A not-so-basic case of metabolic alkalosis: an analysis featuring Leendert Paul and emphasizing Occam’s razor

A patient had the onset of a severe degree of metabolic alkalosis associated with a very large daily loss of diarrheal fluid. Because the expected acid-base disorder in this setting is metabolic acidosis, factors that could result in the markedly increased concentration of bicarbonate (HCO₃⁻) in plasma (P ₃) were sought. In our approach, there is an emphasis on electroneutrality, mass balance, a quantitative analysis, and the application of basic concepts in physiology at the bedside. We suggest that there were 3 major factors that could explain why the P ₃ was so high. First, a severe degree of extracellular fluid volume contraction was probably the most important factor that raised her P ₃. Second, there may have been an unusual way to have an electroneutral addition of HCO₃⁻ and removal of chloride ions from her extracellular fluid compartment. Third, the diarrheal fluid could have contained little HCO₃⁻ because of a down-regulated intestinal secretion of HCO₃⁻. This analysis challenges the traditional pathophysiology of metabolic alkalosis.     

A DPSIR Approach to Selected Cr(VI) Impacted Groundwater Bodies of Central Greece

Bulletin of Environmental Contamination and Toxicology - The holistic approach of Driver-Pressure-State-Impact-Response (DPSIR) methodology was applied to selected Cr(VI) impacted groundwater...     

Chemical Renal Denervation by Vincristine: The Role of the Flow Rate of Delivery

Purpose

Vincristine has been proven promising regarding its safety and efficacy for the renal artery denervation both in experimental models and in humans. The aim of the study was to compare in an experimental model the efficacy of constant versus random flow rate delivery of vincristine on renal sympathetic denervation.

Methods

We used 10 juvenile Landrace swine. After the introduction of a 7F sheath into the femoral artery, a guide wire was advanced into the distal part of the renal artery. Then the first delivery balloon catheter, which delivers vincristine in random flow rate, was advanced at the proximal part of the artery, and the balloon was inflated in order to locally deliver vincristine to the media of the renal artery. The process was repeated in the contralateral renal artery, with the use of the double balloon catheter that delivers vincristine with a constant flow rate. Euthanasia of the animals was performed at 28 days. All sections were processed for histological and immunohistochemical analysis.

Results

The delivery of vincristine with both catheters was successful and uncomplicated. Immunohistochemistry showed that the mean number of intact nerves in all sections was significantly lower in the group of vincristine delivered with constant flow catheter compared to the group that the delivery was performed in a random fashion. (1.48 ± 0.37 vs. 1.70 ± 0.41, p = 0.04).

Conclusion

Chemical renal denervation with vincristine by a constant flow rate catheter is more effective compared to the denervation performed by a catheter that delivers vincristine in a random fashion.     

A multicenter evaluation of the appropriate use of single-photon emission tomography myocardial perfusion imaging in Greece

Background

This study evaluates the appropriate use of myocardial perfusion imaging (MPI) and determines patterns and variables associated with inappropriate testing.

Methods

Over a 10-month period data were collected prospectively from consecutive patients referred for MPI in four academic departments and an appropriate use grade was assigned (appropriate, uncertain, inappropriate, and unclassifiable scans) according to established criteria.

Results

Among 3,032 referrals appropriate MPI had 72.8% of patients and 19.2% of studies were inappropriate, the remaining being uncertain (7.2%) or unclassifiable (0.8%). In multivariate analysis the asymptomatic status (odds ratio 10.7, P < .001), good functional capacity (odds ratio 1.9, P < .001), an interpretable resting electrocardiogram (odds ratio 1.8, P = .004), an age <65 years (odds ratio 1.5, P = .001) and the absence of diabetes (odds ratio 1.7, P < .001) or dyslipidemia (odds ratio 1.3, P = .014) were independent predictors of inappropriate scintigraphy. The most common indication for inappropriate testing was the assessment of asymptomatic patients <2 years after percutaneous coronary intervention (PCI) (38.9%).

Conclusions

The appropriate use of MPI is relatively high, but a considerable proportion of inappropriate scans is noted which is associated with markers of lower risk. The most common source of inappropriate testing is the assessment of asymptomatic patients <2 years after PCI.     

Antegrade versus retrograde cerebral perfusion in relation to postoperative complications following aortic arch surgery for acute aortic dissection type A

Abstract   Background: Aortic arch surgery is impossible without the temporary interruption of brain perfusion and therefore is associated with high incidence of neurologic injury. The deep hypothermic circulatory arrest (HCA), in combination with antegrade or retrograde cerebral perfusion (RCP), is a well-established method of brain protection in aortic arch surgery. In this retrospective study, we compare the two methods of brain perfusion. Materials and Methods: From 1998 to 2006, 48 consecutive patients were urgently operated for acute type A aortic dissection and underwent arch replacement under deep hypothermic circulatory arrest (DHCA). All distal anastomoses were performed with open aorta, and the arch was replaced totally in 15 cases and partially in the remaining 33 cases. Our patient cohort is divided into those protected with antegrade cerebral perfusion (ACP) (group A, n = 23) and those protected with RCP (group B, n = 25). Results: No significant difference was found between groups A and B with respect to cardiopulmonary bypass-time, brain-ischemia time, cerebral-perfusion time, permanent neurologic dysfunction, and mortality. The incidence of temporary neurologic dysfunction was 16.0% for group A and 43.50% for group B (p = 0.04). The mean extubation time was 3.39 ± 1.40 days for group A and 4.96 ± 1.83 days for group B (p = 0.0018). The mean ICU-stay was 4.4 ± 2.3 days for group A and 6.9 ± 2.84 days for group B (p = 0.0017). The hospital-stay was 14.38 ± 4.06 days for group A and 19.65 ± 6.91 days for group B (p = 0.0026). Conclusion: The antegrade perfusion seems to be related with significantly lower incidence of temporary neurological complications, earlier extubation, shorter ICU-stay, and hospitalization, and hence lower total cost.     

Writing a research abstract: eloquence in miniature

Abstracts are summaries, usually of a full article or conference presentation, and may be classified into structured and unstructured ones. The former have a predefined layout necessitating the use of headings. Most journals and conferences now use the structured abstract format. Research abstracts are increasingly vital for scientific communication and are expected to continue playing a key role for the dissemination of medicine in the near future. Abstracts take time and need meticulous preparation. They must aptly summarise the content of the study or presentation and avoid vague statements and poor style. Moreover, they must comply with provided instructions. Finally, they should be pleasant to read and encourage study of the corresponding full work.