Mykola V. Tsapenko

Limiting ventilator-induced lung injury through individual electronic medical record surveillance

Background:To improve the safety of ventilator care and decrease the risk of ventilator-induced lung injury, we designed and tested an electronic algorithm that incorporates patient characteristics and ventilator settings, allowing near-real-time notification of bedside providers about potentially injurious ventilator settings. Methods:Electronic medical records of consecutive patients who received invasive ventilation were screened in three Mayo Clinic Rochester intensive care units. The computer system alerted bedside providers via the text paging notification about potentially injurious ventilator settings. Alert criteria included a Pao2/Fio2 ratio of <300 mm Hg, free text search for the words “edema” or “bilateral + infiltrates” on the chest radiograph report, a tidal volume of >8 mL/kg predicted body weight (based on patient gender and height), a plateau pressure of >30 cm H2O, and a peak airway pressure of >35 cm H2O. Respiratory therapists answered a brief online satisfaction survey. Ventilator-induced lung injury risk was compared before and after the introduction of ventilator-induced lung injury alert. Findings:The prevalence of acute lung injury was 42% (n = 490) among 1,159 patients receiving >24 hrs of invasive ventilation. The system sent 111 alerts for 80 patients, with a positive predictive value of 59%. The exposure to potentially injurious ventilation decreased after the intervention from 40.6 ± 74.6 hrs to 26.9 ± 77.3 hrs (p = .004). Interpretations:Electronic medical record surveillance of mechanically ventilated patients accurately detects potentially injurious ventilator settings and is able to influence bedside practice at moderate costs. Its implementation is associated with decreased patient exposure to potentially injurious mechanical ventilation settings.

Arterial pulmonary hypertension in noncardiac intensive care unit

Pulmonary artery pressure elevation complicates the course of many complex disorders treated in a noncardiac intensive care unit. Acute pulmonary hypertension, however, remains underdiagnosed and its treatment frequently begins only after serious complications have developed. Significant pathophysiologic differences between acute and chronic pulmonary hypertension make current classification and treatment recommendations for chronic pulmonary hypertension barely applicable to acute pulmonary hypertension. In order to clarify the terminology of acute pulmonary hypertension and distinguish it from chronic pulmonary hypertension, we provide a classification of acute pulmonary hypertension according to underlying pathophysiologic mechanisms, clinical features, natural history, and response to treatment. Based on available data, therapy of acute arterial pulmonary hypertension should generally be aimed at acutely relieving right ventricular (RV) pressure overload and preventing RV dysfunction. Cases of severe acute pulmonary hypertension complicated by RV failure and systemic arterial hypotension are real clinical challenges requiring tight hemodynamic monitoring and aggressive treatment including combinations of pulmonary vasodilators, inotropic agents and systemic arterial vasoconstrictors. The choice of vasopressor and inotropes in patients with acute pulmonary hypertension should take into consideration their effects on vascular resistance and cardiac output when used alone or in combinations with other agents, and must be individualized based on patient response.

Increased production of superoxide anion contributes to dysfunction of the arteriovenous fistula

Vascular access dysfunction causes morbidity in hemodialysis patients. This study examined the generation and pathobiological significance of superoxide anion in a rat femoral arteriovenous fistula (AVF). One week after AVF creation, there was increased production of superoxide anion accompanied by decreased total superoxide dismutase (SOD) and Cu/Zn SOD activities and induction of the redox-sensitive gene heme oxygenase-1. Immunohistochemical studies of nitrotyrosine formation demonstrated that peroxynitrite, a product of superoxide anion and nitric oxide, was present in increased amounts in endothelial and smooth muscle cells in the AVF. Because uncoupled NOS isoforms generate superoxide anion, and NOS coupling requires tetrahydrobiopterin (BH(4)) as a cofactor, we assessed NOS uncoupling by determining the ratio of BH(4) to dihydrobiopterin (BH(2)); the BH(4)-to-BH(2) ratio was markedly attenuated in the AVF. Because Src is a vasculopathic signaling species upstream and downstream of superoxide anion, such expression was evaluated; expression of Src and phosphorylated Src was both markedly increased in the AVF. Expression of NADPH oxidase (NOX) 1, NOX2, NOX4, cyclooxygenase (COX) 1, COX2, p47(phox), and p67(phox) was all unchanged, as assessed by Western analyses, thereby suggesting that these proteins may not be involved in increased production of superoxide anion. Finally, administration of tempol, a superoxide anion scavenger, decreased neointima formation in the juxta-anastomotic venous segment and improved AVF blood flow. We conclude that the AVF exhibits increased superoxide anion generation that may reflect the combined effects of decreased scavenging by SOD and increased generation by uncoupled NOS, and that enhanced superoxide anion production promotes juxta-anastomotic stenosis and impairs AVF function.

