Samantha Holton outlines 2025 NHSN ventilator‑associated event surveillance guidance

Samantha Holton, presenter, reviewed the National Healthcare Safety Network’s 2025 guidance for ventilator‑associated event (VAE) surveillance in a webinar, covering definitions, the three‑tier VAE algorithm, reporting rules, and tools for determinations.

Holton emphasized the algorithm’s structure: "The VAE identified is then reported at the highest tier of the algorithm that is met." The three tiers are ventilator‑associated condition (VAC), infection‑related ventilator‑associated complication (IVAC), and possible ventilator‑associated pneumonia (PVAP). VAC is determined by objective deterioration in oxygenation after at least two days of stability or improvement; IVAC adds abnormal temperature or white blood cell counts plus a new antimicrobial continued for at least four qualifying antimicrobial days (QADs); PVAP requires microbiologic or histopathologic evidence from eligible respiratory specimens.

Why it matters: Holton said the VAE definition was developed to improve objectivity and automation in surveillance and to capture a broader set of adverse events than ventilator‑associated pneumonia (VAP), which can be subjective when interpreting radiographs. She noted a 2015 CDC point‑prevalence survey finding that pneumonia was the most common hospital‑acquired infection in the sample and that 35% of those pneumonias were ventilator‑associated.

Key detection thresholds and timing: To meet VAC, surveillance compares daily minimum values of FiO2 and PEEP from calendar day to calendar day (not within‑day values). A VAC is flagged when either the daily minimum FiO2 increases by at least 20 percentage points sustained for two calendar days or the daily minimum PEEP increases by at least 3 centimeters of water sustained for two calendar days. Holton described the daily minimum as the lowest value maintained for greater than one hour (or, if none maintained ≥1 hour, the lowest recorded value).

Holton explained event timing rules: the earliest date of event is Day 3 of mechanical ventilation; the VAE window period is usually five days (the two days before the date of event, the date of event, and the two days after) used to assess IVAC and PVAP elements; and the VAE 14‑day event period (date of event through day 14) prevents reporting a second VAE during that interval. She also reviewed exceptions when the window is shortened (for events on ventilation Days 3–4) and the transfer rule for location attribution when a transfer occurs on or just before the date of event.

Antimicrobial rules and QADs: Holton detailed that an antimicrobial is “new” if it was not given on either of the two days preceding the current start date and was initiated within the VAE window; qualifying antimicrobial days count consecutive days a new agent was administered (with limited allowed gaps for the same agent) and can include different agents if each is new. She used calculator examples to show agents started before the VAE window are not considered new for IVAC determination.

PVAP and laboratory interpretation: Holton said PVAP Criterion 1 is met by quantitative or appropriate semi‑quantitative culture thresholds from eligible specimens (endotracheal aspirate, bronchoalveolar lavage, lung tissue, protected specimen brush). If labs report semi‑quantitative results, she advised asking laboratory leadership to map those results to the protocol thresholds, and referenced VAE FAQs and Table 2 for guidance about interpreting purulence and direct exam formats. She cautioned that meeting IVAC does not prove a respiratory origin and that the antimicrobial list was refined to remove agents unlikely to treat lower respiratory infection.

Reporting and denominators: Holton instructed facilities to report all detected events when VAE surveillance is included in the facility’s monthly reporting plan and to report events at the highest tier met (report VAC only if VAC is the highest tier met, IVAC if VAC+IVAC met, PVAP if all tiers met). Required denominator data are ventilator days and patient days, collected at the same time each day; ventilator days count all patients on a ventilator at the time of the daily count, including those ventilated fewer than three days or on excluded therapies.

Tools and practical steps: Holton urged use of NHSN tools—the VAE Calculator, VAE Data Collection Worksheet, and antimicrobial worksheet—and demonstrated that "The calculator does not store any data that you enter because it is run locally on your computer, and it will not report any entered data or VAE determinations to NHSN." She recommended establishing relationships with respiratory therapy, critical care, and laboratory staff to standardize collection of daily minima and interpretation of lab reports.

Holton closed by reiterating the stepwise surveillance workflow—determine daily minima, identify VAC and the date of event, set the VAE window, review temperature/WBC and antimicrobial QADs, then review lab results for PVAP—and pointed attendees to the VAE webpage, protocol, and FAQs for further detail. The webinar concluded after the presentation portion.