the preterm neonate phm 456 michael heffer bsc phm mhsc l.
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The Preterm Neonate Phm 456 Michael Heffer BSc.Phm.MHSc. What does it mean to be preterm?. Gestational age: age in weeks dated from the first day of the mother’s last menstrual period. Full term: 37-42 weeks Preterm: <37weeks Viability: 23-24 weeks (400-500g). Resuscitation.

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what does it mean to be preterm
What does it mean to be preterm?
  • Gestational age:
    • age in weeks dated from the first day of the mother’s last menstrual period.
  • Full term: 37-42 weeks
  • Preterm: <37weeks
  • Viability: 23-24 weeks (400-500g)
resuscitation
Resuscitation
  • Suction: lungs
  • Intubation
  • CPR:
    • Epinephrine: ETT
  • Establish IV access
    • IV (intravenous)
    • UVC (umbilical venous catheter)
    • UAC (umbilical arterial catheter).
respiratory distress syndrome rds
Respiratory Distress Syndrome (RDS)
  • Primary cause: surfactant deficiency
  • Clinical picture:
    • atelectasis (deflated balloons) hypoxemia, poor lung compliance, alveolar epithelial damage, pulmonary edema.
    • Progresses to fibrous membranes and development of chronic lung disease.
    • Requires high ventilation support: risk of broncho-pulmonary dysplasia.
rds surfactant production
RDSSurfactant production
  • Endogenous cortisol stimulates synthesis at 30-32 weeks in-utero.
  • Normal lung function (34-36wks)
  • Clinical test: amniocentesis
    • Lamellar Body Count: LBC
    • surfactant containing particles in amniotic fluid
    • reflection of lung maturity
rds surfactant production6
RDSSurfactant production
  • Surfactant:
    • synthesized in Type II cells in alveolus.
    • composed of 80-90% lipid DPPC (dipalmitoyl phosphatidylcholine)
    • 10-20% Proteins (spreading action)
    • lowers surface tension in alveolus
    • -stability on expiration.
rds prevention and treatment
RDS Prevention and Treatment
  • Risk of preterm delivery?
    • Betamethasone 6mg x2 dose q24h
    • stimulates surfactant production in the fetus
    • significant reduction in incidence of RDS
  • Multiple courses?
    • MACS study
rds prevention and treatment8
RDS Prevention and Treatment
  • Exogenous surfactant replacement:
  • Synthetic:
    • Exosurf: contains DPPC and spreading agents. No proteins.
  • Natural source:
    • Survanta: minced bovine lung product

contains proteins.

    • BLES: bovine lung exogenous lipid extract- Investigational

Lung lavage. Contains proteins.

apnea of prematurity
Apnea of Prematurity
  • Apnea
    • cessation of breathing for 15-20 seconds.
    • complicated by cyanosis, pallor, hypotonia , bradycardia
  • Nursing scale
    • severity grade 1-4 depending on bradycardia and oxygen required.
    • amount of stimulation required gentle (G) vs vigorous (V) ie. 3G apnea
apnea of prematurity10
Apnea of Prematurity
  • Primary cause: immature systems:
    • decreased sensitivity of chemoreceptors to CO2.
    • diaphragm muscle fatigue
  • Secondary causes: (Rule out)
    • infection
    • low hemoglobin
    • medications (morphine)
    • ventilator related: blocked tube/positioning of infant
apnea of prematurity treatment
Apnea of Prematurity: Treatment
  • Methylxanthines: Caffeine / Theophylline
  • Doxapram infusion(off market-Mar 2001)
  • Mechanism:
    • increased sensitivity of medullary respiratory centre to CO2
    • stimulates central respiratory drive
    • increases diaphragmatic contractility
apnea of prematurity treatment12
Apnea of Prematurity: Treatment
  • Caffeine:
    • longer 1/2 life: 65-100hrs
    • once daily dosing
  • Side Effects:
    • tachycardia, jitteriness
    • rarely seen
    • caffeine levels if symptomatic (40-100 micromoles/L)
  • CAP study: long term effects
neonatal sepsis
Neonatal Sepsis
  • Congenital vs Nosocomial
  • Congenital source:
    • Vaginal flora
    • transplacental (viral infections)
  • Nosocomial ( > 7 days)
    • Environment
    • Instrumentation
neonatal risk factors
Neonatal Risk Factors
  • Low birth weight /preterm
  • Instrumentation:
    • IV lines, intubation changes
  • Immune defense
  • Skin integrity
maternal risk factors
Maternal Risk Factors
  • Prolonged rupture of membranes >24hr
  • Intrapartum fever
  • Peripartum infection:
    • Chorioamnionitis, UTI
  • Group B Strep positive (carrier)
neonatal sepsis16
Neonatal Sepsis
  • Signs: non-specific
    • lethargy, temperature instability
    • poor feeding, poor colour and tone
    • apneas, increased ventilation requirements, increased blood glucose.
neonatal sepsis17
Neonatal Sepsis
  • Full Septic work up
    • Cultures: blood, urine, ETT, swab, LP
    • WBC (white blood cell count) and differential
  • Cultures:
    • Gram stain
    • bacteria: 48hours
    • ureaplasma: 4-5 days
neonatal sepsis18
Neonatal Sepsis
  • WBC (8-34 x109/Litre)
    • trends
    • relative increase
  • Differential:

left shift= immature neutrophils > 0.20(20%)

total neutrophils

immature neutr: bands, metamyelocytes,

neonatal sepsis19
Neonatal Sepsis
  • Treatment: always mg/kg
    • Congenital infection:
    • Prophylaxis: gram +ve and -ve coverage.
    • Ampicillin plus aminoglycoside
    • Nosocomial infection:
    • Prophylaxis: Cloxacillin and aminoglyc.
    • Methicillin (Beta lactamase) resistant?

Switch to vancomycin and aminoglyc.

neonatal sepsis20
Neonatal Sepsis
  • Pharmacist follow up: DRP’s
    • Gram stain,cultures, sensitivities:
    • Coagulase negative staph.

Staph. epidermidis: contaminant?

    • LP positive? 3 weeks treatment
    • consider better penetration: Cefotaxime
    • Therapeutic drug monitoring:
    • gentamicin, vancomycin
patent ductus arteriosus pda
Patent Ductus Arteriosus (PDA)
  • Ductus arteriosus (DA) connects the pulmonary artery and the descending aorta
  • In utero:
    • Output of the right ventricle bypasses the unexpanded lungs by way of the DA and subsequently travels to the placenta for oxygenation
  • Patency of the DA in utero:
    • Maintained through high levels of circulating prostaglandins
pathophysiology
Pathophysiology
  • At birth changes occur in the neonate’s circulation
    • umbilical cord is clamped resulting in an increase in systemic vascular resistance
    • lungs expand and pulmonary vascular resistance drops
    • results in switch from right-to-left shunting across the PDA during fetal life to a left-to-right shunt.
risk with untreated pda
Risk with untreated PDA
  • Increased pulmonary blood volume
    • reduced lung compliance
    • pulmonary hemorrhage
    • chronic lung disease
  • Reduced systemic circulation
    • hypotension/ poor systemic perfusion
    • gut: Necrotizing enterocolitis
    • kidneys: renal failure
    • cerebral ishemia: Intra ventricular hemorrhage
clinical presentation
Clinical Presentation
  • Increased heart rate/tachycardia
  • widened pulse pressure
  • bounding pulses
  • hyperactive precordium
  • continuous murmur
  • Echocardiographic diagnosis
    • diastolic turbulence on Doppler in the pulmonary artery
risk factors for pda
Risk Factors for PDA
  • Premature infants with:
    • Respiratory Distress Syndrome (RDS)
    • Hypoxia
    • Acidosis
    • Fluid Overload
  • incidence of PDA inversely related to the gestational age
  • spontaneous closure occurs more frequently in larger and healthier babies than smaller and sicker babies
pda treatment
PDA Treatment
  • Supportive Measures:
    • fluid restriction (80% of TFI requirements)
    • diuretics to control pulmonary edema if fluid restriction isn’t adequate
    • correction of anemia with transfusions
    • treatment of hypoxia and acidosis
pda treatment indomethacin
PDA treatment: Indomethacin
  • Short course:
    • most commonly used
    • 0.2mg/kg Q12H x 3 doses
    • >20% reopening rates:repeat courses
  • Long course:
    • 0.1mg/kg Q24H x 5-7 doses
  • Best approach not yet determined.
indomethacin side effects
Indomethacin: Side Effects
  •  Renal Function (urine output, creatinine, urea)
    • decreased renal blood flow
  • Necrotizing Enterocolitis (NEC)
    • decreased mesenteric blood flow
  • Hyponatremia
    • water retention
  •  platelet aggregation
    • COX inhibition
  •  bilirubin levels
    • displacement from binding site