Measurement of urinary TGF-β1 in patients with diabetes mellitus and normal controls

OBJECTIVE Increasing evidence links TGF-β1 to progression of renal fibrosis including its association with diabetic nephropathy (DN). Current ELISA assays are not sensitive enough to measure TGF-β1 in the urine of many clinically healthy individuals, even those with established renal disease. The objective of this study was to validate a sensitive urinary assay for TGF-β1 and compare levels between healthy controls and patients with established DN. DESIGN AND METHODS An ELISA method (R&D Systems) was utilized together with an amplification step to assay TGF-β1 in urine samples from 190 patients with DN and 80 healthy controls. RESULTS Using an ELAST (Perkin Elmer, Inc) amplification step, the ELISA for urinary TGF-β1 had a limit of quantification of 15.6 pg/mL and limit of detection of 7 pg/mL. Preliminary studies demonstrated that TGF-β1 was stable if urine was frozen promptly at -70°C without preservatives. Using this assay, 22/80 controls (27%) had detectable levels of urinary TGF-β1 (range <7 to 40.9 pg/mL; mean±SD 6.4±11.1 pg/mL). This was significantly lower (p<0.0001) than in the DN group in whom 114/190 (60%) had detectable levels of urinary TGF-β1 (range <7 to 526.4 pg/mL; mean±SD 20.4±45.8 pg/mL). Urinary protein and TGF-β1 concentrations demonstrated modest correlation in patients with DN (r=0.47, P<0.001). TGF-β1 measurement in patients with DN did not demonstrate significant association with progression of proteinuria or increase in serum creatinine during the next 12 months of follow-up. CONCLUSION We have validated a sensitive ELISA assay for urinary TGF-β1, and demonstrated correlations with the degree of proteinuria and higher levels in patients with DN compared to controls. Additional study will be necessary in order to determine if serial testing can predict renal prognosis independent of known prognostic factors for patients with DN.

Renal histological lesions and outcome in liver transplant recipients

Tsapenko M, El‐Zoghby ZM, Sethi S. Renal histological lesions and outcome in liver transplant recipients. 
Clin Transplant 2012: 26: E48–E54. 
© 2011 John Wiley & Sons A/S.

Periodic fever syndrome with relapsing glomerulonephritis: a case report and teaching points

We report a case of relapsing mesangial and endocapillary proliferative glomerulonephritis (GN) associated with a periodic fever syndrome. The patient presented 11 times in >4 years with acute febrile episode followed in 1–3 days by hematuria, thrombocytopenia and other symptoms of acute GN with variable severity of acute kidney injury. In three episodes, the patient required renal replacement therapy for 7, 10 and 2 treatments, respectively. Shortly after the acute symptoms of the febrile episode had resolved each time, the kidney function would recover and the serum creatinine would return to baseline. Two kidney biopsies obtained during separate episodes showed acute tubular injury along with morphological changes resembling post-infectious GN but with no clinical evidence to support an infectious etiology. Multiple treatment regimens were unable to control the disease. Symptoms were alleviated by rituximab but did not completely remit. Stable remission of the periodic fever and GN was finally achieved after anakinra therapy was initiated 18 months ago. Since then, the patient had several episodes of documented infection without high fever and nephritic kidney manifestations. His kidney function remained stable with normal serum creatinine.