Drugs Used to Treat Respiratory Emergencies PDF

Drugs Used to Treat Respiratory Emergencies Module 8  Introduc7on Respiratory distress is one of the most common pa6ent presenta6ons encountered by prehospital professionals. Acute respiratory distress affects the young and old, male and female, and...

Drugs Used to Treat Respiratory Emergencies Module 8  Introduc7on Respiratory distress is one of the most common pa6ent presenta6ons encountered by prehospital professionals. Acute respiratory distress affects the young and old, male and female, and people of all ethnici6es. Although the underlying pathologic condi6on causing the respiratory distress may be different, with the excep6on of acute pulmonary edema most of the prehospital care is aimed at treatment of reversible bronchial constric6on, or bronchospasm. Advanced life support (ALS) interven6ons, including respiratory medica6on administra6on, have been shown to significantly reduce mortality in pa6ents with respiratory distress.  Oxygen iii Oxygen is the most commonly used medica6on in the prehospital seFng. As with any drug, oxygen has associated risks, as well as benefits. Oxygen is used daily by basic and advanced prehospital providers, some6mes with liHle considera6on to its pharmacologic proper6es. The use of oxygen has become increasingly controversial. In situa6ons such as neonatal resuscita6on, chronic obstruc6ve pulmonary disease (COPD) exacerba6ons, and acute coronary syndrome, oxygen use is now carefully 6trated to prescribed oxygen satura6on ranges, rather than applied indiscriminately.  in Poisons ttt in b y fi iii iii Oxygen am EMS providers should an6cipate addi6onal changes as ongoing research in this area leads to guideline updates and a significant paradigm shiO from tradi6onal approaches to oxygen delivery. On occasion, prehospital providers encounter pa6ents with COPD, who require con6nuous oxygen while at home. Con6nuous oxygen can require a transtracheal catheter, which is inserted surgically. Transtracheal catheters, like nasal cannulas, are used for long- term oxygen therapy in pa6ents with chronic lung disease. Some pa6ents find that the long-term use of nasal cannulas is irrita6ng to the nose at night; such pa6ents may receive transtracheal catheters, which are held in place by a necklace. ushedfaces gutIndicarcopoising  Bronchodilators _aaagfmp Pa6ents with asthma (an inflammatory disease of the lungs characterized by typically reversible airway obstruc6on) and COPD have respiratory distress from a func6onal narrowing of the conduc6ng airways. As a result, these pa6ents report that they feel as though they are breathing through a straw. Spasm of the bronchial smooth muscle, also known as bronchospasm, results in a decrease in the airway diameter. Another factor that contributes to respiratory distress is edema of the mucosa that lines the respiratory tract. This inflammatory edema results in a thickening of the mucosal linings and a resultant decrease in airway diameter.  Bronchodilators Increased secre6ons also contribute to the distress of these pa6ents. Any reduc6on of the radius of the airway, from either bronchospasm or mucosal edema, can have a profound effect on the flow of gas. Bronchodilators can be divided into selec6ve and nonselec6ve agents. Selec6ve agents act preferen6ally on the bronchial smooth muscle and improve the pa6ent’s condi6on while minimizing side effects. dilation Broncho Beta2 agonists are sympathomime6c medica6ons that target selective the beta2 receptors and cause relaxa6on of bronchial smooth muscle without s6mula6ng tachycardia or hypertension. e  Bronchodilators some bamboo Most of these medica6ons are selec6ve for the beta2 receptor; however, paramedics must be cau6ous because excessive doses can produce the undesirable effects seen with alpha and beta1 s6mula6on (e.g., tachycardia and positiveeffect hypertension). ftp.ttt I Use beta2 agonists with cau6on in pa6ents with a history of ronotropicanotr Fntain heart disease, and always monitor the electrocardiogram during and aOer treatments. salloutenT Examples of beta2 agonists include albuterol (Proven6l), terbutaline (Brethine), formoterol (Foradil), and pirbuterol (Maxair).  