Advanced Paramedical Science

Na aima and regurgitate is a unremarkably encountered problem in the nip department as it accompanies a army of designers ranging from seemingly benign conditions such(prenominal) as migraine and gastroenteritis to sloppedi bothy lethal conditions such pancreatitis and the acute abdomen.Studies from the U.S select shown that each year, al almost 8 million individuals present to the emergency department with complain of nausea and emesis, some(prenominal) as a principal complain or as a part of a nonher disease etiology (Braude, Soliz, Crandall, Hendey, Andrews, & Weichenthal, 2006, p. 77). malady and disgorge be not distinct disease entities. Rather, they ar symptoms which tin do-nothing be present in a wide rake of disease conditions and be con typefacered to be the end- blots of some(prenominal)(prenominal)(prenominal) pathological processes (Kloster fr follow throughalen and Enck cited in Kowalski, Rapps, & Enck, 2006 p.28). The term nausea refers to the subjecti ve feeling or the urge to regurgitate gastric table of contents (Kuver, Sheffield, & McDonald, n.d.).From a physiological point of view, this is associated with reduced gastric motility and increased smooth muscle tactual sensation of the small intestine. Moreover, at that place might in addition be the presence of revolutionise peristalsis in the small intestine, which do-nothing fix the feeling of close regurgitation (Bowen, n.d.).On the some other hand, vomiting refers to the forceful discharge of gastric contents (Kuver, Sheffield, & McDonald, n.d.) which is meant to serve the purpose of protecting the gastrointestinal nerve pathway from potentially baneful substances by preventing their entry and transit through the gastrointestinal tract (Kuver, Sheffield, & McDonald, n.d.).Vomiting, if recollective can support some(prenominal) potentially hazardous consequences such as dehydration, electrolyte imbalances, metabolic derangements, manifesting as alkalosis and even bleeding and esoph periodal perforation (Kuver, Sheffield, & McDonald, n.d.). Moreover, from the patients perspective, nausea and vomiting can be distressful and thus bewitch and timely management of these two conditions is imperative.The Physiology of Nausea and Vomiting an overview of the stimuli and pathway problematicFor several decades straight off, it has been established that the chemo receptor trigger regularise in the brain which is responsible for puking is the commonwealth posterema. This is a region turn up at the dorsal uprise of the medulla oblongata near the caudal end of the tetradth ventricle. It is one of the circumventricular organs and by the virtue of possessing a comparative degreely permeable blood-brain barrier, is sensitive to a variety of stimuli (Sanger & Andrews, 2006, p. 5).Thus, it plays an important role in vomitive. Studies have shown that there argon five main kinds of stimuli which can trigger nausea and vomiting via polar pathways viz. the presence of toxic materials in spite of appearance the gut lm, presence of toxins in the blood, a pathology within the gut, a primeval nervous system (CNS) foreplay or disturbances in the vestibular system (Sanger & Andrews, 2006, p. 5). The mechanism whereby each of these stimuli brings some nausea and vomiting is discussed below.The presence of toxic materials within the gut lumenThe presence of toxins, such as medicines has been shown to stimulate the enteroendocrine cells, such as the enterochromaffin cells, located in the gut mucosa and way out in the release of several mediators such as 5HT3, Substance P and CCK.This results in the stimulation of pneumogastric afferent neurons which be located in the abdomen. These neurons traverse through the inwardness tractus solitarius (NTS) and are projected to the dorsal brainstem, with some projection in to the area posterema (Sanger & Andrews, 2006, p. 5).Presence of toxins in the bloodToxins which have been absorbed and are circulating in the blood stream can directly stimulate the area posterema and cause induction of emetic (Sanger & Andrews, 2006, p. 5). This is the most common mechanism whereby ingested or parenterally administered do drugss, such as chemotherapeutic agents and other toxins such as drugs of abuse, invoke the emetic repartee.Gastrointestinal tract pathologiesCertain pathologies of the gastrointestinal tract, such as gastritis or hypertrophic pyloric stenosis can stimulate the vagal afferents or directly activate the pathways leading to emesis (Sanger & Andrews, 2006, p. 6).Central nervous system (CNS) stimuliCertain stimuli such as intense fear, anticipatory anxiety, hurt to the brain or a sudden increase in the intracranial pressure can induce emesis (Sanger & Andrews, 2006, p. 6). The mechanism involved in such a response has not yet been