acute
[ah-kūt´] 1. sharp.
2. having severe symptoms and a short course. Some serious illnesses that were formerly considered acute (such as myocardial infarction) are now recognized to be acute episodes of chronic conditions.
acute respiratory distress syndrome (ARDS) a group of symptoms accompanying fulminant pulmonary edema and resulting in acute respiratory failure; called also
shock lung, wet lung, and many other names descriptive of etiology or clinical manifestations. Many etiologic factors have been associated with ARDS, including shock, fat embolism, fluid overload, oxygen toxicity, fluid aspiration, narcotic overdose, disseminated intravascular coagulation, multiple transfusions, inhalation of toxic gases, diffuse pulmonary infection, and systemic reactions to sepsis, pancreatitis, and massive trauma or burns.
ARDS is characterized clinically by
dyspnea,
tachypnea,
tachycardia,
cyanosis, and
hypoxemia. Pa
O2/FI
O2 remains low (below 2 cc) even with oxygen therapy at high oxygen concentrations. The lung compliance is decreased so that the lung is stiffer and more difficult to ventilate. Chest radiographs show signs of bilateral interstitial and alveolar edema. Cardiac filling pressures are normal, and the pulmonary capillary wedge pressure is below 18 torr.
Most authorities consider that the syndrome has three phases or stages that characterize its progression: the
exudative stage, the
fibroproliferative or
proliferative stage, and the
resolution or
recovery stage. The exudative stage comes first, two to four days after onset of lung injury, and is distinguished by the accumulation of excessive fluid in the alveoli with entrance of protein and inflammatory cells from the alveolar capillaries into the air spaces. The fibroproliferative stage comes second and is characterized by an increase in connective tissue and other structural elements in the lungs in response to the initial injury. It begins between the first and third weeks after the initial injury and may last up to ten weeks. Microscopic examination reveals lung tissue that appears densely cellular. The patient is at risk for
pneumonia,
sepsis, and
pneumothorax at this time. The third stage is the resolution or recovery stage. During this stage the lung reorganizes and recovers, although it continues to show signs of
fibrosis. Lung function may continue to improve for as long as six to twelve months or even longer, depending on the precipitating condition and severity of the injury. It is important to remember that there are often different levels of pulmonary recovery in patients with ARDS.
Some authorities refer to a fourth phase or stage of ARDS, the period after the resolution or recovery stage. Some patients continue to experience health problems caused by the acute illness, such as coughing, limited exercise tolerance, and fatigue. Anxiety, depression, and flashback memories of the critical illness may also occur and be similar to
posttraumatic stress disorder.
Treatment and Patient Care. Mechanical
ventilation must be begun at the first signs of
hyperventilation and
hypoxemia, before obvious signs of respiratory distress develop. A cuffed
endotracheal tube or
tracheostomy tube is used to maintain an airway. The patient is ventilated at the lowest oxygen concentration that maintains the arterial oxygen saturation (Sa
O2) at 90 per cent.
positive end-expiratory pressure (PEEP) or
continuous positive airway pressure (CPAP) may be used to increase the number of alveoli that remain open at the end of exhalation and thus decrease pulmonary shunt.
hemodynamic monitoring, using a
swan-ganz catheter, is done to measure cardiac output, pulmonary capillary wedge pressure, and right atrial wedge pressure. An arterial line is placed to continuously monitor
blood pressure and measure arterial
blood gases. A diuretic such as
furosemide (Lasix) may be administered to reduce fluid volume overload and pulmonary edema. If infection develops, antibiotics are administered. Hemodynamic parameters, arterial blood gas levels, intake and output, breath sounds, vital signs, inspiratory pressure, tidal volume, inspired oxygen concentration, and end-expiratory pressure are all continuously monitored.
acute stress disorder an
anxiety disorder characterized by development of
anxiety,
dissociation, and other symptoms within one month following exposure to an extremely traumatic event, the symptoms including reexperiencing the event, avoidance of trauma-related stimuli, anxiety or increased arousal, and some or all of the following: a subjective sense of diminished emotional responsiveness, numbing, or detachment, derealization, depersonalization, and amnesia for aspects of the event. If persistent, it may become
posttraumatic stress disorder.
respiratory
[res´pir-ah-tor″e] pertaining to respiration.
acute respiratory distress syndrome (
adult respiratory distress syndrome) a group of symptoms accompanying fulminant pulmonary edema and resulting in acute respiratory failure; see also
acute respiratory distress syndrome.
respiratory care 1. the health care profession providing, under qualified supervision, diagnostic evaluation, therapy, monitoring, and rehabilitation of patients with cardiopulmonary disorders; it also employs educational activities to support patients and their families and to promote cardiovascular health among the general public.
