Background

Ventilator-associated Pneumonia

VAP is a lung infection that develops 48 hours or more after initiating invasive mechanical ventilation. Mechanical ventilation assists breathing in patients who have weak respiration and cannot independently breathe sufficiently to remain alive. Examples of invasive mechanical ventilation techniques include endotracheal intubation and tracheostomy. In endotracheal intubation, a physician places a long ETT in the patient's trachea (windpipe) through the mouth. In tracheostomy, the trachea is accessed through a small incision on the patient's neck. Tracheal secretion accumulation during intubation is a high risk factor for VAP, which can be caused by lung and lower respiratory tract colonization with microorganisms. Patients who need mechanical ventilation after a diagnosis of underlying severe hospital-acquired pneumonia or those with preexisting pneumonia or an underlying condition that causes pneumonia do not meet the criteria for VAP. In critically ill patients, VAP risk factors include prolonged mechanical ventilation, patient characteristics and comorbidities, and prior use of antibiotics. (For more information, see the UpToDate article Clinical Presentation and Diagnostic Evaluation of Ventilator-associated Pneumonia and the article by Wu et al. 2019.)

VAP is common complication that occurs in intensive care unit patients and is a high-risk factor for patient mortality. Timely diagnosis is vital to prevent VAP incidence and antibiotic overuse. Physicians diagnose VAP using a combination of clinical and imaging findings. Gradual or sudden onset of pulmonary infiltrates may be observed during chest imaging. Clinical VAP symptoms include fever, increased respiratory rate, decreased oxygenation, and purulent sputum. Microbiological assessment of respiratory samples to identify associated pathogens is key in VAP diagnosis, treatment, and management. In patients who received endotracheal intubation, VAP preventive measures include daily monitoring of the ETT's cuff pressure, patient head alignment, maintaining oral hygiene, and SSD for secretion removal. (For more information, see the UpToDate articles Clinical Presentation and Diagnostic Evaluation of Ventilator-associated Pneumonia and Risk Factors and Prevention of Hospital-acquired and Ventilator-associated Pneumonia in Adults and the article by Papazian et al. 2020.)

Endotracheal Tubes with Subglottic Secretion Drainage Ports

SSD ports used with ETTs are designed to facilitate continuous or intermittent subglottic secretion removal to lower VAP risk. Newer-generation tubes are designed with a small hole in the rear, a channel running through the tube, and connection to a suction port. The design is intended to prevent subglottic secretion pooling, assist in secretion drainage, and prevent leakage into the lungs to avoid microbial growth that can lead to VAP. Unlike older ETT models, some of the newer devices with SSD ports also have a barrel shape and low-pressure and high-volume cuffs intended to help lower the risk of secretion pooling. Preventing VAP purportedly reduces antibiotic use, length of hospital stay, and overall morbidity and mortality, all of which also depend on surgery complexity, disease etiology, and underlying comorbidities. Manufacturers supply ETTs with SSD ports that are sterile, made of different materials (e.g., polyurethane, polyvinyl chloride), and in multiple cuff sizes and inner tube diameters. (For more information, see the U.S. Agency for Healthcare Research and Quality document Benefits of Subglottic Secretion Drainage Endotracheal Tubes: Facilitator Guide, the website for the Microcuff Adult Endotracheal Tube, the website for the Sacett Suction Above Cuff Endotracheal Tube, and the website for the Shiley Evac Endotracheal Tube with TaperGuard Cuff.)

Clinical Literature

Search dates: January 1, 2017, through July 18, 2022. We reviewed full text of two SRs with meta-analysis (one was reported in two publications [original and erratum]) and two RCTs. These publications reported on 3,907 unique patients.

We searched PubMed, EMBASE, and selected web-based resources for documents relevant to this topic. Our search strategies included the following keywords: subglottic secretion drainage, ventilator associated pneumonia. Please see the Selected Resources and References section for detailed search strategies.

Study selection criteria: We sought comparative clinical studies that reported on VAP incidence in patients who underwent mechanical ventilation using ETTs with and without SSD ports. We selected the best available evidence, which consisted of SRs that meta-analyzed RCTs. We also included RCTs published after the search dates specified in the included SRs. We excluded nonrandomized comparative studies because of the availability of higher-quality studies (i.e., RCTs). We also excluded less comprehensive SRs and studies described as comparisons that assessed different SSD port procedures, protocols, or ETTs made of different materials because they did not report on patient-oriented comparisons of interest.

To avoid double-counting patients, we reviewed the most comprehensive or recent of any two publications with patient overlap; however, we included SRs with overlapping RCTs if they reported on different outcomes of interest. We excluded studies with fewer than 10 patients per arm and conference abstracts.

We identified and reviewed full text of two SRs and two RCTs. The 2 SRs with meta-analyses had an overlap of 9 RCTs (i.e., 1,250 of 3,757 patients overlapped).

