Biomedical subjects

Jerry D Vloka

Publications and source records attributed to Jerry D Vloka.

8 recordsLinked to original sources

PubMed2005

Neurologic complication after anterior sciatic nerve block.

The lack of reported complications related to lower extremity peripheral nerve blocks (PNBs) may be related to the relatively infrequent application of these techniques and to the fact that most such events go unpublished. Our current understanding of the factors that lead to neurologic complications after PNBs is limited. This is partly the result of our inability to conduct meaningful retrospective studies because of a lack of standard and objective monitoring and documentation procedures for PNBs. We report a case of permanent injury to the sciatic nerve after sciatic nerve block through the anterior approach and discuss mechanisms that may have led to the injury. Intraneural injection and nerve injury can occur in the absence of pain on injection and it may be heralded by high injection pressure (resistance).

Anesthetics, Local↗

PubMed2005

Peripheral nerve blocks result in superior recovery profile compared with general anesthesia in outpatient knee arthroscopy.

It has been suggested that use of peripheral nerve blocks (PNBs) may have some potential benefits in the outpatient setting. There have been no studies specifically comparing PNBs performed with short-acting local anesthetics with general anesthesia (GA) in patients undergoing outpatient knee surgery. We hypothesized that a combination of lumbar plexus and sciatic blocks using a short-acting local anesthetic will result in shorter time-to-discharge-home as compared with GA. Patients scheduled to undergo knee arthroscopy were randomized to receive a GA (midazolam, fentanyl, propofol, N(2)O/O(2)/desflurane via laryngeal mask airway) or lumbar plexus/sciatic block (PNBs; 2-chloroprocaine). Patients given GA also received an intraarticular injection of 20 mL 0.25% bupivacaine for postoperative pain control. Patients in the PNB group were given midazolam (up to 4 mg) and alfentanil (500-750 microg) before block placement and propofol 30-50 microg . kg(-1) . min(-1) for intraoperative sedation. Relevant perioperative times, postanesthesia care unit bypass rate, severity of pain, and incidence of complications were compared between the two groups. Fifty patients were enrolled in the study; 25 patients each received GA or PNBs. Total operating room time did not differ significantly between the 2 groups (97 +/- 37 versus 91 +/- 42 min). Seventy-two percent of patients receiving PNB met criteria enabling them to bypass Phase I postanesthesia care unit compared with only 24% of those receiving GA (P < 0.002). Time to meet criteria for discharge home (home readiness) and time to actual discharge were significantly shorter for patients given PNBs than for patients given GA (131 +/- 62 versus 205 +/- 94 and 162 +/- 71 versus 226 +/- 96, respectively). Under the conditions of our study, the combination of lumbar plexus and sciatic blocks with 2-chloroprocaine 3% was associated with a superior recovery profile compared with GA in patients having outpatient knee arthroscopy.

Adolescent↗

PubMed2004

Electrical nerve localization: effects of cutaneous electrode placement and duration of the stimulus on motor response.

BACKGROUND: Recommendations regarding the technical aspects of nerve stimulator-assisted nerve localization are conflicting. The objectives of this study were to determine whether the placement of the cutaneous electrode affects nerve stimulation and to determine the duration and intensity of an electrical stimulus that allows nerve stimulation with minimal discomfort. METHODS: Ten healthy volunteers underwent an interscalene and a femoral nerve block. After obtaining a clearly visible motor response of the biceps (interscalene) and quadriceps (femoral) muscles at the minimal current (0.1 ms, 2 Hz), the position of the cutaneous electrode was varied. Next, the duration of the stimulating current was set at 0.05, 0.1, 0.3, 0.5, or 1.0 ms, in random order. Intensity of the motor response and discomfort on stimulation were recorded. RESULTS: The minimal current at which a visible motor response was obtained was 0.32 +/- 0.1 mA (0.23-0.38 mA) for the inter-scalene block and 0.29 +/- 0.1 mA (0.15-0.4 mA) for the femoral block. Changing the position of the return electrodes did not result in any change in the grade of the motor response or in the current required to maintain it. Currents of longer duration caused discomfort and more forceful contraction at a lower current intensity as compared with currents of shorter duration (P < 0.01). When the current was adjusted to maintain the same visible motor response, there was no significant discomfort among studied current durations. CONCLUSION: Site of placement of the cutaneous electrode is not important when constant current nerve stimulators are used during nerve localization in regional anesthesia. There is an inverse relation between the current required to obtain a visible motor response and current duration. Selecting a current duration between 0.05 and 1.0 ms to specifically stimulate sensory or motor components of a mixed nerve does not seem to be important in clinical practice.

