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Biomedical subjects

M C Barry

Publications and source records attributed to M C Barry.

At least 19 recordsLinked to original sources
PubMed2006

The effect of perioperative beta-blockade on the pulmonary function of patients undergoing major arterial surgery.

INTRODUCTION: Concern about the potential detrimental side-effects of beta-blockade on pulmonary function often dissuades against their perioperative use in patients undergoing major arterial surgery (especially in those with chronic obstructive pulmonary disease (COPD)). In this study we aimed to establish prospectively the clinical relevance of these concerns. METHODS: After ethics committee approval and individual informed consent, the pulmonary function of twenty patients (mean age 68.7 years (range 43-82), 11 males) scheduled to undergo non-emergency major vascular surgery was studied by recording symptoms and spirometry before and after institution of effective beta-blockade. Fifteen patients (75%) had significant smoking histories (mean pack years/patient=50), while 12 (60%) had COPD. RESULTS: All patients tolerated effective beta-blockade satisfactorily without developing either subjective deterioration in symptoms or significant change on spirometry. The mean change in FEV1 following adequate beta-blockade was 0.05+/-0.24 liters (95% CI -0.06 to +1.61), p=0.35, giving a mean percentage change of 3.18%+/-11.66 (95% CI -2.26 to 8.62). CONCLUSIONS: Previously held concerns about worsening pulmonary function through the short-term use of beta-blockers should not dissuade their perioperative usage in patients with peripheral vascular disease. Furthermore, the accuracy of pulmonary function tests in preoperative assessment and risk stratification also appears unaffected by this therapy.

Adrenergic beta-Antagonists↗
PubMed2004

Current diagnosis and management of blunt internal carotid artery injury.

BACKGROUND: Blunt carotid artery injury (BCI) is a rare but potentially devastating injury. When undiagnosed it can result in severe disability or death. METHODS: A Medline-based literature search was performed using key words 'blunt carotid injury' and cross-referenced with further original papers obtained from the references from this search. RESULTS AND CONCLUSIONS: The incidence of BCI is very low. However, given the serious consequences of a missed injury, recent efforts have focussed on targeted screening for this injury in trauma patients. Conventional angiography remains the investigation of choice but may be superceded in the future by non-invasive methods such as magnetic resonance angiography or CT angiography. Operative intervention is rarely required and anti-coagulation remains the treatment of choice where dissection or pseudoaneurysm is diagnosed. The role of anti-platelet therapy is currently being investigated. Endovascular management using stents has been described but medium to long term results are not yet available.

Anticoagulants↗
PubMed2004

Radiation-induced femoral arteritis.

Radiation arteritis is currently an uncommon sequalae of external beam radiation, however because of the increasing use of radiotherapy in the management of neoplastic conditions its recognition is increasingly important. We present two cases of debilitating femoral occlusive disease, secondary to radiation exposure, at a long period post irradiation and review the pathophysiolgy and management options for this condition.

Adult↗
PubMed2001

Preoperative treatment with recombinant human growth hormone prevents ischemia reperfusion-induced diaphragmatic dysfunction.

BACKGROUND: Respiratory complications continue to be a major cause of morbidity and mortality following major vascular surgery. The recent UK Small Aneurysm Trial cited preoperative respiratory function as the major predictor of outcome following elective aortic surgery. AIM: The aim of this study was to investigate the effect of aortic clamping and revascularization on diaphragmatic muscle function in a small animal model and to evaluate the role of preoperative treatment with recombinant human growth hormone (rhGH) in preventing diaphragmatic muscle dysfunction. METHODS: Male Sprague-Dawley rats (n = 18) were randomized into one of three groups: control (n = 6) underwent laparotomy only; IR (n = 6) had a laparotomy with infrarenal cross-clamping for 30 min followed by lower torso revascularization for 2 h; IR + rhGH (n = 6) were treated with rhGH (Genotropin 0.3 IU/kg/day) for 5 days before laparotomy and aortic cross-clamping for 30 min followed by lower torso revascularization for 2 h. Diaphragmatic muscle contractile function was assessed ex vivo using electrical field stimulation in a tissue bath. RESULTS: Two hours of IR injury resulted in a significant impairment in diaphragmatic twitch (Control, 242.01 + 38.45 g; IR, 108.55 + 7.15 g). This impairment was prevented by pretreatment with rhGH (rhGH, 319.14 + 30.71 g; P < 0.01). Tetanic function was also significantly impaired by ischemia reperfusion injury (control, 605 + 77.63 g; IR, 228.12 + 14.38 g). Again, pretreatment with rhGH prevented this deterioration (IR + rhGH, 704.39 + 45.69 g; P < 0.05) compared with controls. CONCLUSION: The results of this study suggest that preoperative administration of rhGH may have a role in preventing the diaphragmatic dysfunction associated with infrarenal aortic cross-clamping and revascularization.

