I consireder the signs and symptoms of low cardiac output the most important determinant of therapy. I prefer start dopamine. An exact number of blood pressure to indicate start vasoactive drugs I think dangerous.

Dear Jose

I can say you that on the book "Surgery for Congenital heart defects" Stark - de Leval Saunders II edition - for the newborns with weight ranging from 2 to 3 Kgs the "mean" normal pressure ranges from 25-to 35 mmHg. At this level all the organs are well perfused on cardio-pulmonary by-pass

Sincerely

Thank you Dario. I agree with yo. Stark suggested the "MEAN" blod pressure ranging from 25 to 35 with well perfused organs. There is no mention to mean pressure in the question. I consider if low cardiac outout signs are present there is no necessary the pressure decrease below 30 mmH to start vasoative therapy.

I agree with you, for 2 to 3 Kg children, but I am asking about premature children that weight less than 1500g, These children have problems with cerebral flow autoregulation, specially in the first 24 to 48h of life, and some authors suggest hypotension can lead to cerebral damage in them. But the limits to normal mean blood pressure in these children is not clear. And besides, the best initial therapy is not determined, which inotrope is better in your oppinion?

Dear Fatima. Excuse me. I wrong in answer your question. The newborn that you treat is a very difficult condition in medicicine. I don't have experience with premature children that weight less than 1500g. I have colleagues that work only in this area. I will ask for them.

You have asked a million dollar question which we neonatologist all would like to have the answer. UK uses gestational week as the reasonable mean BP for VLBW in the first week of life. But, scientific evidence is not available. Several groups reported normal ranges in the first several days of life but if you look into the S.D. then BP as low as single digit can be normal as defined by statistics. Regardless what number you go by the use of inotropic agent is associated with higher incidence of IVH excpect we do not know which one is the cause of IVH. Hypotension itself or inotropic agent? Oliguria is a bad parameter since within the first 24 hours it can be as low as 0.5 ml/kg/hr but still normal (term infant can be normal without any urine in the first 24 hours). Metabolic acidosis is a bad parameter since most VLBW can have low bicarbonate level due to immature tubular function. Capillary refill is one of the worst indicator. So, the bottomline is we do not know how to define hypotension in VLBW in the first several days of life. Dopamine low dose can improve urine output so some neo use it. Dobutamine is commonly used but physiologically may not be reasonable depends on which textbook you believe. Epinephrine is a new trend in my unit but simply increase afterload may not be good for tissue perfusion. Epinephrine increases BP by vasoconstriction but not tissue perfusion. Vasspressin can be used when you are desperate. At the end, I am not suggesting you how to treat hypotension in VLBW but to tell you there is no agreement about acceptable BP for VLBW. Good luck. Please tell me the answer when you figure out this practical issue.

Thank you for your answer Dr. Teng, in fact, as this question is not easy to answer, I wanted to know the experience of other colleagues. I believe that untill this moment, literature doesn't give an answer to this question. In our unity people try to use gestational age, and I think it is a good parameter, but some of our neonatologists get very unconfortable when mean arterial pressure falls under 30mmHg. And besides, it is not a question of a magic number (30 mmHg or Gestational Age), in fact, the most difficult is to realize what is normal and abnormal in transitional circulation. And mostly, how to protect the VLBW from IVH, as cerebral flow autoregulation is abnormal in these neonates. Thank you

I agree with you Fatima. It all depend upon what you believe and whether you feel comfortable with the number or not. I am a little bit prone to avoid uing inotropic agent recently. One of the ELBW had very low MBP for several hours after birth but all other numbers were fine with low vent support. The blood pressure improved overnight with IVH. I did not sleep too well that night in fact. But, I really do not know what is the best way to manage it. By the way, to use GA in weeks as cut-off for MBP came from British group as a concensus without solid evidence. A lot of us use it simply because it is easy to use. I guess prematurity itself is abnormal so there is no normal range BP for it.

Recently we use NIRS brain saturation monitor to establish the perfusion of brain during anesthesia and. If there is no change in brain tissue oxygen saturation we accept low pressures, but if there is a change we try to normalize brain saturation with some interventionsa ( pCO2., inotropes etc., transfusion). We try to mesure also splanchnicus saturation with the NIRS.

It is a very interesting idea! Unfortunately we don't have NIRS in our ICU, but it is something to think about, thank you.

In our experience NIRS very promptly reflects changes in cerebral flow in cardiac surgery in children as you can see with the institution of CPB or weaning from CPB or some accident with x clamps where the NIRS was the only monitor signaling a problem. We also accept higher values of pCO2 as the NIRS curve trend is very similar to trends in PaCO2. In my opinion NIRS is measuring very easily what we always wanted to have - tissue saturation. I don't have the experience with the use NIRS in the ICU.

as I said, we don't have NIRS in our ICU, but it could be interesting to use it. Thank you for your comment

There is no literature to my knowledge to show increase BP is associated with improved CBF. Just reviewed the topic with my fellows last Thursday and it was kind of frustrating that no good criteria to define hypotension and our knowledge of inotropes is extrapolated from animal or older patients. No to say no data showed that treatment of hypotension actually improved long term outcome. However, I did identify a few papers found association between hupotension treatment and worse neurological outcome. May be there is really no "physiological data" for premature infants since they are not really "physiological" since they are born prematurely.

yes, I do agree with you! It is very frustrating that there are no good criteria to hypotension in very low birth weight infants. And sometimes people get very anxious with the values of blood pressure in a apparently stable infant. And some want to begin dobutamine, others dopamine. But I didn't find a good work to support any drugs in an infant with low blood pressure and normal echocardiogram. Sometimes I would like only to wait, but it is very difficult if mean blood pressure falls bellow 30mmHg.

