Monitoring The Critically Ill Children

長庚兒童醫院 兒童加護科夏紹軒

• The goals and principles of ICU monitoring

• Characteristics of monitoring critically ill children

• Cardiovascular monitoring

• Respiratory monitoring

• Cerebral monitoring

• Conclusions

Principles and Philosophy in Critical

Care Medicine• Early diagnosis and identification of the

problem• Anticipation of possible events and

complications• The holistic approach to a critical illness• The considered use of technology• Primum non nocere• Recognition of the limits of critical care

The goals of monitoring the critically ills (I)

• DO2=CO CaO2=CO (1.34Hb SaO2+0.003PaO2)

• DO2=CBF (1.34Hb SaO2+0.003PaO2)

• PaCO2= （ VCO2×0.863 ） ÷VA

• CO depends on heart rate, preload, myocardium contractility and afterload

• CBFCPP=MAPICP

• Organ functions: CNS, liver, kidney…etc

Balance between demand and supply

• DO2=C.O. CaO2(supply)• VO2C.O. (SaO2-SvO2)(demand)• VO2 經常是一個常數，所以

C.O. 與 (SaO2-SvO2)成反比，同理，CBF與 (SaO2-SjvO2)成反比

• 因此，監測 DO2 與 VO2可以得知心血管系統供需平衡的狀況

Types of monitorings

• Clinical assessments: PE, CRT, GCS…

• Laboratory tests: ABG, lactate…

• Non-invasive monitoring: EKG, SpO2, NBP, Echo

• Invasive monitoring: ABP, CVP, Swan-Ganz

• Cardiac monitoring

• Respiratory monitoring

• Monitoring neurologic function

• Interactions of organ systems

監測之時機與項目• What?

• How?

• When? How frequent?

• Logical approach to monitorings

–功能決定目標–監測目標是否達成–監測是否有心肺腦及其他系統之併發症產生

• The goals and principles of ICU monitoring

• Characteristics of monitoring critically ill children

• Cardiovascular monitoring

• Respiratory monitoring

• Cerebral monitoring

• Conclusions

Characteristics of monitoring children• Children are smaller

– Every organs are smaller

– Difficult in obtaining invasive accesses

• Children are fragile– Barotrauma

– Complications of invasive procedures

• Structural problems– CHD– Airway stenosis

• Non-conventional therapies– HFOV– NO, surfactant, liquid,

ECMO

• Children are developing– Poor communicating– GCS– Different normal value

Patient (2yo) in Car Accident

• The patient developed following conditions:– Hemorrhagic shock

– Altered mental status

– Short of breath and desaturation

Patient (2yo) in Car Accident

• FiO2=1.0• pH=7.35• PaCO2=47• PaO2=50• SaO2=83%• PIP/PEEP=30/9

• BP=80/50(60)• CVP=10• CI=2.5• ICP=15• CPP=45• GCS=10

• The goals and principles of ICU monitoring• Characteristics of monitoring critically ill

children• Cardiovascular monitoring

– Perfusion– Hemodynamics

• Respiratory monitoring• Cerebral monitoring

Perfusion

• The blood flow and oxygen delivered to the tissue bed.

• Capillary refill time: weakly correlated

• Lactate: lactic acidosis

• Gastric intramural pH (tonometry)

Lactic acidosis and outcome of ECMO

Cheung et al. CCM 2002; 30:2135-2139

Gastric intramural pH (Tonometry)

Gastric tonometry and septic shock

Krafte-Jacobs et al. Chest 1995; 108:220-225

心輸出量的評估• 心輸出量＝脈搏次數心搏容積• 心搏容積與以下三參數相關• Preload前負荷 =心臟收縮前內部血液容積• Myocardium Contractility心肌收縮力 =心臟幫浦的力量

• Afterload後負荷 =心臟射出血液所面對的阻力

Hemodynamic Monitoring

• Gold Standards: indicator dilution methods– Fick method: CO=O2 consumption/avDO2– Dye dilution: Indocyanine green– Thermodilution: Swan Ganz, PiCCO

• Alternatives:– Doppler techniques– Bioimpedance

Fick Method

非侵入性監測 NICO

Hemodynamic monitoring

• Pulse rate and strength, skin temperature, capillary refill time, core-peripheral temperature gap

• EKG monitor, CXR, NBP• Echocardiography, • ABP, CVP, SvO2• Pulmonary artery floating catheter, cardiac

catheterization,

如何測量 Hemodynamics?

