Presentation

• Difficult to ventilate
Decreased compliance in reservoir bag, poor chest expansion, low minute volume
• High airway pressure/ alarm
• Abnormal CO2 trace
Up sloping- bronchospasm
Low- reduced cardiac output
• Hypoxia
• Circulatory collapse
Occluded expiratory limb, tension pneumothorax, anaphylaxis

Initial response

• Check patient+ review environment
ABC
Oximeter, capnograph
Machine + circuit
Surgical activity
Hand ventilate 100% oxygen 
• Exclude obvious causes
Fighting ventilator- not paralysed
Closed expiratory limb- ballooning of reservoir bag
Excessive tidal volumes/ ventilator settings
Kinked tubing

Consider context

• Position- prone, trendelenburg
• Pre-existing disease- asthma, obesity, ARDS
• Timing of event- post cvc
• Prior events
• Risk factors- allergy
• Surgery- laparoscopy + pneumoperitoneum

Systematic review

• Anaesthetic circuit
Check with alternate circuit i.e. ambu bag
• Endotracheal tube
Kinked?
Position at lips?
Obstructed? Rx. deflate cuff pass suction catheter
• Low threshold to change tube!

Causes

• Common problem
• Potentially life threatening
• Requires systematic approach after exclusion obvious and common causes

Non Patient Problems

• Gas supply
O2 flush stuck on
High pressure gas source
• Circuit
Blockage, compression, kinking or incorrect connection of:
Scavenging, reservoir bag, filter, humidifier
APL valve, PEEP valve
Ventilator, angle piece, tube connector
Breathing hoses + valves etc
Excessive tidal volumes

Non Patient Problems

• Endotracheal Tube
Kinked
Misplaced
Oesophageal
Endobronchial
Obstructed
Sputum, blood …
Cuff herniation
Too small

Patient Problems

• decreased chest wall compliance
Chest wall rigidity
MH or opioids
Prone/ position
Obesity
Kyphoscoliosis
Abdominal pressure
distension
laparoscopy
gastroschisis repair
Inadequate paralysis/ fighting ventilator
• decreased lung compliance
Pneumothorax/ haemothorax
Atelectasis
Pulmonary oedema
>Fibrosis
ARDS 
• increased airway resistance
Bronchospasm
Foreign body
Anaphylaxis/ anaphylactoid
Aspiration
Amniotic fluid embolism