treatment (EXIT) procedure is a technique designed to establish an airway at the time of delivery in fetuses at risk of airway obstruction and requires maintenance of uterine relaxation to continue placental perfusion and prevent placental separation. We describe the use of intravenous nitroglycerin to maintain uterine relaxation during the EXIT procedure. CASE: A 17-year-old primigravida with a fetus known to have an anterior neck mass was admitted for a scheduled operative delivery at 38 weeks of gestation using a modified EXIT procedure. Anesthesia was administered with a combined spinal-epidural technique. Intravenous nitroglycerin was administered as a bolus and then as a continuous infusion to maintain uterine relaxation until evaluation of the neonatal airway was completed. CONCLUSION: Intravenous nitroglycerin is an effective agent for maintenance of uterine relaxation and placental perfusion during the EXIT procedure.

Spinal Anesthesia for Repair of Meningomyelocele in Neonates

The use of spinal anesthesia for meningomyelocele repair in neonates has received minimal attention.Spinal anesthesia may lessen the stress response to surgery and decrease postoperative respiratory complications. We therefore examined the efficacy of spinal anesthesia in 14 neonates requiring repair of lumbar or sacral meningomyelocele. All neonates were positioned prone with a small chest roll. Hyperbaric 0.5% tetracaine with epinephrine was injected into the caudal end of the meningomyelocele sac. If necessary, supplemental tetracaine was administered directly into the intrathecal space by the surgeon during the operation. Blood pressure, heart rate, and oxyhemoglobin saturation were measured throughout surgery. Neonates were monitored with transthoracic impedance apnea monitors, electrocardiogram (ECG), and pulse oximetry for 36 h after surgery. Spinal anesthesia was successful in all cases. Seven patients received one supplemental tetracaine injection; one patient received two supplemental injections. Arterial blood pressure decreased an average of 5 mm Hg with the largest decrease being 10 mm Hg. Two postoperative respiratory events occurred in the first 8 h after surgery. Both neonates had received intraoperative midazolam for sedation. Neurologic function was assessed pre- and postoperatively. Twelve patients had no change in neurologic function after surgery, while two infants demonstrated improved function. We conclude that spinal anesthesia can be safely used for meningomyelocele repair. (Anesth Analg 1995;81:492-5)

Ketamine as an adjuvant in lidocaine intravenous regional anesthesia: a randomized, double-blind, systemic control trial.

Background and Objectives: Ketamine delays and minimizes intraoperative tourniquet pain when added to lidocaine-based intravenous regional anesthesia (IVRA). It is unclear if adding ketamine to the IVRA injectate is more efficacious compared with systemic administration. This study compares intraoperative tourniquet pain, postoperative analgesia, and side effects of systemic versus IVRA ketamine during outpatient hand surgery. Methods: We conducted a randomized, double-blind, systemic control study of 40 patients undergoing hand surgery using lidocaine IVRA. In group IVRA, 0.1 mg/kg ketamine in 1 mL of normal saline was added to the IVRA lidocaine, and 1 mL of normal saline was administered via a peripheral IV line. In group systemic, 1 mL of normal saline was added to the IVRA syringe, and 0.1 mg/kg ketamine in 1 mL of normal saline was administered via a peripheral intravenous line. Ten minutes after proximal tourniquet inflation, the distal tourniquet was inflated, and the proximal tourniquet deflated. Tourniquet pain was measured every 10 mins. Need for intraoperative opioids was recorded. Recovery room pain scores, analgesic needs, and sedation scores were compared. Patients were contacted 24 hrs after surgery and reported their analgesic consumption, satisfaction scores, and the occurrence of any unpleasant psychologic effects. Results: Groups IVRA and systemic were comparable in demographic and surgical parameters. There were no differences between groups in intraoperative tourniquet pain scores, intraoperative fentanyl requirements, recovery room pain or sedation scores, postsurgical analgesic needs, or patient satisfaction scores. Conclusions: In comparison to systemic administration, there is no selective benefit to adding ketamine to the IVRA injectate.

Maternal fever, neonatal sepsis evaluation, and epidural labor analgesia.

Background and Objectives Numerous studies have found an association between epidural analgesia for labor and maternal fever (temperature ≥38°C). Maternal fever often results in treatment with maternal or neonatal antibiotics, neonatal sepsis evaluation, and increased costs. Methods Medline was used to identify literature regarding the association between epidural labor analgesia and maternal fever/neonatal sepsis. Studies examining thermoregulation during pregnancy and/or epidural analgesia were also reviewed. Results There appears to be a strong association between epidural labor analgesia and maternal fever. The link between epidural labor analgesia and neonatal sepsis evaluation is less clear. The incidence of confirmed neonatal sepsis does not increase with maternal epidural analgesia. Causes of the association between epidural labor analgesia and maternal fever include selection bias, altered thermoregulation, and increased shivering or decreased sweating with epidural analgesia. Conclusions Maternal epidural labor analgesia is associated with maternal fever and possibly increased neonatal sepsis evaluation. There is no proof the relationship is causal.