Animals↗
PubMed2001

Carotid stump syndrome: outcome from surgical management.

OBJECTIVES: in patients with occluded internal carotid arteries the carotid stump is a potential source of microemboli resulting in the persistence of retinal or cerebral ischaemic symptoms. We report 25 patients who had persistent cerebral and retinal ischaemic symptoms with an occluded ipsilateral ICA and a carotid stump who underwent surgical exclusion of the stump. METHODS: between January 1988 and January 1998, 332 patients underwent carotid endarterectomy. Twenty-five patients (20 males: five females; mean age 58.9 (range 44-78 years)) had carotid stump exclusion. Indications for surgery were transient ischaemic attack (22), amaurosis fugax (eight) and cerebrovascular accident (13). Three patients had undergone contralateral carotid endarterectomy and 12 had significant contralateral stenosis. Twenty patients were being treated with aspirin and four with warfarin at the time of presentation. RESULTS: the diagnosis of carotid stump was made in 22 patients by angiography. In the remaining three patients duplex alone was diagnostic in two patients. In the third case duplex was combined with magnetic resonance angiography (MRA) to confirm the diagnosis. Stump exclusion was carried out by oversewing the ICA origin. All but one patient remained symptom free at follow-up. CONCLUSION: carotid stump syndrome should be considered as a likely clinical entity in patients with an occluded ICA and persisting cerebral and retinal microembolic symptoms. Surgical exclusion of the carotid stump is a safe and effective method of treatment.

Adult↗
PubMed1998

The effects of recombinant human growth hormone on cardiopulmonary function in elective abdominal aortic aneurysm repair.

OBJECTIVES: Cardiorespiratory complications are the predominant source of morbidity in patients undergoing major surgery. Recombinant human growth hormone (rhGH) has previously been shown to be effective in improving respiratory and cardiac function in compromised patients. DESIGN: The aim of this study was to assess the effects of perioperative rhGH on cardiac function in 33 patients undergoing elective infrarenal abdominal aortic aneurysm repair. METHODS: Patients were randomised to one of three groups: placebo for 6 days before and after surgery (control, n = 12); genotropin (GH) 0.3 units/kg/day for 6 days before and after surgery (pre and postop GH, n = 10) and placebo for 6 days before and GH (0.3 units/kg/day) for 6 days after surgery (postop EH, n = 11). Patients were assessed on days 7 and 1 before and days 7, 14 and 50 after operation. Intraoperative cardiac index (CI) was measured after induction of anaesthesia, before and after aortic cross-clamping, after aortic unclamping and at the end of surgery. RESULTS: Pretreatment with GH resulted in a significantly higher heart rate during surgery and was associated with a trend towards higher cardiac index (CI) (p < 0.067) at all stages of surgery. Mean arterial blood pressure at the stage of aortic unclamping was significantly higher in patients treated with GH preoperatively. CONCLUSIONS: Larger studies are required to evaluate the beneficial effects of GH in aortic surgery. However, data from this pilot study suggests that perioperative GH administration may result in improved cardiac performance during aortic surgery.

Aged↗
PubMed1998

An "all comers" policy for ruptured abdominal aortic aneurysms: how can results be improved?

OBJECTIVE: To review our experience of a non-selective policy for the treatment of ruptured abdominal aortic aneurysm to see if the policy was justified, and to identify any preoperative risk factors that adversely influenced outcome. DESIGN: Retrospective study. SETTING: Teaching hospital, Republic of Ireland. SUBJECTS: 258 patients admitted with abdominal aortic aneurysms between January 1982 and December 1993. INTERVENTIONS: Definitive surgical treatment. MAIN OUTCOME MEASURES: Morbidity, mortality, and risk factors. RESULTS: In-hospital mortality for all patients was 43% (110/258). Overall, women did worse than men (28/44, 64%, died, compared with 96/214, 45%, p=0.03). The mortality among patients over the age of 80 (23/45, 51%) was not significantly different from that among younger patients (97/202, 48%). Blood pressure, platelet count, and haemoglobin concentration were all significantly lower preoperatively among those who died (p < 0.05). CONCLUSIONS: Age alone cannot be used to justify witholding definitive surgical treatment. Treatment should be aimed towards reversing haematological and haemodynamic abnormalities preoperatively to try to improve outcome.

Aged↗
PubMed1998

Quality of life following repair of ruptured and elective abdominal aortic aneurysms.

