Tubes & LinesRadiographic Evaluation of the Placement of Monitoring and Support DevicesTula TopFebruary 20, 2004

Central Venous Catheters

Central Venous CathetersPurposeCentral venous catheters, also known as central venous pressure (CVP) lines, are used to monitor central venous pressure in the ICU and also allow for intravenous fluid or medication administration.

Central Venous CathetersAccess and PlacementCVP lines are typically inserted through the internal jugular, subclavian, or femoral veins, and offer more consistent venous blood flow than more peripherally inserted catheters, which may be subject to compression via vasoconstriction during times of cardiovascular collapse. The CVP line should ideally be positioned central to the venous valves at the origin of the superior vena cava. The SVC is formed by the junction of the right and left brachiocephalic veins and lies to the right of midline at the level of the first intercostal space.

The following radiograph demonstrates a CVP line in the proper position.

Central Venous Catheters

Central Venous CathetersWhats the finding in the following chest radiograph?

Click for a hint.

The CVP line is in the left Subclavian Artery.Click for another hint.

The CVP line is in the left Subclavian Artery.We expect the line to end up hereClick for another hint.

We expect the line to end up hereThe CVP line is in the left Subclavian Artery.Then, where is the tip located?Click for the answer.

Central Venous CathetersAnswer: The tip is in Descending Thoracic Aorta. When the line extends above the clavicle, it is very likely that it lies in the subclavian artery. The subclavian vein normally lies behind the clavicle.

Differential Location (if in vein):A left-sided SVC is a normal anatomic variant in 0.3% of individuals, of whom some two-thirds will also have a right-sided SVC. A large proportion of these individuals also will have the left BCV connecting to both the right and left SVCs. When the SVC is duplicated, the vessels typically are relatively smaller in caliber than those in patients with single SVCs. The left SVC drains through the oblique vein of the left atrium, the great cardiac vein, and the coronary sinus into the right atrium.

Biffi M., et al. Left superior vena cava persistence in patients undergoing pacemaker or cardioverter-defibrillator implantation: a 10-year experience. Chest. 120(1):139-44, 2001 Jul.

Which Line Did you Put in?The Right or Left Subclavian?

Which Line Did you Put in?The Right or Left Subclavian?Right Subclavian ArteryLeft Subclavian Vein

Central Venous CathetersWhats the finding in the following chest radiograph?

Click for a hint.

Is the CVP line in the right place?Click for another hint.

Is the CVP line in the right place?Yes, it is. But whatand whereis this lucency?Click for the answer.

Central Venous CathetersComplicationsAir embolization is a potentially fatal complication of venipuncture and line placement and may be detected on CXR or CT with concomitant intravenous contrast injection.

Central Venous CathetersComplicationsCatheters placed in the left brachiocephalic vein should demonstrate an anterior curve on the lateral chest radiograph as the left BCV courses anteriorly to join the right BCV. A posterior projection of the catheter tip suggests placement into the azygos vein, which joins the SCV posteriorly prior to entering the pericardium. Such malpositioning may be missed if evaluated solely by a PA radiograph. Suspect placement of the catheter tip merits orthogonal views to confirm its location.

Central Venous CathetersComplicationsThe vasculature in close proximity to the heart offers a number of aberrant routes for an inserted CVP line to follow. Among the most common are the:Internal jugular veinRight atrium (with risk of perforation or dysrhythmias if placed near the tricuspid valve)Right ventricleOpposite subclavian veinCorresponding arteryNumerous extrathoracic locations (with potential of ectopically infusing toxic substances in the vicinity of the liver or heart instead of into the central venous system where rapid dilution can occur; look for widening and opacification of the mediastinum or pleural space due to rapid accumulation of fluid.)Venous perforation may also occur if a catheter tip abutting the lateral wall of the SVC places excessive focal pressure on the wall.

Central Venous CathetersComplicationsEvery chest radiograph that features a CVP catheter should be evaluated carefully for pneumothorax, which occurs with 6% of line placements and can manifest several days after the procedure. Moreover, there is an increased potential for bilateral PTX given that a PTX on one side may have gone undetected following an initial failed attempt at line insertion before success was finally achieved on the other side.Catheter embolization can occur as a result of laceration of the catheter by the insertion needle, catheter fracture at a point of stress, or detachment of the catheter from its hub. The freed apparatus may lodge in the SVC, inferior vena cava, right heart, or pulmonary artery, causing thrombosis, infection, or perforation.

