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Biomedical subjects

J M Neal

Publications and source records attributed to J M Neal.

At least 19 recordsLinked to original sources
PubMed2000

Spinal nerve function in five volunteers experiencing transient neurologic symptoms after lidocaine subarachnoid anesthesia.

UNLABELLED: The etiology of transient neurologic symptoms (TNS) after 5% lidocaine spinal anesthesia remains undetermined. Previous case reports have shown that patients acutely experiencing TNS have no abnormalities on neurologic examination or magnetic resonance imaging. The aim of our study was to determine whether volunteers with TNS would exhibit abnormalities in spinal nerve electrophysiology. Twelve volunteers with no history of back pain or neurologic disease underwent baseline electromyography (EMG), nerve conduction studies, and somatosensory-evoked potential (SSEP) testing. Then, the volunteers were administered 50 mg of 5% hyperbaric lidocaine spinal anesthesia and were placed in a low lithotomy position (legs on four pillows). The next day, all volunteers underwent follow-up EMG, nerve conduction, and SSEP testing and were questioned and examined for the presence of complications including TNS (defined as pain or dysthesia in one or both buttocks or legs occurring within 24 h of spinal anesthesia). Volunteers who had TNS underwent additional EMG testing 4-6 wk later. Five of the 12 volunteers reported TNS. No volunteer had an abnormal EMG, nerve conduction study, or SSEP at 24 h follow up, nor were there any changes in EMG studies at delayed testing in the five volunteers experiencing TNS. On statistical analysis, the right peroneal and the right tibial nerve differed significantly for all volunteers from pre- to postspinal testing. When comparing pre- and postspinal testing of the TNS and non-TNS volunteers, statistically significant changes occurred in the nerve conduction tests of the right peroneal and left tibial nerve. There was no difference in measurements of F response, H reflex latency, amplitude, or velocity for either leg. Multivariate analysis of variance showed no significant difference between TNS and non-TNS volunteers for the changes in the nine nerve conduction tests when considered together (P = 0.4). We conclude that acute TNS after lidocaine spinal anesthesia did not result in consistent abnormalities detectable by EMG, nerve conduction studies, or SSEP in five volunteers. IMPLICATIONS: Electrophysiologic testing in volunteers experiencing transient neurologic symptoms is not abnormal.

Adult↗
PubMed2000

Sedation during spinal anesthesia.

BACKGROUND: Central neuraxial anesthesia has been reported to decrease the dose of both intravenous and inhalational anesthetics needed to reach a defined level of sedation. The mechanism behind this phenomenon is speculated to be decreased afferent stimulation of the reticular activating system. The authors performed a two-part study (nonrandomized pilot study and a subsequent randomized, double-blind, placebo-controlled study) using the Bispectral Index (BIS) monitor to quantify the degree of sedation in unmedicated volunteers undergoing spinal anesthesia. METHODS: Twelve volunteers underwent BIS monitoring and observer sedation scoring (Observer's Assessment of Alertness/Sedation Scale [OAA/S]) before and after spinal anesthesia with 50 mg hyperbaric lidocaine, 5%. Subsequently, 16 volunteers blinded to the study were randomized to receive spinal anesthesia with 50 mg hyperbaric lidocaine, 5% (n = 10) or placebo (n = 6) and underwent BIS and OAA/S monitoring. RESULTS: In part I, significant changes in BIS scores of the volunteers occurred progressively (P = 0.003). The greatest variations from baseline BIS measurement occurred at 30 and 70 min. In part II, there were significant decreases in OAA/S and self-sedation scores for patients receiving spinal anesthesia versuscontrol patients (P = 0.04 and 0. 01, respectively). The greatest decrease in OAA/S scores occurred at 60 min. BIS scores were similar between groups (P = 0.4). CONCLUSIONS: Spinal anesthesia is accompanied by significant sedation progressively when compared with controls as measured by OAA/S and self-sedation scores. This effect was not related to block height. The late sedation observed by OAA/S at 60 min may indicate a second mechanism of sedation, such as delayed rostral spread of local anesthetics. BIS was not a sensitive measure of the sedation associated with spinal anesthesia in the randomized, blinded portion of this study.

