Predicting Acute Renal Failure after Cardiac Surgery: Validation and Re‐definition of a Risk‐Stratification Algorithm

Background:  Acute renal failure (ARF) after cardiac surgery is associated with significant morbidity and mortality, irrespective of the need for dialysis. Previous studies have attempted to identify predictors of ARF and develop risk stratification algorithms. This study aims to validate the algorithm in an independent cohort of patients that includes a significant proportion of female and black patients and compares two different definitions of renal outcome.
Methods:  A large single center cardiac surgery database was examined (n, 24,660; 1993–2000) which included 29.9% females and 3.7% black patients. Post‐operative ARF was defined as: a) ARF requiring dialysis, b) > 50% reduction in creatinine clearance relative to baseline or requiring dialysis. Clinical variables related to baseline renal function and cardiovascular disease were used in recursive partitioning analysis for both outcome definitions. Chi‐square goodness of fit analysis was performed to validate the algorithm.
Results:  The frequency of post‐operative ARF requiring dialysis ranged between 0.5 and 15.5% based on the risk categories with the area under the receiver operating characteristic (ROC) curve of 0.78. Using the more inclusive definition of ARF, the frequency was significantly higher ranging from 2.6 to 25%(P < 0.001) with an area under ROC curve of 0.65.
Conclusions:  The renal risk stratification algorithm is valid in predicting post‐operative ARF in an independent cohort of patients, well represented by differences in gender and race. Since the need for dialysis remains subjective, a more objective and inclusive definition of ARF may help in identifying a larger number of patients 'at‐risk'.     

A new T-tube applier in laparoscopic surgery

The level of blood lipids and apolipoproteins in subjects being screened for abdominal aortic aneurysms have been investigated. As part of an ultrasound screening programme in a population of 65- to 75-year-olds, blood samples were collected from 1460 of 1504 subjects with a normal aorta (97.1%) and 69 of 70 patients with an abdominal aortic aneurysm > 29 mm (99%). Samples were also taken from 22 of 27 patients (81%) with an ectatic aorta (26-29 mm). Total cholesterol, HDL-cholesterol, LDL-cholesterol, Apo-AI and Apo-B levels were significantly higher in women than in men (P < 0.01). Levels of HDL-cholesterol and Apo-AI were significantly lower in patients with an abdominal aortic aneurysm than in normal subjects (P < 0.001). The mean(s.d.) body mass index was 25.1(3.9) in women and 25.5(3.2) in men with aneurysms and not significantly greater than that of normal subjects (25.2(3.61) and 25.2(3.38) respectively).     

Impact of polarization and incidence of the ASAR sensor on coastline mapping: example of Gabon

Coastline mapping is of great interest in many different applications. In this Letter, we analyse the effect of the polarization and the incidence angle of the new Advanced Synthetic Aperture Radar (ASAR) sensor on coastline detection. Results indicate a marked dependence of the incidence angle and polarization on the delimitation between land and sea. At low incidence angles (<30°), delimitation is much clearer with HV polarization than with HH and VV polarizations. Delimitation is high whatever the polarization at high incidence angles (>30°). The multi‐polarization aspect of ASAR, in addition to its multi‐incidence aspect, therefore, allows coastline evolution to be monitored both more efficiently and more frequently. Consequently, the ASAR sensor is better adapted to coastline monitoring than the older ERS‐1/2 and Radarsat‐1 sensors.     

Near-infrared spectroscopy investigation on the hydration degree of a cement paste

Near-infrared spectroscopy is a fast and easy-to-perform technique characterized by high sensitivity regarding water containing systems and for this reason it is a suitable tool for investigating structural modifications of hydrating cementing materials, even if the lack of knowledge in this field makes the interpretation of NIR vibrational bands very difficult. In this paper, the NIR spectrum of a hydrated ordinary Portland cement is extensively investigated and an interpretation of the different bands is proposed on the basis of both experimental evidence and reference to literature. The obtained results were applied to the investigation of cement hydration lasting up to 28 days, analyzing the variations detectable in the shape of the spectrum as the reaction went on. The degree of this variation, quantified through area calculations of the main significant bands, revealed a broad agreement with the degree of hydration of the paste measured by thermal methods. The findings of this research supply a solid foundation for future in-field application of NIR spectroscopy, for example, for investigations on cements with different hydration behavior, or to evaluate the effect of additives on cement pastes and, at a further level, for cement quality control.     

A randomized, controlled, clinical study of laparoscopic vs open tension-free inguinal hernia repair

BACKGROUND: The aim of this prospective, randomized, controlled clinical study was to compare laparoscopic transabdominal preperitoneal (TAPP) hernia repair with a standard tension-free open mesh repair (open). METHODS: A total of 108 low-risk patients with unilateral (primary or recurrent) or bilateral hernias were randomized to TAPP (group 1 = 52 cases) or open (group 2 = 56 cases). The outcome measures included operating time, complications, postoperative pain, return to normal activity, operating theater costs, and recurrences. RESULTS: The mean operative time was longer for the TAPP than for the open group only in unilateral primary hernias. At rest, the median Visual Analog Scale (VAS) score was higher for group 1 than group 2 at 48 h postoperatively. Mild to discomforting pain in the inguinal region after 7 days, night pain after 30 days, and inguinal hardening after 3 months were more frequent in group 2 than group 1. No significant differences were observed in return to normal activities between the groups. One hernia recurrence was observed after 1 month in group 1. TAPP was significantly more expensive than open. CONCLUSIONS: TAPP was associated with less postoperative pain than open. The increase in operating theater costs, however, was dramatic and was not compensated by shorter time away from work. TAPP should not be adopted routinely unless its costs can be drastically reduced.     

