Download mechanical ventilation

Mechanical
Ventilation
Tariq Alzahrani M.D
Assistant Professor
College of Medicine
King Saud University
Anatomy
Apex
-5
Base
Chest
Wall
-8
Lung has weight
Ppl = -2
Mechanical Ventilator
•
•
•
•
•
•
•
•
•
Definition
Indication
Types
Classification
Modes
Goals
Monitor
Weaning
Complication
Indication
• Support of oxygenation
–Oxygen responsive hypoxemias
• Pneumonia
• Sepsis
• Inhalation injury
–Oxygen refractory hypoxemias
• Atelectasis
• Aspiration / Drowning
• Adult Respiratory Distress Syndrome (ARDS)
• Support of ventilation
–Airway compromise
–Muscle fatigue / weakness
–Paralysis / spinal cord injury
–Neuromuscular disease
–Chest wall injury
Types
• Non invasive Ventilation
• Invasive Ventilation
ETT
tracheostomy
Classification
• Volume controlled ventilation
• Pressure controlled ventilation
• Time controlled ventilation
Modes?
AutoFlow
Auto Mode
VS
PPS
PCV
Modes
•
•
•
•
•
•
CMV
AC
PCV
SIMV
PSV
Spo. V
Goals
• Maintain patient comfort
• Allow a normal, spontaneous breathing
pattern whenever possible
• Maintain a PaCO2 between 35-50 mmHg
• Maintain a PaO2 sufficient to meet cellular
oxygen demands but avoid oxygen toxicity
• Avoid respiratory muscle fatigue and
atrophy
PATIENT COMFORT SCALE
Synchronized
Intermittent
Spontaneous Mechanical
Ventilation
Breathing
Controlled
Mechanical
Ventilation
-
+
Pressure
Support
Ventilation
Assist
Control
Ventilation
Pressure
Control
Ventilation
SEDATIVES , ANALGESICS AND MUSCLE RELAXANTS
Monitor
Weaning
• Factors to consider:
•
•
•
•
•
•
•
•
Awake, and off sedation (as much as possible).
Adequate nutrition, fluid status.
Free of infection.
Hemodynamically stable (preferably off pressors, angina controlled, no
active bleeding)
Normal acid-base status
Bronchospasm controlled
Normal electrolyte balance
Oxygenation (O2 requirements <0.5 and PEEP <5 cmH20)
• Weaning Parameters:
•
•
•
•
Inspiratory negative pressure of -25 cmH2O
RR<30
Vt >6-8 ml/Kg
ABG status near normal
Causes of failure to wean:
1. Hypoxemia
• Diffuse pulmonary disease
• Focal pulmonary disease (Pneumonia)
• Pulmonary edema (removal of positive pressure can increase
preload and lead to worsening heart failure)
2.Insufficient Ventilatory Drive:
• response to metabolic alkalosis
• Inadequate function of CNS drive (Ex: sedatives, malnutrition)
3. Excessive Ventilatory Drive:
• Excessive CO2 production (sepsis, agitation, fever, high
carbohydrate intake)
4. Respiratory Muscle Weakness:
• Neuromuscular disease
• Malnutrition
• Drugs (Neuromuscular blocking agents,
Corticosteroids,aminoglycosides)
5. Excessive Work of Breathing:
•
•
•
•
•
•
Airway obstruction
Bronchospasm
Secretions
Increased Raw (ETT)
ETT too small
Chest motion restriction (pain, bandages)
6. Acid base disorders
7. Phrenic nerve Injury
(especially with contralateral pulmonary disease)
Complication
Ventilation-related complications:
• Disconnection
• Malfunction
Hemodynamic effects:
decreased cardiac output due to impaired venous return to the right
heart and increased pulmonary venous resistance due to positive
pressure alveolar distension
AutoPEEP
• Barotrauma or Atelectasis
• Oxygen toxicity
• Respiratory alkalosis
• Increased intracranial pressure
Suctioning-related complications:
• Hypoxemia
a) patients should always be pre-oxygenated with 100% oxygen prior
to suctioning
b) suction time should be limited
• Arrhythmias
• Nosocomial infections
Non-invasive ventilation
• Invasive vs. Non-invasive ventilation
Invasive
 Good control of airway
 Suitable for higher pressures
Non-invasive




Avoidance of complications of intubation
Avoidance of complic of invasive ventilation ( sinusitis…)
If tolerated, more comfortable to awake pts. Breaks possible
No sedation (or less sedation)
Indication
– Acute settings
– Chronic disease
Goals
•
•
•
•
•
Relieve symptoms
Reduce work of breathing
Improve gas exchange
Minimize risk
Avoid intubation
Exclusion criteria
1.Respiratory arrest
2.Medically unstable
3.Unconscious, unable to protect airways
4.Excessive secretions
5.Significant vomiting
6.Agitated or uncooperative
7.Facial trauma, burns, surgery or anatomic
abnormalities interfering with mask
application