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Biomedical subjects

R A Stevens

Publications and source records attributed to R A Stevens.

67 records · Page 4Linked to original sources
PubMedDate not supplied

Time course of the effects of cervical epidural anesthesia on pulmonary function.

BACKGROUND AND OBJECTIVES: During cervical epidural anesthesia the C4, C5, and sometimes C3 nerve roots are anesthetized. One might therefore expect pulmonary compromise due to the block of the phrenic nerve if anesthesia extends to C3. This study was conducted to measure the effects of cervical epidural anesthesia using 2% lidocaine on pulmonary function, with specific attention given to the time course of pulmonary changes in relation to spread of analgesia. METHODS: Fifteen adult patients without preexisting lung disease undergoing carotid endarterectomy, breast surgery, or cervical epidural steroid injection were enrolled. Cervical epidural anesthesia was performed at the C7-T1 interspace using 300 mg lidocaine with epinephrine. Pulmonary function, including forced expiratory volume in one second (FEV1), forced vital capacity (FVC), maximum inspiratory pressure (MIP), and SpO2 while breathing room air were measured prior to and 5, 10, 20, and 40 minutes after lidocaine injection. RESULTS: Analgesia to pinprick reached median dermatomes of C3 to T8 (range: C2-T12) by 20 minutes after lidocaine injection. FEV1 and FVC decreased approximately 12-16% between 20 and 40 minutes after injection. Maximum inspiratory pressure and SpO2 did not significantly change. CONCLUSIONS: Cervical epidural anesthesia using 300 mg lidocaine results in measurable reduction in bedside pulmonary functions concomitant with the spread of analgesia to the C3 dermatome. These changes were complete 20 minutes after lidocaine injection. In patients without preexisting lung disease, these changes were not clinically significant, except in one patient. We conclude that motor block of the phrenic nerve is incomplete under the conditions of this study.

Adult↗
PubMedDate not supplied

Reversal of lidocaine with epinephrine epidural anesthesia using epidural saline washout.

BACKGROUND AND OBJECTIVES: Prolonged motor and sensory block following epidural anesthesia can be associated with extended postoperative care unit stays and patient dissatisfaction. Previous studies have demonstrated a more rapid motor recovery following the administration of epidural crystalloids in patients who had received plain bupivacaine and lidocaine epidural anesthesia. However, epinephrine is commonly added to local anesthetics to improve the quality and prolong the duration of the epidural block. The objective of this study was to determine the relationship of 0.9% NaCl epidural catheter flush volume (i.e., washout) to the recovery of motor and sensory block in patients undergoing 2% lidocaine with epinephrine epidural anesthesia. METHODS: A prospective, randomized, double-blind study design was utilized. Thirty-three subjects scheduled for elective gynecologic or obstetrical surgical procedures underwent epidural anesthesia using 2% lidocaine with epinephrine (1:200,000). A T4 dermatome level of analgesia, determined by toothpick prick, was maintained intraoperatively. Following surgery, subjects were randomized to 1 of 3 treatment groups. Group 1 (control, n = 11) received no epidural 0.9% NaCl (normal saline [NS]) postoperatively. Group 2 (15 mL NS x 1, n = 10) received an epidural bolus of 15 mL NS. Group 3 (15 mL NS x 2, n = 12) received an epidural bolus of 15 mL NS postoperatively and a second 15-mL NS bolus 15 minutes later. Assessment of motor and sensory block was performed at 15-minute intervals until complete motor and sensory recovery. RESULTS: Times to partial and full motor and sensory recovery were significantly faster in the epidural NS groups than in the control group. Full motor recovery was more rapid in subjects receiving two 15-mL NS epidural NS boluses (30 mL total) compared with those receiving a single 15-mL NS bolus (108 +/- 9 min v 136 +/- 13 min) and significantly faster than control group subjects (153 +/- 14 min). Both NS x 1 and NS x 2 epidural bolus groups experienced significantly reduced times to complete sensory recovery when compared with the control group (NS x 1 = 154 +/- 13 min, NS x 2 = 153 +/- 9 min, control 195 +/- 14 min). CONCLUSIONS: A more rapid recovery of motor and sensory block in patients undergoing 2% lidocaine with epinephrine epidural anesthesia can be achieved with the use of 30 mL NS epidural washout. Reg Anesth Pain Med 2001;26:246-251.

