Using the printed word to treat apnea of prematurity

Using the printed word to treat apnea of prematurity

As the saying goes, sometimes less is more.  In recent years there has been a move towards this in NICUs as the benefits of family centred care have been shown time and time again.  Hi tech and new pharmaceutical products continue to develop but getting back to the basics of skin to skin care for many hours and presence of families as an integral team member have become promoted for their benefits.  The fetus is a captive audience and hears the mother’s heart beat and voice after the development of hearing sometime between 24-26 weeks gestational age.  This is a normal part of development so it would stand to reason that there could be a benefit to hearing this voice especially after hearing has developed and the fetus has grown accustomed to it.  Hospital including my own have developed reading programs for our patients and some companies have developed speakers in isolettes designed to limit the maximum decibel to 45 but allowing parents to make recordings of their voices.  Music may be played through these speakers as well but today we will focus on the benefit of voice.

Could reading to your baby reduce apnea of prematurity?

This is the question that Scala M et al sought to answer in their paper Effect of reading to preterm infants on measures of cardiorespiratory stability in the neonatal intensive care unit.  This was a small prospective study of the impact of parental reading on cardiorespiratory stability in preterm NICU infants. Eighteen patients were enrolled who were born between 23-31 weeks gestation.  The study was carried out when the babies were between 8-56 days old at a mean postnatal age of 30 weeks. Each patient served as their own control by comparing episodes of oxygen desaturation to <85% during pre-reading periods (3 hours and 1 hour before) to during reading and then 1 hour post reading.  Parents were asked to read or create a recording lasting a minimum of 15 min but up to 60 min of recorded reading.  The parents were offered a standard set of books that had a certain rhythm to the text or could choose their own.  Recorded reading was played for infants up to twice per day by the bedside nurse. While it was small in number of patients the authors point out that the total exposure was large with 1934 min of parental bedside reading analyzed (range 30–270 min per infant, mean 123, median 94 min).  Patients could be on respiratory support ranging from ventilators to nasal cannulae.

Was it effective?

It certainly was. I should mention though that the authors excluded one patient in the end when it was found that they failed their hearing screen.  Arguably, since the infant could not have benefited from the intervention effect this makes sense to me.  As shown from table 3 there was a statistical reduction in desaturation events during the reading period which was sustained in terms of a downward trend for one hour after the intervention was completed.  In case you are asking was the difference related to oxygen use the answer is no.  There was no difference in the amount of oxygen provided to patients.  While the events were not eliminated they were certainly reduced.  The other point worth mentioning is that there appears to be a difference between live (through open portholes) vs prerecorded reading (through a speaker in the isolette).

Now for a little controversy

Does source of the reading matter?  The authors found that maternal had a greater effect than paternal voice.  As a father who has read countless books to his children I found this a little off-putting.  As a more objective critic though I suppose I can buy the biologic plausibility here.  I suspect there is an independent effect of voice having a positive impact on development.  If we buy the argument though that the voice that the fetus has most been accustomed to is the mothers, then the findings of an augmented effect of the maternal voice over fathers makes some sense.  I will have to put my ego aside for a moment and acknowledge that the effect here could be real.

There will no doubt need to be larger studies done to drill down a number of questions such as what is the ideal type of reading, duration, rhythmic or non etc but this is a great start.  I also think this falls into the category of “could this really be a bad thing?”.  Even if in the end no benefit is shown to this type of intervention, the potential for family bonding with their preterm infant alone I think is cause for embracing this intervention.

Lastly, with the move to single patient rooms there is one study that demonstrated the isolation encountered from infrequent contact with their newborn can have a long lasting effect on development.  The article by Pineda RG et al Alterations in brain structure and neurodevelopmental outcome in preterm infants hospitalized in different neonatal intensive care unit environments. had a mean parental visitation of 19 +/- 19 hours a week or a little over 2 hours a day but with a very large standard deviation meaning many infants had almost no visitation.  The message here is that while quiet is good for infant development, too much can be a bad thing.  Maybe live reading or even recordings are a way around that.

Don’t let the cord gas fool you

Don’t let the cord gas fool you

It has to be one of the most common questions you will hear uttered in the NICU.  What were the cord gases?  You have a sick infant in front of you and because we are human and like everything to fit into a nicely packaged box we feel a sense of relief when we are told the cord gases are indeed poor.  The congruence fits with our expectation and that makes us feel as if we understand how this baby in front of us looks the way they do.

Take the following case though and think about how you feel after reading it.  A term infant is born after fetal distress (late deceleration to as low as 50 BPM) is noted on the fetal monitor.  The infant is born flat with no heart rate and after five minutes one is detected.  By this point the infant has received chest compressions and epinephrine twice via the endotracheal tube.  The cord gases are run as the baby is heading off to the NICU for admission and low and behold you get the following results back; pH 7.21, pCO2 61, HCO3 23, lactate 3.5.   You find yourself looking at the infant and scratching your head wondering how the baby in front of you that has left you moist with perspiration looks as bad as they do when the tried and true cord gas seems to be betraying you.  To make matters worse at one hour of age you get the following result back; pH 6.99, pCO2 55, HCO3 5, lactate 15.  Which do you believe?  Is there something wrong with the blood gas analyzer?