Thermodilution and Cardiac Output

非侵入性監測： PiCCO

PiCCO: Gödje et al. Crit Care Med 2002 Vol. 30, No. 1

非侵入性監測： Hemosonics

非侵入性監測： Hemosonics

非侵入性監測：Impedance Cardiography

ECG

generator

measuring

measuringgenerator

ECG

Principle Method Advantages Disadvantages

Fick Colorimetry Accurate Require MVO2, error when ETT leak, PTX, FiO2>0.5

NICO Accurate, non-invasive

>20kg, hypercapnea

Dilution PA Accurate, semi-continuous

Affect by respiration, difficult for children, complications, RL CO

Trans-pulmonary

Easy for small p’t, continuous

Require dedicated A line, safe duration?

Dye Accurate Sequential measurement limited by dye clearance,

Lithium Accurate, use pre-existing CV/A line

Toxicity, blood sampling

Doppler Echo Structural and function Expertise, users variations

Trans-esophageal

Continuous, rapid insertion, less invasiv

Probe fixation, individual errors, tracked accurately

Bio-impedance

Non-invasive Doubtful accuracy in critical illness

Disadvantages of invasive cardiovascular monitoring

• Difficult to obtain access• Malposition: arterial puncture (2-16%). • Pneumothorax (incidence 2-4%)• Arrhythmias. • Knotting. • PA rupture with a mortality rate of 50%. • Infection• Thromboembolisms

非侵入性心輸出量之評估方法• 理學檢查

– Perfusion:微血管回填時間、肢端脈搏、尿量

–皮膚溫度、顏色(發紺、蒼白 )

• 心輸出之評估–心電圖– *血壓計– *超音波

• Perfusion– MvO2– Gastric

Tonometry

Tips for cardiovascular monitoring

• The influence of PEEP on PAOP (or CVP): Do we have to disconnect ventilator to measure CVP and PAOP?

• Can pressure represent volume (the true preload)? Or can any preload parameters predict the response to fluid challenge?

tPAOP = eePAOP [PEEPtot (PAOP/ Palv)]

Paw

cmH2O

PAP/PAOP mmHg

disconnection

Palv

PAOP

Nadir PAOP

Teboul et al. CCM 2000, 28(11); 3631-3636

CVP, PAOP and preload

• No correlation between CVP, PAOP and RVEDVI, LVEDVI or stroke volume index

• The post saline infusion changes of CVP and PAOP have no correlation with SVI

• SVI LVEDVI, SVI LVEDVI• Initial CVP does not correlate with PAOPPAOP CVP

• Kumar et al. CCM, 2004; 32:691-699

Response to fluid challenge

• Respiration variation in CVP predict response to fluid challenge

• Magder et al. J Crit Care 1992; 7:76-85

• Respiratory changes in arterial pulse pressure can predict response to fluid challenge

• Michard et al. Am J Respir CCM 2000; 162:134-138

Respiratory variations in CVP predict response to fluid challenge• 33 ICU patients

– 12 spontaneous ventilation– 21 positive-pressure ventilation

• Spontaneous inspiratory effort > 2mmHg decrease in PAOP

• Predictor: inspiration-associated decrease in Pra 1mmHg POSTIVE response– < 1mmHg NEGATIVE response

• Challenge: 250-500ml NS infused until Pra increased by 2 mmHg

• Positive response: increase in cardiac output > 250ml/min• Magder et al. J Crit Care 1992; 7:76-85

Respiratory Changes in Arterial Pulse Pressure and Fluid Responsiveness

Michard et al. Am J Respir Crit Care Med Vol 162. pp 134–138, 2000

• The goals and principles of ICU monitoring

• Characteristics of monitoring critically ill children

• Cardiovascular monitoring• Respiratory monitoring• Cerebral monitoring

Respiratory monitoring

• Oxygen content/Gas exchange• CaO2=(1.34HbSaO2+0.003PaO2)• 即使少量增加 Hb 與 SaO2 可以明顯影響 CaO2

• 增加 SaO2 可提高 CaO2 ：例如可增加 FiO2, PEEP

• 監測 Hb, SaO2, PaO2

Respiratory monitoring

• 監測異常的 CaO2 與 CO2排除不能• 監測異常的肺換氣動力學• 監測併發症發生之可能性• 侵入性監測

ABG, IABG• 非侵入性監測

Pulse oximeter, SpO2, ETCO2, PtcO2, Ventrak mechanical graphics

How to interpret and use ABG

• pH, PaCO2, PaO2, HCO3, BE, SaO2

• PaCO2= （ VCO2×0.863 ） ÷VA

• A-a gradient=PAO2-PaO2=FiO2(PB-47)-PaCO2/k-PaO2

• CaO2=(1.34×Hb×SaO2)+(0.003×PaO2)

• pH=pK+log[HCO3/0.03(PaCO2)]

• IABG? CBG? VBG?

