Radiation dose difference between state of the art myocardial perfusion scintigraphy and computed tomography coronary angiography in patients undergoing evaluation for suspected coronary artery disease.

Minimisation of radiation exposure with cardiac imaging reduces the potential of secondary side effects. Radiation exposure from myocardial perfusion scintigraphy and computed tomography coronary angiography (CTCA) was compared. Overall doses were low with both modalities. Doses were lower in the CTCA group, but by only a small difference of 1.1 mSv. Radiation exposure should not be the primary consideration when choosing between these two modalities.

Comparison of 4% articaine and 0.5% levobupivacaine/2% lidocaine mixture for sub-Tenon's anaesthesia in phacoemulsification cataract surgery: a randomised controlled trial.

BACKGROUND/AIMS: [corrected] The aim of this study was to compare the efficacy and safety of 4% articaine with a mixture containing equal volumes of 2% lidocaine and 0.5% levobupivacaine without hyaluronidase for sub-Tenon's anaesthesia in phacoemulsification cataract surgery. METHODS: The study was a prospective, randomised double-masked clinical trial of 65 patients allocated to receive either 4% articaine or a mixture containing equal parts of 2% lidocaine and 0.5% levobupivacaine. All patients had pre- and postoperative Hess charting to document ocular motility dysfunction. Ocular and eyelid movements were scored at 2 min intervals from 2 to 10 min after injection of the anaesthetic agent, and at the end of surgery. Complications related to injection, including pain, chemosis and subconjunctival haemorrhage, were recorded. Patients rated pain (none/mild/moderate/severe) during surgery. The operating surgeon masked to the anaesthetic agent assessed proptosis/chemosis at the start of the operation and the degree of ocular akinesia and analgesia at the end of surgery. RESULTS: The articaine group demonstrated a rapid onset of ocular akinesia with a mean time to readiness for surgery (achieving a score of

The safety and tolerability of adenosine in patients with obstructive airways disease.

Controversy exists regarding the safety of intravenous dipyridamole in patients with severe chronic obstructive pulmonary disease (COPD), and it is contraindicated in patients with asthma. There is currently little published literature on the safety of adenosine in patients with airways disease, despite potential advantages over dipyridamole with respect to side effects. We studied 46 consecutive patients with a history of COPD or asthma undergoing adenosine stress myocardial perfusion scintigraphy. Spirometry with measurement of forced expiratory volume in 1 s (FEV(1)), forced vital capacity, peak expiratory flow rate and a repeat FEV(1) postinhaled bronchodilator in all those with a history of asthma was performed prior to receiving intravenous adenosine 140 mg/kg/min for 4 min. The cohort exhibited significant airflow limitation on spirometry (see Table 1), however the majority of patients (24/46) did not experience any dyspnoea or chest pain during adenosine infusion. Fourteen patients experienced chest discomfort during adenosine, and 9 complained of dyspnoea. No patient required aminophylline or resuscitative measures. In our cohort of patients with a history of COPD, asthma or both who demonstrated impaired lung function on spirometry, adenosine was safe and well tolerated.

Comparison of articaine and bupivacaine/lidocaine for sub-Tenon's anaesthesia in cataract extraction.

BACKGROUND: Articaine is the most widely used local anaesthetic for dental anaesthesia in Germany, Italy and The Netherlands and has recently been introduced and licensed for dental use in the UK. We have previously shown articaine to be superior to a standard mixture of bupivacaine 0.5%/lidocaine 2% for peribulbar anaesthesia. Sub-Tenon's anaesthesia arguably provides a safer method of anaesthetic delivery for cataract surgery. A blunt cannula is used in this technique, thus greatly reducing the risk of globe perforation, intrathecal injection and sight-threatening periocular haemorrhage. METHODS: We compared articaine and bupivacaine/lidocaine for sub-Tenon's anaesthesia in cataract surgery. RESULTS: Sub-Tenon's anaesthesia using articaine 2% resulted in a more rapid onset of motor block compared with a bupivacaine/lidocaine (P=0.0076). Ocular movement scores were significantly lower from 2 min after injection until the end of surgery (P=0.031 ANOVA). CONCLUSION: Articaine 2% is safe and effective for sub-Tenon's anaesthesia and is a suitable alternative to the traditional bupivacaine 0.5%/lidocaine 2% mixture.

Comparison of articaine and bupivacaine/lidocaine for peribulbar anaesthesia by inferotemporal injection.

