What’s up doc?

Carrots anyone? This is interesting, but I am afraid I can’t figure out a number of things in the manuscript. The authors report that they randomized 203 babies <33 weeks to get supplemented with carotenoids, they wanted to look at effects on the blood levels of the 3 carotenoids. I am not sure why you would want to do that, surely if you give carotenoids, it would be weird if the carotenoid levels didn’t go up. I guess they were really interested in the secondary outcomes, growth, feeding tolerance and electroretinograms.

Rubin LP, Chan GM, Barrett-Reis BM, Fulton AB, Hansen RM, Ashmeade TL, Oliver JS, Mackey AD, Dimmit RA, Hartmann EE et al: Effect of carotenoid supplementation on plasma carotenoids, inflammation and visual development in preterm infants. J Perinatol 2012, 32(6):418-424.

where it starts to get confusing is in the analysis, of the 203 enrolled infants, they select 183 babies to be the ITT group, 91 controls and 92 supplemented. That is a perversion of the term ‘Intention To Treat’. An ITT analysis includes all of the randomized subjects. It is not clear what was wrong with the other 20 babies, why weren’t they analyzed? The authors supply a Consort flow sheet in the supplemental data, but nowhere on that flow sheet are there 12 controls and 8 supplemented babies who were not analyzed mentioned, the flow sheet introduces even more confusion, there were 70 controls and 73 supplemented who completed the study, but only 50 and 58 of them completed ‘on assigned feeding’. In the results, they state that 52 and 46 infants respectively were ‘evaluable’ which apparently means they strictly adhered to the feeding protocol.

In fact none of the numbers in the flow sheet match the numbers in the text.

The primary outcome variable, that is the blood carotenoid concentrations, wasn’t even measured in most of the infants, at 40 weeks, only 43 controls and 36 supplemented infants had plasma concentrations measured. This is another number that doesn’t appear anywhere else, or in the flow sheets, and is unexplained. To only measure the primary outcome variable on a third of the randomized patients doesn’t sound like good research planning.

Even more bizarre the sample size was calculated as being 68 patients per group, for each of the 3 groups, but there were only 2 groups. The authors talk about a 3rd human milk group in the methods, but they then are very hard to find in the results, and don’t appear at all in the flow sheet. I think what they did was randomize infants to 2 groups, of formulae with or without carotenoids, and then when an infant was receiving a lot of breast milk, they took them out of the assigned group and called them a 3rd group. But the only data presented from them that I can see are the CRP values. The carotenoid concentration comparison group that they show in the figures as the human milk group is from previously unpublished data from Abbott, from term breast fed babies.

The ERG results are from a very small subset of infants, 16 controls and 25 supplemented.

I can’t see any indication that this trial was registered, which most IRBs now insist on, and most journals also require. The Consort flow diagram is missing a lot of information, such as numbers of babies eligible, and doesn’t explain most of the terms.

I was just planning to write a little note to point out this study which might show something, but after re-reading it, the post started growing and growing; I am very confused if they found anything, other than giving carotenoids might increase carotenoid concentrations in the 1/3 of the infants who had them measured.

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Surgeons like probiotics, breast milk, and eating quickly.

…for their patients of course, or to be more accurate, to reduce the chances of small preterm infants becoming their patients. A review of ways to prevent necrotizing enterocolitis, and then to treat it if it occurs, was just published. The authors endorse probiotics, and note the value of breast milk in reducing NEC. They note that feeding preterm babies faster does not increase NEC. The review is quite complete regarding other important issues in the management of NEC,  for all of them the response is unfortunately ‘dunno’.

Downard CD, Renaud E, St Peter SD, Abdullah F, Islam S, Saito JM, Blakely ML, Huang EY, Arca MJ, Cassidy L et al: Treatment of necrotizing enterocolitis: An american pediatric surgical association outcomes and clinical trials committee systematic review. J Pediatr Surg 2012, 47(11):2111-2122.

Here are their questions and the abbreviated version of their answers.
1. Does the use of prophylactic probiotics reduce the rate of NEC in newborn infants? YES
2. Does exclusive use of human breast milk rather than formula affect the rate of NEC in newborn infants? YES
3. Does the rate of feeding affect development of NEC in newborn infants? NO
4. Does peritoneal drainage versus laparotomy as treatment for perforated NEC affect mortality or long-term sequelae, such as neurodevelopmental outcomes and stricture rates? DUNNO
5. Does primary anastomosis at laparotomy versus enterostomy as treatment for NEC affect mortality or long-term sequelae, such as neurodevelopmental outcomes and stricture rates? DUNNO
6. Does length or type of antibiotic treatment affect recurrence rate of NEC? DUNNO

I’m being a bit facetious, but in fact the review is very complete, I think of high quality and well written. If you want a review of all the literature, this would be a very good place to start.

