Indian Journal of Radiology and Imaging Indian Journal of Radiology and Imaging

CHEST RADIOLOGY
Year
: 2011  |  Volume : 21  |  Issue : 3  |  Page : 182--190

A pictorial essay: Radiology of lines and tubes in the intensive care unit


Sanjay N Jain 
 Head of Radiology Department, Prince Aly Khan Hospital, Aga Hall, Nesbit Road, Mazagaon, Mumbai - 400 010, India

Correspondence Address:
Sanjay N Jain
Flat.No. 55, 5th Floor, Mamta DQBDQ CHSL, A. M. Marg, Prabhadevi, Mumbai-400 025, Maharashtra
India

Abstract

A variety of devices are used in the intensive care unit for long durations. Each one of them is a double-edged sword: intended to save life, but life-threatening if in the wrong place. Hence, it is important to periodically check that these devices are correctly placed so as to prevent complications. The portable chest radiograph is of tremendous value in this context.



How to cite this article:
Jain SN. A pictorial essay: Radiology of lines and tubes in the intensive care unit.Indian J Radiol Imaging 2011;21:182-190


How to cite this URL:
Jain SN. A pictorial essay: Radiology of lines and tubes in the intensive care unit. Indian J Radiol Imaging [serial online] 2011 [cited 2019 Sep 20 ];21:182-190
Available from: http://www.ijri.org/text.asp?2011/21/3/182/85365


Full Text

 Introduction



The chest radiograph (CXR) plays a crucial role in critically ill patients in intensive care units. It is the most common radiological investigation ordered due to its diagnostic value in cardiorespiratory disease. In addition, it is extremely useful for evaluating the position of various tubes, lines, and other devices and for detecting related complications.

The American College of Radiology (ACR) recommends a CXR immediately following placement of indwelling tubes, catheters and other devices to check the position and detect procedure related complications. [1] Bekemeyer and colleagues found that 27% of newly placed catheters or tubes were improperly positioned and that 6% resulted in a radiographically visible complication of the intervention. [2] Although many such abnormalities may not be immediately life-threatening, some require rapid correction to avoid clinical deterioration in patients with marginal cardiopulmonary reserve. All catheters have the potential risks of coiling, misplacement, knotting, and fracture. It is important to understand the function of a device as well as to recognize the complications associated with its use. We will now discuss the commonly used tubes and lines.

 Nasogastric Tube



The nasogastric (NG) tube is inserted for either feeding the patient or for aspiration of gastric contents, and for these purposes the tip should lie within the stomach. The NG tube has multiple side holes. There are terminal lead balls to facilitate identification of the tip. Ideally, the tip of NG tube should lie with its side holes in the gastric antrum. Pushing air into the NG tube while auscultating with a stethoscope over the stomach is the usual method by which correct positioning in the stomach is confirmed.

If the side holes are positioned within the esophagus there is increased risk of aspiration [Figure 1]. For this reason, the tip of the NG tube should be positioned at least 10-cm caudal to location of the gastroesophageal junction. Other naso/oro-enteric tubes are also encountered. The tip of a nasoduodenal feeding tube should be inserted at least 10-12 cm into the small bowel. {Figure 1}

Inadvertent insertion into the trachea and bronchus [Figure 2] can cause pneumonia, pulmonary contusion, or pulmonary laceration. Pharyngeal and esophageal perforations can occur but are rare. [3] {Figure 2}

 Endotracheal Tube



The endotracheal (ET) tube is inserted for ventilation of both the lungs and for prevention of aspiration. It has a terminal hole and a cuff. The satisfactory position of an ET tube in the neutral position of the neck is with the tip 5-7 cm above the carina. The location can vary approximately 2 cm in the caudal or cephalad directions with neck flexion and extension, respectively. [4] When the carina is not visible, the tip of the ET tube should be approximately at the level of the medial ends of the clavicle. It should lie midway between the larynx and carina so that injury to either structure or complications like inadvertent extubation or selective main-stem bronchus intubation are avoided. Selective intubation can cause collapse of the contralateral lung [Figure 3], hyperinflation of the ipsilateral lung, or pneumothorax. An immediate CXR after intubation is warranted because these complications are not uncommon and because the tube is quite commonly malpositioned. [5] Main stem intubation can be clinically occult in about 60% of patients and only revealed on the CXR. [6] One other thing that must also be checked for is an aspirated tooth. {Figure 3}

Inadvertent esophageal intubation [Figure 4] is a dreadful complication, which is mostly diagnosed clinically; it can be detected radiographically by the presence of an over-distended stomach. {Figure 4}

Tracheal stenosis can occur following long-term tube placement.

