Engy T. Said

Continuous Transversus Abdominis Plane Nerve Blocks: Does Varying Local Anesthetic Delivery Method-automatic Repeated Bolus Versus Continuous Basal Infusion-influence the Extent of Sensation to Cold?: A Randomized, Triple-masked, Crossover Study in Volunteers.

BACKGROUND: It remains unknown whether continuous or scheduled intermittent bolus local anesthetic administration is preferable for transversus abdominis plane (TAP) catheters. We therefore tested the hypothesis that when using TAP catheters, providing local anesthetic in repeated bolus doses increases the cephalad-caudad cutaneous effects compared with a basal-only infusion. METHODS: Bilateral TAP catheters (posterior approach) were inserted in 24 healthy volunteers followed by ropivacaine 2 mg/mL administration for a total of 6 hours. The right side was randomly assigned to either a basal infusion (8 mL/h) or bolus doses (24 mL administered every 3 hours for a total of 2 bolus doses) in a double-masked manner. The left side received the alternate treatment. The primary end point was the extent of sensory deficit as measured by cool roller along the axillary line at hour 6 (6 hours after the local anesthetic administration was initiated). Secondary end points included the extent of sensory deficit as measured by cool roller and Von Frey filaments along the axillary line and along a transverse line at the level of the anterior superior iliac spine at hours 0 to 6. RESULTS: Although there were statistically significant differences between treatments within the earlier part of the administration period, by hour 6 the difference in extent of sensory deficit to cold failed to reach statistical significance along the axillary line (mean = 0.9 cm; SD = 6.8; 95% confidence interval –2.0 to 3.8; P = .515) and transverse line (mean = 2.5 cm; SD = 10.1; 95% confidence interval –1.8 to 6.8; P = .244). Although the difference between treatments was statistically significant at various early time points for the horizontal, vertical, and estimated area measurements of both cold and mechanical pressure sensory deficits, no comparison remained statistically significant by hour 6. CONCLUSIONS: No evidence was found in this study involving healthy volunteers to support the hypothesis that changing the local anesthetic administration technique (continuous basal versus hourly bolus) when using ropivacaine 0.2% and TAP catheters at 8 mL/h and 24 mL every 3 hours significantly influences the cutaneous effects after 6 hours of administration. Additional research is required to determine whether changing variables (eg, local anesthetic concentration, basal infusion rate, bolus dose volume, and/or interval) would provide different results.

Ultrasound-Guided Percutaneous Peripheral Nerve Stimulation: Neuromodulation of the Femoral Nerve for Postoperative Analgesia Following Ambulatory Anterior Cruciate Ligament Reconstruction: A Proof of Concept Study: FEMORAL NEUROMODULATION AND POSTOP PAIN

The purpose of this prospective proof of concept study was to investigate the feasibility of using percutaneous peripheral nerve stimulation of the femoral nerve to treat pain in the immediate postoperative period following ambulatory anterior cruciate ligament reconstruction with a patellar autograft.

A Feasibility Study of Percutaneous Peripheral Nerve Stimulation for the Treatment of Postoperative Pain Following Total Knee Arthroplasty: PERCUTANEOUS PNS FOR POSTOPERATIVE PAIN

The objective of the present feasibility study was to investigate the use of a new treatment modality—percutaneous peripheral nerve stimulation (PNS)—in controlling the often severe and long‐lasting pain following total knee arthroplasty (TKA).

Proximal Versus Distal Continuous Adductor Canal Blocks: Does Varying Perineural Catheter Location Influence Analgesia? A Randomized, Subject-Masked, Controlled Clinical Trial

BACKGROUND: A continuous adductor canal block provides analgesia after surgical procedures of the knee. Recent neuroanatomic descriptions of the thigh and knee led us to speculate that local anesthetic deposited in the distal thigh close to the adductor hiatus would provide superior analgesia compared to a more proximal catheter location. We therefore tested the hypothesis that during a continuous adductor canal nerve block, postoperative analgesia would be improved by placing the perineural catheter tip 2–3 cm cephalad to where the femoral artery descends posteriorly to the adductor hiatus (distal location) compared to a more proximal location at the midpoint between the anterior superior iliac spine and the superior border of the patella (proximal location). METHODS: Preoperatively, subjects undergoing total knee arthroplasty received an ultrasound-guided perineural catheter inserted either in the proximal or distal location within the adductor canal in a randomized, subject-masked fashion. Subjects received a single injection of lidocaine 2% via the catheter preoperatively, followed by an infusion of ropivacaine 0.2% (8 mL/h basal, 4 mL bolus, 30 minutes lockout) for the study duration. After joint closure, the surgeon infiltrated the entire joint using 30 mL of ropivacaine (0.5%), ketorolac (30 mg), epinephrine (5 &mgr;g/mL), and tranexamic acid (2 g). The primary end point was the median level of pain as measured on a numeric rating scale (NRS) during the time period of 8:00 AM to 12:00 PM the day after surgery. RESULTS: For the primary end point, the NRS of subjects with a catheter inserted at the proximal location (n = 24) was a median (10th, 25th–75th, 90th quartiles) of 0.5 (0.0, 0.0–3.2, 5.0) vs 3.0 (0.0, 2.0–5.4, 7.8) for subjects with a catheter inserted in the distal location (n = 26; P = .011). Median and maximum NRSs were lower in the proximal group at all other time points, but these differences did not reach statistical significance. There were no clinically relevant or statistically significant differences between the treatment groups for any other secondary end point, including opioid consumption and ambulation distance. CONCLUSIONS: For continuous adductor canal blocks accompanied by intraoperative periarticular local anesthetic infiltration, analgesia the day after knee arthroplasty is improved with a catheter inserted at the level of the midpoint between the anterior superior iliac spine and the superior border of the patella compared with a more distal insertion closer to the adductor hiatus.

Bi-level Positive Airway Pressure, Decreased Sensorium, Aspiration, and Capnography

While noninvasive positive pressure ventilation (NIPPV) has several advantages in comparison to invasive modes of ventilation, there are cases where the risks associated with NIPPV far outweigh those benefits. In this chapter we discuss the advantages and disadvantages of the various modes of NIPPV, the pathophysiology of aspiration, as well as run a comparison between devices used to confirm tracheal intubation during cardiac arrest.

Postoperative Monocular Vision Loss

Postoperative visual loss is a rare but debilitating condition. This chapter discusses the pathophysiology of perioperative visual loss and reviews means of minimizing risk. The differential diagnosis for visual loss is discussed. In addition, we highlight similarities and differences between multiple ocular vascular conditions.

Obstructive Sleep Apnea and Dead in Bed

Obstructive sleep apnea (OSA) patients are at increased risk for adverse perioperative outcomes, and for this reason, guidelines have been developed in effort to reduce, if not eliminate, OSA-related perioperative morbidity and mortality. In this chapter, we discuss the anatomy and pathophysiology of OSA, the clinical determinants of OSA severity, as well as the guidelines for monitoring these patients during the perioperative period.