Respiratory arrest and cardiac arrest Cardiac Arrest Cardiac arrest is the cessation of cardiac mechanical activity resulting in the absence of circulating blood flow. Cardiac arrest stops blood from flowing to vital organs, depriving them of... read more are distinct, but inevitably if untreated, one leads to the other. (See also Respiratory Failure Overview of Respiratory Failure Acute respiratory failure is a life-threatening impairment of oxygenation, carbon dioxide elimination, or both. Respiratory failure may occur because of impaired gas exchange, decreased ventilation... read more , Dyspnea Dyspnea Dyspnea is unpleasant or uncomfortable breathing. It is experienced and described differently by patients depending on the cause. Although dyspnea is a relatively common problem, the pathophysiology... read more , and Hypoxia Acute Hypoxemic Respiratory Failure (AHRF, ARDS) Acute hypoxemic respiratory failure is defined as severe hypoxemia (PaO2 (See also Overview of Mechanical Ventilation.) Airspace filling in acute hypoxemic respiratory failure (AHRF) may result... read more .)
Interruption of pulmonary gas exchange for > 5 minutes may irreversibly damage vital organs, especially the brain. Cardiac arrest almost always follows unless respiratory function is rapidly restored. However, aggressive ventilation may also have negative hemodynamic consequences, particularly in the periarrest period and in other circumstances when cardiac output is low. In most cases, the ultimate goal is to restore adequate ventilation and oxygenation without further compromising a tentative cardiovascular situation.
Etiology of Respiratory Arrest
Respiratory arrest (and impaired respiration that can progress to respiratory arrest) can be caused by
Decreased respiratory effort
Respiratory muscle weakness
Obstruction may involve the
Upper airway obstruction may occur in infants < 3 months, who are usually nose breathers and thus may have upper airway obstruction secondary to nasal blockage. At all ages, loss of muscular tone with decreased consciousness may cause upper airway obstruction as the posterior portion of the tongue displaces into the oropharynx. Other causes of upper airway obstruction include blood, mucus, vomitus, or foreign body; spasm or edema of the vocal cords; and pharyngolaryngeal tracheal inflammation (eg, epiglottitis Epiglottitis Epiglottitis is a rapidly progressive bacterial infection of the epiglottis and surrounding tissues that may lead to sudden respiratory obstruction and death. Symptoms include severe sore throat... read more , croup Croup Croup is acute inflammation of the upper and lower respiratory tracts most commonly caused by parainfluenza virus type 1 infection. It is characterized by a brassy, barking cough and inspiratory... read more ), tumor, or trauma. Patients with congenital developmental disorders (eg, Down syndrome Down Syndrome (Trisomy 21) Down syndrome is an anomaly of chromosome 21 that can cause intellectual disability, microcephaly, short stature, and characteristic facies. Diagnosis is suggested by physical anomalies and... read more , laryngeal disorders Overview of Laryngeal Disorders The larynx contains the vocal cords and serves as the opening to the tracheobronchial tree. Laryngeal disorders include Benign laryngeal tumors Contact ulcers Laryngitis Laryngoceles read more , congenital jaw abnormalities Congenital Jaw Abnormalities The jaw can be missing, deformed, or incompletely developed at birth. (See also Introduction to Congenital Craniofacial and Musculoskeletal Disorders and Overview of Congenital Craniofacial... read more ) often have abnormal upper airways that are more easily obstructed.
Lower airway obstruction may result from aspiration, bronchospasm, airspace filling disorders (eg, pneumonia Overview of Pneumonia Pneumonia is acute inflammation of the lungs caused by infection. Initial diagnosis is usually based on chest x-ray and clinical findings. Causes, symptoms, treatment, preventive measures, and... read more , pulmonary edema Pulmonary Edema Pulmonary edema is acute, severe left ventricular failure with pulmonary venous hypertension and alveolar flooding. Findings are severe dyspnea, diaphoresis, wheezing, and sometimes blood-tinged... read more , pulmonary hemorrhage), or drowning Drowning Drowning is respiratory impairment resulting from submersion in a liquid medium. It can be nonfatal (previously called near drowning) or fatal. Drowning results in hypoxia, which can damage... read more .
