Principles of Neonatal Surgery (2)

PRINCIPLES OF PRINCIPLES OF NEONATAL SURGERYNEONATAL SURGERY

BY

DR JAMEEL ISMAIL AHMADSURGERY DEPT, AKTH22ND JANUARY, 2008

OUTLINEOUTLINE

INTRODUCTIONINTRODUCTION NEONATAL CONSIDERATIONS NEONATAL CONSIDERATIONS PRE-OPERATIVE CAREPRE-OPERATIVE CARE PEROPERATIVE CAREPEROPERATIVE CARE POSTOPERATIVE CAREPOSTOPERATIVE CARE CURRENT TRENDS CURRENT TRENDS CONCLUSIONCONCLUSION REFERENCESREFERENCES

INTRODUCTIONINTRODUCTION

A neonate is an infant of age 1-28 days Neonates are classified based on

gestational age and birth weight Classification by gestational age

Pre-term- <37 weeks

Term- 37-42 weeks

Post-term- >42 weeks


Classification by birth weight

SGA- <10th percentile

AGA- 10-90th percentile of GA

LGA- >90th percentile of AGA Full term- SGA- <2.5kg

AGA- 2.5-3.5kg

LGA- >3.5kg

INTRODUCTION

Pre-term LBW- 1.5-2kg

VLBW- 1-1.5kg

ELBW- <1kg A normal full term infant has a GA of >37

completed weeks and birth weight of >2.5kg Pre-term is born <37 GA but AGA SGA has birth weight of <10th percentile and

not AGA


Common neonatal surgical conditions GIT-GIT- OA, TOF, Cong. Diaphragmatic hernia, intestinal

atresia, anorectal malformations, Hirschsprung’s disease, Gastroschisis, Omphalocoele, biliary atresia etc

UGSUGS- Hypospadias, Epispadias, Bladder exstrophy, multi/polycystic kidney disease, AEG, undescended testis

CNS-CNS- Hydrocephalus, NTDs MSSMSS- Congenital Hip Dislocation, talipes, sacrococcygeal

teratoma CVS-CVS- Congenital Heart Diseases,COA

ANATOMICAL CONSIDERATIONS OF ANATOMICAL CONSIDERATIONS OF THE NEONATETHE NEONATE

Wider abdomen, broader chest and shallower pelvis

Liver edge is more palpable per abdomen

Urinary bladder is intra abdominal Ribs are horizontal and respiration

almost dependent on diaphragm

PHYSIOLOGICAL NEONATAL PHYSIOLOGICAL NEONATAL CONSIDERATIONSCONSIDERATIONS

A neonate is not a small adult but better considered an immature adult

There many considerations of a surgical neonate which include:

body fluids and electrolytesbody fluids and electrolytes renal functionrenal function cardiovascular functioncardiovascular function respiratory functionrespiratory function thermal controlthermal control Metabolism and nutritionMetabolism and nutrition Immune functionImmune function

BODY FLUID AND ELECTROLYTESBODY FLUID AND ELECTROLYTES

TBW @ birth is 80%, ECF is 45% and ICF is 35% of body weight

In Pre-term it is 84%, 60% and 24% resp The body water is redistributed during the 1st

week through the following phases: pre-diuretic phase- 1st day (1ml/kg/hr) diuretic phase- 2nd-3rd day (7ml/kg/hr) and

natriuresis post-diuretic phase- 4th-5th day

BODY FLUID AND ELECTROLYTESBODY FLUID AND ELECTROLYTES

Fluid administration in early neonatal period should be guided more in Pre-term to prevent overload

Pre-term neonates tolerate fluid restriction more than overload

Sodium regulation is controlled by RAAM which is immature in neonates

Negative Na balance leads to Na retention but in positive Na balance the capacity to excrete Na is poor

RENAL FUNCTIONRENAL FUNCTION 7% of normal neonates may not pass urine in 24hrs Renal handling of water depends on GFR and renal

tubular function GFR is about 25% of adult’s It is function of renal perfusion pressure & renal

vascular resistance which are low and high respectively in the neonate

Tubular urine conc capacity is low with urine osmolality 500-600mosm/kg (cf 1200mosm/kg in adults)

The tubules are relatively insensitive to ADH

CARDIOVASCULAR FUNCTIONCARDIOVASCULAR FUNCTION Fetal circulation undergoes transition to adapt

the extra uterine life Crying and 1st breath leads to lung expansion,

increased O2 tension, decreased pulm artery, increased pulm circulation

Clamping of umbilical cords causes increased systemic artery, LA & LVP which leads to closure of foramen ovale and functional closure of DA

