How to Suction a Patient: Step-by-Step Procedure

Suctioning an intubated or tracheostomized patient means threading a sterile catheter into the artificial airway and applying negative pressure to remove accumulated secretions that the patient cannot clear on their own. Done well, the procedure takes roughly 10 to 15 seconds of actual suction time and keeps the airway open. Done poorly, it can cause tissue damage, dangerous drops in oxygen levels, and heart rhythm disturbances. The difference between a safe pass and a harmful one comes down to preparation, technique, and knowing when to stop.

Recognizing When a Patient Needs Suctioning

Suctioning should be performed only when clinical signs suggest the patient has secretions blocking the airway, not on a fixed schedule. Audible gurgling or rattling sounds during breathing, visible secretions in the endotracheal or tracheostomy tube, a sudden rise in peak airway pressures on the ventilator, a drop in oxygen saturation, or a sawtooth pattern on the flow-volume loop all point to the need for suctioning. A randomized trial in a pediatric ICU compared as-needed suctioning against routine scheduled suctioning and found no significant difference in adverse events or the length of time children spent on mechanical ventilation, supporting the practice of suctioning based on patient assessment rather than the clock.¹

Before you begin, a quick bedside check helps you anticipate problems. Note the patient’s current heart rate, blood pressure, oxygen saturation, and respiratory rate. If the patient has a brain injury, check their intracranial pressure reading. Patients on high ventilator settings or those who are hemodynamically unstable need extra caution because suctioning will temporarily remove them from positive-pressure ventilation (in open systems) and can provoke cardiovascular swings.

Choosing the Right Equipment

Catheter size matters more than most clinicians realize. The suction catheter’s outer diameter should occupy less than half the inner diameter of the endotracheal tube. Exceeding that threshold can cause excessive negative pressure inside the airway, leading to lung collapse (atelectasis) and dangerous drops in oxygen levels.² A bench-top study simulating adult patients with acute respiratory distress syndrome confirmed that going above the 50 percent ratio destabilized the positive end-expiratory pressure the ventilator was delivering, which in sick lungs can undo the ventilation strategy entirely.³

For a typical adult with an 8.0 mm endotracheal tube, a 12 or 14 French catheter usually falls within the safe range. Pediatric and neonatal tubes are much smaller, so the catheter must be proportionally smaller as well. Beyond catheter size, set the wall suction to the lowest effective pressure. For neonates, an integrative review recommended keeping negative pressure below 100 mmHg.⁴ In adults, most guidelines suggest pressures between 80 and 150 mmHg, using the minimum that effectively clears secretions. Higher pressures pull more secretion but also strip more mucosa from the airway walls.

Preoxygenation Before You Start

Every pass of the suction catheter temporarily removes gas from the lungs, so preoxygenation acts as a safety buffer. Increasing the fraction of inspired oxygen to 100 percent for a brief period before suctioning builds up an oxygen reserve. A study comparing different durations found that 30 seconds of preoxygenation led to a significantly greater drop in arterial oxygen saturation during and after suctioning than either one minute or two minutes of preoxygenation. The researchers recommended at least one minute of preoxygenation before each suctioning event to avoid clinically relevant desaturation.⁵

Hyperoxygenation after suctioning is equally important. In a clinical implementation study, patients who received 100 percent oxygen both before and after suctioning maintained stable saturation readings, with one patient’s saturation dipping briefly to 93 percent during catheter insertion before recovering to 99 percent within a minute of post-suctioning hyperoxygenation.⁶ After suctioning is complete, return the oxygen to its baseline level promptly. Leaving a patient on 100 percent oxygen longer than necessary can promote absorption atelectasis, where the lungs’ nitrogen is replaced by oxygen that the blood absorbs too quickly, causing small areas of lung to collapse.⁷

The Procedure Step by Step

Once equipment is ready and the patient has been preoxygenated, the actual suctioning follows a consistent sequence. Open the suction catheter packaging using sterile technique, don sterile gloves (for open suctioning), and connect the catheter to the suction tubing without yet applying negative pressure. During open suctioning, sterile technique is the standard of care.⁸

Insert the catheter gently into the artificial airway without applying suction. The catheter should advance no farther than the tip of the endotracheal or tracheostomy tube, reaching just to the carina (the point where the trachea splits into the two main bronchi) or slightly above it. Apply suction only as you withdraw the catheter, rotating it gently between your fingers. The entire suction pass should last no longer than 15 seconds from start to finish.⁹ If secretions remain after the first pass, re-oxygenate the patient and allow heart rate and saturation to recover before making another attempt. Limit the number of catheter passes per suctioning event, as the risk of complications climbs with each successive pass.

