Respiratory Failure Causes Clinical Features with Management

Respiratory Failure

• Respiratory failure is defined as inadequate gas exchange due to malfunction of one or more components of the respiratory systemThe cardiac axis Right Axis Deviation and Left Axis Deviation Causes and Treatment. Read more ... ».

Respiratory failure means:

• Hypoxaemia – P0₂ <60 mmHg, or y Hypercarbia – PC0₂ >45 mmHg.
• So, respiratory failure may be hypoxaemic, hypercarbic or combined.

• Hypoxemic

  • respiratory failure is defined by arterial O₂ saturation <90% while receiving an inspired O₂ fraction >0.6.
  • AcuteThe cardiac axis Right Axis Deviation and Left Axis Deviation Causes and Treatment. Read more ... » hypoxemic respiratory failure can result from pneumonia, pulmonary edemaPulmonary Edema Causes Diagnosis with Treatment. Read more ... » (cardiogenic or noncardiogenic), and alveolar hemorrhage. Hypoxemia results from ventilation-perfusion mismatch and intrapulmonary shunting.

• Hypercarbic

  • respiratory failure is characterized by respiratory acidosisAcidosis & Alkalosis physiology with signs and symptoms. Read more ... » with pH <7.30. Hypercarbic respiratory failureMechanical Ventilation Support in Critical Care. Read more ... » results from decreased minute ventilation and/or increased physiologic dead space.

Respiratory failure may be acute or chronic.

• Acute respiratory failure is sudden and life-threatening.
• ChronicChronic Hepatitis Classification viral hepatitis Clinical features and Treatment. Read more ... » respiratory failure occurs gradually and compensation and adaptations in various organ sys­tems occur ..
• Respiratory insufficiency means that there is a compensated state in a patient with respiratory dis­ease and impaired function.

Four different types of respiratory failure can be present:

• Type I:
  • There is acute hypoxemic respiratory failure. d” There is alveolar congestion.
  • Ex. Pulmonary oedema, pneumonia, lung injury,
• Type II –
  • there is hypercarbia
  • it is seen in bronchial asthmaBronchial Asthma Etiology Pathogenesis Clinical features Treatment of Bronchial Asthma. Read more ... », pneumothorex, drugThe cardiac axis Right Axis Deviation and Left Axis Deviation Causes and Treatment. Read more ... » overdose,
  • brain stem injury,hypothyroidismACTH and TSH DEFICIENCY Diagnosis with Treatment. Read more ... »,
  • sleepSleep Disorders Types Diagnose Of Sleep Disorders. Read more ... » disorders, myasthenia gravis,
  • GB syndromeMetabolic,Insulin Resistance Syndrome X Causes Symptoms. Read more ... », myopathy etc.
• Type III :
  • This is due to lung collapse.
  • It is also called perioperative respiratory failure.
• Type IV:
  • This occurs in shockShock Presentation Risk Factors Pathogenesis Management Treatment. Read more ... » due to hypoperfusion of res­piratory muscles.

^aOpen lung ventilation (OLV) involves the use of any of these specific modes with tidal volumes (or applied pressures) to achieve 5—6 mL/kg, and positive end-expiratory pressures achieve maximal alveolar recruitment.

^b FIo₂ is usually set to 1.0 initially, unless there is a specific clinical indication to minimize FIo₂, such as history of chemotherapy with bleomycin. Once adequate oxygenation is documented by blood gas analysis, FIo₂ should be decreased in decrements of 0.1—0.2 as tolerated, until the lowest FIo₂ required for an Sao₂ >90% is achieved. Abbreviations: f, frequency; I/E, inspiration/expiration; FIo₂, inspired O₂; PEEP, positive end-expiratory pressureChronic Long-term Complications Of Diabetes Mellitus. Read more ... »; for ventilator modes, see text; VtVentricular Tachycardia VT Diagnosis Causes Clinical features with Treatment. Read more ... », tidal ventilation.

 

Ventilator Mode	Independent Variables (Set by User)	Dependent Variables (Monitored by User)	Trigger/Cycle Limit	Advantages	Disadvantages	Initial Settings
ACMVa	FIO2 Tidal volume Ventilator rate Level of PEEP Inspiratory flow pattern Peak inspiratory flow Pressure limit	Peak airway pressure, PaO2, PaCO2 Mean airway pressure I/E ratio	Patient/timer Pressure limit	Timer backup Patient-vent synchrony Patient controls minute ventilation	Not useful for weaning Potential for dangerous respiratory alkalosisAcidosis & Alkalosis physiology with signs and symptoms. Read more ... »	FIO2 = 1.0b Vt = 10–15 mL/kga f = 12–15/min PEEP = 0–5 cmH2O Inspiratory flow = 60 L/min
SIMVa	Same as for ACMV	Same as for ACMV	Same as for ACMV	Timer backup useful for weaning	Potential dyssynchrony	Same as for ACMVa
PCVa	FIO2 Inspiratory pressure level Ventilator rate Level of PEEP Pressure limit I/E ratio	Tidal volume Flow rate, pattern Minute ventilation PaO2, PaCO2	Timer/patient Timer/pressure limit	System pressures regulated Useful for barotrauma treatmentThe cardiac axis Right Axis Deviation and Left Axis Deviation Causes and Treatment. Read more ... » Timer backup	Requires heavy sedation Not useful for weaning	FIO2 = 1.0b PC = 20–40 cmH2Oa PEEP = 5–10 cmH2O f = 12–15/min I/E = 0.7/1–4/1
PSV	FIO2 Inspiratory pressure level PEEP Pressure limit	Same as for PCV + I/E ratio	Inspiratory flow Pressure limit	Assures synchrony Good for weaning	No timer backup	FIO2 = 0.5–1.0b PS = 10–30 cmH2O 5 cmH2O usually the level used PEEP = 0–5 cmH2O