Central Venous CathetersComplicationsThe catheter tip may serve as a nidus for clot formation, impairing its ability to measure central venous pressure accurately or to deliver fluids to the venous system.Extension of the clot may result in venous thrombus or pulmonary embolus.The pinch-off syndrome refers to impingement of the catheter between the clavicle and the first rib. This can result in fracture of the catheter or fragmentation.

Central Venous CathetersSummary of complications

Swan-Ganz Catheters

Swan-Ganz CathetersPurposeSwan-Ganz (pulmonary artery flotation) catheters are placed to aid in the differentiation of cardiogenic from noncardiogenic pulmonary edema by allowing the clinician to monitor pulmonary capillary wedge pressure, reflecting left atrial pressure and left end-diastolic volume, via a central channel. Another channel allows assessment of central venous pressure and cardiac output. A third channel connects to an inflatable balloon at the catheter tip, which when inflated causes the tip to float distally through the arterial system and when deflated causes it to resume a more central position.

Swan-Ganz CathetersA CaveatDespite research indicating that radiographic findings allow a more accurate means of distinguishing between cardiogenic versus noncardiogenic edema, SG catheters are still in widespread use throughout all medical centers.

Milne E.N., et al. The radiologic distinction of cardiogenic and noncardiogenic edema. American Journal of Roentgenology. 144(5):879-94, 1985 May.

Swan-Ganz CathetersAccess and PlacementAccess is usually gained via the subclavian vein, but jugular and femoral vein approaches are also employed via use of a sheath called a cordis that facilitates advancement and withdrawal of the catheter and can provide short-term venous access once the SG is removed. The catheter tip is ideally positioned within the left pulmonary artery or the proximal interlobar artery.

The following radiograph demonstrates a SG catheter in the proper position.

Click to locate the NGT.

Click to locate the ETT.

Click to locate the SGC.

Click to proceed.

Swan-Ganz CathetersWhats the diagnosis in the following chest radiograph?

Click for a hint.

Is the SGT in the right place?Click for another hint.

Is the SGT in the right place?Click for the answer.

Swan-Ganz CathetersComplications:Pulmonary infarction can also arise as a result of a persistently inflated balloon obstructing a major pulmonary artery. The inflated balloon appears as a 1-cm rounded radiolucency at the catheter tip. It should be inflated only when pressure measurements are being taken, and never while chest radiography is being performed. Dr. Gosselin will hunt you down if you do this!

Swan-Ganz CathetersWhats the finding in the following chest radiograph?

Click for a hint.

Click for the answer.

Swan-Ganz CathetersComplicationsAberrant insertion of the SG catheter can also result in pulmonary artery rupture, pulmonary artery pseudoaneurysm, pulmonary artery to bronchial tree fistula, balloon rupture, and intracardiac knotting of the catheter. Other complications of SG catheters are similar to those that can occur with CVP lines. Also, redundancy or coiling of the SG catheter in the right heart can irritate the conduction bundle and induce dysrhythmias.

Swan-Ganz CathetersComplicationsThe risk of pulmonary infarction increases the more distally the catheter tip is advanced, as the vessel diameters approach that diameter of the tip. Likewise, clot formation about the tip can lead to occlusion of the vessel in which it resides. Infarctions can be recognized on CXR by the appearance of patchy airspace opacification that is often wedge-shaped and subpleural in location.

Swan-Ganz CathetersSummary of ComplicationsComplications associated with central venous pressure catheter placementPulmonary infarctionDistal placement of catheter tipFailure to deflate balloonArrhythmiaCatheter tip in right atrium or right ventricleExcessive coiling or redundancy of catheter tubing in right heartPulmonary artery pseudoaneurysmPulmonary artery rupturePulmonary artery to bronchial tree fistulaIntracardiac knotting of catheterBalloon rupture

Intra-Aortic Balloon Pumps

Intra-Aortic Balloon PumpsPurposeThe intra-aortic balloon pump consists of a long inflatable balloon 26-28cm in length surrounding the distal end of a centrally placed catheter. It is used in the setting of cardiogenic shock to enhance cardiac function.