elucidated clearly.Disturbances in the vestibular systemAmongst other manifestations of disturbances in the vestibular system, such as d izziness, nausea and vomiting is also an important symptom. The vestibular system has been shown to directly stimulate the pathways involved in the emetic response and hence produce nausea and vomiting (Sanger & Andrews, 2006, p. 6).All these stimuli have been shown to stimulate various pathways which have one common event viz. the stimulation of the emetic center in the area posterema. (Kuver, Sheffield, & McDonald, n.d.). several(prenominal) receptors, twain central and peripheral, have been implicated in rescue to the highest degree emesis.Amongst these the most pertinent ones are Dopaminergic receptors (particularly D2), Histaminergic receptors (especially H1), Muscuranic receptors (including M3/M5), 5-hydroxytryptamine receptors, in particular, 5-HT3 and the neurokinnin receptor, NK1 (Sanger & Andrews, 2006, p. 8)Once any of the above mentioned stimuli are encountered, an afferent response as discussed above is generated. This results in the activation of the chemorecepto r trigger zone in the area posterema. Subsequently, a motor response is generated, whereby efferent pathways involving the cranial nerves V, VII, IX and X are activated. Moreover, autonomic responses are also generated (Kuver, Sheffield, & McDonald, n.d.).The vagal efferents to various muscle groups such as those located in the esophagus, corporation and the intestine are activated bringing active stimulation of these muscles (Sanger & Andrews, 2006, p. 6). Moreover, abdominal muscles, phrenic muscles and the diaphragm are also stimulated to bring about(predicate) the required increase in the intra-abdominal pressure. The conspiracy of both these cause leads to the regurgitation of the gastric contents.Moreover, this is also accompanied by various other manifestations such as an increase in salivation, brought about by the stimulation of the chorda tympani branch of the facial nerve, autonomic stimulation of the cardiovascular and respiratory systems and vasoconstriction of ski n vessels (Sanger & Andrews, 2006, p. 6). antiemetic drug drugs utilise in pre- hospital careNausea and vomiting are ordinarily encountered clinical problems. Over the years, several anti-emetic medications have been discovered to in effect alleviate the symptoms of nausea and vomiting.These drugs work by blocking the pathways involved in the initiation and production of emesis. Various drugs have been developed which block the divers(prenominal) receptors, both central and peripheral, involved in producing emesis.The anti-emetic medications which are used in common clinical practice can be grouped in to seven major categories according to their mode of carry through. These include anti-cholinergics, antiserotonins, antihistamines, Benzamides, Butyrophenones, Phenothiazines and steroids (Scuderi, 2003, p. 43).The mechanism of deed and the loony toonss of the four main anti-emetics used in Ambulance Services in Australia are discussed below1. Metoclopramide (Maxolon)Metoclopram ide has been used in clinical practice for several decades now as an antiemetic and a prokinetic agent (Walkembach, Bruss, Urban, & Barann, 2005, p. 50). These antiemetic functions are melodic theme to be brought about by the antagonistic action mechanisms of Metoclopramide on the dopamine (D2) receptors, both central and peripheral, and also on the 5HT3 receptors (Walkembach, Bruss, Urban, & Barann, 2005, p. 50).On the other hand, the prokinetic action of Metoclopramide are brought about by the relaxation of the pyloric sphincter muscle, the increase in the strength and frequence of peristalsis and an increase in the tone of the lower esophageal sphincter (Australasia, 2008).This drug is available in both tablet (white, round, 7mm in diameter) and barb (colorless(prenominal), aqueous solution) forms (Australasia, 2008). The maximum window pane of Metoclopramide commonly used in all age groups is up to 0.5 mg/kg body weight.The recommended dosage nourishment for adults is 10m g three propagation daily while for children it varies in the midst of 2.5mg-5mg three times daily (Australasia, 2008). The metabolism of Metoclopramide takes place in the liver and it is eliminated from the body preponderantly via the kidney. (Australasia, 2008)2. Prochlorperazine (Stemetil)Prochlorperazine is a phenothiazine which has been shown to block the dopamine receptors (D2) in the chemoreceptor trigger zone located near the area posterema. By blockage of these receptors, Prochlorperazine exerts its antiemetic actions. The recommended dosage of Prochlorperazine in is 10 mg intravenously (Goodman and Gilmans The Pharmacologic instauration of Therapeutic cited in Ernst, Weiss, Park, Takakuwa, & Diercks, 