Background: Induction of anaesthesia with propofol is often associated with a significant decrease in arterial pressure, especially in the older population. The aim of this study is to determine the efficacy of phenylephrine in two different doses i.e. 100mcg and 200mcg, given during induction to counteract the anticipated hypotensive effect of propofol in older patients aged over 55 years. Methods: Seventy-two ASA physical status I – II patients aged 55 years or older were randomly allocated to group 1 (received propofol mixed with normal saline), group 2 (propofol mixed with 100mcg of phenylephrine) or group 3 (propofol mixed with 200mcg of pheynylphrine). Anaesthesia was induced with fentanyl 1.5mcg/kg and propofol 2mg/kg (mixed with the study drug). Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP) and heart rate (HR) were recorded at 1 minute intervals for up to 5 minutes after induction. Results: SBP, MAP and DBP decreased significantly after induction in the control group and group 2 (phenylephrine 100mcg). In contrast, SBP was maintained to near baseline for the first two minutes after induction using phenylephrine 200mcg in group 3, and similar trends were seen with MAP and DBP at a lesser magnitude. Conclusion: Phenylephrine 200mcg is more effective than 100mcg in attenuating propofol induced hypotension, especially during the first two minutes after induction, in patients aged 55 years and above.
Phenylephrine ; Propofol

No abstract available.
Phenylephrine* ; Receptors, Cholinergic* ; Vas Deferens*

In order to evaluate the effect of topical dapiprazole, an alpha-adrenergic receptor blocker, in reversing mydrisis by 1% tropicamide and 2.5% phenylephrine, we studied 89 subjects. 0.5% dapiprazole in one eye of each subject after full dilatation of both pupils. The pupillary diameter was calibrated, and thereafter statistical analysis was performed with student paired t-test. Thirty minutes after instillation of dapiprazole, there was a highly significant difference of the decreasing rate in pupil size between the dapiprazole treated eyes and the control eyes(p<0.001). The time for complete reversal of mydriasis was also at least 4 hours shorter in the dapiprazole treated eyes than the control eyes(p<0.006). This study suggests that 0.5% dapiprazole is effective in reversing mydriasis caused by 1% tropicamide and 2.5% phenylephrine, and also effective in making the eyes comfortable in a shorter time.
Dilatation ; Humans ; Mydriasis* ; Phenylephrine* ; Pupil ; Tropicamide

To predict the mydriatic status of the cataract patients preoperatively, we performed maximal mydriasis test with stepwise instillations of 1% tropicamide and 2.5% phenylephrine or 10% phenylephrine to the out-patients who was scheduled to have cataract operation. Among 210 eyes of 113 patients, the pupillary size of 167 eyes was dilated to 8mm or more and the other 43 eyes were insufficiently dilated to less than 8mm diameter. In the insufficiently dilated group, we have observed the presumable causes of insufficient mydriasis as follows: posterior synechiae, diabetic autonomic pupillopathy, age-related miosis and unknown. By this test, we could predict the mydriatic status of the cataract patient preoperatively and could prepare the appropriate operative method and equipment effectively.
Cataract* ; Humans ; Miosis ; Mydriasis* ; Outpatients ; Phenylephrine ; Tropicamide

Phenylephrine hydrochloride has been widely used in ocular theraphy and examination, such as the treatment of uveitis and glaucoma and examination of the eye ground. In this study, mydriatic action of single instillation of 10% phenylephrine hydrochloride solution was compared with that of combined instillation of 10% phenylephrine hydrochloride solution and 0.5% tetracaine drops in 110 brown eyes. The following results were obtained; 1) In 55 eyes, the diameter of the pupil reached more than 7 mm about 45 minutes after instillation of 10% phenylephrine hydrochloride solution. 2) In case of combined instillation of 0.5% tetracaine solution and 10% phenylephrine hydrochloride solution, the onset of mydriasis was delayed. 3) In the case of combined instillation of 0.5% tetracaine and 10% phenylephrine hydrochloride solution with 5 and 10 minutes interval, the action of mydriasis was acceralated. 4) After tonometry, the action of mydriasis was more acceralated.
Glaucoma ; Manometry ; Mydriasis ; Phenylephrine* ; Pupil ; Tetracaine ; Uveitis

Topical phenylephrine is used in nasotracheal intubation to prevent nasal mucosal bleeding. The administration of topical phenylephrine can result in severe hypertension secondary to alpha-adrenergic stimulation. A high incidence of pulmonary edema is present in the patients given drugs with beta-blocking activity after phenylephrine administration. We report upon a pediatric patient in whom severe hypertension and pulmonary edema occured following the administration of topical phenylephrine.
Anesthesia, General* ; Hemorrhage ; Humans ; Hypertension ; Incidence ; Intubation ; Phenylephrine* ; Pulmonary Edema*

