Shock in newborn

1. Neonatal shock and hypotension
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2. OBJECTIVES
Background
Pathophsiology of shock _mechanisms of shock
_cardiac output assessment and tissue perfusion
_physiological heart rate
Clinical essentials in management of shock
Goal oriented targeted management
Role of echocardiography in management of shock
conclusion

3. Definition of shock
Shock is a pathophysiologic state characterized by an imbalance between oxygen
delivery and oxygen demand in the tissues leading to tissue hypoxia.
The initial compensated phase is characterized by neuroendocrine compensatory
mechanisms
The blood flow and oxygen supply to vital organs are maintained at the expense of
non-vital organs.

4. PATHOPHYSIOLOGY OF NEONATAL SHOCK
Myocardial dysfunction, abnormal peripheral vasoregulation and hypovolemia leading to decreased delivery
of oxygen and nutrients to tissues are often the primary sources of neonatal shock. This is often complicated
by relative adrenal insufficiency often seen in the premature infant.
The neonatal myocardium has
fewer contractile elements compared with older children and adults
immature myocardium has a higher basal contractile state
higher sensitivity to changes in afterload
other features:
higher water content
greater surface-to-volume ratio
reliance on extracellular calcium stores

5. PATHOPHYSIOLOGY OF NEONATAL SHOCK
The vascular smooth muscle tone and its complex regulation play a key role in pathogenes
is of neonatal shock.
A balance of the vasodilating and vasoconstricting forces regulates the tone
Commonly described factors include vasopressin, nitric oxide, eicosanoids,
catecholamines, and endothelin
Pathophysiology of shock in newborns is unique since it is associated with physiologic
transition from fetal circulation to neonatal circulation at birth.
Suprasystemic pulmonary vascular resistance (PVR) in the prenatal period may remain
elevated, especially in the presence of ongoing hypoxia and acidosis from sepsis, leading
to persistent pulmonary hypertension of the newborn (PPHN).

6. PATHOPHYSIOLOGY OF NEONATAL SHOCK
Relative adrenal insuffiency
there is plenty of evidence suggesting low cortisol
levels in sick term, late preterm, and preterm infants
. Both adrenal insufficiency and decreased vascular
responsiveness to catecholamines can contribute to
vasopressor resistant shock. Low dose steroids hav
e been found to improve cardiovascular
status in infants with vasopressor resistant shock, f
urther supporting the role of relative adrenal
insufficiency
Hydrocortisone for hypotension and vasopressor dependence in preterm
neonates: a meta-analysis. J Perinatol (2010) 30:373–8. doi:10.1038/jp.2
009.126

7. Assessment of cardiac output (CO) and tissue perfusion
It is known that BP = CO × SVR.
Both BP and CO can be measured.
SVR is a derived value from the above
equation.
CO = (HR) × (SV).
SV depends on preload, myocardial
contractility, and afterload conditions .

8. Assessment of cardiac output (CO) and tissue perfusion
Measurement of myocardial contractility using load dependent measures such as
fractional shortening (FS) can be affected by the right ventricular dominance characteristic of fetal
circulation
Appropriate assessment of myocardial activity requires measurement of load independent measures
such as relation between velocity of circumferential fiber shortening and left ventricle (LV) wall stress
Indices.
Blood pressure monitoring, preferably measured invasively can offer continuous real time assessment
of the CO .

9. Measuring blood pressure
Blood pressure monitoring, preferably measured invasively can offer continuous real
time assessment of the CO
Invasive arterial blood pressure in the neonatal intensive care: a valuable tool to manage very i
ll preterm and term neonates
Michelina Di BiaseEmail author,
Anna Casani and
Luigi Orfeo
Italian Journal of Pediatrics201541(Suppl 1):A9
https://doi.org/10.1186/1824-7288-41-S1-A9
© Di Biase et al. 2015
Published: 24 September 2015

10. Measuring blood pressure
lack of consensus definition of hypotension in the neonate continues to be a major hindrance to
the use of BP as an adequate measure for such an assessment (CO)
BP may be affected by demographic factors such :
 Birth weight
 Gestational age
 Postnatal age
coexistent clinical factors such as :
 antenatal steroids
 PDA
 Level of respiratory support
 Therapeutic hypothermia.
Mean BP value less than the gestational age in weeks is often considered adequate in the first few days of life
, but this is rather simplistic since thresholds may vary between different patients, and at different time points
in the same patient. Hence, attention must be paid to additional measures of perfusion.
Dempsey EM, Barrington KJ (2006) Diagnostic criteria and therapeutic interventions for the hypotensive very low birth weight infant. J Perinatol 26:677–681

