The Limits of Viability-How Small Is Too Small.ppt

Limits of Viability in Preterm

1. The Limits of Viability:
How Small Is Too Small?
Istvan Seri M.D., Ph.D.
USC Division of Neonatal Medicine
Women’s and Children’s Hospital
LAC/USC Medical Center and
Children Hospital Los Angeles
Keck School of Medicine
University of Southern California
Los Angeles, CA

2. 1960’s- 30-31 weeks
1980’s- 26-27 weeks
2000 - 24 weeks
The Limits of Viability:
How Small Is Too Small?
Gestational age at which a newborn had a
50% chance of survival

3. Too small
Too immature
Comfort Care Only
Too big
Too mature
Unreasonable Mandatory
Active Intervention
Gray ZoneGray Zone
??? Intervention ?????? Intervention ???
The Limits of Viability:
How Small Is Too Small?

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0-12%
0-55%
23-62%
Percent Survival by Gestational Age
The Limits of Viability:
How Small Is Too Small?

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1-38%
16-37%
Percent Survival by Birth Weight
The Limits of Viability:
How Small Is Too Small?

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The Limits of Viability:
How Small Is Too Small?
Lucey et al, Pediatrics 113:1559,
2004
Percent
Outcome of Neonates with Birth Weights of 401-500 g
Gestational age = 23.3 ±2.1 weeks

7. Outcome of Neonates with Birth Weights of 401-500 g
Gestational age = 23.3 ±2.1 weeks
The Limits of Viability:
How Small Is Too Small?
Lucey et al, Pediatrics 113:1559,
2004
Total Neonates Registered
N = 4172 (100%)
Died in Delivery Room
N = 2186 (52%)
Survived DR to NICU
N = 1986 (48%)
Survival Status
Unknown N = 43 (1%)
Survived to NICU D/C
N = 690 (17%)
Died in NICU
N = 1253 (30%)
Gestational Age = 25.3 ±2 weeks

8. Outcome of Neonates with Birth Weights of 401-500 g
Gestational age = 23.3 ±2.1 weeks
The Limits of Viability:
How Small Is Too Small?
Lucey et al, Pediatrics 113:1559,
2004
Compared to patients who died in the DR, neonates who survived
to be admitted to the NICU were more likely to
1.Be female (58% vs 49%)
2.Be small for gestational age (56% vs 11%)
3.Have received prenatal steroids (61% vs 12%)
4.Have been delivered via cesarean section (55% vs 5%)

9. Synnes et al, 1994
Percent Survival by Gestational Age and Birth Weight
The Limits of Viability:
How Small Is Too Small?

10. %
Burdens of Prolonging Support in Infants at the Limits of Viability
The Limits of Viability:
How Small Is Too Small?

11. Infants born <23 weeks too immature to survive
The Limits of Viability:
How Small Is Too Small?
Comfort care only

12. Batton et al, 1998
Effect of Fetal Compromise on Survival
The Limits of Viability:
How Small Is Too Small?

13. Vermont-Oxford Network (362 Institutions)
Pediatrics 110:143, 2002
Gestational Age-Dependent Mortality (1991-1999)
The Limits of Viability:
How Small Is Too Small?

14. Parkland Memorial Hospital, Dallas, TX
Kaiser et al, J Perinatol 24:343, 2004
Birth Weight-Specific Survival of VLBW Neonates (1977-2000)
The Limits of Viability:
How Small Is Too Small?

15. Decision-Making at the Threshold of Infant
Viability Estimating Survival & Intact Survival
GA BW Survival Intact Survival*
(weeks) (g) ( % ) ( % )
23 600 50 % 25 %
24 700 70 % 70 %
25 800 80 % 80 %
26 900 90 % 70 %
27 1000 95 % 80 %
* Among Survivors

16. Infants born >25 weeks are mature enough
The Limits of Viability:
How Small Is Too Small?
Full support warranted

17. 
Target range for “Gray Zone” based on survival:
23-24 6/7
th
weeks and 500-600 g

What are the complications and outcome data of premature neonates in the
“Gray Zone”?
The Limits of Viability:
How Small Is Too Small?