The sphincter closes @ the ductus venosus leading to its closure

BLOOD VOLUMEBLOOD VOLUME

Pre-term- 90ml/kg ~10% body weight Term- 80ml/kg ~7.5% body weight Hb level- 20-22g/dl & haematocrit 60-

65% at birth which decreases as the infant grows

Hb 0f 8g/dl or hct of 30% call for blood transfusion

PULMONARY FUNCTIONPULMONARY FUNCTION

Small and narrow airways- tracheal diameter of 2.5-4mm and can easily be blocked by secretions

Diaphragm is the only muscle of respiration and the sneezing/cough reflexes are absent

Lungs are not fully developed & some alveoli not functional for gas exchange

Tidal volume- 6-10ml/kg and RR up to 60cpm

THERMAL CONTROLTHERMAL CONTROL The mechanism is immature Normal body temp of a neonate is 370c The thermoneutral temp is 32-340c, 28-300c, 30-320c

and 350c for pre-term, term SGA & ELBW neonates respectively

The poor thermal control is due to large BSA/ BW, large BSA/ BW, less subcut fat and thin non-keratinized skin, rich less subcut fat and thin non-keratinized skin, rich surface skin capillaries and poor vasomotor surface skin capillaries and poor vasomotor control, absent sweating & shivering mechanismcontrol, absent sweating & shivering mechanism

Heat loss occur by convection, conduction, evaporation and majorly by radiation

NUTRITION AND METABOLISMNUTRITION AND METABOLISM Small nutritional reserve as main energy source (glucose)

via placenta is cut and then depends on hepatic glycogen store, gluconeogenesis and enteral feeding

All are inadequate in a surgical neonate Total energy requirement in term neonates is

100kcal/kg/day Proteins provide 15% of total calories, carbohydrate & fat

provide 70 and 30% of non-protein calories Prematurity, sepsis, burns increase requirement

NUTRITION AND METABOLISMNUTRITION AND METABOLISM

GLUCOSE Glu control mechanism is immature in neonates and are

predisposed to hypo/ hyperglycaemia Normal blood glucose is 50-60mg/dl (3.33mmol/dl) in

term neonates Hypoglycemia-blood glu <30mg/dl(1.67mmol/dl) in term

and <20mg/dl(<1.1mmol/dl) in LBW may be caused by Low liver glycogen, low gluconeogensis & hyperinsulinism

Prolonged hypoglycaemia leads to seizures & brain damage

Premature neonates, prolonged NPO, diabetic mothers may predispose to hypoglycemia

NUTRITION AND METABOLISMNUTRITION AND METABOLISM

BILURUBIN Physiological jaundice (25-50%) vs. neonatal

jaundice May be due to short RBC life span, immature

hepatic glucoronyl transferase enz or high bilurubin from ABO/ Rh incompatibility, sepsis, G6PD deficiency

Major concern is kernicterus Surgical jaundice- biliary atresia should be

identified to offer early treatment

IMMUNE FUNCTIONIMMUNE FUNCTION

It is immature and are predisposed to infection

Low opsonins: IgA, IgG, IgM, C3b Poor phagocytosis

CONGENITAL ANOMALIESCONGENITAL ANOMALIES neonatal surgery is more or less the surgery of congenital

malformations They are not usually isolated but affect various organ

systems of the body Could be caused by genetic, chromosomal, teratogenic or

unknown causes CNS- Hydrocephalus, NTDs GIT- OA ± TOF, intestinal atresia, ARM, Hirschsprung's

disease Ant abd wall- Omphalocoele, Gastroschisis UGS- PUV, hypo/ epispadias, PKD

PRE-OPERATIVE CAREPRE-OPERATIVE CARE

AIMAIM: to maintain the baby in a physiologically optimal condition for the surgical procedure

RESUSCITATION:- Best done in SCBU Most of our surgical neonates are out born, traveled a long

distance, in bad shape and require resuscitation Ensure good airway by gentle suctioning, O2 & ventilatory

support Fluid,electrolyte & glu mgt-guided and monitored Normal body core temp maintenance NGT for decompression Vital signs monitoring


HISTORYHISTORY GA Antenatal Hx- polyhydramnios, maternal

illness, drug hx Family Hx of congenital anomalies Passage of meconium Micturition Bilious vomiting Abdominal distention


