Carbon dioxide partial pressure (PaCO₂)
The partial pressure of carbon dioxide in the arterial blood.

Chronic Bronchitis
An obstructive lung disease where chronic airway inflammation is present with an abnormally large amount of secretions produced. A person will be diagnosed with chronic bronchitis if he or she coughs up secretions on most days for at least 3 months of the year; for at least 2 consecutive years. Because the secretions block the airways, it blocks oxygen from getting into your blood stream. The respiratory muscles have to work harder to get air in and out of the lungs.

Chronic Obstructive Pulmonary Disease (COPD)
This diagnosis is often used as a catch–all phrase to include emphysema, chronic bronchitis and asthma. An individual may have only one component or a portion of all three states.  For further information, see asthma, chronic bronchitis, emphysema, and the What–Is–COPD? in the What–Is section.

Cognition
Awareness, one of the three aspects of the mind, the others being affection (feeling or emotion), and conation (willing or desiring). They may work as a whole, but any one may dominate any mental process.

Coma
Complete loss of consciousness.

Comatose
In a state of coma.

Compliance
A measure of the stiffness of the lung. A less compliant lung (stiffer) requires higher inspiratory pressures to maintain ventilation. Technically, compliance describes the elastic properties of the lung measured as change in volume divided by change in pressure. Thus, the greater the compliance the larger the delivered volume can be per unit of pressure. Lung compliance is measured in mL/cm of H₂O.

Conation
One of the three aspects of the mind, in particular dealing with "willing and desiring", the others being cognition (awareness) and affection (feeling or emotion).  They may work as a whole, but any one may dominate any mental process.

Constant (or continuous) positive airway pressure (CPAP)
A non–invasive ventilation   assistance technique, lesser level than full mechanical ventilation; constant, low level pressure delivered to the lungs during spontaneous ventilation (i.e. off a ventilator), usually through a face mask or nasal prongs. CPAP is useful in mild lung diseases, sleep apnea, or during the end stages of recovery of more severe diseases.  See What–is–Ventilation in our What–Is section for fuller and further discussion and information concerning ventilation.

Cor Pumonale
Is defined as right sided heart failure. Blood is returned to the right side of the heart low in oxygen and is pumped up to the lungs to replenish the oxygen supply. In lung disease, there may be high pressure in the lungs, making it difficult to pump against. After time, the right ventricle of the heart may balloon out and become ineffective. The blood could back up in the system and swelling make be noted in the ankles.

Corticosteroids
Hormones which are steroids and produced by the adrenal cortex and are also produced exogenous (artificially from external sources).  ARDS is an inflammatory process and administration of steroids (drugs) may suppress the inappropriate inflammatory mechanisms occurring in ARDS.   A number of studies have shown administration in early stage of sepsis and ARDS results in no appreciable benefits.  Stronger evidence exists that use in the late stages of ARDS.  For further information and discussion, see Respiratory Conference Summaries - 29th Educational And Scientific Symposium Of The Society Of Critical Care Medicine

Orlando, FL, February 11-15, 2000 Release date: April 10, 2000
Authors: Howard L. Corwin, MD, Neil R. MacIntyre, MD
The latest advances in selected topics in critical care including topics dealing with treatment and management of ARDS cases.

Medscape, 2000. © 2000 Medscape, Inc.; on-line web address for article at Medscape: http://respiratorycare.medscape.com/19966.rhtml