Harold Carron

Comparison of pH-adjusted lidocaine solutions for epidural anesthesia

One hundred forty-eight adult patients having epidural anesthesia for cesarean section, postpartum tubal ligation, lower extremity orthopedic procedures, or lithotriptic therapy were assigned to five groups. Group 1 patients were given a commercially prepared 1.5% lidocaine solution with 1:200,000 epinephrine plus 1 ml of normal saline per 10 ml of lidocaine; the solution pH was 4.6. Group 2 patients were given commercially prepared 1.5% lidocaine solution plus 1:200,000 epinephrine, with 1 mEq (1 ml) NaHCO3 per 10 ml of lidocaine; the solution pH was 7.15. Group 3 patients received the commercial solution of 1.5% lidocaine with 1:200,000 epinephrine; the solution pH was 4.55. Group 4 patients were given a mixture of 18 ml of 2% lidocaine with 30 ml of 1.5% lidocaine, both commercially packaged with 1:200,000 epinephrine, plus 1 mEq (1 ml) of NaHCO3 added per 10 ml of solution; the solution pH was 7.2. Group 5 patients received 1.5% plain lidocaine to which epinephrine was added to a final concentration of 1:200,000; the solution pH was 6.35. Times of onset of analgesia (time between the completion of the anesthetic injection and loss of scratch sensation at the right hip (L-2 dermatome)) and of surgical anesthesia (time between completion of injection and loss of discomfort following tetanic stimulation produced by a nerve stimulator applied to skin on the right hip) were significantly more rapid in the groups that received the pH-adjusted solutions (groups 4 and 2). Group 4 had the fastest mean onset time, 1.92 ± 0.17 min, followed by group 2, 3.31 ± 0.23 min. Onset times were progressively longer in group 5 at 4.27 ± 0.51 min, group 3 at 4.73 ± 0.37 min, and group 1 at 7.11 ± 0.82 min. The spread of sensory blockade was also significantly more rapid in the pH-adjusted groups 5, 10, and 15 min after epidural injection. In patients having cesarean sections in groups 1 and 2, plasma lidocaine levels in the maternal peripheral venous and in umbilical cord blood and Apgar scores were similar in both groups.

Stellate ganglion block.

A modified low-dose paratracheal approach to stellate ganglion block at the CS level prevents the possible complications of subarachnoid introduction of large quantities of local anesthetic, brachial plexus block, and toxic reaction to local anesthetics. It is a technically simple procedure with readily identifiable landmarks and can be performed on an outpatient basis with short recovery periods. Successful block can be readily evaluated. It is emphasized that a series of blocks is required to “disorganize” the reflex activity triggered in the internuncial pools of the spinal cord as well as in the sympathetic ganglia themselves.

Epidural steroid effects on nerves and meninges.

There have been encouraging reports of symptomatic improvement in patients with low back pain following injection of a mixture of a local anesthetic and a corticosteroid into the lumbar epidural space. However, there is a lack of animal or human studies which examined possible long-term effects of this combination on the exposed neural tissues. This study evaluated by both light and electron microscopy the effect of triamcinolone diacetate in vehicle and of the vehicle itself (both in 2% lidocaine) in 48 cats after percutaneous epidural injections were done at the lumbosacral space. When the animals were killed at 30 or 120 days, specimens of the spinal root, the root exit zone, and the meninges at the level of injection and level above and below were obtained. Because all of the histologic findings were found to be mild, it is concluded that local anesthetic-steroid combinations do not cause significant damage to neural tissues.

A comparison of low back pain patients in the United States and New Zealand: Psychosocial and economic factors affecting severity of disability☆

