-
Scientific Reports Apr 2024Although the esophageal stethoscope is used for continuous auscultation during general anesthesia, few studies have investigated phonocardiographic data as a continuous...
Although the esophageal stethoscope is used for continuous auscultation during general anesthesia, few studies have investigated phonocardiographic data as a continuous hemodynamic index. In this study, we aimed to induce hemodynamic variations and clarify the relationship between the heart sounds and hemodynamic variables through an experimental animal study. Changes in the cardiac contractility and vascular resistance were induced in anesthetized pigs by administering dobutamine, esmolol, phenylephrine, and nicardipine. In addition, a decrease in cardiac output was induced by restricting the venous return by clamping the inferior vena cava (IVC). The relationship between the hemodynamic changes and changes in the heart sound indices was analyzed. Experimental data from eight pigs were analyzed. The mean values of the correlation coefficients of changes in S1 amplitude (ΔS1amp) with systolic blood pressure (ΔSBP), pulse pressure (ΔPP), and ΔdP/dt during dobutamine administration were 0.94, 0.96, and 0.96, respectively. The mean values of the correlation coefficients of ΔS1amp with ΔSBP, ΔPP, and ΔdP/dt during esmolol administration were 0.80, 0.82, and 0.86, respectively. The hemodynamic changes caused by the administration of phenylephrine and nicardipine did not correlate significantly with changes in the heart rate. The S1 amplitude of the heart sound was significantly correlated with the hemodynamic changes caused by the changes in cardiac contractility but not with the variations in the vascular resistance. Heart sounds can potentially provide a non-invasive monitoring method to differentiate the cause of hemodynamic variations.
Topics: Animals; Swine; Heart Sounds; Dobutamine; Nicardipine; Hemodynamics; Phenylephrine; Propanolamines
PubMed: 38615106
DOI: 10.1038/s41598-024-59362-3 -
Anaesthesia Apr 2020Spinal hypotension is a common and clinically important problem during caesarean section. Current consensus recommendations for resource-rich settings suggest the use of...
Prophylactic phenylephrine and fluid co-administration to reduce spinal hypotension during elective caesarean section in a resource-limited setting: a prospective alternating intervention study.
Spinal hypotension is a common and clinically important problem during caesarean section. Current consensus recommendations for resource-rich settings suggest the use of a titrated phenylephrine infusion, in combination with fluid coloading, for prevention of maternal hypotension. In resource-limited settings, where syringe drivers are unavailable, these recommendations advise the addition of 500 μg phenylephrine to the first 1 l of intravenous fluid given after initiation of spinal anaesthesia, with additional vasopressor boluses as required. This prospective, alternating intervention study compared the use of a conventional phenylephrine rescue bolus strategy for prevention of hypotension, defined as systolic arterial pressure < 90 mmHg, with a phenylephrine infusion given according to the consensus recommendation. We studied 300 women having elective caesarean section. There were 77 (51%) women who developed hypotension in the bolus group vs. 55 (37%) in the phenylephrine infusion group (p = 0.011). This represented a 29% reduction in hypotension, with a number needed to treat of 6.8. The six highest systolic arterial pressure readings occurred in the phenylephrine infusion group (range 166-188 mmHg), and there were four instances of bradycardia (heart rate < 50 beats.min ) with preserved systolic arterial pressure in each group. There were no adverse clinical sequelae, and no differences in neonatal Apgar scores in either group. The consensus recommendation for phenylephrine and fluid co-administration in resource-limited settings appears effective in preventing maternal hypotension, but at the cost of sporadic systolic hypertension.
Topics: Adult; Cesarean Section; Combined Modality Therapy; Developing Countries; Elective Surgical Procedures; Female; Fluid Therapy; Health Resources; Humans; Hypotension; Infusions, Intravenous; Phenylephrine; Prospective Studies; South Africa; Treatment Outcome; Vasoconstrictor Agents
PubMed: 31811659
DOI: 10.1111/anae.14950 -
The British Journal of Ophthalmology Oct 1970
Topics: Adrenergic alpha-Antagonists; Humans; Hydroquinones; Miotics; Mydriatics; Phenylephrine; Pupil
PubMed: 4394336
DOI: 10.1136/bjo.54.10.690 -
Journal of Cataract and Refractive... Feb 2024Phenylephrine, a potent sympathomimetic, induces mydriasis via iris dilator muscle contraction. Intracameral (IC) phenylephrine has been successfully used in cataract...
