Problem Based Paediatrics The Septic Preterm baby (Sepsis & NEC) Dr Amjad IMAM
The Nurse on the Special Care Unit calls you to review MK, an infant born at 28 weeks, now 10 days old,who was being weaned off ventilation. He now become unwell, desaturating on handling and with temp instability What are your differentials? What do you needs to find out in your history?
What are your differentials? Septicaemia Meningitis Pneumonia Necrotising enterocolitis(NEC) Intraventicular Haemorrhage(IVH) Apnea of prematurity Respiratory distress syndrome(RDS) Patent ductus arteriosus(PDA)
What do you need to find out in your Hx? How & when MK condition changed? Sudden or overtime. Has his ventilatory requirement altered? What feeding regime is he on and is he tolerating feed? Ask about content of nappies!,is there any blood or malaena? Any abdominal distention?any neurological symptoms(Seizure?) Obstetric Hx? Reason of prematurity(multiple gestation,infection,antepartum haemorrhage) Growth retardation? Type of delivery? Did mother received steroids before birth?
MK was born by SVD at 28 weeks gestation after premature labour. Twenty four hour beforeonset of contraction there was a spontaneous rupture of membrane at which time mum was given an I/M injection of steroid. MK was transferred to special baby unit and initially was doing well. However he developed difficulty in breathing and was started on CPAP nia nasal cannulae. This did not help and he was sedated intubated and ventilated. He was given surfactant for presumed RDS and antibiotic for possible infection. Blood culture were sterile. For the last 3 days his ventilation has been improving and the neonatologist were planning a trial of extubation. Today he has had frequent episodes of desaturationto70%&accompanying bradycardia to 60/min. Today he has stopped tolerating his N/G feeds of formula milk and started vomiting. His temp has been upto 38 C and down to 35 C. What features will you look for on examination ?
What feature will you look for on examination? Colour; jaundice , cyanosis, mottling or rash? Examine chest: recession? I/c,,s/c, Crackle or Crepitation? Pulse, BP,perfusion: sign of shock? Assess his hydration? Assess CVS: PDA?bounding pulse,machinery murmer? Feel abdomen: skin tense and shiny?distention? Gaurding? Auscultation for bowl sound, transillumination(Perforation NEC?) CNS: bulging fontanelle? Sing of raised ICP?
MK is clearly unwell. His breathing is rapid and as you watch his oxygen sat. falls to 75%. His abdomen is grossly distended and is tympanic to percussion but does not transilluminate. His nurse tells you that his last nappy contained very dark stools. His temp is 37.8C , Pulse 195, BP 40/20, RR 45, Capillary refill time 4 sec & Oxygen Sat 85% What is your immediate management? What antibiotic therapy will you start? What investigations will you perform?
What is your immediate management? Nill by mouth, TPN Naso gastric tube, decompression of stomach Antibiotics Support circulation. Rx shock Ventilatory support Surgical intervention? What antibiotic therapy will you start? Broad spectrum with anti anaerobe= Pen+Gent+Metro What investigation will you perform? FBC , U&E , Clotting , ABG, Blood culture, Stool occult blood & culture Abdominal X-ray
Some of the MK’sinvestigations are back: Haemoglobin 9.5 g/dl WCC 1.2 10*9/L Platelets 19 10*9/L The abdominal X-Ray showed distended loops of bowel with thickening of the bowel wall, with intramural air and air in the portal tract. How to you interpret these result?
MK’s condition suddenly deteriorate. He becomes more tachycardiac and his ventilation deteriorates and his blood pressure fall . Measurement of his abdominal circumference confirm that the distension has increased . His abdomen now transilluminate. What has happened?
What has happened? MK had NEC with bowl perforation. He requires emergency resuscitation(fluid bolus+ionotropic support+FFP) followed by paediatric surgery referral? He was taken to theatre and partial bowel resection is performed. He was kept on antibiotics+TPN and monitored closely. He was gradually reintroduced enteral feeds.
