Regional blockade in patients with a history of a seizure disorder.

BACKGROUND: Systemic local anesthetic toxicity is a potential complication in patients undergoing regional anesthesia, particularly during procedures requiring large doses of local anesthetic, such as epidurals, caudals, and peripheral nerve blocks. It is unknown whether patients with a history of a seizure disorder are at an increased risk of central nervous system toxicity (seizures) after local anesthetic administration. METHODS: We retrospectively reviewed the medical records of all patients with documented history of a seizure disorder who underwent epidural, caudal, or peripheral nerve block from January 1, 1988 to December 31, 2001. Patient demographics, character of the seizure disorder, details of the regional procedure, and seizure activity in the perioperative period were recorded. The rate of seizure due to local anesthetic toxicity per 10,000 anesthetics was estimated using a point estimate and corresponding 95% confidence interval (CI). RESULTS: During the 14-yr study period, 411 procedures in 335 patients with a seizure disorder were identified. Twenty-four patients experienced postoperative seizure activity. The timing of the most recent (preoperative) seizure was found to be significantly related to the likelihood of experiencing a postoperative seizure (P < 0.001). Based on the extended time interval between local anesthetic injection and/or termination of the infusion and the event, it was determined that the regional anesthetic was neither the primary etiology nor a contributing factor for the seizure in 19 of the 24 patients. In the remaining five patients, perioperative seizure activity was characteristic of their usual seizures. Although unlikely to be the cause of the seizure, local anesthetic toxicity could not be absolutely excluded as a contributing factor to the event in these five patients. Assuming that none of the seizures was related to local anesthetic toxicity the estimated incidence is 0 per 10,000 (95% CI 0-89 per 10,000). Conversely, if the seizures were related to local anesthetic toxicity in the five cases, the incidence is increased to 120 per 10,000 (95% CI 40-280 per 10,000). CONCLUSIONS: We conclude that majority of seizures occurring in the perioperative period in patients with a preexisting seizure disorder are likely related to the patient's underlying condition and that regional anesthesia in these patients is not contraindicated. Furthermore, because the likelihood of a postoperative seizure is increased in patients with a recent seizure, it is essential to be prepared to treat seizure activity, regardless of the anesthetic and analgesic technique.

The canine factor VIII 3'-untranslated region and a concatemeric hepatocyte nuclear factor 1 regulatory element enhance factor VIII transgene expression in vivo.

If gene therapy is to be an effective treatment modality for hemophilia A, therapeutic levels and tissue-restricted expression of factor VIII (FVIII) must be achieved through optimization of transgene expression. To this end, we incorporated three types of sequence elements into a canine B domain-deleted FVIII transgene cassette and individually evaluated their effect on FVIII transgene expression. Functional FVIII activity was initially assessed in vitro and hydrodynamic injection of the different transgene constructs into mice was subsequently used as a model to compare in vivo expression of the various modified transgenes. Our results demonstrate that in vitro transgene expression is, in these studies, not a good predictor of in vivo transgene performance. In vivo analysis of a hybrid tissue-restricted promoter element, consisting of a concatemer of five hepatocyte nuclear factor 1 (HNF-1) consensus-binding motifs juxtaposed to the human FVIII proximal promoter, indicates that it is as efficient at mediating expression of the FVIII protein as the cytomegalovirus promoter. Addition of the full-length canine FVIII 3'-UTR also enhances transgene expression of FVIII in vivo. Sequence analysis of the canine FVIII 3'-UTR and human FVIII 3'-UTR indicates that the former lacks instability sequences and may therefore be more effective in stabilizing FVIII mRNA. Subsequent inclusion of FVIII introns 16 and 17 into the natural locations of the transgene disrupted mRNA processing and abolished expression of the FVIII protein. Introduction of intron 17 proximal to the FVIII cDNA did not enhance in vivo expression of canine FVIII from the transgene.

Ultrasound machine comparison: an evaluation of ergonomic design, data management, ease of use, and image quality.

BACKGROUND AND OBJECTIVES: The use of ultrasound technology for vascular access and regional anesthesia is gaining widespread acceptance among anesthesia providers. As a result, many group practices and medical institutions are considering purchasing ultrasound equipment. Currently, comparative information regarding the ergonomic design, physical and adjustable features, data management, ease of use, cost, and image quality of various ultrasound machines is not available. The primary goal of this investigation was to develop an objective process of evaluating ultrasound equipment before purchase. The process of evaluation used in the current investigation may be used when comparing a variety of medical technologies. METHODS: A randomized, side-by-side comparative evaluation of 7 different ultrasound machine models was performed. Sixteen resident physicians without prior ultrasound experience (inexperienced providers) completed a formal evaluation of each machine model after performing a standardized machine configuration and performance checklist. Inexperienced providers and 10 faculty members experienced in ultrasound-guided regional anesthesia evaluated the image quality of 2 standardized images acquired from each machine model. RESULTS: Overall, evaluators rated questions on the machine evaluation form as "very good" or "outstanding" 70% or more of the time for all machine models. The largest, most complex ultrasound machine was rated as having the best image quality by both inexperienced and experienced providers. Ultrasound machine models with the simplest ergonomic design and user interface were rated highest by inexperienced study participants. CONCLUSIONS: Anesthesia providers considering an ultrasound equipment purchase should objectively evaluate machine models that have features most important to their own clinical practice. Ergonomic design, physical and adjustable features, data management, ease of use, image quality, and cost are important features to consider when evaluating an ultrasound machine.