1	Prehospital Emergency Pharmacology CHAPTER 8 Drugs Used in the Treatment of Respiratory Emergencies
2	Asthma
3	Asthma Chronic inflammatory disorder of the airways Major characteristic is reversible lower airway obstruction This obstruction is caused by edema, mucus, and smooth muscle spasm; typically, all three factors are involved.
4	Asthma (cont.) Air becomes trapped behind the obstruction Preventing continued ventilation of the alveoli Oxygen–carbon dioxide exchange may be severely impaired
5	Asthma (cont.) Triggered by one of many different factors A two-phase reaction occurs: First phase is the release of histamine (1-2 hours) Second phase is the inflammation of the bronchioles (6-8 hours)
6	Asthma (cont.) Medical interventions: First phase can be reversed with the inhaled bronchodilators Second phase requires anti-inflammatory agents (corticosteroids)
7	Status Asthmaticus Severe, prolonged asthma attack that cannot be broken by repeated doses of medication Symptoms: Distended chest from continual air trapping Breaths may be absent Patient is usually exhausted and severely acidic
8	Management of Asthma Correct hypoxia Reverse bronchospasm Treat inflammatory changes
9	Management of Asthma (cont.)
10	Epinephrine
11	Class Sympathetic agonist
12	Description A naturally occurring catecholamine A potent α- and β-adrenergic stimulant Its effect on β-receptors is more profound.
13	Mechanism of Action Causes bronchodilation due to its effects on β₂-adrenergic receptors Used to treat the bronchoconstriction accompanying asthma and COPD Also effective in treating bronchoconstriction associated with anaphylaxis
14	Pharmacokinetics Onset 3-10 minutes, subcutaneous (SC) Peak effects 20 minutes (SC) Duration 20-30 minutes (SC) Half-life N/A
15	Indications Bronchial asthma Exacerbation of some forms of COPD Anaphylaxis
16	Contraindications Patients with underlying cardiovascular disease or hypertension Patients with profound anaphylactic reactions are usually peripherally vasoconstricted, which will delay absorption of the drug from the subcutaneous site of injection. In these cases, epinephrine 1:10,000 should be administered intravenously.
17	Precautions Should be protected from light Tends to be deactivated by alkaline solutions Any patient receiving epinephrine 1:1000 should be carefully monitored for changes in blood pressure, pulse, and ECG.
18	Side Effects Palpitations Anxiety Tremulousness Headache Dizziness Nausea and vomiting Can cause myocardial ischemia
19	Interactions Can be intensified in patients who are taking antidepressants
20	Dosage 0.3 to 0.5 mg of 1:1000 subcutaneously Weight- and condition-dependant 0.3 mg is usual starting dose for adults 0.01 mg/kg SC for pediatrics 1:1000 should only be administered SC or IM.
21	Albuterol Proventil, Salbutamol, Ventolin
22	Class Sympathetic agonist
23	Description A sympathomimetic that is selective for β₂-adrenergic receptors
24	Mechanism of Action Selective β₂-agonist with a minimal number of side effects Causes prompt bronchodilation Duration of action of approximately 5 hours
25	Pharmacokinetics Onset 5-15 minutes (inhaled) Peak effects 1-1.5 hours Duration 3-6 hours Half-life < 3 hours
26	Indications Bronchial asthma Reversible bronchospasm associated with chronic bronchitis and emphysema
27	Contraindications Known history of hypersensitivity
28	Precautions Vital signs must be monitored. Caution should be used with: Elderly patients Those with cardiovascular disease Those with hypertension Lung sounds should be auscultated before and after each treatment.
29	Side Effects Palpitations Anxiety Dizziness Headache Nervousness Tremor Hypertension Arrhythmias Chest pain Nausea and vomiting
30	Interactions Possibility of side effects increases when administered with other sympathetic agonists β-blockers may blunt pharmacological effects
31	Dosage Administered by metered-dose inhaler or small-volume nebulizer 2 sprays when using a metered-dose inhaler Each spray delivers 90 µg
32	Dosage (cont.) In a nebulizer, dose is 2.5 mg 0.5 mL of a 0.5% solution diluted in 2.5 mL of normal saline Delivered over 5 to 15 minutes Also available in the Rotohaler form A 200-µg Rotocap is inhaled
33	Levalbuterol Xopenex
34	Class Sympathetic agonist
35	Description A sympathomimetic that is selective for β₂-adrenergic receptors
36	Mechanism of Action Causes relaxation of bronchial smooth muscle Decreases airway resistance and increases vital capacity A chemical variant of albuterol with greater affinity for the β₂-adrenergic receptors
37	Pharmacokinetics Onset 5-15 minutes Peak effects 1-1.5 hours Duration 3-6 hours Half-life 3.3 hours
38	Indications Used in the treatment of bronchospasm associated with reversible obstructive airway disease: Asthma Chronic bronchitis Emphysema
39	Contraindications Known hypersensitivity to the drug
40	Precautions Should be used with caution in patients with cardiac ischemia Lung sounds should be auscultated before and after each treatment.
