Richard N. Wissler

Association between Intraoperative Blood Transfusion and Mortality and Morbidity in Patients Undergoing Noncardiac Surgery

Background:The impact of intraoperative erythrocyte transfusion on outcomes of anemic patients undergoing noncardiac surgery has not been well characterized. The objective of this study was to examine the association between blood transfusion and mortality and morbidity in patients with severe anemia (hematocrit less than 30%) who are exposed to one or two units of erythrocytes intraoperatively. Methods:This was a retrospective analysis of the association of blood transfusion and 30-day mortality and 30-day morbidity in 10,100 patients undergoing general, vascular, or orthopedic surgery. We estimated separate multivariate logistic regression models for 30-day mortality and for 30-day complications. Results:Intraoperative blood transfusion was associated with an increased risk of death (odds ratio [OR], 1.29; 95% CI, 1.03–1.62). Patients receiving an intraoperative transfusion were more likely to have pulmonary, septic, wound, or thromboembolic complications, compared with patients not receiving an intraoperative transfusion. Compared with patients who were not transfused, patients receiving one or two units of erythrocytes were more likely to have pulmonary complications (OR, 1.76; 95% CI, 1.48–2.09), sepsis (OR, 1.43; 95% CI, 1.21–1.68), thromboembolic complications (OR, 1.77; 95% CI, 1.32–2.38), and wound complications (OR, 1.87; 95% CI, 1.47–2.37). Conclusions:Intraoperative blood transfusion is associated with a higher risk of mortality and morbidity in surgical patients with severe anemia. It is unknown whether this association is due to the adverse effects of blood transfusion or is, instead, the result of increased blood loss in the patients receiving blood.

Perioperative outcomes among patients with the modified metabolic syndrome who are undergoing noncardiac surgery.

Background:Previous studies have demonstrated that obesity is paradoxically associated with a lower risk of mortality after noncardiac surgery. This study will determine the impact of the modified metabolic syndrome (defined as the presence of obesity, hypertension, and diabetes) on perioperative outcomes. Methods:This study is based on data from 310,208 patients in the American College of Surgeons National Surgical Quality Improvement Program database. We estimated separate multivariate logistic regression models for 30-day mortality and for 30-day complications. Results:Patients with the modified metabolic syndrome who are super obese had a 2-fold increased risk of death (adjusted odds ratio [AOR] 1.99; 95% CI 1.41–2.80). As stratified by body mass index, patients with the modified metabolic syndrome had a 2- to 2.5-fold higher risk of cardiac adverse events (CAE) compared with normal-weight patients: obese (AOR 1.70; 95% CI 1.40–2.07), morbidly obese (AOR 2.01; 95% CI 1.48–2.73), and super obese (AOR 2.66; 95% CI 1.68–4.19). In addition, the risk of acute kidney injury (AKI) was 3- to 7-fold higher in these patients: obese (AOR 3.30; 95% CI 2.75–3.94), morbidly obese (AOR 5.01; 95% CI 3.87–6.49), and super obese (AOR 7.29; 95% CI 5.27–10.1). Conclusion:Patients with the modified metabolic syndrome undergoing noncardiac surgery are at substantially higher risk of complications compared with patients of normal weight.

Densities of dextrose-free intrathecal local anesthetics, opioids, and combinations measured at 37 degrees C.

Dextrose-free anesthetic medications are commonly used to provide subarachnoid anesthesia and analgesia. Hypobaricity has been proposed as a mechanism to explain postural effects on the extent of sensory block produced by these drugs. Densities of dextrose-free solutions of local anesthetics and opioids, and commonly used anesthetic/opioid mixtures were determined at 37.00 degrees C for comparison with the density of human cerebrospinal fluid (CSF). Measurements accurate to 0.00001 g/mL were performed using a mechanical oscillation resonance frequency density meter. All undiluted solutions tested are hypobaric relative to human lumbar CSF with the exception of lidocaine 1.5% and 2.0% with epinephrine 1:200,000. All mixtures of local anesthetics and opioids tested are hypobaric. We observed good agreement between measured densities and calculated weighted average densities of anesthetic mixtures. While the influence of baricity on the clinical effects of dextrose-free intrathecal anesthetics remains controversial, attempts to attribute postural effects to the baricity of these drugs requires establishment of accurate density values. These density data may facilitate elucidation of the mechanisms underlying the behavior of dextrose-free intrathecal anesthetics. (Anesth Analg 1997;84:95-9)