Adult↗
PubMed1999

The neurotoxicity of drugs given intrathecally (spinal)

Overall, most spinal drugs in clinical use have been poorly studied for spinal cord and nerve root toxicity. Laboratory studies indicate that all local anesthetics are neurotoxic in high concentrations and that lidocaine and tetracaine have neurotoxic potential in clinically used concentrations. However, spinal anesthesia (including lidocaine and tetracaine) has a long and enviable history of safety. Spinal analgesics such as morphine, fentanyl, sufentanil, clonidine, and neostigmine seem to have a low potential for neurotoxicity based on laboratory and extensive clinical use. Most antioxidants, preservatives, and excipients used in commercial formulations seem to have a low potential for neurotoxicity. In addition to summarizing current information, we hope that this review stimulates future research on spinal drugs to follow a systematic approach to determining potential neurotoxicity. Such an approach would examine histologic, physiologic, and behavioral testing in several species, followed by cautious histologic, physiologic, and clinical testing in human volunteers and patients with terminal cancer refractory to conventional therapy.

Analgesics↗
PubMed1999

Dilution of spinal lidocaine does not alter the incidence of transient neurologic symptoms.

BACKGROUND: Although it has been suggested that the dilution of 5% hyperbaric lidocaine before injection for spinal anesthesia may decrease the incidence of transient neurologic symptoms, previous studies have not noted a decreased incidence between 5% and 2% lidocaine. The aim of the current study was to determine whether the incidence of transient neurologic symptoms could be altered by further diluting spinal lidocaine from 2.0% to 0.5%. METHODS: One hundred nine patients with American Society of Anesthesiologists physical status 1 or 2 undergoing outpatient knee arthroscopy were randomized in a double-blind fashion to receive 50 mg hyperbaric spinal lidocaine as a 2.0%, 1.0%, or 0.5% concentration. On the third postoperative day, patients were contacted by a blinded investigator and questioned regarding the incidence of postoperative complications, including transient neurologic symptoms, defined as pain or dysthesia in one or both buttocks or legs occurring within 24 h of surgery. RESULTS: The incidence of transient neurologic symptoms did not differ among patients receiving 2.0% (incidence of 15.8%), 1.0% (incidence of 22.2%), and 0.5% (incidence of 17.1%) lidocaine (P = 0.756). CONCLUSIONS: For ambulatory patients undergoing arthroscopy, the incidence of transient neurologic symptoms is not reduced by decreasing spinal lidocaine concentrations from 2.0% to 1.0% or 0.5%. The incidences of transient neurologic symptoms with the 0.5%, 1.0%, and 2.0% solutions are similar to previously reported incidences for 5.0% lidocaine, suggesting that dilution of lidocaine from 5.0% to 0.5% does not change the incidence of these symptoms.

Adult↗
PubMed1998

The effect of epinephrine on small-dose hyperbaric bupivacaine spinal anesthesia: clinical implications for ambulatory surgery.

UNLABELLED: The effect of adding epinephrine to small doses of spinal bupivacaine on the duration of sensory motor block has not been carefully investigated. Twelve volunteers underwent hyperbaric bupivacaine spinal anesthesia (7.5 mg) with and without epinephrine (0.2 mg) in a randomized, double-blind, cross-over fashion. Sensory block was assessed with pinprick, transcutaneous electrical stimulation (TES) equivalent to surgical stimulation (at umbilicus, pubis, knee, and ankle), and tolerance of a pneumatic thigh tourniquet. Motor block was assessed with isometric force dynamometry. Discharge criteria were defined as return of pinprick sensation to dermatome S2, ability to ambulate, and ability to urinate. Extent of sensory block to pinprick over time was unaffected by the addition of epinephrine. However, epinephrine prolonged tolerance of TES at the pubis, knee, and ankle (33-48 min, P < 0.05) and of thigh tourniquet (30 min, P < 0.01). Motor block was prolonged by epinephrine at the quadriceps and gastrocnemius muscles (by 23 and 51 min, respectively, P < 0.002). Achievement of discharge criteria was prolonged by 48 min by the addition of epinephrine (P < 0.01). Thus, epinephrine may prolong surgical anesthesia for lower abdominal and lower extremity surgery and delay time until patients achieve discharge criteria. IMPLICATIONS: Using a cross-over study design, 12 volunteers underwent bupivacaine spinal anesthesia with and without epinephrine. This study suggests that adding epinephrine to bupivacaine may prolong surgical anesthesia and also delay patients' discharge.

