You are called to urgently review a 70-year-old patient who is being ventilated following admission with severe community-acquired pneumonia. She had a tracheostomy five days ago. She has now acutely desaturated with a saturation of 85% and developed high airway pressures but is haemodynamically stable.
Outline your differential diagnosis and initial management of this problem.
This question is essentially the same as Question 12 from the first paper of 2015, except the patient has aged three years over t, and is now 73. Bewildered, the author could only guess at the significance of this minor change.
A good algorithm for assessing a patient suddenly impossible to ventilate is suggested in Chapter 3 of Emergency Department Resuscitation of the Critically Ill, "The Crashing Ventilated Patient" by Jairo Santanilla.
The following approach has been adopted from the above.
- Increase the FiO2 to 100%
- Disconnect from the ventilator, and manually bag-ventilate them.
- Simultaneously assess and manage threats to life in a systematic manner.
- If the lung compliance is good, the patient's ventilator or its tubing is the problem, and you can keep bagging the patient until the ventilator is changed.
- if the bag ventilation is difficult, one must conclude that the patient or the tube are the problem.
If the bag ventilation is easy and the patient improves with it:
- Machine factors are to blame.
- Check the circuit:
- Check for condensation in the ventilator tubing
- Change HME
- Change the expiratory filter
- If there is nothing obviously wrong with the tubing, the ventilator may be malfunctioning. Change the ventilator while manually bagging the patient.
If the bag ventilation is difficult and the patient is still unwell:
- Patient factors are to blame.
- Either the airway or the rest of the respiratory system is somehow compromised.
- Address the airway first:
- In the intubated patient:
- Is the ETT blocked?
- Pass a suction catheter down and suction the patient
- Ensure the patient is not biting the tube.
- Has the ETT migrated? Is there a cuff herneation?
- Auscultate both lungs; ensure equal air entry
- Listen for cuff leak
- Ensure satisfactory cuff pressure
- In the tracheostomy patient:
- check tracheostomy diameter (too narrow?)
- check inner cannula (encrusted with inspissated secretions?)
- check tracheostomy patency (blocked with secretions?)
- Check tracheostomy position (dislodged during last turn?)
- Check for subcutaneous emphysema
- Suction the patient, loking for fresh blood and clots (unrecognised pulmonary haemorrhage?)
- Let's say the airway is fine. The rest of the respiratory system must be somehow compromised. The possibilities include:
- Bronchial occlusion, eg. by sputum plug or clot
- Pulmonary embolism
- Pulmonary oedema
- Pleural pathology, eg. pneumothorax, haemothorax or pleural effusion
- Abdominal pathology, eg. massive distension
- These possibilities need to be investigated systematically:
- Auscultation of the chest will immediately identify lateralising pathology, and may reveal pulmonary oedema
- A bedside chest ultrasound will immediately confirm or exclude pneumothorax, haemothorax or large pleural effusion.
- A bedside TTE should immediately exclude severe LV failure and massive PE.
- ECG will exclude MI
- ABG will identify metabolic acidosis
- CXR to confirm/exclude large bronchus obstruction
- Bronchoscopy to relieve this mechanical obstruction
- If there is no problem with the respiratory system, but the patient is still "impossible to ventilate", consider the following extrapulmonary possibilities:
- Patient-ventilator dyssynchrony
- Pain of respiration (eg. in context of rib fractures or thoracotomy)
- Increased ventilatory demand:
- Severe agitation
- Fever and rigors
- Metabolic acidosis