Intra-Aortic Balloon PumpsAccess and PlacementThe balloon pump is introduced via the femoral artery and advanced retrograde into the thoracic aorta. The balloon is ideally situated with the tip located just distal to the left subclavian artery at the level of the aortic arch. Such placement ensures maximal augmentation of diastolic pressures in the proximal aorta. Inflation of the balloon during diastole increases diastolic pressure, enhancing perfusion of the coronary arteries and oxygen delivery to the myocardium. Deflation of the balloon during systole creates a vacuum within the vessel lumen, decreasing ventricular afterload and enhancing forward blood flow.

The following radiograph demonstrates an IABP in the proper position.

Click to locate the SGC.

Click to locate the IABP tip.

Click to locate the IABP proper.

Click to proceed.

Intra-Aortic Balloon PumpsComplicationsEven with ideal positioning, the long lumen of the IABP traverses the ostia of the celiac trunk, superior mesenteric artery, inferior mesenteric artery, and renal arteries and can lead to occlusion of these vessels (mesenteric ischemia, renal failure).Too proximal a placement of the IABP can lead to obstruction of the left subclavian artery or cerebral embolus.Too distal a placement of the IABP results in suboptimal counterpulsation during diastole.Aortic dissection and death can rarely occur with advancement of the catheter during IABP placement.Potential complications also include traumatic platelet and red blood cell destruction, peripheral emboli, balloon rupture with resultant gas embolus, and vascular insufficiency of the catheterized limb.

Intra-Aortic Balloon PumpsSummary of ComplicationsBalloon advanced too farObstruction of left subclavian arteryCerebral embolusBalloon not advanced far enoughInadequate counterpulsation during diastoleAortic dissectionReduction of plateletsRed blood cell destructionEmboliBalloon rupture with gas embolusRenal failure (balloon occlusion of renal artery)Vascular insufficiency of catheterized limb

Endotracheal Tubes

Endotracheal TubesPurposeIntubation of the airway by oral or nasal ETT (or alternatively by cricothyroidotomy or tracheostomy) and mechanical ventilation may be required in situations involving airway obstruction, disorders of gas exchange, or failure of the airways protective mechanisms. ETTs help prevent large aspirations, but small aspirations still occur continuously.

Endotracheal TubesAccess and PlacementMost ETTs are radiopaque or feature an opaque tip to facilitate evaluation of placement by chest radiography. The tip should be located at least 3 to 4 cm above the carina (roughly at the level of T6 on portable CXR)ideally at the level of T4and at least 3 to 4 cm below the vocal cords (roughly C6) in adults. The ETT moves with the chin: With extension of the neck from the neutral position, the tip recedes cephalad up to 2 cm; with flexion, the tip advances caudad up to 2 cm. It is thus imperative to determine the patients head position before making any recommendations to reposition the ETT.

The following radiograph demonstrates an ETT in the proper position.

Click to locate the ETT.

Click to locate a helpful landmark.

Click to locate more landmarks.

Click to proceed.

Endotracheal TubesWhats the finding in the following chest radiograph?

Click for a hint.

Click for the answer.

Endotracheal TubesComplicationsThe cuff (balloon) of the ETT should be inflated to fill the lateral tracheal walls (i.e., equal to or slightly greater than the diameter of the trachea to provide a secure seal), but it should not be bulging, as in the preceding radiograph. Also, in the preceding radiograph the ETT has not been advanced far enough into the trachea before the cuff, residing in the hypopharynx, was inflated. Placement of the ETT too near the vocal cords may lead to vocal cord injury when the cuff is inflated.

Endotracheal TubesWhats the diagnosis in the following chest radiograph?

Click for a hint.

What does this lucent tract represent?Click for another hint.

What does this lucent tract represent?Whats happened to the left lung, and why?Click for the answer.

Endotracheal TubesComplicationAdvancement of the ETT into the right mainstem bronchus is one of the most common errors encountered during intubation. The left lung typically collapses when this occurs. The left mainstem bronchus is clearly visible, as indicated by the first hint.