18. %
Percent Severe Head Ultrasound Abnormalities by Gestational Age
The Limits of Viability:
How Small Is Too Small?

19. %
Percent Chronic Lung Disease at 36 weeks by Gestational Age at Birth
The Limits of Viability:
How Small Is Too Small?

20. Doyle et al Pediatrics, 2001
%
Percent Survival and Intact Survival by Gestational Age
The Limits of Viability:
How Small Is Too Small?

21. Bottoms et al, NICHD Network, 1997
%
Percent Survival and Intact Survival by Birth Weight
The Limits of Viability:
How Small Is Too Small?

22. The Limits of Viability
Impact of BPD, Brain Injury and ROP on 18-Month
Outcome of ELBW Infants
Outcome
Variable
Odds Ratio 95 % CI
BPD 2.4 1.8 – 3.2
Brain Injury 3.7 2.6 – 5.3
Severe ROP 3.1 1.9 – 5.0
Schmidt et al: JAMA 289:1121, 2003
These 3 common neonatal morbidities strongly predict the risk of later death or
disability

23. Overall probability of poor
outcome at 18 m (35%)
The Limits of Viability
Impact of BPD, Brain Injury and ROP on 18-Month Outcome of
ELBW Infants
Schmidt et al: JAMA 289:1121, 2003
These 3 common neonatal morbidities strongly predict the risk of later death or disability

24. VON 2000
The Limits of Viability
Pulmonary Outcome

25. VON 2000
The Limits of Viability
IVH and PVL: Incidence by Birth Weight

26. The Limits of Viability
Sequelae of Prematurity (1)Sequelae of Prematurity (1)
Place of Birth and Mortality in Canadian NICUsPlace of Birth and Mortality in Canadian NICUs
17 NICUs
Admits = 19,265
Period = 1996-97
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Birth Weight (kg)
Sankaran K et al; CMAJ 166:173-8, 2002

27. The Limits of Viability
Sequelae of Prematurity (2)Sequelae of Prematurity (2)
Place of Birth and Mortality in Canadian NICUsPlace of Birth and Mortality in Canadian NICUs
Sankaran K et al; CMAJ 166:173-8, 2002

28. The Limits of Viability
Sequelae of Prematurity (3)Sequelae of Prematurity (3)
Place of Birth and Mortality in Canadian NICUsPlace of Birth and Mortality in Canadian NICUs
Sankaran K et al; CMAJ 166:173-8, 2002

29. Non-SPC SPC*
Death (%) 16.9 14.3
BPD (%) 20.1 17.5
IVH-III-IV 15 8.4
ROP (Treated) 5.6 4.8
NEC 6.1 7.2
Warner et al; Pediatrics 2004; 113:35-41
* SPC=Subspecialty Perinatal Center
The Limits of Viability
Place of Birth and Mortality in Infants with Birth Weight of 500-1499 gPlace of Birth and Mortality in Infants with Birth Weight of 500-1499 g

30. Gestational Age
(weeks)
Adverse Outcome
(Died or abnormal at 2 years)
23 – 24 92%
25 64%
26 35%
27 – 32 18%
Rijken et al; Pediatrics 2003; 112:351-58
The Limits of Viability
Survival and 2-year Outcome in Infants <27 wks (1996-1997)

31. Hoekstra et al; Pediatrics 2004; 113:e1-e6
Gestational
Age (weeks)
Survival
(%)
% Normal at 47.5
months (n=675)
% Normal at
8 years (n=147)
23 66 52 33
24 81 59 55
25 85 66 67
26 93 66 65
The Limits of Viability
Survival and Outcome of ELBW infants born at 23-26 weeks
(1986-2000)

32. Hoekstra et al; Pediatrics 2004; 113:e1-e6
The Limits of Viability
Factors Affecting Outcome of ELBW infants at 47.5 Months of Age (1986-2000)

33. Problems with predicting long-term outcome

Adverse medium-term neurodevelopmental outcomes in ELBW infants
correlate with severe brain injury, CLD, NEC, steroid use for CLD, male
gender (Vohr et al, 1999)

However, long-term neurodevelopmental outcomes do not correlate well
with these predictors and maternal education and home environment are
more important than all other factors except severe brain injury
The Limits of Viability:
How Small Is Too Small?

