Lower extremity radicular pain after prophylactic intrathecal saline injection through a subarachnoid catheter following accidental dural puncture

We describe a case in which severe lower extremity radicular pain occurred after administration of 0.9% saline into the subarachnoid space through a catheter that had been left for 20 h following inadvertent dural puncture in an obstetric patient. A 42-year-old (G8P7) woman was admitted for repeat cesarean delivery. Accidental dural puncture occurred during epidural placement. Following a slow 10-mL intrathecal injection of 0.9% normal saline an epidural catheter was advanced into the subarachnoid space. Spinal anesthesia was used for cesarean delivery and the subarachnoid catheter was kept in place for 20 h. Before catheter removal, an additional 10 mL of 0.9% saline was slowly administered into the intrathecal space. Almost instantly, the patient complained of back pain that progressed to lower extremity radicular pain and paresthesia; symptoms began to resolve after 10 min. Subsequently, the patient developed a postdural puncture headache that persisted for three days. The patient's radiculitis and paresthesia likely resulted from an acute increase in intrathecal pressure after saline administration or from direct catheter irritation. Although both intrathecal saline administration and subarachnoid catheter placement have been previously proposed as ways to prevent postdural puncture headache, their efficacy remains controversial, and we advise caution with these techniques.

A noninvasive method in the differential diagnosis of vecuronium-induced and magnesium-induced protracted neuromuscular block in a severely preeclamptic patient

The occurrence of neuromuscular blockade and the resulting potentiation of muscle relaxants during magnesium sulfate (MgSO4) administration is well known. However, a method to differentiate the neuromuscular block induced by magnesium from that induced by curariform nondepolarizing muscle relaxant in the clinical setting has never been reported. We report a case in which the duration of action of 1 mg of vecuronium lasted 4 hours in a patient with severe preeclampsia whose serum magnesium level was in the therapeutic range. We believe this is a remarkable potentiation on record in the literature. We also describe a new, noninvasive method to assess magnesium-induced neuromuscular block when curariform muscle relaxant was given simultaneously.

Electromyographic and mechanomyographic characteristics of neuromuscular block by magnesium sulphate in the pig

In spite of its well known propensity to cause accidental paralysis by a specific mechanism of action, Mg(2+)-induced neuromuscular block has not been examined systematically for its characteristics of muscle response to nerve stimulation. We examined in seven anaesthetized domestic pigs the mechanomyographic (MMG) and neurally evoked compound electromyographic (ncEMG, EMG) responses of the tibialis anterior muscle to stimulation of its motor nerve, at baseline and during three levels of neuromuscular block induced by infusion of MgSO4 (at approximately 25%, 50% and 75% depression of the 0.1-Hz EMG). We observed that: at 0.1 Hz, the MMG tended to be more depressed than the EMG; the train-of-four (2 Hz) was essentially non-fading; the tetanic force (50 Hz) showed tetanic ascent instead of tetanic fade and reached its baseline control value at 5 s in spite of depression of the twitch; the EMG counterpart of the tetanus showed escalation of the train of ncEMG, so that the fourth ncEMG was much greater than the first; and the post-tetanic twitch was also relatively spared from Mg(2+)-induced neuromuscular block. Sparing of the tetanus and post-tetanic twitch resulted in large gains in the tetanus:twitch ratio and the post-:pre-tetanic twitch ratio, which increased at the 75% level of depression from 2.8 (SD 0.7) to 11.5 (4.0), and from 1.5 (0.3) to 4.6 (1.4) (P < 0.01), respectively. These characteristics of neuromuscular block by Mg2+ reflect its prejunctional mechanism of action by depression of transmitter release.