Phenylephrine, a potent sympathomimetic, induces mydriasis via iris dilator muscle contraction. Intracameral (IC) phenylephrine has been successfully used in cataract surgery for initial mydriasis, maintaining mydriasis, and management of intraoperative floppy-iris syndrome. Serious systemic adverse events (mainly cardiovascular) have been described with topical phenylephrine drops, but we found very little evidence of such adverse events associated with IC phenylephrine use. However, we suspect under-reporting of such adverse events, as they may instead be ascribed to anxiety, positioning, anesthesia, etc. Optimal dosage/concentrations for IC phenylephrine use in different purposes have not been fully studied. In the absence of robust evidence, we suggest that lower but effective IC phenylephrine concentrations are used: a lower concentration (0.31%), in conjunction with an anticholinergic and lidocaine, may be used for initial mydriasis. For management of intraoperative floppy-iris syndrome, 0.31% may be effective, though a higher concentration (1% to 1.25%) may be required.
Topics: Humans; Phenylephrine; Mydriasis; Mydriatics; Phacoemulsification; Iris Diseases; Iris; Intraoperative Complications; Iatrogenic Disease; Pupil
PubMed: 37748029
DOI: 10.1097/j.jcrs.0000000000001319 -
Arquivos Brasileiros de Oftalmologia 2022To evaluate the effect of pupil dilation on intraocular pressure in preterm and term newborns.
PURPOSE
To evaluate the effect of pupil dilation on intraocular pressure in preterm and term newborns.
METHODS
This prospective study involved 55 eyes of 28 preterm infants and 38 eyes of 20 term infants. The infants were divided into two groups according to their gestational ages at birth as follows: preterm group, <37 weeks and term group, ≥37 weeks. Pupil dilation was attained with tropicamide 0.5% and phenylephrine 2.5%. Intraocular pressure measurements were performed with Icare PRO (Icare Finland Oy, Helsinki, Finland) before and after pupil dilation. A paired t test was used to compare the measurements before and after pupil dilation.
RESULTS
The mean intraocular pressure change was -1.04 ± 3.03 mmHg (6.20/-11.40 mmHg) in the preterm group and -0.39 ± 2.81 mmHg (4.60/-9.70 mmHg) in the term group. A statistically significant difference in intraocular pressure was observed only in the preterm group after pupil dilation (p=0.01).
CONCLUSION
An unexpected alteration in intraocular pressure in newborns may occur after pupil dilation, especially in preterm infants.
Topics: Humans; Infant, Newborn; Infant, Premature; Intraocular Pressure; Mydriatics; Phenylephrine; Prospective Studies; Pupil; Tropicamide
PubMed: 34852054
DOI: 10.5935/0004-2749.20220058 -
Medical Science Monitor : International... Feb 2019BACKGROUND This study aimed to compare the efficacy and safety of bolus norepinephrine, phenylephrine, and ephedrine in parturient with preeclampsia who had hypotension... (Comparative Study)
Comparative Study
A Comparative Study of Bolus Norepinephrine, Phenylephrine, and Ephedrine for the Treatment of Maternal Hypotension in Parturients with Preeclampsia During Cesarean Delivery Under Spinal Anesthesia.
BACKGROUND This study aimed to compare the efficacy and safety of bolus norepinephrine, phenylephrine, and ephedrine in parturient with preeclampsia who had hypotension during cesarean delivery under spinal anesthesia. MATERIAL AND METHODS One hundred and sixty-six parturient women with preeclampsia who had a baseline systolic blood pressure (SBP) <80% during spinal anesthesia for cesarean section were divided into three treatment groups; bolus norepinephrine 4 μg (group N) (n=56), phenylephrine 50 μg (group P) (n=55), and ephedrine 4 mg (group E) (n=55). Primary outcomes included overall SBP and heart rate (HR) until delivery. Secondary outcomes included the incidence of tachycardia (HR >120 bpm), bradycardia (HR <60 bpm), hypertension (SBP >120% baseline), number of boluses of vasopressor required and episodes of hypotension, maternal side effects, and neonatal outcome. RESULTS Overall HR in group N was significantly increased compared with group P (80.5±12 vs. 76.6±6.9 bpm; P=0.04), and significantly lower compared with group E (80.5±12 vs. 84.9±7.1 bpm; P=0.02). Parturients in group N had fewer episodes of bradycardia compared with group P (3.6% vs. 21.8%; RR=0.26l; 95% CI, 0.07-0.73; P=0.004) and fewer episodes of tachycardia compared with group E (16.1% vs. 36.4%; RR 0.54; 95% CI, 0.29-0.90; P=0.02). CONCLUSIONS A bolus dose of norepinephrine showed similar efficacy to phenylephrine but improved maternal and neonatal safety in parturients with preeclampsia with hypotension during cesarean section under spinal anesthesia.