Adjuvants, Anesthesia↗
PubMedDate not supplied

The recovery profile of hyperbaric spinal anesthesia with lidocaine, tetracaine, and bupivacaine.

BACKGROUND AND OBJECTIVES: Surgical procedures previously considered too lengthy for the ambulatory surgery setting are now being performed during spinal anesthesia. The complete recovery profile of tetracaine and bupivacaine are now of interest but are not available in the literature. This study was conducted to compare times to ambulation, voiding, and complete block resolution, as well as the incidence of back and radicular pain, after spinal anesthesia with lidocaine, bupivacaine, and tetracaine. METHODS: Twelve adult volunteers underwent spinal anesthesia on three separate occasions with three local anesthetics (lidocaine 100 mg, bupivacaine 15 mg, and tetracaine 15 mg in hyperbaric solutions) in random order and in a double-blind fashion. A 24-gauge Sprotte spinal needle was placed at the L2-3 interspace. The level of analgesia to pinprick was determined moving cephalad in the midclavicular line until a dermatome was reached at which the prick felt as sharp as over an unblocked dermatome. One dermatome caudad to this point was recorded every 5 minutes as the level of analgesia. We also recorded the times to voiding, unassisted ambulation, and complete resolution of sacral anesthesia. RESULTS: There was no difference between tetracaine and bupivacaine in time taken for two- and four-segment regression of the analgesia level. However, times to ambulation and complete resolution of the block were significantly shorter with bupivacaine then with tetracaine. With lidocaine, times to four-segment regression, ambulation, voiding, and complete regression of the block were significantly shorter than with bupivacaine and tetracaine. Time to two-segment regression did not differ among local anesthetics. Back and radicular pain symptoms were reported by three subjects after lidocaine subarachnoid block but not after tetracaine or bupivacaine. CONCLUSION: Among individual subjects, lidocaine exhibited the shortest recovery profile. However, the recovery profiles of the three anesthetics were very variable between subjects. Time to meeting discharge criteria after bupivacaine or tetracaine was faster in a few subjects than that after lidocaine in other subjects. For ambulatory anesthesia, times to two- and four-segment regression do not accurately predict time to readiness for discharge after spinal anesthesia.

Adult↗
PubMedDate not supplied

Routes of opioid analgesic therapy in the management of cancer pain.

BACKGROUND: The availability of various routes of administration of opioid analgesics can be confusing when determining an appropriate, efficacious, and cost-effective regimen to manage cancer pain. METHODS: The indications, contraindications, and pharmacokinetic properties of oral, intravenous, subcutaneous, transdermal, transmucosal, rectal, and perispinal routes of opioid administration are reviewed. RESULTS: To determine the most efficacious, cost-effective, and user-friendly option to manage cancer pain, several factors must be considered: the ability of the patient to use a specific type of delivery system, the efficacy of that system to deliver acceptable analgesia, the ease of use for the patient and family, the potential or actual complications associated with that system, and the cost. CONCLUSIONS: Administering opioids to manage cancer pain requires knowledge of potency relative to morphine and bioavailability of the route chosen. Changes in the route, dosage, or opioid used should be accompanied with close patient follow-up.

Analgesics, Opioid↗
PubMedDate not supplied

Public opinion, knowledge, and Medicare reform.

A review of public opinion and focus-group research reveals consistently inadequate understanding of Medicare by the public and misinterpretation of public opinion information by policy advocates. Closer analysis of apparent conflicts in values related to self-sufficiency, personal responsibility, and government, however, reveals strong support for the basic premises of social insurance embodied in Medicare. The likelihood of meaningful policy discussions about Medicare depends, in part, on whether the policy and research communities can find ways to provide the electorate with the knowledge they need to understand the implications of reform.

