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Biomedical subjects

J Goldstone

Publications and source records attributed to J Goldstone.

At least 19 recordsLinked to original sources
PubMed2002

The pulmonary physician in critical care. 10: difficult weaning.

The study of patients being weaned from mechanical ventilation has offered new insights into the physiology of respiratory failure. Assessment of the balance between respiratory muscle strength, work and central drive is essential if difficulty in weaning occurs, and optimisation of these elements may improve the success of weaning. Psychological support of patients and the creation of units specialising in weaning have also resulted in a higher success rate.

Critical Care↗
PubMed2001

A quantum adiabatic evolution algorithm applied to random instances of an NP-complete problem.

A quantum system will stay near its instantaneous ground state if the Hamiltonian that governs its evolution varies slowly enough. This quantum adiabatic behavior is the basis of a new class of algorithms for quantum computing. We tested one such algorithm by applying it to randomly generated hard instances of an NP-complete problem. For the small examples that we could simulate, the quantum adiabatic algorithm worked well, providing evidence that quantum computers (if large ones can be built) may be able to outperform ordinary computers on hard sets of instances of NP-complete problems.

Journal Article↗
PubMed2001

Diagnosis and management of aortoenteric fistulas.

Development of an aortoenteric fistula (AEF) is a devastating and life-threatening condition, which is as difficult to diagnose as it is to treat. Fortunately, it is rare, most commonly seen as a delayed complication of aortic reconstruction. Two types are recognized: primary and secondary. Primary fistulas occur de novo between the aorta and bowel, most commonly duodenum. Secondary fistulas occur between an aortic graft and segment of bowel. Diagnosis of AEF requires a high index of suspicion in patients who present with either signs of infection or gastrointestinal hemorrhage. Early diagnosis is essential for a successful outcome because of the lethal nature of AEF. Symptomatology can be varied but most often includes signs of infection and of gastrointestinal bleeding. Esophagogastroduodenoscopy (EGD) and computed tomography (CT) scans are the most useful tests to diagnose AEF. Treatment almost always requires excision of the infected graft and revascularization. Placement of an extra anatomic bypass, followed by graft excision, has been the usual treatment. Recent experience with in situ revascularization has shown that a variety of materials can be use for in situ reconstruction with good results. Morbidity and mortality rates still are high even in contemporary series. The mortality rate still is approximately 33%, but amputation rates have been reduced to less then 10%. Care of patients with AEF requires timely control of bleeding and infection followed by vascular reconstruction performed in a manor to minimize physiological stress.

Aortic Diseases↗
PubMed2001

Aortic aneurysm resulting from umbilical artery catheterization: case report, literature review, and management algorithm.

Aortic aneurysms in infants and children are quite rare. The use of umbilical artery catheters in the management of critically ill neonates has been associated with infection and subsequent aneurysm formation. There have been 46 cases reported (including our own); most of the aneurysms have been located in the abdominal aorta and have displayed saccular morphology. Through an analysis of the literature, we identified two factors that had significant correlation with improved survival: diagnosis before surgery and surgical repair (P <.05). This report presents the case of a 23-day-old neonate with an abdominal aortic aneurysm and hypertension. On the basis of our literature review, we offer a management algorithm for this rare but very serious complication of umbilical artery catheterization.

Algorithms↗
PubMed1999

Esophageal-directed pressure support ventilation in normal volunteers.

STUDY OBJECTIVES: To ascertain whether inspiratory pressure support (IPS) can be triggered reliably from and targeted at esophageal pressures (Pes), and to compare the work of breathing and time delay to initiation of inspiratory flow between conventional pressure support and esophageal-directed pressure support (EDPS). DESIGN: Prospective laboratory study. SETTING: University medical school. PATIENTS OR PARTICIPANTS: Five normal volunteers. INTERVENTIONS: IPS at a level to achieve tidal volume of 10 mL/kg, and EDPS with a target Pes of 0 cm H2O via full facemask. MEASUREMENTS AND RESULTS: Pes, airway pressure, and inspiratory flow were measured during spontaneous breathing. Peak Pes and pressure time product (PTP) of Pes were calculated during spontaneous breathing and through linear resistances. Measurements were repeated during IPS and EDPS ventilation. At rest, PTP was 7.56 (+/- 3.6) and peak Pes was -5.8 cm H2O (+/- 1.44). When subjects were breathing through the resistors, PTP increased to 12.4 (+/- 8.1) and 30.3 (+/- 8.9) and peak Pes decreased to -7.2 and -15.3 cm H2O respectively. With facemask IPS, unloaded PTP fell to 1.7 (+/- 1.3) and peak Pes fell to -3.3 cm H2O (+/- 1.3). When ventilated through the highest resistance with IPS, mean PTP increased to 21.9 and peak Pes increased to -11.9 (+/- 4.2) cm H2O relative to baseline. During EDPS with the resistor, PTP fell to 1.5+/-1.1 (p < 0.007) and peak Pes fell to -1.9+/-1.1 cm H2O (p < 0.0001). CONCLUSIONS: It was possible to initiate supported breathing from Pes values. The work performed, as measured by PTP, was lower during EDPS than during either unsupported breathing or conventional IPS.