Adult↗
PubMed1998

Premedication with fentanyl and midazolam decreases the reliability of intravenous lidocaine test dose.

UNLABELLED: This study was performed to determine whether premedication with midazolam and fentanyl prevents reliable detection of an i.v. lidocaine test dose. Thirty ASA physical status I or II patients received either 3 mL of saline or 1.5 mg of midazolam (1.5 mL) plus 75 microg of fentanyl (1.5 mL) i.v. in a randomized, double-blind fashion. Five minutes later, lidocaine 1 mg/kg was injected i.v. At 1.5 min before and every minute after lidocaine administration, each subject was questioned regarding the presence of four symptoms of systemic lidocaine toxicity. Any new tinnitus, perioral numbness, metallic taste, or light-headedness within 5 min after lidocaine administration was considered a positive response. All 15 patients in the saline group (100% sensitivity) had a positive response to i.v. lidocaine, but only 9 of 15 patients in the sedation group had a positive response (60% sensitivity; P = 0.017). We conclude that midazolam and fentanyl premedication decreases the reliability of subjective detection of i.v. lidocaine. IMPLICATIONS: Anesthesiologists often rely on subjective symptoms to prevent local anesthetic toxicity while performing regional anesthesia. Sedatives are often administered during the administration of regional anesthesia. This study demonstrates that typical sedation decreases the reliability of detection of local anesthetic toxicity by subjective symptoms.

Adult↗
PubMed1998

Quantitative analysis of respiratory, motor, and sensory function after supraclavicular block.

UNLABELLED: The incidence and clinical significance of hemidiaphragmatic paresis after supraclavicular block of the brachial plexus is unknown. Eight healthy volunteers received a supraclavicular block with a standard technique using 30 mL of 1.5% lidocaine. Respiratory function was assessed with ultrasound of the diaphragm, respiratory inductive plethysmography (RIP), and pulmonary function tests (PFT) every 20 min. Sensory block was assessed with pinprick and motor block with isometric force dynamometry every 20 min. Four of eight subjects demonstrated hemidiaphragmatic paresis on both ultrasound and RIP. No subject experienced changes in PFT values or subjective symptoms of respiratory difficulty. Motor and sensory blockade outlasted hemidiaphragmatic paresis. These results are contrasted to the often symptomatic, 100% incidence of hemidiaphragmatic paresis seen after interscalene block. In this study of healthy volunteers, supraclavicular block was associated with a 50% incidence (95% confidence interval 14-86) of hemidiaphragmatic paresis that was not accompanied by clinical evidence of respiratory compromise. IMPLICATIONS: Interscalene block is always associated with diaphragmatic paralysis and respiratory compromise. The significance of these side effects after supraclavicular block is unknown. Using sensitive measures of respiratory function, we determined that diaphragmatic paralysis occurs less often with the supraclavicular approach and is not associated with respiratory difficulties in healthy subjects.

Adult↗
PubMed1997

A collaborative approach to minimally invasive direct coronary artery bypass.

