Correction of metabolic acidosis and its effect on albumin in chronic hemodialysis patients

Serum albumin concentration has been strongly associated with risk of death in hemodialysis patients, with mortality increasing as albumin decreases. Metabolic acidosis stimulates protein catabolism and decreases protein synthesis. A study was undertaken to investigate the effect of increasing predialysis serum bicarbonate (HCO3) concentrations on the nutrition of hemodialysis patients as measured by albumin and total lymphocyte count (TLC). Metabolic acidosis was defined as a predialysis serum bicarbonate concentration of < or = 18 mEq/L. Thirty-six hemodialysis patients were enrolled in the study. Each had been stable on hemodialysis for > or = 3 months and each had a mean serum bicarbonate concentration of < or = 18 mEq/L on predialysis monthly laboratory values during the preceding 3 months. The subjects were randomized into 2 groups. The first group consisted of 18 control subjects who were dialyzed on a standard bicarbonate bath of 35 mEq/L. The second group consisted of 18 experimental patients who were dialyzed on a bicarbonate bath of 40 mEq/L. Subjects in the experimental group who had predialysis serum bicarbonate concentrations less than 22 mEq/L after 2 weeks on the higher bicarbonate bath were additionally supplemented with oral sodium bicarbonate at a dosage of 1 mEq/kg dry weight/d. Monthly predialysis laboratory values were checked for all subjects and included serum electrolytes, blood urea nitrogen, calcium, and albumin. TLCs were obtained at the initiation and at the conclusion of the study. Intact parathyroid hormone, blood pressures, and interdialytic weight gains were also followed. The study lasted 16 weeks; 32 subjects completed the study (16 in each group). There were no statistically significant differences between the two groups at the initiation of the study. The serum bicarbonate concentrations were significantly different between the two groups at the end of the study (control HCO3 17.3 +/- 3.2 mEq/L v experimental HCO3 20.2 +/- 2.9 mEq/L; P = 0.01). Serum albumin concentrations and TLCs were not statistically different (P > 0.05) between the two groups at the end of the study (control albumin 3.88 +/- 0.28 g/dL v experimental albumin 3.76 +/- 0.26 g/dL and control TLC 1,780.0 +/- 779.4/mm3 v experimental TLC 2,020.1 +/- 888.0/mm3). Potassium, intact parathyroid hormone, interdialytic weight gain, blood pressures, Kt/Vs, and protein catabolic rates did not differ. We found that the change in serum bicarbonate concentration was well-tolerated and was without any demonstrable side effects. We conclude that increasing the serum bicarbonate concentration by 3 mEq/L for 16 weeks has no effect on the indicators of nutrition that we measured (serum albumin and TLC).     

The prevalence of peripheral arterial disease and medial arterial calcification in patients with chronic renal failure: requirements for diagnostics

BACKGROUND: Knowledge of the prevalence of peripheral arterial disease (PAD) in patients with chronic renal failure (CRF) is limited because of a lack of uniformity in disease definition and recognition. Furthermore, little is known of the prevalence of medial arterial calcification (MAC) in patients with CRF. Our goal is to study the prevalence of PAD and MAC defined by ankle brachial index (ABI) or toe brachial index (TBI) measurements in a Finnish population of patients with CRF consisting of predialysis and dialysis patients, as well as renal transplant recipients. METHODS: We examined 136 patients with CRF and 59 control subjects. Fifty-nine of the patients with CRF had moderate to severe predialysis CRF, 36 patients were on dialysis treatment, and 41 were renal transplant recipients. Mean age of patients was 51.9 +/- 11.5 years, and 39 patients (29%) had diabetes. ABI and TBI were measured by means of photoplethysmography. The definition of PAD required an ABI value of 0.90 or less, a TBI value of 0.60 or less, or a previous positive lower-extremity angiogram result. ABI values of 1.3 or greater or incompressible arteries at ankle level indicated MAC. The presence of claudication was determined by an interview. RESULTS: Prevalences of PAD on this study were 22.0% in patients with predialysis CRF, 30.6% in patients on dialysis treatment, 14.6% in renal transplant recipients, and 1.7% in the control group (P = 0.001). Prevalences of MAC were 23.7%, 41.7%, 23.1%, and 3.4% (P < 0.001), respectively. Only 9 patients had claudication, and 6 of those patients had PAD. CONCLUSION: Both asymptomatic PAD and MAC are common in patients with CRF. Therefore, we recommend the use of both ABI and TBI measurements in the evaluation of PAD in patients with CRF.     