PURPOSE: This study was aimed at investigating the role of betaadrenoceptor subtypes in mediating the relaxation and contraction of seminal vesicles in rabbits. MATERIALS AND METHODS: Relaxation or contractile responses of epithelium- removed muscle strips of a rabbit seminal vesicle, which were precontracted with 10-5M norepinephrine, to selective betasubtypes-adrenoceptor agonists were observed in an organ bath. The contractile responses induced by isoproterenol were also observed after application of selective antagonists. RESULTS: Isoproterenol showed a concentration-dependent contractile response, but the contractility was weaker than those with phenylephrine and norepinephrine. The betaselective-agonists(xamoterol for beta, clenbuterol for beta and BRL37344 for beta) alone evoked neither contraction nor relaxation. However, the beta- and beta-agonists inhibited the contraction of the precontracted strips with 10-5M norepinephrine, while the beta-agonist enhanced the contraction. The pretreatment with a beta-antagonist(ICI118551) reduced the tension of the strips developed by 10-4M isoproterenol, but the beta-(atenolol) and beta-(SR59230A) antagonists showed no changes in the response. CONCLUSIONS: beta- and beta-adrenoceptors seem to mediate the relaxation of the seminal vesicle, while the beta-adrenoceptor may have a supplementary role in contraction.
Baths ; Clenbuterol ; Isoproterenol ; Negotiating ; Norepinephrine ; Phenylephrine ; Rabbits ; Relaxation* ; Seminal Vesicles*

We assessed the combined effects of dapiprazole, an alpha-adrenergic receptor blocker, with pilocarpine. direct-acting parasympathomimetics, on reversing mydriasis and cycloplegia in 40 eyes (20 subjects) who received 1% tropicamide or 2.5% phenylephrine for pupillary dilation and cycloplegic refraction. These results were compared to 40 eyes (20 subjects) that received dapiprazole alone. The study was divided into four groups, each of which consisted of 20 eyes that received either 1% tropicamide or 0.5% phenylephrine followed by instillation of 0.5% dapiprazole alone or in combination with 2% pilocarpine. A significant difference in the reduction of pupil size and the increase in accommodative amplitude has been observed between the groups that received dapiprazole alone and those received both dapiprazole and pilocarpine(p<0.001). These results suggest that dapiprazole and pilocarpine eyedrops have additive effects on reversing both mydriasis and cycloplegia after instillation of 1% tropicamide or 2.5% phenylephrine for pupillary dilation and cycloplegic refraction.
Mydriasis* ; Ophthalmic Solutions ; Parasympathomimetics ; Phenylephrine ; Pilocarpine* ; Pupil ; Tropicamide

Graded infusion and bolus injection methods of vasoactive drugs have both been used to measure baroreflex sensitivity. To determine whether the two methods produce the same values of baroreceptor sensitivity, phenylephrine and nitroglycerin was administered intravenously by both graded infusion and bolus injection methods to 11 rabbits. To evaluate the baroreflex control of heart rate(HR), a logistic sigmoid function model was used. The range of HR and baroreflex gain by the bolus method(100.53+/-0.62, 0.113+/-0.011) were significantly(p<0.05) larger than those measured by the graded infusion method(108.49+/-1.66, 0.126+/-0.013). However, there were no significant changes in the pressure at the midrange of the baroreflex curve. Thus my results indicate that baroreflex control of HR by the graded infusion and bolus injection methods is not equivalent and that baroreflex-induced HR response to a gradual change in pressure is less than that seen with a repid change.
Baroreflex* ; Colon, Sigmoid ; Heart ; Heart Rate ; Nitroglycerin ; Phenylephrine ; Pressoreceptors ; Rabbits*

BACKGROUND: The sequence method of determining baroreflex sensitivity (BRSSEQ) has been reported to correlate poorly with the phenylephrine method of determining BRS in individuals with attenuated BRS. Inhalation anesthetics are also known to decrease BRS. We therefore assessed the effect of varying the systolic blood pressure (SBP) and R-R interval (RRI) thresholds on BRSSEQ values and compared these results with the BRS obtained by the modified Oxford technique (BRSMODOX). METHODS: The average number of valid sequences and BRSSEQ values were derived by varying the SBP threshold from 0.5 to 2.5 mmHg and the RRI threshold from 1 to 6 ms, and the relation of BRSSEQ values to BRSMODOX values using sequential administration of nitroprusside and phenylephrine was assessed in 40 healthy individuals during sevoflurane anesthesia. RESULTS: Increasing either the SBP thresholds or RRI thresholds resulted in a decrease in the number of valid sequences. As the SBP thresholds were decreased and the RRI thresholds were increased, BRSSEQ values increased. When the SBP threshold exceeded 1 mmHg, no significant correlations were observed between BRSSEQ and BRSMODOX values. Significant correlations between the two methods were observed for an SBP threshold of 0.5 mmHg and RRI thresholds of 1, 2, 3 and 4 ms. Biases between the two methods were 2.1, 2.1, 0.4, and 0.4 ms/mmHg for 0.5 mmHg and 1, 2, 3 and 4 ms. CONCLUSIONS: These findings suggest that adjusting the SBP threshold to 0.5 mmHg and the RRI threshold to 3 or 4 ms may improve BRSSEQ validity during sevoflurane anesthesia, when compared to BRSMODOX.
Anesthesia* ; Anesthetics, Inhalation ; Baroreflex* ; Bias (Epidemiology) ; Blood Pressure* ; Nitroprusside ; Phenylephrine