Bronchodilators Nonselec6ve agents act on alpha, beta1, and beta2 adrenergic receptors. S6mula6on of the alpha receptors causes constric6on of peripheral blood vessels and results in blood pressure eleva6on. Beta1 receptors, which are predominantly located in cardiac 6ssue, increase heart rate and cardiac contrac6lity when s6mulated. S6mula6on of the beta2 receptors results in bronchodila6on by relaxa6on of bronchial smooth muscle. Racemic epinephrine is an example of a nonselec6ve bronchodilator. adrenergicagonist  Overview of Asthma Acute asthma aHacks can affect pa6ents of all ages. Asthma is caused by a trigger reac6on. autoimmune Triggers can be either intrinsic (within the body) or extrinsic Allergic (outside the body). Examples of intrinsic triggers include exer6on, such as an aHack triggered by exercise, and anxiety related to stress. Examples of external triggers are reac6ons to animal dander, dust, insect droppings, pollen, and cleaning chemicals. jiiiiii.aeri I first line It.EE i ii i ii  Management A main focus in management of asthma is for the pa6ent to avoid the triggers that ini6ate aHacks whenever possible and mi6gate the effects of these triggers. When EMS is called, these goals have not been achieved and pa6ent management is aimed at the reversal of acute bronchospasm. Although parenteral medica6ons can be used to treat pa6ents with asthma, the first line of medica6ons is inhaled beta2-specific drugs. If inhaled bronchodilators fail, intravenous (IV) medica6ons are then administered to reduce bronchospasm and inflamma6on.  Management Berazagonist with a slight effect on Betal Albuterol (Proven6l, Ventolin) is by far the most common inhaled drug used to treat reversible bronchospasm. Albuterol is one of several inhaled bronchodilators that have been developed to target only the beta2 receptor. Prior beta2 agonists had varying degrees of effect on alpha and beta1 receptors, and s6mula6on of these sites may cause unwanted reac6ons in already compromised pa6ents. For example, s6mula6on of alpha receptors could cause unwanted vasoconstric6on, and s6mula6on of beta1 receptors could cause increased heart rate. As such, more 6me between treatments was required to compensate for the unwanted, predominantly beta1, adverse effects.  Management Levalbuterol (Xopenex) is a newer “purified” version of albuterol, which had been believed to cause fewer adverse effects than albuterol. Both appear to be quite effec6ve in acute treatment of asthma exacerba6ons. The first-genera6on drugs had significant beta1 effects along with beta2 effects. Second-genera6on drugs were more beta2 specific but would s6ll increase heart rate and could not be given close together. Finally, third-genera6on medica6ons predominantly targeted the beta2 receptors.  Management When given by inhala6on and specifically targe6ng the smooth muscle in the airways, they had liHle or no systemic effect. Without these systemic effects, mul6ple and con6nuous treatments could be given for moderate to severe exacerba6ons. Ipratropium bromide (Atrovent) is used in more severe exacerba6ons of asthma or in cases in which the pa6ent has a limited response to treatment with albuterol. Ipratropium bromide is not an adrenergic agent but is considered an an6cholinergic. atropine  Management In more severe cases of bronchospasm, addi6onal treatment with ipratropium bromide has provided greater symptoma6c relief than albuterol used as a single agent. Adrenergic agents such as albuterol act more centrally in the bronchial tree, whereas cholinergic agents such as ipratropium are more effec6ve in the peripheral airways. Adrenergic agents are more effec6ve in asthma, whereas the peripheral ac6on of ipratropium provides greater benefits in pa6ents with COPD. Albuterol/ipratropium (Combivent) is a combina6on product that takes advantage of the different mechanisms of ac6on and anatomic sites of ac6on of albuterol and ipratropium bromide to deliver both medica6ons in a single prepara6on.  