Part I: Physiology & Pathophysiology - NDANA with Prematurity (Part I).pdf · xxx00.#####.ppt 4/11/16 2:07 PM Patent Ductus Arteriosus (PDA) • 50% of full-term infants close PDA

Nate Jones, CRNA, MSN

Texas Children's Hospital

Instructor, Department of Anesthesiology

Baylor College of Medicine

Problems with Prematurity

Part I: Physiology & Pathophysiology

Pediatric Anesthesiology

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Objectives

• Describe common problems associated with premature birth as they relate to the brain, eyes, lungs, heart, gut, and thermoregulation

• Review anesthetic implications as they pertain to problems of prematurity

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Conflicts of Interest • None

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Common Complications of Prematurity •  Intraventricular

Hemorrhage • Post-hemorrhagic

Hydrocephalus • Periventricular White

Matter Injury • Retinopathy of

Prematurity

•  Bronchopulmonary Dysplasia

•  Apnea of Prematurity

•  Patent Ductus Arteriosus

•  Necrotizing Enterocolitis

•  Hypothermia

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Prematurity

Gestational Age Prematurity Group Birth Weight

36-37 Weeks Borderline Premature < 2500 g Low Birth Weight

31-35 Weeks Moderately Premature < 1500 g Very Low

Birth Weight

24-30 Weeks Severely Premature < 1000 g

Extremely Low Birth Weight

(micropremies)


Peiris & Fell. 2009

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http://www.cdc.gov/reproductivehealth/MaternalInfantHealth/PDF/PretermBirth-

Infographic.pdf

http://www.marchofdimes.org/mission/prematurity-reportcard.aspx

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Head Problems

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Intraventricular Hemorrhage (IVH)

•  Incidence and severity inversely related to gestational age

• Germinal matrix • Causes of IVH are multifactorial


Peiris & Fell (2009); Ballabh (2010)

Robinson (2012). J Neurosurg Pediatrics

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Post-hemorrhagic Hydrocephalus (PHH)

•  Increase in the amount of CSF due to impaired reabsorption

• Exact mechanism of PHH is not understood • Ventriculoperitoneal (VP) shunt is the

current most common treatment mode for PHH


Robinson (2012)

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Anesthetic Implications for VP Shunt

• Supine or slightly lateral position

• Elevate HOB if ICP é •  If ICP é,

hyperventilate to PaCO2 25-30 mm Hg


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Gregory & Andropoulos (2012)

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Periventricular White Matter Injury • VLBW (<1500 g) especially at risk –  10-15% diagnosed with cerebral palsy –  25-50% have cognitive, attentive, behavioral, or

socialization problems

•  “Encephalopathy of prematurity” • Pathophysiology incompletely understood • Cause is multi-factorial

Ellit & Rosenberg (2014), Gregory & Androp[oulos (2012)

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Cerebral Palsy

• Non-progressive, changing • Movement and posture disorder • Spastic quadriparesis is most common • Multifactorial, but hypoxia

Wongprasartsuk & Stevens (2002), Gregory & Andropoulos (2012)

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Anesthetic Implications for Cerebral Palsy

• Secretions • Positioning • GERD • Scoliosis • Hypothermia • Succinylcholine

Wongprasartsuk & Stevens (2002), Gregory & Andropoulos (2012)

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Retinopathy of Prematurity (ROP)

• Progressive overgrowth of retinal vessels • Can lead to intraocular hemorrhage • Retinal hypoxia – Vascular Endothelial Growth Factor production –  vascular proliferation – hemorrhage à retinal detachment

McCann & Soriano (2014), Gregory & Andropoulos (2012)


Retinopathy of Prematurity (ROP)

• Oxygen is a major contributing factor • PaO2 150 mm Hg for as little as 1-2 hours

has caused ROP! • Preterm infants whose SaO2 was kept

between 80-96% had less ROP than those with higher SaO2

McCann&Soriano(2014),Gregory&Andropoulos(2012)


Stage of ROP Events Prognosis

1 Mildly abnormal blood vessel growth

Resolves on its own

2 Moderately abnormal blood vessel growth

3 Severely abnormal blood vessel growth

Treatment at this point has a good chance of preventing retinal detachment

4 Partially detached retina If the eye is left alone at this stage, the baby can have severe visual impairment and even blindness 5 Completely detached retina

https://nei.nih.gov/health/rop/rop


Anesthetic Implications for ROP

• Unknown if exposure to é FiO2 can worsen pre-existing ROP

• Better to target a lower SaO2 (i.e. 87-92%) • Avoid N2O in case surgeon injects air into

eye


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Heart and Lung Problems

Stages of Lung Development, Potentially Damaging Factors,

and Types of Lung Injury.

Baraldi E, Filippone M. N Engl J Med 2007;357:1946-1955.