11. Measuring blood pressure
BP is directly affected by SVR, which in turn is regulated by multiple factors including drugs,
sepsis, temperature, and hormonal changes. Hence, it may not be the best measure of tissue
perfusion.
In addition, presence of intra-atrial and ductal shunting may not allow the assumption that
ventricular output is an accurate measure of systemic blood flow
Evans N, Iyer P. Assessment of ductus arteriosus shunt in preterm infants supported by mechanical ventilation: effect of interatrial
shunting. J Pediatr (1994) 125:778–85. doi:10.1016/S0022-3476(06)80183-6
Arguably, flow is a better indicator of perfusion than the BP that drives the flow to the organs.
However, flow measures such as LV and right ventricle (RV) output may not be accurately depictive of organ blood flow i
n VLBW infants due to the presence of above mentioned shunts in the transitional period. SVC flow may be used as a
valid indicator of cerebral blood flow
Kluckow MR, Evans NJ. Superior vena cava flow is a clinically valid mea-surement in the preterm newborn. J Am Soc Echocardio
gr (2014) 27:794. doi:10.1016/j.echo.2014.04.002

12. CLINICAL ESSENTIALS IN MANAGEMENT OF SHOCK
Key to the management is early recognition and identifying the underlying pathophysiology of shock.
The earlier findings include :
 pallor
 poor feeding
 tachycardia
 tachypnea
 temperature instability.
 hypotension is a late finding in neonatal shock.
In addition, other late features may include weak peripheral pulses, low ScvO2, signs of decreased
peripheral perfusion such as acidosis, elevated lactate.
In spite of being a late finding, hypotension is the most commonly used determinant of decreased
perfusion in NICU given the ease of monitoring

13. CLINICAL ESSENTIALS IN MANAGEMENT OF SHOCK
List of the parameters used for assessment of neonatal shock.
Capillary refill time
Urine output
Heart rate
Blood pressure
Presence of lactic acidosis
Central venous pressure
Mixed venous saturation
Arterio venous oxygen difference
Conventional parameters (commonly
used in standard practice)
Functional echocardiography Near
infrared spectroscopy
New parameters (now being used in
clinical Practice)
Electrical cardiometry
Visible light spectroscopy
Perfusion Index
Functional cardiac MRI
Novel parameters (research tools at this t
ime, not being used in clinical practice)

14. Therapeutic end points for the management of shock
The ACCM guidelines have established goals and therapeutic end points for the management of
shock in both delivery room and subsequently in the NICU.
The therapeutic end points in the first hour of resuscitation include:
 CRT ≤ 2 s,
 Normal and equal central and peripheral pulses
 Warm extremities
 Urine output >1 ml/kg/h
 Normal mental status
 Normal BP for age
 Normal glucose, and calcium concentrations
Along with consideration of interventions to increase BP, attention should be paid to conditions
contributing to hypoperfusion. These may include but not limited to patency of ductus arteriosus,
sepsis, excessive mean airway pressure, pneumothorax, and adrenal insufficiency.

15. PATHOPHYSIOLOGY OF NEONATAL SHOCK
Mechanisms of shock Causes of shock
Types of neonatal shock
Mechanism for poor tissue
perfusion
Sepsis, endothelial injury, and vasodilators
Distributive shock
Abnormalities within the vascular
beds
Congenital heart disease, heart failure,
arrhythmia, cardiomyopathy, and
postcardiac surgery/post-patency of the
ductus arteriosus ligation
Cardiogenic shock
Defects of the pump
Blood loss from infants or placenta around
birth of infants
Hypovolemic shock
Inadequate blood
volume
Cardiac tamponade, pneumothorax, high
pulmonary vascular resistance restricting
blood flow such as in persistent pulmonary
hypertension of the newborn, pulmonary
hypertension
Obstructive shock
Flow restriction
Methemoglobinemia and severe anemia
Dissociative shock
Inadequate oxygen-releasing capacity

16. Hypovolemia is rarely the primary cause of hypotension in the VLBW infant in the first few days of life,
unless there is clear history of perinatal blood loss
excessive fluid administration may be associated with adverse outcomes such as PDA, chronic lung d
isease, and mortality .
Volume support can increase preload and hence CO. Hence, in the absence of hypovolemia, volume
support of 10–20 ml/kg over 30–60 min may be reasonable. Functional echocardiography can be of a
ssistance in determining volume status and following changes with intervention
HYPOVOLEMIA