&NA; One hundred and ninety‐eight patients suffering from chronic low back pain seen at the University of Virginia (U.S.) Pain Center and 117 similar patients seen at the Auckland Hospital, Auckland, New Zealand (N.Z.) Pain Clinic completed a self‐report questionnaire prior to beginning comparable outpatient treatment programs. Approximately 55% of the sample from each country returned a follow‐up questionnaire 1 year later. Analyses of the results indicated that despite nearly similar between‐country reports of pain frequency and intensity, the U.S. patients, both at pre‐ and post‐testing, reported greater emotional and behavioral disruption as a correlate of their pain. U.S. patients consistently used more medication, experienced more disphoric mood states, and were more hampered in social‐sexual, recreational, and vocational functioning. Patients from both countries demonstrated a nearly equal degree of pre‐ to post‐improvement; however, the relative initial differences favoring the New Zealanders remained constant across both questionnaire administrations. At the onset of treatment, 49% of the U.S. sample and only 17% of the N.Z. patients were receiving pain‐related financial compensation. At follow‐up, patients from both countries receiving pretreatment compensation were less likely to report a return to full activity, although the relationship appeared more pronounced in U.S. patients. Seemingly, compared to the U.S., the N.Z. compensation‐disability system is used less, or for shorter durations of time, resulting in less severe life‐style disruption than appears to be the case in the U.S. patients. Seemingly, compared to the U.S., the N.Z. compensation‐disability system is used less, or for shorter durations of time. resulting in less severe life‐style disruption than appears to be the case in the U.S.

Lidocaine as an Analgesic for Experimental Pain

The purpose of this study was to evaluate the analgesic contribution of intravenously administered lidocaine and to correlate it with blood levels of the drug. In a double-blind manner, 14 healthy male volunteers received saline solution or lidocaine, 0.2 per cent, at three increasingly greater rates of infusion on two separate days. Experimental pain was produced by means of the submaximal tourniquet-induced ischemia test of Beecher and Smith. The times to the onset of ischemic (threshold) and unbearable (tolerance) pain were recorded for three control trials to two tests for the same end points during each infusion rate. Between the two ischemic trials, while the test solution continued to be infused, venous blood samples were drawn and analyzed for lidocaine by gas chromatography. No statistically significant difference in analgesia between the control and lidocaine values for threshold or tolerance was observed at blood levels from 1 to 3 μg/ml. The data suggest that lidocaine at these blood levels produces sedation but not analgesia.

Stability of self-report measures of improvement in chronic pain: A five-year follow-up

Abstract Seventy patients with chronic low‐back pain not due to malignancy returned a questionnaire assessing functional status 5 years following treatment with epidural or subarachnoid nerve blocks. One hundred fifty‐one patients had been surveyed 3 years earlier in an initial follow‐up. The respondents to the present survey were older and more able to bend and took more medication for pain than non‐respondents. The results revealed a tendency for gender‐associated differences in improvement noted in the initial survey to be maintained, with women showing greater absolute improvement than men, particularly in vocational abilities. Men were somewhat more improved as a group on the current follow‐up than on the initial follow‐up. The use of medication for pain remained generally unchanged over time, but the number of respondents reporting the need for additional surgical treatments declined. The results were seen as indicating the need for using multiple, functional criteria in assessing response to treatment, including both global pain ratings and functional‐behavioral measures of improvement.

Treatment of bladder pain with transsacral nerve block.

Fifteen patients with bladder spasticity and pain of three different etiologies were referred to the pain clinic by urologic specialists. These patients were refractory to all prior methods of treatment, excluding major surgical procedures. In a prospective study started in 1976, these patients were treated with transsacral nerve blocks using 0.25% bupivacaine and, in most cases, subsequent 6% aqueous phenol at the right S-3 ventral foramen. If indicated, transsacral nerve blocks were performed at other levels, as described in the text. Of the patients studied 53% have had significant or complete relief of pain for an average of 26.5 months. The associated morbidity was negligible and there was no mortality. This is in contrast to the morbidity and mortality associated with some major surgical “curative” procedures. The technique is proposed as a successful and economical approach to treatment that can be managed on an outpatient basis.

First rib palpation: a safer, easier technique for supraclavicular brachial plexus block.

The supraclavicular approach to local anesthetic blockade of the brachial plexus offers several advantages over other approaches. It has a high success rate and rapid onset of action (1). Compared with the axillary approach, it provides more complete anesthesia of the plexus, particularly the axillary and musculocutaneous nerves, and does not require abduction of the arm to perform. The interscalene approach is complicated by a higher incidence of injection into epidural or subarachnoid spaces or into the vertebral artery. It also is relatively difficult to master (1). The most significant problem that has prevented supraclavicular block from achieving widespread use has been pneumothorax, a complication that has a reported incidence of 0.6 to 5.0% (1). We describe a simple technique utilizing palpation of the first rib to improve the ease of supraclavicular brachial plexus block, which also should decrease the potential of lung injury.