Surgery Flashcards
Who is most at risk going under anaesthetic?
Smokers, obese, elderly, malnourished
Smokers
Decreased cilial activity
Increased bronchial secretions
Weak immune system
Higher closing volume
Elderly
Decreased lung compliance
Stiffer thoracic cage
Reduced effectiveness of thermoregulation- anaesthetic affects re-distribution of body heat, can change core temp by 0.5-1.5 which can be dangerous for elderly. Elderly more likely to drop temp and not recover quickly.
Obese
Reduced FRC
Higher CC
Increased effort to move thoracic cage
Poor basal expansion
Effect of upper abdominal surgery
Affects diaphragm function
Patient’s won’t want to take deep breaths so at risk for atelectasis
Surgery complications
Pain Reduced lung volumes- FRC, VC Retained secretions Increased work of breathing Decreased exercise tolerance Hypoxaemia Respiratory muscle weakness
Why are the lower lobes most at risk of atelectasis?
Because they are the last to receive oxygen especially when in pain
Thrombosis
Caused by immobility
Fluid loss
Abnormal clotting
Calf compression
When is generally the greatest reduction in FRC post op?
1st/2nd day
Obesity and FRC
Massive reduction in FRC post op
Effect of general anaesthetic on respiratory system
Reduced lung volumes
Especially FRC
VC and FRC after surgery
VC can reduce to 40% of pre op values
FRC can reduce to 70% of pre op values
How long do VC and FRC changes last?
5-10 days
Relationship between FRC and closing capacity (CC)
FRC normally exceeds CC, so small airways stay open at end of quiet expiration.
But if FRC falls below CC or CC rises above FRC, this could result in V/Q mismatch and hypoxaemia.
What are 2 inevitable consequences of major surgery?
Post op hypoxaemia and atelectasis
How can we counter these consequences?
Early upright positioning and mobilization
Because this will optimize FRC
Post op pulmonary complications can cause…
Post op morbidity and mortality.
Increased length of stay.
PPC risk factors
Anaesthesia duration greater than 180 minutes Type of surgery- upper abdominal Current smoking (within last 8 weeks) Presence of pre op respiratory problems Reduced level of pre op activity Sleep apnoea Advanced age
What can exacerbate post op changes such as impaired respiratory fucntion?
Obesity
Positioning after pneumonectomy
Positioned onto operated side so remaining lung is uppermost
What is a serious complication of pneumonectomy?
Pulmonary oedema
Look for a positive fluid balance, with tachycardia, tachypnoea and hypoxaemia
Positioning after oesophageal surgery
Avoid head down positioning
To prevent gastric reflux which can lead to aspiration
Avoid neck extension
Positioning after lobectomy and pleurectomy
Side lying and head down has no contraindication
Thoracic surgery and positive pressure therapies
With caution or not at all
Management of sternal and rib fractures
Requires effective pain relief to prevent hypoventilation
Ensure they can take a deep breath
Flail chest
Where 2 or more ribs are fractured in 2 or more places leading to a floating segment
Causes severe pain and increased WOB which can lead to respiratory failure due to poor ventilation of underlying lung.
Treatment for flail segment
CPAP
Effect of prolonged recumbency
Reduces ventilation to lung bases, causes poling of intra-thoracic blood to these regions which upsets V/Q.
Cause of brief post op hypoxaemia
Due to anaesthetic
Requires brief oxygen therapy
Cause of post op hypoxaemia for several days
Related to the surgery
Major surgery requires post op oxygen therapy for at least 72 hours
What is common after CV surgery?
Atrial fibrillation
Usually second day
Melbourne group scale
PPC diagnosed with four of more of:
CXR shows atelectasis/consolidation
Fever with raised temp
WCC of more than 11.2
SpO2 less than 90% on room air
Production of yellow/green sputum differing from preop status
Signs of infection on microbiology
Diagnosis of pneumonia or chest infection by attending physician
Readmission to ICU with respiratory problems or >36 hours stay in ICU or abnormal breath sounds differing to pre op status
Incidence of atelectasis
0-5% in lower abdominal surgery
19-59% in thoracic surgery
88% in upper abdominal surgery.