Adult↗

PubMed2004

A comparison of infraclavicular nerve block versus general anesthesia for hand and wrist day-case surgeries.

BACKGROUND: General anesthesia (GA) and brachial plexus block have been used successfully for surgery on the upper extremities. Controversy exists as to which method is more suitable in outpatients undergoing hand and wrist surgery. The authors hypothesized that infraclavicular brachial plexus block (INB) performed with a short-acting local anesthetic would result in shorter time to discharge home as compared with "fast-track" GA. METHODS: After obtaining written informed consent, 52 patients (aged 18-65 yr, American Society of Anesthesiologists physical status I-III) were randomly assigned to receive either an INB or GA under standardized protocols (INB = 3% 2-chloroprocaine + HCO3 + epinephrine 1:300000, followed by propofol sedation; GA = 12.5 mg dolasetron, propofol induction, followed by laryngeal mask airway insertion and desflurane for maintenance; 0.25% bupivacaine for wound infiltration). At the conclusion of the procedure, nurses blinded to the study goals and the anesthetic technique used a modified Aldrete score to decide whether patients could bypass the postanesthesia care unit. Additional data were collected regarding time to postoperative pain, ambulation, home readiness, and incidence of adverse events. RESULTS: More patients in the INB group (79%) met the criteria to bypass the postanesthesia care unit compared with patients in the GA group (25%; P < 0.001). Compared with patients in the GA group, fewer patients in the INB group had pain (visual analog scale score > 3) on arrival to the postanesthesia care unit (3% vs. 43%; P < 0.001). None of the patients in the INB group requested treatment for pain while in the hospital, compared with 48% of patients in the GA group (P < 0.001). Patients in the INB group were able to ambulate earlier (82 +/- 41 min) compared with those in the GA group (145 +/- 70 min; P < 0.001). Time to home readiness and discharge times were shorter for patients in the INB group (100 +/- 44 and 121 +/- 37 min) compared with those in the GA group (203 +/- 91 and 218 +/- 93 min; P < 0.001). Adverse events (e.g., nausea, vomiting, sore throat) occurred less frequently in patients undergoing INB as compared with those undergoing GA. CONCLUSION: Infraclavicular brachial plexus block with a short-acting local anesthetic was associated with time-efficient anesthesia, faster recovery, fewer adverse events, better analgesia, and greater patient acceptance than GA followed by wound infiltration with a local anesthetic in outpatients undergoing hand and wrist surgery.

Adolescent↗

PubMed2002

A comparison of intertendinous and classical approaches to popliteal nerve block using magnetic resonance imaging simulation.

UNLABELLED: The classical approach to sciatic nerve block in the popliteal fossa (popliteal block) often requires multiple attempts to localize the sciatic nerve. Recently, it has been suggested that an intertendinous approach to popliteal block may result in a more consistent localization of the sciatic nerve. In the current study, we compared anatomical landmarks for the intertendinous and classical approaches to popliteal block with respect to the accuracy in localizing the sciatic nerve using magnetic resonance imaging simulation. Two anesthesiologists experienced in popliteal block drew landmarks for the intertendinous and classical approaches on 10 volunteers; a 1.5 Tesla superconducting magnet was used to obtain simultaneous, 10-mm thick, fast-spin echo proton density transverse axial sequences of the lower extremities. Using these acquired images, the two approaches were simulated off-line using previously identified landmarks. The spatial relationships of the simulated needle paths to the nerves and vessels in the popliteal fossa, as well as other relevant structures, were measured and compared. Simulation of the intertendinous approach to popliteal block resulted in needle-to-sciatic nerve contact in 14 legs (70%) versus 5 legs (25%) when the classical approach was used (P < 0.05). We conclude that the intertendinous approach might result in a more consistent localization of the sciatic nerve and may decrease the risk of sciatic vessel puncture. IMPLICATIONS: A simulation of popliteal block using magnetic resonance imaging in volunteers suggests that using tendons of the hamstring muscles as the anatomical landmarks yields a more consistent localization of the sciatic nerve.