Minimally invasive direct coronary artery bypass (MIDCAB) graft is a surgical technique that is becoming more widely accepted. Through a collaborative effort--interhospital and intrahospital--surgical team members at two hospitals in Kentucky made significant improvements on the MIDCAB procedure that positively influenced patient outcomes (e.g., less time in intensive care, shorter hospital stays, fewer complication, cost savings to the patients and institutions). This article reviews those collaborative efforts and outcomes.

Coronary Disease↗
PubMed1996

Prospective study of the incidence of transient radicular irritation in patients undergoing spinal anesthesia.

BACKGROUND: There is considerable controversy regarding the role of subarachnoid 5% hyperbaric lidocaine in the syndrome transient radicular irritation (TRI). This randomized, double-blinded, prospective study was designed to determine the incidence of TRI and identify factors possibly contributing to its development. METHODS: One hundred fifty-nine ASA physical status 1 or 2 patients undergoing outpatient knee arthroscopy or unilateral inguinal hernia repair were prospectively randomized to receive spinal anesthesia with 5% hyperbaric lidocaine with epinephrine (60 mg with 0.2 mg epinephrine for arthroscopy or 75 mg with 0.2 mg epinephrine for hernia repair), 2% isobaric lidocaine without epinephrine (60 mg for arthroscopy or 75 mg for hernia repair), or 0.75% hyperbaric bupivacaine without epinephrine (7.5 mg for arthroscopy or 9.0 mg for hernia repair) in a double-blinded fashion. On the 3rd postoperative day, patients were contacted by a blinded investigator and questioned regarding the incidence of postoperative complications including TRI, defined as back pain with radiation down one or both buttocks or legs occurring within 24 h after surgery. Postoperatively, time from injection to block resolution, ambulation, voiding, and ready for discharge were recorded by a postanesthesia care unit nurse blinded to the group assignment. RESULTS: The incidence of TRI was greater in patients receiving lidocaine than in those receiving bupivacaine (16% vs. 0%; P = 0.003). There was no difference in the incidence of TRI between the patients receiving 5% hyperbaric lidocaine with epinephrine and those receiving 2% isobaric lidocaine without epinephrine (16% vs. 16%; P = 0.98). The incidence of TRI was greater in patients undergoing arthroscopy than in those undergoing hernia repair (13% vs. 5%; P = 0.04). There was no difference in discharge times in patients receiving bupivacaine versus those receiving hyperbaric lidocaine with epinephrine (292 vs. 322 min; P = 0.61). CONCLUSIONS: The incidence of TRI is greater with lidocaine than bupivacaine, decreasing the lidocaine concentration to 2% does not prevent TRI, and surgical position may be an important contributing factor. Discharge times at our institution are not different when equipotent doses of 0.75% hyperbaric bupivacaine or 5% hyperbaric lidocaine with 0.2 mg epinephrine are used in ambulatory patients undergoing spinal anesthesia.

Adult↗
PubMed1996

Dose-response characteristics of spinal bupivacaine in volunteers. Clinical implications for ambulatory anesthesia.

BACKGROUND: Small doses of bupivacaine may be a reasonable choice for spinal anesthesia for patients having ambulatory surgery. However, few dose-response data are available to guide the selection of reasonable doses of bupivacaine for different ambulatory procedures. METHODS: Eight volunteers per group were randomized to receive 3.75, 7.5, or 11.25 mg of 0.75% bupivacaine with 8.25% dextrose in a double-blind manner. Sensory block was assessed with pinprick, transcutaneous electrical stimulation equivalent to surgical incision at the ankle, knee, pubis, and umbilicus, and with duration of tolerance to pneumatic thigh tourniquet. Motor block at the quadriceps and gastrocnemius muscles was assessed with isometric force dynamometry. Times until recovery from spinal anesthesia were recorded. Dose-response relationships were determined by linear regressions. Mean (95% confidence intervals) for durations of sensory and motor block per milligram of bupivacaine administered were calculated from linear regressions. RESULTS: Significant dose-response relationships (P < 0.006) were determined for sensory block, motor block, and time until recovery (R from 0.6 to 0.9). Within the range of doses studied, each additional milligram of bupivacaine was associated with an increase in duration of tolerance to transcutaneous electrical stimulation of 10 (7 to 13) min, an increase in tolerance to tourniquet of 7 (2 to 11) min, an increase in duration of motor block of 8 (5 to 12) min, and an increase in time until recovery of 21 (17 to 25) min. CONCLUSIONS: These dose-response data may guide the selection of reasonable doses of bupivacaine for various outpatient procedures, although individual responses vary.

