Respiratory failure is a syndrome that develops when the respiratory system is unable to maintain oxygenation and/or ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing. Respiratory failure may be acute or chronic and is classified as hypoxemic, hypercapnic, or a combination of the two. A number of etiologies exist, including diseases of the lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy, cardiovascular, and nervous system Nervous system The nervous system is a small and complex system that consists of an intricate network of neural cells (or neurons) and even more glial cells (for support and insulation). It is divided according to its anatomical components as well as its functional characteristics. The brain and spinal cord are referred to as the central nervous system, and the branches of nerves from these structures are referred to as the peripheral nervous system. Nervous System: Anatomy, Structure, and Classification. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with respiratory failure may present with dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea, tachypnea Tachypnea Increased respiratory rate. Pulmonary Examination, and altered mental status Altered Mental Status Sepsis in Children. The diagnosis is made through measurement of arterial blood gas Arterial blood gas Respiratory Alkalosis and supplemented with laboratory and imaging studies to elicit an etiology. Management involves treating the underlying cause, supplemental oxygen administration, and mechanical ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing for severe cases.
Last updated: 17 May, 2022
Respiratory failure is a syndrome that develops when the respiratory system is unable to maintain oxygenation and/or ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing.
Respiratory failure may be classified based on:
The time course:
The underlying issue:
Diagram of a right-to-left shunt resulting in
hypoxemia
Hypoxemia
Neonatal Respiratory Distress Syndrome:
A
cardiac
Cardiac
Total Anomalous Pulmonary Venous Return (TAPVR) or pulmonary issue causes deoxygenated blood to skip
gas exchange
Gas exchange
Human cells are primarily reliant on aerobic metabolism. The respiratory system is involved in pulmonary ventilation and external respiration, while the circulatory system is responsible for transport and internal respiration. Pulmonary ventilation (breathing) represents movement of air into and out of the lungs. External respiration, or gas exchange, is represented by the O2 and CO2 exchange between the lungs and the blood.
Gas Exchange. When this later mixes with oxygenated blood, the arterial pressure of O2 is reduced.
PA: alveolar
partial pressure
Partial pressure
The pressure that would be exerted by one component of a mixture of gases if it were present alone in a container.
Gas Exchange
PI: inspired
partial pressure
Partial pressure
The pressure that would be exerted by one component of a mixture of gases if it were present alone in a container.
Gas Exchange
Pv
PV
Polycythemia vera (PV) is a chronic myeloproliferative neoplasm characterized by the overproduction of rbcs. In addition, the wbc and platelet counts are also increased, which differentiate pv from erythrocytosis seen with chronic hypoxia and other chronic conditions.
Polycythemia Vera: venous
partial pressure
Partial pressure
The pressure that would be exerted by one component of a mixture of gases if it were present alone in a container.
Gas Exchange
Ppv
PPV
The positive predictive value is the percentage of people with a positive test result who actually have the disease among all people with a positive result, regardless of whether or not they have the disease.
Epidemiological Values of Diagnostic Tests: pulmonary venous
partial pressure
Partial pressure
The pressure that would be exerted by one component of a mixture of gases if it were present alone in a container.
Gas Exchange
A mismatch between ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing and perfusion occurs from a disease process resulting in either:
Note: 100% oxygen 100% Oxygen Cluster Headaches administration can correct oxygenation in V/Q mismatch.
Diagrammatic examples of
ventilation
Ventilation
The total volume of gas inspired or expired per unit of time, usually measured in liters per minute.
Ventilation: Mechanics of Breathing (V) to perfusion (Q) mismatch:
The left side of the diagram shows an example of low
ventilation
Ventilation
The total volume of gas inspired or expired per unit of time, usually measured in liters per minute.
Ventilation: Mechanics of Breathing to an alveolus and normal perfusion, resulting in an
oxygen saturation
Oxygen Saturation
Basic Procedures of 79% (low V/Q ratio).
In the middle, perfusion and
ventilation
Ventilation
The total volume of gas inspired or expired per unit of time, usually measured in liters per minute.
Ventilation: Mechanics of Breathing are matched, which allows appropriate oxygenation of the blood.
On the right, there is normal
ventilation
Ventilation
The total volume of gas inspired or expired per unit of time, usually measured in liters per minute.
Ventilation: Mechanics of Breathing, but low perfusion (high V/Q ratio), which provides more complete oxygenation, but there is less blood
flow
Flow
Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls.
Vascular Resistance, Flow, and Mean Arterial Pressure.
When the blood from these vessels combine, the oxygenation from the middle and right
alveoli
Alveoli
Small polyhedral outpouchings along the walls of the alveolar sacs, alveolar ducts and terminal bronchioles through the walls of which gas exchange between alveolar air and pulmonary capillary blood takes place.
Acute Respiratory Distress Syndrome (ARDS) is not enough to compensate for the poor
ventilation
Ventilation
The total volume of gas inspired or expired per unit of time, usually measured in liters per minute.
Ventilation: Mechanics of Breathing of the left alveolus.
Cyanosis Cyanosis A bluish or purplish discoloration of the skin and mucous membranes due to an increase in the amount of deoxygenated hemoglobin in the blood or a structural defect in the hemoglobin molecule. Pulmonary Examination on a patient’s face due to hypoxemia Hypoxemia Neonatal Respiratory Distress Syndrome
Image: “Clinical signs of chronic hypoxaemia” by Maximilian Patzig et al AL Amyloidosis. License: CC BY 4.0, edited by Lecturio.An arterial blood gas Arterial blood gas Respiratory Alkalosis (ABG) analysis is required in the diagnosis of respiratory failure. It measures and calculates components in arterial blood:
The following parameters are used to define hypoxemic and hypercapnic respiratory failure:
Hypoxemic respiratory failure:
Hypercapnic respiratory failure:
Once hypoxemic respiratory failure is established, the alveolar–arterial (A-a) gradient can be used to help in understanding Understanding Decision-making Capacity and Legal Competence the potential underlying etiology.
The following can be done to evaluate potential causes of respiratory failure. The workup should be tailored to the patient’s presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor and clinical suspicion.
Laboratory evaluation:
Pulmonary function tests:
Imaging:
Management of respiratory failure is supportive and focuses on maintaining adequate oxygenation and ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing until the underlying condition can be treated.
General principles:
Options:
Noninvasive positive-pressure ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing provides ventilatory support without placing an artificial airway Airway ABCDE Assessment.
Indications:
Best suited for:
Options:
Indications:
General principles:
Parameters:
Extracorporeal membrane oxygenation is an advanced therapy utilizing prolonged cardiopulmonary bypass to oxygenate blood and remove CO₂.
Diagram of venovenous ECMO for respiratory failure:
The patient is put on a cardiopulmonary bypass circuit, where venous blood is extracted, oxygenated, and returned to the body.
IVC
IVC
The venous trunk which receives blood from the lower extremities and from the pelvic and abdominal organs.
Mediastinum and Great Vessels: Anatomy:
inferior vena cava
Inferior vena cava
The venous trunk which receives blood from the lower extremities and from the pelvic and abdominal organs.
Mediastinum and Great Vessels: Anatomy
SVC:
superior vena cava
Superior vena cava
The venous trunk which returns blood from the head, neck, upper extremities and chest.
Mediastinum and Great Vessels: Anatomy