Attitude to Health↗
PubMedDate not supplied

Differential epidural block.

BACKGROUND AND OBJECTIVES: Loss of sensation to pinprick and cold are commonly used to test the extent of epidural anesthesia. To see what difference exists between the level of epidural block determined by various sensory modalities, we performed this study in ten volunteers using epidural anesthesia with plain 3% chloroprocaine hydrochloride. METHODS: Four injections of chloroprocaine were made via an epidural catheter inserted at L2-3 with increasing larger volumes. Sensory modalities tested were (1) absence of sensation when tested by pinprick (anesthesia), (2) loss of a sharp sensation compared to an unblocked dermatome when tested by pinprick (analgesia), and (3) loss of cold sensation when tested with an alcohol swab compared to an unblocked dermatome. RESULTS: At 20 minutes after each injection the level of anesthesia was found to be most caudad and the level of analgesia most cephalad. The zone of differential block was greater than four dermatomes at the highest level of block tested. The level of loss of cold sensation was found between the other two levels. Differences between the levels of analgesia and cold sensation tended to be greater with more extensive block. Differences between levels of anesthesia and cold sensation did not significantly change as the extent of epidural anesthesia was increased. CONCLUSIONS: This study establishes the existence of a differential epidural anesthesia during high thoracic block with chloroprocaine and suggests that the intensity of block diminishes as distance from site of injection increases.

Adult↗
PubMedDate not supplied

Back pain after epidural anesthesia with chloroprocaine in volunteers: preliminary report.

The incidence, character and treatment of backache associated with epidural anesthesia (EA) using 3% chloroprocaine (2-CP, Nesacaine-MPF) were observed in ten volunteers undergoing a study of the effects of EA upon plasma catecholamines. Three levels of epidural analgesia were sequentially sought, T10, T4 and C8, in ascending order. Each block was allowed to fully dissipate prior to the next injection. For the first, second and third injections, 15-20 ml, 25-35 ml and 52-60 ml, respectively, of 3% 2-CP were injected via an epidural catheter. Mean total volume of 2-CP injected was 103 ml (range, 92-115 ml) over seven hours. Back pain was first reported after as little as 15 ml (mean +/- SEM, 24.0 +/- 3.9 ml; range, 15-45 ml). The pain was described as a dull ache deep in the lumbar back, ranging in severity from mild to severe. No profound spasm of the erector spinae muscles was observed. Mean verbal analog scale pain scores after regression of the first, second and third blocks were 2.2, 4.3 and 6.5, respectively. Epidural fentanyl (100-200 micrograms) was effective in providing rapid relief of the pain. Large doses or possibly repeated injections of epidural Nesacaine-MPF are associated with an increased incidence and severity of postanesthesia lumbar back pain.

Adult↗
PubMedDate not supplied

Post dural puncture headache after lumbar sympathetic block: a report of two cases.

Dural puncture during lumbar sympathetic block (LSB) is a recognized but apparently uncommon complication. Interestingly, post dural puncture headache (PDPH) has not been reported as a complication of LSB. The authors report two cases of PDPH after LSB. In the first case an attempt to treat the PDPH with an epidural blood patch failed. In the second case the patient developed PDPH and a subdural block during separate LSBs. Possible anatomic explanations for these complications are discussed.