2000, p. 92).In emergency practice, IV administration of 2.5-10 mg of Prochlorperazine at a rate of up to 5mg/min is recommended for adults. The maximum dose should not exceed 40mg per day. Moreover, IM injections of this drug are also available. They are administered at a dose of 5-10 mg every 3-4 moments (Bartlett, 2009, p. 861).3. Ondansetron (Zofran)Ondansetron is a carbazole derivative and is a potent antiemetic drug which is widely used in alleviating the symptoms of nausea and vomiting associated with chemo- and radio- therapies and also in the management of post-operative nausea and vomiting (Scuderi, 2003, p. 59). Its pro be mechanism of action is via selective antagonism at the level of the 5 HT3 receptors (Scuderi, 2003, p. 59).Chemotherapeutic agents are eyeshot to bring about nausea and vomiting via the stimulation of enterochromaffin cells in the gut mucosa leading to 5HT3 production and subsequent vagal stimulation. This pathway is jam by 5HT3 antagonists such as Ondansetron.Ondansetron has been shown to have a short half life of approximately 3 to 5 h (Ho & Gan, 2006, p. 607). The recommended dosage of Ondansetron varies between 8-16 mg twice daily (Bartlett, 2009).4. promethazine (Phenergan)promethazine is also a phenothiazine un less is shown to have dual modes of action. It not only blocks the dopamine receptors (D2) but has also been shown to have anti-H1 histamine receptor do. It is used for a wide range of purposes including in the treatment of motion sickness, vertigo and even allergies (Bartlett, 2009, p. 869).The recommended oral dose of Promethazine is 25 mg twice daily. It can also be administered intravenously at a dose of 12.5-25 mg every four hours. The maximum dose is 150 mg/day (Bartlett, 2009, p. 869).PART IIThere are several clinical conditions which can present with the symptoms of nausea and vomiting. Amongst these the most common condition is gastroenteritis, migraines and pancreatic amongst others.The adequate and timely management of patients with nausea and vomiting has posed a challenge for the clinicians for several decades and although several effective anti-emetics have been discovered, there has been a quest for a single anti-emetic which is efficient, fast acting and relatively safe.In the practice of ambulance goods and emergency situations, different anti-emetics are commonly used including Metoclopramide, Chlorpromazine, Ondansetron and Promethazine. Amongst these, in my opinion, the most suitable drug for use in the ambulance service and emergency departments is Metoclopramide.This is because on comparing the onset of action, clinical efficacy and face effect profiles of the most common anti-emetic agents, it is apparent that Prochlorperazine is superior to all other agents used. Moreover, its cost, handiness and easy administration make it suitable for use in the emergency practice. Following is a comparison of the four most commonly used anti-emetic drugs.A common concern with the use of any drug is its sentry go and look effect profile. Safety becomes more important while transaction with patients in the emergency or ambulance care since limited resources, time and forcefulness are available in such settings, and the prime concern is the stabi lization of the patient and alleviation of his symptoms.Drugs which have potentially unsafe need to be administered with caution and the patients need to be monitored for the occurrence of adverse make. This is not workable in emergency and ambulance practice and thus the paragon drugs for use in such settings are those which have no or minimal ramp cause.With Metoclopramide, there is a 10-20% incidence of side effects and these side effects are mild. The most common side effects observed with this drug are CNS effects such as anxiety, restlessness and insomnia which can vary in severity (Australasia, 2008).Moreover, it has also been shown to cause fatigue and on occasion can cause extrapyramidal side effects. Another relatively common side effect of Metoclopramide is gynecomastia which occurs as a result of enhanced prolactin secernment (Kuver, Sheffield, & McDonald, n.d.).A rare complication associated with the use of Metoclopramide is Neuroleptic Malignant Syndrome which is a medical exam emergency and can lead to death. However, it is observed in only less than 1 in 10,000 cases (Australasia, 2008) .On the other hand, the phenothiazines including Prochlorperazine and Promethazine have been shown to have a greater number of side effects. Amongst these the ones which arouse the most concern are extrapyramidal symptoms.Extrapyramidal symptoms can range from tremor to akathisia and the potentially hazardous tardive dyskinesias (Australia, 2009). Moreover, they can also manifest as dystonic reactions are similar to the manifestations of Parkinsons