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Hypotension

A new study from the NICHD neonatal network Batton B, Li L, Newman NS, Das A, Watterberg KL, Yoder BA, et al. Use of Antihypotensive Therapies in Extremely Preterm Infants. Pediatrics. 2013 May 6.,This prospective cohort study was specifically designed to look at hypotension treatments, in infants less than 27 weeks gestation during the first 24 hours of life. Of a cohort of 367 babies, the authors found that 55% received at least one therapy for low BP; and, just like the ELGAN study, they found great variation in treatment of hypotension between centres.There was a variety of catecholamines used for treatment, some received hydrocortisone, and one baby received vasopressin.

The authors examined several different definitions of hypotension; despite this they were unable to show much association between hypotension and short term outcomes. In fact infants who were treated for hypotension had worse outcomes than those not treated, in particular intracranial hemorrhage, both overall and the more severe grades, as well as more retinopathy and lower survival.  The lower survival was due to different mortality rates after the first week of life. All of the different outcomes disappeared after statistical adjustment.

Beau Batton and his colleagues end with the following statement ”Until there are data to suggest otherwise, antihypotensive therapy should be used cautiously for these infants because treatment of low BP is associated with similar or worse infant outcomes without evidence of benefit. Large, high-quality studies are needed to support evidence based recommendations for BP management in this population”

Gene Dempsey and I and our collaborators agree! See the HIP trial link on this blog page.

Speaking of which, some of the HIP collaborators have just published this article: Sirc J, Dempsey EM, Miletin J: Cerebral tissue oxygenation index, cardiac output and superior vena cava flow in infants with birth weight less than 1250 grams in the first 48 hours of life. Early Hum Dev 2013, 89(7):449-452. It gives some very interesting normal values (if you can call anything a normal value in a baby who weighs less than 1250g) for cerebral oxygenation and systemic flows over the first couple of days of life. Interestingly even this group, who have a history of interest in ”permissive hypotension ©” treated 20% of the cohort with interventions to raise the blood pressure. Just showing yet again how important it is that we gather some reliable data about how to treat these infants, with what, and at what thresholds of clinical indicators.

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Predicting outcomes in preterm infants: is it time to throw away the ultrasound machine?

It is common practice, nearly universal, I would guess, to perform head ultrasounds in the 1st week of life as a way to predict which very preterm babies will have very poor outcomes, and then to consider redirection of care (an inelegant euphemism for letting the baby die). The American Academy of Neurology guidelines recommend a head ultrasound at 1 week of age, which is sometimes explicitly stated to be for the purpose of “letting the baby die”. What data do we have that this is appropriate, i.e. adequately discriminates between babies with profoundly limited outcomes, and those without?

The short answer is, almost none.

One of the big problems is that the large majority of follow up studies have used Bayley scales of infant development, sometimes other analogous scales, and usually at no more than 3 years of age. The follow up studies I have no problem with, describing our outcomes with the best available tools is appropriate. But then using those gross screening tools to decide which babies lives are worthwhile is very problematic.

I have spoken several times about the limitations of the Bayley, see for example my presentation on predicting outcomes on this blog, the Bayley was designed to screen babies for developmental delay. NOT to decide if their lives were profoundly limited.

A new systematic review Luttikhuizen Dos Santos ES, de Kieviet JF, Konigs M, van Elburg RM, Oosterlaan J. Predictive value of the Bayley Scales of Infant Development on development of very preterm/very low birth weight children: A meta-analysis. Early Hum Dev. 2013 Jul;89(7):487-96  points out how poor the BSID are for predicting later cognitive function. They conclude “MDI scores explain 37% of the variance in later cognitive functioning” which in other words, means that they are about 2/3 useless.

A well-written commentary from a group of physicians from Seattle Children’s hospital discusses the ethics of our current standard approach, and points out how little ethical support there is for what many of us are doing. Mann PC, Woodrum DE, Wilfond BS. Fuzzy Images: Ethical Implications of Using Routine Neuroimaging in Premature Neonates to Predict Neurologic Outcomes. The Journal of pediatrics. 2013 Apr 24. When head ultrasounds are so poorly predictive of long term outcomes, we should reconsider why we do them, and when, and whether they are of any value at all to our patients.

