Dose equivalence between metaraminol and norepinephrine in critical care.

AIMS: The aim of this study was to determine the conversion dose ratio between continuous infusion metaraminol and norepinephrine in critically ill patients with shock. METHODS: A retrospective cohort study was conducted in adult patients with shock admitted to an intensive care unit from 29 October 2018 to 30 October 2019 and who transitioned from metaraminol monotherapy to norepinephrine monotherapy. Mean arterial pressure (MAP) and infusion doses for both drugs were collected at hourly intervals; 2 hours before to 5 hours after switching from metaraminol monotherapy to norepinephrine monotherapy. The conversion dose ratio was defined as the ratio of metaraminol (µg.kg-1 .min-1) : norepinephrine (µg.kg-1 .min-1 ) required to achieve a similar MAP. RESULTS: A total of 43 out of 144 eligible patients were included. The median age was 68 years (IQR 56-76) and 22 (51%) were male. There was no significant difference between the baseline MAP during metaraminol monotherapy (median 71 mm Hg, IQR 66-76) and the post-transition MAP during norepinephrine monotherapy (median 70 mm Hg, IQR 66-73) (P = .09). The median conversion dose ratio between metaraminol and norepinephrine was 13 (IQR 7-24). In the sensitivity analyses, the median conversion dose ratio using the maximum and the mean norepinephrine infusion dose was 8 (IQR 5-16) and 12 (IQR 8-23), respectively. CONCLUSION: A conversion dose ratio of 10:1 (metaraminol µg.kg-1 .min-1 :norepinephrine µg.kg-1 .min-1 ) may be used in critically ill patients with shock to account for ease of calculations and variability of the conversion ratio in the primary and sensitivity analyses.

Predrawn prehospital medications are microbiologically safe for up to 48 hours.

BACKGROUND: Prehospital medical teams are commonly required to administer a range of medications for urgent stabilisation and treatment. The safe preparation of medications during resuscitation requires attention, time and resources, and can be a source of medication error. In our two road and HEMS (Helicopter Emergency Medical Service) prehospital services, medication errors are mitigated by predrawing commonly used medications to set concentrations daily (Hunter Retrieval Service, HRS) or second-daily (CareFlight Sydney, CFS). However, there are no published data confirming that such practice is microbiologically safe. METHODS: A convenience sample of 299 predrawn medication syringes with syringe dwell times up to 48 hours were collected at the end of their operational deployment. Predrawn medication syringes collected for culture were ketamine, midazolam, fentanyl, thiopentone, rocuronium, suxamethonium, metaraminol and normal saline. The samples were incubated and cultured at a tertiary hospital pathology laboratory using best-practice methodology for non-tissue samples. The samples were collected from June 2017 to February 2018. RESULTS: The mean dwell times ranged from 30.7 hours (fentanyl at HRS) to 48.5 hours (rocuronium at CFS). None of the 299 cultured samples yielded significant micro-organisms. One sample of suxamethonium with a syringe dwell time of 34 hours grew Bacillus cereus but was likely a contaminant introduced during sample collection. CONCLUSION: Predrawing of the eight studied medications for urgent prehospital procedures appears to be a microbiologically safe practice with syringe dwell times up to 48 hours.

The use of vasopressors during spinal anaesthesia for caesarean section.

PURPOSE OF REVIEW: Hypotension remains one of the most researched subjects in obstetric anaesthesia. The purpose of this study is to review the most recent published articles on the use of vasopressors during spinal anaesthesia for caesarean section. RECENT FINDINGS: Despite continued research indicating advantages of phenylephrine over ephedrine, practitioners in some countries continue to favour ephedrine. Recent research has continued to compare the two drugs with some work emerging on high-risk patients. Concern about reflexive bradycardia during phenylephrine use has led to consideration of alternatives. Norepinephrine which has mild ß-adrenergic activity has been shown to have equivalent pressor activity but with less depressant effect on heart rate and cardiac output versus phenylephrine. Research continues to focus on methods of vasopressor administration. Prophylactic infusions of phenylephrine have been shown to be effective and may require less physician intervention compared with intermittent boluses. Automated computer-controlled systems have been further investigated using multiple agents and continuous noninvasive blood pressure monitoring. SUMMARY: Evidence continues to support phenylephrine as the first-line vasopressor in obstetrics. However, recent research is emerging to suggest that low-dose norepinephrine may be a better alternative. Prophylactic infusions are effective and automated systems have potential for the future.

Myocardial infarction associated with the administration of intravenous ephedrine and metaraminol for spinal-induced hypotension.

