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Biomedical subjects

Christopher S Baker

Publications and source records attributed to Christopher S Baker.

5 recordsLinked to original sources
PubMed2006

Occurrence of regional left ventricular dysfunction in patients undergoing standard and biofeedback dialysis.

BACKGROUND: Cardiac failure and cardiovascular death are extremely prevalent in dialysis patients. Recurrent subclinical myocardial ischemia is important in the genesis of heart failure in nondialysis patients. We examined whether this phenomenon occurs in response to the stress of hemodialysis (HD). METHODS: Eight patients prone to intradialytic hypotension were recruited for a randomized crossover study to compare the development of left ventricular regional wall motion abnormalities during standard (HD) and biofeedback dialysis. Patients underwent serial echocardiography with quantitative analysis to assess ejection fraction and regional left ventricular systolic function during both types of dialysis. Blood pressure and hemodynamic variables also were measured by using continuous pulse wave analysis. RESULTS: Forty-two new regional wall motion abnormalities developed in all 8 patients during HD compared with 23 regional wall motion abnormalities that developed in 7 patients during biofeedback dialysis (odds ratio, 1.8; 95% confidence interval, 1.1 to 3.0). The majority of regional wall motion abnormalities showed improvement in function by 30 minutes postdialysis. Overall mean regional function was significantly more impaired during HD (P = 0.022). At peak stress, ejection fraction (measured by percentage of change from baseline) was significantly lower during HD (P = 0.043). Blood pressure was higher during biofeedback dialysis, with significantly fewer episodes of hypotension (odds ratio, 2.0; 95% confidence interval, 1.01 to 4.4). Significantly smaller decreases in stroke volume and cardiac output and a greater increment in pulse rate were observed during biofeedback dialysis. CONCLUSION: This study shows that reversible left ventricular wall motion abnormalities develop during dialysis with ultrafiltration. We also show that this phenomenon can be ameliorated by the improved hemodynamic stability of biofeedback dialysis and therefore is a potential target for intervention.

Aged↗
PubMed2003

Analysis of patients with suspected photosensitivity referred for investigation to an Australian photodermatology clinic.

BACKGROUND: Australia's first dedicated photodermatology clinic was established at St Vincent's Hospital Melbourne in 1993. OBJECTIVE: We sought to review clinical diagnoses and results of investigations performed on patients seen at this institution. METHODS: A database was created to enable a retrospective and prospective analysis of all patients attending for evaluation of suspected photosensitivity from April 1993 to October 2000. RESULTS: A total of 513 patients were seen, 289 (56.3%) female and 224 (43.7%) male, with a mean age of 45.2 years (range: 2.6-85.9). A photosensitive disorder was diagnosed in 397 patients (77.4%), with the acquired idiopathic photodermatoses accounting for diagnoses in 215 (41.9%) of all patients seen. The most common diagnosis was polymorphous light eruption. Reduced minimal erythema doses were seen in 25.3% of all patients light tested. In those photopatch tested, 23.3% had at least 1 photocontact reaction. Allergic contact dermatitis in a photosensitive distribution was diagnosed in 7.4% of the clinic population. CONCLUSION: A large proportion of referrals to a photodermatology clinic comprise people with acquired idiopathic photodermatoses, with other common diagnoses that may mimic photosensitivity including allergic contact dermatitis, atopic dermatitis, and rosacea.

Adolescent↗
PubMed2002

Changes of photosensitivity and action spectrum with time in solar urticaria.

BACKGROUND: Solar urticaria is a rare photosensitivity disorder characterized by the rapid onset of a pruritic, erythematous and urticarial rash following sun-exposure. The action spectrum and degree of photosensitivity have been observed to change over time in several isolated reports. METHODS: Monochromator phototesting was performed on multiple occasions on 12 patients with solar urticaria. RESULTS: Six patients demonstrated normal responses in the initial phototest. They remained normal in five patients upon subsequent testing. Seven patients demonstrated abnormal immediate responses, most frequently at UVA wavelengths. Within some individuals, variations in action spectrum and/or degree of photosensitivity were observed over the years, but not over days. CONCLUSION: Significant changes in action spectrum and degree of photosensitivity may occur over years in solar urticaria. However, changes over shorter periods of time are likely to be minor and not have clinical significance.

Adolescent↗
PubMed2002

Thalidomide experience of a major Australian teaching hospital.

St Vincent's Hospital Melbourne cautiously prescribes thalidomide as a treatment for recalcitrant dermatoses. The guidelines used for prescribing and monitoring thalidomide for dermatological conditions at this institution are presented. Fourteen patients were treated with thalidomide (11 women, three men) over a 5-year period. The diagnoses of patients treated were actinic prurigo, prurigo nodularis, lupus erythematosus and Behçet's syndrome. A clinical improvement was noted in 10 patients (71.4%) prescribed thalidomide. Cessation of thalidomide treatment occurred in seven patients (50%) because of adverse effects. Of the patients with adverse effects, four developed abnormal nerve conduction studies and three developed intolerable adverse events (such as dizziness and vomiting). Adverse effects from thalidomide treatment are common but, through vigilant treatment planning, patient education and regular monitoring, the risk of permanent peripheral neuropathy and teratogenicity from thalidomide toxicity can be minimized.

Adolescent↗