Minimum effective volume of local anesthetic in peribulbar block: does it differ with the eyeball axial length?

BACKGROUND: Peribulbar Anesthesia (PBA) is a relatively safe method for cataract surgery. The anesthetic volume should be adjusted according to the axial eyeball length. Thus, using Minimum Effective Volume (MEV) of local anesthetic helps avoiding unnecessary volumes, preventing increases in intra-ocular pressure, and producing satisfactory conditions for cataract surgery. This study aims to determine the MEV90 of local anesthetics in relation to eye globe axial length in peribulbar blocks for cataract surgery. METHODS: Patients scheduled for cataract extraction under local anesthesia were divided according to their axial eyeball length; Group 1 included those with axial length from 22 to 24 mm, Group 2 included patients with axial length from 24.1 to 26 mm. The initial volume used was 7 mL of a solution of bupivacaine 0.5% (3 mL) + lidocaine 2% (3 mL) + hyaluronidase 150 IU (1 mL). The subsequent volumes were dependent on the response of the previous patient, by using a Bias Coin Design (BCD) and Up and Down Method (UDM) for MEV-90 determination. RESULTS: The study was concluded with 119 patients. Sixteen patients needed supplemental volume of local anesthetic in Group 1 and thirteen in Group 2. The MEV90 for Group 1 was approximately 5.82 mL (95% CI 5.6 to 5.87 mL) and 5.45 mL for Group 2 (95% CI 5.38 to 5.91 mL). No major complications were noted. There was a negative correlation between the effective volume of LA and eye globe axial length in both groups (p = 0.001). CONCLUSION: The MEV90 of local anesthetics for peribulbar block show a strong and inverse correlation with eye globe axial length. This may help achieving an effective block with minimum complications.

Value of Coronary Calcium Scoring in Symptomatic and Asymptomatic Coronary Artery Disease Patients.

AIM AND OBJECTIVE: The study aimed to estimate the relationship between Coronary Calcium Scoring (CCS) and the presence of different degrees of obstructive coronary artery disease (CAD) to avoid unnecessary examinations and hence unnecessary radiation exposure and contrast injection. BACKGROUND: Coronary Calcium Scoring (CCS) is a test that uses x-ray equipment to produce pictures of the coronary arteries to determine the degree of its narrowing by the build-up of calcified plaques. Despite the lack of definitive data linking ionizing radiation with cancer, the American Heart Association supports widely that practitioners of Computed tomography Coronary Angiography (CTCA) should keep "patient radiation doses as low as reasonably achievable but consistent with obtaining the desired medical information". METHODS: Data obtained from 275 CTCA examinations were reviewed. Radiation effective doses were estimated for both CCS and CTCA, and measures to keep them as low as possible were presented. CCS and Framingham risk estimates were compared to obtain the final results of CTCA to detect sensitivity and specificity of each one in detecting obstructive lesions. RESULTS: CCS is a strong discriminator for obstructive CAD with high sensitivity and specificity and correlates well with the degree of obstruction even more than Framingham risk estimate, which has high sensitivity and low specificity. CONCLUSION: CCS helps to reduce the effective radiation dose if properly evaluated to skip unnecessary CTCA if obstructive lesions are unlikely, and this as a test does not use contrast material, thus harmful effect on the kidney will be avoided as most of the coronary atherosclerotic patients have renal problems.