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Biomedical subjects

R S Shapiro

Publications and source records attributed to R S Shapiro.

At least 37 records · Page 2Linked to original sources
PubMed1997

Influence of prone position on the extent and distribution of lung injury in a high tidal volume oleic acid model of acute respiratory distress syndrome.

OBJECTIVE: To evaluate the influence of body position on the extent and distribution of experimental lung damage in an oleic acid canine model of acute respiratory distress syndrome, using mechanical ventilation with high tidal volumes and positive end-expiratory pressure (PEEP). DESIGN: Prospective, randomized study. SETTING: Experimental animal laboratory. SUBJECTS: Twelve anesthetized and paralyzed dogs. INTERVENTIONS: Ninety minutes after lung injury was induced by injection of oleic acid, 12 animals were randomized to be ventilated for 4 hrs, in either the supine (supine group, n = 6) or prone (prone group, n = 6) positions, using the same ventilatory pattern (F10(2) 0.6, PEEP > or = 10 cm H2O, and a tidal volume that generated a peak transpulmonary pressure of 35 cm H2O when implemented in the supine position). Regardless of randomization to position, the tidal volumes, F10(2), and PEEP were kept constant and the pulmonary artery occlusion pressure was maintained between 4 and 6 mm Hg for the duration of the study. MEASUREMENTS AND MAIN RESULTS: At the end of the protocol, the lungs were excised for gravimetric determination (wet/dry weight ratio) and histologic examination (histologic score). Changes over time in the static pressure-volume curve of the lungs (obtained in the supine position) were also used as end-point variables. At baseline, hemodynamic and respiratory variables did not differ between groups. Just before randomization to position (90 mins after oleic acid injection), both groups presented similar lung static pressure-volume curves. Pulmonary artery occlusion pressure (4.3 +/- 1.9 vs. 4.8 +/- 1.3 mm Hg [supine vs. prone group]), cardiac output (4.1 +/- 0.4 vs. 5.2 +/- 1.3 L/min [supine vs. prone group]), and venous admixture (36.7 +/- 20.7% vs. 28.3 +/- 19.4% [supine vs. prone group]) were also not significantly (p > .05) different when measured in the supine position. At the end of the experiment, lung gravimetric data in the two experimental groups were not statistically different, suggesting a similar extent of edema. Histologic abnormalities, however, were less in the prone group than in the supine group (p < .01), due primarily to marked differences in extent and severity in the dependent regions of the lungs. Static lung compliance improved over time in the prone group (34 +/- 9 to 46 +/- 19 mL/cm H2O)(p = .02), but not in the supine group (34 +/- 6 to 36 +/- 6 mL/cm H2O). CONCLUSIONS: After oleic acid-induced lung injury, animals ventilated with high tidal volume and PEEP undergo less extensive histologic change in the prone position than in the supine position. The prone position alters the distribution of histologic abnormalities.

Animals↗
PubMed1997

Ablative adenoidectomy: a new technique using simultaneous liquefaction/aspiration.

OBJECTIVE: This study was performed to critically evaluate a new cautery technique for adenoidectomy that combines indirect visualization with complete hemostasis, ultimately permitting the surgeon to tailor the procedure to the patient's specific needs. DESIGN: This prospective study of 138 consecutive adenoidectomy patients of the senior author was carried out at the Montreal Children's Hospital over 17 months. Concurrent adenoidectomy patients of another senior otolaryngologist in our institution as well as cases of the senior author using the conventional cold curettage technique served as controls. METHOD: Data were collected preoperatively with respect to indication for surgery and radiologic findings. Operative findings including duration of surgery, concurrent procedures, position of adenoid hypertrophy, and blood loss were also recorded. Postoperative complications such as hemorrhage, infection, dehydration, as well as the incidence of velopharyngeal insufficiency and nasopharyngeal stenosis were also recorded up to 1 year from the date of surgery. The operative technique involves indirect visualization of the nasopharynx with a laryngeal mirror combined with cautery-liquefaction and suction ablation of the adenoid tissue. RESULTS: Our results demonstrate a significant reduction in blood loss as well as a reduction in operative time. There was a low incidence of postoperative infection, no patients required a return to the operating room for hemostasis, and there were no cases of recurrent adenoid hypertrophy. There was no detectable difference in the incidence of postoperative complications. CONCLUSION: We conclude that this technique is safe and time-efficient, with the advantages of excellent visualization and essentially no operative blood loss.