Adolescent↗
PubMedDate not supplied

The effect of pH adjustment of 0.5% bupivacaine on the latency of epidural anesthesia.

pH adjustment of lidocaine and 2-chloroprocaine has been reported to decrease the latency of epidural anesthesia (EA). The effect of alkalinization of bupivacaine on onset of surgical anesthesia has not been adequately studied to date. To determine what effect raising the pH of 0.5% bupivacaine has on the latency of EA in patients undergoing lower extremity surgery, we performed a randomized, double-blind study. Forty patients were randomly divided into two groups. Group I patients received 15 ml of a local anesthetic (LA) solution containing 0.5% bupivacaine and 0.15 mEq of NaHCO3. Group II patients received 15 ml of a standard solution of 0.5% bupivacaine. Both solutions contained freshly added epinephrine (1:200,000). After injection of LA via Tuohy needle, sensory testing was conducted using a safety pin. The pH of the LA used for Group I was 6.96 +/- 0.01 and for Group II was 5.33 +/- 0.11. No statistically significant difference was found between the anesthetic parameters tested in each group. On this basis, we find no advantage of pH adjustment of 0.5% bupivacaine for EA.

Adult↗
PubMedDate not supplied

Differential epidural block. Does the choice of local anesthetic matter?

BACKGROUND AND OBJECTIVES: It is well established that spinal anesthesia results in a differential block to the sensations of pinprick and cold temperature discrimination. However, the existence of differential block during epidural anesthesia has not always been accepted. Recently, it has been shown that lumbar epidural anesthesia with chloroprocaine and lidocaine produces a differential block to pinprick and cold sensation. The purpose of this study was to determine if the choice of local anesthetic used for epidural anesthesia has any influence on the relative levels of anesthesia, analgesia, and cold sensation. METHODS: The authors studied nine healthy subjects; each was studied three times and received one of three local anesthetics (0.75% bupivacaine, 2% lidocaine, and 3% chloroprocaine) via an epidural catheter placed into the second or third lumbar epidural space. The authors tested the following modalities compared to an unblocked dermatome: anesthesia, loss of sensation to pinprick; analgesia, loss of an equally sharp sensation to pinprick; and cold sensation, loss of cold sensation to alcohol. RESULTS: Twenty minutes after injection of the local anesthetic, zones of differential sensory block existed for all three agents tested. Anesthesia and analgesia were the most caudad and cephalad, respectively, while loss-to-cold sensation was found to be between these two levels. There was no significant difference in the dermatomal level achieved among the three local anesthetics tested. Sensory testing data observed 10 minutes later showed that no significant change had occurred. CONCLUSIONS: This study reaffirms the existence of differential sensory block during epidural anesthesia and establishes that the observed differential block appears to be independent of the local anesthetic used.

Adult↗
PubMedDate not supplied

Subjective experiences of anesthesiologists undergoing epidural anesthesia.

BACKGROUND AND OBJECTIVES: This study reports subjective experiences of nine anesthesiologists undergoing three consecutive epidural anesthetics. METHODS: Eight anesthesiologists and one nurse anesthetist, all ASA physical status 1, underwent three lumbar epidural anesthetics as part of another study. Epidural catheters were inserted via a 17-gauge Tuohy needle without sedation after local anesthesia with pH adjusted lidocaine at the second, third, or fourth lumbar interspace. Three local anesthetics (2% lidocaine HCl, 3% chloroprocaine HCl, and 0.75% bupivacaine HCl) were administered each separated by at least 48 hours. The local anesthetic was incrementally injected via the epidural catheter to achieve at least a T-1 dermatome level of analgesia. Each subject completed a written questionnaire at the end of the study regarding their experience. RESULTS: Most of the subjects (7 of 9) had no prior epidural anesthesia. Eight of nine subjects experienced at least one paresthesia during catheter insertion; this was uniformly described as a "poorly localized burning sensation," radiating to the hip or leg. All subjects reported difficulty taking a deep breath and coughing with a T-1 level of analgesia. Eight of nine subjects reported dysphoria during lidocaine epidural anesthesia. Eight of nine subjects reported moderate back pain after dissipation of chloroprocaine epidural anesthesia. CONCLUSIONS: All volunteers stated that they would change their anesthetic practice as a result of participation in this study. They believed that having experienced an epidural anesthetic made them better qualified to prepare patients for this anesthetic technique.

Adult↗