17. Abnormal vasoregulation
Abnormal vasoregulation is the major contributor to neonatal shock.
Vasopressor–inotropes, inotropes, and lusitropes have been extensively used in the management of neonatal shock,
surpris-ingly without robust data directing such management.
Dopamine and epinephrine are vasopressor–inotropes and as such, increase both SVR and myocardial contractility.
Dobutamine is an ino-trope with a variable peripheral vasodilatory action.
Milrinone is also an “inodilator” that decreases peripheral vascular resistance but with variable inotropy in newborns
due to its age depend-ent hemodynamic effects .Its use has been described with coexistent pulmonary hypertension .
Phenylephrine and vasopressin are two pure vasopressors and can be of benefit in catecholamine resistant
vasodilatory shock.
Vasopressin has been recently discussed to have added benefit in the management of hypotension associated with p
ersistent pulmonary hypertension given the pulmonary vasodilatory action mediated via V1 recep-tors, but more data ar
e needed before recommendations can be given for wider use

18. Abnormal vasoregulation
Commonly used inotropes and vasopressor drugs It is prudent to understand their site of action and
hemodynamic effects while managing critically ill infants with hemodynamic instability.

20. Commonly used inotropes and vasopressor drugs
in neonatal shock.
Hemodynamic effects
Site of action
DOSE
NAME OF DRUG
Renal & mesenteric dilatatio
n
Inotropic effect
Vasopressor,increase SVR&
PVR
Dopaminergic receptors 1&2
@ receptors
B receptors
1-4 mic/kg/min
4-10 mic/kg/min
11-20 mic/kg/min
DOPAMINE
Inotropic effects decrease SV
R increase CO
B1&B2
On @ receptors
5-20 mic/kg/min
DOBUTAMINE
Inotropic effects decrease SV
R
Vasopressor eff increase SVR
@1receptors
B1&B2 receptors
0.02-0.3 mic/kg/min
0.3-1 mic/kg/min
EPINEPHRINE
Vasopressor effects increase
SVR
@1&@2 receptors
0.1 -1 mic/kg/min
NOREPINEPHRINE
UNCERTAIN
Enhance sensitivity to catechola
mines
1-205 mg/kg 4-6 hourly
HYDROCORTISON
E
Increase SVR no inotropic eff
V1 receptors
0.018-0.12 u/kg/h
VASOPRESSIN
Inodilator eff,lusitropic effect
s increase contractility and
decrease SVR
Phosphodiesterase III inhibitor a
nd produce effect at B1&B2
50-75 mic/kg/min bolus followed by
0.25-0.75 mic/kg/min
MILRINONE
Inodilator eff ,increase contra
ctility without increasing myo
cardial demands
Multiple action including phosp
hodiesterase inhibitor effect
6-24 mic/kg/min bolus followed by
0.1-0.4 mic/kg/min
LEVOSIMENDAN

21. TREATMENT
SVR
Afterload
Cardiac output
CO
Preload
PCWP
red arrow indicate p
rimary abnormality
IV FLUIDS
Hypovolemic shock
INOTROPES
REVASCULIZATION
Cardiogenic shock
PRESSORS
IV FLUIDS
Distributive shock

22. CLINICAL PATHOPHYSIOLOGIC APPROACH
SUGGESTED MANAGEMENT AND THE E
XPECTED IMPACT ON RECOVERY
DISEASES
PATHOPHSIOLOGIC MECHANISM
MEASURED OR CALCULATED PARAMET
ERS
1-INITIATE TRANSIENT SUPPORT BY VO
LUME EXPANDER THEN START DOBUTA
MINE AND WATCH FOR SBP & DBP
2-IF NO RESPONSE WITH 10 MIC/KG/M
COSIDER EPINEPHRINE AS 2ND LINE
3- PULMONARY VD IN PH
1-HYPOXIC ISCHAEMIC INSULT
2-HIGH AFTERLOAD :DECOMPENSATED
TRANSIENT CIRCULATION OR POST PD
A LIGATION
3-LOW PRELOAD LOSS OF VOLUME IN
3RD SPACE OR HIGH PVR(PH)
LOW CARDIAC OUTPUT
SYSTOLIC ARTERIAL<95TH CI FOR GA WI
THNORMAL DBP
(NARROW PULSE PRESSURE)
1- INITIATE TRANSIENT SUPPORT WITH
VOLUME EXPANDER THEN START DOP
A FOR 10 MIC/KG/M CONSIDER NOR
EPINEPHRINE OR VASOPRESSIN AS 2ND
LINE
1-SEPSIS ,NEC ,
2- LOW PRELOAD
LOW PERIPHERAL VASCULAR RESISTEN
CE
DIASTOLIC ARTERIAL <95TH CI FOR GA
WITH NORMAL PULSE PRESSURE
1-INITIATE TRANSIENT SUPPORT BY VO
LUME EXPANDER THEN START EPINEPH
RINE COSIDER EARLY TNE
ADVANCED ANY OF THE ABOVE CONDI
TIONS
LOW CRDIAC OUTPUT AND LOW PERI
PHERAL VASCULAR RESISTANCE
BOTH SYSTOLIC AND DIASTOLIC <95TH
CI FOR GA WITH NARROW PULSE PRES
SURE
COSIDER CORTICOSTEROIDS IF VASOA
CTIVE INOTROPIC SCORE > 10 WITH N
O IMPRVEMENT
SUPRARENAL DYSFNCTION OF PREMAT
URITY OR LATE ONSET COMPROMISED
SYSTEMIC CIRCULATION OF PRETERM
INSUFFICIENT SUPRARENAL RESPONSE
TO STRESS
RANDOM CORTISOL <350 NMOL/L