Racial Differences in the Use of Epidural Analgesia for Labor

Background:There is strong evidence that pain is undertreated in black and Hispanic patients. The association between race and ethnicity and the use of epidural analgesia for labor is not well described. Methods:Using the New York State Perinatal Database, the authors examined whether race and ethnicity were associated with the likelihood of receiving epidural analgesia for labor after adjusting for clinical characteristics, demographics, insurance coverage, and provider effect. This retrospective cohort study was based on 81,883 women admitted for childbirth between 1998 and 2003. Results:Overall, 38.3% of the patients received epidural analgesia for labor. After adjusting for clinical risk factors, socioeconomic status, and provider fixed effects, Hispanic and black patients were less likely than non-Hispanic white patients to receive epidural analgesia: The adjusted odds ratio was 0.85 (95% CI, 0.78–0.93) for white/Hispanic and 0.78 (0.74–0.83) for blacks compared with non-Hispanic whites. Compared with patients with private insurance, patients without insurance were least likely to receive epidural analgesia (adjusted odds ratio, 0.76; 95% CI, 0.64–0.89). Black patients with private insurance had similar rates of epidural use to white/non-Hispanic patients without insurance coverage: The adjusted odds ratio was 0.66 (95% CI, 0.53–0.82) for white/non-Hispanic patients without insurance versus 0.69 (0.57–0.85) for black patients with private insurance. Conclusion:Black and Hispanic women in labor are less likely than non-Hispanic white women to receive epidural analgesia. These differences remain after accounting for differences in insurance coverage, provider practice, and clinical characteristics.

Variation of blood transfusion in patients undergoing major noncardiac surgery.

Objective: To examine the hospital variability in use of red blood cells (RBCs), fresh-frozen plasma (FFP), and platelet transfusions in patients undergoing major noncardiac surgery. Background: Blood transfusion is commonly used in surgical procedures in the United States. Little is known about the hospital variability in perioperative transfusion rates for noncardiac surgery. Methods: We used the University HealthSystem Consortium database (2006–2010) to examine hospital variability in use of allogeneic RBC, FFP, and platelet transfusions in patients undergoing major noncardiac surgery. We used regression-based techniques to quantify the variability in hospital transfusion practices and to study the association between hospital characteristics and the likelihood of transfusion. Results: After adjusting for patient risk factors, hospital transfusion rates varied widely for patients undergoing total hip replacement (THR), colectomy, and pancreaticoduodenectomy. Compared with patients undergoing THR in average-transfusion hospitals, patients treated in high-transfusion hospitals have a greater than twofold higher odds of being transfused with RBCs [adjusted odds ratio (AOR) = 2.41; 95% confidence interval (CI), 1.89–3.09], FFP (AOR = 2.81; 95% CI, 2.02–3.91), and platelets (AOR = 2.52; 95% CI, 1.95–3.25), whereas patients in low-transfusion hospitals have an approximately 50% lower odds of receiving RBCs (AOR = 0.45; 95% CI, 0.35–0.57), FFP (AOR = 0.37; 95% CI, 0.27–0.51), and platelets (AOR = 0.42; 95% CI, 0.29–0.62). Similar results were obtained for colectomy and pancreaticoduodenectomy. Conclusions: There was dramatic hospital variability in perioperative transfusion rates among patients undergoing major noncardiac surgery at academic medical centers. In light of the potential complications of transfusion therapy, reducing this variability in hospital transfusion practices may result in improved surgical outcomes.

