Neonatal Intensive Care Monitoring

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Neonatal Intensive Care Monitoring

• Overview
• Neonatal Blood Gases
• Pulse Oximeters
• Neonatal Hemodynamic Equipment
• Transcutaneous Monitors

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Neonatal Blood Gases - Sampling Possibilities

• Arterial Gases
• Venous Gases
• Capillary

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Arterial Gases

• Radial, Brachial, Temporal Punctures
• Radial Artery Line
• Umbilical Artery Gases
• Umbilical Artery Catheter (UAC)
• Preductal placement vs postductal placement

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Venous Gases

• Drawn from Umbilical Venous Catheter (UVC)
• Not desirable but......

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Capillary Gases

• Drawn from heel
• Procedure
• heel warmed to arterialize blood
• lancet puncture
• blood flows, trapped in capillary tube

Preferred Sites
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Variability in Cap Gases

• Warming time
• Amount of contact with air
• Squeezing blood
• As a result, not desired but .......

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Comparative
pH pCO2 HCO3 PO2 Arterial 7.4 40 24 60-80 (term)
Arterial 7.4 40 24 50-70 (preterm) Capillary 7
.4 40 24 40-50 Venous 7.35 45 24 35-45
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Pulse Oximeters

• Sites of attachment
• (foot and hand)
• Preductal placement in first twelve hours
• (right hand)

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Pulse Oximeters

• Reads high
• Methemoglobin
• Caboxyhemoglobin
• Jaundice
• Reads low
• Medical dyes
• Other causes of inaccuracy
• Motion
• Hypothermia/vasoconstriction
• Hypotension
• Excessive ambient light on sensor probe

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Hemodynamic Monitoring

• Umbilical Artery Catheter (UAC) preferred

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UAC Insertion Procedure

• Insertional position 1/3 length heel to crown
• Procedure
• sterile field and drape
• purse string suture around umbilicus
• cut cord and snug
• tease umbilical artery open
• insert catheter
• fix position
• follow with CXR

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Monitoring UAC Post Insertion

• Position of catheter tip
• (aortic arch is preductal and not preferred)
  Normal position above diaphragm
• (low position is L3-L4)
• Monitor leg color of infant
• (blanching indicates obstruction of flow)

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Indwelling UAC Gases

• Orange Medical Company
• PO2 electrode at tip of catheter
• Provides continuous reading

Cathode
Anode
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Transcutaneous Gas Monitors

• Useful as trend monitor
• Can detect hypoxemia, hyperoxemia
• Can detect hypocarbia, hypercarbia
• Also responds to changes in blood flow

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Types of Transcutaneous Monitors

• Single Electrode Models
• PO2 most common

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Types of Transcutaneous Monitors

• Dual element electrodes
• PO2 and PCO2
• Called TcPO2 and TcPCO2

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Principle of Operation Tc Monitors

• Heated electrode placed on skin
• Temperature 43 to 45 C
• Arterializes sample
• Gas diffuses through skin

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Calibration of Transcutaneous Monitors

• Requires high and low calibration
• TcPO2
• Can be done with chemical zero and room air
• Most commonly done with cylinders

Calibration value Concentration of gas in
cylinder x Pb
Using a cylinder that contains 10 O2, what would
be the calibration value of a TcPO2 device if the
barometric pressure was 760?
Calibration value .1 x 760 76 mm Hg
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Calibration of TcPCO2 Devices

• Similar to TcPO2 except.......
• 1.6 is the factor that accounts for heating
  increasing CO2 production

Calibration value Concentration of CO2 x Pb
1 .6
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Normal Transcutaneous Gases

• TcPCO2 is 35 to 45 torr
• TcPO2 is 50 to 70 torr

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Advantages of Transcutaneous Monitors

• Decreased number of sticks
• cost reduction
• lower infant risk (less invasive)
• Trend tool
• blood sample provides view at one moment
• gases values wander ( 7 torr)
• infant reaction to sample varies

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Problems with Transcutaneous Monitors

• Labor Intensive
• Change site every 4 to 6 hours or more
• Limited choices for attachment
• (site must have perfusion)
• Air leak around electrode
• Burns
• called hookies after Huch

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Interpretation of Tc Results

• Air leak under electrode
• TcPCO2 reading near zero
• TcPO2 reading near PbO2
• Decreased perfusion under electrode
• TcPCO2 will increase
• TcPO2 will decrease