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Was adding placement of EKG leads to NRP a good idea after all?

AllThingsNeonatal

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Was adding placement of EKG leads to NRP a good idea after all?

It is hard to believe but it has been almost 3 years since I wrote a piece entitled A 200 year old invention that remains king of all tech in newborn resuscitation. In the post I shared a recent story of a situation in which the EKG leads told a different story that what our ears and fingers would want us to believe. The concept of the piece was that in the setting of pulseless electrical activity (where there is electrical conductance in the myocardium but lack of contraction leaves no blood flow to the body) one could pick up a signal from the EKG leads when there is in fact no pulse or perfusion to vital organs. This single experience led me to postulate that this situation may be more common than we think and the application of EKG leads routinely could lead to errors in decision making during resuscitation of the newborn. It is easy to see how that could occur when you think about the racing pulses of our own in such situations and once chest compressions start one might watch the monitor and forget when they see a heart rate of 70 BPM to check for a corresponding pulse or listen with the stethoscope. I could see for example someone stopping chest compressions and continuing to provide BVM ventilation despite no palpable pulse when they see the QRS complex clearly on the monitor. I didn’t really have much evidence to support this concern but perhaps there is a little more to present now.

A Crafty Animal Study Provides The Evidence

I haven’t presented many animal studies but this one is fairly simple and serves to illustrate the concern in a research model. For those of you who haven’t done animal research, my apologies in advance as you read what happened to this group of piglets. Although it may sound awful, the study has demonstrated that the concern I and others have has is real.

For this study 54 newborn piglets (equivalent to 36-38 weeks GA in humans) were anesthetized and had a flow sensor surgically placed around the carotid artery.  ECG leads were placed as well and then after achieving stabilization, hypoxia was induced with an FiO2 of 0.1 and then asphyxia by disconnecting the ventilator and clamping the ETT.  By having a flow probe around the carotid artery the researchers were able to determine the point of no cardiac output and simultaneously monitor for electrical activity via the EKG leads.  Auscultation for heart sounds was performed as well.

The results essentially confirm why I have been concerned with an over reliance on EKG leads.

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Of the 57 piglets, 14 had asystole and no carotid flow but in 23 there was still a heart rate present on the EKG with no detectable carotid flow. This yields a sensitivity of only 37%.  Moreover, the overall accuracy of the ECG was only 56%.

Meanwhile the stethoscope which I have referred to previously as the “king” in these situations had 100% sensitivity so remains deserving of that title.

What do we do with such information?

I think the results give us reason to pause and remember that faster isn’t always better.  Previous research has shown that signal acquisition with EKG leads is faster than with oximetry.  While a low heart rate detected quickly is helpful to know what the state of the infant is and begin the NRP pathway, we simply can’t rely on the EKG to tell us the whole story.  We work in interdisciplinary teams and need to support one another in resuscitations and provide the team with the necessary information to perform well.  The next time you are in such a situation remember that the EKG is only one part of the story and that auscultation for heart sounds and palpation of the umbilical cord for pulsation are necessary steps to demonstrate conclusively that you don’t just have a rhythm but a perfusing one.

I would like to thank the Edmonton group for continuing to put out such important work in the field of resuscitation!



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I see people in Delivery Rooms more worried about placing leads and getting a decent EKG than listening to the baby and feeling pulses. It is sad when we think "technology" is the answer to everything. Around the NICU nowadays nurses do Vital Signs on the monitors, and forgot how to write true nurses notes that have value, just because we are using technology. It is sad!

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We don't use EKG, we struggle to get the signals from Sat probe , what to talk about EKG leads lifting off the chest. Although one can say that wipe off vernix from chest but even then leads can't stick. 

I think too much research on useless things is sad in evidence based medicine. Make things simple in neonatology and think babies are born not only in developed world but also in poor developing countries with no access to even stethoscopes, what to talk about EKG leads and monitor. At that time one rely only on cord palpating for heart rate. 

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Its importance will come when you will face a baby when you can not hear His Heart sounds like Hydrops babies

I wittnessed chest compression start to one hydrops baby as no hear beat detected by auscultation and after PPV

I am with ECG leads and monitor to be available in perfect setup

Using ECG leads accirding to NRP guidlines should be implemented from january 2017

Tell now we are trying to make it available in OR and LR

How should you assess the baby’s heart rate response during compressions?

