I took over the care of a 24 weeker who developed PIE at about 5 days of life. Baby was doing well on conventional vent (volume-targeted ventilation), when at day 3 their oxygenation and ventilation began worsening. By day 5, PiPs were in the high 20s/low 30s. By day 6, the decision was made to change to HFOV. 

Our attempts to wean MAP while keeping SpO2 >88% were unsuccessful. We were able to get the MAP from 18 down to 14, but attempts to wean lower resulted in worsening oxygenation. 

At DOL 7, I made the decision that unless we could get the PIE to resolve, we were likely going to lose the baby, so I changed the strategy. Weaning the MAP became the primary concern at the expense of FiO2 and SpO2. I am accepting SpO2 in the 80s and 100% FiO2. I am allowing hypercarbia as long as the pH is >= 7.25 and pCO2 is < 70. This has required a higher amplitude and lower Hz than I would like, but it seems to be working. 

Do any of you have specific experience in treating PIE with HFOV? If so, what worked and what didn't work? How did you manage the Hz/frequency?

I will give an update later today. 

Over the past 3 hours, I have slowly weaned the MAP from 11 to 9. FiO2 has remained 80-90% while SpO2 has been 88 - 91%. Blood gas prior to weaning was 7.31/42/41/21/-5 and the CXR still looked hyperexpanded at a MAP of 11.

Most recent gas on MAP 9, Amplitude of 38 and Hz of 9.5 was 7.13/69.6/45/23/-6, 90% FiO2 and 90% SpO2. I dropped the Hz by 0.5 but left all other parameters as they were. Although the base deficit is slowly worsening, he has brisk capillary refill, is urinating briskly, and is maintaining MBPs >32 mmHg without vasopressors or inotropes, thus his delivery of oxygen has not been severely compromised by accepting lower SpO2. 

Great topic! During my years at the Karolinska NICU, we used HFOV a lot (these days, the SensorMedics was *the* machine), much thanks to my mentor Baldvin Jonsson who was trained by @Martin.Keszler. 

This "low-volume strategy" with HFOV is still the prevailing strategy with airleaks in Stockholm, as far as I know from my level2+ context these days, i.e. reducing pressure as much as possible at the expense of increased FiO2.

Sounds this infant manages well!

 

We had a very similar 24w last year, he was in HFO for several weeks and there are some reports of using either HFJV (which we don’t have in Chile) or HFO with low rates. We used HFO+VG with a target of SpO2 of >80% (or at least to achieve a normal brain rSO2) and pCO2 65-70, using rates of 5-6 Hz to increase expiratory time. He needed dexamethasone and then hydrocortisone for weaning, diuretics for several weeks, and was discharged at 41-42 weeks of CGA with O2 0,1 lpm. Really bad chest xray though, some big bullae.

You are in the right way. HFO fq 5-6 Hz, Amp as high as you see Vibration. Lower MAP as you did, but try do use less, Oxygen max 70%. Permissiv hypercabnia ok. Lay your patient on his dummy. Both sided PIE,  equal? If not: best side up. 

I just started using the jet and I am not impressed by the amount of parameters used and modified

I previously managed those patients the same way you did, great job

A problem that most units would see when looking after babies at the extremes of viability. We have used HFOV + VG (VG 1-3mL/kg) to manage these babies and generally don't have to reduce the frequency below 10Hz. Using "Sigh Breathes" can also be useful in these babies but like another poster suggested, using an early DART course may be useful as well as treating other underlying co-morbidities e.g. anaemia, VAP, PDA etc.

 

This is taken from Prof Jane Pillow's manual on the use of HFOV that is published by Drager. Just thought it would be worth sharing. 

Let us know how you get on with this wee little one!

Richard

 

Thank you everyone for your input. In spite of continuing to lower the MAP, the CXR remains hyperexpanded. Base deficit slowly worsened throughout the day, although BP remained acceptable. The Hct is stable at 45%. I gave 20/kg of isotonic bicarbonate last night for a base deficit of -10, and the pH and base deficit improved. 

Awaiting another CXR this morning, if it still looks hyperexpanded, I will focus more on decreasing Hz. There seems to be some disagreement in what limited literature I can find (mostly opinions) as to whether a Hz of 12-15 or Hz of 6-9 is more beneficial. Anecdotal only, but this baby seems to be responding better to the low Hz strategy. I will get a bit more aggressive about lowering Hz today, then maybe I can start weaning the amplitude as I speculate it may be the culprit of hyperexpansion.