I did wait for a few hours on several premature infants when saturation is fine and FiO2 was steadily decreasing even MBP was lower than 25 mm-Hg. I was scary and some of my colleagues questioned me about the decision. At least there was no IVH and those micropremies went home successfully. People may say there is no evidence that tolerating low BP is fine, but, there is also no evidence to support treatment improves the outcome.

Yes, I do agree with you, but unfortunatelly I am just the cardiologist... I can give them my oppinion, but the final decision of begining or not drugs is out of my hands. As I began by the end of last year to work with this group, I have been thinking about doing some protocol to drugs, but the problem is always the same... there is no evidence to support treatment or tolerating low BP. May be an observational study of our patients could be fine to decide abt treating or not,

So, unfortunately I am a neonatologist and also have no clue about how to manage the issue. Just stick to what you believe in. Best.

Thanx! As soon as I have data I will tell you... may be we will confirm our impression...

Blood pressure Is the result of complex interaction between ventricular ejection and arterial tree. It is best described as a wave of pressure propagation and can differ in value depending of the site of measurement and the ttechnique of monitoring. We are most concerned by organ perfusion (especially the brain) than the absolute pressure of perfusion. NIRS (cerebral, mesenteric and renal) is an InterestIng approach in my experience when it is coupled with transcranial Doppler, mesenteric Doppler and renal Doppler- at least in term and near term babies.

in dealing with neonatal with low cardiac output, I try to obtain a transcranial Doppler with good and consistent diastolic flow (IP < 1, 2). with a visible diastolic flow in renal Doppler and an IP < 1·2 for mesenteric Doppler. in the majority of case, we obtain that with a mean blood pressure of 50-55mmHg (invasive radial artery).

The limit of this is the presence of a large ductus arteriosus with cerebral diastolic stealthat can alter the cerebral Doppler. (I am dealing now with such a case.) In this case, I think (and perhaps I am wrong,) that a good NIRS is a useful indication of correct cerebral perfusion. But I now that in the renal bed, we can have a good NIRS in situations were the renal flow is low. So, how to interpret a good cerebral NIRS?

I have a very small experience with tiny preterm babies. It seem logical to me that bad cerebral Doppler or low NIRS reading must trigger efforts to augment cardiac output and blood pressure.

For term and near term babies a 50-55mmHg mean pressure is not hard to find. My question is that in very low birth weight infants usually there is a large DA, and mean blood pressure many times is less than 30mmHg, and intensive care team gets nervous with that. Evaluation of cerebral perfusion is of great value for these newborns, but no excelent non invasive parameter is available. I have no experience with NIRS, but it may be a god alternative. Thank you for your answer.

My experience with small preterm babies is limited. In the setting of low blood pressure and pda, perhaps the correct attitude is to give indomethacine or paracetamol ibuprofen and use permissive hypercapmia and SaO2 in the low 90 to limit pulmonary blood flow trough the ductus and redirect the ejection of the left ventricular to systemic circulation.

I am in charge of nearly 20 premature babies a year and I find often significant pda in the first noirs after birth.

There's no proven benefit of pda closure with drugs in the first few days of life, even in the very premature you can have spontaneous closure, and avoid the side effects of drugs (that can happen). And for me the most critical moment of blood pressure measurement doubts is in the first 24 to 48h of life, for diuresis is not a good parameter for renal perfusion, skin perfusion can be altered without real problems, except adaptation, and echocardiographic data can be influenced by preload and afterload. There are babies that appear very stable, with a very low blood pressue... to treat or not to treat? I think that treating blood pressure alone is not the best option, but I am the cardiologist of the ICU, and many times I find the babies using dopamine or dobutamine, only to raise blood pressure. For me it is the most difficult moment. Many times echo shows normal function, respiratory needs are fine and when you cut the drug mean blood pressure falls bell ow 30mmHg or even bellow gestational age, but the baby appears fine... begin drugs again? Let the pressure low? What is low blood pressure to a 450g baby? I couldn't find a good answer in any article...

I agree completely with you, based on the articles I have read. Once again, my experience is limited. Indeed, if the baby appears well and perhaps had a good NIRS (or another index of perfusion) it is wise not treat hypotension. But if the pda is significant and index of cerebral perfusion (or systemic perfusion -ph, lactates, dopplers) are not good - and In myexperience, in such a cases, surfactant is ineffective- there is something to add, perhaps inotropes, vasopressors and drugs closing the ducts.

I agree with you, but my only question about ductus arteriosus is that, even if it is large, PDA won't be a problem untill pulmonary resistance falls, and it takes at least 2 or 3 days to happen in very low birth way babies. So I would prefer a more conservative approach to PDA.