41	Side Effects Tremors Anxiety Dizziness Headache Insomnia Nausea Palpitations Tachycardia Hypertension
42	Interactions Side effects increase when administered with other sympathetic agonists β-blockers may blunt pharmacologic effects
43	Dosage 0.63 mg in 3.0 mL normal saline Every 6 to 8 hours via nebulizer In children < 12 y/o: 0.31 mg in 3.0 mL normal saline Three times a day
44	Racemic Epinephrine microNEFRIN, Vaponefrin
45	Class Sympathetic agonist
46	Description Slightly different chemically from the other epinephrine compounds Compounds that differ only in chemical arrangement are called isomers This particular form frequently used in children to treat croup
47	Mechanism of Action Stimulates both α- and β-adrenergic receptors Has a slight preference for β₂-adrenergic receptors and causes bronchodilation Also has some effect in relieving the subglottic edema associated with croup
48	Pharmacokinetics Onset < 5 minutes Peak effects 5-15 minutes Duration 1-3 hours Half-life N/A
49	Indications Used to treat croup (laryngotracheobronchitis)
50	Contraindications Should not be used in the management of epiglottitis
51	Precautions Can result in tachycardia and possibly dysrhythmias Vital signs should be monitored. Many patients develop “rebound worsening” 30 to 60 minutes after the initial treatment. Patients receiving racemic epinephrine should be observed for at least 24 hours.
52	Dosage 0.25 to 0.75 mL diluted with 2 mL normal saline (2.25%) Administered via aerosol nebulizer Should not be repeated Given only by inhalation
53	Terbutaline Brethine, Bricanyl
54	Class Sympathetic agonist
55	Description A synthetic sympathomimetic that is selective for β₂-adrenergic receptors
56	Mechanism of Action Causes immediate bronchodilation with minimal cardiac effects Onset of action is similar to epinephrine Also used to suppress preterm labor
57	Pharmacokinetics Onset < 5 minutes (SC), 5-30 minutes (inhaled) Peak effects 30-60 minutes (SC), 1-2 hours (inhaled) Duration 1.5-4 hours (SC), 3-4 hours (inhaled) Half-life 3-4 hours
58	Indications Bronchial asthma Reversible bronchospasm associated with: Chronic bronchitis Emphysema
59	Contraindications Known history of hypersensitivity
60	Precautions Vital signs must be monitored. Caution should be used with: Elderly patients Those with cardiovascular disease Those with hypertension Lung sounds should be auscultated before and after each treatment.
61	Side Effects Palpitations Anxiety Dizziness Headache Nervousness
62	Interactions Possibility of side effects increases when administered with other sympathetic agonists β-blockers may blunt pharmacological effects
63	Dosage 2 inhalations, 1 minute apart, from a metered-dose inhaler Can be 0.25 mg by SC injection Can be repeated in 15 to 30 minutes
64	Metaproterenol Alupent
65	Class Sympathetic agonist
66	Description Sympathomimetic that is selective for β₂-adrenergic receptors
67	Mechanism of Action An effective bronchodilator
68	Pharmacokinetics Onset 1 minute Peak effects 1 hour Duration 1-5 hours Half-life N/A
69	Indications Bronchial asthma Reversible bronchospasm associated with: Chronic bronchitis Emphysema
70	Contraindications Patients with cardiac dysrhythmias Patients with significant tachycardia
71	Precautions Vital signs must be monitored. Caution should be used with: Elderly patients Those with cardiovascular disease Those with hypertension Lung sounds should be auscultated before and after each treatment.