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Neonatal Updates #32

Cevey-Macherel M, Forcada Guex M, Bickle Graz M, Truttmann AC: Neurodevelopment outcome of newborns with cerebral subependymal pseudocysts at 18 and 46 months: A prospective study. Archives of Disease in Childhood 2013. It is not rare to find these cysts. They are found where the germinal matrix used to be, and I thought they were probably of no consequence. This follow up of 74 infants with the cysts is reassuring. But they did find more associated diseases than I would have expected, 8 with congenital CMV, and 9 with other conditions. That is probably more than you would expect for a group of randomly selected infants without the cysts, so a careful evaluation and maybe a routine urine (or saliva) CMV is probably warranted.

Payne AH, Hintz SR, Hibbs AM, Walsh MC, Vohr BR, Bann CM, Wilson-Costello DE, Eunice Kennedy Shriver National Institute of Child H, Human Development Neonatal Research N: Neurodevelopmental outcomes of extremely low-gestational-age neonates with low-grade periventricular-intraventricular hemorrhage. JAMA Pediatr 2013, 167(5):451-459. NICHD network follow up of 270 preterm VLBW infants with grade 1 or grade 2 hemorrhages. Compared to preterm controls with no hemorrhage the low grade hemorrhage had no effect on 18 to 20 month outcomes. That is what we have said to parents for along time, even though there have been some intermittent suggestions that there might be minor effects of these small hemorrhages. this looks like very reliable data. The authors do state that they think that later outcomes should be examined, which is always the right thing to say, but to be honest if the Bayley at 18 months doesn’t show a difference, its very unlikely that later more appropriate tests of cognition are going to show anything.

Rogowski JA, Staiger D, Patrick T, Horbar J, Kenny M, Lake ET: Nurse staffing and nicu infection rates. JAMA Pediatr 2013, 167(5):444-450. The authors tried to examine something which is very difficult to have a good scientific study, but I think they did a really good job. comparing staffing levels to guielines, then measuring the incidence of infection.  I will quote their results ‘Hospitals understaffed 31% of their NICU infants and 68% of high-acuity infants relative to guidelines. To meet minimum staffing guidelines on average would require an additional 0.11 of a nurse per infant overall and 0.34 of a nurse per high-acuity infant. Very low-birth-weight infant infection rates were 16.4% in 2008 and 13.9% in 2009. A 1 standard deviation-higher understaffing level (SD, 0.11 in 2008 and 0.08 in 2009) was associated with adjusted odds ratios of 1.39 (95% CI, 1.19-1.62; P< .001) in 2008 and 1.40 (95% CI, 1.19-1.65; P <.001) in 2009.’

So not enough nurses, more infections.

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Acidosis and the preterm, effects on heart and lungs

Noori S, Wu T-W, Seri I. pH Effects on Cardiac Function and Systemic Vascular Resistance in Preterm Infants. The Journal of pediatrics. 2013;162(5):958-63.e1. This study examined the effects of pH on ventricular outputs and calculated vascular resistance. There was little effect detectable on ‘contractility’ or outputs or SVR in the first few days, but a reduction in SVR with lower pH after the first 3 days, which is accompanied by an increase in systemic flow.
Animal models show different effects of respiratory acidosis and metabolic acidosis, probably largely because of differential effects on intracellular pH, the authors here find no effect of CO2 in the first 3 days, but increasing flow with decreased SVR as CO2 increases thereafter.

I find the study reasssuring, but I am not sure how good we are at measuring true contractility with ultrasound, the indices that are measured are highly derived, nevertheless Noori and colleagues find no effect of pH on contractility.

This may not be very surprising, they quote a review article  Orchard CH, Kentish JC. Effects of changes of pH on the contractile function of cardiac muscle. American Journal of Physiology – Cell Physiology. 1990;258(6):C967-C81. (open access) which examines the mechanisms, if you read it you will notice, on the few occasions that actual pH values are discussed, they show that the major effects of changes in intracellular acidosis are when the pH is less than 7, sometimes as low as 6.6 or even 6.0! There is not much effect in these animal models in general of pH over 7.0.

Nevertheless I think these studies can help us to feel less worried about acidosis in our babies, it is so common for small preterm babies to develop metabolic, mixed and respiratory acidosis. There is probably little effect on cardiac function, certainly my practice, with permissive hypercapnia, is not to worry about high CO2 down to a pH of 7.20, maybe even lower would be OK too.