BACKGROUND: Articaine is a novel amide local anaesthetic with a shorter duration of action than prilocaine. METHODS: In a randomized, double-blind study we compared the efficacy of 2% articaine with epinephrine 1:200,000 with a mixture of 0.5% bupivacaine and 2% lidocaine with epinephrine 1:200,000 for peribulbar anaesthesia in cataract surgery using a single inferotemporal injection. Eighty-two patients were randomly allocated to one of two groups to receive peribulbar anaesthesia with 6-7 ml of articaine or a bupivacaine/lidocaine mixture. Both solutions contained hyaluronidase 30 iu ml(-1). Ocular movement was scored at 2 min intervals up to 10 min, at the end of surgery and at time of discharge from hospital. Time to readiness for surgery and any complications (proptosis, chemosis, pain) were recorded. RESULTS: The articaine group demonstrated a rapid onset of peribulbar block with mean time (SD) to readiness for surgery of 4.2 (4.5) min compared with 7.2 (5.7) min in the bupivacaine/lidocaine group (P=0.0095). The block obtained in the articaine group was dense with eye movement scores at 2, 4, 6, 8 and 10 min all significantly reduced (P<0.01 at each interval). There was also a faster offset of the block in the articaine group (P=0.0009). There was no difference in incidence of minor complications between the groups. CONCLUSIONS: Two per cent articaine is safe and effective for peribulbar anaesthesia by inferotemporal injection and is a suitable alternative to the traditional mixture of 0.5% bupivacaine and 2% lidocaine.

Comparison of articaine and bupivacaine/lidocaine for single medial canthus peribulbar anaesthesia.

In a single-centre, randomized, double-blind study, we compared the efficacy of 2% articaine with that of a mixture of 0.5% bupivacaine and 2% lidocaine for peribulbar anaesthesia in cataract surgery, using a single medial canthus injection technique. Eighty-two patients were allocated randomly to receive 7-9 ml of a mixture of 0.5% bupivacaine and 2% lidocaine or an equal volume of 2% articaine with 1:200,000 epinephrine. Hyaluronidase 30 iu ml(-1) was added to both solutions. The degree of akinesia was scored 1, 5 and 10 min after the block, at the end of surgery and at discharge from the day case unit. Primary outcome measures were the difference in ocular movement scores 5 min after block and the need for supplementary inferolateral injections. There was greater akinesia in the articaine group at 5 min (P=0.01). Ten patients (24%) in the articaine group and 21 patients (51%) in the bupivacaine/lidocaine group required a supplementary injection (P=0.02). The mean (SD) volume of local anaesthetic required to achieve adequate block for surgery was 9.7 (2.1) ml in the articaine group and 11.0 (2.2) ml in the bupivacaine/lidocaine group (P=0.01). There was a faster offset of akinesia after surgery in the articaine group (P=0.01). There were no differences between groups in the incidence of reported pain or of minor complications. In our study, 2% articaine with 1:200,000 epinephrine was safe and efficacious for single medial canthus peribulbar anaesthesia.

Scanning mutagenesis identifies amino acid side chains in transmembrane domain 5 of the M(1) muscarinic receptor that participate in binding the acetyl methyl group of acetylcholine.

The exofacial part of transmembrane domain 5 (TMD 5) of the cationic amine-binding subclass of 7-transmembrane receptors is thought to be important in binding the side chain of the agonist. Residues Ile-188 through Ala-196 in TMD 5 of the M(1) muscarinic acetylcholine receptor (mAChR) have been studied by Cys- and Ala-scanning mutagenesis. The results are consistent with a helical conformation for this sequence. The positively charged sulfhydryl reagent N-trimethyl-2-aminoethyl methanethiosulfonate reacted selectively with Phe-190 --> Cys, Thr-192 --> Cys, and Ala-193 --> Cys, indicating that the face of TMD 5 accessible from the binding site crevice is consistent with a recent model by Baldwin and colleagues of the transmembrane domain of the 7-transmembrane receptors. In contrast, the acetylcholine derivative bromoacetylcholine reacted selectively with Thr-192 --> Cys, which forms the focus of a group of amino acids (Ile-188, Thr-189, Thr-192, Ala-196) whose mutation decreased the binding affinity of the transmitter ACh itself. The center of this patch of residues is offset to one side of the binding pocket, suggesting that a rotation of TMD 5, relative to that implied by the Baldwin model, may be necessary to optimize the anchoring of acetylcholine within the binding site of the M(1) mAChR. An induced rotation of TMD 5 could contribute to the formation of the activated state of the receptor.