A Randomized, Double-masked, Multicenter Comparison of the Safety of Continuous Intrathecal Labor Analgesia Using a 28-Gauge Catheter versus Continuous Epidural Labor Analgesia

Background:Continuous intrathecal labor analgesia produces rapid analgesia or anesthesia and allows substantial flexibility in medication choice. The US Food and Drug Administration, in 1992, removed intrathecal microcatheters (27–32 gauge) from clinical use after reports of neurologic injury in nonobstetric patients. This study examined the safety and efficacy of a 28-gauge intrathecal catheter for labor analgesia in a prospective, randomized, multicenter trial. Methods:Laboring patients were randomly assigned to continuous intrathecal analgesia with a 28-gauge catheter (n = 329) or continuous epidural analgesia with a 20-gauge catheter (n = 100), using bupivacaine and sufentanil. The primary outcome was the incidence of neurologic complications, as determined by masked neurologic examinations at 24 and 48 h postpartum, plus telephone follow-up at 7–10 and 30 days after delivery. The secondary outcomes included adequacy of labor analgesia, maternal satisfaction, and neonatal status. Results:No patient had a permanent neurologic change. The continuous intrathecal analgesia patients had better early analgesia, less motor blockade, more pruritus, and higher maternal satisfaction with pain relief at 24 h postpartum. The intrathecal catheter was significantly more difficult to remove. There were no significant differences between the two groups in neonatal status, post–dural puncture headache, hemodynamic stability, or obstetric outcomes. Conclusions:Providing intrathecal labor analgesia with sufentanil and bupivacaine via a 28-gauge catheter has an incidence of neurologic complication less than 1%, and produces better initial pain relief and higher maternal satisfaction, but is associated with more technical difficulties and catheter failures compared with epidural analgesia.

Intrathecal Hypobaric Versus Hyperbaric Bupivacaine with Morphine for Cesarean Section

Both hyper-and hypobaric solutions of bupivacaine are often combined with morphine to provide subarachnoid anesthesia for cesarean section. Differences in the baricity of subarachnoid solutions influence the intrathecal distribution of anesthetic drugs and would be expected to influence measurable clinical variables. We compared the effects of hyper- and hypobaric subarachnoid bupivacaine with morphine to determine whether one has significant advantages with regard to intraoperative anesthesia and postoperative analgesia in term parturients undergoing elective cesarean section. Thirty parturients were randomized to receive either hyper- or hypobaric bupivacaine (15 mg) with morphine sulfate (0.2 mg). Intraoperative outcomes compared included extent of sensory block, quality of anesthesia, and side effects. Postoperative outcomes, including pain visual analog scale scores, systemic analgesic requirements, and side effects, were monitored for 48 h. Sedation effects were quantified and compared using Trieger and digit-symbol substitution tests. We detected no differences in sensory or motor block, quality of anesthesia, quality of postoperative analgesia, incidence of side effects, or psychometric scores. Both preparations provide highly satisfactory anesthesia for cesarean section and effective postoperative analgesia. Implications: Dextrose alters the density of intrathecal bupivacaine solutions and is thought to influence subarachnoid distribution of the drug. We randomized parturients undergoing cesarean section to one of two often used spinal bupivacaine preparations, hypobaric and hyperbaric. We detected no differences in clinical outcomes between groups. (Anesth Analg 1998;87:336-40)

General anesthesia with remifentanil for Cesarean section in a parturient with an acoustic neuroma.

