# Intracuff Water Droplet Accumulation Occurring Around Eight Hours in Polyurethane-Cuffed Endotracheal Tubes: An In Vitro Simulation Study

## TL;DR

This study finds that water droplets form inside PU-cuffed endotracheal tubes after about eight hours of humidified ventilation, which could affect cuff pressure monitoring in ICU patients.

## Contribution

The study identifies the specific timing of water droplet accumulation in PU-cuffed tubes under simulated ICU conditions.

## Key findings

- Water droplets first appeared in PU-cuffed tubes after approximately eight hours of exposure.
- No water accumulation was observed in PVC-cuffed tubes under the same conditions.
- Fluid migration into the inflation line and pilot balloon was noted in PU-cuffed tubes.

## Abstract

Introduction

Ventilator-associated pneumonia (VAP) is a major complication in intensive care unit (ICU) patients, often resulting from microaspiration due to poor cuff sealing. Polyurethane (PU)-cuffed tracheal tubes, with thinner walls than conventional polyvinyl chloride (PVC) cuffs, offer improved sealing. However, their high water permeability can lead to intracuff water droplet accumulation, potentially interfering with accurate cuff pressure monitoring. This study aimed to determine the timing of water droplet formation in PU cuffs under simulated ventilatory conditions.

Methods

An in vitro simulation was conducted using six tracheal tubes (two each of PU-cuffed Microcuff™ (Kimberly-Clark Health Care, Roswell, GA), PU-cuffed Parker Flex-Tip™ (Parker Medical, Highlands Ranch, CO), and PVC-cuffed TaperGuard™ (Covidien (Medtronic), Mansfield, MA)). Tubes were exposed to heated, humidified airflow for 24 hours at a mean temperature of 39.8 ± 0.4°C and 88 ± 4.6% humidity. Cuff pressure was maintained at 25 cmH₂O. Hourly inspections for visible intracuff water droplets were performed.

Results

Visible water droplets first appeared at eight hours in all PU-cuffed tubes, with a mean onset of 8.25 hours. Fluid migration into the inflation line and pilot balloon was also observed. No water accumulation was seen in the PVC-cuffed tubes. No structural cuff damage was noted.

Conclusion

Water droplet accumulation in PU-cuffed tracheal tubes occurs around eight hours after exposure to humidified ventilation. This early condensation may impair cuff pressure accuracy, posing a safety risk in ICU settings. Clinicians should consider this when managing airway devices and cuff pressures in patients with PU-cuffed tubes.