34. Outcome of ELBW Infants - NICHD American Experience

Patient population of 1126 infants (BW = 501 - 800 g)

Females have a survival advantage of 90 g

SGA neonates had a survival advantage of 57 g

Antenatal steroids confer a survival advantage of 67 g
Tyson et al JAMA 1996; 276:1645
The Limits of Viability:
How Small Is Too Small?

35. Odds of Survival between 23 and 24
6/7
weeks

Chance of survival improves by 2% a day during 23 to
26 weeks gestational age

Overall, 50% survive and 50% of the survivors are
handicapped (the “50 - 50” rule)
The Limits of Viability:
How Small Is Too Small?

36. 
Recent survival data (especially on non-compromised ELBW neonates)
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Lower incidence of severe ROP, CLD and/or severe head ultrasound
abnormalities
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Overall “intact” survival has increased from <10% to > 40%

Outcome still very uncertain for individual patient especially at 23 weeks
gestational age
The Gray Zone:
23 - 24 6/7 weeks gestation and 500 - 600 grams
The Limits of Viability:
How Small Is Too Small?

37. Three approaches to care
1.Wait Until Certainty Approach Treatment
begins on every infant thought to have any chance of survival, wait until all information
is in before deciding whether continuing care is the right decision (eg: USA)
2.Statistical Approach Determine
categories of patients in which treatment may be limited or withheld (eg: Sweden)
3.Individualized Approach (eg: UK)
Clin Perinatol, 1996
The Limits of Viability
Decision Making at The Threshold of Infant Viability Decision Making at The Threshold of Infant Viability

38. <23 wks
Comfort Care Only
25 wks
Unreasonable Mandatory
Full Critical Care
Gray ZoneGray Zone
23-24 6/7 wks and 500-600 g23-24 6/7 wks and 500-600 g
Extent of active intervention based on condition
and response
Parents indicate definite wishes for non-
active intervention
(importance of counseling regarding impact of initial
condition/perinatal stress on outcome)
Parents desire active intervention or
defer to medical judgement
Follow parents wishes, unless evidence parents not
working in best interest of the baby
The Limits of Viability:
Decision-Tree

39.  500g* or
< 23wk
Gray Zone
23 - 24
6/7
wk and
500 - 599g
 600g
or  25wks
Heart rate
Low or Absent
Present >40-50
Bag/Intubate
Can’t intubate or
poor response
(HR < 60/min
for 5mins)
Discontinue interventions
& initiate comfort care
measures
HR = 60 - 100/min
Consider brief CPR,
drugs and bolus fluids x1
Poor response
HR > 100/min
Give surfactant;
insert lines;
check ABG;
start fluids
good
response
Transfer to NICU
NICU Care
Ongoing evaluation
Parents desire active management
carry on, set limits
No resuscitation
Initiate comfort
care measures
Initiate resuscitation
Clinical course will
dictate management
Poor clinical status
* The occasional infant <500g BW (usually IUGR), who is vigorous at birth may warrant active intervention
Decision-Making at the Threshold of Infant Viability

40. •The algorithm assumes appropriate antenatal counseling
•Gestational age should be determined antenatally
•Birth weight must be obtained at the time of delivery
•At each stage of resuscitation, the prognosis for reasonable
outcome should be reevaluated
•Parental wishes regarding extent of intervention in the gray
zone should be honored until parents except their baby’s fate
Decision-Making at the Threshold of
Infant Viability

41. Decision-Making at the Threshold of Infant ViabilityDecision-Making at the Threshold of Infant Viability
Relative weighting of parental, clinician and societal views of active Relative weighting of parental, clinician and societal views of active
interventionintervention with increasing gestational agewith increasing gestational age
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Parents Clinicians Society
Gestational Age at Birth

42. Questions?Questions?
Limits of Viability