23. ROLE OF ECHOCARDIOLOGY IN SHOCK
Fast cardiac ultrasound (FoCUS)/focused echocardiography in shock
echocardiographic assessment
TYPE OF ASSESSMENT
Cardiac filling by “eyeballing
Assessment of inferior vena cava for collapsibility to assess hypovolemia
Visual assessment of volume overloading
Cardiac function assessment on visualization
Cardiac tamponade or pericardial effusion
Qualitative assessment of
cardiac function and filling
Hypertrophy and/or dilatation of right ventricle
Flattening of interventricular septum
Right to left or bidirectional shunt across patent ductus arteriosus
Bidirectional shunt across foramen ovale
Qualitative assessment of
pulmonary hypertension
Assessment of pulmonary artery systolic pressure (PAP) by assessing tricuspid valve regurgitation
Right ventricle to left ventricle (LV) ratio
Eccentricity index
“Fast” quantitative assessment
of pulmonary hypertension
LV fraction shortening (FS%) •
Tricuspid annular plane systolic excursion
Fast” quantitative assessment of
cardiac function

24. ROLE OF ECHOCARDIOLOGY IN SHOCK
Assessment on cardiac filling on visual inspection “eyeballing.” Images (A,B) show under-filled heart in apical 4 cham
ber (A4C) and parasternal long axis (PLAX) views. Images (C,D) show volume overloading of left atrium (LA) and left v
entricle (LV) in A4C and PLAX views.

25. ROLE OF ECHOCARDIOLOGY IN SHOCK
Physiological variation in inferior vena cava (IVC) diameter. Normal collapsibility of (A) IVC during inspiration (Dmin) and (B) expansi
on during expiration (Dmax). In hypovolemia, IVC may be collapsed while in hypervolemia there is minimal or no collapsibility

26. ROLE OF ECHOCARDIOLOGY IN SHOCK
Pericardial effusion in (A) subcostal and (B) apical 4 chamber views. In large pericardial ef
fusion and cardiac tamponade, there may be collapse of cardiac chambers—first seen coll
apse of right atrium followed by right ventricle

27. ROLE OF ECHOCARDIOLOGY IN SHOCK
Interventricular septum (IVS) and left ventricle (LV) shape in pulmonary hypertension on visual inspection. Ima
ge (A) shows normal circular LV and IVS shapes. Image (B) shows right ventricular dilatation and hypertrophy
of right ventricle, flattening of IVS and “D” shaped LV in pulmonary hypertension

28. ROLE OF ECHOCARDIOLOGY IN SHOCK
Quantitative assessment of pulmonary artery systolic pressure (PAP) by measuring tricuspid valve regurgitati
on velocity [tricuspid regurgitation (TR) jet]. PAP = right atrial (RA) pressure + pressure gradient between RA a
nd RV (estimated by TR jet). (A) TR jet on A4C. (B) TR Doppler.

29. CONCLUSION
Shock in the newborn period is associated with unique pathophysiologic
states that need careful assessment and individualized approach for
management.
Early recognition of shock and its underlying pathophysiology is critical in
instituting early target specific intervention, which may improve outcomes
in patients with neonatal shock.
A focused bedside functional echocardiography can provide vital anatomic
and physiologic information to such management

30. References
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