Effects of Adding Intrathecal Epinephrine to Spinal Anesthesia on Anesthesia-Related Cesarean Delivery Outcomes: Should We Reconsider Its Use?

BACKGROUND:  Intrathecal epinephrine is used to increase the duration of spinal anesthesia for amenable surgical procedures anticipated to require additional time; however, in the ambulatory setting, it is associated with a prolonged time to post-anesthesia care unit (PACU) discharge. The current study's authors hypothesized that adding intrathecal epinephrine to spinal anesthesia for cesarean delivery would be associated with a dose-dependent prolonged post-anesthesia unit length of stay. METHODS: A single-center, retrospective study of patients undergoing repeat cesarean delivery under spinal anesthesia from 2011 to 2015 was conducted. Patients received spinal bupivacaine 12 mg, morphine 150 mcg, and fentanyl 15 mcg with no-epinephrine, 100 mcg, or 200 mcg of epinephrine. The primary outcome was recovery room length of stay. Secondary outcomes were surgical duration, intraoperative vasopressor use, perioperative opioids, and antiemetic use. RESULTS:  Data were analyzed for 1,362 patients. Median recovery room stay was 123 min (interquartile range, 100 to 150) and was not different among groups. More women receiving epinephrine 200 mcg had ≥2 prior cesarean deliveries compared with no-epinephrine or 100 mcg. No significant differences in surgical duration or intraoperative opioids were identified among the groups. Median intraoperative vasopressor use was increased by 225 mcg of phenylephrine equivalents (99% CI, 25 mcg to 430 mcg) in the 100 mcg group and 250 mcg of phenylephrine equivalents in the 200 mcg group (99% CI, 75 mcg to 500 mcg) compared to no-epinephrine (P<0.001). Recovery room antiemetic and opioid analgesic administration were not different among groups. CONCLUSIONS:  Based on the results of this study, the addition of intrathecal epinephrine for women undergoing cesarean delivery increases intraoperative vasopressor use but does not prolong PACU length of stay, reduce intraoperative opioids, or increase antiemetic requirements postoperatively. The current study also demonstrated that surgical duration times were not different among the no-epinephrine, 100 mcg, and 200 mcg epinephrine groups.

Ultrasound-guided genicular nerve blocks following total knee arthroplasty: a randomized, double-blind, placebo-controlled trial.

INTRODUCTION: Local anesthetic blockade of the genicular nerves, known targets of radiofrequency ablative techniques for knee pain, has not previously been studied in a randomized controlled trial evaluating acute pain after knee arthroplasty. We hypothesized that genicular nerve blockade added to an existing block regimen in total knee arthroplasty would result in a reduction in 24 hours opioid consumption. METHODS: Patients (American Society of Anesthesiologists 1-3, aged 18-85 years) undergoing primary total knee arthroplasty were randomized to receive single-injection nerve blocks of the superolateral, superomedial, and inferomedial genicular nerves with injectate (15 mL 0.25% bupivacaine and 2 mg dexamethasone or 15 mL saline placebo). All subjects received a standard oral analgesic regimen, spinal anesthetic with 12.5 mg isobaric bupivacaine, infiltration between the popliteal artery and capsule of the knee with 0.2% ropivacaine, and postoperative adductor canal perineural infusion with 0.2% ropivacaine. The primary outcome was 24 hours opioid consumption (measured in morphine milliequivalents). RESULTS: Forty (40) subjects were enrolled. Opioid consumption at 24 hours was significantly lower in the BLOCK group compared with the SHAM group (23±20 vs 58±35, p<0.001), and this difference remained significant at 48 hours (50±40 vs 98±56, p=0.004). Pain scores were reduced in the BLOCK group at time 6 hours (2.6±1.9 vs 4.3±2.2, p=0.012), but were otherwise similar at remaining time points. Patient satisfaction at 24 hours and 20 m walk test times were similar between groups. DISCUSSION: Genicular nerve blockade was associated with a reduction in opioid consumption at 24 hours in primary total knee arthroplasty patients. TRIAL REGISTRATION NUMBER: NCT03706313.