OBJECTIVE: To find out whether patients undergoing repair of ruptured abdominal aortic aneurysms (AAA) had more emotional problems and limitations of lifestyle than those listed for elective resection. DESIGN: Retrospective study SETTING: Teaching hospital, Eire. SUBJETS: 28 patients, 14 in each group, matched for age, sex, duration of stay in the intensive care unit (ICU), hospital stay postoperatively, and length of time since operation. INTERVENTIONS: Application of structured questionnaire. MAIN OUTCOME MEASURES: Emotional problems, mobility, activities of daily living, ability to sleep, degree of psychological stress, presence of symptoms, and Rosser index to measure quality of life (QoL). RESULTS: There were no significant differences between the groups in any measure. CONCLUSIONS: Patients have few emotional difficulties or disturbances of QoL after emergency or elective repair of AAA. Survivors after repair of ruptured AAA can expect as good a quality of life as those operated on electively. These results support an aggressive approach to the treatment of ruptured AAA.

Aged↗
PubMed1998

Evaluation and application of the Cornell Net Carbohydrate and Protein System for dairy cows fed diets based on pasture.

This study evaluated the Cornell Net Carbohydrate and Protein System for dairy cows consuming diets based on pasture, assessed the sensitivity of the model to critical inputs, and demonstrated application opportunities. Data were obtained from four grazing experiments and four indoor pasture feeding experiments (25 dietary treatments) involving dairy cows in New Zealand and the US. The model provided a reasonably good estimate of changes in body condition score (r2 = 0.78; slope not significantly different from 1), estimated energy balance (r2 = 0.76; slope not significantly different from 1), blood urea N (r2 = 0.94; underprediction bias of 0.5%), microbial N flow (r2 = 0.88; slope not significantly different from 1), and milk production. The model underpredicted dry matter intake (r2 = 0.80; 13% bias) and overpredicted ruminal pH (r2 = 0.47; 1.7% bias). Predicted milk production was especially sensitive to changes in pasture lignin content, effective fiber, rate of fiber digestion, and amino acid composition of ruminal microbes. Milk production was first-limited by the supply of metabolizable energy when only high quality pasture was fed, but specific amino acids limited milk production when more than 20% of the diet consisted of a grain supplement. These results indicate that the Cornell Net Carbohydrate and Protein System can be used for dairy cows in a grazing system to make realistic predictions of performance.

Amino Acids↗
PubMed1997

Differential effects of lower limb revascularisation on organ injury and the role of the amino acid taurine.

Lower torso revascularisation following ischaemia results in a systemic inflammatory response. Endothelial barrier function is disrupted by neutrophil-derived proteases and oxidants. Taurine, an amino acid found in large quantities in neutrophils, is a powerful endogeneous anti-oxidant. The aims of this study were to investigate the systemic effects of reperfusion following lower limb revascularisation and to evaluate the role of taurine administration in preventing this injury. A rat model of aortic occlusion (30 min) followed by 2 h of reperfusion was used. Animals were randomised to one of three groups (n = 10 per group): control; ischaemia reperfusion untreated (IR) and taurine-treated. Taurine (4% solution) was administrated orally for 48 h prior to the experiment. Neutrophil infiltration and microvascular permeability were assessed by measuring tissue myeloperoxidase activity and wet/dry weights respectively in lung, liver, kidney, and in cardiac and skeletal muscle. Statistical analysis was by means of analysis of variance (ANOVA). Reperfusion resulted in pulmonary and renal microvascular injury as assessed by organ oedema. Hepatic tissue, skeletal and cardiac muscle were unaffected by lower limb revascularisation. Taurine was effective in preventing neutrophil-mediated pulmonary but not renal microvascular injury. These data suggest that, whilst reperfusion-induced pulmonary injury is predominantly neutrophil-mediated, agents other than neutrophil-derived oxidative metabolites, capable of independently causing organ injury through direct endothelial damage, are produced during reperfusion.

Animals↗
PubMed1997

Plasma factors augment neutrophil and endothelial cell activation during aortic surgery.

Lung injury following reperfusion results from endothelial damage caused by release of cytotoxic products by activated neutrophils (PMN) in the pulmonary microvasculature. This process is facilitated by the release of pro-inflammatory cytokines and arachidonic metabolites following the outset of reperfusion. This study aimed to evaluate the effect of plasma obtained before and after revascularisation on neutrophil and endothelial cell activation. Plasma (IR-plasma) was obtained from venous blood samples taken before and during aortic cross-clamping, and 5, 40 and 60 min following clamp removal in seven patients undergoing elective infrarenal aortic aneurysm resection. PMN from healthy volunteers (n = 5) were incubated with these plasma samples or with fMLP (N-formylmethionyl-leucyl-phenylalanine) as positive control for 30 min and assessed flow-cytometrically for CD11b expression. Human endothelial cells (ECV-304) were incubated with IR plasma for 2, 4 and 6 h or with tumour necrosis factor (TNF) (20 ng/ml) as positive control and assessed for ICAM-1 expression. Incubation with IR plasma resulted in a significant increase from pre-clamp in PMN CD11b expression. A similar trend was seen in endothelial cell ICAM-1 expression following 2 h incubation. These results indicate that reperfusion-induced endothelial dysfunction may be mediated by plasma factors released upon revascularisation which facilitate neutrophil-endothelial interaction through up-regulation of adhesion receptor expression.

