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Biomedical subjects

A S Pathak

Publications and source records attributed to A S Pathak.

7 recordsLinked to original sources
PubMed2005

One-step percutaneous nephrolithotomy sheath versus standard two-step technique.

OBJECTIVES: Advances in technique and equipment have allowed urologists to perform percutaneous stone removal with increasing efficacy and decreasing complications. The procedure of choice for large renal calculi is percutaneous nephrolithotomy. At our institution, percutaneous access is achieved by a two-step process using either Amplatz dilators or placement of a high-pressure balloon catheter for tract dilation, followed by advancement of a sheath over the balloon. A novel device, the Pathway Access Sheath (PAS) has been developed that allows for balloon tract dilation and percutaneous access sheath placement in one simple step. METHODS: Our study population consisted of 21 patients, who were randomized to one of two arms. Of the 21 patients, 10 underwent standard two-step access using a high-pressure balloon catheter and 11 underwent percutaneous nephrolithotomy using the novel PAS. We compared the insertion time, blood loss, and cost between the two techniques. RESULTS: The average insertion time was shorter in the PAS group (3 minutes) compared with the high-pressure balloon catheter (5 minutes, 42 seconds); a difference that was statistically significant (P <0.01). The estimated blood loss and cost were similar between the two groups. The increased sheath flexibility of the PAS was noted to be an advantage in some patients. CONCLUSIONS: The results of our study have shown that a novel single-step renal access device is safe and efficacious and results in a shorter insertion time for percutaneous nephrolithotomy. Blood loss was less in the PAS group as well, although the difference was not statistically significant. Additional studies will establish whether this device will provide a new standard of obtaining renal access.

Adolescent↗
PubMed2001

Injuries of the inferior vena cava.

Injuries of the IVC, whether caused by blunt or penetrating mechanisms, are usually fatal. Patients who arrive in shock and fail to respond to initial resuscitative measures, those who are still actively bleeding at the time of laparotomy, and those with wounds of the retrohepatic vena cava have a low probability of survival. Death most commonly is caused by intraoperative exsanguination. Knowledge of the anatomy and exposure techniques for the five different segments of the intra-abdominal vena cava is very important to trauma surgeons. Although some wounds of the vena cava, especially those of the retrohepatic vena cava, are best left unexplored, most injuries inferior to this level can be exposed and repaired by lateral suture technique. Preservation of a lumen of at least 25% of normal is probably important in the suprarenal vena cava but is of no provable value inferior to the renal veins. No evidence supports the need to expose and repair vena caval wounds that have spontaneously stopped bleeding. Such wounds, especially in the retrohepatic area, may be managed expectantly provided that there is no strong suspicion of an associated injury to a major artery or hollow viscus.

Hemostatic Techniques↗
PubMed2001

Portal vein injuries.

Wounds of the portal vein are caused most commonly by penetrating trauma and carry a very high mortality rate. Most deaths are caused by exsanguination, occurring intraoperatively as surgeons struggle to control the hemorrhage from the portal vein and associated vascular injuries. A thorough knowledge of the anatomy of the area and of the likely patterns of wounding is important. At surgery, surgeons must be prepared to deal with multiple vessel wounding. Although most investigators have advocated lateral repair of the portal vein when it can be accomplished, portal ligation seems to be a safe alternative. Complex repairs are justified only when a contraindication to ligation exists. Postoperative care must recognize the need for extraordinary fluid replacement and the small risk for postoperative bowel infarction after repair or ligation of the portal vein.

Humans↗
PubMed1998

"Pancake kidney": a renal anomaly complicating aortic reconstruction.

Pancake kidney is a rare fusion anomaly of the kidneys characterized by the presence of a displaced, lobulated pelvic renal mass of dual parenchymatous system without intervening septum. The existence of this anomaly during aortic reconstruction presents a great technical challenge. The surgical management of a 51-year-old man with a 5.0 cm aortic aneurysm and a pancake kidney is described.

Anastomosis, Surgical↗
PubMed1996

Increased activation of the coagulation and fibrinolytic systems leads to hemorrhagic complications during left ventricular assist implantation.

BACKGROUND: Left ventricular assist devices (LVADs) have provided a new therapeutic option for patients with end-stage heart failure. Despite advances in device design, there remains an apparent bleeding diathesis, which leads to increased transfusion requirements and reoperative rates. The purpose of our study was to examine the abnormalities that might contribute to these clinical sequelae. METHODS AND RESULTS: To separate the effects of cardiopulmonary bypass (CPB), eight patients undergoing coronary revascularization (CABG) were compared with seven LVAD (TCI HeartMate) recipients intraoperatively and 2 hours postoperatively. We evaluated several well-characterized indexes of platelet activation: platelet count, platelet factor 4 (PF4), beta-thromboglobulin (beta-TG), and thromboxane B2 (TXB2). We also measured activation of thrombin: thrombin-antithrombin III (TAT), prothrombin fragment 1 + 2 (F1 + 2), and fibrinopeptide A (FPA) as well as markers of fibrinolysis: plasmin-alpha 2-antiplasmin (PAP) and D-dimer. Patterns of intraoperative platelet adhesion and activation were not statistically different in the CABG control and LVAD groups. In the immediate postoperative period, however, there was significant release of PF4 and beta-TG and generation of TXB2. Compared with the CABG controls (TAT, 26 +/- 8 micrograms/L; F1 + 2, 4 +/- 1 nmol/L; mean +/- SEM), there was a significant increase in TAT (380 +/- 112 micrograms/L) and F1 + 2 (23 +/- 4 nmol/L) in LVAD patients 2 hours after surgery. Furthermore, a sharp rise in FPA was noted 20 minutes after LVAD initiation (CABG, 8 +/- 4 ng/mL; LVAD, 235 +/- 63 ng/mL; P < .05). A concomitant increase in both PAP (CABG, 987 +/- 129 micrograms/L; LVAD 3456 +/- 721 micrograms/L; P < .05) and D-dimer (CABG, 1678 +/- 416 ng/mL; LVAD, 15243 +/- 4682 ng/mL; P < .05) was observed. CONCLUSIONS: The additive effects of CPB and LVAD lead to platelet activation as well as elevation of markers of in vivo thrombin generation, fibrinogen cleavage, and fibrinolytic activity. The etiology of these findings may be secondary to the LVAD surface, flow characteristics, and/or operative procedure. Nevertheless, platelet alterations and exaggerated activation of the coagulation and fibrinolytic systems may contribute to the clinically observed hemostatic defect.

Adolescent↗
PubMed1993

Quantitative analysis of the Landis method.

Landis developed the single capillary micro-occlusion method for the determination of the capillary filtration coefficient, Lp. More recently, several modified versions of Landis's original procedure have been introduced in an attempt to measure Lp with greater ease and accuracy. Each of the techniques assumes that the capillary is a uniformly cylindrical indistensible tube. Since recently obtained experimental data have demonstrated that the capillary is compliant, a distributed mathematical model of the capillary was developed to reveal the extent to which capillary distensibility influences the measurement of Lp at different sites along the capillary. After assigning physiologic values to this modeled capillary, including Lp and the capillary wall's modulus of elasticity, Landis's method and two of its modified versions were performed on the modeled capillary, with each yielding values for Lp at 10 different locations along the capillary. Comparison of these 10 computed Lp values with the corresponding Lp values defined in the modeled capillary demonstrates that capillary distensibility can introduce significant error into the measurement of Lp.

Animals↗