Adenoidectomy↗
PubMed1996

Malignant neoplasms following bone marrow transplantation.

We undertook an analysis of 2,150 recipients of bone marrow transplant (BMT) at the University of Minnesota to determine the incidence of post-BMT malignant neoplasms (MNs). Fifty-one patients developed 53 MNs, compared with 4.3 expected from general population rates (standardized incidence ratio [SIR], 11.6, 95% confidence interval [CI], 8.2-14.5). These included 22 occurrences of B-cell lymphoproliferative disorder (BLPD), 17 solid nonhematopoietic tumors, 10 myelodysplastic syndromes (MDS), 1 acute myelogenous leukemia (AML), 2 non-Hodgkin's lymphoma (NHL), and 1 Hodgkin's disease (HD). The estimated actuarial incidence of any post-BMT malignancy was 9.9% +/- 2.3% at 13 years posttransplant. The cumulative probability of BLPD plateaued at 1.6% +/- 0.3% by 4 years from transplant and factors independently associated with increased risk included in vitro T-cell depletion of marrow (relative risk (RR) = 11.9, P < .001), HLA mismatch (RR = 8.9, P < .001), use of antithymocyte globulin (ATG) for graft versus host disease (GVHD) prophylaxis (RR = 5.9, P < .001) or in the preparative regimen (RR = 3.1, P = .03) and primary immunodeficiency (RR = 2.5, P = .06). The cumulative probability of developing solid malignancy was 5.6% +/- 2.2% at 13 years from BMT. Malignant melanomas were the most common (SIR, 10.3, 95% CI 1.9 to 25.4). The actuarial incidence of MDS/AML plateaued at 2.1% +/- 0.8% at 9 years and was seen most often in older patients receiving autologous peripheral blood stem cells for HD or NHL. These data document that BMT recipients are at an increased risk of later malignancy, which may add significant morbidity and mortality to the transplant process. Methods for screening and identification of individuals at increased risk need to be addressed in future studies.

Adolescent↗
PubMed1996

Tracheal gas insufflation: catheter effectiveness determined by expiratory flush volume.

Used adjunctively during mechanical ventilation, tracheal gas insufflation (TGI) improves CO2 elimination, principally by decreasing effective anatomic dead space. Continuing lung deflation at end- expiration raises the end-expiratory C02 concentration within the proximal airway, and could theoretically reduce the efficiency of a given catheter flow. To test this possibility, we designed a series of experiments that examined the influence of TGI delivery patterns on the efficiency of CO2 elimination. Using a gating device, catheter flow was delivered selectively during desired portions of expiration. Paralyzed, ventilated dogs were studied at short and extended inspiratory time fractions (TI/TT) with inspiratory tidal volume and ventilator frequency held constant. The expiratory flush volume, not the pattern of gas delivery, determined the observed decline in PaCO2, provided that the end-expiratory period was included in the catheter flush period. Despite continuing end-expiratory lung deflation (extended TI/TT), catheter effectiveness remained the same at matched expiratory flush volumes. To determine if enhanced distal mixing at the higher catheter flows required during the extended TI/TT (to match expiratory flush volume) masked a decrease in efficiency, we repeated the experiment with a tip-inverted catheter. We again found that matched catheter delivered expiratory volumes were similarly effective. With or without ongoing lung deflation, the volume of gas flushed during the expiratory period determined the effectiveness of TGI, provided that inspired minute ventilation remains unchanged and end-expiration is included in the catheter flush period.

Analysis of Variance↗
PubMed1996

Treatment of head and neck hemangiomas with recombinant interferon alpha 2B.

Fifteen patients with head and neck hemangiomas were treated with systemic recombinant interferon alpha 2b (rIFNalpha2b, Schering). There were 14 infants and 1 adult in the group, ranging in age from 5 weeks to 24 years old. Of the 15 patients in the group, 5 had involvement of the airway. Three of the patients had previously failed alternative systemic therapy. Twelve patients have had a beneficial response. Ten patients have completed the therapy and have been off interferon from 6 to 53 months without reappearance or progression of the disease. Two patients are currently on the therapy with resolving lesions. Three patients had minimal response and underwent successful surgical resection. No major toxicity was encountered during the therapy. Our experience demonstrates that rIFNalpha2b is a well-tolerated and effective therapy for hemangiomas of the head and neck that require intervention.

Adolescent↗
PubMed1996

Detection of hepatocellular carcinoma in cirrhotic patients: sensitivity of CT and ultrasonography.

