What is irregular breathing pattern called?

DEFINITIONS

Patterns of breathing during sleep may be categorized into one of several types. Primary snoring [PS] consists of snoring without a change in sleep architecture, alveolar ventilation, or gas exchange abnormalities. The incidence of PS on a habitual basis ranges from 7% to 10% of children.3 Most children with PS do not progress to SDB.4

Upper airway resistance syndrome [UARS] describes the effect of negative intrathoracic pressure changes on inspiration during sleep. These changes are caused by airway obstruction that may lead to electroencephalographic arousals and major sleep fragmentation, but not to frank apnea. In addition to the repeated transient electroencephalographic arousals, an increase in snoring occurs just prior to the arousal. Changes in the respiratory pattern include an increase in the time of inspiration and a coinciding decrease in the time of expiration, but no change in gas exchange abnormalities.5 UARS is found most often during rapid eye movement [REM] sleep. It is difficult to document in children because it usually requires direct measurement of intrathoracic pressure in the esophagus, a procedure difficult to perform in most children. In assessing the quality of life in children with SDB, de Serres and associates have shown that UARS is more common than obstructive apnea.6

Obstructive apnea [OA] is the absence of any gas exchange that results from complete obstruction of the upper airway during a respiratory effort. During sleep, these obstructive episodes result in electroencephalographic arousals, sleep fragmentation, and gas exchange abnormalities.

During an episode of central apnea, there is an absence of gas exchange that results from an absence of a respiratory effort. Episodes of central apnea are abnormal if they are longer than 20 seconds in duration or associated with one of the following: oxygen desaturation below 90%, bradycardia, or nighttime arousals.7,8 Mixed apnea episodes contain both obstructive and central elements.

Hypopnea is a partial obstruction during sleep that may result in electroencephalographic arousal, sleep fragmentation, and changes in ventilation and gas exchange. In children, there has been a lack of consensus of what actually constitutes a hypopnea. Catterall and colleagues have described a hypopnea as breath with a 50% reduction in airflow.9 Gould and co-workers have described it as a 50% reduction in respiratory effort.10 Guilleminault and associates have reported both a reduction in airflow and associated oxygen desaturation.11 Block and colleagues have suggested a reduction in airflow and respiratory effort in association with a fall in oxygen saturation.12 Complete [obstructive apneas] and partial obstructions [hypopneas] intermingled with periods of normal sleep and ventilation are defined as the obstructive sleep apnea syndrome [OSAS].

A respiratory event–related arousal [RERA] is a gradual increase in the end-inspiratory negative intrathoracic pressure of at least 5 cm H2O during five or more breath cycles, followed by an arousal or awakening.13 This subtle measure of a significant respiratory disturbance may be more important in children than in adults.

Observation of Breathing Patterns

Breathing patterns vary among individuals and may be influenced by pain, emotion, body temperature, sleep, body position, activity level, and the presence of pulmonary, cardiac, metabolic, or nervous system disease [Table 4-4]. The optimal time, clinically, to examine a patient's breathing pattern is when he or she is unaware of the inspection because knowledge of the physical examination can influence the patient's respiratory pattern.

Observation of breathing pattern should include an assessment of rate [12 to 20 breaths per minute is normal], depth, ratio of inspiration to expiration [one to two is normal], sequence of chest wall movement during inspiration and expiration, comfort, presence accessory muscle use, and symmetry.

 Clinical Tip

If possible, examine a patient's breathing pattern when he or she is unaware of the inspection because knowledge of the physical examination can influence the patient's respiratory pattern. Objective observations of ventilation rate may not always be consistent with a patient's subjective complaints of dyspnea. For example, a patient may complain of shortness of breath but have a ventilation rate within normal limits. Therefore the patient's subjective complaints, rather than the objective observations, may be a more accurate measure of treatment intensity.

7 How can the respiratory pattern and brainstem reflexes help in the assessment of the comatose patient?

Respiratory pattern and rate are often helpful in identifying the cause of coma. Hyperventilation, as an example, may be a response to hypoxemia, metabolic acidosis, toxins, or dysfunction within the pons. Cheyne-Stokes breathing may indicate diencephalic lesions or bilateral cerebral hemisphere dysfunction, for example, increased ICP or metabolic abnormalities. Cluster breathing is associated with high medulla or lower pontine lesions. Brainstem reflexes should be examined and focal motor abnormalities, as well as reflex asymmetry, recorded. Equal and reactive pupils may indicate toxic or metabolic causes, whereas a unilateral fixed and dilated pupil usually indicates oculomotor palsy possibly as a result of uncal herniation. Bilateral pinpoint pupils with minute reaction suggest a pontine lesion, and bilateral fixed and dilated pupils may indicate medullary injury, global anoxia, or hypothermia. Ocular bobbing [a repetitive rapid vertical deviation downward and slow return to neutral position] indicates a pontine lesion often seen in basilar artery occlusion, whereas ping-pong or windshield-wiper eye movements usually indicate bilateral cerebral dysfunction. Eye movements can safely be elicited in the comatose patient without cervical spine injury by performing the oculocephalic maneuver [often called “doll's eyes”], that is, by rapidly rotating the head from side to side. If the paramedian pontine reticular formation and the vestibular system are intact, the eyes should move smoothly in the direction opposite to that in which the head is rotated.

If cervical spine stability is in question, or no response to oculocephalic maneuvers occurs, the oculovestibular response [often called “cold calorics”] can be tested instead. One tympanic membrane is irrigated with 30 mL of ice-cold water and the response observed. When the underlying brainstem structures are intact, both eyes will deviate laterally toward the side where the cold water is instilled. If cortical structures and parts of the frontal lobe are intact, there will be nystagmus with the fast phase toward the nonirrigated ear. In metabolic or toxic coma the clinician usually sees intact gaze deviation toward the irrigated ear but absent or abnormal nystagmus indicating cortical dysfunction. In many comatose patients with structural brainstem injury, the oculovestibular system is impaired, and deviation of the eyes is absent or abnormal.

Physical Examination

Pattern of breathing [e.g., splinting, use of pursed lips or accessory muscles], body habitus [e.g., cachexia, obesity], posture [e.g., leaning forward on elbows to recruit pectoralis muscles as ventilatory muscles, as in COPD], skeletal deformity, and emotional state may be important clues to the underlying diagnosis. Cough on deep inspiration or expiration suggests asthma or interstitial lung disease. A generalized decrease in the intensity of breath sounds suggests emphysema or moderate to severe bronchoconstriction, whereas a localized decrease may result from pneumothorax, pleural effusion, localized airway obstruction, or elevated hemidiaphragm of any cause. Forced expiratory maneuvers may elicit focal or diffuse wheezing. Cardiac examination may suggest pulmonary hypertension [e.g., right ventricular heave or prominent P2] or right ventricular failure [e.g., jugular venous distention, right-sided S3 gallop]. Clubbing of the digits is an easily overlooked sign of many processes, notably cancer or purulent lung disease [e.g., bronchiectasis]. Cyanosis, a bluish coloration of the perioral region or nails, indicates there are at least 5 g of deoxygenated hemoglobin per 100 mL of blood [note: hypoxemia in the presence of significant anemia may not cause cyanosis because of insufficient hemoglobin]. Edema of the lower extremities suggests congestive heart failure if symmetrical and thromboembolic disease if asymmetrical. Assessment of the patient's emotional status may be helpful.84

If a patient's history includes a report that he or she develops dyspnea walking a short distance [e.g.,