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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.
Caffeine seems to be good for preterm infants. We know that it reduces the frequency of apnea in the this population and moreover facilitates weaning off the ventilator in a shorter time frame than if one never received it at all. The earlier you give it also seems to make a difference as shown in the Cochrane review on prophylactic caffeine. When given in such a fashion the chances of successful extubation increase. Less time on the ventilator not surprisingly leads to less chronic lung disease which is also a good thing. I have written about caffeine more than once though so why is this post different? The question now seems to be how much caffeine is enough to get the best outcomes for our infants. Last month I wrote about the fact that as the half life of caffeine in the growing preterm infant shortens, our strategy in the NICU might be to change the dosing of caffeine as the patient ages. Some time ago though I wrote about the use of higher doses of caffeine and in the study analyzed warned that there had been a finding of increased cerebellar hemorrhage in the group randomized to receive the higher dosing. I don’t know about where you work but we are starting to see a trend towards using higher caffeine base dosing above 5 mg/kg/d. Essentially, we are at times “titrating to effect” with dosing being as high as 8-10 mg/kg/d of caffeine base. Does it work to improve meaningful outcomes? This month Vliegenthart R et al published a systematic review of all RCTs that compared a high vs low dosing strategy for caffeine in infants under 32 weeks at birth; High versus standard dose caffeine for apnoea: a systematic review. All told there were 6 studies that met the criteria for inclusion. Low dosing (all in caffeine base) was considered to be 5- 15 mg/kg with a maintenance dose of 2.5 mg/kg to 5 mg/kg. High dosing was a load of 5 mg/kg to 40 mg/kg with a maintenance of 2.5 mg/kg to 15 mg/kg. The variability in the dosing (some of which I would not consider high at all) makes the quality of the included studies questionable so a word of warning that the results may not truly be “high” vs “low” but rather “inconsistently high” vs. “inconsistently low”. The results though may show some interesting findings that I think provide some reassurance that higher dosing can allow us to sleep at night. On the positive front, while there was no benefit to BPD and mortality at 36 weeks PMA they did find if they looked only at those babies who were treated with caffeine greater than 14 days there was a statistically significant difference in both reduction of BPD and decreased risk of BPD and mortality. This makes quite a bit of sense if you think about it for a moment. If we know that caffeine improves the chances of successful extubation and we also know it reduces apnea, then who might be on caffeine for less than 2 weeks? The most stable of babies I would expect! These babies were all < 32 weeks at birth. What the review suggests is that those babies who needed caffeine for longer durations benefit the most from the higher dose. I think I can buy that. On the adverse event side, I suppose it shouldn’t surprise many that the risk of tachycardia was statistically increased with an RR of 3.4. Anyone who has explored higher dosing would certainly buy that as a side effect that we probably didn’t need an RCT to prove to us. Never mind that, have you ever taken your own pulse after a couple strong coffees in the morning? What did it not show? It’s what the study didn’t show that is almost equally interesting. The cerebellar hemorrhages seen in the study I previously wrote about were not seen at all in the other studies. There could be a lesson in there about taking too much stock in secondary outcomes in small studies… Also of note, looking at longer term outcome measures there appears to be no evidence of harm when the patients are all pooled together. The total number of patients in all of these studies was 620 which for a neonatal systematic review is not bad. A larger RCT may be needed to conclusively tell us what to do with a high and low dosing strategy that we can all agree on. What do we do though in the here and now? More specifically, if you are on call tomorrow and a baby is on 5 mg/kg/d of caffeine already, will you intubate them if they are having copious apneic events or give them a higher dose of caffeine when CPAP or NIPPV that they are already on isn’t cutting it? That is where the truth about how you feel about the evidence really comes out. These decisions are never easy but unfortunately you sometimes have to make a decision and the perfect study hasn’t been done yet. I am not sure where you sit on this but I think this study while certainly flawed gives me some comfort that nothing is truly standing out especially given the fact that some of the “high dose” studies were truly high. Will see what happens with my next patient!
