Validation of a non-invasive pulse CO-oximetry based hemoglobin estimation in normal blood donors.

INTRODUCTION: Non-invasive hemoglobin estimation may increase the recruitment of blood donors. CO-oximetry hemoglobin estimation is a non-invasive method used to estimate the hemoglobin level. The primary objective of this study is to validate the pulse CO-oximetry based hemoglobin estimation in normal blood donors. METHODS: We conducted a prospective observational study on 106 in a tertiary care hospital blood bank over a period of 4 weeks. We performed a Spot Hemoglobin concentration (Sp Hb) using Masimo Pronto-7 Pulse CO-oximetry, and compared it to a venous sample Hb concentration (Reference Hemoglobin; Ref Hb) measured using Abbott CELL-DYN Sapphire hematology analyzer. Age, gender, weight, height, blood pressure and reference hemoglobin were used in the multivariable linear regression model of the difference in measurement. RESULTS: Total of 106 donors (98 males, 8 females) were enrolled with a mean age and Ref Hb of 27 years (SD 6.2; 18-49) and 14.2 g/dL (SD 1.2; 11.5-17) respectively. The mean Sp Hb was 14.4 g/dL (SD 1.2;11.3-16.7). The mean difference between the Sp Hb and Ref Hb was 0.2 g/dL (SD 1.2;-4.5 to 3) with a correlation coefficient of 0.46 (R(2)=21%). In the multivariable model, height (p=0.015) and Hb level (p<0.001) were statistically significant predictors. A strong correlation was found between the two CO-oximetry Hb measurements (coefficient 0.78, R(2)=60%). CONCLUSIONS: Our study validated the use of the CO-oximetry in blood donors. Larger prospective studies are needed to confirm our results.

Correlation of iron overload and glomerular filtration rate estimated by cystatin C in patients with ß-thalassemia major.

Historically, renal involvement has not been a commonly recognized complication in patients with ß-thalassemia major (ß-TM). Herein, we studied the impact of iron overload on glomerular filtration rate (GFR) estimated by cystatin C based GFR (Cyst C eGFR). We enrolled 149 patients with ß-TM in a cross sectional study in a single center in Oman. We investigated the correlation between measurement of serum ferritin and Cyst C eGFR. We used univariable linear regression to study the impact of serum ferritin on Cyst C eGFR and backwards stepwise regression to adjust for potential confounders. We included 78 males and 71 females with a mean age of 17.3 ± 9 years (range 2.5-38.5). Seventeen patients had diabetes mellitus. Patients were taking deferiprone (DFP) and deferoxamine (DFO) (26 patients), DFP (58 patients), deferasirox (DFX) (62 patients) and one patient was taking only DFO. There was a very weak negative linear relationship between serum ferritin and Cyst C eGFR (correlation coefficient -0.25). In the univariable analyses, serum ferritin (p = 0.004), diabetes status (p < 0.001) and chelation therapy (p < 0.001) were statistically significant. In the multivariable model, age (p = 0.033), chelation with DFX (p = 0.05) and diabetes status (p < 0.001) were statistically significant. We found a very weak inverse linear correlation between serum ferritin and Cyst C eGFR. However, when concomitant use of chelation therapy was considered, serum ferritin did not associate with glomerular function. Prospective and larger studies are needed to confirm these findings.

The role of echocardiography in the management of structural valve degeneration of transcatheter valves.

Transcatheter valve implantation in patients with aortic stenosis has evolved as an acceptable alternative to surgical aortic valve replacement in a subset of patients at excessively high risk from surgery. The structural valve degeneration (SVD) is a known phenomenon in catheter-based valves too, which was hitherto seen with surgical bioprosthetic valves. Echocardiography plays a pivotal role not only in early detection but also in the management of SVD of Transcatheter valves. The goal of this report is to agglomerate our experience of an unusual case of SVD of a catheter-based valve implanted inside the bioprosthetic aortic and mitral valve apparatus and its management with aortic and mitral valve replacement with mechanical valve prosthesis.

Ortner's syndrome: Cardiovocal syndrome caused by aortic arch pseudoaneurysm.

