Many patients in the intensive care unit (ICU) receive oxygen through a breathing
machine. Doctors, nurses, and respiratory therapist adjust the amount of oxygen given
through the breathing machine to target oxygen levels, but the ideal oxygen level to target
is unknown. To understand which oxygen level is best for patients, we conducted a
research study called the PILOT study. A total of 2,541 patients on breathing machines in
the Vanderbilt intensive care unit participated in the study and had their clinicians target
an oxygen level of 90%, 94%, or 98%. The results of the study suggested that patients
did equally well when their clinicians targeted an oxygen level of 90%, 94%, or 98%.
Background: Invasive mechanical ventilation in critically ill adults involves adjusting
the fraction of inspired oxygen to maintain arterial oxygen saturation. The oxygen-
saturation target that will optimize clinical outcomes in this patient population remains
unknown.

Methods

In a pragmatic, cluster-randomized, cluster-crossover trial conducted in the
emergency department and medical intensive care unit at an academic center, we
assigned adults who were receiving mechanical ventilation to a lower target for oxygen
saturation as measured by pulse oximetry (Spo2) (90%; goal range, 88 to 92%), an
intermediate target (94%; goal range, 92 to 96%), or a higher target (98%; goal range, 96
to 100%). The primary outcome was the number of days alive and free of mechanical
ventilation (ventilator-free days) through day 28. The secondary outcome was death by
day 28, with data censored at hospital discharge.

Results

A total of 2541 patients were included in the primary analysis. The median number of ventilator-free days was 20 (interquartile range, 0 to 25) in the lower-target group, 21 (interquartile range, 0 to 25) in the intermediate-target group, and 21 (interquartile range, 0 to 26) in the higher-target group (P = 0.81). In-hospital death by day 28 occurred in 281 of the 808 patients (34.8%) in the lower-target group, 292 of the 859 patients (34.0%) in the intermediate-target group, and 290 of the 874 patients (33.2%) in the higher-target group. The incidences of cardiac arrest, arrhythmia, myocardial infarction, stroke, and pneumothorax were similar in the three groups.

Conclusions

Among critically ill adults receiving invasive mechanical ventilation, the number of ventilator-free days did not differ among groups in which a lower, intermediate, or higher Spo2 target was used.

ClinicalTrials.gov Identifier:
NCT03537937.
Manuscript Title: Oxygen-Saturation Targets for Critically Ill Adults Receiving
Mechanical Ventilation
Journal: New England Journal of Medicine

PMID: 36278971

When patients need a breathing machine, a breathing tube is placed through the mouth and into the windpipe. During placement of the breathing tube, patients may experience serious problems with low oxygen levels. Doctors give oxygen through a mask before the procedure to prevent low oxygen levels. Two types of oxygen mask are commonly used, non-invasive ventilation and facemask oxygen. Both provide oxygen. Non-invasive ventilation also provides positive pressure to open the lungs and provide breaths when a patient’s breathing slows or stops. Both types of masks are FDA approved and both are frequently used in emergency department (ED) and intensive care unit (ICU). The PREOXI study focused on determining if one type of mask is better than the other.

Importance

Among critically ill adults undergoing tracheal intubation, hypoxemia increases the risk of cardiac arrest and death. Before the PREOXI Trial, the effect of preoxygenation with noninvasive ventilation, as compared with preoxygenation with an oxygen mask, on the incidence of hypoxemia during tracheal intubation was uncertain.

Objective

To determine the effect of preoxygenation with noninvasive ventilation, as compared with preoxygenation with an oxygen mask, on the incidence of hypoxemia during tracheal intubation among critically ill adults. Design, setting, and participants: the PRagmatic trial Examining OXygenation prior to Intubation (PREOXI) was a multi-center, parallel-group, non-blinded, randomized clinical trial among 1,301 patients undergoing tracheal intubation in 24 emergency departments and intensive care units across the United States.

Interventions

Patients were randomly assigned to receive preoxygenation with either noninvasive ventilation (n=645) or an oxygen mask (n=656). Main outcomes and measures: the primary outcome was hypoxemia during intubation, defined by an oxygen saturation of less than 85% during the interval between induction of anesthesia and 2 minutes after tracheal intubation. The secondary outcome was the lowest oxygen saturation during the interval between induction of anesthesia and 2 minutes after tracheal intubation.

Results

Among the 1,301 patients enrolled, hypoxemia occurred in 57 patients (9.1%) in the noninvasive ventilation group and in 118 (18.5%) in the oxygen- mask group (difference, -9.4 percentage points; 95% confidence interval [CI], – 13.2 to -5.6; P<0.001). Cardiac arrest occurred in 1 patient (0.2%) in the noninvasive-ventilation group and in 7 patients (1.1%) in the oxygen-mask group (difference, -0.9 percentage points; 95% CI, -1.8 to -0.1_> Aspiration occurred in 6 patients (0.9%) in the noninvasive-ventilation group and in 9 patients (1.4%) in the oxygen-mask group (difference, -0.4 percentage points; 95% CI, -1.6 to 0.7).

Conclusions and relevance:

Among critically ill adults undergoing tracheal intubation, preoxygenation with noninvasive ventilation resulted in a lower incidence of hypoxemia during intubation than preoxygenation with an oxygen mask.

ClinicalTrials.gov Identifier: NCT05267652
Manuscript Title: Noninvasive Ventilation for Preoxygenation during Emergency
Intubation

Journal: New England Journal of Medicine
PMID: 38869091