A 31-year-old female with no risk factors for cardiac disease suffered a peri-operative myocardial infarction during an elective gynaecological procedure under spinal anaesthesia. The timing and nature of cardiac symptoms suggest that the myocardial infarction was caused by coronary artery vasospasm secondary to ephedrine and/or metaraminol, which were administered to treat spinal-induced hypotension. We review the recent literature and case reports on myocardial infarction attributed to sympathomimetic drugs, and recommend the use of sublingual or intravenous nitrates when signs or symptoms of coronary arterial vasospasm become evident during their use.

Effect of dopamine and metaraminol on the renal function of patients with septic shock.

BACKGROUND: Vasoactive drugs are often necessary for reversing hypotension in patients with severe infection. The standard for evaluating effects of vasoactive drugs should not only be based on the increase of arterial blood pressure, but also on the blood flow perfusion of internal organs. The effects of dopamine and metaraminol on the renal function of the patients with septic shock were investigated retrospectively in this study. METHODS: Ninety-eight patients with septic shock were divided into three groups according to the highest infusing rate of metaraminol, with the lightest infusing rate of (0.1 - 0.5, 0.6 - 1.0, > 1.0) microgxkg(-1)xmin(-1) in group A, B and C respectively. Urine output, mean arterial blood pressure (MAP), heart rate (HR), urine output, blood urea nitrogen (BUN), creatinine (CRE), urine albumin (U-ALB), urine beta(2)-microglubulin (Ubeta(2)-MG) and Apache III scores were recorded. RESULTS: Before antishock therapy, hypotension, tachycardia and oliguria occurred to all the 98 patients with septic shock and CRE, BUN, U-ALB, Ubeta(2)-MG and Apache III scoring were abnormal in most cases. With the antishock therapy, MAP, HR, urine output, BUN and CRE in all patients returned gradually to normal (P < 0.05 or < 0.01 compared to those before antishock therapy). U-ALB, Ubeta(2)-MG output and Apache III scoring also reverted but remained abnormal (P < 0.01 compared to those before antishock therapy). No statistically significant differences in the changes of these indices with the time existed among the three groups (P > 0.05). CONCLUSION: Dopamine and metaraminol when applied to the patients with septic shock could effectively maintain the circulatory stability and promote restoration of renal function.

Effect of metaraminol during acute inferior wall myocardial infarction accompanied by hypotension: preliminary study.

This study was designed to evaluate the effects of metaraminol (Aramine) in six patients with evolving acute inferior wall myocardial infarction accompanied by hypotension and warm limbs. There were 16 episodes of acute inferior wall ischemia, and the response to therapy was judged by evaluating blood pressure and ST segment and T wave abnormalities. Three patients received intravenous isosorbide dinitrate and two received streptokinase as the initial therapy. The mean ST segment elevation was significantly reduced (from 4.94 +/- 1 to 0.5 +/- 0.7 [p less than 0.0001]) after metaraminol infusion was initiated. The average T wave height also decreased (from 6.8 +/- 2 to -1.3 +/- 2.5 mm [p less than 0.0005]). The average heart rate decreased from 82 +/- 11 to 69 +/- 9 beats/min (p less than 0.05) and the mean arterial blood pressure increased from 81 +/- 12 mm Hg before metaraminol treatment to 126 +/- 8 mm Hg after treatment. All these changes occurred within a few minutes after metaraminol therapy was instituted. In 12 episodes, accelerated idioventricular rhythm appeared concomitantly with the resolution of ST segment elevation. Coronary angiography performed between 4 and 10 days after admission demonstrated significant obstruction in all infarct-related arteries, but none was totally occluded. Left ventricular function was normal in three patients and slightly hypokinetic in the inferior wall in two. These results indicate that in a selected group of patients with acute inferior myocardial infarction, metaraminol administration (in certain hemodynamic circumstances) can alleviate acute ischemia within a few minutes and thereby reduce ischemic injury.

Metaraminol (Aramine) in the management of a significant amlodipine overdose.

OBJECTIVE: To report a patient with a significant amlodipine self-poisoning who failed to clinically respond to conventional treatment and was managed with metaraminol (Aramine). PATIENT: A 43-year old male presenting after ingestion of 560 mg amlodipine, who failed to respond clinically to treatment with fluid resuscitation, calcium salts, glucagon and norepinephrine/epinephrine inotropic support. MAIN RESULTS: Following a loading bolus of 2 mg and intravenous infusion (83 microg/min) of metaraminol (Aramine) there was improvement in his blood pressure, cardiac output and urine output. CONCLUSIONS: This is the first case report of the beneficial use of metaraminol (aramine) in the management of significant amlodipine poisoning unresponsive to conventional therapy.

Is paraplegia after repair of coarctation of the aorta due principally to distal hypotension during aortic cross-clamping?