Decreased respiratory effort
Decreased respiratory effort reflects central nervous system (CNS) impairment due to one of the following:
Central nervous system disorder
Adverse drug effect
Central nervous system disorders that affect the brain stem (eg, stroke Overview of Stroke Strokes are a heterogeneous group of disorders involving sudden, focal interruption of cerebral blood flow that causes neurologic deficit. Strokes can be Ischemic (80%), typically resulting... read more , infection, tumor) can cause hypoventilation. Disorders that increase intracranial pressure usually cause hyperventilation initially, but hypoventilation may develop if the brain stem is compressed.
Drugs that decrease respiratory effort include opioids and sedative-hypnotics (eg, barbiturates, alcohol; less commonly, benzodiazepines). Combinations of these drugs further increase the risk of respiratory depression ( 1 Etiology references Respiratory arrest and cardiac arrest are distinct, but inevitably if untreated, one leads to the other. (See also Respiratory Failure, Dyspnea, and Hypoxia.) Interruption of pulmonary gas exchange... read more ). Usually, an overdose (iatrogenic, intentional, or unintentional) is involved, although a lower dose may decrease effort in patients who are more sensitive to the effects of these drugs (eg, older patients, deconditioned patients, patients with chronic respiratory insufficiency or obstructive sleep apnea). The risk for opioid-induced respiratory depression (ORID) is most common in the immediate postoperative recovery period but persists throughout a hospital stay and beyond. OIRD can lead to catastrophic outcomes such as severe brain damage or death. ( 2 Etiology references Respiratory arrest and cardiac arrest are distinct, but inevitably if untreated, one leads to the other. (See also Respiratory Failure, Dyspnea, and Hypoxia.) Interruption of pulmonary gas exchange... read more )
Gabapentinoids (gabapentin, pregabalin) may cause serious breathing difficulties in patients using opioids and other drugs that depress the CNS, older patients, or patients who have underlying respiratory impairment such as patients with chronic obstructive pulmonary disease Chronic Obstructive Pulmonary Disease (COPD) Chronic obstructive pulmonary disease (COPD) is airflow limitation caused by an inflammatory response to inhaled toxins, often cigarette smoke. Alpha-1 antitrypsin deficiency and various occupational... read more (COPD).
Metabolic disorders that cause CNS depression due to severe hypoglycemia or hypotension ultimately compromise respiratory effort.
Respiratory muscle weakness
Weakness may be caused by
Respiratory muscle fatigue
Respiratory muscle fatigue can occur if patients breathe for extended periods at a minute ventilation exceeding about 70% of their maximum voluntary ventilation (eg, because of severe metabolic acidosis Metabolic Acidosis Metabolic acidosis is primary reduction in bicarbonate (HCO3−), typically with compensatory reduction in carbon dioxide partial pressure (Pco2); pH may be markedly low or slightly... read more or hypoxemia).
Neuromuscular causes include spinal cord injury, neuromuscular diseases (eg, myasthenia gravis Myasthenia Gravis Myasthenia gravis is characterized by episodic muscle weakness and easy fatigability caused by autoantibody- and cell-mediated destruction of acetylcholine receptors. It is more common among... read more , botulism Botulism Botulism is poisoning that is due to Clostridium botulinum toxin and that affects the peripheral nerves. Botulism may occur without infection if toxin is ingested, injected, or inhaled... read more , poliomyelitis Poliomyelitis Poliomyelitis is an acute infection caused by a poliovirus (an enterovirus). Manifestations include a nonspecific minor illness (abortive poliomyelitis), sometimes aseptic meningitis without... read more , Guillain-Barré syndrome Guillain-Barré Syndrome (GBS) Guillain-Barré syndrome is an acute, usually rapidly progressive but self-limited inflammatory polyneuropathy characterized by muscular weakness and mild distal sensory loss. Cause is thought... read more ), and neuromuscular blocking drugs.