A clinical assessment of desflurane anaesthesia and comparison with isoflurane

In 48 randomly assigned ASA I adult patients undergoing elective orthopaedic procedures, we compared the pharmacodynamics of desflurane (DF) and isoflurane (IF), and their pharmacokinetics during rapid induction of deep anaesthesia (via face mask, to 1.5-2 MAC, after thiopentone), maintenance of anaesthesia at 1.25 MAC, and emergence therefrom. During induction, laryngeal reactions ranging from mild crowing to laryngospasm occurred more frequently with DF than with IF (15/24 DF, 5/24 IF; P < 0.05) and was more severe (9/24 DF, 1/24 IF, excluding the mildest form, P < 0.05). As a result, induction of anaesthesia was not accomplished faster with DF, in spite of a faster equilibration between exhaled and inhaled concentrations. Emergence from DF was more rapid and less complicated by delirium. Pharmacokinetically, the exhaled concentration of DF reached 90% of the inhaled concentration within five minutes of induction, whereas that of IF lagged behind and remained 25% below the inhaled concentration (1 vs 1.34 +/- 0.05) even one hour after induction. Premature ventricular contractions did not occur in any patient even during periods of difficulty with the airway and oxygen desaturation. It is concluded that DF is a safe anaesthetic, pharmacokinetically superior to IF but clinically inferior for induction of anaesthesia via a face mask. Because of the fast equilibration, the exhaled concentration of DF can be controlled more precisely by the dial setting of the vaporiser.

Desflurane potentiates atracurium in humans: a comparative study with isoflurane

STUDY OBJECTIVE

(1) To evaluate the neuromuscular effects of desflurane and its interactions with atracurium and (2) to compare desflurane and isoflurane in these effects.

DESIGN

Sequential entry of informed and consenting patients randomly assigned to receive desflurane (n = 25) or isoflurane (n = 25).

SETTING

Operating suite of a county-university medical center.

PATIENTS

Fifty adults, ASA physical status I, undergoing elective orthopedic surgery.

INTERVENTIONS

Following establishment of steady desflurane or isoflurane anesthesia, at 1.25 minimum alveolar concentration (MAC) exhaled for 15 minutes, a randomly predetermined dose of atracurium (0.05, 0.1, or 0.15 mg/kg) was injected intravenously (IV). At the end of surgery, neostigmine 0.04 mg/kg IV was given to reverse the residual block. The neuromuscular effects of desflurane or isoflurane alone, and the dose-response relationship, time course, and reversibility of the neuromuscular effects of atracurium with either anesthetic, were examined in detail and compared using electromyographic quantification of the response of the first dorsal interosseous muscle to train-of-four (TOF) stimulation of the ulnar nerve.

MEASUREMENTS AND MAIN RESULTS

TOF fade and depression of the first response (T1) of the TOF were measured in response to desflurane or isoflurane, atracurium, and neostigmine. Desflurane caused more TOF fade than isoflurane prior to atracurium administration. The TOF ratios were 0.91 +/- 0.02 and 0.98 +/- 0.01, respectively (p < 0.05). For other measured neuromuscular parameters, atracurium-induced depression tended to be greater in the presence of desflurane than in the presence of isoflurane, but none of the measured differences reached the statistical significance level of p < 0.05. The ED50, ED95, and 25-75% recovery index of atracurium were 0.038 mg/kg (95% confidence level; range 0.030 to 0.047 mg/kg), 0.11 mg/kg (0.095 to 0.14 mg/kg), and 31 +/- 4 minutes (means +/- SEM) with desflurane anesthesia, versus 0.043 mg/kg (0.035 to 0.052 mg/kg), 0.13 mg/kg (0.11 to 0.16 mg/kg), and 23 +/- 4 minutes with isoflurane anesthesia (p = 0.1-0.2). Continuation of either anesthetic at 1.25 MAC prevented complete recovery of neuromuscular functions spontaneously or following neostigmine 0.04 mg/kg.

CONCLUSION

In ASA physical status I adults, 9% desflurane has neuromuscular effects equal to or slightly in excess of those of 1.6% isoflurane.