Femoral artery block (FAB) attenuates thigh tourniquet-induced hypertension: a prospective randomized, double-blind, placebo-controlled trial.

INTRODUCTION: Prolonged tourniquet inflation during surgery frequently leads to tourniquet hypertension (TH), which is thought to arise from compression of A-δ fibers leading to sympathetically mediated C fiber activation. In the lower extremity, C fibers and other sympathetic nerve fibers are carried along the femoral artery. We hypothesized that blockade of these fibers at the femoral artery would decrease the incidence of TH. METHODS: Thirty American Society of Anesthesia 1-3 patients aged 18-75 undergoing total ankle arthroplasty were randomized to receive 15 mL of injectate (mepivacaine 1.5% or saline placebo) at the anteromedial aspect of the common femoral artery at the level of the inguinal crease under ultrasound guidance. Both groups received preoperative popliteal sciatic and saphenous nerve blocks for analgesia and a standardized general anesthetic. Esmolol was administered if systolic blood pressure rose >30% above baseline. Incidence of TH was the primary outcome. RESULTS: TH was present in 93.3% of sham patients versus 33.3% of block patients. Mean systolic pressure at 120 min and 150 min of tourniquet time was significantly higher in the sham group compared with the block group. Esmolol requirement (95.3+107.6 v 8.0+14.2, p=<0.001) was also significantly higher in the sham group. No differences were noted in pain scores or opioid consumption, and no patient experienced sensory or motor block of the femoral nerve. DISCUSSION: Under these experimental conditions, injection of local anesthetic around the femoral artery reduced the incidence of TH and intraoperative esmolol requirement. TRIAL REGISTRATION NUMBER: www.clinicaltrials.gov (NCT03390426; December 28, 2017).

Pressure monitoring: The evidence so far.

Nerve injury is a relatively rare but devastating complication of peripheral nerve blockade (PNB). Monitoring injection pressure during PNB is one method advocated to prevent injury by detecting needle tip placement in a noncompliant position (intraneural or abutting the epineurium). Animal studies show that gross neural damage and clinical injury are associated with injection pressures exceeding 15-20 psi. In contrast, pressures <15 psi are associated with an extraneural needle tip position and no histologic or clinical injury. Injection pressure monitoring has been shown to prevent injection against the brachial plexus roots or femoral nerve during peripheral nerve block. Multiple methods are available to monitor injection pressure, and most of them are inexpensive and easy to use. Large-scale registry database or pragmatic trials are indicated to show that injection pressure monitoring reduces injury in a patient setting.

Perioperative Clinical Considerations in a Patient With Carotid Agenesis: A Case Report.

An 86-year-old female with previously diagnosed congenitally absent right internal carotid artery presented for total shoulder arthroplasty. Bedside ultrasonography confirmed the anomaly and identified several arterial collateral vessels. No aberrant vessels were seen traversing the brachial plexus. The patient received brachial plexus blockade and general anesthesia for the procedure. Carotid agenesis is associated with increased prevalence of intracranial aneurysm. Patients are often asymptomatic due to adequate blood supply from collateral vessels. Ultrasonography for brachial plexus blockade or central line access may yield initial diagnosis or confirm a preexisting anomaly that has anesthetic implications. These prospects encourage vigilance in perioperative imaging.

Early Bird Gets the Flu: What Should Be Done About Waning Intraseasonal Immunity Against Seasonal Influenza?

Recently published studies highlight the growing evidence for waning immunity within a single influenza season among vaccinated individuals. However, the public health efforts to increase vaccination coverage has resulted in earlier administration of vaccines. We find this approach to be suboptimal, as the benefits of early vaccination could be lost during peak months of influenza activity. Immunity generated by influenza vaccines is a complex scientific issue with many contributing factors. We advocate for a nuanced approach to the seasonal vaccine program- one that considers duration of immunity as much as it considers coverage. As we strive for higher rates of vaccination, we must also improve the efficacy of the vaccine and the public health programs that are responsible for distributing and administering the vaccine.