Épanchement pleural Flashcards
préparation préscan
Probe(s)
Curvilinear.
Knobology
Dive the depth to centre all relevant anatomy.
Recommended starting depth for beginners: 15 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) = abdominal/FAST.
Patient positioning
Supine.
Patient draping
Males – Torso exposed.
Females – Towels tucked into bra bilaterally in upper flank/lower axillae, bra possibly pulled up slightly as needed, abdomen exposed.
Probe orientation
Probe held parallel to the floor / stretcher with the beam directed towards the patient’s midline and the marker oriented towards the patient’s head.
Probe grip
Probe cradled, soft hand, probe held close to the probe face, one finger (2nd or 5th) against patient.
Repère externe
External landmark
Posterior axillary line at level of xiphoid.
Repère interne
Internal landmark
Kidney to define interface. Diaphragm to define thorax.
Anatomie pertinente
Relevant anatomy
Liver/Spleen, diaphragm, lung, spine.
zone d’intérêt
Area of interest(s)
Area cephalad to diaphragm, medially (6-9 o’clock), and laterally (12 o’clock).
Technique?
To assess for a pleural effusion a CPoCUS Independent Practitioner must:
1. Start at the intersection of the posterior axillary line and the xiphoid process (i.e. external landmark) and move the probe in the posterior-anterior plane to find the clearest interface between the solid organ and the kidney. The ideal view of the interface is seen at the point where the greatest possible portion of the kidney is seen, and where the kidney’s capsule is at its brightest. The probe is always kept parallel to the stretcher/floor.
- Magnify the image to make the kidney as large as possible on the screen while keeping the spine visible, medial (i.e. far-field) to the kidney.
- From the best possible view of the interface, adjust probe location and orientation, if needed, using a systematic troubleshooting algorithm, to visualize the entire medial aspect of the hemithorax cephalad to the diaphragm (i.e. 6 o’clock to 9 o’clock). This area must be swept anteriorly and posteriorly until the diaphragm disappears in both directions, looking for pleural fluid and/or a spine sign.
A positive spine sign represents the visualization of the thoracic spine above the diaphragm and makes the presence of pleural fluid very likely. The spine is usually not visible in this area due to gas scatter from the lung. Pleural fluid can act as an acoustic window and make the thoracic spine visible, producing an image where the spine is seen as one continuous hyperechoic line, crossing the diaphragm from the abdomen into the chest. - During the sweep, interrogate the hemithorax cephalad to the entire visible diaphragm for pleural fluid, from 6 o’clock up to and including 12 o’clock in some patients, to detect both medial and lateral effusions.
*Above adapted from the PALMS mnemonic, courtesy of Dr. Ray Wiss
Qu’Est-ce que le spine sign?
le fait de voir la colonne à la hateur du thorax (il faut du liquide pleural pour que ce soit possible!!)
Qu’est-ce que signifie de regarder à 12h? ou en latéral? et que signifir la visibilité du diaphragme?
regarder en latéral du patient, c’Est à dire à proximité de la sonde! Soit dans le haut de l’écran!
Si le diaphragme est visible = épanchement très prob
que signifie le signe de rideau?
épanchement bcp moins probable (mais pourrait être petit)
Trucs de troubleshooting?
Troubleshooting
To produce a determinate pleural effusion scan, a CPoCUS-IP must be able to visualize the medial aspect of the thorax cephalad to the diaphragm (i.e. 6 o’clock to 9 o’clock).
The diaphragm can be quite difficult to image adequately, especially in the left hemithorax, and a sequential troubleshooting algorithm is required to efficiently overcome any challenges to diaphragm visualization.
This systematic approach is as follows:
Step 1: Find the best view of the interface/kidney. Using the systemic approach outlined in the technique section, it is imperative that a CPoCUS-IP first find the best view of the interface. This image is generated when the greatest possible portion of the kidney is seen, and where the kidney’s capsule is at its brightest.
This step is the foundation of all other troubleshooting maneuvers for finding the diaphragm and should never be skipped.
An adequate portion of the diaphragm often becomes visible solely by performing this maneuver. If this is the case, the diaphragm should be swept until it disappears in both directions. Otherwise the operator should move to the next step.
Step 2: Moving cephalad in the longitudinal plane. If the entire medial aspect of the diaphragm (6 o’clock to 9 o’clock) is not seen after Step 1 is performed, the probe should be moved in the longitudinal plane towards the patient’s head.
It is important that this only be done after performing Step 1 well.
Sweep the diaphragm if it is adequately visualized. If it is not, move to the next step.
Step 3: Probe rotation. If the entire medial aspect of the diaphragm (6 o’clock to 9 o’clock) is not seen after performing steps 1 and 2 in sequence, the probe should be rotated. This is done to move the probe into intercostal spaces AND to align the probe with the diaphragm (which attaches to the spine obliquely).
As with probe rotation to overcome rib shadows, this maneuver is difficult and best performed with a relaxed hand, optimizing proprioceptive feedback to the operator’s hand. Sweep the diaphragm, with rotation maintained, if it is adequately visualized. If it is not, move to the next step.
Step 4: Moving anteriorly & sweeping posteriorly (OR moving posteriorly and sweeping anteriorly). If not enough diaphragm is visible after performing the first three steps in sequence (best view of the interface, moving cephalad and probe rotation), the operator should move the probe anteriorly one or two intercostal spaces and then sweep the probe posteriorly.
Alternatively, the operator can move the probe posteriorly one or two intercostal spaces and then sweep the probe anteriorly.
These maneuvers should be done with the probe in the same orientation at the end of Step 3 (i.e., rotated) and are designed to enhance the use of the spleen as an acoustic window AND to align the ultrasound beam with the obliquely positioned diaphragm.
