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P D O'Brien

Publications and source records attributed to P D O'Brien.

8 recordsLinked to original sources
PubMed2005

The influence of pharmacological mydriasis on biomicroscopic evaluation of the glaucomatous optic nerve head.

AIMS: To investigate whether pharmacological mydriasis influences interobserver agreement or within-observer agreement (comparing estimates made before and after dilation) in the evaluation of the optic nerve head (ONH) of the glaucoma suspect or patient. METHODS: Monoscopic disc photographs of the ONH were assessed by each observer on two separate occasions in order to establish baseline intra- and inter-observer agreement. Then the ONH of 53 eyes of 53 patients was examined by each observer on two separate occasions, the pupil being pharmacologically dilated on only one of these visits. Each observer commented on the vertical and horizontal cup-to-disc (C/D) ratio, and the presence of the following ONH parameters: laminar dots; disc haemorrhage; disc saucering; disc notching, and peripapillary atrophy (PPA). RESULTS: Intersessional variability of C/D ratio estimates, based on photographs of the ONH, was similar for the two observers. The mean (+/-standard deviation) age of the 53 patients was 70 (+/-15) years, and the male : female ratio was 28 : 25. Intraobserver agreement of C/D ratio estimation performed through a dilated pupil on one occasion and an undilated pupil on the other occasion was not statistically different between observers. Interobserver agreement of C/D ratio estimates were not adversely affected in a statistically meaningful way if ONH evaluation was performed by each observer under conditions of nonmydriasis or by each observer under conditions of pharmacological mydriasis. Within-observer (before and after dilation) and interobserver agreement with respect to the presence of laminar dots (kappa=0.41-0.69), PPA (kappa=0.36-0.54), and pathological cupping (kappa=0.46-0.68) was typically moderate to good across the two visits where the pupil was dilated on one occasion only, but less reliable for saucering, disc notching and disc margin haemorrhage. CONCLUSION: Routine pharmacological mydriasis is not essential for reproducible evaluation of the ONH for patients in whom a satisfactory view of the optic disc can be achieved through the undilated pupil.

Adult↗
PubMed2001

Patient pain during different stages of phacoemulsification using topical anesthesia.

PURPOSE: To assess the pain experienced by patients during the different stages of phacoemulsification cataract surgery performed under topical anesthesia. SETTING: Ophthalmic teaching hospital, Dublin, Ireland. METHODS: This prospective study comprised 100 consecutive patients having phacoemulsification under topical anesthesia. Patients were asked to grade the pain they experienced during the different stages of the procedure using a visual analog pain scale from 0 to 10. The pain experienced during the procedure was compared with that experienced after the instillation of a drop of amethocaine. RESULTS: The overall mean pain score was 1.46. The highest mean pain score, which was during the phacoemulsification stage of the procedure, was not significantly more than the score for the administration of the topical anesthetic agent. The duration of surgery was not related to the level of pain during the procedure. CONCLUSIONS: Topical anesthesia was effective in phacoemulsification cataract surgery. Because the highest mean score was not significantly higher than that for the administration of the anesthetic agent, it is possible to counsel patients before surgery that the pain they experience during the procedure will be no worse than that during administration of the anesthetic drops.

Adult↗
PubMed1995

Relation of ultrasonic backscatter and acoustic propagation properties to myofibrillar length and myocardial thickness.