Endotracheal TubesComplicationsInsertion of the ETT into the esophagus is a life-threatening complication. On CXR, the ETT will be situated just lateral to the trachea. As with pharyngeal placement, the stomach becomes markedly distended, though aspiration does not occur due to occlusion of the esophagus by the ETT cuff.Pharyngeal placement of the ETT results in disrupted mechanical ventilation and may distend the stomach with air, with aspiration of gastric contents.Intubation can result in tracheal laceration with an overinflated cuff herniating through the tear on CXR. A concomitant pneumothorax or pneumomediastinum may also be observed.Overinflation of the cuff may occur with inadvertent hyperinflation, intraesophageal placement, chronic intubation, or tracheomegaly.ETT placement is associated with an increased incidence of sinusitis due to mucosal edema and obstruction of sinus drainage.

Tracheostomy Tubes

Tracheostomy TubesPurposeTracheostomy tubes are usually placed one to three weeks following ETT placement in patients requiring ongoing mechanical ventilation or tracheal suctioning.

Tracheostomy TubesPlacement and Positioning:A stoma is created at the level of the third tracheal cartilage, though which the tracheostomy tube is inserted. Like ETTs, the tip should be situated several centimeters above the carina; unlike ETTs, however, the position of the tip does not vary considerably with head flexion or extension, and the cuff should not extend to the tracheal wall.

The following radiograph demonstrates an NGT in the proper position.

Note that there is slight rotation in this view. Click to proceed.

Tracheostomy TubesNoteIt is not uncommon to observe slight subcutaneous emphysema in the neck and upper mediastinum following surgical placement of the tracheostomy tube. It is usually mild and self-limited, and patients and their families should be reassured accordingly.

http://www.perspectivesinnursing.org/v1n1/Dixon.html

Tracheostomy TubesWhats the finding in the following chest radiograph?

Click for a hint.

Whats the expected orientation of a properly placed ETT?Click for the answer.

Tracheostomy TubesComplicationsMassive, clinically significant subcutaneous emphysema can occur as a result of paratracheal insertion or tracheal perforation (the latter depicted in the preceding radiograph). Pneumothorax can occur if the apical pleural space is breached during surgery but can also arise in the setting of tracheal perforation. Subsequent radiographs of the preceding patient should be meticulously checked for all of the above sequelae following surgical revision of the tracheostomy tube placement.

Tracheostomy TubesComplicationsSome degree of mucosal injury occurs in every patient undergoing placement of a tracheostomy tube due to mucosal irritation and bacterial colonization. A few cases may progress to ulceration and, potentially, cartilage necrosis.Mucosal edema, erythema, and superficial ulcerations following extubation usually heal of their own accord. Deep ulcerations, however, can lead to permanent laryngeal scarring, tracheal stenosis, and tracheomalacia. These may not fully manifest for several weeks to months following extubation, and all subsequent CXRs should be evaluated for any laryngeal or tracheal narrowing.

Tracheostomy TubesComplicationsBarotrauma and air leak can occur in up to 50% of patients, and those with adult respiratory distress syndrome are at increased risk. Air escapes from the ruptured alveoli and dissects medially along the bronchovascular connective tissue towards the mediastinum. If the pressure increases, air can track cephalad into the neck or follow the esophagus caudad to the retroperitoneum, continuing along the anterior and posterior perirenal space and properitoneal fat. In men, if this does not sufficiently decompress the mediastinum, air can dissect along the anterior abdominal and chest wall and into the scrotum. Ultimately, air can rupture into the peritoneum and the into the pleural space by way of the mediastinal parietal pleura.

Tracheostomy TubesSummary of ComplicationsMalpositionRight mainstem ETT intubation leads to hypoventilation or collapse of left lungDislodgment from trachea interrupts mechanical ventilationPlacement just beyond vocal cords leads to vocal cord injury when cuff is inflatedPlacement within esophaguslook for:Gastric dilatationOverinflated cuff lung hypoventilationLateral placement of tubeTracheal or laryngeal lacerationlook for:PneumothoraxPneumomediastinumTracheostenosisTracheomalacia

Chest TubesPurposeChest tubes may be required to evacuate the pleural space of air, blood, pus, or other pleural fluid.

