Respiratory Emergencies

The physiology refresher

Inspiration is an active process. The diaphragm contracts and drops down while the intercostal muscles expand the chest wall, so the chest cavity gets bigger. As the cavity enlarges the pressure inside it drops, and air is pulled in. Expiration is passive: the diaphragm and intercostals relax, the chest cavity shrinks, the pressure rises, and air is pushed out.

Pediatric anatomy changes this picture in two ways. The rib cage of an infant or child flares outward at the bottom, which makes the diaphragm flatter and less able to move well, and the chest wall is more flexible and floppy. Adults compensate for respiratory trouble by using more chest muscle and taking deeper breaths; children compensate mainly by increasing their rate, which burns through their energy much faster.

Adequate vs. inadequate breathing

The first decision with any patient who is short of breath is whether their breathing is adequate. The table below compares adequate and inadequate breathing across six findings.

Table 19.1Adequate vs. inadequate breathing

Rate alone never tells the whole story. A fast rate from crying, exertion or anxiety can still be adequate. What matters is whether the rate is packaged with other findings such as altered mental status, cyanosis or a low SpO2.

Recognizing inadequate breathing

The brain has zero oxygen reserve, so a change in mental status is often the first sign of inadequate breathing. The patient becomes anxious and may describe a sense of "impending doom"; that gives way to confusion, combativeness or lethargy, and finally to unconsciousness. Cyanosis appears first around the eyes and in the nail beds, and it is a profound warning sign of severe hypoxia.

Other signs show that compensation is failing. Respirations that slow or become irregular mean the patient can no longer keep up. The patient may be unable to speak normally and cannot get more than 1–2 words out at a time. A silent chest is one in which air movement is so diminished that you hear nothing, even though the chest may still be moving. The SpO2 stays low despite supplemental oxygen. Agonal respirations, which are sporadic, gasping breaths at only a few per minute, come just before respiratory arrest.

In children, the specific signs of inadequate breathing are nasal flaring, grunting, seesaw breathing and retractions. Bradycardia in a pediatric respiratory patient is never normal. It warns of imminent cardiac arrest, because respiratory failure is the leading cause of cardiac arrest in children. Early hypoxia speeds a child's heart up just as it does an adult's; the slowing comes late, when compensation is failing.

Treating inadequate breathing

Treatment follows from the assessment. The table below matches each level of breathing to its signs and the intervention it calls for.

Table 19.2Treating inadequate breathing

A nonrebreather mask requires the patient to be breathing adequately. It provides no ventilation to an apneic patient; that patient needs a BVM. If you are uncertain whether breathing is inadequate, ventilate anyway. Err toward action.

Never hyperventilate the patient. Eliminating too much CO2 constricts the cerebral blood vessels and reduces perfusion of the brain. In an infant or child, a low or bradycardic pulse during ventilation means real trouble: recheck the airway positioning, the chest rise and the oxygen supply and tubing.

Assessing the patient with breathing difficulty

Breathing difficulty is a subjective complaint, so assess the patient rather than relying on the patient's report alone. The primary assessment comes first. Then take the history, using OPQRST adapted to the complaint (onset, provocation, quality and cough, radiation, severity and time) together with SAMPLE.

In the physical exam, look for altered mental status, a barrel chest and the tripod position. Note retractions, accessory muscle use, flared nostrils and pursed lips, and count how many words the patient can say at a time, down to "one-word dyspnea." Assess skin color, look for pedal and sacral edema, listen for noisy breathing, and note an SpO2 below 95%.

If the pulse oximeter is ready, place the sensor before you apply oxygen so that you have a true room-air baseline. Never delay oxygen just to get a reading.

Lung sound auscultation

Auscultation of the lungs tells you where in the airway the problem lies. The table below gives each abnormal sound, when in the cycle it is heard, what causes it and the conditions it goes with.

Table 19.3Lung sound auscultation

A worsening patient can lose their wheezes entirely. That is not improvement. It means the patient has stopped moving enough air to generate the sound.

CPAP

Continuous positive airway pressure (CPAP) delivers noninvasive positive pressure together with supplemental oxygen (O2) through a sealed mask. The pressure is not enough to substitute for artificial ventilation. Its benefit comes from positive end-expiratory pressure (PEEP), which keeps the small airways and alveoli from collapsing at the end of each breath; the typical range is 5–15 cm H2O.

CPAP is indicated for pulmonary edema and drowning, for asthma and COPD, and as a bridge in respiratory failure. In every case the patient must still be breathing on their own.

The contraindications follow from what the device needs in order to work. It is contraindicated in a patient with a depressed mental status or no spontaneous respiratory rate, a patient who cannot sit up, a patient who is hypotensive with a systolic below 90, a patient who cannot maintain a mask seal, and a patient with nausea or vomiting. It is also contraindicated in chest trauma or suspected pneumothorax, in shock, and in an upper GI bleed or recent gastric surgery.

CPAP has side effects of its own. It reduces venous return, which can drop the blood pressure (BP); it carries a risk of pneumothorax in lungs that are already fragile; it can cause gastric distention with vomiting and the risk of aspiration; and it dries the corneas. Reassess constantly. If the patient's mental status or breathing worsens, remove the CPAP and go to BVM ventilation.

The specific conditions

The conditions that cause breathing difficulty each have a mechanism, a set of key signs and something particular you need to know. The table below sets them out.

Table 19.4The specific conditions

Medications — inhalers & nebulizers

Assisting with a metered-dose inhaler (MDI) requires medical direction. The patient exhales, places the mouthpiece past the teeth and above the tongue, presses the canister while inhaling slowly, and holds the breath for 5–10 seconds. A spacer makes the timing less critical. Wait 15–30 seconds between doses.

Inhalers fall into two groups. Rescue inhalers, such as albuterol, levalbuterol and Combivent, are for acute attacks. Maintenance inhalers, such as beclomethasone, Flovent and Advair, are for daily control and are never used for an acute attack.

A small-volume nebulizer (SVN) delivers medication as a continuous vapor over several minutes. The table below gives the medications used in it.

Table 19.5Medications — inhalers & nebulizers

Albuterol is a bronchodilator that works by stimulating beta receptors; it is fast-acting and usually first-line. Ipratropium bromide is a bronchodilator that works by blocking parasympathetic bronchoconstriction; its onset is slower and its duration longer. DuoNeb combines the two and is a first-line combination option.

The side effects of nebulized medication mirror those of inhalers: an increased pulse, tremors and jitteriness. A patient with inadequate breathing will not benefit from a nebulizer, because the patient is not breathing deeply enough to pull in the medication.