How Common Is This Situation

You seem to have an asphyxiated infant but the cord gas isn’t following what you expect as shouldn’t it be low due to the fetal distress that was clearly present?  It turns out, a normal or mildly abnormal cord gas may be found in asphyxiated infants just as commonly as what you might expect.  In 2012 Yeh P et al looked at this issue in their paper The relationship between umbilical cord arterial pH and serious adverse neonatal outcome: analysis of 51,519 consecutive validated samples. The authors sampled a very large number of babies over a near 20 year period to come up with a sample of 51519 babies and sought to pair the results with what they knew of the outcome for each baby.  This is where things get interesting.  When looking at the outcome of encephalopathy with seizures and/or death you will note that only 21.71% of the babies with this outcome had a gas under 7.00.  If you include those under 7.10 as still being significantly distressed then this percentage rises to 34.21%.  In other words almost 66% of babies who have HIE with seizures and/or death have a arterial cord pH above 7.1!  The authors did not look at encephalopathy without seizures but these are the worst infants and almost 2/3 have a cord gas that you wouldn’t much as glance at and say “looks fine”

How do we reconcile this?

The answer lies in the fetal circulation.  When an fetus is severely stressed, anaerobic metabolism takes over and produces lactic acid and the metabolic acidosis that we come to expect.  For the metabolites to get to the umbilcal artery they must leave the fetal tissues and enter the circulation.  If the flow of blood through these tissues is quite poor in the setting of compromised myocardial contractility the acids sit in the tissues.  The blood that is therefore sitting in the cord at the time of sampling actually represents blood that was sent to the placenta “when times were good”.  When the baby is delivered and we do our job of resuscitating the circulation that is restored then drives the lactic acid into the blood stream and consumes the buffering HCO3 leading to the more typical gases we are accustomed to seeing and reestablishing the congruence our brains so desire.  This in fact forms the basis for most HIE protocols which includes a requirement of a cord gas OR arterial blood gas in the first hour of life with a pH < 7.00.

Acidosis May Be Good For the Fetus

To bend your mind just a little further, animal evidence suggests that those fetuses who develop acidosis may benefit from the same and be at an advantage over those infants who don’t get acidemia.  Laptook AR et al published Effects of lactic acid infusions and pH on cerebral blood flow and metabolism.  In this study of piglets, infusion of lactic acid improved cerebral blood flow.  I would suggest improvement in cerebral blood flow of the stressed fetus would be a good thing.  Additionally we know that lactate may be used by the fetus as additional metabolic fuel for the brain which under stress would be another benefit.  Finally the acidemic fetus is able to offload O2 to the tissues via the Bohr effect.  In case you have forgotten this phenomenon, it is the tendency for oxygen to more readily sever its tie to hemoglobin and move into the tissues.

I hope you have found this as interesting as I have in writing it.  The next time you see a good cord gas in a depressed infant, pause for a few seconds and ask yourself is this really a good or a bad thing?

 

Kangaroo Care and Sleep

Kangaroo Care and Sleep

By Diane Schultz

A Mother’s arms are full of tenderness and children sleep soundly in them – Victor Hugo

The NICU is a loud and chaotic place, that can be painful to be in at times. Its hard to get a good nights sleep (especially for the nurses!). When you think about how much our infants are handled and disturbed, poked and prodded, all in almost continual daylight, it’s a wonder they get any sleep.

For normal neurodevelopment the infant needs both active and quiet sleep. Sleep in an infant is divided into REM (active sleep) and NON-REM (quiet sleep). During quiet sleep you see very little movement and a regular breathing pattern, whereas active sleep involves movement with an irregular breathing pattern.

The importance of Quiet Sleep:

• Without it, the infant doesn’t get enough active sleep.
• Provides the infant with a break from the busy NICU environment.
• Lessons the release of glucocorticoids (Increased cortisol can cause neuronal cell death).
• Restorative.
• Necessary for brain development.
• Increased quiet sleep = decreased risk of SIDS.

The importance of Active Sleep:

• Active sleep promotes brain maturation (US DHHS, 2003; Mirmiran, 1995).
• Most memory consolidation and learning occurs in this state (Smith, 2003).
• Nerve cell connections are restructured (synaptic plasticity) (Marks et al., 1995).

Due to the NICU environment, the infant ends up having slower sleep organization maturation and with increased cortisol they are more apt to have a disturbed and less restful sleep.

A complete cycle of sleep includes moving from active sleep to quiet sleep and back to active sleep. Full term and preterms >32 weeks postconceptional age will need about 60-70 minutes for a cycle. Infants <32 weeks postconceptional age will need about 90 minutes. So when infants come out for KC, we try to plan for at least that amount of time.

You will see when infants are placed in KC, the infant settles and goes into a deep sleep. To accommodate this, you will need comfortable chairs for the parent and good support for their arms. You also want to make sure they have had something to eat or drink, pumped breast milk, used the washroom and had something for pain if needed. Don’t be surprised if your parent falls asleep as well; oxytocin will end up kicking in (the cuddle hormone) and they often find it hard to stay awake. We also provide warmed blankets for our parents to encourage everyone to get comfortable and rest. Snoring is a common side effect of KC in our unit…

While in KC, the infants have a deep sleep with less arousal and better sleep organization than when not in KC (Ludington-Hoe et al., 2006)

In Scher et al.’s study (2009) they found that infants’ brain maturation was accelerated and brain complexity increased with 1.5 hours of KC/day for 4 days/wk from 32-40wks pma. Enhanced development in five sensory areas of the brain was shown with KC that was not seen in infants who did not get KC (both preterm and full term).

With all the evidence pointing to KC being beneficial for a good night’s sleep, I find it difficult to understand why so many are skeptical of it!

Sleep is that golden chain that ties health and our bodies together – Thomas Dekker