Feasibility Studies↗
PubMed1997

Status of lipids as a risk factor for stroke.

There is mounting epidemiologic evidence to support the relationship of lipids as a risk factor for ischemic stroke. We review epidemiologic and pathophysiologic evidence for such a link. Treatment of hyperlipidemia is addressed within the context of overall cardiovascular disease risk but also for stroke prevention.

Arteriosclerosis↗
PubMed1996

Use of near infrared spectroscopy to estimate cerebral blood flow in conscious and anaesthetized adult subjects.

Near infrared spectroscopy (NIRS) can be used to quantify cerebral haemodynamic states non-invasively and to estimate cerebral blood flow (CBF). In the first part of this study we have compared CBF measurements in conscious and anaesthetized subjects. In the second part we have compared paired measurements made during anaesthesia, first on the scalp and then the dura after craniotomy. Mean CBF was 17 (SD 7) ml 100 g-1 min-1 in the conscious subjects compared with 21 (8) ml 100 g-1 min-1 on the scalp during anaesthesia (P > 0.1). Mean CBF on the dura was 68 (21) ml 100 g-1 min-1 (P < 0.0001). Computer modelling suggests that the difference in magnitude between scalp and dura measurements of CBF is likely to be caused by the optical effect of extracerebral tissue which powerfully scatters light passing through it but does not contribute significantly to the measured CBF because it has only a small blood content itself. The results lend support to this method of estimating CBF although formal validation by comparison with an established technique is needed.

Adult↗
PubMed1995

Guidelines for carotid endarterectomy. A multidisciplinary consensus statement from the Ad Hoc Committee, American Heart Association.

BACKGROUND AND PURPOSE: Indications for carotid endarterectomy have engendered considerable debate among experts and have resulted in publication of retrospective reviews, natural history studies, audits of community practice, position papers, expert opinion statements, and finally prospective randomized trials. The American Heart Association assembled a group of experts in a multidisciplinary consensus conference to develop this statement. METHODS: A conference was held July 16-18, 1993, in Park City, Utah, that included recognized experts in neurology, neurosurgery, vascular surgery, and healthcare planning. A program of critical topics was developed, and each expert presented a talk and provided the chairman with a summary statement. From these summary statements a document was developed and edited onsite to achieve consensus before final revision. RESULTS: The first section of this document reviews the natural history, methods of patient evaluation, options for medical management, results of surgical management, data from position statements, and results to date of prospective randomized trials for symptomatic and asymptomatic patients with carotid artery disease. The second section divides 96 potential indications for carotid endarterectomy, based on surgical risk, into four categories: (1) Proven: This is the strongest indication for carotid endarterectomy; data are supported by results of prospective contemporary randomized trials. (2) Acceptable but not proven: a good indication for operation; supported by promising but not scientifically certain data. (3) Uncertain: Data are insufficient to define the risk/benefit ratio. (4) Proven inappropriate: Current data are adequate to show that the risk of surgery outweighs any benefit. CONCLUSIONS: Indications for carotid endarterectomy in symptomatic good-risk patients with a surgeon whose surgical morbidity and mortality rate is less than 6% are as follows. (1) Proven: one or more TIAs in the past 6 months and carotid stenosis > or = 70% or mild stroke within 6 months and a carotid stenosis > or = 70%; (2) acceptable but not proven: TIAs within the past 6 months and a stenosis 50% to 69%, progressive stroke and a stenosis > or = 70%, mild or moderate stroke in the past 6 months and a stenosis 50% to 69%, or carotid endarterectomy ipsilateral to TIAs and a stenosis > or = 70% combined with required coronary artery bypass grafting; (3) uncertain: TIAs with a stenosis < 50%, mild stroke and stenosis < 50%, TIAs with a stenosis < 70% combined with coronary artery bypass grafting, or symptomatic, acute carotid thrombosis; (4) proven inappropriate: moderate stroke with stenosis < 50%, not on aspirin; single TIA, < 50% stenosis, not on aspirin; high-risk patient with multiple TIAs, not on aspirin, stenosis < 50%; high-risk patient, mild or moderate stroke, stenosis < 50%, not on aspirin; global ischemic symptoms with stenosis < 50%; acute dissection, asymptomatic on heparin. Indications for carotid endarterectomy in asymptomatic good-risk patients performed by a surgeon whose surgical morbidity and mortality rate is less than 3% are as follows. (1) Proven: none. As this statement went to press, the National Institute of Neurological Disorders and Stroke issued a clinical advisory stating that the Institute has halted the Asymptomatic Carotid Atherosclerosis Study (ACAS) because of a clear benefit in favor of surgery for patients with carotid stenosis > or = 60% as measured by diameter reduction. When the ACAS report is published, this indication will be recategorized as proven. (2) acceptable but not proven: stenosis > 75% by linear diameter; (3) uncertain: stenosis > 75% in a high-risk patient/surgeon (surgical morbidity and mortality rate > 3%), combined carotid/coronary operations, or ulcerative lesions without hemodynamically significant stenosis; (4) proven inappropriate: operations with a combined stroke morbidity and mortality > 5%.