Patients with cirrhosis are at increased risk for the development of hepatocellular carcinoma. The heterogeneous hepatic parenchyma produced by cirrhosis makes detection of hepatomas more difficult. The purpose of this study was to determine the sensitivities of CT and ultrasonography for detecting hepatomas in cirrhotic patients. A retrospective analysis was performed of 733 patients who underwent liver transplantation at our institution. A study population of 21 patients was selected who met our inclusion criteria. The inclusion criteria required a pathologic diagnosis of hepatocellular carcinoma, pathologic evidence of cirrhosis, and contrast-enhanced CT and sonographic examinations performed within 1 week of each other. The sensitivities of CT and ultrasonography were determined by comparing the imaging findings with pathology findings from serially sectioned total hepatectomy specimens. A total of 40 hepatomas were detected pathologically in the 21 patients in our study population. CT identified 12 of 21 patients with hepatomas and detected 18 of 40 individual lesions (patient detection sensitivity = 57%, lesion detection sensitivity = 45%). Ultrasonography identified 14 of 21 patients with hepatomas and detected 21 of 40 individual lesions (patient detection sensitivity = 67%, lesion detection sensitivity = 51%). Combining the findings of CT and ultrasonography allowed identification of 17 of 21 patients with hepatomas and detection of 24 of 40 individual lesions (patient detection sensitivity = 80%, lesion detection sensitivity = 60%). We conclude that CT and ultrasonography have a low sensitivity for the detection of hepatocellular carcinoma in patients with cirrhosis.

Carcinoma, Hepatocellular↗
PubMed1996

Renovascular hypertension.

In current clinical practice, angiographic evaluation of patients with suspected renovascular hypertension usually follows clinical suspicion and positive captopril scintigraphy. Early digital angiography and percutaneous renal artery angioplasty have evolved as the accepted treatment pattern. Doppler sonography and MR angiography continue to be evaluated as potential methods of noninvasive screening.

Angioplasty, Balloon↗
PubMed1995

Orbital varix presenting as a subconjunctival mass.

A 39-year-old woman presented with a vermiform superior conjunctival mass that progressively enlarged during 4 years of follow-up. Although magnetic resonance imaging suggested that the lesion was located in the superior forniceal conjunctiva, surgical exploration disclosed a vascular anomaly (varix) that extended deep into the orbit. The clinical features and management of orbital varices are discussed.

Adult↗
PubMed1995

Efficacy of expiratory tracheal gas insufflation in a canine model of lung injury.

Tracheal gas insufflation (TGI) improves the efficiency of CO2 elimination by reducing the CO2-laden dead space of the airways. The effect of TGI on PaCO2 diminishes in the setting of acute lung injury (ALI) because an increased alveolar component dominates the total physiologic dead space. Nevertheless, adopting a strategy of permissive hypercapnia should partially offset the decreased efficacy of TGI by increasing CO2 concentration in the proximal airways. To examine these issues we studied the CO2 removal efficacy of expiratory TGI as an adjunct to conventional mechanical ventilation (CMV) before and after oleic acid-induced lung injury (OAI). We first examined the effect of TGI before and after OAI, keeping tidal volume (VT) and frequency constant, and allowing PaCO2 to increase after OAI. We then tested TGI efficiency after matching PaCO2 after OAI to its pre-OAI level by increasing VT (post-OA/VT stage). PaCO2 was 53 +/- 3, 79 +/- 21, and 52 +/- 4 mm Hg in the pre-OAI, post-OAI, and post-OA/VT stages of CMV, respectively. The corresponding decrements in PaCO2 produced by TGI at a flow rate of 10 L/min were 16 +/- 3, 24 +/- 10, and 10 +/- 2 mm Hg, respectively. TGI decreased total physiologic dead space per breath (VD) by 56, 31, and 28 ml during the pre-OAI, post-OAI, and post-OA/VT stages, respectively. Despite a smaller reduction in VD during the post-OAI stage, the effect of TGI on PaCO2 was preserved because of the relatively high PaCO2 prior to its initiation.(ABSTRACT TRUNCATED AT 250 WORDS)

Air↗
PubMed1995

Mismatched bone marrow transplantation for Omenn syndrome: a variant of severe combined immunodeficiency.

