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Gentle ventilation must start from birth


Gentle ventilation must start from birth

The lungs of a preterm infant are so fragile that over time pressure limited time cycled ventilation has given way to volume guaranteed (VG) or at least measured breaths.  It really hasn’t been that long that this has been in vogue.  As a fellow I moved from one program that only used VG modes to another program where VG may as well have been a four letter word.  With time and some good research it has become evident that minimizing excessive tidal volumes by controlling the volume provided with each breath is the way to go in the NICU and was the subject of a Cochrane review entitled Volume-targeted versus pressure-limited ventilation in neonates. In case you missed it, the highlights are that neonates ventilated with volume instead of pressure limits had reduced rates of:

death or BPD



severe cranial ultrasound pathologies

duration of ventilation

These are all outcomes that matter greatly but the question is would starting this approach earlier make an even bigger difference?

Volume Ventilation In The Delivery Room

I was taught a long time ago that overdistending the lungs of an ELBW in the first few breaths can make the difference between a baby who extubates quickly and one who goes onto have terribly scarred lungs and a reliance on ventilation for a protracted period of time.  How do we ventilate the newborn though?  Some use a self inflating bag, others an anaesthesia bag and still others a t-piece resuscitator.  In each case one either attempts to deliver a PIP using the sensitivity of their hand or sets a pressure as with a t-piece resuscitator and hopes that the delivered volume gets into the lungs.   The question though is how much are we giving when we do that?

High or Low – Does it make a difference to rates of IVH?

One of my favourite groups in Edmonton recently published the following paper; Impact of delivered tidal volume on the occurrence of intraventricular haemorrhage in preterm infants during positive pressure ventilation in the delivery room. This prospective study used a t-piece resuscitator with a flow sensor attached that was able to calculate the volume of each breath delivered over 120 seconds to babies born at < 29 weeks who required support for that duration.  In each case the pressure was set at 24 for  PIP and +6 for PEEP.  The question on the authors’ minds was that all other things being equal (baseline characteristics of the two groups were the same) would 41 infants given a mean volume < 6 ml/kg have less IVH compared to the larger group of 124 with a mean Vt of > 6 ml/kg.  Before getting into the results, the median numbers for each group were 5.3 and 8.7 mL/kg respectively for the low and high groups.  The higher group having a median quite different than the mean suggests the distribution of values was skewed to the left meaning a greater number of babies were ventilated with lower values but that some ones with higher values dragged the median up.


IVH < 6 mL/kg > 6 ml/kg p
1 5% 48%  
2 2% 13%  
3 0 5%  
4 5% 35%  
Grade 3 or 4 6% 27% 0.01
All grades 12% 51% 0.008

Let’s be fair though and acknowledge that much can happen from the time a patient leaves the delivery room until the time of their head ultrasounds.  The authors did a reasonable job though of accounting for these things by looking at such variables as NIRS cerebral oxygenation readings, blood pressures, rates of prophylactic indomethacin use all of which might be expected to influence rates of IVH and none were different.  The message regardless from this study is that excessive tidal volume delivered after delivery is likely harmful.  The problem now is what to do about it?

The Quandry

Unless I am mistaken there isn’t a volume regulated bag-mask device that we can turn to to control delivered tidal volume.  Given that all the babies were treated the same with the same pressures I have to believe that the babies with stiffer lungs responded less in terms of lung expansion so in essence the worse the baby, the better they did in the long run at least from the IVH standpoint.  The babies with the more compliant lungs may have suffered from being “too good”.  Getting a good seal and providing good breaths with a BVM takes a lot of skill and practice.  This is why the t-piece resuscitator grew in popularity so quickly.  If you can turn a couple dials and place it over the mouth and nose of a baby you can ventilate a newborn.  The challenge though is that there is no feedback.  How much volume are you giving when you start with the same settings for everyone?  What may seem easy is actually quite complicated in terms of knowing what we are truly delivering to the patient.  I would put to you that someone far smarter than I needs to develop a commercially available BVM device with real time feedback on delivered volume rather than pressure.  Being able to adjust our pressure settings whether they be manual or set on a device is needed and fast!

Perhaps someone reading this might whisper in the ear of an engineer somewhere and figure out how to do this in a device that is low enough cost for everyday use.




Recommended Comments

Glad you presented this issue. It has been festering in me for over 45 years.

The BVM has been in the delivery room and at the bedside even before  neonatologists existed. The standard approach to a distressed infant was to vigorously “bag him up” to relieve immediate symptoms. The original Baby Bird ventilators had a resuscitation bag incorporated within the ventilator circuit to allow for “bagging up” the infant whenever heart rate dropped or desaturation seemed likely (prior to pulse oximetry). An unacceptably high rate of pneumothoraces and associated barotrauma prompted Bird to remove the resuscitation bag from subsequent Baby Bird models.  There is ample evidence to support the notion that the BVM may be the sole cause of infant CLD. Certainly there are contributing factors that predispose the immature lung to be susceptible to overdistension. Other than congenital emphysema, however, one would be hard pressed to document a case of CLD in which the infant had not received BVM ventilation.

Columbia Presbyterian neonatal unit has shown an unusually low incidence of CLD as compared to most other hospitals. The practice of adopting Dr Wung’s “bubble CPAP” and low pressure and/or low volume ventilation has led to improvement in neonatal outcomes in many hospitals, but matching Columbia Presbyterian’s results has been an elusive goal for most. A possible reason is that others have failed to adopt the delivery room and neonatal unit discipline instilled by Dr Wung that accompanies the practices they’ve adopted. “Give the baby a chance” is Dr Wung’s mantra. The first apgar is at one minute,  not at 20 seconds. This simple act reduces unnecessary interventions and subsequent iatrogenic actions. Outcomes improve. Immediate CPAP application to premature infants is a second action rather than resorting to BVM “rescue”. Again, “Give the baby a chance”.

Refer to Dr Jobe at Cincinnati Children’s article, “Don’t just do something, stand there!” 

Follow-up care in the NICU is equally fraught with iatrogenic actions prompted by good intentions. Infants receiving mechanical ventilation are routinely “bagged up” for desaturation or bradycardia episodes. Again, the immature lung is subjected to stresses it simply cannot tolerate. There are few, if any, studies on how often and to what extent BVM interventions happen. Virtually every study of neonatal mechanical ventilation is skewed by this glaring oversight.

Until the role of BVM is thoroughly investigated and quantified, progress in neonatal CLD will continue to be elusive.

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