Respiratory management after surgery Flashcards
and 02 therapy
What is pulmonary ventilation?
= breathing
= active process: inspiration occurs due to contraction of muscles that cause negative intrathoracic pressure
- Diaphragm main muscle to displace thoracic cage - Flow is generated due to pressure gradient from atmosphere to alveoli - Expiration is passive after intrathoracic pressure is greater than atmosphere
Lung compliance
= Extent to which lungs expand per unit increase in transpulmonary pressure or stretchiness
- Defined as the volume change per unit pressure change
- Low compliance = lungs are stiffer, and more effort required to inflate alveoli (pulmonary oedema)
- High compliance = easy inflation and loss of elasticity e.g. emphysema
Lung resistance
= obstruction to flow of airways
- Resistance is normally low, most arising from airways e.g. nose of pharynx
- Increases in resistance – oedema, obstruction, spasm, airway obstructive disease
Alveolar capillary network
= has a large surface area that provides the basis for an optimized gas exchange in the lung.
- Each alveolus surrounded by capillary network - Alveoli – thin epithelial cells and capillary – thin endothelial cells lining alveolar
Post operative pulmonary risk factors
- age
- obesity
- health status
- smoking
- lung disease
7 risk factors of surgery
o Low pre-operative Sp02
o Acute resp infection pre-op
o Age
o Pre-op anaemia
o Upper abdominal or intrathoracic
o Surgery duration > 2 h
o Emergency surgery
Post operative pulmonary risk factors evaluation
• History and physical examination
• Chest X-ray
o >50 year age
o Pre-existing pulmonary disease
o Suspected cardiac or pulmonary disease
• Arterial blood gas
o Hypercapnia
• Lung function test - spirometry
• Exercise tolerance test
• Lung scan?
• Type of surgeryPost operative pulmonary complication
- bronchospasm
- cough
- atelectasis
- dyspnoea
- hypoxaemia/hypoxia
- pleural effusion
- pneumonia
Post operative pulmonary complication Bronchospasm
• Intraoperative complication
• Clinical manifestations
o Wheeze, tachypnoea, hypercapnia
- Histamine release causing mast cells degranulation
- Reflex bronchoconstriction due to tracheal stimulation from secretions suctioning
- Treatment: remove cause, beta-2-agonist
Post operative pulmonary complication cough
- Usually initiated in larynx + tracheo-bronchial tree
- Function: maintenance of airway patency
- Airway irritation: irritant receptors in large airways
Most sensitive areas: • Larynx • Carina • Trachea • Major brunch
Postoperative reasons
• Dry airway
• Irritated upper airways
• Cough reflex
Post operative pulmonary complication atelectasis
= incomplete expansion
• Diminished volume affect part or all of the lung
• Common post-operative pulmonary complication
• Pathophysiology
o Post operative pain
o Retain airway secretion
• Clinical manifestations
o Can be asymptomatic, minor to severe symptoms, dependent on magnitude of lung collapse
o Cough and dyspnoea common
• Diagnosis
o Chest X-ray, lung sounds, ABG, symptoms
• Treatment
o Early mobilisation and incentive spirometry
o Posture drainage, chest wall percussion
o Coughing, nebulised bronchodilators
o Positive pressure ventilation
o Oxygen and antibiotics
Post operative pulmonary complication dyspnoea
- Subjective sensation of uncomfortable breathing
- Common symptom of respiratory disease
- V/Q mismatches
- Lung disease
- May relate to stretch receptor
- Paroxysmal nocturnal dyspnoea
- Posture induced
Post operative pulmonary complication hypoxaemia/ hypoxia
= low blood or tissue oxygen level
causation
- Hyperventilation, V/Q mismatch, decreased alveolar diffusion
Pathophysiology
• Depression of minuet ventilation
• Shunting of gas volume from under ventilated alveoli
• Decrease in gas volume to under perfused alveoli
Clinical manifestiations • dependent on magnitude of hypoxaemia and / or hypoxia • tachypnoea • dyspnoea • cognitive changes • arrhythmias • vasodilation and hypotension cyanosis and coma (very late signs!)
Diagnosis: - Clinical presentation, oxygen saturation, ABG
Treatment
• Reverse cause
• Supplemental oxygen
• Positioning
• Positive pressure ventilation
Post operative pulmonary complication pleural effusion
2 types: transudative (watery and protein-poor) and exudative (protein rich fluid)
Causation:
• imbalance between fluid production and removal
• inadequate lung expansion
• disruption to pleural membrane
Clinical manifestations
• Cough, dyspnoea, pleural friction rub, decreased breath sounds
Diagnosis
• Clinical examination
• Chest x ray
Treatment
• Often nothing as resolves once patient is active
• Chest physiotherapy
• Oxygen therapy if severe
• Can need drainage
Post operative pulmonary complication Pneumonia
- Postoperative pneumonia diagnosed and presents similar to hospital acquired
- Occurs within 5 days postoperative
- Fever, leucocytosis, increased secretions, pulmonary infiltrates on chest x-ray
- Diagnosis: controversial – generally all patient suspected of infection with x-ray infiltrates
- Difficult because many other conditions similar – atelectasis, pulmonary oedema
Treatment
• Oxygen
• Analyses sputum cultures and treat antibiotics empirically
• Position
• Positive airway pressure
PH range
pH < 7.35 or > 7.45
Auscultation
= listening to chest sounds
- the character of breath sounds
- present of abnormal sounds
- character of spoken/whispered voice
Bronchovesicular sounds
- heard in the centre part of the 1st & 2nd ICS, anterior chest and in the posterior chest between the scapulae. (ie over mainstem bronchi) -
- softer than bronchial sounds, but have a tubular quality. about equal during inspiration and expiration; -
- abnormalities in pitch and intensity are often more easily detected during expiration.
Vesicular sounds
- Soft, blowing or rustling sounds normally heard throughout most of the lung fields
- Normally heard throughout inspiration, continue without pause through expiration and then fade away about one third of the way through expiration
goal of oxygen therapy
= Goal is to provide sufficient concentration of inspired oxygen to permit full use of oxygen carry capacity of the arterial blood thus ensuring adequate cellular oxygenation given an adequate cardiac output and HB concentration
Room air
o 21% oxygen
o 78% nitrate
o 1% other gases
hypercapnia
Increased amounts of carbon dioxide in the blood.
Hypoxemia
= low arterial oxygen tension (in the blood
Hypoxia
= low oxygen level in tissues
low flow
= low flow systems are specific devices that do not provide thee patient’s entire ventilatory requirements