Hyperbaric oxygen therapy improves angiogenesis and bone formation in critical sized diaphyseal defects

Besides the use of autologous bone grafting several osteoconductive and osteoinductive methods have been reported to improve bone healing. However, persistent non‐union occurs in a considerable number of cases and compromised angiogenesis is suspected to impede bone regeneration. Hyperbaric oxygen therapy (HBO) improves angiogenesis. This study evaluates the effects of HBO on bone defects treated with autologous bone grafting in a bone defect model in rabbits. Twenty‐four New‐Zealand White Rabbits were subjected to a unilateral critical sized diaphyseal radius bone defect and treated with autologous cancellous bone transplantation. The study groups were exposed to an additional HBO treatment regimen. Bone regeneration was evaluated radiologically and histologically at 3 and 6 weeks, angiogenesis was assessed by immunohistochemistry at three and six weeks. The additional administration of HBO resulted in a significantly increased new bone formation and angiogenesis compared to the sole treatment with autologous bone grafting. These results were apparent after three and six weeks of treatment. The addition of HBO therapy to autologous bone grafts leads to significantly improved bone regeneration. The increase in angiogenesis observed could play a crucial role for the results observed. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:513–520, 2015.     

Adipose derived stem cells and nerve regeneration

Injuries to peripheral nerves are common and cause life-changing problems for patients alongside high social and health care costs for society. Current clinical treatment of peripheral nerve injuries predominantly relies on sacrificing a section of nerve from elsewhere in the body to provide a graft at the injury site. Much work has been done to develop a bioengineered nerve graft, precluding sacrifice of a functional nerve. Stem cells are prime candidates as accelerators of regeneration in these nerve grafts. This review examines the potential of adipose-derived stem cells to improve nerve repair assisted by bioengineered nerve grafts.     

The provision of a time-critical elective surgical service during the COVID-19 Crisis: a UK experience

IntroductionWith the emergence of the COVID-19 pandemic, all elective surgery was temporarily suspended in the UK, allowing for diversion of resource to manage the anticipated surge of critically unwell patients. Continuing to deliver time-critical surgical care is important to avoid excess morbidity and mortality from pathologies unrelated to COVID-19. We describe the implementation and short-term surgical outcomes from a system to deliver time-critical elective surgical care to patients during the COVID-19 pandemic.Materials and methodsA protocol for the prioritisation and safe delivery of time-critical surgery at a COVID-19 ‘clean’ site was implemented at the Nuffield Health Exeter Hospital, an independent sector hospital in the southwest of England. Outcomes to 30 days postoperatively were recorded, including unplanned admissions after daycase surgery, readmissions and complications, as well as the incidence of perioperative COVID-19 infection in patients and staff.ResultsA total of 128 surgical procedures were performed during a 31-day period by a range of specialties including breast, plastics, urology, gynaecology, vascular and cardiology. There was one unplanned admission and and two readmissions. Six complications were identified, and all were Clavien-Dindo grade 1 or 2. All 128 patients had preoperative COVID-19 swabs, one of which was positive and the patient had their surgery delayed. Ten patients were tested for COVID-19 postoperatively, with none testing positive.ConclusionThis study has demonstrated the implementation of a safe system for delivery of time-critical elective surgical care at a COVID-19 clean site. Other healthcare providers may benefit from implementation of similar methodology as hospitals plan to restart elective surgery.