You are called to urgently review a 73-year-old female who is ventilated following admission with severe community-acquired pneumonia. She had a tracheostomy five days ago. She has now acutely desaturated and developed high airway pressures.
Outline your management of this problem.
This is an emergency situation with the risks of hypoxia, hypoventilation and/or barotrauma.
Management consists of concurrent resuscitation and focussed assessment to identify the underlying cause with definitive management as indicated.
The differential diagnosis includes:
- Ventilator malfunction
- Obstruction/kinking of circuit including filter
- Displacement/blockage trache tube
- Increased airway resistance e.g. bronchospasm
- Decreased lung or chest wall compliance e.g. pneumothorax, lung collapse, intra-abdominal hypertension
Stepwise response (does not have to be in this order)
- Increase FiO2 to 1.0
- Assess patient for severity of insult – is there haemodynamic instability? Is the patient peri-arrest?
- Call for help and crash trolley / difficult airway trolley if indicated
- Disconnect patient from the ventilator and manually ventilate with FiO2 1.0 and assess resistance/compliance
- If resistance/compliance seems normal with reduction in airway pressures and improvement in saturations
then cause is due to ventilator malfunction or inappropriate settings. Replace ventilator and/or review settings
- If resistance/compliance seems abnormal then systematic approach to look for cause
- Check circuit and filter for kinking/blockage and unkink/replace as indicated
- Assess trache for position and patency – remove inner cannula and pass suction catheter. If not patent and
not cleared by suction or if displaced (may be evidence of subcutaneous emphysema) remove trache tube, occlude stoma and ventilate initially with bag-valve-mask and subsequently re-intubate with oral endotracheal tube
- If trache tube patent and correctly placed assess chest expansion and air entry to confirm/exclude bronchospasm, pneumothorax, lobar collapse, pleural effusion etc.
- Treat as appropriate – bronchodilators, thoracocentesis, physio, bronchoscopy, pleural drainage
- If decreased chest wall compliance consider sedation
- If increased intra-abdominal pressure, treat appropriately e.g. gastric decompression
- Re-assess patient after definitive management with investigations as indicated e.g. ABG and CXR.
- Be aware there may be more than one cause.
If there is an obvious precipitating cause e.g. pneumothorax complicating difficult CVC insertion, tracheostomy displacement then treat this directly but then re-assess patient for resolution of hypoxia and high airway pressures
Candidates were expected to describe a systematic approach and consider the possibility of multiple causes
Contrary to the above comment, some of these steps do have to be in order. A good algorithm 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