Briefly pause compressions and, if necessary, pause ventilation.

An electronic cardiac (ECG) monitor is the preferred method for assessing heart rate during chest compressions. You may assess the baby’s heart rate by listening with a stethoscope or using a pulse oximeter. There are limitations to each of these methods.

•During resuscitation,auscultation can be difficult,prolonging the interruption in compressions and potentially giving inaccurate results.

•If the baby’s perfusion is very poor,a pulse oximeter may not reliably detect the baby’s pulse.

•An electroniccardiac(ECG) monitor displays the heart’s electrical activity and may shorten the interruption in compressions, but slow electrical activity may be present without the heart pumping blood (“pulseless electrical activity”).  In the newborn, pulseless electrical activity is treated the same as an absent pulse (asystole).

Copied from textbook of neonatal resusscitation 7th edition

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I admit with all that old reflexes must not be forgotten but I feel relaxed when letting my residents do the NRP when I am looking to an EKG! EkG is very helpful but from time to time , it would be good not to put it to let the new generation realise that old habits are also good !! 

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One of my OB colleagues had a full-term vaginal delivery that developed shoulder dystocia which somehow had trapped the cord. Despite maneuvers and other efforts, it took several minutes to get the baby delivered. The neonatal team was ready and waiting for the handoff. The infant was limp, not breathing, had no apparent heartbeat and was pulseless without any visible perfusion. After a minute of resuscitation, all findings remained the same except for a faint, slow heartbeat was heard. An emergency Umbilical Vein Catheter was placed and fluid volume was provided. Within seconds heart rate picked up, pulses were palpable, perfusion and color improved. Within minutes breathing resumed and tone and limb movement returned. The infant was treated for a broken humerus and a partial Erb's Palsy but otherwise had no further sequelae. 

It seems to me that when you have an EKG showing heartbeats, this is evidence of cardiac contractions per se, not just pacemaker activity. When this is coupled with no pulses or perfusion, this is a sign of shock. In a newborn with shock, even the pulse oximeter may not register reliably. In severe shock, the heart is contracting but has no volume to deliver to the organs and extremities. Thus, lack of pulse alone cannot, in my opinion, be construed to be the same as asystole, or used to determine when to discontinue resuscitation. Electro-Mechanical Dissociation (EMD), at least in some cases, is nothing more than a heart continuing to beat in the face of significant shock. As it occurred with the infant described above, cord compression can easily flatten and obstruct the umbilical vein (blocking the flow of blood to the infant) while allowing the thick-walled arteries to remain patent (draining blood volume from the infant). Babies that are normovolemic but undergo significant distress can develop acidosis and vasodilation which can also lead to shock.

The animal study cited in the original post found EKG monitoring to be inaccurate and insensitive in terms of a lack of reliable correlation between EKG and carotid blood flow. However, the premise of the study, based upon the belief that an EKG waveform is merely electrical activity, may not always be the case. It is true that in the event of congenital heart disease, cardiomyopathy or cardiac arrhythmia, contractions may be greatly diminished, but EKG waveforms remain an indication of contraction, however weak. Likewise, cessation of waveforms on the EKG tracing is indicative of asystole.

The original poster speculated that EKG waveforms might be unreliable as they do not always correlate with carotid blood flow. He went on to suggest that someone who might persist in resuscitative efforts after a finding of prolonged absent pulses because he's seeing EKG waveforms continue on the monitor might be unwise. However, in cases of severe neonatal shock, cardiac contractions and EKG waveforms may well be ongoing without palpable pulses, audible heart sounds (much of the heartbeat sound is created by the heart muscle contracting against blood that is under systemic pressures flowing through the heart), or pulse oximeter readings (EMD). When this occurs, swift recognition and intervention to restore fluid volume can be life-saving.

I believe the information provided by both the EKG and the physical assessment of heart sounds, pulses, perfusion and obtaining pulse oximetry is essential for optimal resuscitation. In the case of EMD, having electrical assurance of cardiac contractions in the face of absent pulses suggests shock is present allowing for early blood volume replacement in the resuscitative process.

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