PurposeTo describe the anesthetic management of a parturient with a large acoustic neuroma undergoing general anesthesia with remifentanil for Cesarean section.Clinical featuresA near-term parturient presented with a large intracranial mass. Cesarean section under general anesthesia was elected one week prior to craniotomy for tumour resection. Remifentanil infusion, 0.2–1.0 μg · kg−1 · min−1, was used from induction to emergence of general anesthesia. The neonate was born seven minutes after the remifentanil infusion was started. She had normal umbilical cord pH and her Apgar scores were 7 and 8, at one and five minutes respectively. Although the neonate received supplemental oxygen, she did not require naloxone. Both mother and neonate made an uneventful recovery.ConclusionRemifentanil was effective in producing stable hemodynamic conditions, without severe neonatal respiratory depression, during induction and maintenance of general anesthesia for a Cesarean delivery in a parturient with a large intracranial tumour.AbstractObjectifDécrire la conduite de l’anesthésie générale avec le rémifentanil pour une césarienne chez une patiente enceinte ayant un neurinome acoustique.Aspects cliniquesUne femme enceinte s’est présentée avec une volumineuse masse intracrânienne quelques semaines avant terme. Une césarienne sous anesthésie générale a été planifiée une semaine avant de procéder à la résection de la tumeur intracrânienne. Le rémifentanil en perfusion intraveineuse a été utilisé de l’induction à l’émergence, à des doses variant de 0.2–1.0 μg · kg−1 · min−1. L’enfant est né après sept minutes de perfusion de rémifentanil. Les gaz du cordon étaient normaux et les Apgar à une et cinq minutes étaient respectivement 7 et 8. Malgré l’apport temporaire d’oxygène, le nouveau-né n’a pas eu besoin de naloxone. La mère et l’enfant ont eu une convalescence sans complication.ConclusionLe rémifentanil a permis des conditions hémodynamiques stables, sans produire de dépression respiratoire significative chez le nouveau-né, pendant l’induction et la maintenance de l’anesthésie générale pour une césarienne chez une patiente avec une volumineuse tumeur intracrânienne.

Maternal posture influences the extent of sensory block produced by intrathecal dextrose-free bupivacaine with fentanyl for labor analgesia

The cephalad extent of sensory block produced by intrathecal (IT) dextrose-free local anesthetics and opioids has been reported to be quite variable. Most reports describing the effects of IT analgesics do not control for patient posture. Because these medications are hypobaric relative to cerebrospinal fluid (CSF), parturients in a sitting position may develop greater cephalad extents of sensory block than those in a lateral position during IT injection. Parturients in labor were randomized to sitting or lateral position during IT administration of dextrose-free bupivacaine 0.25% with fentanyl 0.005%. Extent of sensory block was evaluated at intervals thereafter. Free flow of CSF was obtained in 20 parturients. Those in a sitting position during IT injection had significantly higher maximal cephalad extent of block than those in a lateral position (mean +/- SD, T-3.1 +/- 2.9 vs T-6.3 +/- 3.4, P = 0.036). Mean cephalad extent of block was greater in the sitting group at 20 and 30 min. When sensory block asymmetry was observed, the extent of block was greater on the nondependent side. Posture during IT injection of this dextrose-free analgesic combination affects extent of sensory block in laboring parturients. (Anesth Analg 1996;83:1229-33)

The effects of needle bevel orientation during epidural catheter insertion in laboring parturients.

UNLABELLED Lateral needle bevel orientation during identification of the epidural space has been recommended to reduce the risk of postdural puncture headache (PDPH). Rotation to cephalad or caudad orientation before catheter insertion is assumed necessary for analgesic success. We prospectively compared the effects of catheter insertion through lateral- and cephalad-oriented Tuohy needle bevels in laboring parturients. Anesthesiology residents were randomized to identify the epidural space with bevels oriented cephalad or lateral. Catheters were inserted without needle rotation. Outcomes compared included ease of insertion, analgesic effectiveness, and complications. We evaluated 534 catheter insertions in 500 parturients. Initial catheter insertion produced satisfactory analgesia in 80.2% of the lateral group versus 91.1% of the cephalad group (P < 0.001). Resistance preventing catheter insertion accounted for the difference. There were no differences in i.v. cannulation (5.8% vs 5.1%), dural puncture (3.8% vs 2.0%), PDPH (0.4% vs 0.7%), or asymmetric block (31% vs 27%). There was a slightly higher rate of paresthesias in the lateral group (31% vs 23%; P = 0.048). In 78% of parturients experiencing both paresthesias and asymmetric block, the side of the paresthesia and greater extent of block were the same. Analgesic effectiveness, as measured by using a visual analog scale, was not different between the groups. IMPLICATIONS Two methods of epidural catheter insertion were compared in laboring parturients. Catheter insertion with the needle orifice oriented cephalad was associated with the greatest initial success and the fewest complications.