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Biomedical subjects

J Saifi

Publications and source records attributed to J Saifi.

9 recordsLinked to original sources

Cardiopulmonary bypass.

There has been a recent renewed interest in certain aspects of cardiopulmonary bypass employing extracorporeal circulation. Several areas have received special attention. Among these is the institution of extracorporeal circulation using a percutaneous technique for circulatory assistance during high-risk percutaneous transluminal coronary angioplasty. A national registry has been established to review and monitor results using this percutaneous technique. Several recent developments in the delivery of cardioplegia during ischemic arrest have stimulated investigative efforts. In particular, the delivery of cardioplegia in a retrograde manner through the coronary sinus has proved an effective and useful adjunct to myocardial protection during cardiopulmonary bypass with extracorporeal circulation. A newer investigative technique employing only warm cardioplegia delivered primarily through the retrograde coronary sinus route seems to offer some promise in providing optimal myocardial protection while minimizing hemorrhagic complications and other cold-induced myocardial injury. Because of concerns regarding blood transfusion-related communicable disease (eg, acquired immune deficiency syndrome and non-A, non-B hepatitis), there has been increasing research effort into postoperative hemorrhage related to cardiopulmonary bypass with extracorporeal circulation. Specifically, various drugs that may serve as hemostatic adjuncts have been investigated extensively. These drugs include aprotinin and desmopressin acetate. Likewise, several studies have evaluated other drugs (mainly aspirin) that have a negative influence on postoperative hemostasis. Additionally, there has been continued research interest in the activation of the inflammatory system during cardiopulmonary bypass.(ABSTRACT TRUNCATED AT 250 WORDS)

Aprotinin↗

Benefits of intra-abdominal pack placement for the management of nonmechanical hemorrhage.

Massive nonmechanical bleeding following severe liver injury is a difficult problem. Placement of intra-abdominal packs tamponades this nonmechanical bleeding and allows time for correction of various metabolic disturbances (ie, hypothermia, hypotension, acidosis, and coagulopathy). The purpose of this retrospective study was to evaluate the severity of these metabolic disturbances at the time of pack placement and the sequential improvement. It was found that most life-threatening disturbances that developed during the initial operative procedure could be corrected within 18 hours after pack placement and aggressive resuscitation. We concluded that the onset of nonmechanical bleeding and a coagulopathy marks a grave prognosis for the patient, and consideration should be given at this time for pack placement. Patients can then be aggressively resuscitated and returned to the operating room within 24 hours for pack removal if stability is achieved.

Acidosis↗

The role of extraanatomic exclusion bypass in the treatment of disseminated atheroembolism syndrome.

We treated six patients with disseminated atheroembolism complicated by severe and unremitting pain from bilateral foot lesions. All patients had multiple and severe medical risk factors. One patient had a recent myocardial infarction, six patients had renal failure, and three were undergoing hemodialysis. Definitive aortic reconstruction was therefore precluded. After failing a course of medical therapy, each patient was treated with axillobifemoral bypass with exclusion-ligation of the external iliac arteries. Healing of foot wounds occurred in 11 of 12 limbs at risk, with one below-knee amputation required for progressive forefoot necrosis. In 12 patients with severe cardiopulmonary disease and limited life expectancy, exclusion-ligation bypass is an effective and safe palliative procedure for severe disseminated atheroembolism.

Aged↗

An animal model for instructing and the study of in situ arterial bypass.

A canine model that used the cephalic vein to bypass from the brachial to the ulnar artery was designed for use in instructing and evaluating surgical technique needed for constructing an in situ arterial bypass. This model was used for instructing vascular residents in the in situ vein bypass technique. The use of this model enabled the resident to become more adept with the instruments for valve incision and construction of small vessel anastomosis. The improvement in the resident's operative technique was reflected by a decrease in the number of technical complications (missed valves, missed arteriovenous fistulas, poorly constructed anastomoses) and improved patency rate.

Animals↗

Remote distal arteriovenous fistula to improve infrapopliteal bypass patency.

The results of the use of prosthetic materials for femorocrural bypass surgery have been less than optimal. The creation of a distal anastomotic arteriovenous fistula to augment blood flow and velocity through the graft is well known. However, it may create turbulence at the anastomosis and steal blood flow away from the distal artery. A canine model was developed to evaluate the effect of fistula size on graft/arterial hemodynamics. In 16 patients we have constructed a distal arteriovenous fistula, which is remote from the distal anastomosis, and we studied the effect of such fistulas on bypass patency and distal arterial hemodynamics. Patients selected for this procedure had multiple previously failed reconstructions and limb-threatening ischemia and did not have usable autogenous vein. Femorotibial bypass graft reconstructions were performed with polytetrafluoroethylene followed by the creation of a side-to-side arteriovenous fistula 5 to 15 cm below the distal anastomosis in the same artery and accompanying veins. We have achieved a 1-year patency of 67% with a 75% limb salvage rate. We also serially measured blood flow and velocity within the bypass, the arteriovenous fistula, and the distal outflow vessel using duplex scanning after surgery. Mean estimated blood flow through the bypass during the immediate postoperative period was 264 ml/min, the arteriovenous fistula was 157 ml/min, and the distal artery was 19 ml/min. Unlike an arteriovenous fistula created at the distal anastomosis, a remote distal arteriovenous fistula not only increases graft blood flow but also augments native arterial blood flow between the distal anastomosis and fistula and thus may improve distal limb perfusion.