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Bronchopulmonary Dysplasia (BPD)

•  Impaired alveolar growth • Airway inflammation • Dysplastic pulmonary vasculature • Enlarged alveoli • Fewer alveoli • Decreased septation


Peiris & Fell (2009), Gregory & Andropoulos (2012), Collaco et al (2012), Baraldi & Filippone(2007)

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Decreased septation

Alveolar Hypoplasia

Fewer, larger alveoli

DECREASED GAS

EXCHANGE


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Severity of BPD Oxygen Requirements

Mild Now on Room Air

Moderate Now needs < 30% FiO2

Severe

Now needs ≥ 30% FiO2 and/or

Positive Pressure Ventilation

Forbabiesbornat<32weeks’GAwhoareassessedathospitaldischargeor36weeksPCA,ashavingneededoxygensupplementa\onforatleast28days


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Pulmonary Arterial Hypertension (PAH)

• PAH = mPAP > 25 mm Hg at rest • Triggers for PAH crisis • Clinical picture of hemodynamic

deterioration: RV failure

Andropoulos et al (2015)

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RV failure

éRVEDV éRV wall stress

R to L septal shift

êLV performance /

SV

êCO êMAP

êcoronary perfusion

Self-perpetuating Cycle of PAH Crisis

Andropoulos et al (2015)

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Pulmonary Arterial Hypertension (PAH) • Signs and symptoms –  dyspnea –  pallor –  cyanosis –  syncope –  bradycardia –  RV heave –  bronchospasm

Friesen & Williams (2008)

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Goals & Treatment for PAH Crisis

é oxygenation ê pulmonary vasoconstriction é systemic pressure, perfusion

(Petros & Pierce, 2006)

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Goals & Treatment for PAH Crisis é  oxygenation

•  give oxygen ê  pulmonary vasoconstriction

•  hyperventilate •  pulmonary vasodilators •  relieve noxious stimuli

é  systemic pressure, perfusion •  fluid, inotropes, vasopressors

Friesen & Williams (2008), Andropoulos et al (2015), Petros & Pierce (2006)

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Anesthetic Drugs and PAH

• Benzodiazepine • Opiate • Volatile agents • Propofol • Ketamine

Friesen & Williams (2008)

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Apnea of Prematurity

• Considered pathologic when – Cessation of breathing for > 20 seconds – Cessation of breathing for < 15 seconds

with bradycardia, cyanosis, pallor, or hypotonia

• Central and obstructive, or both


Peiris & Fell (2009).

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Apnea of Prematurity

• Central apnea – diminished response to hypercapnia – ventilatory depression due to hypoxia

• Obstructive apnea – nasal occlusion – occlusion of hypopharyngeal soft tissues

Peiris & Fell (2009)

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Apnea of Prematurity • Underlying problem is immature CNS! • Exacerbated by: – anemia (Hgb < 10 mg/dL) – hypoxia – hypo- or hyperthermia –  intracranial hemorrhage – opioids – ANESTHETIC DRUGS



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What can we do?

• Tactile Stimulation (DO wake the baby!) • Oxygen • Continuous positive airway pressure

(CPAP) • Methylxanthine – caffeine (5-10 mg/kg)

•  Intubation with mechanical ventilation Gregory & Andropoulos (2012)

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Patent Ductus Arteriosus (PDA)

• 50% of full-term infants close PDA within 24 hours

• Gestational age ≥ 30 weeks close PDA within 96 hours

• PDA in younger neonates may remain open • Symptoms appear in 3rd-5th DOL



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Degree of shunting depends on

•  Size of PDA

• Ratio of PVR:SVR RV

LV

í

Andropoulos et al. (2015)

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Anesthesia for an infant with known PDA

•  Large volume IV access • Warming device • Avoid triggers for ductal re-opening

McMann & Soriano (2014)

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Other Problems

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Necrotizing Enterocolitis (NEC)

• NEC primarily affects preterm infants • Age of onset is inversely related to PMA • More than 85% of NEC cases occur in

VLBW or very premature (< 32 weeks) infants

• 10-50% mortality

Sharma & Hudak (2013)

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What causes NEC?

• Inflammatory response • Interaction between milk substrate, microbes, immature immune system – oral feeding – excessive feeding – overgrowth of normal flora

• Hypoperfusion Sharma & Hudak (2013)

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Aggressive feeding

Milk stasis

Intestinal dilation

Inflammation & necrosis

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Signs of NEC • Early signs –  feeding intolerance (vomiting) –  increased work of breathing –  lethargy –  temperature instability

•  Late signs –  hypotension (shock) –  abdominal distention, bloody stool –  apnea –  thrombocytopenia / coagulopathy

Cote et al. (2009,

Gregory & Andropoulos (2012))

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Hypothermia

• High surface area : body weight • ê brown fat stores • Non-keratinized skin

• Flaccid, open posture • Dry gases in the operating room

Peiris&Fell(2009),Gregory&Andropoulos(2012)

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Consequences of Hypothermia

•  Increased metabolic rate • Periodic breathing or apnea • Metabolic acidosis • Hyperglycemia • Delayed drug metabolism

Gregory&Andropoulos(2012),Pani&Panda(2012)

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Measures to conserve heat • Uncomfortably warm operating room (78-86°) • Heat lamps over the bed • Covering the patient with clear plastic • Cap on the head • Forced air warming device • Warming pad on the table • Warmed prep solution


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References •  Peiris K, Fell D. The prematurely born infant and anesthesia. Br J Anaesth. 2009; (9)3:73-77. doi: doi:

10.1093/bjaceaccp/mkp010. Accessed March 7, 2016. •  Hamilton BE, Martin JA, Osterman MJK, Curtin SC, Mathews TJ. National vital statistics reports.