Arterial Occlusive Diseases↗
PubMed1995

Secondary aortoenteric fistula: contemporary outcome with use of extraanatomic bypass and infected graft excision.

PURPOSE: The standard treatment for secondary aortoenteric fistula (SAEF) has been infected graft removal (IGR) and extraanatomic bypass (EAB), an approach criticized for its high rate of death, amputation, and disruption of aortic closure. Recently, graft excision and in situ graft replacement has been proposed as a safer treatment alternative. Because the current outcome that can be achieved by use of the standard treatment of SAEF has really not been established, we reviewed the records of 33 patients treated for SAEF at our institution during a contemporary time interval (1980 to 1992). METHODS: Thirteen patients (39.4%) were admitted with evidence of gastrointestinal bleeding and infection, whereas nine (27.3%) only had bleeding, 10 (30.3%) only had signs of infection, and one SAEF was entirely occult (graft thrombosis). Four patients required emergency operation. The fistula type was anastomotic in 13 (39.4%) patients, paraprosthetic in 15 (45.5%), and not specified in 4 cases. Thirty-two patients underwent EAB followed immediately by IGR (n = 16, 48.5%) or followed by IGR after a short interval, averaging 3.9 days (n = 16, 48.5%). The final patient underwent IGR, followed by EAB. RESULTS: Follow-up on 31 patients (93.9%) averaged 4.4 +/- 3.7 years. There were nine deaths (27.3%) resulting from the SAEF, six perioperative and three late. Three patients (9.1%) had disrupted aortic closure. There were four amputations in three patients (9.1%), two perioperative and two late. Late EAB infection occurred in five patients (15.2%), leading to one death and one amputation. EAB failure occurred in six patients, two during operation and four late, leading to one amputation. The cumulative cure rate for this SAEF group was 70% at 3 years and thereafter. Compared with our earlier SAEF experience, this is a decline of 21% in the mortality rate, 19% in aortic disruption, and 27% in limb loss. CONCLUSIONS: We conclude that outcome reports based on SAEF series extending over long time intervals do not accurately represent the results that are currently achieved with standard SAEF treatment with use of EAB plus IGR. This improved outcome is attributed to wide debridement of infected tissue beds, reduced intervals of lower body ischemia, and advances in perioperative management. To determine whether any new treatment approach actually offers improved outcome in the management of SAEF, comparison with EAB plus IGR should be limited to patients treated within the last decade at most.

Aged↗
PubMed1995

Histopathological characteristics of explanted human prosthetic arterial grafts: implications for the prevention and management of graft infection.