Sweep the diaphragm, with rotation maintained, if it is adequately visualized. If it is not, move to the next step.
Step 5: Moving caudad and heeling through the solid organ (liver or spleen). If the portion of the diaphragm which is visible after performing the first four steps is inadequate, the operator should move the probe back to the starting position achieved in Step 1, move the probe caudally in the longitudinal plane and heel the probe cephalad, directing the ultrasound beam through the spleen.
This maneuver is designed to enhance the use of the spleen as an acoustic window but is usually not as effective as the first 4 steps in the left hemithorax. It should, therefore, be kept as the last troubleshooting maneuver to be attempted on the left.
The liver, on the other hand, provides such a good acoustic window that Step 5 should be the first troubleshooting maneuver used to visualize the diaphragm on the right.
Troubleshooting avec la rate? quelle méthode?
vs le foie?
rate:méthode du cornet de crème glacée
foie: bouger longitudinal vers caudal et pointer vers la tête
Pitfalls interprétation d’image
Pitfalls (Image interpretation)
False positive scans:
Mistaking mirror artefact of the solid organ (most commonly the liver) for a pleural effusion. This error can be avoided by identifying mirrored blood vessels within the presumed effusion and the lack of a spine sign.
Mistaking the dark gas scatter from lung tissue for a pleural effusion. This error can be avoided by properly identifying the spine in the abdomen and recognizing the lack of a spine sign.
False negative scans:
Missing a pleural effusion in the presence of an empyema or delayed trauma with clotted blood.
pitfalls intégration clinique?
Pitfalls (Clinical integration)
Placing a chest drain because of a false positive pleural effusion scan (see Pitfalls-Image interpretation).
Assuming that a large pleural effusion cannot cause hemodynamic compromise. Obstructive shock might result from ‘tension’ pleural effusions that are very large or rapidly accumulating. Hypovolemic shock can be caused by significant blood loss into the thorax in trauma. Prompt chest drainage would be warranted in these situations.
pitfalls génération d’images?
Pitfalls (Image generation)
Sweeping too quickly.
Probe marker oriented incorrectly (i.e. caudally).
Starting the scan too anteriorly.
Not finding the point at which the greatest possible portion of the kidney is seen, and where the kidney’s capsule is at its brightest.
Gripping the probe too tightly.
Holding the probe incorrectly
Moving the probe in more than one plane at a time (i.e. moving anteriorly or posteriorly while attempting to move only longitudinally).
Following the contour(s) of the patient. Following the contour(s) of the patient. This happens when the probe is held perpendicular to the patient rather than parallel to the floor while moving anteriorly or posteriorly. It can also occur when moving longitudinally if the operator heels or toes the probe rather than keeping the centre of the probe against the body.
Dropping the handle of probe (often occurs when reaching across the patient’s body to scan the opposite upper quadrant).
Moving the probe face while sweeping (i.e. ‘painting’).
Over-rotating the probe.
Rotating in the wrong direction.
Using diaphragm troubleshooting techniques in the wrong sequence. These maneuvers must be done in the correct order.
Asking the patient to take a deep breath to bring the diaphragm closer to the probe.
tips and tricks
The hand should be thought of as a platform upon which the probe gently rests. The thumb’s primary function is to control sweeping and rotating. There is no reason to squeeze the probe tightly for this scan.
Imagine that the patient is a cardboard box. This means the probe should not follow body curves:
Always keep the probe parallel to the floor while sliding it, and not perpendicular to the patient.
Avoid heeling the probe along body contours while moving in the longitudinal plane.
Scan in only one plane at a time. When exploring the longitudinal plane, the kidney should only change in position, not change in shape or size. If it does change in shape or size, the probe has moved off the longitudinal plane (i.e. moved anteriorly or posteriorly to some extent).
Sweep with the probe face fixed to the side of the patient. Do not “paint” the side of patient with the face of the probe while sweeping.
Rotate the probe marker, which should be pointing cephalad, towards the back of the armpit to get between the ribs.
Relaxing the hand holding the probe will markedly improve proprioceptive feedback, allowing the operator to “feel” the probe go between the patient’s ribs during rotation. The diaphragm must always be used to define the end-points of sweeping for a pleural effusion.
Always follow the systematic approach to optimizing the diaphragm. It is often very difficult to see, especially in the left hemithorax, even in younger patients.
Take feedback from the screen. If gas in the stomach is obscuring the kidney in the left upper quadrant, move or sweep the probe posteriorly.
Always keep the spine on the screen to identify a spine sign. The presence of a spine sign will confirm that the dark echo cephalad to the diaphragm is pleural fluid and not mirror artefact or gas scatter from lung tissue.
Do not ask the patient to take a deep breath to bring the diaphragm closer to the probe. This will bring lung tissue more caudad and obscure the image from gas scatter. Sometimes asking the patient to breathe completely out and hold their breath will help improve how much of the diaphragm is seen.
Recognize that complex pleural effusions may have echogenic areas within the black pleural fluid. The most common example would be an empyema (i.e. purulent, infected pleural fluid) that will have scattered echogenic material floating in the black pleural fluid. This is called the plankton sign because of the similarity to plankton floating in the sea.
In patients with narrowly spaced ribs, the area of interest is often obscured near the end-points of sweeping, even with good probe rotation. If this is the case, the probe face can be moved slightly to allow the ultrasound beam to pass between the ribs more easily during the sweep. The probe face can be slid slightly posteriorly while the beam sweeps anteriorly (i.e. below a rib) or slid slightly anteriorly while the beam sweeps posteriorly (i.e. above a rib).
The use of the reverse Trendelenburg position can increase the sensitivity of the pleural effusion scan by maximizing the amount of fluid close to the diaphragm.