EXAMINATIONEXAMINATION Gen-colour, cry, activity, temp, hydration,

resp distress, apnoea Features of Prematurity abdominal distension, anal orifice CVS examination Detailed other systemic examination to

detect any anomaly

GENERAL CAREGENERAL CARE

RESPIRATORY SYSTEMRESPIRATORY SYSTEM: Ensure patent airway by gentle sterile suctioning Monitor respiratory rate, rhythm and volume Watch for apnoeic attacks and manage Monitor O2 saturation Humidified O2 in incubator or via O2 hood and not

by face mask or nasal catheter NGT-decompression & to prevent vomiting and

aspiration Pulmonary physiotherapy


CARDIOVASCULAR FUNCTIONCARDIOVASCULAR FUNCTION: Fluid loss could occur from vomiting, excessive NGT

aspiration, third space loss and evaporation esp. in anterior abd wall defects and need early replacement

Blood loss may be from birth trauma or haemorrhagic disease

Blood loss should be replaced volume for volume Hb deficit x bw x constant (6,4 & 3 for whole blood,

sedimented or packed cells) Prior to any surgery blood should be grouped and cross

matched

FLUID AND ELECTROLYTESFLUID AND ELECTROLYTES

Fluid and electrolyte derangements usu set in after 24 hours

Mgt is to correct deficit, daily maintenance and replacement of on-going losses and should be strictly according to weight

Fluid requirement first 24hrs- 60-70ml/kg/day 24-48hrs- 70-90ml/kg/day after 48hrs- 100ml/kg/day Na, K and Cl req are 2, 2 & 3 mmols/kg/24hrs

respectively

FLUID AND ELECTROLYTESFLUID AND ELECTROLYTES

50% Ringers lactate(Na-65meq/l and Cl-54meq/l) is the ideal fluid but 4.3% dextrose in 0.18% saline is commonly used

Neonates under radiant heater or phototherapy have higher fluid requirement

Incubators and ventilatory circuits add up to 15-20% of TBW

Monitoring of fluid treatment by input-output chart & vital signs


TEMPRETURE REGULATIONTEMPRETURE REGULATION: Surgical neonates should have neutral core body temp and

kept in a thermoneutral environment Overhead radiant heaters provide more access in case of

emergencies than incubatorsNUTRITIONNUTRITION:: most surgical patients are not on enteral feeding and require

parenteral nutrition commonly via peripheral access TPN is the best in some situations but limited by availability and

cost and the neonate need monitoringBILURUBIN BILURUBIN Hyperbilurubinaemia may require phototheraphy or EBT


RENAL FUNCTIONRENAL FUNCTION Serial measurement of urine output and kidney

function is essential in monitoring fluid mgt Measurement may not be adequate expect where a

urethral catheter is in situCOAGULATION ABNORMALITIESCOAGULATION ABNORMALITIES May be due to hepatic immaturity, low Vit K or

thrombocytopathy Should be sought and managed Parenteral vitamin K should be given DIC may occur and FPP is given


VASCULAR ACCESSVASCULAR ACCESS 24/22G cannular may be used and should be

fixed well to avoid reinsertion Arterial lines may be used for BP monitoring or

blood sampling and CVP lines are for TPN

ANTIBIOTICSANTIBIOTICS Prophylactic or curative and parenteral Empirical Broad spectrum before culture result Group B haemolytic streptococcus and E.coli are the

commonest


INVESTIGATIONSINVESTIGATIONS FBC, U/E/Cr, RBS, Ca, bilurubin, GCM ±Blood gasses, PH, Clotting Profile, Blood

culture Caution and care in amount of blood taken to

avoid CV derangement Micro methods reduces the amount taken

PARENTS COUNSELLINGPARENTS COUNSELLING

TRANSPORTTRANSPORT Prenatal diagnosis allowed in-utero transfer of

surgical neonates to tertiary/specialist centers Post-natal transfers are still the commonest here Before transfer the neonate should be optimised

and accompanied by a paediatritian or Nurse trained in ET intubation and ventilator mgt

Detailed reason for referral and parents counseling are essential

The vehicle should be equipped with life support facilities, IVF & drugs

The neonates should be in incubator or wrapped in thick clothing

TRANSPORTTRANSPORT In gastroschisis and ruptured omphalocoele the exposed

viscus are covered by a plastic sheet wrapped with cotton wool

Most of these are not available and the neonates are transported by their parents after visiting several hospitals ± a referral note

