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Biomedical subjects

R G Cohen

Publications and source records attributed to R G Cohen.

32 records · Page 2Linked to original sources
PubMed1994

Living-related donor lobectomy for bilateral lobar transplantation in patients with cystic fibrosis.

Donor lobectomy has been performed in 14 patients enabling 7 recipients with cystic fibrosis to undergo bilateral living-related lobar pulmonary transplantation. Donors included 11 patients, 2 brothers, and 1 uncle. Donor mean age was 43 years (range 24 to 55 years). Their mean height and weight was 170 cm (range, 169 to 180 cm) and 72.4 kg (range, 55 to 90 kg), respectively, compared with 161 cm (range, 140 to 175 cm) and 42.4 kg (range, 27 to 55 kg), respectively, in the recipient group. Donor pulmonary evaluation consisted of a history and physical examination, chest roentgenogram and computed tomographic scan, spirometry with arterial blood gas measurement, echocardiography, and perfusion scanning. From each pair of donors, one was selected for right lower lobectomy and the other for left lower lobectomy. Standard lobectomy techniques were modified to facilitate implantation and optimize preservation of the donor lobes. On the right side, the middle lobe was removed and discarded in the first three donors to provide an adequate cuff of pulmonary artery and bronchus for implantation. With increased experience, this has proved not to be necessary. There have been no deaths and no long-term complications in the donor group. Prolonged postoperative air leaks occurred in the 3 patients who underwent right lower and middle lobectomies. All donors have been able to resume their previous lifestyles. Living-related donor lobectomy provides an alternative to cadaveric organs in select patients in need of pulmonary transplantation.

Adolescent↗
PubMed1994

Lobar transplantation. Indications, technique, and outcome.

Lobar transplantation represents a therapeutic option for children and some adults with severe end-stage pulmonary disease. Six patients including two neonates, three children, and one adult underwent lobar transplantation. Ages ranged from 17 days to 21 years. Transplant procedures were unilateral in the neonates and two of the children and bilateral in the child and adult who had cystic fibrosis. The donor lobes were from cadavers in the two neonates and living related donors in the children and the adult. Unilateral grafts involved use of the right upper lobe in the 12-year-old patient with bronchopulmonary dysplasia; right middle lobe with a ventricular septal defect repair in the 4-year-old patient with Eisenmenger's syndrome, left upper lobe in the 28-day-old patient with primary pulmonary hypertension, and the right upper and middle lobes in the 17-day-old patient with diaphragmatic hernia. Bilateral lobar transplantations were performed with the right lower and left lower lobes in the two patients with cystic fibrosis (aged 13 and 21 years). The two neonates underwent emergency transplantation with the use of extracorporeal membrane oxygenation as a bridge. Perioperative survival was 83%, with only the 4-year-old patient with ventricular septal defect/Eisenmenger's syndrome dying early. No airway complications were observed. The unilateral grafts received most of the blood flow as shown by perfusion scanning (range 74% to 99%). Living related donor complications included prolonged air leaks (> 6 days) in two patients. In urgent situations, such as an infant requiring extracorporeal membrane oxygenation, and in the existing milieu of donor shortage, lobar transplantation (living related or cadaveric) is a surgically feasible procedure and can provide a donor source in the limited time frame of these clinical situations. Bilateral lobe transplantation may be a viable option for patients with cystic fibrosis and life-threatening respiratory decompensation.

Adolescent↗
PubMed1993

Pediatric lung transplantation.

As the first decade of successful clinical lung transplantation draws to a close, the number of patients who are able to benefit from it continues to increase. Pulmonary transplantation in the pediatric age group is possible for an expanding range of diagnoses currently known to cause end-stage lung disease. However, more experience will be required before the answers to a number of clinical problems are found. The following issues are particularly pertinent to the pediatric age group: (1) Controversy still exists as to the most appropriate operation for certain clinical situations (eg, single- or double-lung transplants for primary pulmonary hypertension, or secondary pulmonary hypertension after cardiac repair). These decisions are made based on physiological considerations as well as donor availability and the need to use the donor pool as efficiently as possible. (2) Technical controversies in pediatric lung transplantation include the optimal technique for performing the bronchial anastomosis in a manner that will permit healing without stenosis of the airway. Cardiopulmonary bypass is required for most lung transplants in children. (3) OB continues to plague the long-term results of lung transplantation and may be more common in the pediatric age group. OB may respond to increased immunosuppression. (4) Lobar transplantation in children may be an effective method of increasing the availability of donors. More experience will be necessary to further refine this technique.

Adolescent↗
PubMed1986

A 7 year experience with low anterior sigmoid resections using the EEA stapler.

The EEA stapler was used in 205 patients over a 7 year period with 19 complications (9 percent) and 1 death (0.5 percent). Meticulous attention to technique and familiarization with the EEA stapler are necessary to achieve such results. The use of mechanical and oral antibiotic bowel preparation, perioperative systemic antibiotics, povidone-iodine irrigation of the rectal ampulla, and meticulous surgical technique have combined to lower the complication rate of this procedure to a minimum. The EEA stapler has greatly improved the safety and ease of anterior sigmoid resections and now provides a frequent alternative to abdominoperineal resection in many patients with midrectal and even low rectal lesions.