Adult↗
PubMed1995

Calcaneal ultrasonic measurements discriminate hip fracture independently of bone mass.

We studied 336 elderly white women, of whom 22 had previously suffered a hip fracture and 22 had previously suffered a vertebral fracture. All subjects were 60 years old or older with a mean age of 73:7 years. Measurements of ultrasonic transmission velocity (UTV), broad-band ultrasonic attenuation (BUA) and stiffness (STF) were made at the os calcis using a Lunar Achilles ultrasound device. Measurements of lumbar spine bone mineral density (L2-4 BMD) and femoral neck BMD were made using dual-energy X-ray absorptiometry. The fracture groups were significantly older and had more years since menopause than the control groups. Logistic regression showed that measurements of UTV, STF and BUA discriminated between fracture and non-fracture subjects for both the hip (p < 0.001) and spine (p < 0.05). Femoral neck BMD discriminated both hip and vertebral fractures from controls (p < 0.001 and p < 0.01, respectively). Spinal BMD discriminated between subjects with vertebral fractures and those without (p < 0.01), but not hip fractures (p = 0.64). For hip fracture, areas under receiver-operating characteristic (ROC) curves were 0.85 for UTV, 0.83 for STF, 0.79 for BUA, 0.78 for femoral neck BMD and 0.53 for spinal BMD. For vertebral fracture, areas under the ROC curve were 0.68 for UTV, 0.70 for STF, 0.66 for BUA, 0.66 for femoral neck BMD and 0.67 for spinal BMD.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

Fentanyl prolongs lidocaine spinal anesthesia without prolonging recovery.

Lidocaine spinal anesthesia is a popular anesthetic for short procedures due to its brief duration. The addition of fentanyl may improve the quality and duration of lidocaine spinal anesthesia. Eight volunteers received plain lidocaine 5% in dextrose (50 mg) both with and without 20 micrograms of fentanyl in a randomized, double-blind, cross-over fashion. Sensory analgesia was assessed with pinprick, cold, touch, transcutaneous electrical stimulation equivalent to surgical incision, and duration of tolerance of pneumatic thigh tourniquet. Motor block was assessed with isometric force dynamometry. Regression of pinprick, touch, and cold was prolonged with fentanyl. Duration of tolerance of electrical stimulation at the umbilicus, hip, knee, and ankle was increased with fentanyl (181% increase from plain lidocaine on average; P < 0.01). Duration of tolerance of tourniquet-induced pain was increased by an average of 48% with addition of fentanyl (P = 0.02). Neither motor block nor time to void was prolonged with fentanyl. Pruritus occurred in all subjects receiving fentanyl but was treated easily and were well tolerated. We recommend the addition of 20 micrograms of fentanyl to lidocaine spinal anesthesia as a means to improve duration of sensory anesthesia without prolonging recovery of motor function or time to micturition.

Adult↗
PubMed1995

The effects of epinephrine on lidocaine spinal anesthesia: a cross-over study.