 

Causes of respiratory failure:

• Nervous system

  • The medulla and its neural pathways control res­piration. Dysfunction of this pathway results in central apnoea.

•  Muscles of respiration

   

  • The dia hr m, the intercostal muscles, su­prasternal, sternoCleidomastoid and other small muscles are responsible for the motor part ‘Of respiration. Muscle paralysis results in respira­tory failure.

• Airways

  • If there is obstruction of air passages – ~ airways, bronchi or alveoli, then due to airway system sfunction, there can be respiratory failure.

• Alveolar system

  • In colla se of lung, congestion, injury, there is alveolar system dysfunction. -

• Vasculature

  • The pulmonary vasculature, if diseased, can lead to respiratory failure.

Clinical Features of respiratory failure

• Upper airway should be checked. There may be cen­tral or peripheral ganosis. Respirator .related deth and pattern of respiration ma be altered.
• There may be flarin of nostrils ursed li s use of accessory muscles of respiration.
• Oxygen and CO₂ in arterial blood is estimated by ar­terial blood gas analysis. Pulse oximetry is done.
• To assess which part of the respiratory system is re­sponsible for the respiratory failure, the folloWing table is useful:

 Nervous system

• Respiratory rate is < 12jmin., with hypoxia,hypercarbia and acidemia.

 Muscular dysfunction

• The vital capacity is < 10 ml/kg and inspiratory force is < -20 cm H₂0.
• There is presence of paradoxical respiratory motion.

 Airway dysfunction

• There is wheezing or ronchi and raw airway re­~istance > 10 cm H₂0/ L /sec.

 

Alveolar disease

• There is consolidation of lungs. PaC0₂ is elevated. Chest x-ray shows infiltrates.

Pulmonary vascular disease

• JVPExamination of arterial pressure pulse with Jugular Venous Pulse (JVP). Read more ... » is raised. ECGThe cardiac axis Right Axis Deviation and Left Axis Deviation Causes and Treatment. Read more ... » shows RVH with strain p~t- tern or RBBB.

Management of Respiratory Failure

• General care of mechanically ventilated pts is reviewed along with weaning from mechanical ventilation. A cuffed endotracheal tubeABDOMINAL PARACENTESIS / ASCITIC TAP. Read more ... » is often used to provide positive pressure ventilation with conditioned gas
• Airway protection, oxygenation, and ventilation is provided.
• Supplemental oxygen is given.
• Noninvasive positive pressure ventilation (NPPV) refers to positive pressure ventilation delivered through a noninvasive interface (nasal mask, facemask, or nasal plugs), rather than an invasive interface (endotracheal tube, tracheostomy).
• Airway is opened with head tilt – chin lift ma­neuver, foreign body removed.
• After an endotracheal tube has been in place for an extended period of time, tracheostomy should be considered, primarily to improve pt comfort and management of respiratory secretions.
• Suction is done for vomit or blood. Tracheostomy may be required.
• Adequate oxygenation – 100% oxygen is given. Artificial ventilation/Mechanical ventilation, if required, is started.
• Endotracheal intubation may be done for me­chanical ventilation.
• PEEP is given in patients with mechanical venti­lation.
• In some circumstances, noninvasive positive pressure ventilation (NPPV) delivered through a tightly fitting nasal or full facemask should be considered for treatment of impending respiratory failure
• Cause of respiratory failure assessed. Treat infections.
• Anti-inflammatory or immuno-suppressive drugs are given.
• Bronchodilators.
• Anticoagulants or thrombolytics. Diuretics.

Triggering —

• Ventilators can be triggered by a change in alveolar pressure (ie, pressure triggered) or flow (ie, flow triggered)
• The trigger sensitivity is usually set at -1 to -2 cmH2O when pressure triggering is used.
• The trigger sensitivity is usually set at 2 L/min when flow triggering is used.

Auto-PEEP —

• Intrinsic positive end-expiratory pressure (ie, intrinsic PEEP or auto-PEEP) can be measured in a relaxed patient by occluding the expiratory port of the ventilator circuit