Analysis of Variance↗
PubMed1997

Ruptured abdominal aortic aneurysm--can treatment costs and outcomes be predicted by using clinical or physiological parameters?

Mortality rates for patients undergoing surgery for ruptured abdominal aortic aneurysm (RAAA) remain high. The high cost of providing care for these patients mandates that proposed treatment protocols be evaluated for their cost-effectiveness. This study assessed costs related to outcome in different groups of patients with RAAA. From July 1987 to December 1993, 140 patients underwent emergency surgery for RAAA. Complete data on preoperative haemodynamic status, blood transfusion requirements, intensive care unit (ICU) stay and other hospital costs was available for 94 patients. Seventy-seven males (mean age 71.6(6)) and 17 females (mean age 77.2(6)) underwent surgery. Known risk factors including age (< or > 70 years), shock on admission (systolic blood pressure (BP) < or > 90 mm Hg), sex, and acute renal failure were analysed. For the purpose of comparison, costs (Pounds) were assessed by the ESRI (Economic and Social Research Institute of Ireland) based on 1992 prices. The overall survival rate was 48%: 53% among males and 24% among females (p < 0.05, Chi-squared test). In addition to having a significantly worse outcome than males, female patients with RAAA also had longer hospital and ICU stays and this was reflected in significantly greater expenditure. Similarly, male patients > 70 years old presenting with haemodynamic instability had significantly longer hospital and ICU stays than younger male patients. The average cost per RAAA survival (12,945 Pounds) in this series is not prohibitive, and the greater cost in high risk groups should not discourage intervention.

Acute Kidney Injury↗
PubMed1997

Immunological and physiological responses to aortic surgery: effect of reperfusion on neutrophil and monocyte activation and pulmonary function.

BACKGROUND: The aims of this study were to evaluate the effects of aortic clamping and unclamping on neutrophil and monocyte activation and release of plasma mediators in 20 patients undergoing elective aortic aneurysm surgery, and to correlate these findings with pulmonary haemodynamics and gas exchange. METHODS: Simultaneous arterial and mixed venous samples were obtained during and after aortic clamping and unclamping. RESULTS: Neutrophil respiratory burst activity in mixed venous samples increased significantly during the period of aortic clamping. An initial increase in neutrophil CD11b expression in venous blood 5 min after clamp removal was followed by a significant decrease in level of expression. Plasma tumour necrosis factor levels increased at the end of the cross-clamp period and reached a maximum 60 min following reperfusion. There was a significant and sustained rise in plasma thromboxane B2 levels following clamp removal. This increase correlated with the development of increased pulmonary vascular resistance. CONCLUSION: This study confirms the central role played by activated neutrophils in the early stages of reperfusion injury and also suggests a role for plasma mediators in mediating cardiopulmonary dysfunction during major vascular surgery.

Aged↗
PubMed1997

Pre-operative neutrophil and monocyte activation state predicts post-operative neutrophil and monocyte function.

OBJECTIVE: To find out if the in vitro responses of neutrophils (PMN) and monocytes preoperatively can predict their activation postoperatively. DESIGN: Prospective open study. SETTING: Teaching hospital, Ireland. SUBJECTS: 46 Patients (32 men, 14 women, mean age 65 years, range 33-85) who were to undergo elective major vascular or gastrointestinal operations for benign (n = 18) or malignant (n = 28) diseases. INTERVENTIONS: Measurement by flow cytometry of functional (PMN and monocyte respiratory burst activity) and phenotypic (expression of PMN CD 11b adhesion receptors and monocyte CD14 receptors) markers of activation. MAIN OUTCOME MEASURES: Correlation between mean channel fluorescence (MCF) preoperatively and postoperatively. RESULTS: In 24 patients PMN respiratory burst activity was increased before operation and had decreased significantly (p < 0.01) on postoperative day 1 (high responders group). In the remaining 22 patients (low responders group) respiratory burst activity was low before operation and had increased significantly (p < 0.05) on postoperative day 1. PMN CD 11b activity followed a similar trend. Monocyte activity responded similarly (in the high group mean (SEM) MCF preoperatively was 69.14 (13.15) compared with 58.23 (10.8) on day 1, and in the low group the corresponding figures were 38.5 (7.01) and 8.43 (5.2). Expression of CD14 did not differ between the groups and was less postoperatively than preoperatively. The groups did not differ in age, sex, APACHE 11 scores, smoking habits or types of disease and there was no major infective complications in either group. CONCLUSION: There are two distinct patterns of PMN and monocyte responses to injury that are independant of age, sex and severity of operation. These may be associated with the degree of stress preoperatively or with genetic factors.

Adult↗