Included SRs:

• 1 SR (Pozuelo-Carrascosa et al. 2022a) reviewed 9 existing SRs with meta-analyses and then performed an updated meta-analysis of 20 RCTs ([Erratum: Pozuelo-Carrascosa et al. 2022b] n = 3,757). The SR compared VAP risk ratio of patients who had ETTs with and without SSD ports for mechanical ventilation.(1,2) We identified but excluded an overlapping SR (Rahimibashar et al. 2019) that did not report comparative outcomes.(3)
• 1 SR with meta-analysis (Huang et al. 2018, 9 RCTs, n = 1,250) compared ETTs with and without SSD ports for mechanical ventilation in patients who were admitted to intensive care units. Although this SR included 9 of the 20 RCTs in the Pozuelo-Carrascosa et al. SR (2020a, 2020b), we included it because it also reported on specific microorganisms associated with VAP incidence.(4)

RCTs published after the SRs' search dates:

• 1 single-center RCT (Mahmoodpoor et al. 2020, n = 90) compared an ETT with SSD port (TaperGuard Evac, Medtronic plc., Dublin, Ireland, n = 45) with a silver-coated ETT (Bactiguard, Tullinge, Sweden, n = 45) in adults requiring mechanical ventilation for >48 hours and reported on VAP incidence.(5)
• 1 single-center RCT (Gunjan et al. 2018, n = 60) compared an ETT with SSD port (n = 30) and a conventional ETT (n = 30) in adults who underwent neurosurgery and required mechanical ventilation for >48 hours. The study reported on VAP incidence.(6)

See Table 1 and 2 for study summaries. We review full text of the included studies available through open access or our library subscriptions.

Findings

We assessed two SRs with meta-analyses (one reported in two publications [original and erratum]) and two RCTs that addressed ETTs with SSD ports' capability for mechanical ventilation and reported on VAP.

Evidence from the SR with meta-analyses of RCTs consistently shows lower VAP incidence in patients who received ETTs with SSD ports for mechanical ventilation than those who received conventional ETTs. See details below.

VAP incidence:

• The most recent SR (Pozuelo-Carrascosa et al. 2022a and b) reviewed 9 other SRs with meta-analyses and performed an updated meta-analysis of 20 RCTs. In the updated meta-analysis, authors reported lower VAP risk in patients who received ETTs with SSD ports for mechanical ventilation than patients who received conventional ETTs (risk ratio 0.60, 95% confidence interval [CI] 0.53 to 0.68, I² = 0%). Authors further noted that these results were consistent with the nine prior meta-analyses they analyzed.(2)
• The Huang et al. 2018 meta-analysis reported on gram-positive cocci and Haemophilus influenzae-associated VAP in patients and found a lower VAP incidence in patients who underwent mechanical ventilation using ETTs with SSD ports than in those who received conventional ETTs (OR 0.29, 95% CI: 0.18 to 0.48). Huang et al. 2018 also found no statistically significant difference in nonfermentative bacteria-associated and enterobacteria-associated VAP incidence between groups that received ETTs with SSD ports and groups that received conventional ETTs for mechanical ventilation (odds ratio 0.73, 95% CI: 0.53 to 1.01).(4)
• A small RCT published after these meta-analyses found no difference in VAP incidence between groups receiving ETT with or without an SSD port (Gunjan et al. 2018, clinical VAP 12% [3/25] versus 20% [5/25], p = 0.70, microbiological VAP 44% [11/25] versus 52% [13/25], p = 0.78).(6)

ETT with SSD port versus silver-coated ETT:

• A small, single-center RCT (Mahmoodpoor et al. 2020) reported no statistically significant difference in VAP incidence between an ETT with SSD port group and silver-coated ETT group (20% [9/45] versus 31% [14/45], p = 0.227).(5)

Evidence limitations: Neither of the two small RCTs we reviewed provide conclusive results due to small sample size, single- center focus, and moderate risk of bias. The RCTs in the SRs we reviewed had either a low or unclear risk of bias for each of six potential bias domains examined. Included RCTs were performed in different countries, assessed patients with different etiologies who underwent different surgical procedures, and ETT use was part of bundled VAP preventive measures. These factors may affect generalization and interpretation of results. Additional larger, multicenter RCTs that report VAP from comparisons of ETTs with SSD ports and conventional ETTs, antimicrobial agent-coated ETTs, and ETTs with SSD ports from different manufacturers would be useful to validate findings.  

Table 1. Systematic Reviews

Table 2. Randomized Controlled Trials

Guidelines, Position and Consensus Statements

Searched PubMed, EMBASE, and ECRI Guidelines Trust® (EGT) for relevant documents published January 1, 2017, through July 18, 2022. We identified two documents.

We sought guidelines that are clearly supported by published SRs or included in EGT, a publicly available online repository of guidelines supported by SRs and developed by nationally and internationally recognized medical organizations and specialty societies. These guidelines must meet certain U.S. National Academy of Medicine criteria. We found no guidelines on ETT with SSD ports supported by SRs.

• Chinese Medical Association. Chinese Guidelines for the Diagnosis and Treatment of Hospital-acquired Pneumonia and Ventilator-associated Pneumonia in Adults (2018 Edition). 2019. The consensus statement states:

The [ETT] with subglottic suction can reduce the incidence of VAP, and decrease the length of ICU stay…. It is recommended to use such an [ETT] in the patients who are expected to undergo invasive ventilation for more than 48 or 72 hours … (IA [evidence level and recommendation grade]). The cuff pressure should be kept at 25 cmH2O or higher (IA). The subglottic secretions should be removed as clean as possible before balloon deflation or extubation.

• Society for Healthcare Epidemiology. Infectious Diseases Society of America. Association for Professionals in Infection Control. Strategies to Prevent Ventilator-associated Pneumonia, Ventilator-associated Events, and Nonventilator Hospital-acquired Pneumonia in Acute-care Hospitals: 2022 Update. 2022. The document states:

The following interventions may lower VAP rates, but current data are insufficient to determine their impact on duration of mechanical ventilation, length of stay, and mortality.

Consider using [ETTs] with [SSD] ports to minimize pooling of secretions above the endotracheal cuff in patients likely to require >48–72 hours of intubation (Quality of Evidence: MODERATE).

This intervention uses [ETTs] with [SSD] ports (Quality of Evidence: LOW).] has not been studied in children and is only feasible for children aged ≥10 years because the smallest available [ETTs] with [SSD] ports is size 6.0.