72	Side Effects Palpitations Anxiety Dizziness Headache Nervousness
73	Interactions Possibility of side effects increases when administered with other sympathetic agonists β-blockers may blunt pharmacological effects
74	Dosage Administered by metered-dose inhaler Each spray contains 0.65 mg Usual dose is 2-3 inhalations, 1 minute apart Via nebulizer, 0.2-0.3 mL in 2.5 ml of saline Administered over 5-15 minutes
75	Aminophylline Somophyllin
76	Class Xanthine
77	Description A xanthine bronchodilator that sometimes proves effective in cases where sympathomimetics have not been effective
78	Mechanism of Action Achieves its bronchodilation effects via a different mechanism than the sympathomimetics Relaxes bronchial smooth muscle with no adrenergic effect Also stimulates the respiratory center in the brain Has mild diuretic properties; increases the heart rate and cardiac output
79	Pharmacokinetics Onset 15 minutes Peak effects 15 minutes Duration Variable Half-life 4 hours
80	Indications Bronchial asthma Reversible bronchospasm associated with: Chronic bronchitis Emphysema Congestive heart failure Pulmonary edema
81	Contraindications Known history of hypersensitivity Should not be used in patients who have uncontrolled cardiac dysrhythmias
82	Precautions Caution should be used with a patient who has a history of cardiovascular disease or hypertension. Be alert for any signs of cardiac irritability: Premature ventricular contractions (PVCs) Tachycardia Hypotension can occur following rapid administration.
83	Side Effects Tachycardia Dysrhythmias Palpitations Chest pain Nervousness Headache Seizures Nausea and vomiting
84	Interactions Should not be administered to patients who are on chronic theophylline therapy until drug levels are obtained Concomitant use with β-blockers and drugs of the erythromycin class of antibiotics may lead to theophylline toxicity.
85	Dosage Two major regimens are used. Each delivers 2-5 mg/kg Method 1 is for patients in whom fluid overload or edema does not appear to be present. Method 2 is for patients with CHF, or if additional fluids might be dangerous.
86	Dosage (cont.) Method 1: 250 or 500 mg in 90 or 80 mL of D₅W Done with a 100-mL IV bag or with a Buretrol- or Volutrol-type administration set Infused over 20 to 30 minutes Slow infusion reduces chances of dysrhythmias
87	Dosage (cont.) Method 2: 250 or 500 mg in 20 mL of D₅W Done with a 100-mL IV bag or with a Buretrol- or Volutrol-type administration set Infused over 20 to 30 minutes Slow infusion reduces chances of dysrhythmias
88	Ipratropium Atrovent
89	Class Anticholinergic
90	Description An anticholinergic (parasympatholytic) bronchodilator that is chemically related to atropine
91	Mechanism of Action Causes bronchodilation Dries respiratory tract secretions Acts by blocking acetylcholine receptors, thus inhibiting parasympathetic stimulation
92	Pharmacokinetics Onset Variable Peak effects 1.5-2 hours Duration 4-6 hours Half-life 1.5-2 hours
93	Indications Bronchial asthma Reversible bronchospasm associated with: Chronic bronchitis Emphysema
94	Contraindications Known history of hypersensitivity Is not indicated for the acute treatment of bronchospasm, for which rapid response is required
95	Precautions Vital signs must be monitored. Caution should be used with: Elderly patients Those with cardiovascular disease Those with hypertension Lung sounds should be auscultated before and after each treatment.
96	Side Effects Palpitations Anxiety Dizziness Headache Nervousness Rash Nausea and vomiting
97	Interactions Few interactions in the prehospital setting
98	Dosage Usually administered with a β-agonist 500 mg is placed in a small-volume nebulizer with or without a β-agonist. Also available in a metered-dose inhaler
99	Magnesium Sulfate
100	Class Mineral
101	Description A salt that dissociates into the magnesium cation (Mg²⁺) and the sulfate anion when administered Magnesium is an essential element in numerous biochemical reactions that occur within the body.
102	Mechanism of Action Acts as a physiological calcium channel blocker and blocks neuromuscular transmission Used in the management of preterm labor and the hypertensive disorders of pregnancy
103	Pharmacokinetics Onset Immediate (IV), 1 hour (IM) Peak effects Variable Duration 1 hour Half-life N/A
104	Indications Severe bronchospasm Refractory V-fib and pulseless V-tach After myocardial infarction for prophylaxis of dysrhythmias Torsade de pointes (multiaxial V-tach)
105	Contraindications Patients who are in shock Persistent, severe hypertension Third-degree atrioventricular (AV) block Patients who routinely undergo dialysis Known decreased calcium levels
106	Precautions Administer slowly to minimize side effects Use continuous cardiac monitoring Calcium salts should be available as an antidote for magnesium sulfate in case serious side effects occur.