Yildizdas et al. Arch Dis Child, 2004; 89:176-180

R2=0.994

R2=0.995

R2=0.957

R2=0.975

R2=0.945

R2=0.981

R2=0.996

R2=0.990

116 patients in NICU and PICU, compare ABG, VBG (Central venous)and CBG

Pulse Oximetry

The limit of pulse oximetry

• Dyshemoglobinemias– COHb– metHb

• Light leakage• Dyes• Low SaO2 (<70%?)• Hb < 3g/dL• Hypotension

– < 30mmHg

• Nail polish– Blue and black 3-5%

• Venous pulsation• Probe mal position• Motion artifact• Skin pigmentation

– Melanin

– bilirubin

End-tidal CO2

Area p=q

X=alveolar ventilation, Y=alveolar dead space, Z=airway dead space,

Y+Z

X+Y+Z Vd/Vt=

Vd/Vt: Clinical for Extubation Hubble , CCM , 2000. Extubation determined by the clinical team using standard clinical assessment. Minimal vent settings for extubation: -FiO2 0.40 -PEEP 7cm H2O -PIP 30cm H2OPrior to extubation , Vd/Vt was calculated from a single breath CO2 waveform. (CO2SMO Plus Monitor , Novametrix Medical Systems)

Results: Individual Outcomes

Vd/Vt Successful

Extubation

Failed

Extubation

0.10-0.50 24/25(96%) NIV(1)

0.51-0.64 6/9(67%) NIV(3)

0.65-0.95 2/10(20%) NIV(6),PPV(2)

P<0.001

Transcutaneous pO2

Skin surface Epidermis Dermis

Artery

Vein

100 mmHg

0 mmHg

40-42C

30 C

27 C

The limit of transcutaneous blood gas

• Dissociate with arterial CO2 in shock or hypothermia

• The electrode is heated to 38-44C and increase local CO2 production, capillary CO2 solubility and diffusion through the stratum corneum,

• Risk of burn.• Adjunct to ABG , HFOV

Mechanical graphics

0 15 30 45

75

150

250

Airway Pressure(cmH2O)

Volu

me(m

l)

Vt=145ml

PEEP

PIP=42

2Y ARDS

Low compliance

Dynamic compliance=Vt/(PIP-PEEP)=3.9

Ins

Exp

Mechanical graphics

0 15 30 35Airway Pressure(cmH2O)

75

150

250

Volu

me(m

l)

Vt=145ml

PEEP

Dynamic compliance=Vt/(PIP-PEEP)=7.6

PIP=29

Exp

Ins

Tidal Volume DeterminationCannon , AJRCCM , 2000.

Population: PICU pts<16yrs old(n=98) Ventilator circuit: -infant: n=70 ; 2.8± 2.3mos -pediatric: n=28 ; 7.3± 5.6 yrs Ventilator:SV300(Siemens) Pneumotach -placed between ETT & vent circuit -CO2SMP Plus Monitor (Novametrix)Effective Vt = Vt at exp valve [circuit compliance ﹣ (PIP-PEEP)]

Results: Infant Circuit

Vt(ml) p

Exp valve Vt 70.4 ± 31.1

Calcuated Vt 59.2 ± 28.8 <0.0001

Pneumotach Vt 39.4 ± 21.5 <0.0001

The Vt as measured at the ETT was onaverage only 56% of that measured at theexpiratory valve of the ventilator.

Vt(ml) p

Exp valve Vt 185.4 ± 96.6

Calcuated Vt 167.8± 94.6 0.16

Pneumotach Vt 135.3± 75.8 0.03

Results: Pediatric Circuit

The Vt as measured at the ETT was onaverage 73% of that measured at the exp.valve of the ventilator.

