One Lung Ventilation Flashcards
(7 cards)
What are the absolute indications for one lung ventilation
To isolate a diseased lung and prevent contamination of the healthy lung e.g. empyema or massive haemorrhage
To control the distribution of ventilation e.g. for bronchopleural fistula, major cyst, bullous disease or traumatic bronchial injury
For unilateral lung lavage, for example, in the treatment of alveolar proteinosis or cystic fibrosis
What are the relative indications for one lung ventilation?
Thoracic surgery, e.g., for lobectomy, pneumonectomy, lung volume reduction surgery, and video-assisted thoracoscopic surgery (VATS).
Thoracic aortic aneurysm surgery
Oesophagectomy
Mediastinal Mass Surgery
Minimally invasive cardiac surgery
What specific indications are there for the placement of a right-sided double lumen tube
Surgery involving the left main bronchus, e.g., left pneumonectomy, left lung transplant, left trachobronchial disruption
Distortion of the normal anatomy of the left main bronchus, for example, aneurysm of the descending thoracic aorta, tumour compressing the left main bronchus
N.B, most procedures can be facilitated by a left double lumen tube, which is easier to position
What are the disadvantages of using a double-lumen tube
Significantly larger, also more rigid than a standard endotracheal tube and hence an increased risk of airway and or oral trauma
Difficult to insert in a patient with a difficult or distorted airway
Potential need for airway exchange to a single lumen tube at the end of a case, if ongoing post-operative ventilation is required.
Movement or dislodgement of the tube with subsequent failure of lung isolation
How can the risks associated with lung resection be quantified preoperatively
Assessment of the likelihood of postoperative dyspnoea is estimated by performing lung function tests and calculation of the predicted postoperative (PPO) FEV1 and the diffusing capacity of the lungs for carbon monoxide (DLCO) based on anatomic calculations. I.e., calculating the predicted remaining FEV1 and DLCO based on the preoperative measurements and the proportion of the 19 segments that are to be removed. Patients with PPO FEV1 or DLCO less than 30% of predicted are at a high risk of postoperative dyspnoea and need for long-term oxygen and require a formal functional assessment before proceeding.
Functional assessment for higher risk patients e.g. CPEX testing VO2 peak being the most useful measure with <10ml O2/min/kg being a contraindication and > 15 being “good physiological reserve” and > 20 being safe for pneumonectomy. Stair climb, shuttle walk test and 6 minute walk test are other functional assessments that can be performed.
Specific Mortality risk prediction scores for lung surgery, such as RESECT-90 and Thoracoscore, they incorporate factors such as performance status, symptoms, age, sex and co-morbities and are generally poor predictors of risk.
Specific assessment of perioperative cardiac risk with a risk prediction model, e.g. Thoracic Revised Cardiac Risk Index
Assessment of pre-existing pulmonary hypertension with echocardiogram as this will be exacerbated by halving the pulmonary vasculature with a pneumonetomy
How can you improve hypoxaemia resulting from one lung ventilation
Call for Help
Increase FiO2 to 100%
Airway:
Take over manual ventilation of the patient to assess compliance
Check for obvious equipment failure such as a disconnection
Check for double lumen tube or bronchial blocker dislodgement
Check for secreations or blood that may have occluded the tube
Bronchoscopy and repositioning of the double lumen tube / bronchial blocker if the position has slipped, and clearance of secretions as necessary
Breathing:
Assess for compliance, capnography, waveform, oxygen saturations
Auscultate the chest (if feasible whilst the patient is draped)
Consider: Bronchospasm, Pneumothorax (of the ventilated lung), Inadequate paralysis
Perform recruitment maneuvers to ventilated lung (may cause transient hypotension and worsening of hypoxemia if more blood is diverted to the non-ventilated lung)
Increase PEEP to the ventilated, dependent (if in the lateral position) lung to counteract the effect of mediastinal weight on the functional residual capacity in the lateral decubitus position.
Decrease PEEP to the ventilated lung to reduce possible compression of the pulmonary capillaries by excessive intra alveolar pressure
CPAP to the non-ventilated lung to reduce the shunt effect caused by ongoing perfusion to the non-ventilated lung
Intermittent two-lung ventilation
Circulation:
Assess for cardiovascular stability; check for sources of bleeding
Ensure haemodynamic stability, giving fluids, vasopressors or inotropes as appropriate
If the surgery is for pneumonectomy, early clamping of the pulmonary artery will resolve shunt issues.
What factors can lead to the development of high airway pressures during one lung ventilation
Mechanical factors:
A double lumen tube is narrower than a standard endotracheal tube
Double lumen tube is more readily obstructed with secretions or blood due to the narrowness of its channels
Double lumen tube malpositioning resulting in loss of airway patency or advancement into a more distal airway
Inappropriate ventilation e.g. excessive tidal volumes (when considering that only one lung is being ventilated)
External compression of the breathing circuit
Patient Factors:
Atelectasis of ventilated lung
(which is exacerbated by dependant position if the patient is in the lateral position for the lung surgery)
Pre-existing lung disease which may be what has necessitated the surgery
Obesity
Failure to maintain adequate muscle relaxation
Acute Events:
Simple or tension pneumothorax
Anaphylaxis
Bronchospasm
Development of acute lung injury due to prolonged surgery or one lung ventilation