Where are we now with permissive hypercapnia? When I was a boy… we aimed to keep PCO2 relatively normal in ventilated infants, in the 40’s (mmHg, obviously). Then there was a paper that I was struggling to find until a few minutes ago, I thought the internal RAM in my head had failed me, but I had correctly remembered some details of the study but not the fact that they called it  ‘Mechanical controlled hypoventilation in status asthmaticus.’ It was by Darioli R and Perret C. Am Rev Respir Dis 1984, 129:385-387. This was a case series from an adult ICU with enormously reduced pulmonary trauma when the CO2 was ignored. They only intubated the asthmatic patients if they couldn’t maintain oxygenation; and when they were ventilated the only goal was to maintain an adequate oxygenation, but if the CO2 was very high, they said, ‘so what’. They reported a series of 159 adults with respiratory failure due to asthma with a 100% survival rate, with little barotrauma (pneumothoraces etc). After that, the term permissive hypercapnia was invented and the approach was extended to ARDS with reductions in barotrauma in that condition also.

Case series of patients surviving after very high CO2s showed no apparent long term ill effects and a small series of children who survived after PCO2 greater than 150 showed no ill effects (they called it supercarbia, Goldstein B, Shannon D, Tedres I. Supercarbia in children: Clinical course and outcome. Crit Care Med. 1990 1990;18:166). Permissive hypercapnia became widely accepted in the adult and pediatric ICU.

It must be stated though that not increasing ventilation in order to normalize a CO2 is a reasonable approach, but it still matters how you ventilate a baby. You can damage lungs by ventilating them slowly with very high volumes and still ‘achieve’ a high CO2! Over-distension of the lungs, which usually occurs at end-inspiration, (or atelectasis at end expiration) damages the lungs.

At the same time there was some reluctance to introduce this approach in the newborn, with observational studies associating high CO2 with intracranial hemorrhage in preterm infants.

Wally Carlo has been studying permissive hypercapnia in infants, the trials that he tried to do were difficult to perform, and the separation between permissive and standard groups was not great. But he has now put all of the data together in a review article, Ryu J, Haddad G, Carlo WA. Clinical effectiveness and safety of permissive hypercapnia. Clin Perinatol. 2012;39(3):603-12. They note that there is some evidence of beneficial effects of hypercapnia in acute illness, and the clinical neonatal studies have been reassuring regarding safety. I don’t know if we will ever get the large RCT of permissive hypercapnia, it will have to be designed to use appropriate ventilation with attempts to avoid overdistension in both groups, and allow the permissive group to have higher CO2, but protocolize how the ventilation is increased in the low (normal) CO2 group in order to bring the CO2 below a certain limit. It would be tough to do. 

In the meantime not pushing ventilation to achieve arbitrary CO2 goals, as long as acidosis is not too severe, seems reasonable, and is probably safe.

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Global Choir

That last post reminded me of something that I saw a couple of years ago, that, if you haven’t seen it is well worth a view. I love this, Eric Whitacre, an American composer, invited people from all over the world to send videos of themselves singing one of his compositions, and then put them all together in this amazing piece.

http://www.youtube.com/watch?v=6WhWDCw3Mng

I just found out that he did the same thing a third time, about 1 year ago, and that he now found funding (via kickstarter) for version 4. Here is number 3.

http://www.youtube.com/watch?v=V3rRaL-Czxw

Anyone who wants to be part of number 4 can keep an eye out for the notices and instructions  and then record over the internet, just like all those who were part of 1, 2 and 3.

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More Hadfield

One of the videos from Chris Hadfield that I really loved is this one, http://www.youtube.com/watch?v=AvAnfi8WpVE a duet with some of the Bare Naked Ladies (also Canadian!) and a choir of young people.

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A Space Oddity

The Canadian astronaut Commander Chris Hadfield returned to Earth today. He was the first astronaut of the new internet age, in terms of the way he used his earthbound links. As someone born in the 1950’s (yes I know it is hard to believe) to me, the idea of someone circling the earth on a space station sending pictures and videos to his twitter followers is beyond belief. Yet it happened, His final video was a rendition of a David Bowie favourite, you may remember that David Bowie has already made an appearance on this blog, as Colm O’Donnell used a song title of his as the title of an article he wrote (Ch Ch Ch Changes…) http://www.guardian.co.uk/science/blog/2013/may/13/chris-hadfield-the-astronaut-s-best-tweets-photos-and-videos  During his months on the Space Station, Chris Hadfield sent many fabulous photos on his social media feeds, The Guardian page that the above link leads you to has many of his best.  This fragile Earth, seen from a new angle.

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SUPPORT: even better than originally thought

Public Citizen are at it again, repeating and expanding their idiotic criticisms of the SUPPORT trial. And stating that the trial was ‘even worse than originally thought’. They are now focusing on the ‘problem’ that the NICUs used ‘intentionally inaccurate’ pulse oximeters.