72-year-old hypertensive presented with two weeks history of left sided chest pain and hoarseness. Workup demonstrated a pseudoaneurysm in the lesser curvature of the distal aortic arch opposite the origin of the left subclavian artery from a penetrating atherosclerotic ulcer. Following a left carotid-subclavian bypass, endovascular stenting of the aorta was performed excluding the pseudoaneurysm. Patient had excellent angiographic results post-stenting. Follow up at 12 weeks demonstrated complete resolution of his symptoms and good stent position with no endo-leak. Ortner's syndrome describes vocal changes caused by cardiovascular pathology. It should be included in the differential diagnosis of patients with cardiovascular risk factors presenting with hoarseness. This case demonstrates the use of endovascular stents to treat the causative pathology with resolution of symptoms. In expert hands, it represents low risk, minimally invasive therapeutic strategy with excellent early results in patients who are high risk for open procedure.

Combined transcervical and thoracoscopic mediastinal parathyroid adenoma resection.

The routine approach for excision of a parathyroid adenoma is transcervical, but this approach is inadequate when the gland is located in the mediastinum. Traditionally, these cases have required a sternotomy or thoracotomy. We used a combined transcervical and video-assisted thoracoscopic surgery approach to resect a parathyroid adenoma that extended to the middle mediastinum.

Knowledge and Attitudes of Oman Medical Specialty Board Residents towards Evidence-Based Medicine.

OBJECTIVE: This study aims to evaluate the knowledge and attitudes of Oman Medical Specialty Board (OMSB) residents towards Evidence-Based Medicine (EBM). METHODS: This cross sectional study was conducted on all OMSB residents through a self-administered online questionnaire between October 2012 and March 2013. An electronic survey was designed to identify and determine residents' knowledge and attitudes toward the use of EBM. RESULTS: The survey was completed by 93 (21%) OMSB residents, 76 (82%) of whom took part in continuing education courses and 50 (54%) belonged to professional practice-oriented organizations. On average, the residents were reportedly involved in patient care for approximately 70% (Standard Deviation [SD] 17%) of their time, while 14% (SD 12%) participated in research activities. The results showed that 53 respondents (57%) were competent users of medical search engines compared to 23 residents (25%) who rated their skills as neutral. Sixteen percent of the respondents strongly agreed and 46% only agreed that the facility supports the use of current research in practice. Fourteen percent strongly agreed and fifty-three percent only agreed that the foundation of EBM is part of OMSB academic preparation. On the other hand, 17% of the respondents thought that insufficient time is always a barrier against EBM, while another 27% perceived insufficient time as a usual barrier. The lack of information resources was reported to always be a barrier in 11% of the respondents while 32% thought that it usually acts as a barrier. CONCLUSION: Time constraints and skills in EBM were found to be the two major obstacles. This study was, however, limited by the low response rate of the survey; thus larger studies with a previously validated questionnaire should be conducted in the future.

Non-invasive haemoglobin estimation in patients with thalassaemia major.

OBJECTIVES: This study aimed to validate pulse CO-oximetry-based haemoglobin (Hb) estimation in children and adults with thalassaemia major (TM) and to determine the impact of different baseline variables on the accuracy of the estimation. METHODS: This observational study was conducted over a five-week period from March to April 2012. A total of 108 patients with TM attending the daycare thalassaemia centre of a tertiary care hospital in Muscat, Oman, were enrolled. Spot (Sp) Hb measurements were estimated using a Pronto-7(®) pulse CO-oximetry device (Masimo Corp., Irvine, California, USA). These were compared to venous samples of Hb using the CELL-DYN Sapphire Hematology Analyzer (Abbott Diagnostics, Abbott Park, Illinois, USA) to determine the reference (Ref) Hb levels. A multivariable linear regression model was used to assess the impact of baseline variables such as age, gender, weight, height, Ref Hb and blood pressure on the Hb estimations. RESULTS: Of the 108 enrolled patients, there were 54 males and 54 females with a mean age of 21.6 years (standard deviation [SD] = 7.3 years; range: 2.5-38 years). The mean Ref Hb and Sp Hb were 9.4 g/dL (SD = 0.9 g/dL; range: 7.5-12.3 g/dL) and 11.1 g/dL (SD = 1.2 g/dL; range: 7.5-14.7 g/dL), respectively. The coefficient of determination (R(2)) was 21% with a mean difference of 1.7 g/dL (SD = 1.1 g/dL; range: -0.9-4.3 g/dL). In the multivariable model, the Ref Hb level (P = 0.001) was the only statistically significant predictor. CONCLUSION: The Pronto-7(®) pulse CO-oximetry device was found to overestimate Hb levels in patients with TM and therefore cannot be recommended. Further larger studies are needed to confirm these results.