Recovery of cognitive functions after anaesthesia with desflurane or isoflurane and nitrous oxide

We studied recovery in 25 adult patients, ASA I, undergoing elective orthopaedic procedures after anaesthesia with 0.65 MAC desflurane (n = 16) or isoflurane (n = 9) with 60% nitrous oxide in oxygen. Early emergence from anaesthesia was assessed in the operating room by measuring time to spontaneous movement, cough, response to painful pinch, tracheal extubation, opening of the eyes and stating correct age, name and body parts. The return of cognitive functions in the late recovery phase was assessed in the post-anaesthesia care unit (PACU) by post-anaesthesia recovery scores (PARS), the Trieger dot test (TDT), and the digit substitution test (DST). In the early recovery phase, time to tracheal extubation, opening eyes, telling correct name, age and body parts occurred significantly faster in the desflurane group than in the isoflurane group (P < 0.05). The mean "triple orientation" time (to name, age, body parts) was 10.9 (SEM 0.9) min for desflurane, compared with 18.6 (2.5) min for isoflurane (P < 0.01). In the late recovery phase, desflurane patients had significantly greater PARS, more correct responses to the DST and fewer error responses to the TDT. Recovery times were not increased by increased duration of desflurane anaesthesia. The desflurane patients showed no delirium, minimal sedation and less shivering during the entire postoperative course. We conclude that desflurane anaesthesia was superior to isoflurane anaesthesia, not only in emergence, but also in the recovery of cognitive functions.

Neuromuscular blocking effect and placental gradient of pipecuronium bromide in elective caesarean section

We studied the suitability of pipecuronium for maintenance of neuromuscular block during 20 elective Caesarean sections under light general anaesthesia with a rapid-sequence technique facilitated by i.v. suxamethonium 0.6-0.8 mg kg-1. An initial dose of 0.035 mg kg-1 or 0.05 mg kg-1 of pipecuronium provided satisfactory relaxation of similar speed of onset (3.1 +/- 0.3 vs 3.8 +/- 0.6 min, p = 0.25); however the higher dose had a significantly longer duration of action than the lower dose (from injection to recovery to 20% of baseline 13.1 +/- 1.8 vs 39.3 +/- 6.9 min, p < 0.05). A spontaneous recovery of the T1 twitch of the train-of-four to 25% of baseline (residual block 75%) assured rapid antagonism of the residual block with either edrophonium 0.5 mg kg-1 or neostigmine 0.04 mg kg-1. A residual block greater than 80% depression of T1 markedly prolonged the time taken to achieve a satisfactory reversal. Pipecuronium had negligible cardiovascular effects and placental transfer. It had no observable effect on the newborn. In spite of some advantages, we conclude that pipecuronium is a suitable alternative during Caesarean section only when used judiciously in small doses for maintenance of neuromuscular block and recommend that the initial dose be no greater than 0.035 mg kg-1.

DNA adducts in bronchial biopsies

To investigate the feasibility of measuring DNA-carcinogen adducts in the lungs of non-surgical patients, endobronchial biopsies were obtained from 78 patients undergoing routine diagnostic bronchoscopy. Lung cancer was present in 37 (47%) of the patients. DNA was isolated from the tissues and analyzed by HPLC- or nuclease-PI-enriched 32P-postlabelling, using procedures selective for aromatic adducts. Chromatograms from all 28 current smokers showed a distinctive diagonal adduct zone which was present in only 24 of 40 ex-smokers and 4 of 10 lifetime non-smokers. Adduct levels and chromatographic patterns were similar in bronchial tissue from different lobes of the lung, in bronchial and alveolar tissue, and in tumor and non-tumor bronchial tissue taken from the same subject. Bronchial DNA adduct levels were strongly associated with cigarette smoking status and dropped rapidly after smoking ceased. Higher levels of DNA adducts seen in the lung-cancer patients were mainly due to cigarette smoking. Frequent alcohol intake was the only dietary factor associated with higher levels of bronchial DNA adducts. We conclude that the level of bronchial DNA adducts is strongly associated with cigarette-smoking history and with alcohol intake, but is not associated with lung cancer independently from its relation to smoking. The results indicate the feasibility of using 32P-postlabelling to detect and quantitate genetic damage in bronchial biopsy specimens.