• The goals and principles of ICU monitoring

• Characteristics of monitoring critically ill children

• Cardiovascular monitoring

• Respiratory monitoring

• Cerebral monitoring

腦監測 • 腦功能

– GCS, EEG, BIS

• 監測腦灌流供需功能– CBF, Autoregulation, CMRO2

• 防止二度傷害–避免腦缺血 Cerebral Ischemia–預防 /避免高危險狀況

ICP, °C, hypo or hyper-glycemia

腦監測

• 項目• Brain function

• CBF, CPP

• CMRO2

• ICP

• General clinical

• 方法• GCS, BIS, EEG

• TCD

• NIRS

• JV Saturations

• ICP monitor

腦功能之監測• Glasgow Coma Scale: different scoring

according to AGE, infants, children, adult

• Continuous EEG monitoring

• Processed electroencephalogram. Use a one lead EEG to evaluate the awareness of patients during anesthesia: BIS or AEP

Bispectral IndexHsia et al. Ped Neurol 2004; 31: 20-

23

R=0.8, p<0.05

腦血流量監測

0

1020

3040

5060

70

Reduced Normal Elevated

GR/MDSD/PVSDead

CBF Groups

% of Patients

CBF vs. Glasgow outcome score: 3 months post injuryRobertson et al. 1992

腦血流量監測

• CBFCPP(cerebral perfusion pressure)=MAP-ICP(CVP, if CVP>ICP)

• 經顱骨超音波都卜勒監測 -TCD

• 遠紅外線監測 -NIRS-Near Infrared Spectroscopy

• Jugular vein saturation monitoring

Impaired Pressure-Flow AutoregulationMaximal Normal MaximalVasodilation Autoregulation Vasoconstriction

0 25 50 75 100 125 150 CPP (mmHg)

CBFUnexpected Ischemia

Unexpected Hypermia

Normal AutoregulationDisrupted AutoregulationPartial Disrupted Autoreg

經顱骨超音波都卜勒監測 -TCD

• 優點：–非侵入性–可連續監測 *

–可知道腦血管阻力

• 缺點：–執行者之技術與探頭位置

–血流速度而非流量–定性而非定量–無法分辨 ICP與 CBF

監測血流速度改變頻率之訊號

經顱骨超音波都卜勒監測 -TCD

腦血流速率

CPP遞減

Systolic velocity

Diastolic velocity

Reversal of diastolic flow

Reductions in CPP Diastolic Velocity Systolic Velocity Reversal of Diast Vel. Oscillating Pattern

經顱骨超音波都卜勒監測 -TCD

PulsatilityIndex (PI)

ICPPI = Vel(syst) - Vel(diast) / Vel(mean)

TCD Pulsatility Index is a Nonspecific Marker of ICP

遠紅外線監測 -NIRS

• 優點：–非侵入性–定量–可監測代謝率– HbO2

/DeoxyHb

• 缺點：–顱骨厚度不同–腦直徑大小不同

– Hb異常會影響結果

Pulse oximeter for the brain

遠紅外線監測 -NIRS

010203040506070

0 10 20 30 40 50 60 70

R2 = 0.83NIR

Xe 133 Clearance

腦代謝率 CMRO2 之監測• CMRO2=CBFAVDO2(CaO2-CjvO2)• CMRL=CBF AVDL(The difference of

lactate in artery blood and jugular venous blood)

• LOI= AVDL/AVDO2• 當 LOI<0.08 ， CMRO2是恆定的，而

CBF 與 AVDO2成反比• 當 LOI0.08表示腦代謝增加，上述不

真。

腦代謝率 CMRO2 之監測

CMRO21.81.51.20.90.60.30

0 0.4 0.8 1.2

2.0

4.0

6.0

CBF(ml/gm/min)

AV

DO

2(m

ol/ml)

ischemia

infarction hyperemia

normal

hypo- perfusion

Robertson J of Neurosurg 1989

侵入性的 DO2 評估Jugular bulb catheter

Transverse sinus

Jugular bulb

At about the level of mastoid process Internal

jugular vein

SCM muscle

SjvO2 monitoring in PICU

• Total number: 20 • Major diagnoses :

– Close head injury :4/20 (20%)– Meningoencephalitis: 11 /20 (55%) – EV 71 with cardiopulmonary failure : 5/20

(25%)

• Oxygen extraction ratio (OER)=(SaO2-SjvO2)/SaO2, normal:24-42%

Episodes of Increased OER (I)

