호흡기내과 R1. 이정미

INTRODUCTION Acute respiratory failure (ARF) is the most common reason for admission in the intensive care unit (ICU), often requiring endotracheal intubation and the institution of mechanical ventilation. Several devices : high-concentration reservoir mask, simple face mask, Venturi mask, and nasal cannula. Venturi mask –when the patient’s inspiratory flow exceeds the gas flow rate from the mask, room air is entrained. –The final concentration of oxygen truly delivered to the patient can be lower than the set FIO2

INTRODUCTION Nasal high-flow (NHF) device –fully humidified, high-flow oxygen (up to 60L/min) through a nasal cannula. –has the potential to improve oxygenation as compared with conventional low-flow systems for oxygen therapy, such as the Venturi mask. We performed a randomized, controlled trial comparing NHF with the Venturi mask in critically ill patients requiring oxygen therapy after extubation, with the hypothesis that NHF could improve oxygenation. We also assessed the effects of the two devices on patient comfort, adverse events, and clinical outcome.

METHODS The study was conducted in two Italian ICUs (Rome and Novara) Exclusion criteria : age less than 18, pregnancy, tracheostomy, do-not- intubate status, and planned use of noninvasive ventilation (NIV) after extubation. At the time of extubation, all patients had a normal mental status and none of them had delirium. After extubation, patients were randomized to receive oxygen through the Venturi mask (control group) or the NHF (intervention group).

METHODS Arterial blood gases, SaO2, F IO2SET, respiratory rate, mean arterial pressure, heart rate, and patient discomfort were recorded at 1, 3, 6, 12, 24, 36, and 48 hours Primary endpoint : oxygenation (i.e., the P aO2 /F IO2SET at 24 h) Secondary endpoints : patient discomfort, episodes of device displacement, episodes of oxygen desaturation, occurrence of postextubation ARF requiring any form of ventilator support, and reintubation.

RESULTs Between November 2010 and April 2011 NIV = noninvasive ventilation.

RESULTs

RESULTs – RESPIRATORY and HEMODYNAMIC PARAMETERs Significantly higher with NHF at 24, 36, 48hrs. Significantly greater with the NHF system than with the Venturi mask at all time steps. Always lower with the NHF Always significantly lower with the NHF system ＊ Heart rate and mean arterial blood pressure were always similar between groups.

RESULTs – PATIENT DISCOMFORT Significantly lower with the NHF system from the 12th hour significantly lower with NHF from the 24th hour * As compared with the Venturi mask, use of the NHF was associated with a lower discomfort related to mouth dryness, throat dryness, difficulty to swallow and throat pain.

RESULTs – ADVERSE EVENTs and CLINICAL OUTCOMEs 109 episodes of interface displacement : 20 episodes in the NHF vs 89 in the Venturi mask (P<0.001) 218 episodes of oxygen desaturation : 40 episodes with the NHF vs 178 with the Venturi mask (P<0.001)

NIV = noninvasive ventilation. RESULTs – ADVERSE EVENTs and CLINICAL OUTCOMEs ⇒ P < 0.001

DISCUSSION Main results (1)Use of the NHF after extubation results in better oxygenation for the same set FIO2 (2)NHF decreases respiratory rate and improves patient discomfort both related to the interface and to symptoms of airways dryness (3)Use of the NHF is associated with fewer episodes of interface displacement and of oxygen desaturation (4)Use of the NHF in the postextubation period is associated with less need for NIV and endotracheal intubations than the Venturi mask.

DISCUSSION – STUDY LIMITATION 1.Masking of patients and personnel to treatment was not performed because it was obviously not possible 2.We did not measure the true FIO2 delivered to patients and we cannot exclude that FIO2 was indeed greater with the NHF than with the Venturi mask. 3.Asessment of patient discomfort was subjective. 4.All patients had an arterial blood gas collected at the end of the successful spontaneous breathing trial, immediately before extubation.

DISCUSSION – CONCLUSIONs As compared with the Venturi mask, the use of the NHF system in the postextubation period results in better oxygenation for the same set FIO2 The NHF decreases PaCO2 and the respiratory rate, while improving patient comfort and reducing episodes of interface dislodgement and oxygen desaturation