Second-Line Therapy for Acute Exacerba7on of Asthma The clinical picture of a pa6ent having an asthma aHack or exacerba6on of COPD is that of a pa6ent gasping for breath, using accessory muscles of respira6on, and wheezing. In asthma and COPD, bronchodilators provide symptoma6c therapy but do not directly treat the underlying and ini6a6ng lung condi6on. In cases in which a prolonged transport 6me is likely, consider cor6costeroids to treat the inflammatory processes involved in both asthma and COPD. The most commonly used cor6costeroids are longacting methylprednisolone and dexamethasone. Hydrocortisoneshortacting intergedent Both appear to be equally effec6ve in managing moderate or severe asthma symptoms.  Second-Line Therapy for Acute Exacerba7on of Asthma If there are concerns regarding pa6ent compliance, providers may choose to administer a single dose of dexamethasone over a longer oral course of another cor6costeroid. Peak expiratory flow rate (PEFR) is an objec6ve assessment that can guide a provider’s determina6on of the severity of an exacerba6on; the pa6ent’s response to therapy; and the indica6on for therapy, such as the start of steroids. When the ini6al PEFR is less than 50% of predicted, cor6costeroids should be administered aOer ipratropium bromide administra6on.  Second-Line Therapy for Acute Exacerba7on of Asthma Cor6costeroids should also be considered when the PEFR does not improve by at least 10% aOer bronchodilator therapy or when the PEFR is less than 70% aOer 1 hour of therapy. iiii Aminophylline and other methylxanthines work to reduce the smooth muscle bronchospasm associated with acute respiratory distress. These medica6ons were once rou6nely administered as second-line agents for severe asthma exacerba6ons. Their role has greatly diminished and they are no longer recommended as rou6ne therapies. Glucocorticoids É ji neogenesis receptors oncose aminoacid II.it nterluki E iiiiii.IT ks Decreases ftij fi Y HPAA Ifsuddulystoped it causes adrenal crisis  Second-Line Therapy for Acute Exacerba7on of Asthma myson Éiii r calsium antagonist workas Magnesium sulfate has been demonstrated to decrease bronchospasm in a subset of asthma6c pa6ents. Pa6ents who do not show an adequate response to beta2 agonist medica6ons can have a favorable response to magnesium sulfate. Magnesium sulfate should not be used in all pa6ents having an asthma6c aHack; however, consider using magnesium in pa6ents who do not improve aOer beta agonist therapy. For years, epinephrine administered subcutaneously was the treatment of choice for young pa6ents with asthma. amightcause tachycardia hypertension Epinephrine does have strong and desirable beta2 effects; however, it also has strong and undesirable alpha and beta1 effects.  Second-Line Therapy for Acute Exacerba7on of Asthma Rebound bronchospasm can be a secondary problem with the administra6on of epinephrine in the management of an asthma aHack. Although epinephrine is effec6ve when ini6ally administered, its effects are short- lived. If considering epinephrine for use in adults with asthma, do not underes6mate beta1-mediated cardiac complica6ons such as tachycardia and hypertension. For these reasons, epinephrine should be used with cau6on, if at all, in the treatment of the pa6ent with asthma. Epinephrine may s6ll be indicated if an anaphylac6c reac6on is suspected.  Chronic Obstruc7ve Pulmonary Disease COPD is the classifica6on for diseases that cause obstruc6on in the pulmonary tree. The two most common diseases are emphysema and chronic bronchi6s. Both pathologic condi6ons cause an increase in sputum produc6on and resultant bronchospasm. As the increase in sputum worsens, so can the irrita6on and the bronchospasm. Ini6al treatment of mild to moderate COPD exacerba6on is aimed at reducing bronchospasm and mobilizing and clearing the sputum from the airways.  Management In severe exacerba6ons, treatment is first aimed at oxygena6on and ven6la6on of the pa6ent. Oxygena6on needs to be provided with care. Pa6ents with a long-standing history of COPD breathe on what is known as a hypoxic respiratory drive. This means that the pa6ent requires a mild degree of hypoxia to con6nue breathing. If the pa6ent is given too much oxygen, the hypoxic respiratory drive is removed, as well as the pa6ent’s s6mulus for spontaneous respira6ons.  Management Therefore, when monitoring these pa6ents, an SaO2 level in the low 90s as measured by pulse oximetry is considered adequate. Bronchodilators and steroids are used to manage COPD in a similar fashion as for the treatment of asthma. The End