The hypothesis is presented that paraplegia after coarctation of the aorta is principally due to hypotension of sufficient severity and duration. In a group of 103 patients who underwent surgery during a 10-year period, the distal aortic pressure was maintained above 60 mm Hg while the aorta was cross-clamped or the period of cross-clamping was limited to less than 20 minutes. No neurologic problems occurred. In 17 of the 103 cases aortic pressure decreased below 60 mm Hg, occurring in 8% of patients with the aorta occluded below the left subclavian artery but in 30% of those occluded above. Therapeutic measures used in the 17 patients included infusion of metaraminol in five and limiting cross-clamp time to less than 20 minutes in 11. The theory is proposed that ligation of intercostal arteries in a patient with coarctation cannot injure the spinal cord because the normal direction of blood flow is reversed. Certainly, in patients without a coarctation, such as thoracic aneurysms, ligation of a critical intercostal artery may injure the spinal cord. However, in patients with coarctation the direction of blood flow is reversed, blood flowing from the intercostals into the distal aorta. The vague relationship long noted between development of collateral circulation, including rib notching, and the frequency of paraplegia probably depends not on the presence of enlarged intercostal arteries but on whether their temporary occlusion at the time of aortic cross-clamping results in distal hypotension. Data with somatosensory-evoked potentials measured during operations on the thoracic aorta in 25 patients found no changes in sensory potentials as long as the distal aortic pressure remained above 60 mm Hg, but a gradual disappearance was found at lower pressures. In five of six patients with large thoracicoabdominal aneurysms in whom sensory potentials were absent for longer than 30 minutes, paraplegia resulted. Use of somatosensory potentials provides a significant method for evaluating methods to protect from paraplegia. This method should be far more productive than are simple clinical experiences because the fortunate rare occurrence of paraplegia, one in 200, greatly limits available data.

The incidence and management of priapism in Western Australia: a 16 year audit.

The objective of the study was to conduct a retrospective audit of patients who presented with priapism in Western Australia during the years 1985-2000. We searched the records of the teaching hospitals in metropolitan Perth and those of the Keogh Institute for Medical Research for the diagnostic code for priapism. A total of 82 episodes of priapism in 63 patients occurred over this 16 year period. In all, 62 episodes occurred after intracavernosal injections (ICI) and 20 were due to other causes. Treatment of priapism included simple aspiration of blood, intracavernosal injection of alpha-adrenergic agents and surgical shunt procedures. Priapism occurring outside the setting of ICI was more likely to require surgery; seven of 20 episodes. After ICI therapy, eight of 62 episodes required shunts. The use of prostaglandin E1 as the drug of choice in ICI therapy in 1989 led to a fall in the incidence of ICI-induced priapism. Priapism is a major side effect of ICI therapy and an uncommon, although important, side effect of other conditions. The incidence of priapism has fallen with the introduction of prostaglandin E1 monotherapy as the favoured drug for ICI therapy of erectile failure.

Metaraminol and dobutamine for the treatment of hypotension associated with epidural block.

In 14 patients undergoing major abdominal surgery, epidural analgesia was performed and cardiovascular changes were examined by insertion of Swan-Ganz catheters. To counteract the hypotensive episodes associated with epidural block, Dobutamine (1-3 micrograms/kg body wt min-1) and Metaraminol (0.5-1.5 micrograms/kg body wt min-1) in various doses were infused and the effects of these vasoactive agents were examined. Epidural analgesia decreased arterial pressure, pulmonary arterial pressure, pulmonary capillary wedge pressure and central venous pressure associated with marked decrease in cardiac index, stroke volume index, left ventricular and right ventricular stroke work without changes in systematic vascular resistance, pulmonary vascular resistance or heart rate. The infusion of Metaraminol caused a marked increase in arterial pressure, pulmonary arterial pressure, wedge pressure and central venous pressure. Calculated variables of stroke volume, systemic vascular resistance, left and right stroke work and cardiac work increased significantly. The infusion of Dobutamine caused a marked increase in arterial and pulmonary arterial pressure, wedge pressure, central venous pressure and cardiac index associated with those calculated changes of left and right stroke work and cardiac work, which were increased markedly. On the other hand, heart rate, stroke volume and pulmonary vascular resistance did not show any remarkable changes. Our study indicates that the fall in arterial blood pressure associated with epidural block may be due to marked decrease in cardiac output, and the infusion of Dobutamine is one of the desirable methods to counteract the hypotensive episode.

Catecholamine metabolism in recurrent hereditary polyserositis. Pathogenesis of acute inflammation: the retention-leakage hypothesis.