Adenocarcinoma↗
PubMed1986

Autologous pericardium versus a xenograft substitute in myocardial wound healing.

This study compared repair of myocardial wounds covered with autologous pericardium to healing of wounds covered with glutaraldehyde-preserved bovine pericardium in an experimental canine model. Right (RV) and left (LV) full thickness ventriculotomies were made and closed. In the control group (n = 12), the pericardium was closed over the wound; in the experimental group (n = 12), wounds were covered with bovine pericardium. Animals were sacrificed at 14, 21, 28, and 42 days. After excising the pericardium, 6 mm punch biopsies of normal RV, RV wound, normal LV, and LV wound were assayed for hydroxyproline (HPro). Both autologous and bovine pericardium became densely adherent to the wounds. Bovine pericardium was mildly adherent over unwounded areas, while autologous pericardium was usually free. Normal RV contained more than twice as much HPro as normal LV (5.4 +/- 0.57 micrograms/mg vs 1.7 +/- 0.35 micrograms/mg, P less than 0.0002). A gradual rise in HPro over time was seen in both groups, but this increase was statistically significant only at 42 days (P less than 0.05). There was no significant difference in HPro between wounds covered with autologous pericardium and those covered with bovine grafts (P = 0.13) at any of the sample times in this study. In this experimental canine model, the pericardium does not appear to play a prominent role in myocardial wound healing by contributing collagen-producing fibroblasts. Furthermore, the bovine pericardial xenograft becomes densely adherent to LV and RV incisions. In the clinical setting, such may make reoperation more hazardous when the heart has been previously incised or coronary bypass grafts have been constructed.

Animals↗
PubMed1986

Biochemical (functional) adaptation of "arterialized" vein grafts.

Canine venous autografts and allografts were interposed in the femoral and carotid arterial positions in 29 dogs; grafts were harvested at three postoperative intervals (1-2 weeks, 4-6 weeks, and 8-10 weeks) for light and scanning electron (SEM) microscopy and lumenal surface prostacyclin (PGI2) production. Normal veins and arteries were used as controls. Radioimmunoassay for tritiated 6-k-PGF1 alpha, the stable metabolite of PGI2, was performed using a flow surface template incubation chamber during basal and arachidonic acid stimulated conditions. Using SEM, the autografts revealed normal endothelial cell (EC) surfaces at all time intervals; conversely, allografts exhibited extensive EC loss at 1-2 weeks with gradual reparation by 10-12 weeks (such that the EC surface was virtually indistinguishable from that of control veins or autografts). PGI2 production was significantly greater in control arteries than veins (p = 0.0001). At 1-2 weeks and 4-6 weeks, lumenal production of PGI2 in both the autografts and allografts was not significantly different from control vein; however, PGI2 production after 10-12 weeks was identical to normal arterial levels (and significantly [p less than 0.0044] higher than venous levels) in both basal and stimulated conditions. Although the mechanisms responsible for this functional (biochemical) "arterialization" process remain conjectural, increased biosynthesis and/or release of PGI2 by endothelial cells, acute phase inflammatory cells (allografts) mediated by interleukin-1 or myointimal cells seems most likely. Further elucidation of these sources of PGI2 is necessary, but these data demonstrate for the first time that venous grafts placed in the arterial circulation undergo complete functional adaptation (in addition to the well known morphological changes).

Adaptation, Physiological↗
PubMed1981

Acute alcohol ingestion and platelet function.

A substantial number of severely injured patients are under the influence of alcohol, making it important to understand the effects of acute alcoholic intoxication on the clotting mechanism. Twenty healthy volunteers ingested commercial liquor over a four-hour period and were observed for another three hours. Peak blood alcohol levels were above 200 mg/dL in four subjects and between 100 and 200 mg/dL in 12. Platelet counts, platelet aggregation, and bleeding times were not significantly altered over the seven hours. This study demonstrates that acute alcoholic intoxication in healthy persons does not alter platelet function.

Adult↗
PubMed1981

Coagulation changes after albumin resuscitation.

The administration of albumin in the initial resuscitation of shock remains highly controversial. Impaired coagulation in the critically injured patient has recently been added as an argument against the use of supplemental albumin. This study investigated the hemostatic effects of albumin therapy after hemorrhagic shock. Twenty mongrel dogs were bled to a systolic pressure of 60 mm Hg for 1 h. After the return of shed blood, the animals received either lactated Ringer's solution or 5% serum albumin (25 ml/kg) daily for the 3 days. Coagulation parameters were measured before bleeding, immediately after resuscitation, and on days 2, 3, and 4. The changes in platelet count, platelet function, and serum fibrinogen were similar in the albumin treated and control animals. Although the prothrombin time and partial thromboplastin time were more prolonged in the albumin group, the changes were not sufficient to produce clinical bleeding.

Animals↗