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Martin.Keszler

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Martin.Keszler last won the day on March 12

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About Martin.Keszler

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  • First name
    Martin
  • Last name
    Keszler
  • Gender
    Male
  • Occupation
    Neonatologist
  • Affiliation
    Women and Infants Hospital of Rhode Island
    Alpert Medical School of Brown University
  • Location
    Providence, RI
  1. Effect of instrumental dead space.pdfEffect of instrumental dead space.pdfYour first option is the correct one (I assume that though you asked about a 400g baby you used 0.5 kg in your calculations, so we really are dealing with a 500g baby). In any case, the effect of the added dead space is already figured into the approx. 6ml/kg. The concept of dead space is a bit relative. It has an effect, but not as large as you would think if conventional physiology strictly applied. There clearly is some admixture of fresh gas and dead space gas so adding the entire dead space to the calculation would result in overventilation. Please see the following publications that address this issue: Nassabeh - Montazami S, Abubakar K, Keszler M. The Impact of Instrumental Dead-space in Volume Targeted Ventilation of the Extremely Low Birth Weight Infant. Pediatr Pulmonol. 2009;44:128-33. Keszler M, Brugada M, Abubakar K. Effective Ventilation at Conventional Rates With Tidal Volume Below Instrumental Dead Space: A Bench Study. Arch Dis Child Fetal-Neonatal Edition 2012;97:F188–F192 Hurley EH, Keszler M. Effect of inspiratory flow rate on the efficiency of carbon dioxide removal at tidal volumes below instrumental dead space. Arch Dis Child Fetal Neonatal Ed. 2017;102:F126-F130. doi: 10.1136/archdischild-2015-309636. PubMed PMID: 27515984. Cheers, Martin Effect of instrumental dead space.pdf Effect of flow rate on CO2 elimin ADC FN 2016-Hurley.pdf
  2. @spartacus007: Sorry for slow response. Yes we would use AC and avoid heavy sedation. Only use paralysis if despite good NG tube placement we are unable to keep gut decompressed, meaning we use it rarely. Evidence-free zone, for the most part, but muscle relaxation has many downsides and I am a believer in making the baby breathe as much as they can, which minimizes intrathoracic pressure and adverse hemodynamic consequences of PPV. As for SPO2 target, the goal is NOT 100%. Gentle support with minimal PIP needed to get the heart rate up and SPO2 into the low 90s. Generally start with FiO2 around 0.6 and wean if SPO2 is >92-93%. @bimalc : We do not use cuffed tubes, though it would be appropriate if you did not have a ventilator that has excellent leak compensation capability, like the Draeger VN 500, which can accurately compensate for leak of up to 60-70%. If you have a leak anywhere near that large, the baby need a larger tube. @tarek: I love the HFOV + VG. It works very nicely, but in the USA, the HFOV option is not yet approved by the FDA, so I was only able to use it in the context of our preeemie study that will hopefully lead to approval. Given that CO2 removal with HFOV is proportional to F x VT squared, the ability to maintain a constant VT in the face of changing lung compliance is particularly attractive. In my 27 babies we used it on it worked beautifully! Cheers, Martin
  3. "We also start on AC-VG. We bring the ventilator into the delivery room and once intubated, get them on to volume ventilation and avoid as much t-piece or bag ventilation as possible. Initial settings are PEEP 5-6, 4-5mL/kg tidal volume, back up rate of 40, and iTime 0.3" Nathan's approach above is a lot more evidence-based than the earlier post from Winnipeg. There is good evidence that relatively low PEEP should be used to avoid over-expansion of the hypoplastic lungs, which contributes to PPHN (Guevorkian, et al, J Pediatrics 2018). The results of the VICI trial also strongly indicate that high distending pressure is detrimental. For some reason (maybe someone will comment on the rationale, I can't think of one) the investigators chose to use an aggressive lung recruitment strategy with HFOV and a gentle, low PEEP strategy with conventional ventilation. The outcomes favored conventional ventilation over HFOV, but that is because the WRONG strategy was used with HFOV, IMHO, not because HFOV is inherently bad for CDH. We looked at the VT needed to keep a normal PCO2 in CHD and found it to be 4.5 ml/kg. These were data from fairly long ago, when we targeted normal PCO2 in low 40s (Sharma, et al, Am J Perinatol. 2015). 4ml/kg is probably appropriate when aiming for mild permissive hypercapnia. Babies with CDH have the same rate of metabolic CO2 production as any other baby that size, so they need roughly the same alveolar minute ventilation, even if their lungs are small. 3ml/kg would be unlikely to work, since that is the volume of anatomical and instrumental dead space. But I know people who use 3ml/kg because you have a large ETT leak and are not using leak compensation, so that the real VT is around 4ml/kg, but they don’t realize it. Thanks, Martin Keszler MD Professor of Pediatrics, Brown University
  4. I think they work, but at least here in the USA they are not available in small enough size to be useful for small preemies. Are smaller LMs available in Europe? Thanks, Martin Keszler MD Professor of Pediatrics Brown University
  5. John, I have collected some data on this subject with colleagues from Japan and Poland, who have been using HFOV with VG on the VN 500. We have two abstracts at the PAS meeting in Vancouver on this very subject, so please come to Vancouver and find out. Or read the abstracts when they come out. The data are focusing on what VT is needed for normocapnia, not specifically on safety, because using VG should increase safety of HFOV by avoiding inadvertent hyperventilation. Stay tuned, Martin Martin Keszler, Brown University, Providence, RI
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