Adult↗

PubMed2002

Training requirements for peripheral nerve blocks.

PURPOSE OF REVIEW: To review the current recommendations and literature on training in regional anesthesia and suggest an improved model to prepare graduating residents better in the practice of regional anesthesia. RECENT FINDINGS: Patient satisfaction, a growing demand for cost-effective anesthesia, and a favorable postoperative recovery profile have all resulted in the growing demand for regional anesthesia. However, it has been well established that the current teaching of regional anesthesia is suboptimal. SUMMARY: A structured regional anesthesia rotation, a dedicated team of mentors with training in regional anesthesia, and adequate clinical volume are a pre-requisite for adequate training, but they may not be available in many anesthesia residency training programs. As the demand for regional anesthesia continues to increase in the years to come, it is imperative to ensure adequate education of graduating residents to meet this demand. In order to achieve this goal, the present recommendations should be re-evaluated, and perhaps a proficiency in a core group of widely applicable and relatively simple nerve blocks should be mastered by all graduates.

Journal Article↗

PubMedDate not supplied

Painful paresthesiae are infrequent during brachial plexus localization using low-current peripheral nerve stimulation.

BACKGROUND: Considerable controversy exists over the relationship of paresthesia to nerve stimulation. The purpose of this study was to determine the frequency with which patients report paresthesia at the point that an acceptable motor response is obtained to low-intensity current electrical stimulation. METHODS: Low-intensity current nerve stimulation (0.6 mA, 200 microseconds, 2 Hz) was used to identify the brachial plexus in 64 consecutive patients having shoulder or arm surgery with an interscalene block. During nerve localization and while maintaining a motor response (0.20 mA-0.40 mA), the patients were queried regarding any radiating sensation or pain (paresthesia) in the shoulder or extremity on the side of the blockade. Sensory distribution of the block, motor strength of the arm muscles, and adequacy of anesthesia were used to assess the extent of blockade. RESULTS: Ninety-five percent of patients had satisfactory surgical anesthesia. None of the patients spontaneously reported having a paresthesia during nerve stimulation. However, on careful questioning, half of the patients (55%) reported electrical paresthesia, defined as dull tingling sensation traveling down to their hands and coinciding with the motor response. In addition, most patients (71%) spontaneously reported having a mild, radiating paresthesia on initial injection of local anesthetic. CONCLUSIONS: Painful paresthesiae should be infrequent when a low-stimulating current is used to identify the neural components of the brachial plexus and when the block needle is advanced slowly. Low-current intensity nerve stimulation can be used to achieve successful interscalene block with minimal discomfort to the patient.

Adult↗

PubMedDate not supplied

Injection pressures by anesthesiologists during simulated peripheral nerve block.

BACKGROUND AND OBJECTIVES: Anesthesiologists typically rely on a subjective evaluation ("syringe feel") of possible abnormal resistance to injection while performing a peripheral nerve block (PNB). A greater force required to perform the injection is believed to be associated with intraneural injection. The hypothesis of this study is that anesthesiologists vary in their perception of "normal" injection force, that the syringe feel method is inconsistent in estimating resistance, and that needle design may affect the injection force. METHODS: Thirty anesthesiologists were asked to inject a local anesthetic, as they would in their everyday practice, through a commonly used syringe and needle assembly. Injection force was measured using an in-line manometer coupled to a computer via an analog-to-digital conversion board. In addition, injection force at clinically relevant injection speeds was determined using 3 differently sized needles from 4 different manufacturers. RESULTS: During a steady injection rate, all anesthesiologists perceived an increase in the force required to inject, even with minor pressures changes (0.6 +/- 0.3 psi). However, the 30 anesthesiologists, 21 (70%) initiated injection using a force that resulted in pressures greater than 20 psi; 15 (50%) used a force greater than 25 psi, and 3 (10%) exerted pressures greater than 30 psi. Pressures varied as much as 20-fold among needles of the same gauge/length from different manufacturers (P <.01). CONCLUSIONS: Anesthesiologists vary widely in their perception of appropriate force and rate of injection during PNB. The syringe-feel method of assessing injection force is inconsistent and may be further affected by variability in needle design.

Analysis of Variance↗