Neonatal Intensive Care Monitoring

1. Neonatal Intensive Care Monitoring • Overview • Neonatal Blood Gases • Pulse Oximeters • Neonatal Hemodynamic Equipment • Transcutaneous Monitors

2. Neonatal Blood Gases - Sampling Possibilities • Arterial Gases • Venous Gases • Capillary

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

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

5. Capillary Gases • Drawn from heel • Procedure: • heel warmed to ‘arterialize’ blood • lancet puncture • blood flows, trapped in capillary tube Preferred Sites

6. Variability in Cap Gases • Warming time • Amount of contact with air • Squeezing blood • As a result, not desired but .......

7. 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

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

9. 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

10. Hemodynamic Monitoring • Umbilical Artery Catheter (UAC) preferred

11. 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

12. 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)

13. Indwelling UAC Gases • Orange Medical Company • PO2 electrode at tip of catheter • Provides continuous reading Cathode Anode

14. Transcutaneous Gas Monitors • Useful as ‘trend’ monitor • Can detect hypoxemia, hyperoxemia • Can detect hypocarbia, hypercarbia • Also responds to changes in blood flow

15. Types of Transcutaneous Monitors • Single Electrode Models • PO2 most common

16. Types of Transcutaneous Monitors • Dual element electrodes • PO2 and PCO2 • Called TcPO2 and TcPCO2

17. Principle of Operation Tc Monitors • Heated electrode placed on skin • Temperature 43 to 45 C • ‘Arterializes’ sample • Gas diffuses through skin

18. 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

19. Calibration value = .1 x 760 = 76 = 47.5 1 .6 1 .6 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

20. Normal Transcutaneous Gases • TcPCO2 is 35 to 45 torr • TcPO2 is 50 to 70 torr

21. 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

22. 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

23. 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