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On-Call Radiology

Pneumothorax (PTX)

  • Particularly important to consider in ICU patients who are receiving positive end-expiratory pressure(PEEP). 5-15% of those on mechanical ventilation can develop extrapulmonary air (PTX, pneumomediastinum, subpleural air).
  • Tips for identifying a PTX:
    • A small PTX in an upright patient collects at the apex. The lung apex retracts toward the hilum and thesharp white line of the visceral pleura will be visible, separated from the chest wall by the radiolucentpleural space — which is devoid of lung markings.
    • If a pneumothorax is suspected but not initially apparent, an expiratory film will make it easier to seebecause lung volume will be at its lowest.
    • A lateral decubitus film with the affected side up may reveal air along the lateral chest wall.
    • A deep sulcus sign [deep lateral costophrenic angle on the involved side] or a wavy heart border sign inpatients that with pneumothorax who are supine may be seen.
    • Depression of the hemidiaphragm is the most reliable sign for a tension PTX
    • Any suspicion of PTX warrants a non-contrast CT scan of chest since CXR correlates poorly with actualsize.

Endotracheal tube (ETT) placement

  • 12-15% of patients will have malpositioning of the ETT on initial placement.
  • The tip of the ETT should be positioned 4-6 cm above the carina with the patient’s neck in a neutralposition.
  • Flexion of the neck = movement of ETT inferiorly (towards carina) on CXR and vice versa.

Central Venous Catheter (CVC) Position and Placement

  • A CVC catheter tip should ideally be located at the cavoatrial junction.
  • A PICC line catheter tip should be located the inferior aspect of the SVC.
  • CXR landmarks and findings related to CVC placement
    • The arch of the azygous vein is a landmark for the SVC.
    • The right mainstem bronchus is a landmark for the junction of the SVC and the right atrium. Therefore, inferior to the right mainstem bronchus corresponds to a position within the right atrium.
    • The development of a new pleural effusion after line placement should be considered pleural hematoma orextravasation of fluid from the line until proven otherwise.

Nasogastric (NG) and feeding tubes (FT)

  • Common indications for NG tubes include decompression of the stomach (e.g. for ileus or bowel obstruction), medication administration, or enteral nutrition. Obstruction of the esophagus may occur if the NG tube is not inserted far enough into the stomach; at least 10 cm of the tip should be within the stomach.
  • NG tubes are contraindicated in esophageal strictures (risk of perforation) or basilar skull fracture or facial fracture (risk of intracranial misplacement), but safe in patients with varices.
  • The two most common types of NG tubes you will encounter are Salem Sump (suction tube; stiffer, has two lumens for aspiration and irrigation/medication delivery/feeding, more commonly used for decompression but can be irritating), and dobhoff (flexible feeding tube; more flexible, narrower, goes into duodenum, commonly used for feeding but cannot be used for decompression because they collapse with suction)
  • Ideal placement of feeding tubes depends partly on the clinical situation. In general, a feeding tube placed in the stomach poses no greater aspiration risk than a feeding tube placed beyond the pylorus. For patients with high reflux risk, placement beyond the pylorus is often recommended, though supportive data is lacking. IV metoclopramide may aid in the passage of feeding tubes beyond the pylorus.
  • Xrays are often not necessary for NG tubes (e.g. Salem Sump) used for decompression. Instead, clinical confirmation can be obtained by visualizing return of gastric contents or warm water that is flushed in with a syringe.
  • Xrays are necessary to confirm placement of feeding tubes (enteral tubes). The unintentional placement of a feeding tube into the airway is a potentially life-threatening complication that is not always obvious.
  • Placement is sometimes difficult to determine with a portable radiograph of a poorly positioned patient.
  • Merely assuring that the tip of the feeding tube is over the gastric bubble is not adequate confirmation – one must follow the entire course of the tube to ensure that it does not follow the course of a bronchus. If there is any question, do not clear the feeding tube for use.
  • X-ray confirmation is required before using for medication, fluids or feedings
  • Placement must be confirmed by a radiologist.
shared/general/radiology.txt · Last modified: 2019/12/14 01:55 by 127.0.0.1