I have used the HFJV in the past to manage PIE, with good results, certainly a much more rapid response than the current case I am managing. However, at my current facility, we do not have a HFJV. Also, we are using the SensorMedics HFOV, which to my knowledge, does not have the ability to do HFOV+VG. 

As to repositioning the baby, we tried this earlier this week with abysmal results. Repositioning on the SensorMedics HFOV is very difficult. 

I will give an update in an hour or two.

I know the Sensormedics well, it is a great machine and with few buttons  I am not aware of any VG addon. The hyperinflation may be related to the PIE as such, maybe you could even reduce the CDP slightly more. My experience with decreasing the Hz is mostly related to management of CO2-retention, but I would def try to lower Hz in this case. Just keep an eye on CO2-levels so you don't end up in hypocarbia.

We got the Hz down to 6, but our first attempt to wean the amplitude resulted in a pretty significant respiratory acidosis.

What is really strange is that in spite of weaning the MAP from its original 14 to now 8, the hyperexapnsion by CXR is getting worse. I speculate that the air leak is not healing at all, and we essentially have thousands of little tension pneumothoraces surrounding what little areas of gas exchange the baby has; I wouldn't really call them alveoli at 24 weeks. 

Awaiting an echo now to assess shunting and see if an argument can be made to increase contractility with milrinone. 

I think that if you go too low in the MAP air trapping could go worse as intrinsic PEEP is higher than your MAP. In my patient we had to use Milrinone to support heart function and norepinephrine in 2 suspected VAP with haemodynamic deterioration. 
Here I send a chest xray of my patient. Good luck! And remember steroids, I think they helped a lot. 

3 hours ago, Miguel Pantoja said:

I think that if you go too low in the MAP air trapping could go worse as intrinsic PEEP is higher than your MAP. In my patient we had to use Milrinone to support heart function and norepinephrine in 2 suspected VAP with haemodynamic deterioration. 
Here I send a chest xray of my patient. Good luck! And remember steroids, I think they helped a lot. 

We started steroids 5 days ago, albeit the low-dose DART protocol of dexamethasone. I am about to start Milrinone and dobutamine to improve cardiac function. Thanks for your input.  

Here is the CXR when the baby's MAP was 12:

 

Here is the CXR when the MAP was 8:

Clearly the hyperexpansion and air trapping are much worse on the second CXR with a lower MAP.

Per  @Miguel Pantoja we increased the MAP from 8 to 10 and have now weaned to 80% with SpO2 in the low 90s. We will continue to wean FiO2 until we reach a nadir, then slowly increase the MAP to a maximum of 12, while trying to wean the amplitude, then we will try and be patient and let the lungs heal if oxygenating and ventilating reasonably well. Ideally, I would like to get the amplitude to no more than 2x the MAP. I have a CXR ordered for the early morning and will try and post it hear to show the difference. 

Truly thankful for everyone who has contributed to this thread. 

Sad day. In spite of our best efforts, we have been unable to get this baby to ventilate and oxygenate. This morning, on a MAP of 10.5, this was the CXR:

Last night we tried a mixture of milrinone and dobutamine to increase cardiac output and open the pulmonary vascular bed, but this made our oxygenation and ventilation worse. We stopped those meds and the baby did fairly well overnight with respect to his blood gases, and we were able to wean the amplitude somewhat. The echo yesterday showed a small PFO shunting left to right, but otherwise, no significant pathology. 

Throughout the morning and the afternoon, his oxygen saturation and ventilation worsened, necessitating we increase his amplitude to levels higher than last night. This was a CXR from the early evening:

As compared to yesterday, the PIE has gone from micro to macro, and the hyperexpansion remains in spite of modest MAPs. This CXR was on a MAP of 11, amplitude of 32 and a Hz of 6. Baby was on 100% FiO2 and saturations were in the 60s. 

During the course of this disease process, I have been retrospectively reviewing the train of events. The mother was admitted with bulging bags at 23 weeks gestation, and in labor. Her labor was stopped with MgSO4 and indocin. She received a full course of betamethasone and was started on antibiotics soon after admission.  Baby delivered vaginally a week later, within intact membranes and was intubated in the delivery room. All resuscitation was performed, surfactant administered, lines in place, antibiotics started, and the top of the isolette was down within 60 minutes. 