After the final pass, reconnect the patient to the ventilator or oxygen source, return the inspired oxygen to the pre-suctioning level once saturation has stabilized, and reassess the patient. Listen for breath sounds, note the amount and character of secretions, and check that the ventilator waveforms have returned to normal.¹⁰ Document the procedure, including the color, consistency, and volume of secretions, how the patient tolerated it, and any changes in vital signs.

Why Suctioning Depth Matters So Much

One of the most consequential decisions during suctioning is how far to advance the catheter. “Deep” suctioning, where the catheter passes beyond the tip of the endotracheal tube and touches or passes the carina, used to be standard practice. Evidence accumulated over decades has shown it causes significantly more harm than a shallow, premeasured technique. An early animal study using young rabbits found that deep suctioning caused significantly more necrosis, inflammation, loss of cilia, and excess mucus production compared to shallow suctioning, leading the researchers to recommend that neonatal units abandon deep suctioning for routine care.¹¹

More recent clinical data reinforces that finding in adults. A study comparing deep versus shallow tracheal suctioning in mechanically ventilated patients found that tracheal tissue injury occurred in all patients who received deep suctioning compared to roughly half of those who received shallow suctioning. The deep technique also produced significantly more hypoxemia and cardiac rhythm disturbances: about a quarter of patients in the deep group experienced abnormal heart rhythms, compared to under 7 percent in the shallow group.¹² The practical takeaway is straightforward: premeasure the catheter insertion depth so it reaches the tip of the tube without going beyond it.

Open Versus Closed Suctioning Systems

In an open system, you disconnect the patient from the ventilator, insert a single-use catheter, suction, withdraw the catheter, and reconnect. In a closed system, the catheter lives inside a protective sleeve attached inline to the ventilator circuit, so you never disconnect the patient. Each approach has trade-offs, and the evidence on which is better is genuinely mixed.

A Cochrane systematic review that pooled data from 11 trials found no significant difference between the two systems in rates of ventilator-associated pneumonia, mortality, or length of ICU stay. Interestingly, the closed system was associated with higher rates of bacterial colonization of the airway.¹³ A later meta-analysis reached a different conclusion, finding that open suctioning increased the incidence of ventilator-associated pneumonia by about 57 percent compared to closed suctioning.¹⁴ Meanwhile, another comparative study in an emergency medicine setting found no significant difference in pneumonia rates, duration of ventilation, length of stay, or mortality between the two methods.¹⁵

Where closed systems clearly shine is in patients who depend on continuous positive airway pressure to keep their lungs open. Because the ventilator circuit stays intact, there is less loss of lung volume during suctioning. An experimental evaluation showed that open suctioning without any positive pressure caused marked drops in oxygen saturation and tracheal pressure, while closed suctioning with positive pressure maintained during the procedure resulted in considerably fewer side effects.¹⁶ For patients with severe lung disease, brain injury, or very high ventilator settings, closed suctioning is generally preferred for this reason. For patients on lower settings who are more hemodynamically stable, either system can be appropriate.

Should You Instill Saline Before Suctioning?

For decades, nurses routinely squirted a few milliliters of normal saline into the endotracheal tube before suctioning, believing it would loosen thick secretions and make them easier to remove. This practice persists in many units despite growing evidence that it does more harm than good. A systematic review and meta-analysis found that saline instillation was associated with decreased oxygen saturation, prolonged recovery time for saturation to return to baseline, decreased arterial pH, and increased heart rate and blood pressure. The one potential benefit, a reduced incidence of ventilator-associated pneumonia in some studies, did not outweigh the accumulated harms.¹⁷

A multimethod study found that despite the evidence against it, nearly 88 percent of surveyed nurses still used saline instillation.¹⁸ The gap between evidence and practice here is striking. Current guidelines recommend against routine saline instillation. If secretions are too thick to suction effectively, better strategies include adequate systemic hydration, humidification of the ventilator circuit, and occasionally mucolytic agents rather than pouring fluid directly into the airway.

