Selecting and Troubleshooting Suction Devices

To remove retained secretions, blood or other semi-liquid fluids from the large airways, you suction the patient. To suction a patient, you apply vacuum (negative) pressure to the airway through a suction device. This sheet focuses on the actual airway devices used to remove secretions. For guidance on assembly and troubleshooting of the systems that generate the vacuum pressure (suction pumps, vacuum regulators), click here.

Selecting the Proper Suction Device

To select the proper suction equipment, you need to answer four basic questions:

The following table outlines the key considerations raised by these questions and provides recommendations on proper suction device selection:




Where to Suction

Oral Cavity/Nasal Passages (newborn)

Choose bulb suction



Choose Yankauer tip



Select standard suction catheter


Bronchus (R or L)

Coude (curved) tip catheter


Nasal Route (frequent)

Consider nasopharyngeal airway

Patient Size/Age

Catheter Diameter

Varies - apply formula


Catheter Length

Limit depth with infants

Patient Condition

Meconium Aspiration

Use meconium aspirator connected to ET tube



Consider closed suction system


Leakage Aspiration

Consider continuous aspiration system


Airway Clearance

Use standard systems


Sputum Collection

Use collection trap

Where to Suction

Oral Cavity/Nasal Passages of Newborn. fter warming, drying and positioning a newborn infant, you normally clear the upper airway using a bulb suction device (if meconium is present, see below). The mouth is suctioned first, then the nose. This helps prevent aspiration of secretions that can occur if the infant gasps due to mechanical stimulation of the nasal passageway. You should be careful not to suction too deeply, as this can cause a vagal response and severe bradycardia and/or apnea.

Oropharynx. If you need to clear the oropharynx of secretions, blood or other semi-liquid fluids, select a Yankauer suction tip (figure to left). Most of these units are disposable and come with a 6 foot length of connecting tubing. To assemble and check a Yankauer suction tip, aseptically remove the unit and its tubing from its package, attach the connecting tubing to the suction source, and set and confirm the desired vacuum pressure by obstructing the tip. Some Yankauer tips come with a thumb port that allows control of when suction is applied.

Trachea. If you simply need to clear secretions from the trachea, select a standard suction kit with the proper size catheter for the patient (see below). A typically disposable suction kit (figure to right) contains the suction catheter, 1 or 2 gloves and either a sterile basin or a small sterile bottle of water. Most centers use suction catheters that include both a distal tip and a side eye-hole. This design tends to minimize the damage that can occur when a single hole catheter adheres to the tracheal mucosa.

Mainstem Bronchi. If you need to reach either the left or right mainstem bronchus for suctioning, select a Coude (curved) tip catheter (figure to right). This type catheter helps overcome the angulations at the carina that make blind entry into the bronchi (especially the left) difficult. A marker on the Coude catheter indicates the direction of curvature. To gain access to a mainstem bronchus, you orient the catheter curve toward the desired bronchus (left or right) while having the patient turn their head to the opposite (contralateral) side.

Nasal Route. If the chosen route is nasopharyngeal and the patient will need frequent suctioning (many times per day), you should consider inserting and leaving a nasopharyngeal airway in place. This can help minimize trauma to the nasal mucosa due to frequent catheter passage. An alternative is to ease passage by lubricating the catheter with a sterile water soluble lubricating jelly

Patient Size/Age

Catheter Diameter. For tracheal suctioning, you select a catheter according to the age of the patient and the size of the artificial airway. The table below provides recommended catheter sizes (French units) according to the internal diameter of the tracheal airway:


Tube Size
(ID mm)

Catheter Size







6 months



18 months



3 years



5 years



6 years



8 years



12 years



16 yrs/small adult female



Adult females (average)



Adult males



In general, the external diameter of the suction catheter you select should be no more than ½ the internal diameter of the artificial airway. Rather than memorize the above table, you can apply a simple formula to estimate the correct catheter size. Simply multiply the internal diameter (ID) of the tube (in mm) times 3/2. Since this simple formula slightly underestimates size, you can safely use the next larger Fr size (with the exception of the 5 Fr, catheters come in even sizes). For example, to suction a patient with an 8.0 mm tube:

(3 x 8) ÷ 2 = 12
Next larger size = 14 Fr catheter

Catheter Length. Catheter length is most important in infants. In most centers, infant suctioning protocols call for catheter insertion only to the tip of the ET tube. As shown in the figure below, you determine proper catheter insertion distance by noting the cm mark on the exterior of the endotracheal tube that corresponds to the level of the adapter. You then add the adapter length (usually about 4 cm) to the cm mark on the ET tube, This total distance (from the tip of the ET tube to the opening of the adapter) is the proper depth for catheter insertion. Once you determine the insertion depth, make sure you record it in the medical record and also visibly at the infant’s bedside (to assure consistency when suctioning).

Patient Condition

There are three specific patient conditions that may require special suction equipment: (1) meconium aspiration in newborn infants; (2) patients with acute lung injury (requiring mechanical ventilation) who need suctioning and (3) patients with artificial tracheal airways who have a problem with leakage-type aspiration.