2015; 64(12): 1-64. http://www.cdc.gov/nchs/data/nvsr/nvsr64/nvsr64_12.pdf. Accessed March 7, 2016.

•  CDC Staff. Factors associated with preterm birth. http://www.cdc.gov/reproductivehealth/MaternalInfantHealth/PDF/PretermBirth-Infographic.pdf Accessed March 7, 2016.

•  Gregory GA, Andropoulos DB. Gregory’s pediatric anesthesia. Hoboken, NJ: John Wiley & Sons; 2012.

•  Ballabh P. Intraventricular hemorrhage in premature infants: mechanism of disease. Pediatr Res. 2010; 67(1):1-8. doi: 10.1203/PDR.0b013e3181c1b176. Accessed March 7, 2016.

•  Robinson S. Neonatal posthemorrhagic hydrocephalus from prematurity: pathophysiology and current treatment concepts. J Neurosurg Pediatrics. 2012; 9: 242-258. doi: 10.3171/2011.12.PEDS11136. Accessed March 7, 2016.

•  Ellitt CM, Rosenberg PA. The challenge of understanding cerebral white matter injury in the premature infant. Neuroscience. 2014; 276: 216-238. doi: 10.1016/j.neuroscience.2014.04.038. Accessed March 7, 2016.

•  McMann ME, Soriano SG. Progress in anesthesia and management of the newborn surgical patient. Semin Pediatr Surg. 2014; 23:244-248. doi: 10.1053/j.sempedsurg.2014.09.003. Accessed March 7, 2016.

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References •  Collaco JM et al. Frontiers in pulmonary hypertension in infants and children with bronchopulmonary

dysplasia. Pediatr Pulmonol. 2012; 47:1042-1053. doi: 10.1002/ppul.22609. Accessed March 7, 2016. •  Baraldi E, Filippone M. Chronic lung disease after premature birth. N Engl J Med. 2007;

357:1946-1955. DOI: 10.1056/NEJMra067279. Accessed March 7, 2016. •  Adams JM, Stark AR. Pathogenesis and clinical features of bronchopulmonary dysplasia. UpToDate.

www.uptodate.com. Accessed March 10, 2016. •  Thomas J. Reducing the risk in neonatal anesthesia. Paediatr Anaesth. 2014; 24:106-113. doi:

10.1111/pan.12315. Accessed March 7, 2016. •  Kurth CG, Coté CJ. Postoperative apnea in former premature infants. Anesthesiology. 2015; 123(1):

15-17. http://anesthesiology.pubs.asahp.org/pdfaccess.ashx?url=data/Journals/JASA/934156. Accessed March 10, 2016.

•  Neumann RP, Ungern-Sternberg BS. The neonatal lung – physiology and ventilation. Paediatr Anaesth. 2014; 24:10-21. doi: 10.1111/pan.12280. Accessed March 12, 2016.

•  Andropoulos DB (ed.) Anesthesia for congenital heart disease. Hoboken, NJ: John Wiley & Sons; 2015.

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References •  Sharma R, Hudak ML. A clinical perspective of necrotizing enterocolitis: past, present, and future.

Clin Perinatol. 2013; 40(1):27-51. doi: 10.1016/j.clp.2012.12.012. Accessed March 12, 2016. •  Coté CJ, Kerman J, Todres ID. A practice of anesthesia for infants and children. Philadelphia, PA:

Elsevier. 2009. •  Pani N, Panda CK. Anaesthetic consideration for neonatal surgical emergencies. Indian J Anaesth.

2012; 56(5):463-469. doi: 10.4103/0019-5049.103962. Accessed March 12, 2016. •  Wongprasartsuk P, Stevens J. Cerebral palsy and anaesthesia. Paediatr Anaesth. 2002; 12:296-303.

doi: 10.1046/j.1460-9592.2002.00635.x. Accessed March 12, 2016. •  Petros AJ, Pierce CM. The management of pulmonary hypertension. Paediatr Anaesth. 2006;

16:816-821. doi: 10.1111/j.1460-9592.2006.02014.x. Accessed March 31, 2016. •  Friesen RH, Williams GD. Anesthetic management of children with pulmonary arterial hypertension.

Paediatr Anaesth. 2008; 18:208-216. doi: 10.1111/j.1460-9592.2008.02419.x. Accessed March 31, 2016.

•  Friesen RH et al. Hemodynamic response to ketamine in children with pulmonary hypertension. Paediatr Anaesth. 2016; 26:102-108. doi: 10.1111/pan.12799. Accessed March 31, 2016.


Documents

Part I: Physiology & Pathophysiology - NDANA with Prematurity (Part I).pdf · xxx00.#####.ppt 4/11/16 2:07 PM Patent Ductus Arteriosus (PDA) • 50% of full-term infants close PDA