The most disturbing finding from our review of the newly available information was the failure of half of the IRB-approved consent forms to disclose to the parents of the subjects the experimental procedure, under which the entire medical team caring for each premature baby in the study was intentionally given inaccurate information about the baby’s blood oxygen saturation levels by using pulse oximeters miscalibrated across the wide range of oxygen saturations between 85% and 95%. Of note, oxygen saturation measured by a pulse oximeter is a clinical parameter of such importance in monitoring critically ill patients that it is sometimes referred to as the “fifth vital sign.

Because of the inaccurately high oxygenation saturation values provided to the medical team by the pulse oximeters for babies in the low-oxygen experimental group, it is plausible that the medical team may have treated some critically ill babies with too little oxygen, potentially resulting in brain injury and death secondary to hypoxemia (deficient oxygen). In contrast, because of the inaccurately low oxygenation saturation values provided to the medical team by the pulse oximeters for babies in the high-oxygen experimental group, it is also plausible that the medical team may have treated those babies with more oxygen than they needed, resulting in severe retinopathy of prematurity, requiring surgery and possibly causing blindness. What we do not know because the study lacked a usual standard of care control group, but suspect, is that if the medical teams had been given the correct information about oxygen saturation levels and these babies had been treated based on their individual needs as per current routine standard of practice, some deaths might have been prevented in the low-oxygen group, and some cases of severe retinopathy might have been prevented in the high-oxygen group.

This is the core of the new ‘concerns’ raised by Public Citizen, and all they really show is the ignorance of the authors about how neonatology works.

For any readers who are also unaware, we choose saturation limits based on NICU protocols not on individual prescribed values. We have no data from which to prescribe individual limits, that is why we did these studies. Yes the saturations were offset by 3%, the only way to make this a masked study. And no this did not make being in the study more dangerous, in fact being in the study was less dangerous than being in the NICU and not in the trial. So in contrast to what they state, that there was no ‘usual standard of care control group’, there were many babies in the NICUs who were not enrolled in the trial, and were treated according to usual NICU practice, who had a higher mortality than the babies in SUPPORT. Let me also explain that in our unit at the time we allowed saturations to be between 84 and 95%. That is including both of the ranges of saturation that were tested in SUPPORT, we thought that that entire range was safe, and that being in the lower part was probably safer, we now know, only as a result of SUPPORT, BOOST2 AusNZ, BOOST2 UK, and COT, that we were wrong. That babies who were not in the trial were at higher risk, that the lower part of that range, which is where most NICUs were heading before these trials, is associated with increased mortality.

Later in the public citizen document they state

Understanding the clinical importance of oxygen saturation levels in the routine management of premature babies is essential for recognizing the serious risks of providing protocol-specified misinformation to the NICU medical teams that cared for the infants in the SUPPORT study

This is almost humorously ironic, as the authors of this document clearly don’t understand the importance of saturation monitoring, and how we had no idea which saturations to target prior to the trial.

The  authors of this report, one of which appears to be an adult nephrologist who does some lab research, another a Bioethicist, the 3rd another MD but I am unsure what he does, go on to pontificate about how we look after extremely preterm infants. A subject on which they are unqualified, and misinformed. They don’t even seem to know how pulse oximeters work!

Given the complexities of routine medical management of extremely premature infants and the interaction between the different complex experimental interventions of the SUPPORT study, the minimization of the risks to babies enrolled in the study would have required a detailed plan for unblinding the NICU medical teams when the masking procedure using intentionally miscalibrated pulse oximeters posed a threat to the health of the babies.

If, in the course of any study, the physician feels that the study procedures are putting a patient at risk, or course the patient needs to be taken out of the study. In some circumstances it is important to know what treatment the patient has been receiving, and to unmask the study. In this particular study all you needed to do was to use an ordinary pulse oximeter. Indeed, that was done a few times, a doctor thought that a baby with pulmonary hypertension, for example, and treated the baby with higher saturation targets, using an unadulterated oximeter, unmasking would not be necessary.

The reason that happened very rarely is that we do not fix individual saturation targets in the NICU. They are set by protocol.

Protocols which were arbitrary, based on guesses, and many of those guesses were wrong.

I guess the authors of this document think that all of the investigators in SUPPORT, all of the investigators in the other trials around the world are unethical, and don’t really care about preterm babies. Maybe if they stopped to consider that they are maligning hundreds of people who have dedicated their lives to looking after small newborn babies it would make them reconsider their ill-conceived and slanderous attacks.

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