Looking at the PiPs, they dropped to low 20s after surfactant, but then began rising again at about 16 hrs of life. The FiO2 was between 21-25% during this time and the MAPs on volume-targeted ventilation (5 mL/kg) remained at around 7 mmHg. PEEP was at 5 mmHg. At 16 hrs of life, the PiPs climbed to the high 20s/low 30s. Because the supplemental FiO2 need was minimal, a second dose of surfactant was not given. Retrospectively, I can see evidence of PIE as early as the second day of life. 

My question today was: should we be basing our administration of surfactant less on FiO2 and MAPs and more on PiPs? Any thoughts?

On 5/29/2020 at 4:21 AM, richmaus said:

This is taken from Prof Jane Pillow's manual on the use of HFOV that is published by Drager. Just thought it would be worth sharing. 

Let us know how you get on with this wee little one!

Richard

 

 

I also believe higher Frequencies should be used in this patient - this is taken from Zannin et al. on the use of different frequencies https://www.nature.com/articles/pr2017151.pdf:

Quote

Much of the pressure applied at the opening of airways is transmitted to the distant lung in infants with low compliance, especially at low frequencies. High frequency should be preferred when using HFOV in infants with low compliance because the high frequency facilitates pressure damping while still achieving the same ventilation obtained at lower tidal volumes.

At lower frequencies - a lot more pressure reaches (and damages) the alveoli. This is dampened a lot more at higher frequencies (>12-15 Hz): so even if you set higher pressures - a lot less reaches the alveoli, but ventilation remains same.

We have used this approach in a few patients. In the end it was a combination of using the minimal ventilation (accepting lower Sats and higher CO2s) acceptable, giving steroids & extubating as soon as possible - even if that necessitated reintubation in some cases. In one sided PIE we have also used thoracic bandaging to limit lung excursions. In two cases we have also resected the destructed lobe to allow for better ventilation of the rest of the lung with success.

Taken from the paper of Zannin et al. You can see that lower set P (pressure) levels at low frequencies lead to a lot higher alveolar pressures than if higher frequencies are used. This means you are injuring the lungs more by using lower frequencies - even if you think you are using lower pressures. In comparison a pressure set at 40 at a freq of 15 Hz leads to lower alveolar pressure.

Hi!

We used the Sensormedics with low-volume-strategy alot in case of pie. Then we we lost a lot of our "old" colleagues and a lot of Knowledge concerning the hfov got lost. I think the sensormedics is a very powerful machine which also can do a lot of harm in inexperienced hands.
Therefore we switched to conventionale mechanical ventilation combined with taping of the chest - we use low tidal volumes, very short insp. time (0,1 - 0,2 s).
We try to establish a stable situation with NAVA as soon as possible (without any evidence, but good experinces).  

On 5/28/2020 at 9:57 PM, LIA GRAVARI said:

I just started using the jet and I am not impressed by the amount of parameters used and modified

Would you care to elaborate?  I found your comment the most interesting one aside from the actual clinical narrative that is

Wonder why;), have you used the jet? It was just an opinion

It merely meant I trained and feel very comfortable with HFOV 

I now work in a unit that idolizes the jet as the best ventilator for really any baby less than 25 weeks 

I don’t mind the new knowledge except there are at least two schools of thought on rate, peep, pip and Sigh breath manipulation which makes it easier for learners to get confused on the right choice 

I have seen really bad PIE, (Never seen it that bad with HFOV), atelectasis and BPD with the above vent-which could be due to decreased understanding of the correct use

I have also failed to find literature that’s strongly urging me to use the jet

of course it might just be that I am “an old dog that can’t learn new tricks”😂

 

 

I understand that it may be a long time ago you had issues w this baby but I would point out couple of things. Hope you weathered the storm and baby survived. It appeared that from the beginning baby had poor chance. It is important to have good recruitment of the lung before you give surfactant. You dont want it to go only to opened alveoli as the ones closed will be very stiff and eventually end up w PIEs. Undoubtedly Jet is superior to HFOV for PIEs. Jet doesn’t ventilate PIE alveoli allowing them to heal. Ask Dr. Keszler for advices when in question. Next, when you cant oxygenate, like last few CXR shown, and kid is hyperexpanded you are decreasing preload and at the same time obstructing  pulmonary flow. You have to drop MAP on HFOV. You need to learn POCUS to look at the heart filling while managing tough cases like this. Also lung US helps a lot. Read Australian and McNamara studies on POC ECHO as well as Kurepa et al. paper on lung US. Finally using higher or lower Hz depends on each baby. See what works for your kid. Remember CXR is just one quick shot in time. All the best.