HFNC for apnoeic oxygenation. The OPTNIV trial.


Apnoeic oxygenation via high-flow nasal cannula oxygen combined with non-invasive ventilation preoxygenation for intubation in hypoxaemic patients in the intensive care unit: the single-centre, blinded, randomised controlled OPTINIV trial, by Samir Jaber et al[1].

 

Among all the interventions we perform daily in our ICUs, from central lines, decisions regarding antibiotics, advanced monitoring techniques, and so on, orotracheal intubation is probably the most important one, probably because the patient could die in a matter of minutes if you inadvertedly delay it, or because of the inherited challenge of the procedure, or due all the bad things that can happen to a intubated patient (VAP, delirium, increased LOS, myopathy, death…). Even today I fell my heart speeding up when I have to assist or perform an intubation. There are so many things that could go wrong. That being said, all aspects we can somehow improve or change to make the intubation act safer, worth some investigation. By the way, Scott Weingart rocked with his podcast series “Laryngoscope as a Murder Weapon” (link). In recent years, specially in the #FOAMed community, lot has been discussed about apnoeic oxygenation, an amazing technique to prevent hypoxemia during intubation attempts. However, the sweet nectar of strong evidence is still missing here. But we are getting there. Today, our purpose is to discuss the Apnoeic oxygenation via high-flow nasal cannula oxygen combined with non-invasive ventilation preoxygenation for intubation in hypoxaemic patients in the intensive care unit: the single-centre, blinded, randomised controlled OPTINIV trial [1], published this year on Intensive Care Medicine.

We all know that the use of non-invasive ventilation (NIV) for preoxygenation can decrease the incidence of severe hypoxemia in patients with severe hypoxemic acute respiratory failure, and how its use has increased (Thanks G.) during the past years. But, even this amazing air propeller device has a downside: you have to take the NIV mask off before intubating the patient, believe me, there is no other way. Unfortunately, at this point, the peripheral oxygen saturation (SpO2) of that 50y/o guy with intrapulmonary shunts all over the place will drop as fast as the Democratic’s expectations about the USA elections. And now, you better get that airway secured. To overcome this adversity, some guys though that would be a good idea to find a way to fill up the lungs with oxygen during the laryngoscopy, a technique called apnoeic oxygenation. Well, a nasal catheter might do the job. In fact, it does. But there is no “Glamour” behind it. But How if we got a device, desperately to find its purpose, like the high-flow nasal cannula oxygen (HFNC) and manage to use it to perform the amazing apnoeic oxygenation technique? Oh boy, this can sell! Jokes aside, the HFNC could add the benefit of apnoeic oxygenation during intubation procedures. So, our French friends decided to run a trial comparing HFNC + NIV vs NIV alone for intubation in hypoxaemic patients.

How

The OPTINIV trial was a single center, randomized, controlled, blinded, proof-of-concept trial, done in a 16-bed mixed ICU in France.

The inclusion criteria were:

– >18y/o

– Requirement of mechanical ventilation

– Severe hypoxemic acute respiratory failure, defined as: RR>30/min AND FiO2 >50% to obtain a SpO2 ≥ 90% AND a P/F ratio <300mmHg, in the 4 hours before inclusion.

The intervention group received 4min preoxygenation with HFNC ( flow= 60 L/min, FiO2 = 100 %) + NIV (PS =10 cmH2O, PEEP =5 cmH2O, FiO2 = 100 %), while the control group received 4min preoxygenation with NIV only (PS =10 cmH2O, PEEP =5 cmH2O, FiO2 = 100 %). Patients were randomized to an 1:1 ratio, the observer collecting the data was blinded (control group patients had the HFNC placed but without any flow). The primary outcome was the minimal SpO2 during the intubation procedure. To detect a difference of 5% in the lowest SpO2, 23 patients were needed in each arm. Both intention-to-treat and per-protocol analysis were planned.

Results

Both groups were pretty similar regarding the baseline characteristics, but whenever you’re dealing with small sample sizes some discrete unbalances always happen. The control group had more intubations during the night than the intervention group (46% vs 32%), more patients in the control group were intubated due COPD exacerbation, the median P/F ratio in the intervention group was lower than the control (107 vs 140), and the median time from induction to secure airway was lower in the control group ( 60s vs 120s). Both groups were similar regarding the number of intubation attempts.

About the primary outcome: intervention group had higher minimal SpO2 than the control group [100 (95–100) % vs. 96 (92–99) %, p = 0.029]. Below, we can see the changes in distribution of SpO2 values during the entire procedure. As predicted, we can see a decrease in control’s SpO2 during the intubation.

The authors also analyzed intubation procedure‐related complications, one patient (4%) in the intervention and five (21%) in the control group had a SpO2 below 80% during the procedure.

Well, the same history of small single center studies apply here, however, things need to start somewhere, this was a proof-of-concept trial and it’s lovely to read research with positive results about potentially game changing interventions, even if the evidence generated is fragile. And although I’m not a big fan of HFNC, the principle of apnoeic oxygenation is pretty elegant and has a good physiological background. Probably, even if we have multicenter trials investigating this issue I don’t think we’ll find any evidence of mortality benefit on general population, therefore, this intervention should be aimed for high risk groups. For now, I think it’s a strategy to keep in mind. Regarding the use of NIV alone, I feel that sooner or later will become standard practice, if the patient has no contra-indications to its use. For myself, if I predict a difficult airway, which is not an easy thing to do, I try to use the apnoeic oxygenation technique whenever is possible, not only because I believe in it (it’s funny to say this when discussing science, but as I told you guys once, this is not an impartial blog, here, we usually defend our ideas while making joke to the things we don’t believe), but because I think it’s a important thing to be taught. Maybe it can save some lives during those late night shift hours.

 

 

1.     Jaber S, Monnin M, Girard M, et al. Apnoeic oxygenation via high-flow nasal cannula oxygen combined with non-invasive ventilation preoxygenation for intubation in hypoxaemic patients in the intensive care unit: the single-centre, blinded, randomised controlled OPTINIV trial. Intensive Care Med. 2016;42(12):1877-1887.

 

 

Photo credit

T Davis 


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HFNC for apnoeic oxygenation. The OPTNIV trial.

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