Animals↗

Influence of hematocrit on cardiopulmonary function after acute hemorrhage.

The 'optimal' hematocrit to which patients should be resuscitated after shock and trauma is controversial. To test the hypothesis that sufficient oxygen delivery can be provided at a lower hematocrit without impairing oxygen consumption or hemodynamic function, 25 patients were prospectively studied immediately following injury and/or acute hemorrhage. Patients were randomized to have their hematocrits (HCT) maintained near 30% (29.7 +/- 0.4% (M +/- SEM); n = 12) or 40% (38.4 +/- 0.6%, n = 13). Cardiopulmonary parameters were measured twice a day for 3 days. Statistical analysis used a repeated measures analysis of variance with patient age, and ventilator parameters (FIO2, PEEP, and ventilator mode) as covariates. Arterial and venous O2 saturations were not significantly different at different hematocrits, although arterial and venous O2 contents were lower at 30% HCT (a = 14.1 +/- 0.2 m10(2)/dl, v = 10.1 +/- 0.3 m10(2)/dl; vs. a = 17.4 +/- 0.4 m10(2)/dl, v = 13.6 +/- 0.6 m10(2)/dl; p less than 0.05). This resulted in a lower oxygen delivery at the lower HCT. Between the two groups, there also was no significant difference in cardiac index (overall mean, 3.64 +/- 0.16 ml/min/m2), heart rate (99 +/- 4 bpm), systemic vascular resistance (1,058 +/- 55 dyne-sec/cm5), or left ventricular stroke work index (4.3 +/- 0.3 X 10(6) dyne-cm/m2). Intrapulmonary shunt was higher with higher hematocrit (22.6 +/- 2.4% at 40% HCT vs. 14.6 +/- 1.6% at 30% HCT; p less than 0.05) with no difference in end-expiratory pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗

In-situ breakage of an implantable venous access system.

A totally implantable system for venous access (Port-A-Cath, Pharmacia, Nu-tech) has now entered clinical use. This system consists of a silastic catheter secured to a stainless steel reservoir with a locking ring. The system has been shown to have several advantages when compared with earlier venous access systems. However, the advantages of total implantation have also disposed the system to new complications. Two cases are presented of patients who had this system placed and developed in-situ separation of the catheter from the reservoir. The catheter was removed surgically from the subcutaneous tissues in one patient and with a Dormain basket in the second because complete migration of the catheter into the central venous system had occurred. In neither patient could the precise cause for the separation be ascertained. However, it can be appreciated that if chemotherapeutic agents were infused in these patients the results would have been disastrous. It is recommended that if blood cannot be easily aspirated after gentle to and fro flushes with a 10 ml syringe, a chest radiograph be obtained prior to the infusion of any substance to check for continuity in the system. Any breaks in the system should be immediately repaired since migration of the catheter into the venous system can occur.

Adult↗

Left retroperitoneal exposure for distal mesenteric artery repair.

Distal disease in the mesenteric arteries has usually been repaired transabdominally since it is believed that only the proximal centimeter of each vessel is accessible through the retroperitoneum. We treated five patients with chronic visceral ischemia and lesions extending beyond the orifice using a retroperitoneal approach. Exposure was obtained with a left flank incision through the tenth interspace. The left crus of the diaphragm was divided in order to control the supraceliac aorta. The mesenteric vessels were identified and dissected until their entrance into the peritoneum. There were no difficulties in exposing the superior mesenteric artery (SMA) as it coursed under the pancreas and over the duodenum for an approximate length of 5 to 10 cm. The uncinate process of the pancreas was not a limiting factor for exposure of the SMA in this region and further distal exposure could be obtained by incising the peritoneum. The trifurcation of the celiac artery and the splenic artery were accessible through this exposure; however, only the first centimeter of the hepatic and gastric branches could be reached. Revascularization was performed with endarterectomy (2 patients) and bypass (3 patients). Bowel viability was assessed at the conclusion of the procedure by incising the peritoneum. There were no complications from this exposure and no patient required reoperation for ischemic bowel. We conclude that the left retroperitoneal approach is not only acceptable for orifice lesions but is also applicable for distal disease.

Blood Vessel Prosthesis↗