Diagnostic accuracy of exercise electrocardiogram in patients with left anterior hemi-block

BACKGROUND: Left anterior hemiblock (LAHB) is the most frequent conduction abnormality, but its impact on the diagnostic accuracy of the exercise ECG has not been studied. The aim of our study was to determine the diagnostic accuracy of ST depression for predicting ischaemia in the presence of LAHB. PATIENTS: Consecutive patients with known or suspected coronary heart disease undergoing exercise ECG and 99mTc-sestamibi single photon emission computed tomography (SPECT) were included in the analysis. Patients with left bundle branch block, with changes in QRS morphology related to myocardial infarction, and patients who had undergone pharmacological stress testing were excluded. RESULTS: Of 1532 patients assessed, 567 patients qualified for the analysis. In 69 patients with LAHB, ECG stress testing had lower sensitivity (38% vs 86%) and lower negative predictive value (82% vs 92%) than in patients with normal baseline ECG. The reduction of sensitivity appeared to be similar in patients with isolated LAHB (n=43), in patients with right bundle branch block (n=39), and with bifascicular block (n=26). In contrast, the positive predictive value of the test was excellent. CONCLUSION: The diagnostic accuracy of the exercise ECG for prediction of ischaemia is reduced in patients with LAHB.

Standardization of infusion solutions to reduce the risk of incompatibility

PURPOSE: Although critically ill patients usually have various central intravenous (i.v.) lines, numerous drugs have to be infused simultaneously through the same lines. This can result in potentially harmful in-line incompatibility that can cause decreased drug effectiveness or increased microparticle load. To minimize the risk of these medication errors at an anesthesia intensive care unit (ICU), the preparation and administration of continuously infused drugs were standardized and the practicability in daily clinical routine was evaluated. SUMMARY: The concentration and diluent of continuously administered i.v. drugs were standardized. The drugs were grouped according to pH, medical indication, and chemical structure. The ICU staff decided to use multilumen central venous catheters, and each group of drugs was assigned to one lumen. Only drugs that belonged to the same group were infused simultaneously through the same lumen; therefore, intragroup incompatibilities had to be excluded before establishing the new drug administration plan at the ICU. The visual compatibility of 115 clinically reasonable intragroup drug mixtures was investigated. All drug combinations were compatible for six hours except mixtures containing thiopental, which was reassigned to a single-line use. In the following year, the practicability of this drug administration plan was evaluated. No deviations were found in the compliance of the staff prescribing and preparing only standardized concentrations and diluents. Further research to investigate the chemical compatibility of the drugs in these multiple mixtures will follow. CONCLUSION: A project intended to avoid incompatibility among i.v. drugs infused in the intensive care setting included steps to standardize solutions and determine which could be given together.

Minimal local anesthetic volume for peripheral nerve block: a new ultrasound-guided, nerve dimension-based method

BACKGROUND AND OBJECTIVES: Nerve blocks using local anesthetics are widely used. High volumes are usually injected, which may predispose patients to associated adverse events. Introduction of ultrasound guidance facilitates the reduction of volume, but the minimal effective volume is unknown. In this study, we estimated the 50% effective dose (ED50) and 95% effective dose (ED95) volume of 1% mepivacaine relative to the cross-sectional area of the nerve for an adequate sensory block. METHODS: To reduce the number of healthy volunteers, we used a volume reduction protocol using the up-and-down procedure according to the Dixon average method. The ulnar nerve was scanned at the proximal forearm, and the cross-sectional area was measured by ultrasound. In the first volunteer, a volume of 0.4 mL/mm of nerve cross-sectional area was injected under ultrasound guidance in close proximity to and around the nerve using a multiple injection technique. The volume in the next volunteer was reduced by 0.04 mL/mm in case of complete blockade and augmented by the same amount in case of incomplete sensory blockade within 20 mins. After 3 up-and-down cycles, ED50 and ED95 were estimated. Volunteers and physicians performing the block were blinded to the volume used. RESULTS: A total 17 of volunteers were investigated. The ED50 volume was 0.08 mL/mm (SD, 0.01 mL/mm), and the ED95 volume was 0.11 mL/mm (SD, 0.03 mL/mm). The mean cross-sectional area of the nerves was 6.2 mm (1.0 mm). CONCLUSIONS: Based on the ultrasound measured cross-sectional area and using ultrasound guidance, a mean volume of 0.7 mL represents the ED95 dose of 1% mepivacaine to block the ulnar nerve at the proximal forearm.

Ultrasound-guided pudendal nerve block in cats undergoing perineal urethrostomy: a prospective, randomised, investigator-blind, placebo-controlled clinical trial

The objective of this study was to evaluate the clinical usefulness, in terms of analgesic efficacy and safety, of ultrasound-guided pudendal nerve block performed with bupivacaine in cats undergoing perineal urethrostomy. Eighteen client-owned male cats scheduled for perineal urethrostomy were enrolled in the study and assigned to one of two treatment groups. The pudendal nerve block was performed under general anaesthesia as described elsewhere, with 0.3 ml/kg of either saline (group C) or 0.5% bupivacaine (group B) - the total injection volume being split equally on the two sites of injection (left and right). Intra-operatively, assessment of nociception was based on the rescue analgesics requirement, as well as on the evaluation of changes in physiological parameters in comparison with the baseline values. Post-operative pain assessment was performed using three different pain scales at recovery and then 1, 2 and 3 h after recovery. Cats in group B showed lower heart rates and required fewer analgesics during surgery than group C. Post-operatively, group B had lower pain scores and needed less rescue buprenorphine than group C. Iatrogenic block-related complications were not observed. In conclusion, the ultrasound-guided pudendal nerve block can be considered clinically useful in feline medicine as it provides reliable analgesia in cats undergoing perineal urethrostomy.

An urn-based Bayesian block bootstrap

Block bootstrap has been introduced in the literature for resampling dependent data, i.e. stationary processes. One of the main assumptions in block bootstrapping is that the blocks of observations are exchangeable, i.e. their joint distribution is immune to permutations. In this paper we propose a new Bayesian approach to block bootstrapping, starting from the construction of exchangeable blocks. Our sampling mechanism is based on a particular class of reinforced urn processes

Association of congenital, diffuse electrical disease in children with normal heart: sick sinus syndrome, intraventricular conduction block, and monomorphic ventricular tachycardia.

INTRODUCTION Rhythm disturbances in children with structurally normal hearts are usually associated with abnormalities in cardiac ion channels. The phenotypic expression of these abnormalities ("channelopathies") includes: long and short QT syndromes, Brugada syndrome, congenital sick sinus syndrome, catecholaminergic polymorphic ventricular tachycardia, Lènegre-Lev disease, and/or different degrees of cardiac conduction disease. METHODS The study group consisted of three male patients with sick sinus syndrome, intraventricular conduction disease, and monomorphic sustained ventricular tachycardia. Clinical data and results of electrocardiography, Holter monitoring, electrophysiology, and echocardiography are described. RESULTS In all patients, the ECG during sinus rhythm showed right bundle branch block and long QT intervals. First-degree AV block was documented in two subjects, and J point elevation in one. A pacemaker was implanted in all cases due to symptomatic bradycardia (sick sinus syndrome). Atrial tachyarryhthmias were observed in two patients. The common characteristic ventricular arrhythmia was a monomorphic sustained ventricular tachycardia, inducible with ventricular stimulation and sensitive to lidocaine. In one patient, radiofrequency catheter ablation was successfully performed. No structural abnormalities were found in echocardiography in the study group. CONCLUSION Common clinical and ECG features suggest a common pathophysiology in this group of patients with congenital severe electrical disease.