Israel Medical Association Journal

Background: Optimal oxygen supply is the cornerstone of the management of critically ill patients after extubation, especially in patients at high risk for extubation failure. In recent years, high flow oxygen system devices have offered an appropriate alternative to standard oxygen therapy devices such as conventional face masks and nasal prongs.

Objectives: To assess the clinical effects of high flow nasal cannula (HFNC) compared with standard oxygen face masks in Intensive Care Unit (ICU) patients after extubation.

Methods: We retrospectively analyzed 67 consecutive ventilated critical care patients in the ICU over a period of 1 year. The patients were allocated to two treatment groups: HFNC (34 patients, group 1) and non-rebreathing oxygen face mask (NRB) (33 patients, group 2). Vital respiratory and hemodynamic parameters were assessed prior to extubation and 6 hours after extubation. The primary clinical outcomes measured were improvement in oxygenation, ventilation-free days, re-intubation, ICU length of stay, and mortality.

Results: The two groups demonstrated similar hemodynamic patterns before and after extubation. The respiratory rate was slightly elevated in both groups after extubation with no differences observed between groups. There were no statistically significant clinical differences in PaCO₂. However, the use of HFNC resulted in improved PaO₂/FiO₂ post-extubation (P < 0.05). There were more ventilator-free days in the HFNC group (P < 0.05) and fewer patients required re-intubation (1 vs. 6). There were no differences in ICU length of stay or mortality.

Conclusion: This study demonstrated better oxygenation for patients treated with HFNC compared with NRB after extubation. HFNC may be more effective than standard oxygen supply devices for oxygenation in the post-extubation period.

Background: Valved holding chambers with masks are commonly used to deliver inhaled medications to young children with asthma. Optimal mask properties such as their dead space volume have received little attention. The smaller the mask the more likely it is that a greater proportion of the dose in the VHC[1] will be inhaled with each breath, thus speeding VHC emptying and improving overall aerosol delivery efficiency and dose. Masks may have different DSV[2] and thus different performance.

Objectives: To compare both physical dead space and functional dead space of different face masks under various applied pressures.

Methods: The DSV of three commonly used face masks of VHCs was measured by water displacement both under various pressures (to simulate real-life application, dynamic DSV) and under no pressure (static DSV).

Results: There was a great variability of both static and dynamic dead space among various face mask for VHCs, which is probably related to their flexibility.

Conclusions: Different masks have different DSV characteristics. This variability should be taken into account when comparing the clinical efficacy of various VHCs.