 Tracheostomy



The tip of the tracheostomy tube should be half way between the stoma and the carina, at the level of the D3 vertebra. Unlike the ET tube, its position is maintained with neck flexion and extension. The width of the tube (diameter) should be 2/3 rd of the tracheal width, and the cuff should not distend the tracheal wall. It should lie parallel to the trachea. The possible complications are surgical emphysema, pneumomediastinum, pneumothorax [Figure 5], hemorrhage, false tract, and tracheal stenosis. Hematoma causes widening of the superior mediastinum.{Figure 5}

 Drainage Tube



The pleural tube, more commonly known as the intercostal drainage tube (ICD), is inserted through the 4 th intercostal space in the anterior or mid-axillary line. It is then directed posteroinferiorly in cases of effusion and anterosuperiorly in cases of pneumothorax. The ICD tube has a terminal hole as well as side holes; the side holes can be identified on a CXR by the interruption in the radiopaque outline of the tube. No side holes should lie outside the chest/pleura and the tube should not float above the effusion like a 'lotus in the pond.' Chest tube malposition occurs in about 10% of placements, rendering the tube malfunctioning or nonfunctioning [Figure 6]. [1] Occasionally the tube tip may lie in an interlobar fissure or even within the lung parenchyma [Figure 7]. Both frontal and lateral CXRs are necessary to ensure proper positioning of the chest tube. Mediastinal drains are usually present following sternotomy and, except for their position, resemble pleural tubes in all respects. {Figure 6}{Figure 7}

 Central Venous Lines



Central venous lines (catheters) are useful for a variety of purposes, e.g., hemodynamic pressure monitoring; hemodialysis; and administration of medications, nutrition, and fluids. [7] They provide long-term venous access. Central venous lines are inserted through major veins such as the subclavian, internal jugular, or femoral veins into the superior vena cava. The tip of the line should be distal to the last venous valve, which is located at the junction of the internal jugular and the subclavian veins. On the CXR, the position of the valve corresponds to the inner aspect of the first rib [Figure 8]. Many central venous lines have two or three lumens, each with a different orifice. If the tip of the line is positioned in the superior vena cava, all orifices will be distal to the last valve. On the CXR, the first anterior intercostal space corresponds to the approximate site of the junction of the brachiocephalic veins to form the superior vena cava [Figure 8]. On the CXR, the cavoatrial junction corresponds to the lower border of bronchus intermedius [Figure 8]. [8] If the line tip reaches the right atrium, it can cause dysrhythmia or result in injection of undiluted toxic medications into the heart.{Figure 8}

In about 30% of cases the initial radiographs show a malpositioned central venous line. [9] Complications vary with the type of line and the site of insertion. [10] Pneumothorax occurs in up to 6% of procedures and is more common with the subclavian approach [Figure 9]. [5] If initial placement fails, a CXR before attempting the procedure on the other side helps avoid bilateral pneumothoraces. {Figure 9}

If the central venous line tip abuts the venous wall there is a risk of vessel perforation, with resultant infusion of fluid into the mediastinum or pleural or pericardial space. On the CXR, this complication will appear as mediastinal widening [Figure 10], enlargement of the cardiac silhouette, or a new pleural effusion [Figure 11]. {Figure 10}{Figure 11}

Other complications are abnormal course, cardiac perforation, and arrhythmias. Abnormal course of a central venous line or malpositioning occurs when it enters a tributary such as the azygos vein, subclavian vein, internal mammary vein, or an anomalous vein such as a persistent left-sided superior vena cava; the line may even enter the carotid vessels [Figure 12]. [11] {Figure 12}

 Pulmonary Artery (Swan-Ganz) Catheter



The Swan-Ganz catheter is a flow-directed balloon-tipped pulmonary artery catheter. The balloon is inflated to measure the capillary wedge pressure. This catheter is widely used for monitoring circulatory hemodynamics in the management of a variety of critical illnesses. To measure pulmonary artery pressure and capillary wedge pressure, the tip of catheter needs to be in the right or left pulmonary artery. To avoid complications, the tip of the Swan-Ganz catheter must not be more than 1 cm lateral to the mediastinal margin. The rule of thumb is that the catheter should not extend beyond the pulmonary hilum on the CXR; else, it should be retracted. [12] The complication rate of pulmonary infarction is reduced when the balloon is inflated only during pressure measurement and insertion. Potential complications are intracardiac knotting, pulmonary infarction [Figure 13], pulmonary artery perforation, arrhythmias, cardiac perforation, and placement in the inferior vena cava [Figure 14]. {Figure 13}{Figure 14}