Laparoscopic treatment of gallbladder and common bile duct stones: a prospective study

The aim of this study was to investigate prospectively the feasibility, success rate, safety, and short-term results of single-stage laparoscopic treatment of gallstones and ductal stones in 100 consecutive, unselected patients. Common bile duct (CBD) stones were diagnoses at routine intraoperative cholangiography and choledochoscopy in 100 of 950 patients with gallstones undergoing laparoscopic cholecystectomy (LC). Unsuspected CBD stones were present in 39 patients (4.1% of 950; 39% of 100); 26 patients were referred for surgery after failed endoscopic sphinctertomy (ES) performed elsewhere. Transcystic duct CBD exploration (TC-CBDE) was the procedure of choice. When it was not feasible, choledochotomy and direct CBD exploration (D-CBDE) was performed. Use of biliary drainage was liberal. A completion cholangiogram was obtained for all patients. Laparoscopic treatment of CBD stones was successful in 96 patients: after TC-CBDE in 63 and after D-CBDE in 33. Four operations were converted to open surgery (4%). Retained stones, observed in five patients, were treated by ES in two cases and by percutaneous endoscopic/fluoroscopic lithotripsy in three. Minor morbidity included biloma (n = 2), port site infection (n = 2), and subumbilical hematoma (n = 1). Major morbidity was bile leakage from the cystic duct stump in two cases due to clips or transcystic duct drainage displacement, respectively. One elderly, high risk patient died after being referred for several failed attempts of endoscopic clearance; she died from cardiogenic shock 3 days after successful laparoscopic treatment. Laparoscopic CBD exploration is feasible and safe in most patients, with short-term results that compare favorably with the results of sequential ES/LC reported in the literature.     

Predictors of mortality and the provision of dialysis in patients with acute tubular necrosis. The Auriculin Anaritide Acute Renal Failure Study Group

BACKGROUND: Improvement of angina pectoris symptoms after cholesterol lowering has raised questions as to the underlying mechanisms. METHODS: Rabbit experiment: We compared arterial blood samples from New Zealand White cholesterol-supplemented rabbits (n = 6) with nonsupplemented rabbit samples (n = 4) in a closed-loop circulation diffusion system. The pH and partial pressures of oxygen (pO2) and carbon dioxide (pCO2) were measured continuously. The samples were first oxygen (O2) saturated (pO2, 160 mm Hg; pCO2, 4 mm Hg) and then desaturated in 100% nitrogen. Cholesterol levels were determined in whole blood, plasma (P Chol), red blood cells (RBCs), and RBC membranes. Human experiment: We exposed quadruple desaturated venous blood samples (n = 4) with P Chol levels of 87 to 400 mg/dL in a gas exchanger to capillary gas conditions (pO2, 23 mm Hg; pCO2, 46 mm Hg). After 15 minutes we performed blood gas analyses and compared our results to baseline values. RESULTS: In the rabbit experiment the cholesterol-supplemented group as compared to the control group showed higher plasma pO2 levels during the saturation phase and lower plasma pO2 levels during the desaturation phase. It also had a markedly increased RBC membrane cholesterol content: 121 +/- 3 (standard error of the mean [SEM]) mg/dL versus 22 +/- 1.7 mg/dL in the control group (P < .05). This barrier to RBC membrane O2 diffusion caused delayed O2 entry into the RBCs during saturation, with a higher plasma pO2, and delayed O2 release from the RBCs during desaturation, with a lower plasma pO2. In the human experiment the P Chol level was inversely correlated with the percentage change of O2 content in milliliters of O2 per deciliter of blood (P < .05). CONCLUSIONS: Increased RBC membrane cholesterol in hypercholesterolemia appears to decrease the transmembrane O2 diffusion rate.     

Efficacy of recombinant alpha-interferon 2a and 13-cis-retinoic acid in the treatment of squamous cell carcinoma

BACKGROUND: Recent in vitro and in vivo studies hypothesize a synergistic effect of 13-cis-Retinoic Acid (13cRA) and recombinant alpha-IFN 2a (alpha-IFN) in the treatment of squamous cell carcinoma (SqCC). PATIENTS AND METHODS: 35 patients with SqCC in several sites were treated with 13cRA (0.6-1 mg/kg/day) combined with alpha-IFN (6 x 10(6) I.U./day), continuously for 3 months. RESULTS: We observed an objective response in 41% of cases (13/32 evaluable patients) with 5 complete and 8 partial responses. Toxicity was mild and always rapidly reversible, with no haematological side effects. CONCLUSIONS: These preliminary data confirm the feasibility and effectiveness of the combination of 13cRA and alpha-IFN in the therapy of SqCC, also in pre-treated patients, with acceptable toxicity and good compliance.     

Interferometric system for precise submicrometer particle sizing

Following a recently exploited line of thought, we present an interferometric system for particle sizing in the submicrometer region. The phase of the field that results from the interference between the incident and the scattered waves is measured through a heterodyne detection scheme in a Mach-Zehnder-type interferometer. We explored the possibility of extending previous work on this subject to the case of larger particles, i.e., particles larger than 0.5 mum. Experimental results obtained with polystyrene spheres in the range of diameters 0.16-0.71 mum are reported and compared with theoretical predictions. We show that in this range univocal detection of the particle size is not successful because the phase versus particle-size plot exhibits a maximum in correspondence to diameters close to 0.5 mum.