Definition & Incidence Clinical syndrome of systemic illness accompanied by bacteremia occurring in the first month of life Incidence 1-8/1000 live births 13-27/1000 live births for infants < 1500g Mortality rate is 13-25% Higher rates in premature infants and those with early fulminant disease
Early Onset First 5-7 days of life Usually multisystem fulminant illness with prominent respiratory symptoms (probably due to aspiration of infected amniotic fluid) High mortality rate 5-20% Typically acquired during intrapartum period from maternal genital tract Associated with maternal chorioamnionitis
Late Onset May occur as early as 5 days but is most common after the first week of life Less association with obstetric complications Usually have an identifiable focus Most often meningitis or sepsis Acquired from maternal genital tract or human contact
Nosocomial sepsis Occurs in high-risk newborns Pathogenesis is related to the underlying illness of the infant the flora in the NICU environment invasive monitoring Breaks in the barrier function of the skin and intestine allow for opportunistic infection
Causative organisms Primary sepsis Group B streptococcus Gram-negative enterics (esp. E. coli) Listeria monocytogenes, Staphylococcus, other streptococci (entercocci), anaerobes, H. flu Nosocomial sepsis Varies by nursery Staphylococcus epidermidis, Pseudomonas, Klebsiella, Serratia, Proteus, and yeast are most common
Differential Diagnosis Clinical signs and symptoms are nonspecific Differential diagnosis - NEC RDS Metabolic disease Hematologic disease CNS disease Cardiac disease Other infectious processes (i.e. TORCH)
Clinical presentation Temperature irregularity (high or low) Change in behavior Lethargy, irritability, changes in tone Skin changes Poor perfusion, mottling, cyanosis, pallor, petechiae, rashes, jaundice Feeding problems Intolerance, vomiting, diarrhea, abdominal distension Cardiopulmonary Tachypnea, grunting, flaring, retractions, apnea, tachycardia, hypotension Metabolic Hypo or hyperglycemia, metabolic acidosis
Diagnosis Cultures Blood Confirms sepsis 94% grow by 48 hours of age Urine Don’t need in infants <24 hours old because UTIs are exceedingly rare in this age group CSF Controversial May be useful in clinically ill newborns or those with positive blood cultures
Investigation White blood cell count and differential Neutropenia can be an ominous sign I:T ratio > 0.2 is of good predictive value Serial values can establish a trend Platelet count Late sign and very nonspecific Acute phase reactants CRP rises early, monitor serial values ESR rises late Other tests: bilirubin, glucose, sodium
Radiology CXR Obtain in infants with respiratory symptoms Difficult to distinguish GBS or Listeria pneumonia from uncomplicated RDS Renal ultrasound and/or MCUG in infants with accompanying UTI
Management Antibiotics Primary sepsis: ampicillin and gentamicin Nosocomial sepsis: vancomycin and gentamicin or cefotaxime Change based on culture sensitivities Don’t forget to check levels
Supportive therapy Respiratory Oxygen and ventilation as necessary Cardiovascular Support blood pressure with volume expanders and/or pressors Hematologic Treat DIC with FFP and/or cryo CNS Treat seizures with phenobarbital Watch for signs of SIADH (decreased UOP, hyponatremia) and treat with fluid restriction Metabolic Treat hypoglycemia/hyperglycemia and metabolic acidosis
GBS Prophylaxis GBS is the most common cause of early-onset sepsis 0.8-5.5/1000 live births Fatality rate of 5-15% 10-30% of women are colonized in the vaginal and rectal areas Most mothers are screened at 35-37 weeks gestation
Necrotizing Enterocolitis One of the most serious GI diseases of neonates, especially preterm infants. Intestinal necrosis that can involve all layers of the bowel. Most commonly involves the ileum and colon but can occur anywhere.
Epidemiology Variable incidence Cases often cluster 90-95% of cases are in preterm infants (<34 wks GA) ~10% infants < 1500 grams birth weight (2 – 22%) 1-2% Japan, 7% Austria, 14% Argentina, 28% Hong Kong (VLBW)
Epidemiology Age at onset is inversely related to gestational age Typically occurs in preterm infants at >7 days (2nd to 3rd week of life) 25% of cases occur at > 1 month of age
Enteral feeding NEC occurs almost exclusively after enteral feedings Feeding rate?? Slow careful increases may decrease NEC incidence No difference between slow feeding advances of 15cc/kg/day (13%) and faster advances of 35cc/kg/day (9%) Breast Milk .vs. Formula?? The incidence of NEC is lower in infants fed breast milk versus formula Breast milk increases the diversity of bacterial species colonizing the GI tract of preterm infants
Bacterial colonization ELBW infants (<1000g) have a decreased number of bacterial species colonizing the GI tract Antibiotics decrease the number of bacterial species in the GI tract Preterm infants have a decreased colonization with Bifidobacteria/Lactobacillus which may be protective against NEC
Etiology??? Hypoxemia, acidosis, low cardiac output Splanchnic ischemia hypertonic feedings mucosal edema/ulceration Abnormal gut immunity bacterial colonization Invasive infection of bowel wall Portal system and lymphatics Pneumatosis, portal gas endotoxin release Transmural bowel necrosis Sepsis, DIC, Shock perforation
Surgical Management 30 to 50% of NEC cases will require surgical intervention Bedside drainage (usefull in critically ill infants) Laparotomy Resection (may not do anything for pan-intestinal nec) Ostomy .vs. primary reanastomosis
Complications of NEC Complications occur in about half of infants surviving NEC Strictures (25-35%) Adhesions Abscesses Fistulas Malabsorption Short Bowel Syndrome TPN and central line complications
Outcomes Mortality 10-30% ELBW infants have an increased mortality Increased morbidity in survivors Developmental delay when compared to age-matched controls Increased morbidity secondary to NEC is independent of birth weight, intraventricular hemorrhage or periventricular hemorrhage.