Omenn syndrome is a variant of SCID, inherited as an autosomal recessive disorder, and characterized by severe eczematoid dermatitis, eosinophilia, elevated serum IgE and a distinctive histology in enlarged lymph nodes. The etiology of Omenn syndrome is unknown, however, unlike other forms of SCID; patients with Omenn syndrome have activated T lymphocytes in their circulation capable of non-MHC restricted cytotoxic function. Recently, it has been observed that the use of immunosuppressive therapy, particularly cyclosporine, can modify the clinical manifestations of the disorder. Prior to the use of bone marrow transplantation this disease was universally fatal. Death typically occurred in infancy as the result of opportunistic infections and/or malignancies, most notably lymphomas. While bone marrow transplantation has become quite successful for many phenotypes of SCID, even with the use of alternative donors other than histocompatible siblings, in Omenn syndrome it remains a challenge. In our experience, patients with Omenn syndrome exhibit a higher incidence of Gram negative sepsis, before and during transplantation, and carry a significant risk of post-transplant rejection when compared with patients with other phenotypes of SCID. We report the results of six patients treated with bone marrow transplantation from alternative donors, three had unrelated donors (URD) and three had haplo-identical parental donors. Five of the six patients achieved complete and/or durable donor cell engraftment and only one patient experienced acute GVHD. Three patients died of transplant-related complications (infection or EBV-associated B cell lymphoma) between day +22 and day +95 post-transplant. Three patients survived more than 1 year post-transplant.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Marrow Transplantation↗
PubMed1994

Immunoregulatory abnormalities in patients with Epstein-Barr virus-associated B cell lymphoproliferative disorders.

EBVirus-associated B cell lymphoproliferative disorder (BLPD) is a recognized complication of primary immunodeficiency and organ as well as bone marrow transplantation. Although the nature of the immune defects that predispose to the development of BLPD are unknown, it is postulated that aberrant T cell responses are involved. It is our hypothesis that unbalanced lymphokine production is a major contributory factor to abnormal B cell growth in response to EBV, resulting in BLPD. Since IFN-alpha and IL-4 are important regulators of B cell proliferation and also regulate the synthesis of IgE, we determined serum levels of IFN-alpha, IL-4, and IgE in 8 patients with newly diagnosed BLPD. Comparison was made to healthy recipients of organ transplants on immunosuppressive therapy without BLPD, and normal EBV seropositive controls. Levels of serum IL-4 were significantly elevated in both patients with BLPD as well as in healthy immunosuppressed organ transplant recipients as compared with normal healthy individuals. Patients with BLPD exhibited a combination of significantly lower levels of serum IFN-alpha, and significantly higher levels of serum IgE than either healthy EBV seropositive individuals or healthy recipients of organ transplants on immunosuppressive therapy. These results suggest that imbalance in the proportions of circulating cytokines favoring B cell proliferation may be contributing to the development of EBV-associated BLPD. The potential significance of the finding of low IFN-alpha in patients who develop BLPD is exemplified by our recent success in the treatment of BLPD with IFN-alpha and intravenous IgG.

Adolescent↗
PubMed1994

Willingness to perform euthanasia. A survey of physician attitudes.

BACKGROUND: In the United States, few studies have examined important variables in physician attitudes toward the practice of euthanasia, such as the patient's underlying disease, mental capacity, and age, and the physician's specialty and religion. We administered a case-based survey to analyze the impact of such specific variables on physician attitudes toward the practice. METHODS: A four-section survey solicited (1) physician responses to three hypothetical cases in which patients requested euthanasia; (2) physicians' general opinions about euthanasia and how its legalization might affect them personally and professionally; and (3) demographic information. Analysis focused on physicians' characteristics as they related to their responses to the various aspects of euthanasia elicited in the survey. Univariate and multivariate analyses, using logistic regression, were performed. RESULTS: Completed and analyzable surveys were returned by 740 physicians. We found that physicians felt more comfortable with euthanasia requests from nondecisional, nonterminal patients who had left advance directives than they did with requests from decisional patients suffering from grave illnesses or injuries, or from decisional patients who had early signs of a progressive but nonlethal neurologic disease. We also found that physicians' specialties and religions correlated with their responses to the hypothetical cases and with their generalized attitudes toward euthanasia. CONCLUSIONS: Given the disparity in responding physicians' attitudes toward euthanasia, along with the fact that values based on religious affiliation or profession may underlie many physicians' opposition to the practice, we conclude that if euthanasia is to be legalized, safeguards protective of patients and physicians must be incorporated.

Adult↗