 Intra-aortic Balloon Pump



Intra-aortic balloon pump (IABP) is a long-balloon temporary circulatory assist device that works on the principle of cardiac counter-pulsation. The IABP is used to support the circulation. The balloon, approximately 25-cm long, is mounted on a catheter. The catheter tip is visible as a 3 x 4-mm rectangular metallic density while the rest of the catheter is radiolucent [Figure 15]. The catheter is inserted through the femoral artery. The balloon is inflated with gas during diastole and deflates during systole, resulting in increase in coronary blood flow and reduction in left ventricular afterload (and hence, reduction in myocardial oxygen consumption). [13] The various indications are acute myocardial infarction (MI) with cardiogenic shock, post-coronary artery bypass graft (high-risk cases with low ejection fraction of <20%), acute mitral insufficiency, and cardiac transplantation. It is contraindicated in aortic regurgitation, aortic dissection, and in the presence of a prosthetic graft in the thoracic aorta (within 12 months of surgery). To avoid occlusion of the left subclavian artery and visceral and renal arteries, its tip should be slightly cephalad to the adjacent carina (2 nd -3 rd intercostal space). The balloon should not occlude more than 85-90% of the aortic diameter. Balloon rupture with air embolization and septicemia are rare potential complications.{Figure 15}

 Pacemaker



Pacemakers are used in cases of severe sinus node dysfunction, complete heart block, and various arrhythmias. They have two main elements: a pulse generator and a lead wire with electrodes. The single-lead pacemaker is the most basic type and is positioned with its tip in the right ventricular apex [Figure 16]A. An atrioventricular two-lead sequential pacemaker has one electrode in the right atrium and the other at the right ventricular apex [Figure 16]B. Sometimes a third lead is placed in the coronary sinus to pace the left ventricle [Figure 17]. It is not feasible to insert an electrode in the left side of the heart due to the high pressures in these chambers. Temporary epicardial wires are sometimes inserted during cardiac surgery; the tips of these wires resemble a corkscrew. They can be removed easily.{Figure 16}{Figure 17}

A lateral CXR is usually required to confirm the position of the electrode in the right atrial appendage. The tip points anteriorly when correctly positioned. The tip may have a slight bend as it abuts the wall but there should no sharp bends. The potential complications are malposition, intracardiac knotting [Figure 18], fracture, perforation [Figure 19], cardiac tamponade, arrhythmias, infection, and hemorrhage. Twiddler's syndrome is a rare disorder in which twisting of the lead occurs either due to the patient's manipulation or spontaneously [Figure 20].{Figure 18}{Figure 19}{Figure 20}

 Automated Implantable Cardioverter Debrillator



Automated implantable cardioverter debrillator (AICD) is used in cases of recurrent refractory ventricular tachycardia. It has two electrodes (one electrode in the right atrium and the other in the right ventricle). The lead is wider compared to the pacemaker lead and has a 'coiled-spring' appearance [Figure 21]. Complications are similar to those with transvenous pacemakers and the incidence of radiographical abnormalities may approach 20%.{Figure 21}

 Pediatric Lines



Some catheters are only used in the pediatric population, for example, the umbilical artery and venous catheters. They are used for vascular access for exchange transfusion; hyperalimentation; and measurement of blood gases, pressures, electrolytes, etc. The umbilical vein and arteries remain patent for up to 4-5 days after birth. The umbilical venous catheter courses anteriorly and cephalad in the midline, with posterior angulation in the liver [Figure 22]. The umbilical artery catheter initially dips into the pelvis to enter the iliac artery before coursing superiorly in the aorta [Figure 22]. [14] {Figure 22}

The umbilical venous catheter should reach the base of the right atrium or the cephalad portion of the inferior vena cava [Figure 22]. This is sometimes difficult to ascertain. The rule of thumb is that the tip should be approximately at the level of D8-D9 vertebrae. It lies on the right side on the anteroposterior radiograph. On the lateral CXR, it lies anteriorly [Figure 22]. The initial radiograph may show air in the portal system introduced during procedure. There should be no coiling, bend, or kink in the catheter. Insertion into the hepatic vein, peripheral portal vein [Figure 23], left atrium [Figure 24], right ventricle, or even into the pulmonary arteries can occur. Cardiac perforation, cardiac arrhythmias, valvular injury, and portal vein or pulmonary artery thrombosis are some of the complications. [15],[16]{Figure 23}{Figure 24}

The umbilical artery catheter should be at the level of the D6-D10 vertebrae (high position) or at the level of the L3-4 vertebrae (low position) to ensure that its tip is away from the origins of vessels supplying vital organs (the carotids in the high position and the renal vessels in the low position). The high position is usually preferred. Thrombosis and ischemia are well-known complications. In contrast to the umbilical venous catheter, the umbilical artery catheter dips initially before it takes a path parallel to the spine on the left side [Figure 22]. On a lateral CXR, it lies posteriorly.

 Conclusion



The portable CXR is invaluable for monitoring the various indwelling devices used in critically ill patients. A systematic approach and knowledge of the radiographic features of the common indwelling tubes and lines is of the utmost importance.

 Acknowledgement



The author expresses his gratitude to Dr. Vinod Attarde and Dr. Ravi Varma for their valuable contribution.

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