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Exogenous Surfactants |   |
Smoking Cessation Therapy
Approximately 10% cigarette smokers per year try to quit. By the end of one year only about 20% of those "would-be-quitters" have been successful. The problem is that cigarettes create both a psychological and physiological dependence, and both need to be treated with behavioral and pharmacological therapies for maximum success. For the latter, there are nicotine and nonnicotine replacements. They are most effective when combined with appropriate behavior modification therapy.
Nicotine replacements come in the form of gum, patches, pills, nasal spray, and inhalers. Nicotine polacrilex gum has been used the longest. Nicotine patches are available in 16 and 24 hour forms. The 16 hour patch was created to prevent excess nicotine release during sleep. The patches are available in 21 mg, 14 mg, and 7 mg doses for weaning. Nicotine nasal spray and inhalers are uncommon at this time (1997). The pills are fairly new, and there is little data on success rates.
Nonnicotine replacements consist of CLONIDINE and BUSPIRONE. The primary use for clonidine is for hypertension, but it also relieves withdrawal symptoms from nicotine and the opiates. It is available as tablets or patches in doses of 0.1 to 0.3 mg/day. Buspirone is an antianxiety drug from the benzodiazepine family. Early trials of buspirone for nicotine withdrawal are encouraging.
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Miscellaneous
Doxapram is a respiratory stimulant used for post-operative depression and alveolar hypoventilation syndromes. It stimulates peripheral chemoreceptors and brainstem respiratory centers. Dosage is 1-3 mg/mm by IV, up to a maximum of 600 mg. Doxapram can cause arrhythmias and hypertension by stimulating the release of epinephrine from the adrenals. It also can result in excessive CNS stimulation. Progesterone is also a respiratory stimulant. It is used for Pickwickian syndrome. Progesterone is administered sublingually for outpatients. Inpatients are given a bolus of 100 mg/day IM. Progesterone takes 2-3 weeks for maximum effects to develop. Naloxone is used to reverse ventilatory depression as a result of opiate administration (morphine, methadone, heroin). It is also effective in diazepam, propoxyphene, and ethanol overdoses. A bolusof 0.4-2.0 mg is given, but some patients may only require 0.1 mg/kg. Naloxone is short-acting so continuous infusion may be necessary. |
Muscle relaxants and sedatives are used to improve the balance between gas exchange and the rate of metabolism. Muscle relaxants (paralyzers) must be used in combination with adequate sedation. If not, patients become extremely frightened and possibly psychotic. Indications for their use are: shivering after bypass surgery, difficult intubations, and temporary control of the ventilator patient.
Pancuronium (Pavulon) is probably the most common paralyzer used. Intermittent bolus administration is recommended. If tachycardia develops from its use, Vercuronium should be substituted. Vercuronium can be given as a continuous infusion. Atracuronium can also be used, but is shorter-acting and can cause histamine release.
Agitation causes catecholamine release, can produce auto-PEEP in ventilator patients, and causes an imbalance between 02 delivery and 02 consumption. Sedatives prevent these adverse conditions from occurring. Haloperidol (Haldol) is the preferred sedative because of its lack of ventilatory depression or hypotension. It can cause cardiovascular depression if hypovolemia is present or if given with propranolol. A 3-5 mg bolus is given IV and if there is no response in 15-20 minutes the dose is doubled. Another option if there is no response is to add a Ben Zodiazepine (Valium, Ativan, Versed). However, these can cause ventilatory depression, and can result in rapid sedation and accumulate in the body.
Morphine Sulfate (MS) is used for vasodilation, CNS sedation, and has a mild inotrophic effect in patients with pulmonary edema. If the patient is not hypotensive, 5-10 mg of MS is given slowly via IV over several minutes. MS lowers pulmonary capillary pressure resulting in less leakage. Patient anxiety is also relieved. Ventilatory depression is possible but is rarely a problem.
Problems associated with MS are rapidly reversed with naloxone. One should avoid the use of MS as a sedative for asthmatic patients. MS (and other narcotics) cause histamine release and worsen asthma symptoms. Both oral and aerosolized MS have been used to increase exercise tolerance in the COPD patient. MS may reduce perceptions of dyspnea by acting directly on lung afferent nerves. This increases exercise capacity. An oral dose of 0.8 mg/kg or aerosol dose of 5 ml of a 1 mg/ml MS solution improve exercise endurance in these patients.
Propylene Glycol is a physiologically inert substance found in many aerosol preparations. It is used as a solvent and stabilizing agent. It is hygroscopic and used to minimize shrinkage of aerosol particles as they travel through the respiratory tract.
Pulmonary hypertension is defined as a mean pulmonary artery pressure >25 mm Hg at rest or >30 mm Hg with exercise. Most cases of pulmonary hypertension are secondary, meaning they are a result of another process. For example, hypoxia causes pulmonary vasoconstriction and therefore hypertension. Treatment for these causes of hypertension consist of fixing the primary problem, rather than treating the hypertension. "Primary" pulmonary hypertension is not a result of another problem. It is treated with a vasodilator or anticoagulants.
Primary pulmonary hypertension (PPH) usually develops in the third or fourth decade of life. Without treatment, most patients die within 2-3 years. PPH is a result of pulmonary capillary lumen cellular proliferation, thrombi, or fibrosis. Warfarin and Heparin have been used for anticoagulation and to prevent further thrombi. Vasodilators are effective for some patients, but not all. However, those who respond initially have a favorable response over the long term. Epoprostenol is given to test the patient's response. If favorable, continue its use. The alternative is heart-lung or single lung transplantation.