OBJECTIVE: to study the histopathological characteristics of prosthetic vascular graft infection. DESIGN: prospective clinical study over 2 years. SETTING: University Hospital. MATERIALS: 36 infected and 29 uninfected (control) chronically implanted vascular prostheses (half aortic) were removed and 352 sections prepared. CHIEF OUTCOME MEASURES: light microscopy (multiple stains), scanning electron microscopy (SEM), and multiple culture techniques to identify characteristics of healing, infection, and microorganisms. MAIN RESULTS: Acute inflammation (AI) (neurophils, granulocytes and necrosis) were seen in 75% of infected grafts, were most prominent in the perigraft tissue and rarely seen on the luminal surface. These were usually well localised, leaving the remainder of a graft well incorporated with no signs of infection. In 25% of clinically infected, culture-positive grafts there was no significant acute inflammation. Chronic inflammation (CI) (macrophages, lymphocytes, monocytes, giant cells) was seen in 70% of both control and infected grafts. In 50% of both groups a significant lymphocytic population was composed exclusively of T-lymphocytes suggesting a true host vs graft response. Unincorporated chronically implanted grafts (> 1 yr) were seen with equal frequency in the two groups although more diffusely unincorporated grafts were infected. Microorganisms were cultured from 23 infected grafts (64%) and were, at microscopy, mostly found outside the graft and nerves on the luminal side. CONCLUSIONS: This data cast doubt on criteria commonly used to distinguish graft infections and host vs. graft reactions from normal graft healing. Acute and chronic inflammation are not predictive of infection.

Acute Disease↗
PubMed1995

Guidelines for carotid endarterectomy. A multidisciplinary consensus statement from the ad hoc Committee, American Heart Association.

BACKGROUND AND PURPOSE: Indications for carotid endarterectomy have engendered considerable debate among experts and have resulted in publication of retrospective reviews, natural history studies, audits of community practice, position papers, expert opinion statements, and finally prospective randomized trials. The American Heart Association assembled a group of experts in a multidisciplinary consensus conference to develop this statement. METHODS: A conference was held July 16-18, 1993, in Park City, Utah, that included recognized experts in neurology, neurosurgery, vascular surgery, and healthcare planning. A program of critical topics was developed, and each expert presented a talk and provided the chairman with a summary statement. From these summary statements a document was developed and edited onsite to achieve consensus before final revision. RESULTS: The first section of this document reviews the natural history, methods of patient evaluation, options for medical management, results of surgical management, data from position statements, and results to date of prospective randomized trials for symptomatic and asymptomatic patients with carotid artery disease. The second section divides 96 potential indications for carotid endarterectomy, based on surgical risk, into four categories: (1) Proven: This is the strongest indication for carotid endarterectomy; data are supported by results of prospective contemporary randomized trials. (2) Acceptable but not proven: a good indication for operation; supported by promising but not scientifically certain data. (3) Uncertain: Data are insufficient to define the risk/benefit ratio. (4) Proven inappropriate: Current data are adequate to show that the risk of surgery outweighs any benefit. CONCLUSIONS: Indications for carotid endarterectomy in symptomatic good-risk patients with a surgeon whose surgical morbidity and mortality rate is less than 6% are as follows. (1) Proven: one or more TIAs in the past 6 months and carotid stenosis > or = 70% or mild stroke within 6 months and a carotid stenosis > or = 70%; (2) acceptable but not proven: TIAs within the past 6 months and a stenosis 50% to 69%, progressive stroke and a stenosis > or = 70%, mild or moderate stroke in the past 6 months and a stenosis 50% to 69%, or carotid endarterectomy ipsilateral to TIAs and a stenosis > or = 70% combined with required coronary artery bypass grafting; (3) uncertain: TIAs with a stenosis < 50%, mild stroke and stenosis < 50%, TIAs with a stenosis < 70% combined with coronary artery bypass grafting, or symptomatic, acute carotid thrombosis; (4) proven inappropriate: moderate stroke with stenosis < 50%, not on aspirin; single TIA, < 50% stenosis, not on aspirin; high-risk patient with multiple TIAs, not on aspirin, stenosis < 50%; high-risk patient, mild or moderate stroke, stenosis < 50%, not on aspirin; global ischemic symptoms with stenosis < 50%; acute dissection, asymptomatic on heparin. Indications for carotid endarterectomy in asymptomatic good-risk patients performed by a surgeon whose surgical morbidity and mortality rate is less than 3% are as follows. (1) Proven: none. (As this statement went to press, the National Institute of Neurological Disorders and Stroke issued a clinical advisory stating that the Institute has halted the Asymptomatic Carotid Atherosclerosis Study (ACAS) because of a clear benefit in favor of surgery for patients with carotid stenosis > or = 60% as measured by diameter reduction. When the ACAS report is published, this indication will be recategorized as proven. (2) acceptable but not proven: stenosis > 75% by linear diameter; (3) uncertain; stenosis > 75% in a high-risk patient/surgeon (surgical morbidity and mortality rate > 3%), combined carotid/coronary operations, or ulcerative lesions without hemodynamically significant stenosis; (4) proven inappropriate: operations with a combined stroke morbidity and mortality > 5%.

Aspirin↗