Continuous Versus Intermittent Suction Application

Some practitioners were taught to apply suction in short intermittent bursts during catheter withdrawal, while others use continuous suction throughout. An experimental study examining tracheal tissue under both methods found that both continuous and intermittent application of negative pressure produced significant tissue damage, with no meaningful difference between the two techniques.¹⁹ A comprehensive evidence review recommended continuous suctioning over intermittent, reasoning that if both cause similar tissue changes, continuous suction at least clears secretions more efficiently and allows the procedure to be completed faster.⁹ The key variable for reducing tissue injury is not the pattern of suction but rather the pressure level and the duration of the pass.

Complications and How to Prevent Them

Suctioning is one of the most commonly performed procedures in intensive care, and precisely because it is so routine, the risks can be underestimated. The major complications fall into a few categories.

Hypoxemia is the most common adverse effect. Every pass of the catheter removes not just secretions but also gas from the lungs, and in open systems the patient is briefly disconnected from their oxygen source. The strategies already discussed, preoxygenation, limiting pass duration to 15 seconds, and using the smallest effective catheter, all directly target this risk.

Cardiovascular insturbances are the second major concern. Suctioning stimulates the vagus nerve, which can slow the heart rate dramatically. In a case series of tetraplegic patients, tracheal suctioning induced significant bradycardia in all four patients, and two experienced cardiac arrest. The bradycardia was triggered by a vagal reflex compounded by hypoxia and the absence of sympathetic nervous system activity in these spinal cord-injured patients. Preoxygenation prevented the response in some cases, and atropine was effective when oxygen alone was not enough.²⁰ Even in patients without spinal cord injuries, suctioning can provoke a drop in heart rate. In one study, heart rate fell from an average of 114 beats per minute to 45 beats per minute during suctioning in susceptible patients, a life-threatening change.²¹ Monitoring heart rate throughout the procedure and stopping immediately if significant bradycardia develops is essential.

Raised intracranial pressure is a particular danger for patients with brain injuries. A study of patients with severe head injuries found that intracranial pressure rose significantly during suctioning, and the increase grew worse with each successive catheter pass.²² A review of the literature noted that most studies showed intracranial pressure climbing above 20 mmHg, a clinically dangerous threshold, when open suctioning was used in neurologically impaired adults.²³ In these patients, minimizing the number of catheter passes, using closed suctioning, and sedating adequately before the procedure are standard precautions.

Suctioning at Home With a Tracheostomy

Suctioning is not exclusively an ICU procedure. Thousands of patients, particularly children with tracheostomies, require routine suctioning at home. The technique follows the same core principles: preoxygenate when possible, use a catheter sized appropriately for the tracheostomy tube, insert without suction applied, apply suction only on withdrawal, and limit the duration. Clean technique rather than full sterile technique is generally accepted in the home setting, since the environment is not sterile to begin with and the patient’s own airway flora is already established.

What families often struggle with is not the mechanics of the procedure but the confidence to perform it and the judgment to know when something is going wrong. A program that combined respiratory care training with telemedicine follow-up for families of tracheostomized children operated on the principle that better caregiver skills in airway care would reduce infection rates and hospital readmissions.²⁴ Home caregivers should have a portable suction machine, backup catheters, and a clear plan for when to call emergency services, such as when secretions are bloody, when the tracheostomy tube cannot be cleared despite repeated suctioning, or when the patient shows signs of respiratory distress that do not improve after the procedure.

Common Mistakes Even Experienced Clinicians Make

Suctioning is taught early in clinical training and then rarely revisited formally, which allows bad habits to calcify. A few of the most persistent errors deserve mention.

Suctioning on a schedule: Performing the procedure every two hours “just in case” exposes patients to repeated airway trauma without clinical benefit. Assess first, suction only when indicated.
Advancing the catheter until resistance is felt: This was once standard teaching. It means you have hit the carina or a bronchial wall, and you are now suctioning living tissue. Premeasure your depth instead.
Using excessive suction pressure: Turning the wall suction up to clear thick secretions faster trades a short-term gain for mucosal damage. If secretions are too thick at appropriate pressures, address the cause by improving humidification.
Skipping preoxygenation for “quick” passes: Even a brief pass without preoxygenation can drop saturation in a fragile patient. The buffer takes one minute to establish and prevents the most common complication of the procedure.
Instilling saline out of habit: The persistence of this practice despite contrary evidence suggests it has become a ritual rather than a clinical decision. Abandoning it is one of the simplest evidence-based improvements available.

Each of these errors reflects a broader pattern: suctioning is invasive, and every element of the procedure, from catheter size to insertion depth to the seconds of applied suction, should be treated with the same rigor as any other invasive airway intervention. The fact that it happens many times a day in busy ICUs does not make it benign.