Week 3 (A) Effects of Intubation and PPV on the cardiorespiratory system Flashcards
Problems with intubation
- Increases airway resistance
- Impairs secretion clearance (Decreases MCC)
- Impairs secretion clearance (cough)
- Increased risk of trauma to airway
- Increased risk of infection
- Increase in non gas movement area
Why is increased airway resistance a problem with intubation
– Endotracheal tube (length, radius)
– Reflex bronchospasm (immediate)
– On inspiration = increased load (for spontaneous
breaths)
Why is impaired secretion clearance a problem with intubation?
• Impairs secretion clearance (Dec. MCC)
– Decrease ciliary action
– Prolonged intubation
– Decrease in humidification – sol layer
• Impairs secretion clearance (cough)
– Less effective (no glottic closure)
– Slower EFR (TPLGF)
– Decreased secretion movement ‐ Increased Raw
Why is there an increased risk of trauma to airway with intubation?
– Direct trauma – stenosis/fistula
– Abrasion of mucosa
– Pressure necrosis
Why is there an increased risk of infection with intubation?
– Normal defence mechanisms bypassed
– Nosocomial pneumonia (ventilator associated
pneumonia VAP)
Why is there an increase in non gas movement area with intubation?
(Increased deadspace ‐ issue for spontaneous breaths)
– ETT and tubing from ventilator
Intubation: implication for physio
Minimise the effects of intubation • Remove secretions • Time with bronchodilator ( gas movement) • Careful handling of ET tube/head & neck movement • Take care with suction • Sterile technique • Non traumatic • Cuff check: inflated/pressure • Past medical history – awareness
Different effects PPV can have
Physiological insult
Pulmonary Consequence
Cardiovascular consequences
What does PPV stand for
Positive Pressure Ventilation
Pulmonary effects of PPV
Lung volumes • Dec. compliance of lung (CL) – Monotonous pattern / no sighs – Dec. FRC • Dec. FRC due to: – Decrease in volume (microatelectasis) – Cephalad displacement of diaphragm = less air to dependant regions
Distribution of ventilation
• Ventilation to non‐dependant regions
– airway resistance less in these regions
Strategies to overcome pulmonary effects of PPV
• Strategies: PEEP
– Decreases Raw
– alveolar emptying thus alveolar size/number
( FRC) which surface area esp. in dependant
well perfused areas
– May increases spontaneous VT / sigh which
promotes stretch/surfactant production
Physiological insults of PPV
• Ventilator induced lung injury (VLI)
Oxygen toxicity
How is PPV administered
Paralysed. Neuromuscular blocking agent - cannot take a breath
Cardivascular effects of PPV
IPPV + PEEP
+ve intrathoracic pressure
“squashing effect”
compared to
Spontaneous breathing
‐ve intrathoracic pressure
“sucking effect”
Medical management of Cardiovascular effects of PPV
• Medical management: fluid / inotropes (increase contractility of the heart)
Name some inotropes
addrenaline, noradrenaline, dopamine
Overall summary of effects of PPV
- Change in distribution of ventilation
- Dec. compliance of lung (CL)
- Dec. FRC therefore O2 movement
- Barotrauma/Volutrauma
- O2 toxicity
- Dec. venous return which cardiac output
- Dec. alveolar perfusion which O2 movement
Respiratory muscle deconditioning
• < 48 hours
Rest muscles
Repairs muscle fibres
Normalisation of ABG
Respiratory muscle deconditioning
> 48 hours
• Decrease diaphragm strength • Decrease in RM endurance • Deconditioning • ↓ type I fibres • ↓ sarcomere numbers • ↓ capillaries • ↓ myoglobin • ↓ oxidative enzymes ↓ length / & altered length ‐ tension
Effects of immobilsation MSK
- Peripheral muscle wasting and shortening
- Joint changes
- Bone demineralisation
Effects of immobilsation CVS
- Dec. blood volume
- Dec. Hb
- Venous stasis (DVT, PE)
Effects of immobilsation Metabolic
• Inc. excretion of nitrogen, calcium, potassium, magnesium,
phosphorus
• Osteoporosis
• Kidney Stones
