Newborn: Apgar Score and Low-Birth Weight

by Thad Wilson, PhD

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    00:00 The Apgar Score. For the newborn, this is one of the more important scales that will be developed.

    00:08 It will be tested on every newborn. It's done a minute after birth and then 5 minutes thereafter.

    00:17 We are looking for 5 primary things: the appearance, pulse, grimace, activity and finally respiration.

    00:30 I'll give you 1 caveat though here about the Apgar score. If an infant needs to be ventilated or they may be put on a positive pressure ventilator, they may not wait for this 1 minute to occur if that breath first breath hasn't been taken but this is a nice way to monitor the various progressions that will occur. So let's take a look at what each of these particular scores mean and how you evaluate them. The scoring system is really quite simple.

    01:02 You're going to take a parameter like activity, you're going to then give it an indicator is the type, you're going to give it either a 0, a 1 or 2 points. So let's go through activity to get a good look at this. Activity, a 0 points would be a limp response, 1 point is flexed arms and legs and then 2 points is active. For the pulse: 0 points is an absence of a pulse, 1 point is below 100 and 2 points is above 100. This grimace or sometimes referred to as reflex irritability either is absent if for 0 points, you have a minimal response or you have a large loud response.

    01:54 Appearance; 0 points is blue or pallor which is pale, 1 point is pink or sometimes a little bit of a blue extremity and then for 2 points completely pink. Finally for respirations: a 0 is absent meaning there are no respirations, 1 point is slow and irregular and finally 2 points is a vigorous cry.

    02:24 Why are you looking for a cry? Because you don't, it's very difficult to look at an infant breathing but you know if they're crying they're breathing out alright. How do you assess this? Looking at the scoring if you have above 7 that's considered good, 4-6 that needs to be assessed again and finally if it's below 4 this is some time that is very serious and more progressive action is needed but again if the infant is not breathing, he does not have a pulse you would definitely have to try to put them on to a ventilator and try other more serious means of trying to get the infant's life back together. How do you further assess the Apgar score other than simply the numbers? Well, the big thing to think about if you have a score less than 7 you need to reassess this particular score every 5 minutes for at least the first 20 minutes of life. You're one thing to get greater than a 7. Interestingly, that first Apgar score at 1 minute does not seem to be very related to outcomes, which is a little bit frustrating because you would think that that would be a very good predictor. Right? What is a good predictor? Is the score between 1 and 5 that is a good measure of if you're able to get vital functions back and then especially the 5-minute score. This is very much associated with increased infant mortality for both pre-term and full-term infant.

    04:05 How do we classify an infant that is pre-term or has a low birth weight? The different ways we do this is via the weight in grams. So if they're less than 2500 g they're considered low birth weight, 1500 g is very low birth weight and less than 1000 g is extremely low birth weight.

    04:31 This is an important process to have in mind and a classification scheme because there are different interventions based upon if the newborn needs, has a low birth weight versus extremely low birth weight. What some of the different developmental functions they will be able to do and what the treatment interventions that you want to employ? So what would cause low birth weight? Low birth weight is usually caused by one of 2 things. One is prematurity, i.e. they were born before they reached full maturity. Another one is if there is any reason why there is growth restriction. So intrauterine growth restriction is another way that though you don't get as high a birth weight because the infant can't grow anymore because of anatomical structures associated with mom.

    05:23 What are the risks? Sudden infant death syndrome is high in low birth weight, so is overall mortality.

    05:33 So specific mortality as well is related to sudden infant death. Now what are some of the problems associated with low birth weight babies and problems with babies trying to interact with the environment and themselves? Well, these could be things like impaired thermoregulation. An infant doesn't have a great ability to regulate its own body temperature, it's immune function is low, they usually have hypoglycemia which is low blood sugar, polycystemia which is high hematocrit or high red blood cells per unit volume and there oftentimes is impairments in neurocognitivity as well as emotional development. So what makes for low blood glucose levels? Well in the newborn, hepatic glycogen stores are low. There is also a stress response that has just happened and that stress response is huge. Hypoxia, hypothermia and hypoglycemia all occurring at once during birth because in this birth process you needed to breathe for the first time. What made you want to start to breathe? That hypoxia. You're cold, you just left the mother's womb, you're now outside in an environment in which you're radiating up heat, you might still be wet as well as having low blood glucose. All of these stimulate a fight or flight response and increases in epinephrine.

    07:07 This stimulates glycogenolysis and gluconeogenesis as well as fat stores and this will try to increase the amount of energy available but one of the primary things it does is allow for more ketone bodies to be formed to be able to use as energy sources. So again, it's a very challenging environment for the newborn and one of the reasons is because of this hypoglycemia.

    About the Lecture

    The lecture Newborn: Apgar Score and Low-Birth Weight by Thad Wilson, PhD is from the course Human Development.

    Included Quiz Questions

    1. 8
    2. 6
    3. 4
    4. 2
    1. Ketone bodies
    2. Glucose
    3. Oxygen
    4. Insulin

    Author of lecture Newborn: Apgar Score and Low-Birth Weight

     Thad Wilson, PhD

    Thad Wilson, PhD

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