Respiratory complications post op

Question 1

Give a summary of the pulmonary anatomy and physiology, including:

• ventilation
• compliance
• resistance
• alveolar-capillary network /alveolar ventilation

Answer 1

Pulmonary ventilation
> Active process: inspiration occurs due to contraction of muscles (using ATP) 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 (specifically intraalveolar) pressure is greater than atmosphere

Compliance:
> Definition: extent to which lungs expand per unit increase in transpulmonary pressure or stretchiness
> Volume change per unit pressure change:
○ C= V / P
> Normal is 200ml.cm of water
> Low compliance- lungs are stiffer and increase effort required to inflate alveoli
> High compliance- easy inflation + loss of elasticity

Resistance
> Definition: obstruction to flow in the airways mainly larger
> Resistance is normally low, most arising from upper airways
> Increase in resistance= oedema, obstruction, spasm

Alveolar-capillary network
> Each alveolus surrounded by capillary network.
> Alveoli - thin epithelial cells + capillary- thin endothelial cells lining alveolar-capillary

Alveolar ventilation
> Dead space= does not participate in gas exchange
> Functional dead space= alveoli not perfused with blood but expanded with air

Question 2

What are some pre-op risks and assessments for pulmonary complications?

Answer 2

• Peri-operative mortality rate= the highest risk is at 24hrs or 30 days after
• Risk factors: urgency, age, condition
• Pre operative pulmonary risk factor evaluation:
○ History and physical exam, chest x ray, arterial blood gas, lung function tests, type of surgery, exercise tolerance test

Question 3

Summarise the post op risks of pulmonary complications.

Answer 3

• Risk factors: age, obesity, health status, smoking, lung disease
• Post operative pulmonary complications:
○ Complications: bronchospasm, cough, atelectasis, hypoxaemia, pneumonia
○ Risk factors- Low pre op SpO2, age, pre op anaemia, surgery duration, emergency surgery

Question 4

Discuss the characteristics and treatment for bronchospasm.

Answer 4

• intraoperative complication = uncommon 2%
• Clinical manifestations: wheeze, tachypnea, hypercapnia
• histamine release causing mast cells (inflammatory response) degranulation occurs due to reflex bronchoconstriction due to tracheal stimulation from secretions, suctioning
  Treatment= remove the cause, beta 2 agonist

Question 5

Discuss reasons and characteristics of coughing.

Answer 5

• coughing is really complex can be good or bad by using extra energy if you have sutures etc.
• usually initiated in larynx and tracheo bronchial tree
• it is a protective mechanism due to airway irritation in large airways
  most sensitive areas= larynx, carina, trachea, major bronchi
• post op reasons= dry airway, irritated upper airway

Question 6

Discuss dyspnoea characteristics

Answer 6

• It is a subjective sensation of uncomfortable breathing
• common symptom of respiratory distress
• V/Q mismatch
• lung disease
• may relate to stretch receptors
  examples:
  there is paroxysmal nocturnal dyspnoea (sudden attack) which is an acute shortness of breath at night.
  Also posture-induced dyspnoea: orthopnoea= lying position, characteristic of heart failure.
  assess it by asking patient to rate it 1-10.

Question 7

Describe Atelectasis.

Answer 7

> It is an incomplete expansion or extension of the lungs
diminished volume affect part of all of the lung
common post operative pulmonary complication: especially upper abdominal and thoracic surgery
usually bi-basal and segmental
pathophysiology= decrease expansion and lung compliance, retained airway secretion, post operative pain
Clinical manifestations: can be asymptomatic, minor to severe symptoms, depends on lung collapse. cough and dyspnoea common. Hypoxemia, tachycardia, hypotension, pneumonia.
Diagnosed through a chest x ray (it shows no sharp edges of the lungs, dark shadow is not seen as much) , base of the lung sounds and ABG symptoms
treatment- early mobilisation, chest physiotherapy, coughing and deep breathing, positive pressure ventilation, antibiotics.

Question 8

Describe characteristics of hypoxia (diagnosis, manifestations, pathophysiology, treatment)

Answer 8

• Low blood tissue oxygen level > can result in tissue hypoxia where tissue cells die which is a significant problem
• Common condition in many post operations
• Often combined with atelectasis
• Causation: hypoventilation, V/Q mismatch
• Pathophysiology:
○ Decreased minute ventilation
○ Shunting of gas volume from under ventilated alveoli
○ Decrease in gas volume to under perfused alveoli

        Diagnosis: clinical presentation, oxygen saturation, ABG

        Treatment: REVERSE CAUSE, supplement oxygen, positioning, positive pressure ventilation

Question 9

Explain pleural effusion (diagnosis, pathophysiology, treatment, signs)

Answer 9

• Fluid in the pleural space: common in thoracic and upper abdominal surgery (can cause atelectasis)
  
  • 2 types: transudative (water and protein poor) and exudative (protein rich)
  • Causation: imbalance between fluid production and removal, inadequate lung expansion, disruption to pleural membrane
  • Clinical signs: cough, dyspnoea, pleural friction, decreased in breath sounds
  • Diagnosis: chest x ray,
  • Treatment: if patient is active is resolves usually, chest physiotherapy, oxygen therapy (if not resolved)

Question 10

Describe Pneumonia (diagnosis, treatment, signs)

Answer 10

• Occurs within 5 days of surgery
  
  • Signs: Fever, leucocytosis, increased secretions, pulmonary infiltrates on chest xray
  • Diagnosis: controversial- generally all patients suspected with x ray infiltrates
  • Difficult because many other conditions similar- atelectasis and pulmonary oedema
  • Treatment: oxygen, analyse cultures, chest physiotherapy, positioning, positive airway pressure

Question 11

Explain respiratory and metabolic acidosis/alkalosis.

Answer 11

○ Metabolic acidosis= PaCO2 and HCo3 decreased
○ Respiratory acidosis the opposite ^

	○ Respiratory alkalosis = PaCO2 and HCo3 decreased 
	○ Metabolic alkalosis opposite

Question 12

What are you assessing when auscultating breath sounds ?

Answer 12

• character of breath sounds
• presence of abnormal (adventitious) sounds
• character of spoken/whispered voice

Question 13

What are normal breath sounds and where are they heard?

Answer 13

> Tracheal (heard over the trachea): the breath sounds are harsh and sounds like air being blown through a pipe.

> Bronchial (large airways in the anterior chest near the 2nd and 3rd intercostal space): not as harsh as tracheal, more tubular and hollow sounding, loud and high pitch with a short pause, expiratory sounds last longer than inspiratory.

> Broncho-vesicular (heard in the centre part of the 1st and 2nd intercostal spaces, anterior chest- need to know normal sound of this): softer than bronchial, equal inspiration/expiration, abnormalities in pitch and intensity are often more easily detected.

> Vesicular: (between 4th and 5th intercostal): soft blowing or rustling sounds, normally throughout inspiration, may be harsher in children, elderly, obese, and muscular people.

Question 14

What are two types (two main ones) of adventitious breath sounds?

Answer 14

> Crackles: consolidation of fluid or sputum, air moves abnormally through airways (vibrating with fluid)

> Wheeze: high pitch, airway narrowing (e.g. asthma)

Question 15

Describe management of post operative respiratory complications.

Answer 15

> adequate and systematic pre-operative assessment (history, their surgery, the disease process, patient status)
identify high risk patients: exisiting pulmonary disease, airway complications, previous post-operative pulmonary complications
Lung protection ventilation: lower volumes improved patient outcomes