BACKGROUND: Ultrasonic backscatter demonstrates a cardiac cycle-dependent modulation. The exact mechanism of the modulation is under debate. The objective of the present study was to test the hypothesis that a change in size and configuration of myofilaments from systole to diastole alters acoustic propagation properties and backscatter. METHODS AND RESULTS: In vivo measurements were made of integrated backscatter at 5 MHz (IBR5), followed by in vitro measurements of ultrasonic attenuation, speed, and heterogeneity index using a scanning laser acoustic microscope at 100 MHz. Studies were performed in canine hearts (16) arrested in systole (8) with calcium chloride or arrested in diastole (8) with potassium chloride. Sarcomere length was measured with a calibrated eyepiece on a Ziess microscope. Wall thickness was measured with calipers. The attenuation coefficient of 220 +/- 34 dB/cm during systole was significantly higher than the coefficient of 189 +/- 24 dB/cm during diastole (P < .01); the IBR5 of -44.7 +/- 1.2 dB during systole was significantly greater than the IBR5 of -47.0 +/- 1.0 dB during diastole (P < .01); the ultrasonic speed of 1591 +/- 11 m/s during systole was higher than the speed of 1575 +/- 4.2 m/s during diastole (P < .01); and the heterogeneity index of 7.4 +/- 1.8 m/s during systole was significantly lower than the index of 9.0 +/- 2.0 m/s during diastole (P < .02). The sarcomere length of 1.804 +/- 0.142 microns during diastole was significantly higher than the length of 1.075 +/- 0.177 micron during systole (P < .01). Wall thickness was significantly greater during systole than during diastole (20 +/- 3 versus 9 +/- 3 mm, P < .01). CONCLUSIONS: Ultrasonic backscatter and propagation properties are directly related to sarcomere length and myocardial thickness and may be responsible for cardiac cycle-dependent variation in backscatter.

Animals↗
PubMed1994

Zatebradine, a specific bradycardic agent, enhances the positive inotropic actions of dobutamine in ischemic myocardium.

OBJECTIVES: This investigation determined whether attenuation of the tachycardia produced by dobutamine administration would improve perfusion and function distal to a severe coronary artery stenosis. BACKGROUND: Tachycardia adversely affects perfusion and function distal to a coronary artery stenosis. It is not known whether a specific bradycardic agent can improve blood flow and function in an ischemic zone during administration of dobutamine. METHODS: The effects of dobutamine (2, 5 and 10 micrograms/kg body weight per min) alone and in combination with zatebradine (0.5 mg/kg), a specific bradycardic agent, on hemodynamic status, segment shortening (ultrasound length transducers) and myocardial perfusion (microspheres) were studied in anesthetized dogs with severe left circumflex coronary artery stenosis. RESULTS: A 50% reduction in left circumflex coronary artery blood flow (58 +/- 4 to 29 +/- 2 ml/min [mean value +/- SEM]) produced a decrease in systolic shortening in the ischemic zone. Only a dose of dobutamine that did not elevate heart rate (2 micrograms/kg per min) produced an increase in segment shortening in the ischemic zone. High doses of dobutamine (10 micrograms/kg per min) caused an increase in heart rate without improvement in function and a reduction in the subendocardial/subepicardial flow ratio (0.74 +/- 0.06 to 0.48 +/- 0.05). Zatebradine administered in the presence of dobutamine caused a decrease in heart rate, an increase in subendocardial/subepicardial blood flow ratio (0.48 +/- 0.05 to 0.78 +/- 0.09) and allowed an increase in ischemic zone segment shortening. When normalized for changes in heart rate, ischemic zone subendocardial flow increased by 123 +/- 41% (0.39 +/- 0.09 to 0.71 +/- 0.12 ml/100 g per beat). Atrial pacing abolished the effects of zatebradine. CONCLUSIONS: The present data suggest that the perfusion-contraction matching that accompanies a decrease in heart rate results in enhancement of inotropic stimulation of an ischemic zone. The actions of zatebradine are related to an increase in subendocardial blood flow per beat that allows improvement of regional contractile function.

Animals↗
PubMedDate not supplied

Concurrent psychotropic medication has no negative influence on the outcome of electroconvulsive therapy.

A consecutive cohort of 66 subjects receiving ECT in a period of a year were studied retrospectively in order to ascertain whether concurrent psychotropic medication affected negatively their response to ECT. No correlation was found between any drug variable and any outcome variable. It is concluded that a preliminary negative result of this nature suggests that there may not be such a negative effect, but that this must be confirmed by a prospective study; it is also cautioned that, to undertake such, current ethical and legal issues may need to be resolved.

Adult↗