2. the care provided by members of this profession.
3. the diagnostic and therapeutic use of medical gases and their administering apparatus, environmental control systems, humidification, aerosols, medications, ventilatory support, bronchopulmonary drainage, pulmonary rehabilitation, cardiopulmonary resuscitation, and airway management.
respiratory distress syndrome, neonatal (
respiratory distress syndrome of the newborn (RDS)) a condition of the newborn marked by dyspnea with cyanosis, heralded by such prodromal signs as dilatation of the nares, grunting on exhalation, and retraction of the suprasternal notch or costal margins. It usually occurs in newborns who are preterm, have diabetic mothers, or were delivered by cesarean section; sometimes there is no apparent predisposing cause.
This is the major cause of death in neonates and survivors have a high risk for chronic neurologic complications. No one factor is known to cause the condition; however, prematurity and interrupted development of the
surfactant system is thought to be the major causative factor. Surfactant is secreted by the epithelial cells of the alveoli. It acts as a detergent, decreasing the surface tension of fluids that line the alveoli and bronchioles and allowing for uniform expansion of the lung and maintenance of lung expansion. When there is an inadequate amount of surfactant, a great deal of effort is required to re-expand the alveoli with air; thus the newborn must struggle for each breath. Insufficient expansion of the alveoli results in partial or complete collapse of the lung (
atelectasis). This in turn produces hypoxemia and elevated serum carbon dioxide levels.
The hypoxemia causes metabolic acidosis from increased production of lactic acid and respiratory acidosis due to the hypercapnia. The lowered pH constricts pulmonary blood vessels and inhibits intake of oxygen, thus producing more hypoxemia and interfering with the transport of substances necessary for the production of the sorely needed surfactant.
Patient Care. In order to minimize the hazards of oxygen toxicity and
retinopathy of prematurity, the blood gases of the newborn with respiratory distress syndrome must be carefully monitored to assess response to therapy. The goal is to administer only as much oxygen as is necessary to maintain an optimal level of oxygenation.
To improve respiratory function, intubation, suctioning of the air passages, and
continuous positive airway pressure via nasal prongs are commonly used, as well as instillation of artificial
surfactant. Monitoring is conducted using
transcutaneous oxygen monitoring or a
pulse oximeter. To optimize breathing effort and facilitate air exchange, the newborn is positioned on the back with a shoulder support to keep the neck slightly extended, or on the side with the head supported. Because of the drying effect of oxygen therapy and the prohibition of oral fluids, mouth care must be given frequently to prevent drying and cracking of the lips and oral mucosa.
respiratory failure a life-threatening condition in which respiratory function is inadequate to maintain the body's need for oxygen supply and carbon dioxide removal while at rest; it usually occurs when a patient with
chronic airflow limitation develops an infection or otherwise suffers an additional strain on already seriously impaired respiratory functions. Inadequate or unsuccessful treatment of
respiratory insufficiency from a variety of causes can lead to respiratory failure. Called also
ventilatory failure.
Early symptoms include dyspnea, wheezing, and apprehension; cyanosis is rarely present. As the condition worsens the patient becomes drowsy and mentally confused and may slip into a coma.
blood gas analysis is an important tool in diagnosing respiratory failure and assessing effectiveness of treatment. The condition is a medical emergency that can rapidly progress to irreversible cardiopulmonary failure and death. Treatment is concerned with improving ventilation and oxygenation of tissues, restoring and maintaining
fluid balance and
acid-base balance, and stabilizing cardiac function.
respiratory insufficiency a condition in which respiratory function is inadequate to meet the body's needs when increased physical activity places extra demands on it. Insufficiency occurs as a result of progressive degenerative changes in the alveolar structure and the capillary tissues in the pulmonary bed, as, for example, in
chronic airflow limitation and
pulmonary fibrosis. Treatment is essentially supportive and symptomatic. If the condition is not successfully managed it may progress to
respiratory failure.
respiratory therapist a health care professional skilled in the treatment and management of patients with respiratory problems, who administers
respiratory care. The minimum educational requirement is an associate degree, providing knowledge of anatomy, physiology, pharmacology, and medicine sufficient to serve as a supervisor and consultant. Those registered by the National Board for Respiratory Therapy are designated Registered Respiratory Therapist (RRT).
respiratory therapy technician a health care professional who has completed a specialized one- or two-year educational program and who performs routine care, management, and treatment of patients with respiratory problems under the supervision of a
respiratory therapist. Such programs are usually found in community colleges and are accredited by the Joint Review Committee for Respiratory Therapy Education.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.