Diagnosis of acute respiratory failure

Symptoms of acute respiratory failure are varied and depend on the cause and effect of violations of the gas composition of blood on the target organs - lungs, heart, nervous system. There is no specific symptomatology of acute respiratory failure.

Clinical manifestations of acute respiratory failure

System	Symptoms
General state	Weakness, sweating
Respiratory system	Tachypnea Bradypnoe Apnea Decrease or absence of respiratory sounds Cyanosis Paradoxical breathing Inflating the wings of the nose Breath-exhaling Wheezing
The cardiovascular system	Tachycardia Bradycardia Hypertension Hypotension Arrhythmia The paradoxical pulse Heart failure
CNS	Edema of the optic nerve Respiratory encephalopathy Coma Asterixis

When a child has one or more clinical signs, it is necessary to analyze the blood gas composition, which allows not only to confirm the diagnosis of acute respiratory failure, but also to monitor the clinical development of the process. Blood gas composition - the "gold standard" intensive therapy: p _a O ₂, S _and O ₂, p _a CO ₂ and pH. Additionally, it is possible to measure carboxyhemoglobin (HbCO) and methemoglobin (MetHb). Blood for examination is taken from any part of the vascular system (venous, arterial, capillary), thus obtaining various values for the assessment of oxygenation and ventilation.

Hypoxemia - reduction of p _and O ₂ <60 mm Hg and S _a O ₂ <90% in the blood. For the initial stage, tachypnea, tachycardia, moderate arterial hypertension, narrowing of peripheral vessels are characteristic; in the future develop bradycardia, arterial hypotension, cyanosis, intellectual disruption, convulsions, disorientation, coma. With mild hypoxemia, mild hypoventilation appears, a violation of intellectual function and vision. Severe hypoxemia (r _a O ₂ <45 mm Hg) causes pulmonary hypertension. Violation of cardiac output, myocardial and renal functions (sodium retention), CNS (headaches, somnolence, seizures, encephalopathy), leads to anaerobic metabolism followed by the development of lactic acidosis.

Hypercapnia (р _а СО ₂ > 60 mm Hg) also leads to impaired consciousness and heart rhythm, arterial hypertension. Early diagnosis and assessment of severity depends on the results of analysis of the gas composition of the blood.

Side effects of hypoxemia, hypercapnia and lactate-acidemia have synergistic or aditivistic effects on other organs. Respiratory acidosis potentiates the hypertensive effect caused by hypoxemia, and enhances neurologic symptoms.

Cyanosis is an important indicator of acute respiratory failure.

Cyanosis is of two types:

• central;
• peripheral.

Central cyanosis develops in the pathology of the respiratory system or with certain congenital heart defects and manifests itself in hypoxemic hypoxia. Peripheral cyanosis is a consequence of hemodynamic problems (ischemic hypoxia). Cyanosis is absent in patients with anemia, until the onset of severe hypoxemia.

A general clinico-laboratory evaluation is needed, as the degree of respiratory distress does not always correlate with the degree of oxygenation and alveolar ventilation. In connection with the various manifestations of acute respiratory failure in children there are certain difficulties in diagnosis. For clinical and laboratory diagnosis of acute respiratory failure, its timely and correct evaluation is necessary.

The main criteria for diagnosis of acute respiratory failure in children

Clinical	Laboratory
Tachypnea-bradypnoea, apnea Paradoxical pulse Reduction or absence of respiratory noise Stridor. Wheezing, grunting Expressed retraction of compliant places of the thorax with the use of an auxiliary respiratory musculature Cyanosis with the introduction of 40% oxygen (exclude congenital heart disease, impaired consciousness of varying degrees	P a CO 2 <60 mm Hg. With the introduction of 60% oxygen (to exclude congenital heart disease) P a CO2. > 60 mm Hg PH <7.3 Vital capacity of lungs <15 ml / kg Maximum inspiratory pressure <25 cm of water,

[1], [2], [3], [4], [5], [6], [7], [8], [9], [10]