390 likes | 590 Views
Acute Respiratory Insufficiency. NURCAN KIZILCIK. Learning objectives. Definition of acute respiratory insufficiency Diagnosis of acute respiratory insufficiency Causes of acute respiratory insufficiency Clinical and laboratory findings of acute respiratory insufficiency
E N D
Acute Respiratory Insufficiency NURCAN KIZILCIK
Learning objectives • Definition of acute respiratory insufficiency • Diagnosis of acute respiratory insufficiency • Causes of acute respiratory insufficiency • Clinical and laboratory findings of acute respiratory insufficiency • Treatment of acute respiratory insufficiency
one or both of its gas exchange functions: oxygenation and carbon dioxide elimination Results from inadequate gas exchange • Insufficient O2 transferred to the blood • Hypoxemia • Inadequate CO2 removal • Hypercapnia
Not a disease but a condition Result of one or more diseases involving the lungs or other body systems
Respiratory tract Pump System Lungs Gas exchange Oxygenandcarbondioxidecrossthealveolar-capillarywallbydiffusion. Oxygen is transportedfromthelungstothecellsandcarbondioxide is transportedfromthecellstothelungs. Roussos et al, Eur Respir J 2003;22;suppl 47: 3s-14s Laghi and Tobin, AJRCCM 2003;168:10 Ventilation
Inability to sustain • arterial partial oxygen pressure (PaO2) • and carbon dioxide (PaCO2) pressure at physiological range
Clinical findings Tachypnea Dyspnea Stridor Wheezing The use of auxiliary respiratory muscles
Intercostal retractions Sweating Hypertension Mental status changes Tachycardia / bradycardia
Traditionally, respiratory failure is divided into: type 1 and type 2 but these are not practical terms and it is better to think instead of: • Failure to ventilate • Failure to oxygenate • Failure to both ventilate and oxygenate
Respiratory Failure Lung Failure Pump Failure Gas exchangeProblem Hypoxemia Decrease in ventilation Hypercapnia Roussos et al, Eur Respir J 2003;22;suppl 47: 3s-14s
Laboratory • Hypoxia: pO2 < 60 mmHg • Hypercarbia: pCO2 > 45 mmHg
Most important lab indicator of adequate ventilation is arterial partial carbon dioxide level (PaCO2). The normal value is 35 to 45 mmHg.
Partial arterial oxygen (PaO2) is an indicator of adequate of tissue oxygenation. Normal PaO2: 80-100 mmHg at room air. When decreased below this level, tissue hypoxia may occur.
Respiratory physiology The act of respiration engages 3 processes: 1-Transfer of oxygen across the alveolus 2-Transport of oxygen to the tissues 3-Removal of carbon dioxide from blood into the alveolus and then into the environment Respiratory failure may occur from malfunctioning of any of these processes.
Respiration primarily occurs at the alveolar capillary units of the lungs Fig. 66-1
After diffusing into the blood, the oxygen molecules reversibly bind to the hemoglobin. • 1 g of hemoglobin combines with a maximum of 1.36 mL of oxygen.
The carbon dioxide is transported in 3 main forms: 1- in simple solution 2- as bicarbonate 3-combined with protein of hemoglobin as a carbamino compound.
ETIOLOGY Pulmonary% 52 • Pneumonia % 23.7 • Atelectasis % 15.4 • Chronic obstructive pulmonary disease % 13.7 • Pulmonary edema - cardiogenic %9.2 • Aspiration % 5.7 • Pulmonary edema –non-cardiogenic % 4.9
Non- Pulmonary % 47.9 • Abdominal % 18.4 • Central nervous system % 17.2 • Sepsis % 12.3
Hypoxemic respiratory failure The pathophysiologic mechanisms 1-V/Q mismatch: common cause of hypoxemia 2-Shunt: persistence of hypoxemia despite 100% oxygen inhalation
Common causes of type I (hypoxemic) respiratory failure include the following: • COPD • Pneumonia • Pulmonary edema • Pulmonary fibrosis • Asthma • Pneumothorax • Pulmonary embolism • Pulmonary arterial hypertension • Pneumoconiosis • Granulomatous lung diseases • Cyanotic congenital heart disease • Bronchiectasis • Acute respiratory distress syndrome (ARDS) • Fat embolism syndrome • Kyphoscoliosis • Obesity
Diffusion Limitation Fig. 68-5
NORMAL Neuromuscularcapacity Respiratoryworkload RESPIRATORY FAILURE Neuromuscularcapacity Respiratoryworkload Neuromuscularcapacity Respiratoryworkload Laghi and Tobin, AJRCCM 2003;168:10
Increased respiratory workload : • % 30-50 Inspiratory resistance • %100 Elastic recoil • % 100-200 iPEEP -Bronchoconstriction -Bronchial edema -Pulmonary edema -Pulmonary inflammation
Decreased neuromuscular capacity : • Hyperinflation • Critical illness polyneuropathy • Myopathy • Critical illness myopathy • Sepsis • Ventilator-related muscle damage • Drugs • Metabolic abnormalities • Reduction in the transport of oxygen • Drugs • Muscle fatigue
Patient Evaluation • Adequacy of oxygenation is evaluated with • Pulse oximetry (SpO2) • Arterial blood gas • Adequacy of Ventilation • End-tidal CO2 • Arterial blood gas CO2 • Chest x-ray
Cardiopulmonary Tests • Vital signs and organ perfusion • Blood pressure • Skin symptoms • Consciousness / cooperation • Pneumonia • Congestive Heart Failure • Asthma /COPD
Objectives of clinical evaluation • Detection and correction of life-threatening blood gas abnormalities • Determination of ventilation requirements • Noninvasive Positive Pressure Ventilation • Invasive Mechanical Ventilation • Clarify the cause of respiratory failure • Additional diagnostic tests Sigillito et al, Emerg Med Clin N Am 2003;21:239
TREATMENT • Adequate tissue oxygenation must be ensured Provision airway Adequate ventilation should be started Oxygen therapy Blood transfusion Respiratory depression, muscle and nerve function discontinued medications that may affect • The primary cause should be treated • Symptomatic treatment
Oxygen Therapy • Nasal cannula • Simple oxygen mask • partial nonrebreathing mask • Non-rebreathing maske • Large volume nebulizer mask
When Mechanical Ventilation is needed? • PaO2 < 60 mmHg ± PaCO2 > 45 mmHg • Respiratory rate > 30-35 /minute • Abdominal breathing • Rapid shallow breathing • Supporting the use of inspiratory respiratory muscles
Objectives of Mechanical Ventilation • ↑ PaO2 • ↓ PaCO2 • ↓ Acidosis • Unloading of respiratory muscles • Reduce breathlessness
Mechanical Ventilation Treatment Options • Endotracheal intubation + invasivemechanical ventilation • Noninvasive mechanical ventilation
Indications for Intubation • Respiratory arrest • Hemodynamic instability • Confusion • Acute progressive respiratory acidosis • When NIPPV is contraindicated • No response to NIPPV • Hypoxemic patients unresponsive to oxygen therapy
Differential Diagnosis • Pulmonary Diseases • Cardiovascular Diseases • Systemic Diseases