1. Izrailtyan I, Qiu J, Overdyk FJ, et al: Risk factors for cardiopulmonary and respiratory arrest in medical and surgical hospital patients on opioid analgesics and sedatives. PLoS One Mar 22;13(3):e019455, 2018. doi: 10.1371/journal.pone.0194553
2. Lee LA, Caplan RA, Stephens LS, et al: Postoperative opioid-induced respiratory depression: A closed claims analysis. Anesthesiology 122: 659–665, 2015. doi: 10.1097/ALN.0000000000000564
Symptoms and Signs of Respiratory Arrest
With respiratory arrest, patients are unconscious or about to become so.
Patients with hypoxemia may be cyanotic, but cyanosis can be masked by anemia or by carbon monoxide Carbon Monoxide Poisoning Carbon monoxide (CO) poisoning causes acute symptoms such as headache, nausea, weakness, angina, dyspnea, loss of consciousness, seizures, and coma. Neuropsychiatric symptoms may develop weeks... read more or cyanide toxicity Systemic Asphyxiant Chemical-Warfare Agents Systemic asphyxiants are a type of chemical-warfare agent and include Cyanide compounds Hydrogen sulfide Systemic asphyxiants have also been called blood agents because they are systemically... read more . Because anemia lowers hemoglobin, reducing the total amount of deoxygenated hemoglobin when a patient is hypoxemic, cyanosis is not as apparent. Carboxyhemoglobin sometimes makes the skin appear red. In cyanide toxicity, patients may not appear cyanotic despite being functionally hypoxic because cyanide impairs cellular respiration. Patients being treated with high-flow oxygen may not be hypoxemic and therefore may not exhibit cyanosis or desaturation until after respiration ceases for several minutes. Conversely, patients with chronic lung disease and polycythemia may exhibit cyanosis without respiratory arrest. If respiratory arrest remains uncorrected, cardiac arrest follows within minutes of onset of hypoxemia, hypercarbia, or both.
Impending respiratory arrest
Before complete respiratory arrest, patients with intact neurologic function may be agitated, confused, and struggling to breathe. Tachycardia and diaphoresis are present; there may be intercostal or sternoclavicular retractions. Patients with CNS impairment or respiratory muscle weakness have feeble, gasping, or irregular respirations and paradoxical breathing movements. Patients with a foreign body in the airway may choke and point to their necks, exhibit inspiratory stridor, or neither. Monitoring end-tidal carbon dioxide can alert practitioners to impending respiratory arrest in decompensating patients.
Infants, especially if < 3 months, may develop acute apnea without warning, secondary to overwhelming infection, metabolic disorders, or respiratory fatigue.
Patients with asthma Asthma Asthma is a disease of diffuse airway inflammation caused by a variety of triggering stimuli resulting in partially or completely reversible bronchoconstriction. Symptoms and signs include dyspnea... read more or with other chronic lung diseases may become hypercarbic and fatigued after prolonged periods of respiratory distress and suddenly become obtunded and apneic with little warning, despite adequate oxygen saturation.
Diagnosis of Respiratory Arrest
Respiratory arrest is clinically obvious; treatment begins simultaneously with diagnosis. The first consideration is to exclude a foreign body obstructing the airway; if a foreign body is present, resistance to ventilation is marked during mouth-to-mask or bag-valve-mask ventilation Bag-Valve-Mask Devices If no spontaneous respiration occurs after airway opening and no respiratory devices are available, rescue breathing (mouth-to-mask or mouth-to-barrier device) is started; mouth-to-mouth ventilation... read more . Foreign material may be discovered during laryngoscopy for endotracheal intubation (for removal, see Clearing and Opening the Upper Airway Clearing and Opening the Upper Airway Airway management consists of Clearing the upper airway Maintaining an open air passage with a mechanical device Sometimes assisting respirations (See also Overview of Respiratory Arrest.) read more ).
Treatment of Respiratory Arrest
Clearing the airway
Treatment is clearing the airway, establishing an alternate airway Airway Establishment and Control Airway management consists of Clearing the upper airway Maintaining an open air passage with a mechanical device Sometimes assisting respirations (See also Overview of Respiratory Arrest.) read more , and providing mechanical ventilation Overview of Mechanical Ventilation Mechanical ventilation can be Noninvasive, involving various types of face masks Invasive, involving endotracheal intubation Selection and use of appropriate techniques require an understanding... read more .