Topics: Adult; Anesthesia, Spinal; Blood Pressure; Cesarean Section; China; Ephedrine; Female; Heart Rate; Humans; Hypotension; Norepinephrine; Parturition; Phenylephrine; Pre-Eclampsia; Pregnancy; Pregnancy Complications; Treatment Outcome; Vasoconstrictor Agents
PubMed: 30738019
DOI: 10.12659/MSM.914143 -
Circulation Journal : Official Journal... Feb 2018The gastroepiploic artery (GEA) plays an important role in the era of multiple arterial revascularization, but spasm is a major matter of concern. The internal thoracic...
BACKGROUND
The gastroepiploic artery (GEA) plays an important role in the era of multiple arterial revascularization, but spasm is a major matter of concern. The internal thoracic artery has been shown to have a strong tendency to spasm in its distal bifurcating part, whereas the segmental difference in vasoreactivity of the GEA has never been performed.Methods and Results:The full length of the GEA obtained from 21 patients undergoing a total gastrectomy was divided into 3 sections: proximal (5 cm from the origin), middle, and distal (5 cm from the end). Concentration-response curves for vasoconstrictors (phenylephrine, prostaglandin F2α, and endothelin-1) and vasodilators (carperitide, nitroglycerin, and nifedipine) were then established using organ baths. All the vasoconstrictors and vasodilators produced concentration-dependent responses in each section. As the concentration of the vasoconstrictors increased, segments at the distal section showed a significantly greater contraction than those at the middle and proximal sections regardless of the type of vasoconstrictor. The effective concentration of drugs that caused 50% of the maximal response for endothelin-1 was significantly greater in the distal section than that in the proximal sections. No significant difference was found in vasodilators-induced relaxation.
CONCLUSIONS
The contractility increases toward to the end of the GEA. Clinically, the distal portion of the GEA should be trimmed off and not be used as an anastomotic site wherever possible.
Topics: Dinoprost; Dose-Response Relationship, Drug; Endothelin-1; Gastroepiploic Artery; Humans; Phenylephrine; Vasoconstriction; Vasoconstrictor Agents
PubMed: 29238009
DOI: 10.1253/circj.CJ-17-0943 -
Anaesthesia May 2017Prophylactic vasopressor administration is commonly recommended to reduce maternal hypotension during spinal anaesthesia for caesarean section. Metaraminol has undergone... (Randomized Controlled Trial)
Randomized Controlled Trial
A randomised double-blind trial of phenylephrine and metaraminol infusions for prevention of hypotension during spinal and combined spinal-epidural anaesthesia for elective caesarean section.
Prophylactic vasopressor administration is commonly recommended to reduce maternal hypotension during spinal anaesthesia for caesarean section. Metaraminol has undergone limited investigation in obstetric anaesthesia for this purpose, particularly in comparison with phenylephrine. In this multicentre, randomised, double-blind, non-inferiority study, we compared prophylactic phenylephrine or metaraminol infusions, started immediately after spinal anaesthesia, in 185 women who underwent elective caesarean section. Phenylephrine was initially infused at 50 μg.min , and metaraminol at 250 μg.min . The primary outcome was the difference in umbilical arterial pH between groups; secondary outcomes included other neonatal acid-base measures, and maternal haemodynamic changes. The mean (SD) umbilical arterial pH was 7.28 (0.06) in the phenylephrine group vs. 7.31 (0.04) in the metaraminol group (p = 0.0002). The estimated mean (95%CI) pH difference of 0.03 (0.01-0.04) was above the pre-determined lower boundary of clinical non-inferiority, and also met the criterion for superiority. Umbilical artery lactate concentration was 2.8 (1.2) mmol.l in the phenylephrine group vs. 2.3 (0.7) mmol.l in the metaraminol group (p = 0.0018). Apgar scores did not significantly differ between groups. There was a higher incidence of hypotension, defined as systolic arterial pressure < 90% baseline, in the phenylephrine group; there was a higher incidence of hypertension and severe hypertension (systolic arterial pressure > 110% and > 120% baseline, respectively) in the metaraminol group. There was no significant difference between groups in the incidence of nausea, vomiting or maternal bradycardia. We conclude that, when used as an infusion to prevent hypotension after spinal anaesthesia for elective caesarean section, metaraminol is at least non-inferior to phenylephrine with respect to neonatal acid-base outcomes.
Topics: Acid-Base Equilibrium; Adult; Anesthesia, Epidural; Anesthesia, Obstetrical; Anesthesia, Spinal; Cesarean Section; Double-Blind Method; Elective Surgical Procedures; Female; Humans; Hypotension; Infant, Newborn; Infusions, Intravenous; Lactic Acid; Metaraminol; Phenylephrine; Postoperative Nausea and Vomiting; Pregnancy; Treatment Outcome; Vasoconstrictor Agents; Young Adult
PubMed: 28255987
DOI: 10.1111/anae.13836 -
Scientific Reports Jan 2023An optimization approach based on full factorial design was employed for developing an HPLC-UV method for simultaneous determination of a quaternary mixture used for the...