Recurrent hereditary polyserositis (RHP), also known as familial Mediterranean fever, is a genetically-determined disease characterized by paroxysmal attacks of peritonitis, pleuritis, arthritis or inflammation of other serous membranes. We have previously suggested that the pathogenesis of this disease seems to be related to abnormal catecholamine metabolism. This study compares the plasma and urine catecholamine profile in patients with RHP during different clinical states to that in controls. In RHP there were lower plasma and higher urine dopamine levels in the asymptomatic state and during attacks, while norepinephrine levels remain unchanged. However, plasma epinephrine was significantly lower in the asymptomatic state but markedly higher during attacks. The urine epinephrine values in both situations were similar but significantly lower than in controls, suggesting abnormal renal excretion of epinephrine. The urine metanephrine was markedly elevated in the asymptomatic state compared to controls, but remained unchanged during the attacks, again suggesting defective renal clearance of metanephrine. Metaraminol infusion, which induces attacks in RHP patients, was associated with an increase in plasma dopamine and epinephrine (but not norepinephrine); yet the urinary levels of dopamine, epinephrine and metanephrine remained the same, confirming the dissociation between the plasma and urinary levels of these catecholamines, probably due to abnormalities in the renal clearance mechanism. We postulate that this dissociation leads to retention of these amines in the plasma which may subsequently leak through the serous membranes (the target organs) and incite an acute inflammatory process. Colchicine, the only known drug that protects against disease attacks, reduces the plasma levels of these amines, and thus may act by preventing retention that leads to leakage and subsequent inflammation.

Prolonged induced hypertension in the management of incipient cerebral infarction.

A patient operated upon for a carotico-cavernous fistula developed incipient cerebral infarction. Metaraminol was used for a period of eight days to produce a therapeutic elevation in blood pressure to prevent this complication. Its possible role in the management of similar complications in the post-operative period of intracranial aneurysms and post angiography is discussed.

Effect of acute blood pressure changes on signal averaged electrocardiogram.

An acute blood pressure elevation may cause ventricular ectopic rhythms, while its reduction may alleviate them. It is studied whether the blood pressure exerts some effect on parameters obtained by the signal averaged electrocardiogram. In 25 patients with either hypertension (8 cases) or ventricular ectopic rhythms (10 cases) or both (7 cases) the blood pressure was reduced by sodium nitroprusside (24 cases) and/or elevated with metaraminol (10 cases) and the signal averaging electrocardiogram was recorded under 2 or 3 pressure values on each patient. During the high pressure (193.6 +/- 20.1 mm Hg) the following differences were noted compared to the low pressure (77.4 +/- 15.2 less): longer QRS duration in all 25 patients (+9.92 +/- 10.51 ms, P < 0.001); longer low (< 40 microV) amplitude signals (LAS) in 18 patients (+6.94 +/- 10.93 ms, P < 0.005); lower root mean square voltage of the terminal 40 ms of the QRS in 22 patients (-15.73 +/- 21.60 microV, P < 0.005); and ventricular ectopic beat incidence higher in 8, lower in 1, and equal in 2 cases (with no arrhythmia in the other 14). The generally and focally reduced conduction, as suggested by the QRS and LAS prolongation, might contribute to the proarrhythmic effect of acute blood pressure elevation.

Emergency treatment of papaverine priapism.

We report a case of vasoactive-agent-induced priapism successfully treated in the emergency department with 10 mg of metaraminol injected into the corpora cavernosa.

Induced priapism and its management.

The authors present the seamy side of the beneficial practice to handle erectile impotence with papaverine or with the papaverine-Regitin combination. Attention is called to danger. The various forms of priapism are defined. In connection with 72 cases of priapism the attained results and the way to stop the priapic condition are described.

Uremic autonomic neuropathy: evaluation of ephedrine sulphate therapy for hemodialysis-induced hypotension.

The hemodynamic response to ephedrine sulphate were studied in a patient on maintenance hemodialysis therapy with chronic renal failure due to renal amyloidosis. The evaluation (including cardiac catheterization studies) and estimation of responses to Valsalva maneuvers before and after ephedrine administration documented the diagnosis of autonomic insufficiency. Oral ephedrine failed to influence the episodes of severe dialysis-induced hypotension. Also the patient did not benefit from the infusion of Aramine. These studies suggest that catecholamine stores of adrenergic nerves may be depleted in uremic patients with clinical signs of autonomic neuropathy.

[Metaraminol--an antidote in corpus cavernosum autoinjection therapy-induced prolonged erection]. / Metaraminol--ein Antidot bei SKAT-bedingter prolongierter Erektion.

Up to now 65 patients with erectile dysfunction were treated by means of corpus cavernosum-autoinjection-therapy (CAT). The only side effect observed were 6 prolonged erections, which could successfully be treated in 3 cases by puncture and aspiration of the corpora cavernosa. In another 3 cases prolonged erection subsided after an intracavernous injection of 2 mg metaraminol. Erection induced by CAT was immediately interrupted by metaraminol in 10 other patients.