Patrick Narchi

Ventilatory effects of premedication with clonidine.

Clonidine has been proposed as a premedication before surgery because of its beneficial effects on hemodynamics, especially in patients with a high cardiovascular risk. However, reports on the effects of clonidine on ventilation are conflicting. Accordingly, eight fasting ASA physical status I volunteers received in a double-blind randomized order 300 μg of oral clonidine, the effects of which were compared with placebo given in a crossover design. Hypotension, bradycardia, and sedation were significantly more profound and of longer duration after clonidine. Clonidine did not decrease minute ventilation more than the placebo, and separate analysis of tidal volume and respiratory rate changes also showed the absence of a significant difference between the two groups. However, clonidine produced episodes of obstructive pattern associated with moderate decreases in oxygen saturation, which were not observed with placebo. We conclude that the potential detrimental effects of these obstructive airway patterns of clonidine should be taken into account when prescribing this drug for premedication.

Ultrasound- or Nerve Stimulation-Guided Wrist Blocks for Carpal Tunnel Release: A Randomized Prospective Comparative Study

Background and Objectives: We hypothesized that ultrasound‐guided wrist blocks may be faster to perform, and may increase success rate, compared with nerve stimulation‐guided wrist blocks. Methods: Sixty patients undergoing ambulatory endoscopic carpal tunnel release were randomly allocated to receive median and ulnar nerve blocks using either sensory‐motor nerve stimulation (n = 30) or ultrasound guidance (n = 30). Four mL of mepivacaine 1.5% was injected around each nerve. Performance time and onset time of complete sensory block were assessed. Results: Median time to perform both median (ultrasound, 55 [48‐60] vs. nerve stimulation, 100 [65‐150] seconds, P = .002) and ulnar (ultrasound, 57 [50‐70] vs. nerve stimulation, 80 [60‐105] seconds, P = .02) nerve blocks were significantly shorter in the ultrasound group. Onset time of complete sensory block in the median (ultrasound, 370 [278‐459] vs. nerve stimulation, 254 [230‐300] seconds, P = .02) and ulnar (ultrasound, 367 [296‐420] vs. nerve stimulation, 241 [210‐300] seconds, P = .01) nerve areas were shorter in the nerve stimulation group. The success rate was 93% in both groups. Conclusions: This randomized prospective study demonstrates that ultrasound‐guided wrist nerve blocks are as efficient as those performed with nerve stimulation.

Ventilatory effects of epidural clonidine during the first 3 hours after caesarean section

Many authors have shown the analgesic efficacy of 150–800 μg of epidural clonidine in the postoperative period. Its use as an analgesic after caesarean section has recently been studied with higher dosages (400–800 μg). Our study aimed at assessing the analgesic and ventilatory effects of two smaller doses of epidural clonidine (150 and 300 μg), which were compared to the effects of 10 mg of parenteral morphine (M) during the first 3 h after caesarean section. The duration of the analgesic effect was longest with 150 μg of epidural clonidine. Arterial blood pressure decreased from 30 min after the injection to the end of the study in both epidural clonidine groups. A marked sedation was observed in patients receiving 300 μg of epidural clonidine and was frequently associated with snoring, obstructive apnoea and episodes of arterial oxygen desaturation. We conclude that 150 μg of epidural clonidine provides better and longer analgesia after caesarean section than 10 mg of parenteral morphine, and seems preferable to higher doses (300 μg) in this setting, since 300 μg of epidural clonidine may produce unacceptable respiratory obstructive disturbances.

Long-term postdural puncture auditory symptoms: effective relief after epidural blood patch.

Spinal anesthesia is followed by a cerebrospinal fluid leakage around the hole made by the spinal needle. Audiometric disturbances are frequent (found in 42% of patients) (l), whereas hearing loss and tinnitus occur in only 0.3%-8% of patients after spinal anesthesia (2,3). Since auditory disturbances are related to the same mechanism as postdural puncture headache (PDPH), it would be logical to suggest the use of an epidural blood patch (EBP) in refractory auditory complaints. We thus report one case of longlasting isolated tinnitus that was dramatically relieved after EBP. A 57.yr-old male presented to an ear, nose, and throat (ENT) surgeon for a history of bilateral tinnitus lasting for 4 years. His symptoms had started 24 h after a diagnostic lumbar puncture that had been ordered for the diagnosis of unexplained depression. Tinnitus was relieved in the supine position only initially, and the patient was obliged to increase the volume of the television and radio, which led to conflict with his spouse. The ENT surgeon sent him to us, after which we performed an EBP with 20 mL of autologous blood. The next day, the patient was symptomless and remained so thereafter. Audiometric testing after spinal anesthesia may reveal hearing loss of lo-40 dB in the low-frequency range, commonly below 1000 Hz. These features are usually transient and disappear within several days (4). Fog et al. (4) showed that the audiometric changes were more frequent after spinal anesthesia with a 22.gauge Quincke needle (93%) than with a 26-gauge Quincke needle (28.5%). As there are reports of improvement of long-lasting PDPH (5) and short-term auditory symptoms with EBP (6), it was logical to suggest the use of EBP in refractory auditory complaints. Recently, Lybecker and Andersen (7) reported a case of a young woman who underwent three EBPs within 5 wk for recurrent PDPH associated with vestibulocochlear disturbances. In conclusion, thorough questioning regarding a past history of spinal puncture should be undertaken by ENT surgeons, neurologists, and general practitioners whenever the diagnosis of hearing loss or tinnitus remains unclear. EBP should be proposed to confirm the etiology of dural puncture and to relieve auditory symptoms, which may last for years.

Lateral approach to the sciatic nerve at the popliteal fossa combined with saphenous nerve block

The lateral approach to the sciatic nerve block at the popliteal level is a recently described, innovative technique. Compared with other approaches, it has the advantage of being performed with the patient supine and of preserving hamstring function. Moreover, a lateral approach rather than a posterior approach at the popliteal fossa reduces the hazard of vascular puncture and improves patients safety. All these advantages should increase the popularity of the block, which currently remains underused by many anesthesiologists. For painful stimuli involving the medial side of the leg, a saphenous nerve block may be combined with the block of the sciatic nerve. This article describes and compares a simple technique using easily identified anatomic landmarks, with more classical approaches.