Chest TubesPlacement and PositioningThe side hole of the chest tube is marked by an interruption in the radiopaque strip that runs the length of the tube. This hole should be located medial to the inner margin of the ribs.

The following radiograph demonstrates a chest tube in the proper position.

Click to locate the chest tube.

Click to proceed.

Chest TubesWhats the finding in the following chest radiograph?

Click for a hint.

Note the smooth curvature of the chest tube.Click for the answer.

Chest TubesComplicationsThe chest tube is likely located within a fissure when it reproduces the anatomy of the major or minor fissure as in the preceding radiograph (tube resides within the right major fissure). Frontal CXR ideally should demonstrate a vertically oriented radiopacity; a more horizontal course with gentle curvature of the chest tube (red arrow) suggests location within a fissure. Such location may result in occlusion of the tube by the surrounding lung parenchyma, rendering suctioning ineffective.

Chest TubesWhats the finding in the following chest radiograph?

Click for a hint.

What does this lucency represent?Click for the answer.

Chest TubesComplicationOther errors of placement include placement of the chest tube within the subcutaneous tissues, advancement into the mediastinum, within the lung parenchyma, or through the liver, spleen, or diaphragm (as in the preceding radiographnote the area of lucency representing colonic air), resulting in a bronchopleural fistula, hemorrhage, or infection. Following removal of the chest tube there may be a residual pleural or parenchymal line on CXR representing the tubes prior course. This should not be mistaken for the visceral pleural edge of a pneumothorax. Rapid lung reexpansion may result in pulmonary edema when the amount of pleural fluid removed is large (>1.5L).

Nasograstric Tubes

Nasogastric TubesPurposeNG tubes are used for suctioning gastric contents (as in treatment of small-bowel obstruction).

Nasograstric TubesAccess and PositioningThe tip of the NG tube should reside within the stomach, with the side port lying beyond the gastroesophageal junction. The NG tube appears as a 1-cm diameter tubing with a single thick radiopaque stripe and a break in the stripe 6 cm from the tip representing the side port.

The following radiograph demonstrates an NGT in the proper position.

Click to locate the ETT.

Click to locate the SGC.

Click to locate the NGT.

Click to proceed.

Nasogastric TubesComplicationsMost relate to malpositioning, such as incomplete insertion and/or tube coiling within the esophagus, which predisposes the patient to aspiration.

Dobhoff Feeding Tubes

Dobhoff Feeding TubesPurposeInfusion of enteral nutritional support or medications.

Dobhoff Feeding TubesAccess and PositioningDobhoff tubes are inserted orally or nasally and are ideally situated within the third part of the duodenum, almost to the ligament of Treitz, although placement within the proximal duodenum is adequate. It appears as a thin 3-mm tube with a weighted radiopaque distal tip. The side port lies just proximal to the weighted tip.

The following radiograph demonstrates a Dobhoff in the proper position.

Click to locate a helpful landmark.

Click to locate the ETT.

Click to locate the Dobhoff tube.

Click to proceed.

Dobhoff Feeding TubesComplicationsDobhoff tubes may inadvertently be introduced into the lungs (with tube feeds leading to overwhelming pneumonia), pleural space, or even through the diaphragm, or the tip may be placed in the hypopharynx or esophagus, which may perforate during insertion. Esophageal perforation may manifest as pleural effusion, pneumomediastinum, extraesophageal location of the tube, mediastinal widening, and mediastinal air-fluid levels that can be detected radiographically.

References

Amorosa, J.K. Essentials of Radiology. CD-ROM 1999.

Collins, J., and Stern, E.J. Chest Radiology: The Essentials. Lippincott Williams & Wilkins: Philadelphia 1999.

Dixon, L. Tracheostomy: Postoperative Recovery. Perspectives: Recovery Strategies from the OR to Home. LINK

Milne E.N., et al. The radiologic distinction of cardiogenic and noncardiogenic edema. American Journal of Roentgenology. 144(5):879-94, 1985 May.

Mullan, B. Positions of Tubes and Lines on Chest Films. Virtual Hospital. LINK

Biffi M., et al. Left superior vena cava persistence in patients undergoing pacemaker or cardioverter-defibrillator implantation: a 10-year experience. Chest. 120(1):139-44, 2001 Jul.