Tobacco use is a common history finding that increases the likelihood of COPD, congestive heart failure, and pulmonary embolism. Orthopnea, paroxysmal nocturnal dyspnea, and edema suggest a possible diagnosis of congestive heart failure. Pleuritic quality chest pain may indicate pericarditis, pulmonary embolism, pneumothorax, or pneumonia. A severe sore throat could indicate epiglottitis. The presence of cough may indicate the presence of asthma, chronic obstructive pulmonary disease (COPD), or pneumonia. Key components of history include onset, duration, aggravating factors, and alleviating factors. The history and physical exam should ascertain whether there are any chronic underlying cardiovascular or pulmonary illnesses. The signal is then sent to the primary muscles of respiration, the diaphragm, external intercostals, and scalene muscles along with other minor muscles of respiration. However, the rate of respiration is modified by allowing for aggregated sensory input from the peripheral sensory system, which monitors oxygenation, and the central sensory system, which monitors pH and indirectly carbon dioxide levels along with several other portions of the cerebellar brain modulate to create a unified neural signal. Respiratory centers located within the medulla oblongata and pons of the brainstem are responsible for generating the baseline respiratory rhythm. When pH rises to more alkalotic levels, hypoventilation occurs, and carbon dioxide levels increase secondary to decreased ventilation. As these areas become more acidic, sensory input is generated to stimulate hyperventilation, and carbon dioxide within the body is reduced through increased ventilation. Chemoreceptors responsive to pH change are located on the ventral surface of the medulla. This characteristic proves to be useful in that rapid changes in pH within the cerebrospinal fluid are possible. Carbon dioxide is a lipid-soluble molecule that freely diffuses across the blood-brain barrier. pH changes within the brain, and surrounding cerebrospinal fluid is derived primarily from increases or decreases in carbon dioxide levels. Prime locations within the brain include the ventral surface of the medulla and the retrotrapezoid nucleus. They function by sensing pH changes in the CNS. Ĭentral chemoreceptors manage the majority of control over the respiratory drive. It has been postulated that the carotid bodies comprise 15% of the total driving force of respiration.

Once stimulated by hypoxia, carotid and aortic bodies send a signal via the ninth cranial nerve (the glossopharyngeal nerve) to the nucleus tractus solitarius in the brain, which then, stimulates excitatory neurons to increase the rate of ventilation. However, hypercapnia and acidosis enhance the sensitivity of these sensors and play a partial role in the functioning of receptors. Both receptors function to monitor the partial pressure of oxygen in the arterial blood. Peripheral chemoreceptors comprise the carotid and aortic bodies. Both kinds of mechanoreceptors signal through the tenth cranial nerve to the brain to escalate the rate of breathing, the volume of breaths, or to stimulate coughing patterns of breathing because of irritants present in the airway. However, the rapid-acting receptors respond to both the volume of the lungs and chemical triggers, such as foreign agents that may be harmful.

Slow-acting spindle sensors convey only volume information. There are two primary types of thoracic sensors: slow adapting stretch spindles and rapid adapting irritant receptors. Sensory information to the respiratory center regarding the volume of the lung space is provided by mechanoreceptors located in the airways, trachea, lung, and pulmonary vessels. Each of these groups communicates with one another to unify the efforts as the pace-making potential of respiration. The pontine groupings play their part in modulating the intensity and frequency of the medullary signals where the pneumotaxic groups limit inhalation, and the apneustic centers prolong and encourage inhalation. Inhalation is managed by the dorsal group, and the ventral medulla accounts for exhalation. The pontine grouping further classifies into the pneumotaxic and apneustic centers. The respiratory center is comprised of three neuron groupings in the brain: the dorsal and ventral medullary groups and the pontine grouping. It results from multiple signal interactions with receptors in the central nervous system (CNS), peripheral chemoreceptors, and mechanoreceptors in the respiratory tract and chest wall.

Dyspnea on exertion is the sensation of running out of the air and of not being able to breathe fast or deeply enough during physical activity.

Pulmonary embolism lung sounds