An optimization approach based on full factorial design was employed for developing an HPLC-UV method for simultaneous determination of a quaternary mixture used for the treatment of symptoms related to common cold and COVID-19. The quaternary mixture is composed of paracetamol, levocetirizine dihydrochloride, phenylephrine hydrochloride and ambroxol hydrochloride. The developed technique is a green, fast and simple method that uses isocratic elution of mobile phase consisting of 20:5:75 (v/v) of ethanol: acetonitrile: 2.5 mM heptane-1-sulphonic acid sodium salt at pH 6.5 [Formula: see text] 0.02. The chromatographic separation was carried out using Hypersil BDS Cyano LC Column (250 × 4.6 mm, 5 μm) with 230 nm UV detection and 1.0 mL/min. flow rate. Avoiding the routine methodology and resorting to the modern technology-represented in the usage of experimental design-allows rapid determination of the four drugs using the optimum quantity of chemicals to avoid any waste of resources. The quaternary mixture was eluted in less than 9 min., where retention times of paracetamol, levocetirizine dihydrochloride, phenylephrine hydrochloride and ambroxol hydrochloride were found to be 2.2, 3.8, 6.6 and 8.8 min., respectively. The calibration graphs of the four drugs were linear over concentration ranges of 50.0-500.0, 0.5-20.0, 0.5-20.0 and 0.5-100.0 µg/mL for paracetamol, levocetirizine dihydrochloride, phenylephrine hydrochloride and ambroxol hydrochloride, respectively with correlation coefficients higher than 0.999. The method is accurate with mean recoveries between 99.87 and 100.04%, precise, as %RSD for the intraday and interday precision were between 0.61 and 1.64% and very sensitive with limit of detections (LOD)'s between 29 and 147 ng/mL and limit of quantification (LOQ)'s between 95 and 485 ng/mL. The proposed method was successfully applied for the analysis of the four drugs either in raw materials or in prepared tablet with the least amount of chemicals within short time. It is also validated following International Conference on Harmonization Guidelines. The proposed method was found to be green according to the most common greenness assessment tools; NEMI, GAPI, Analytical Eco-Scale and AGREE methods. The advantages of the proposed method qualify it for routine analysis of the studied drugs either in single or co-formulated dosage form in quality control labs.
Topics: Humans; Ambroxol; Common Cold; Chromatography, High Pressure Liquid; Acetaminophen; COVID-19; Phenylephrine
PubMed: 36709387
DOI: 10.1038/s41598-023-28737-3 -
Vascular Pharmacology Aug 2023Sympathomimetic amines, including β-phenylethylamine (PEA), constrict animal blood vessels but their mechanism of action is not now thought to be through...
Sympathomimetic amines, including β-phenylethylamine (PEA), constrict animal blood vessels but their mechanism of action is not now thought to be through α-adrenoceptors and release of noradrenaline but via trace amine-associated receptors (TAARs). This information is not available for human blood vessels. Functional studies were therefore performed on human arteries and veins to establish whether they constrict to PEA and whether any constrictions are adrenoceptor-mediated. Isolated internal mammary artery or saphenous vein rings were set up in Kreb's-bicarbonate solution at 37 ± 0.5 °C gassed with O:CO (95:5) under class 2 containment. Isometric contractions were measured and cumulative concentration-response curves for PEA or the α-adrenoceptor agonist, phenylephrine were established. PEA showed concentration-related contractions. The maximum was significantly greater in arteries (1.53 ± 0.31 g, n = 9) than veins (0.55 ± 0.18 g, n = 10), but not when plotted as % of KCl contractions. PEA showed slowly developing contractions plateauing at 17,3 ± 3.7 min in mammary artery. The reference α-adrenoceptor agonist, phenylephrine, exhibited more rapid onset (peak 5.0 ± 1.2 min) but non-sustained contractions. In saphenous veins, PEA (62.8 ± 10.7%) and phenylephrine (61.4 ± 9.7%, n = 4) displayed the same maximum, but phenylephrine was more potent. The α-adrenoceptor antagonist, prazosin (1 μM), blocked phenylephrine contractions of mammary arteries but not PEA contractions in either vessel. PEA causes substantial vasoconstriction of human saphenous vein and mammary artery, which explains its vasopressor actions. This response, however, was not mediated via α-adrenoceptors, but likely due to TAARs. The classification of PEA as a sympathomimetic amine on human blood vessels is therefore no longer valid and requires revision.
Topics: Animals; Humans; Mammary Arteries; Vasoconstriction; Saphenous Vein; Phenylephrine; Norepinephrine; Receptors, Adrenergic
PubMed: 37399882
DOI: 10.1016/j.vph.2023.107191