Meconium Aspiration in Newborn Infants. If tracheal suctioning of an infant with suspected meconium aspiration is indicated, the baby is immediately intubated with an appropriate size ET tube. You then apply suction continuously to the ET tube as it is withdrawn using a meconium aspirator attached to a wall suction regulator set to -100 mm Hg.

Patients with Acute Lung Injury Who Need Suctioning. Suctioning lowers alveolar PO2s and FRC. In patients with acute lung injuries receiving ventilatory support (including IRDS and ARDS), these changes can worsen arterial hypoxemia. To minimize this problem, you should select a ‘closed’ suction catheter system (figure below).

From Sills JR. Respiratory Care Certification Guide. 2 ed. St. Louis: Mosby; 1994.

You incorporate a closed suction catheter directly into the ventilator circuit. With this type catheter, you can suction without disconnecting the patient from the ventilator. Since PEEP and a high FIO2 are maintained (the FIO2 is still increased prior to suctioning with these systems), these catheters can help minimize arterial hypoxemia during suctioning. Below are the basic steps to use when suctioning a patient with a closed suction catheter system (does NOT include patient preparation and follow-up):

1. Place cap on either side of T-piece (opposite ventilator circuit connection) and make sure irrigation port is closed

2. Attach suction control valve to the wall suction

3. Prior to patient attachment, turn on wall suction and set at desired level while depressing control valve

4. Attach T-piece to ventilator circuit (if desired, place flex tube between circuit and T-piece)

5. Attach T-piece to endo/trach tube connector (if desired, use swivel connector between T-piece and ET tube)

6. To lavage: Grasp T-piece with one hand and advance catheter with the other until desired depth is achieved. Instill saline solution through the irrigation port

7. To suction: Depress control valve and apply pressure intermittently. (Note: minimal thumb pressure will activate suction, but maximum suction is achieved when valve is fully depressed)

8. Withdraw and rotate catheter with one hand positioned on control valve while the other remains firmly grasping the T-piece/connector

9. While holding T-piece, retract catheter until catheter mark is visible in the sleeve; avoid overextending the catheter

10. Flush the catheter by instilling solution through the irrigation port white applying suction

11. Turn off wall suction

12. Rotate the thumb control valve 180 degrees to lock suction control in off position

Patients with ET tube Leakage-Type Aspiration. Another problem in intubated ventilator patients is leakage of subglottic secretions past the endotracheal tube cuff. These secretions can contaminate the lower respiratory tract and lead to the development of ventilator-associated pneumonia.

Continuous aspiration of subglottic secretions (CASS) has been shown to reduce the incidence of ventilator-associated pneumonia in these patients. This is accomplished using an ET tube that incorporates a suction lumen above the cuff, with a separate evacuation line and connecting port (see figure to right). Subglottic suction is provided using a standard wall suction unit set to apply continuous low suction not exceeding 20 mm Hg. For safety, The suctioning port should be clearly marked so it is not confused with the cuff pilot balloon.


The last consideration determining the type of suction device used is the goal of removing secretions. If the goal is simply to clear the airway, then select using the above criteria (location, patient size and condition).

On the other hand, there are times when you need to gather a sample of the secretions for laboratory analysis. To do so, select a sputum collection trap (also called Lukens trap). As pictured to the left, a sputum collection trap consists of a collecting vial (usually 30-50 mL) with a screw top that has two short plastic or rubber tubes attached. When removed from its sterile packaging, you connect one tube (the one with the hard taper tip) to the connecting tubing coming from the wall regulator or suction pump. To the other short tube you connect the hard taper tip of the suction catheter. When suctioning, liquid material becomes trapped in the collection vial. When suctioning is complete, you disconnect both the wall suction tubing and the suction catheter fro the trap. You then seal the collection vial by connecting its two short tubes together. The vial is then labeled and placed in the proper container for transport to the laboratory.

Checking and Troubleshooting Suction Devices

To confirm that a suction device is working, you should always check the vacuum pressure before applying it to a patient. If no vacuum is generated at the distal end of the device after connecting it to the suction source, you should check for leaks in the tubing, at the collection container, or the regulator. In addition, if the collecting bottle is full, the float-valve will close and prevent vacuum transmission. When using a sputum collection, you must also be sure that the vial top is screwed on tightly and the all connections are tight. If the leak appears limited to the suction device itself (Yankauer tip, catheter, sputum trap) and cannot easily be corrected, replace the device.

Leaks in closed suction catheter systems on ventilator patients will result in a fall in PIP and volume loss during volume control ventilation, with volume loss and inspiratory flow increases observed with pressure control ventilation. If you confirm that the leak is due to the closed suction catheter system, replace it with a new one. A separate problem with these systems occurs if you fail to fully retract the catheter after suctioning. In this case, airway resistance rises. This causes PIP to increase when using volume control ventilation, while delivered volume will fall with pressure control ventilation. In addition, the patient’ spontaneous work of breathing will increase. To correct this problem, fully retract the catheter until you see the marker.