disease. slight commonly, Neuroleptic Malignant Syndrome, which is a medical emergency, can also result from the use of these drugs.These effects are thought to be caused due to the central antidopaminergic properties of the phenothiazines on the dopamine receptors. The occurrence of these symptoms is noticed most commonly within 36 hours of initiation of treatment. However, these symptoms are reversible and o nce the drug is discontinued, they melt down within 24 hrs (Australasia, 2008).It is important to note that with Metoclopramide, the occurrence of extrapyramidal side effects is not very common. On the other hand, the phenothiozones such as Prochlorperazine and Promethazine have a much greater incidence of these side effects.Drotts and Vinson (1999) in their study showed that with the use of Prochlorperazine, incidence of akathisia was 44% within 1 hour and 5% within 48 hours. (Braude, Soliz, Crandall, Hendey, Andrews, & Weichenthal, 2006, p. 181). Other studies, such as those of Ernst et. al., have supported these findings.These extrapyramidal symptoms, if severe, have to be treated with intravenous infusions of an anti-cholinergic agent such as diphenhydramine (Ernst, Weiss, Park, Takakuwa, & Diercks, 2000, p. 92).Other common side effects of phenothiazines include constipation, brumous vision, mild elevation of the hepatic enzymes (if the patient develops cholestatic jaundice), ECG changes, arrhythmias and hypotension (Australia, 2009).Hypotension in patients who are already dehydrated due to vomiting can lead to epochal patient distress and is also important from the point of view of wellness care professionals, as it poses difficulties in patient management in emergency and ambulance settings. Moreover, most phenothiazines, in particular Promethazine are known to cause sedation due to histamine blockade.Promethazine has also been shown to reduce the seizure threshold. Due to the pot of serious adverse effects of Promethazine the Food and Drug judicature (FDA) has restricted its use in children under two years of age (DeCamp, Byerley, Doshi, & Steiner, 2008, p. 859).As compared to Metoclopramide, Ondansetron has relatively lesser side effects. The most commonly encountered adverse effects of this agent include headaches, constipation and mild elevation of serum transaminases (Kuver, Sheffield, & McDonald, n.d.).But this drug is not preferred over othe r anti-emetic agents due to its cost and availability issues (Ernst, Weiss, Park, Takakuwa, & Diercks, 2000, p. 92). Moreover, it is used more commonly to prevent post-operative nausea and vomiting and in patients receiving chemotherapy and its role in acute settings has not been extensively studied.Pregnancy is one of the most common conditions which present with nausea and vomiting. Amongst the commonly available anti-emetics only a few are safe to use in pregnancy.Studies have shown Metoclopramide to be safe for use during pregnancy and this drug has not been shown to cause any long term complications in children of mothers using it during pregnancy (Srensen, Nielsen, Christensen, Tage-jensen, Ekbom, & Baron, 2000). Similarly the safety device of Ondansetron has also been proven by several studies conducted recently (Einarson, Maltepe, Navioz, Kennedy, Kennedy, & Koren, 2004, p. 940).However, both Promethazine and Prochlorperazine belong to Category C and thus have limited use i n pregnancy (Australia, 2009).Another advantage of Metoclopramide is its ability to provide faster residue from the symptoms of nausea and vomiting. Metoclopramide has been shown to have a rapid onset of action. Following IV administration, its effects start manifesting in around 1 to 3 minutes, whereas quest intramuscular administration, 10 to 15 minutes is required (Australasia, 2008). This rapid action makes it suitable for use in emergency practice,Although there is a paucity of studies comparing the cost effectiveness of Metoclopramide with other antiemetics, studies comparing the cost-effectives in patients undergoing chemotherapy have shown that Metoclopramide to be more cost effective than Ondansetron (Ballatori, et al., 1994).Thus, in conclusion, keeping the side effect profiles, the availability and cost effectiveness of all the anti-emetics in view, in my point of view Metoclopramide is best suited for use in ambulant settings. Metoclopramide has several benefits over other anti-emetics.It has a fast onset of action which makes its practical for use in emergency settings. Moreover, it has lesser and milder adverse effects as compared to other anti-emetics. In addition, it can be used in all age groups and is safe in pregnancy. Thus, all these properties make Metoclopramide ideal for use in ambulatory care settings.ReferencesAustralasia, V. P. 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