Pneumothorax Flashcards
pré scan?
Probe(s)
Linear / curvilinear / phased array.
Knobology
Dive the depth to centre all relevant anatomy.
Recommended starting depth for beginners: 10 cm in adults. Initial depth for pediatric patients varies with age.
Beginners should always set the initial depth deep enough to avoid missing relevant anatomy. With experience, initial depth should be adjusted to account for patient body habitus.
Gain = mid-range.
System preset(s) = lung, abdominal.
Patient positioning
Supine.
Patient draping
Anterior chest exposed.
Probe orientation
Probe held perpendicular to the floor / stretcher with the beam directed towards the patient’s back and the probe marker oriented towards the patient’s head.
Probe grip
Probe held softly between thumb and 2-3 fingers close to the probe face, one to two fingers on patient to enhance proprioception (same as OB longitudinal).
repère externe?
External landmark
Most anterior part of lung in the mid-clavicular line of a supine patient.
repèere interne?
Internal landmark
Ribs and rib shadows.
zone d’intérêt?
Area of interest(s)
Pleural line.
position patient?
supine
anatomie?
Ribs and rib shadows, lung, pleura, diaphragm, liver / spleen, heart, stomach.
technique et définition ligne pleurale?
Pleural line (lung sliding, comet tails, lung pulse):
Definitions:
Lung sliding: Visceral and parietal pleura moving against each other with respiration.
Comet tails: A short white line arising from the pleura line caused by reverberation of the ultrasound beam between the visceral and parietal pleura.
Lung pulse: Cardiac pulsations transmitted to the pleural line in a poorly aerated lung (i.e., atelectasis or main stem intubation).
The presence of lung sliding, comet tails, or a lung pulse rules out a pneumothorax at the intercostal space being interrogated.
To assess the lungs for a pneumothorax a CPoCUS-IP must:
Start the scan by placing the probe at the most anterior (least gravity dependent) part of the chest in the mid-clavicular line. The probe marker is oriented towards the head of a supine patient.
Identify the ribs and acoustic shadows.
Slide the probe cephalad or caudad to place one rib on either side of the screen.
Identify the pleural line between and far field to the ribs.
Sweep the probe from side to side to generate the clearest image of the pleura (i.e., beam hitting pleura at 90 degrees).
Assess the pleural line for the presence of lung sliding, comet tails or a lung pulse. Simultaneously optimize depth and gain to centre the pleural line and prevent over or under gaining.
If no lung sliding or lung pulse is immediately visible, the pleural line should be assessed for a minimum of 3 respiratory cycles. The probe should be held as still as possible during this assessment.
Repeat these steps at alternate pleural lines in at least two other intercostal spaces (three in total) in each hemithorax by sliding the probe cephalad or caudad. Step 5 should be repeated each time the probe is moved to a new intercostal space to optimize the view of the pleural line.
Identify the physiologic lung points in each hemithorax (liver lung point and cardiac lung point). The splenic lung point and the gastric lung point might also be visible in the left hemithorax, but their identification is not a required skill for CPoCUS certification.
technique et définition ‘‘lung point’’?
Lung point:
If lung sliding, comet tails, and lung pulse are not visible in one or more intercostal spaces for at least 3 respiratory cycles AND the patient is stable*, a lung point must be identified to declare a pneumothorax:
The probe is placed at the anterior axillary line with the marker oriented towards the patient’s head.
If lung sliding or comet tails are not visible, the probe is moved to the mid-axillary line.
If lung sliding or comet tails are still not visible, the probe is moved to the posterior axillary line.
If lung sliding is identified at any point, the probe is slid slowly back towards the sternum (i.e. anteriorly and medially) until a lung point is identified.
The location of the lung point can be used to estimate the size of a pneumothorax in the supine patient. In general, the closer the lung point is to the posterior axillary line, the larger the pneumothorax. The closer the lung point is to the sternum, the smaller the pneumothorax.
Approximate size of pneumothorax, in a supine patient, based on location:
Small – lung point located anteriorly (i.e. between mid-clavicular and anterior axillary lines). Medium – lung point located laterally (i.e. mid-axillary line).
Large – lung point located posteriorly (i.e. posterior axillary line).
IMPORTANT: A very large pneumothorax may not have an identifiable lung point as normal lung is often not be visible using PoCUS at the chest wall in such cases.
- If no lung point is identified and patient stability* permits, a confirmatory test must be performed (CT scan or upright chest x-ray).
*instability might include abnormal vital signs, multi-system trauma, or suspicion of a pneumothorax that requires immediate intervention (i.e. tension pneumothorax) but the definition of clinical stability is always at the discretion of the treating clinician.
quels lung point faut-il trouver puor la certification?
foie
coeur
qu’est-ce qui est 100% pathognomonique d’un PTX?
un lung point patho (no sliding)
troubleshoot?
Lung sliding questionable (comet tails and lung pulse absent):
1. Sweep probe to ensure beam is perpendicular to the pleura.
- Decrease depth to magnify pleura.