107	Side Effects Flushing Sweating Bradycardia Decreased deep tendon reflexes Drowsiness Respiratory depression Dysrhythmias Hypotension Hypothermia Itching and rash
108	Interactions Can cause cardiac conduction abnormalities if administered in conjunction with digitalis
109	Dosage 2 g over 2-5 minutes
110	Methylprednisolone Solu-Medrol
111	Class Corticosteroid and anti-inflammatory
112	Description A synthetic steroid with potent anti-inflammatory properties
113	Mechanism of Action Inhibits many of the substances that cause inflammation (cytokines, interleukin, interferon) Inhibits the synthesis of pro-inflammatory enzymes Considered an intermediate-acting steroid
114	Pharmacokinetics Onset Variable Peak effects 4-8 days (IM) Duration 1-5 weeks (IM) Half-life 3.5 minutes
115	Indications Severe anaphylaxis Asthma COPD Urticaria (hives)
116	Contraindications No major contraindications in the acute management of severe anaphylaxis
117	Precautions Single dose is all that should be given in the prehospital phase of care. Long-term steroid therapy can cause gastrointestinal bleeding, prolonged wound healing, and suppression of adrenocortical steroids.
118	Side Effects Fluid retention Congestive heart failure Hypertension Abdominal distension Vertigo Headache Nausea Malaise Hiccups
119	Interactions Few interactions in the prehospital setting
120	Dosage 125 to 250 mg IVP May be administered IV or IM Intravenous route is preferred
121	Rapid-Sequence Induction
122	Rapid-Sequence Induction Preoxygenate with 100% O₂ for 5 minutes Establish IV with large-bore catheter Monitor ECG, SpO₂, waveform capnography, and vital signs Perform a thorough neurological exam Prepare for rapid administration of a neuromuscular blocker
123	Rapid-Sequence Induction (cont.) Assemble and prepare ETT equipment Administer lidocaine 1.5 mg/kg IVP if head is injured or ICP is suspected Administer atropine 1.0 mg IVP if: Bradycardia is present Cervical-spine injury Patient is under age 16 Prepare paralytic agents
124	Rapid-Sequence Induction (cont.) Administer fentanyl 1-3 mg/kg slow IVP Administer midazolam 0.05 to 0.1 mg/kg slow IVP, 2.5-5 mg if the B/P is > 100 systolic Administer 1.5 mg/kg succinylcholine or 0.01 mg/kg vecuronium IVP As patient becomes relaxed, approximately 1-2 minutes after administration, intubate.
125	Rapid-Sequence Induction (cont.) Use primary and secondary ET tube placement confirmations Reassess patient’s vital signs Effects of the paralytic wear off in time If continued paralysis warranted, administer maintenance dose of the paralytic Assess patient for adequacy of sedation
126	Pharmacologically Assisted Intubation
127	Pharmacologically Assisted Intubation An alternative to RSI is the use of many of the same medications, without the use of paralytics. Medications can be reversed or are short acting. A disadvantage to this procedure occurs in the patient with trismus or a clenched jaw.
128	Pharmacologically Assisted Intubation (cont.) Preoxygenate with 100% O₂ for 5 minutes Establish IV with large-bore catheter Monitor ECG, SpO₂, waveform capnography, and vital signs Perform a thorough neurological exam Prepare for rapid administration of a sedative
129	Pharmacologically Assisted Intubation (cont.) Assemble and prepare ETT equipment Administer lidocaine 1.5 mg/kg IVP if head is injured or ICP is suspected Administer atropine 1.0 mg IVP if: Bradycardia is present Cervical-spine injury Patient is under age 16
130	Pharmacologically Assisted Intubation (cont.) Administer fentanyl 1-3 mg/kg slow IVP Administer midazolam 0.05 to 0.1 mg/kg slow IVP, 2.5-5 mg if the B/P is > 100 systolic Re-dose up to three times as needed As patient becomes relaxed, approximately 1-2 minutes after administration, intubate.
131	Pharmacologically Assisted Intubation (cont.) Use primary and secondary ET tube placement confirmations Reassess patient’s vital signs Assess patient for adequacy of sedation Re-sedate as needed
132	Summary