The efficacy of epinephrine for prolonging the duration of lidocaine spinal anesthesia remains controversial. Seven volunteers were randomized in a double-blind manner to receive two 50-mg lidocaine (in dextrose 7.5%) spinal anesthetics with and without epinephrine (0.2 mg). Sensory analgesia was assessed with transcutaneous electrical stimulation (TES) equivalent to surgical incision and compared to standard pinprick dermatomal levels. Motor block was assessed with surface electromyography (EMG) and isometric force dynamometry. Intravenous fluids were administered by a standardized regimen, and time until ability to void was determined. Addition of epinephrine significantly prolonged duration of surgical anesthesia in the lumbar and sacral dermatomes by an average of 16-29 min (P = 0.03), but not in thoracic dermatomes. Although there was a trend toward prolongation of motor block with addition of epinephrine, this did not reach statistical significance. Epinephrine significantly prolonged duration until ability to void from 153 +/- 27 to 234 +/- 50 min (P = 0.0001). Thus, addition of epinephrine to lidocaine may be indicated to prolong duration of anesthesia for lower body operations. However, delayed recovery of ability to void may also prolong time until discharge after ambulatory surgery.

Adult↗
PubMed1995

Comparison of 5% with dextrose, 1.5% with dextrose, and 1.5% dextrose-free lidocaine solutions for spinal anesthesia in human volunteers.

The use of lidocaine in concentrations less than 5% for spinal anesthesia may be advantageous but has not been carefully studied. Lidocaine 50 mg (1.5% with dextrose and 1.5% dextrose-free) was administered to eight volunteers in a randomized, double blind, cross-over fashion. All of these subjects had previously received 5% lidocaine with dextrose using the same experimental protocol. Sensory analgesia was assessed with pinprick, transcutaneous electrical stimulation (TES) equivalent to surgical incision, and duration of tolerance of pneumatic thigh tourniquet. Motor block was assessed with isometric force dynamometry. Peak dermatomal level was the highest and duration until regression of pinprick the longest with the 5% solution (P < 0.05). Duration of tolerance to TES was increased (33 +/- 10 min) with the 5% solution (P < 0.04). Duration of tolerance to tourniquet pain was increased (11 +/- 3 min) with the 5% solution (P < 0.02). Duration of motor block was increased (45 +/- 9 min) with the 5% and the 1.5% without dextrose solutions (P < 0.04). Time to void was increased (33 +/- 5 min) with the 5% solution (P < 0.03). In conclusion, the use of different solutions of lidocaine for spinal anesthesia results in significant differences in sensory and motor block and time until recovery of micturition.

Adult↗
PubMed1995

Oral clonidine prolongs lidocaine spinal anesthesia in human volunteers.

BACKGROUND: Premedication with oral clonidine may improve the quality and duration of lidocaine spinal anesthesia, but this effect has not been examined in a quantitative fashion. METHODS: Eight volunteers received 50 mg lidocaine (1.5% dextrose free) both with and without 0.2 mg oral clonidine 1.5 h before spinal anesthesia in a randomized, double-blind, placebo-controlled, crossover fashion. Sensory block was assessed by pinprick, transcutaneous electric stimulation equivalent to surgical incision, and duration of tolerance to pneumatic thigh tourniquet. Motor block at the quadriceps and gastrocnemius muscles was assessed by isometric force dynamometry. Episodes of bradycardia, hypotension, and sedation were recorded. RESULTS: Regression of pinprick was unchanged with clonidine. However, duration of tolerance to electric stimulation was increased at the knee (28 +/- 24 min) and ankle (31 +/- 28 min) with clonidine (P < 0.05). The duration of tolerance to tourniquet-induced pain was increased with clonidine (14 +/- 12 min; P < 0.05). The duration of motor block was increased at the quadriceps (20 +/- 13 min) and gastrocnemius (33 +/- 24 min) muscle groups with clonidine (P < 0.05). Although clonidine decreased systolic blood pressure (13 +/- 4 mmHg, P < 0.003) and heart rate (13 +/- 5 beats/min; P = 0.02), no subjects had hypotension or bradycardia. The incidence of sedation was greater with clonidine than with plain lidocaine (50% vs. 0%, P < 0.04). DISCUSSION: Premedication with oral clonidine prolonged sensory and motor block from lidocaine spinal anesthesia. The exact mechanism whereby oral clonidine prolongs spinal anesthesia remains to be determined.

Administration, Oral↗