P’t No. OER>40% episodes/pt

Head injury 2/4 2/2

Meningoencephalitis

6/11 9/6

EV 71 with PE 2/5 3/2

Total number 10/20 14/10

Clinical Condition Correlated with Increased OER

• BP– 5 episodes : hypertension– 4 episodes : hypotension – 1 episode: normotensive

Restore OER

• 10ml/kg normal saline challenge or blood transfusion for each increased OER episodes when CVP 9 mmHg in ≦6 episodes

• Mannitol infusion in 2 episodes• Adjust intropic agents in 2 episodes• All patients restored OER after

managements

0

50

100

150

200

250

Time(Hr) 0

0.5

0.75 3.5

4.5

8.5

10.5

14.5

18.5

22.5 26 27 28

30.5

32.5

38.5

40.5

42.5 46 50

0

20

40

60

80

100

120

140HR

SaO2

GCS

SBP(mmHg)

CVP(mmHg)

SjvO2

1yo EV71 patient witbh jugular catheter in place

No difference in dopamine and epinephrine inf rate

NS 150ml at 0.75hr, 300ml at 22.5hr, 150ml+RBC1U at 40.5hr

顱內壓監測• 腦室內監測 : Gold Standard

–整體壓力 Global Pressure - mean of entire brain–治療 - drainage

• 腦實質內或硬腦膜下監測 : Fiberoptic–局部壓力 Regional Pressure - local tissue–無治療性 Not Therapeutic–併發症較少

bleeding (0.5 vs. 1-6%) infection rate

顱內壓順應性之變化曲線

顱內容積

顱內壓

危險區

高危險區

低順應性：

少許容積之變化即可能造成嚴重壓力變化！

顱內壓曲線P1 P2 P3

P1 P2 P3

正常順應性

順應性變低

Age SBP/DBP MAP CPP ICP

1-3 days 64/41 50 (38-62) 40 1.5-6 mmHg

1mo-2 yr. 95/58 72 (65-86) 62  

2-5 yr. 101/57 74(65-85) 64 3-7 mmHg

6-7 yr. 104/55 71(65-91) 61  

8-9 yr. 106/58 74(65-94) 64  

10-11 yr. 108/60 76(65-96) 66 10–18 mmHg

12-13 yr. 112/62 79(65-98) 69  

14-15 yr.Boys Girls16-18 yr.Boys Girls

116/66112/68121/70110/68

83(65-103)83(65-98)

87(65-104)82(65-98)

73737772

 

0

20

40

60

80

100

12019:40

21:25

21:50

00:30

01:00

03:00

05:00

07:49

10:00

13:00

15:05

17:00

21:00

01:00

09:00

09:10

09:40

11:00

13:00

14:30

17:00

19:00

21:00

01:00

03:00

05:00

07:00

09:00

11:00

15:00

17:50

19:00

21:00

23:00

01:00

03:00

05:00

07:00

09:00

11:00

13:00

15:00

17:00

21:00

01:00

03:00

05:00

09:00

11:00

12:00

13:00

15:00

17:28

20:00

01:00

03:00

05:00

09:00

11:00

13:00

15:00

17:00

19:00

21:00

01:00

05:00

11 11月 日 11 12月 日 11 13月 日 11 14月 日 11 15月 日 11 16月 日 11 17月 日 11 18月 日

Midazolam before suction since Nov 13 9:00Dopamine 50mg in D5w20cc run 1ml/hrBomin 2mg in16cc run 0.1ml/hrHyperventilation on Nov.12 8:25am, off Nov.14 12:00Thiopental 84 mg in 16.6 cc run 1.5 cc/hr Nov.14 16:00

----ICP----CPP----MAP----CVP

腦監測應用於治療• 降低腦部代謝

– Mild hypothermia:– 33-35ºC–控制痙攣、減少刺激– Sedation/analgesics?

midazolam, morphine, phenobarbitalthiopental,注意 BP

• 增加氧氣運送–增加 FiO2–增加 Hb–增加心輸出量– Preload:CVP>10避免過高 CVP

– Contractility– Afterload

腦監測應用於治療• 減少顱內壓

–使用Mannitol/ furosemide以維持滲透壓 310-320mOsm以上

–控制換氣，維持 PaCO2:30-35mmHg

• 增加 CPP–增加心輸出量–當心輸出量足夠時，使用血管升壓素如norepinephrine以增加血壓

Conclusions

• Early diagnosis and identification of the problem• Anticipation of possible events and complications• The holistic approach to a critical illness: • The considered use of technology• Primum non nocere• Recognition of the limits of critical care