- Decrease gain. Over-gaining is a very common problem at shallow depths and will “wash out” lung sliding. This occurs especially with the curved array probe.
- Adjust probe frequency. A higher frequency will allow better resolution of a shallow pleural line.
- Rotate probe to elongate pleura. Once the pleura is identified, the probe can be rotated so that the beam is parallel to the ribs. This will elongate the image of the pleural line on the screen, allowing a larger portion of the pleura to be evaluated for lung sliding.
- Change to linear probe. If using the curved array probe, switch to this higher frequency probe to see the pleura more clearly.
Differentiating physiologic from true lung point:
- Increase depth. This will allow you to appreciate the solid organ tissue (liver, spleen, heart) better on screen right.
pitfalls images interpretation
Pitfalls (Image interpretation)
False positive scans:
1. Declaring a pneumothorax based solely on the absence of lung sliding in one of the following conditions:
Right mainstem (single lung) intubation. The identification of comet tails and/or a lung pulse can help prevent this pitfall.
Esophageal intubation in an apneic patient. Lung sliding will not be seen but a lung pulse and comet tails should still be visible.
Esophageal intubation in an apneic patient AND in cardiac arrest. Lung sliding or a lung pulse will not be seen but comet tails should still be visible.
Phrenic nerve palsy. Will cause isolated absence of lung sliding but lung pulse and/or comet tails should still be visible.
Conditions where the visceral and parietal pleura are adherent to each other. This includes ARDS and chronic pleurodesis such as localized adhesions from previous chest tube insertions, previous surgical pleurodesis or adhesions from cancer.
-Pulmonary fibrosis. A lung pulse and/or comet tails are usually easily seen in these patients.
Large pulmonary infiltrates. The pleura is often not visible.
Pleural effusions. No pleura should be visible.
Severe COPD causing bulla formation. No pleura should be visible.
Pulmonary contusions. Absence of lung sliding is common with this type of trauma but comet tails are usually quite evident.
2. Mistaking a physiologic lung point for a true lung point. Includes the liver and cardiac lung points but may also include areas where the left lung intersects with the stomach (aka gastric lung point) or the spleen (aka splenic lung point). Remember that physiologic lung points always have lung sliding next to organ sliding (i.e. liver, heart, etc.) whereas pathologic lung points have lung sliding next to nothing sliding.
pitfalls faux nég
False negative scans:
Large pneumothorax. Patients with a very large pneumothorax (greater than 65%) are likely to have no normal lung tissue touching an accessible part of the pleura in a supine patient. A lung point would therefore not be found.
Misidentifying movement at the pleural line due to poor hand control (i.e. shaking) as lung sliding or a lung pulse.
pitfalls génération d’image?
Pitfalls (Image generation)
Sweeping too quickly.
Not interrogating the pleura at 90 degrees.
Not keeping the probe steady.
Poor probe control / grip.
Too much or too little gain. Too much gain is the more likely pitfall and will often “wash out” lung sliding.
Pleura not centered / depth not minimized.
Not waiting at least three respiratory cycles if lung sliding and/or lung pulse are not seen immediately.
Failure to interrogate the pleura in at least three intercostal spaces in each hemithorax.
pitfalls intégration clinique
Pitfalls (Clinical integration)
Treating for a pneumothorax (i.e. placing a chest tube) based on a false positive scan (see Image interpretation pitfalls).
Treating a very small pneumothorax that is clinically insignificant. This error can occur if the size of the pneumothorax was not estimated based on lung point localization (or with a confirmatory test), resulting in the erroneous diagnosis of a large pneumothorax. It can also occur if a small pneumothorax was detected with lung point localization (or a confirmatory test) but the incorrect approach was taken that all pneumothoraces regardless of size require treatment. Note that if the patient requires mechanical ventilation, prolonged ground transfer, or air transfer, even a small pneumothorax may require prophylactic chest tube placement.
Failure to treat a patient with a strong clinical suspicion of a pneumothorax based on a false negative scan (see image interpretation pitfalls). This most commonly occurs with a very large pneumothorax that has a lung point not accessible with PoCUS. A confirmatory test (i.e., upright chest x-ray or CT scan) should be obtained to rule out or confirm a very large pneumothorax if a lung point cannot be found or the patient should be treated empirically, without a confirmatory test, if they are unstable and have a strong clinical suspicion of a pneumothorax (i.e. suspected tension pneumothorax).
Failure to treat a patient with a strong clinical suspicion of a pneumothorax based on an indeterminate scan. Significant subcutaneous emphysema might occur with a large pneumothorax and this air will limit the ability of PoCUS to identify landmarks and the pleura. A confirmatory test (i.e., upright chest x-ray or CT scan) should be obtained to rule out or confirm a very large pneumothorax if the pleura cannot be visualized or the patient should be treated empirically, without a confirmatory test, if they are unstable and have a strong clinical suspicion of a pneumothorax (i.e. suspected tension pneumothorax).