Given that many preterm infants as they near term equivalent age are ready to go home it is common practice to discontinue caffeine sometime between 33-34 weeks PMA. We do this as we try to time the readiness for discharge in terms of feeding, to the desire to see how infants fare off caffeine. In general, most units I believe try to send babies home without caffeine so we do our best to judge the right timing in stopping this medication. After a period of 5-7 days we generally declare the infant safe to be off caffeine and then move on to other issues preventing them from going home to their families. This strategy generally works well for those infants who are born at later gestations but as Rhein LM et al demonstrated in their paper Effects of caffeine on intermittent hypoxia in infants born prematurely: a randomized clinical trial., after caffeine is stopped, the number of intermittent hypoxic (IH) events are not trivial between 35-39 weeks. Caffeine it would seem may still offer some benefit to those infants who seem otherwise ready to discontinue the medication. What the authors noted in this randomized controlled trial was that the difference caffeine made when continued past 34 weeks was limited to reducing these IH events only from 35-36 weeks but the effect didn’t last past that. Why might that have been? Well it could be that the babies after 36 weeks don’t have enough events to really show a difference or it could be that the dose of caffeine isn’t enough by that point. The latter may well be the case as the metabolism of caffeine ramps up during later gestations and changes from a half life greater than a day in the smallest infants to many hours closer to term. Maybe the caffeine just clears faster? Follow-up Study attempts to answer that very question. Recognizing the possibility that levels of caffeine were falling too low after 36 weeks the authors of the previous study begun anew to ask the same question but this time looking at caffeine levels in saliva to ensure that sufficient levels were obtained to demonstrate a difference in the outcome of frequency of IH. In this study, they compared the original cohort of patients who did not receive caffeine after planned discontinuation (N=53) to 27 infants who were randomized to one of two caffeine treatments once the decision to stop caffeine was made. Until 36 weeks PMA each patient was given a standard 10 mg/kg of caffeine case and then randomized to two different strategies. The two dosing strategies were 14 mg/kg of caffeine citrate (equals 7 mg/kg of caffeine base) vs 20 mg/kg (10 mg/kg caffeine base) which both started once the patient reached 36 weeks in anticipation of increased clearance. Salivary caffeine levels were measured just prior to stopping the usual dose of caffeine and then one week after starting 10 mg/kg dosing and then at 37 and 38 weeks respectively on the higher dosing. Adequate serum levels are understood to be > 20 mcg/ml and salivary and plasma concentrations have been shown to have a high level of agreement previously so salivary measurement seems like a good approach. Given that it was a small study it is work noting that the average age of the group that did not receive caffeine was 29.1 weeks compared to the caffeine groups at 27.9 weeks. This becomes important in the context of the results in that earlier gestational age patients would be expected to have more apnea which is not what was observed suggesting a beneficial effect of caffeine even at this later gestational age. Each patient was to be monitored with an oximeter until 40 weeks as per unit guidelines. So does caffeine make a difference once term gestation is reached? A total of 32 infants were enrolled with 12 infants receiving the 14 mg/kg and 14 the 20 mg/kg dosing. All infants irrespective of assigned group had caffeine concentrations above 20 mcg/mL ensuring that a therapeutic dose had been received. The intent had been to look at babies out to 40 weeks with pulse oximetry even when discharged but owing to drop off in compliance with monitoring for a minimum of 10 hours per PMA week the analysis was restricted to infants at 37 and 38 weeks which still meant extension past 36 weeks as had been looked at already in the previous study. The design of this study then compared infants receiving known therapeutic dosing at this GA range with a previous cohort from the last study that did not receive caffeine after clinicians had determined it was no longer needed. The outcomes here were measured in seconds per 24 hours of intermittent hypoxia (An IH event was defined as a decrease in SaO2 by ⩾ 10% from baseline and lasting for ⩾5 s). For graphical purposes the authors chose to display the number of seconds oxygen saturation fell below 90% per day and grouped the two caffeine patients together given that the salivary levels in both were therapeutic. As shown a significant difference in events was seen at all gestational ages. Putting it into context The scale used I find interesting and I can’t help but wonder if it was done intentionally to provide impact. The outcome here is measured in seconds and when you are speaking about a mean of 1200 vs 600 seconds it sounds very dramatic but changing that into minutes you are talking about 20 vs 10 minutes a day. Even allowing for the interquartile ranges it really is not more than 50 minutes of saturation less than 90% at 36 weeks. The difference of course as you increase in gestation becomes less as well. When looking at the amount of time spent under 80% for the groups at the three different gestational ages there is still a difference but the amount of time at 36, 27 and 38 weeks was 229, 118 and 84 seconds respectively without caffeine (about 4, 2 and 1 minute per day respectively) vs 83, 41, and 22 seconds in the caffeine groups. I can’t help but think this is a case of statistical significance with questionable clinical significance. The authors don’t indicate that any patients were readmitted with “blue spells” who were being monitored at home which then leaves the sole question in my mind being “Do these brief periods of hypoxemia matter?” In the absence of a long-term follow-up study I would have to say I don’t know but while I have always been a fan of caffeine I am just not sure. Should we be in a rush to stop caffeine? Well, given that the long term results of the CAP study suggest the drug is safe in the preterm population I would suggest there is no reason to be concerned about continuing caffeine a little longer. If the goal is getting patients home and discharging on caffeine is something you are comfortable with then continuing past 35 weeks is something that may have clinical impact. At the very least I remain comfortable in my own practice of not being in a rush to stop this medication and on occasion sending a patient home with it as well.
Caffeine has been used for over 30 years to treat episodes of apnea in preterm infants. Caffeine citrate is considered one of the most safety and effective drugs, with few or no side effects, used in our Neonatal Intensive Care Units (NICU). Many randomized studies describe the use and benefits of caffeine in the preterm population. Studies based on caffeine prophylactic use in preterm infants, as well as new indications out of apnea of prematurity have been recently published. Despite being one of the drugs most used in our NICU, are not yet available clinical practice guidelines and / or protocols in many of our NICU. Therefore, I invite you to participate in a study to determine the use of caffeine and its indications in NICUs around the world through the following survey. Once analyzed all the surveys, I promise to send you the results. Those you are interested you can send me your email adress and I will send you the survey. Dr. Laura Castells Vilella firstname.lastname@example.org Neonatologist and NICU’s Manager IDC Salud Hospital General de Catalunya (Barcelona, Spain)