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Acute Respiratory Obstruction and Restriction. ICU nurses course 2004 Tim Smith. Topics. Asthma (acute bronchospasm) Acute Exacerbation of COPD Pneumothorax Pleural Effusion. Acute Asthma. Asthma. Chronic inflammatory condition of the lung airways characterised by:

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acute respiratory obstruction and restriction

Acute Respiratory Obstruction and Restriction

ICU nurses course 2004

Tim Smith

topics
Topics
  • Asthma (acute bronchospasm)
  • Acute Exacerbation of COPD
  • Pneumothorax
  • Pleural Effusion
asthma
Asthma

Chronic inflammatory condition of the lung airways characterised by:

    • Reversible airflow limitation
    • Airway hyperresponsiveness
    • Bronchial inflammation
  • Increasing prevalence
  • 10-15% of pop. In 2nd decade
pathogenesis
Pathogenesis
  • Extrinsic vs. Intrinsic
  • Mast cells (histamine, LTC4, PGD2)
  • T cells (cytokines)
  • Eosinophils (ECP, MBP)
  • C-fibres (NKA, CGRP, SubP)
precipitating factors
Precipitating Factors
  • Allergens
    • Flour
    • Washing powder
    • Animals
  • Non-specific
    • Exercise
    • Cold air
    • Emotion
  • Occupational
    • Isocyanates
    • Colophony fumes
mechanisms
Mechanisms
  • Bronchoconstriction
  • Airway inflammation
    • Microvascular leak
    • Oedema
  • Increased (viscid) mucus production

AIRWAY OBSTRUCTION

physiological effects
Physiological Effects
  • Increased work of breathing
    • Accessory muscle use
    • Increased oxygen demands
  • Air trapping
    • Prolonged active expiratory phase
    • Auto-PEEP
  • V/Q mismatch
    • Hypoxia
  • Increased respiratory drive
clinical features 1
Clinical Features 1

Related to severity:

  • Moderate asthma exacerbation
    • Breathlessness
    • Wheeze (expiratory)
    • PEF 50-75%
clinical features 2
Clinical Features 2
  • Acute Severe Asthma

One of:

    • PEF 33-50%
    • RR >= 25 /min
    • HR >= 110/min
    • Inability to complete sentences
clinical features 3
One of:

PEF <33%

SpO2 <92%

PaO2 <8kPa

Normal PaCO2

Silent chest

Cyanosis

Feeble respiratory effort

Bradycardia

Dysrhythmia

Hypotension

Exhaustion

Confusion

Coma

Clinical Features 3
  • Life threatening Asthma
clinical features 4
Clinical Features 4
  • Near Fatal Asthma

One of:

    • High PaCO2
    • Mechanical ventilation
chest x ray
Chest X Ray
  • Hyperinflation
  • Flattened diaphragm
mri with he 3
MRI with He3

Before

40 min after Albuterol

medical therapy
Medical Therapy
  • Oxygen
  • β2-agonists
    • Nebulised if possible
  • Steroids
  • Ipratropium Bromide
  • Magnesium Sulphate
    • Life threatening or poor response
  • Aminophylline
    • Perhaps in some patients
indications for itu
Indications for ITU
  • Deteriorating PEF
  • Worsening hypoxia
  • Hypercapnia
  • Worsening acidosis
  • Altered conciousness
  • Exhaustion
  • Respiratory arrest
itu treatment
ITU treatment
  • Continue full medical treatment
  • NIV
    • Perhaps
  • IPPV
    • For worsening hypoxia/hypercapnia
    • Exhaustion
    • Reduced concious level
  • Optimise
    • Fluid status
    • Hypokalaemia (steroids, β2-agonists)
ventilation
Ventilation
  • Conventionally volume controlled
  • Slow rate
  • Long expiratory time
  • Low/no PEEP

eg. MV 115 ml/kg, TV 6-8 ml/kg, RR 8-10, PEEP 0

  • FiO2 to keep SpO2 >=94%
  • Remember: hypotension, pneumothorax, EMD
acute exacerbation of copd1
Acute Exacerbation of COPD
  • COPD affects 5% of adult population
  • Fifth most common cause of death world wide.
  • Chronic irreversible disease
  • Acute deterioration can be precipitated by diverse causes
pathologic processes
Pathologic Processes
  • Bronchiolitis (inflam. airway narrowing)
  • Loss of connective tissue tethering
  • Loss of alveoli and capillaries
  • Increased closing volume
  • Increased pulmonary vascular resistance
  • Resulting in:
    • V/Q mismatch
    • Increased resistance
    • Dynamic hyperinflation
    • Increased work of breathing
causes of exacerbations
Causes of Exacerbations
  • Infection (50%)
  • Heart Failure (25%)
  • Sputum Retention
  • PE
  • Pneumothorax
  • Sedation
  • Medication
  • Malnutrition
treatment
Treatment

Treat underlying cause and support:

  • Oxygen (titrate avoiding carbonarcosis)
  • Bronchodilators
  • Steroids (not if pneumonic cause)
  • Antibiotics for infectious cause
  • Clearance of secretions
    • Physio, mucolytics, suctioning, bronchoscopy
  • Hydration, Diuretics, Vasodilators
  • DVT prophylaxis
  • Nutrition
  • no benefit from respiratory stimulants
non invasive ventilation 1
Non-invasive Ventilation 1
  • Ventilatory support via nasal/facemask
  • Aims:
    • Unload respiratory muscles
    • Augment ventilation
    • Improve oxygenation
    • Reduce CO2
non invasive ventilation 2
Non-invasive Ventilation 2

Indicated for:

Worsening COPD with:

  • Acute dyspnoea
  • RR >28/min
  • PaCO2 > 6kPa and pH < 7.35

in spite of maximal medical therapy and not related to XS O2

invasive ventilation 1
Invasive Ventilation 1
  • Indications:
    • Exhaustion despite NIV
    • Deteriorating concious level
    • Hypoxia
    • Failure of secretion clearance
    • Respiratory arrest
  • Need for mechanical ventilation dramatically decreases survival.
  • Weaning often difficult.
invasive ventilation 2
Invasive Ventilation 2
  • Strategy:
    • Low RR
    • Low TV
    • Prolonged expiration
  • Pitfalls:
    • Dynamic hyperinflation
    • Barotrauma
    • Prolonged difficult wean
invasive ventilation 3
Invasive Ventilation 3
  • Outcome:
    • ITU mortality 10-30%
    • 1 year survival 50%
    • Depends more on previous state, nutrition, age than on measured variables.
pneumothorax
Pneumothorax

Pathological collection of extraalveolar air in the pleural space.

causes
Causes
  • Spontaneous:
    • Primary – no underlying lung disease
    • Secondary – COPD/CF/AIDS/Ca/chemo
  • Traumatic:
    • blunt or penetrating chest trauma
    • iatrogenic – central lines/surgery
  • Barotrauma:
    • positive pressure ventilation (4-15%)
    • ARDS & IPPV (up to 60%)
    • (COPD/asthma)
clinical features 11
Clinical Features 1
  • Decreased or absent breath sounds
  • Hyperresonant percussion
  • Chest pain
  • Dyspnoea (worse if secondary)
  • Tachycardia
  • Pleural line & lucent space on CXR
  • Hypoxaemia (if large)
clinical features 21
Clinical Features 2
  • Pneumothorax may be difficult to detect in ventilated patient with poorly compliant lungs:
    • Stiff lungs do not collapse readily
    • Gas exchange often already disordered
    • Subtle early signs:
      • Decreased urine output
      • Increased CVP
      • Tachycardia
      • Decreased CI
    • High index of suspicion
    • CT scanning may be useful
tension pneumothorax
Tension Pneumothorax
  • One way valve effect
  • Intrapleural gas accumulates
  • Displacement of mediastinum
  • Compression of contralateral lung
  • Hypoxaemia due to shunt
  • Decreased VR and CO
  • Hypotension and EMD arrest
treatment 1
Treatment 1
  • Spontaneously breathing patient
    • Small pneumothorax (<20%) if asymptomatic can be treated conservatively.
    • Larger pneumothorax must be aspirated or drained.
    • Recurrence requires pleurodesis
treatment 2
Treatment 2
  • Ventilated patient:
    • Low threshold for draining pneumothoraces as risk of tension
    • Place chest drain in patient with pneumothorax requiring ventilation
treatment 3
Treatment 3
  • Tension pneumothorax:
    • Potentially rapidly fatal
    • Rapid decompression based on clinical diagnosis improves survival
    • Don’t wait for the X-ray
pleural effusion
Pleural Effusion
  • Pathological collection of fluid within the pleural space.
  • Starling Forces normally keep pleural space dry.
  • Effusion results from:
      • Increased pulmonary capillary pressure
      • Increased capillary permeability
      • Hypoalbuminaemia
      • Lymphatic obstruction
clinical features
Clinical Features
  • Pleuritic pain
  • Cough
  • Dyspnoea.
  • Decreased air entry
  • “stony” dullness
  • Restrictive defect
radiology
Radiology
  • CXR (upright PA)
    • >300ml loss of costophrenic angle
    • Larger effusions cause opacification
  • Lateral decubitus films
    • more sensitive (5ml)
    • Impractical on ITU
  • USS
    • Extremely sensitive (2ml)
    • Can be used to guide drainage
thoracocentesis
Thoracocentesis

May help determine cause:

  • Transudate vs. Exudate
    • (prot >3g/dl, sg >1.016)
    • Imbalance in Starling Forces vs increased pleural membrane permeability
  • Low glucose suggests infection/rheumatoid
  • High amylase suggests pancreatitis
  • WCC>10mm-3 suggests infection
  • Gram stain and culture may ID pneumonic cause
  • pH <7.1 = empyema
treatment1
Treatment
  • Treatment of underlying condition where appropriate
  • Drainage if:
    • Empyema
    • Ventilatory compromise
    • h/o trauma (suspect haemothorax)
  • Pleurodesis
  • VATS/Thoracotomy
  • Pleuroperitoneal shunts
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