Neonatal Intensive Care Monitoring nOverview –Neonatal Blood Gases –Pulse Oximeters –Neonatal Hemodynamic Equipment –Transcutaneous Monitors

Neonatal Blood Gases - Sampling Possibilities nArterial Gases nVenous Gases nCapillary

Arterial Gases nRadial, Brachial, Temporal Punctures nRadial Artery Line nUmbilical Artery Gases nUmbilical Artery Catheter (UAC) nPreductal placement vs postductal placement

Venous Gases nDrawn from Umbilical Venous Catheter (UVC) nNot desirable but......

Capillary Gases nDrawn from heel nProcedure: –heel warmed to ‘arterialize’ blood –lancet puncture –blood flows, trapped in capillary tube Preferred Sites

Variability in Cap Gases nWarming time nAmount of contact with air nSqueezing blood nAs a result, not desired but

Comparative pHpCO2HCO3PO2 Arterial (term) Arterial (preterm) Capillary Venous

Pulse Oximeters nSites of attachment (foot and hand) nPreductal placement in first twelve hours (right hand)

Pulse Oximeters nReads high –Methemoglobin –Caboxyhemoglobin –Jaundice nReads low –Medical dyes nOther causes of inaccuracy –Motion –Hypothermia/vasoconstriction –Hypotension –Excessive ambient light on sensor probe

Hemodynamic Monitoring nUmbilical Artery Catheter (UAC) preferred

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

Monitoring UAC Post Insertion nPosition of catheter tip (aortic arch is preductal and not preferred) Normal position above diaphragm (low position is L3-L4) nMonitor leg color of infant (blanching indicates obstruction of flow)

Indwelling UAC Gases nOrange Medical Company nPO2 electrode at tip of catheter nProvides continuous reading Cathode Anode

Transcutaneous Gas Monitors nUseful as ‘trend’ monitor nCan detect hypoxemia, hyperoxemia nCan detect hypocarbia, hypercarbia nAlso responds to changes in blood flow

Types of Transcutaneous Monitors n Single Electrode Models nPO2 most common

Types of Transcutaneous Monitors nDual element electrodes nPO2 and PCO2 nCalled TcPO2 and TcPCO2

Principle of Operation Tc Monitors nHeated electrode placed on skin nTemperature 43 to 45 C n‘Arterializes’ sample nGas diffuses through skin

Calibration of Transcutaneous Monitors nRequires high and low calibration nTcPO2 –Can be done with chemical zero and room air –Most commonly done with cylinders Calibration value = Concentration of gas in cylinder x Pb Calibration value =.1 x 760 = 76 mm Hg Using a cylinder that contains 10% O2, what would be the calibration value of a TcPO2 device if the barometric pressure was 760?

Calibration of TcPCO2 Devices nSimilar to TcPO2 except n1.6 is the factor that accounts for heating increasing CO2 production Calibration value = Concentration of CO2 x Pb 1.6 Calibration value =.1 x 760 = 76 =

Normal Transcutaneous Gases nTcPCO2 is 35 to 45 torr nTcPO2 is 50 to 70 torr

Advantages of Transcutaneous Monitors nDecreased number of ‘sticks’ –cost reduction –lower infant risk (less invasive) nTrend tool –blood sample provides ‘view’ at one moment –gases values wander (+ 7 torr) –infant reaction to sample varies

Problems with Transcutaneous Monitors nLabor Intensive –Change site every 4 to 6 hours or more –Limited choices for attachment –(site must have perfusion) –Air leak around electrode nBurns –called ‘hookies’ after Huch

Interpretation of Tc Results nAir leak under electrode –TcPCO2 reading near zero –TcPO2 reading near PbO2 nDecreased perfusion under electrode –TcPCO2 will increase –TcPO2 will decrease