The theatre should be proximal to the SCBU Transfer to or from the theatre should also be in an

incubator or with an overhead radiant heater, wrapped & accompanied by a Doctor or Nurse

IVF & NGT should be maintained

PEROPERATIVE CAREPEROPERATIVE CARE

TIMING OF SURGERYTIMING OF SURGERY: Emergency-surgery mandatory due to life threatening

conditions -OA, CD Hernia, intestinal obstruction, leaking MM,

Gastroschisis, Ruptured omphalocoele, ARM Urgent-surgery done as soon as diagnosis is confirmed -cong hydrocephalus, PDA, sacrococcygeal teratoma, CD

hip, inguinal hernia, AEG, Talipes Elective -Biliary atresia, umbilical hernia, undescended testis, Hypo/

Epispadias, PSARP, Pull through


HYPOTHERMIA PREVENTION & INTRAOP HYPOTHERMIA PREVENTION & INTRAOP MONITORINGMONITORING

Use of thermal mattresses, maintaining a thermoneutral theatre env, radiant heater, warn anaesthetic gasses, IVF, antiseptics and avoiding over wetting during cleaning

Fluid and blood loss monitoring and replacement

Vital signs-HR, BP, Temp, PSO2, ECG ±FBC, U/E/Cr, Blood Gasses, RBS in

prolonged procedures


ANAESTHESIAANAESTHESIA Neonatal anaesthesia now a recognised subspecialty Pre-op preparation and evaluation Fasting ≥3hrs, vit K, NGT decompression, GCM Premedication- Atropine Anaesthetic equipements -breathing system-light, low resistance & dead space (T-

piece system) -ET tube- appropriate length, diametre & uncuffed -straight blade laryngoscope


ANAESTHESIAANAESTHESIA Anaesthetic techniques and agents

-induction-inhalational(O2,N2O2, & volatile agent-halothane, isoflurane)

intravenous-thiopentone, ketamine -maintenance-halothane, isoflurane -neuromuscular blockage-suxamethonium, tubocurare -analgesics-narcotics not used, parenteral paracetamol -reversal-stop inhalational(10mins), neostigmine


OPERATIVE SURGERYOPERATIVE SURGERY Transverse abd incisions preferred Meticulous gentle technique, appropriate instruments

and fine sutures needed Observing general principles of surgery Adequate haemostasis and use of bipolar diathermy Single layer extra mucosal intestinal anastomosis

adequate Stappling devices and endoscopic procedures used Skin closed with single layer absorbable subcuticular

sutures

POSTOPERATIVE CAREPOSTOPERATIVE CARE Neonates recover quicker than adults Monitoring-cont ECG, temp, BP, RR ± blood gasses Analgesia Fluid, electrolyte & input-output chart- maintenance and

replacement Urine output- >1ml/kg/hr suggest good outcome Renal failure managed by kidney challenge or Dialysis Temperature regulation

POSTOPERATIVE CAREPOSTOPERATIVE CARE Identifying and treating hypoglycaemia Hypocalcaemia (<1.5mmol/L) occur in critical neonates in

1st 24-48hrs of life, infant of DM mothers, after large vol transfusion

Post-op haemorrhage- clotting profile, plat to differentiate surgically correctable haemorrhage

Stoma care Long term complications- vit B12 from ileal resection,

incontinence, sexuality, infertility, psychosocial adaptability, malignant potential (undescended testis)

CURRENT TRENDSCURRENT TRENDS

PRENATAL DIAGNOSISPRENATAL DIAGNOSIS USS: in oligo/polyhydramnios, to diagnose abd wall

defects, urinary tract anomalies, intestinal atresia Amniocentesis-USS guided @ 18weeks for karyotyping to

detect inherited/ metab abnormalities Chorionic venous sampling-USS guided @ 8-10weeks for

karyotype,gene probe,enz studies Maternal serum AFP in NTD, duod atresia etc Others: PUBS, MRI Aim: to determine mode of delivery, need for elective

abortion and need for prenatal transfer

CURRENT TRENDSCURRENT TRENDS

FETAL SURGERYFETAL SURGERY 1st open fetal surgery in 1981 @ university of

california Now less invasive procedures eg fetendo and

fetal image guided surgery Procedures include Vesicostomy, CD hernia

closure, excision of sacrococcygeal teratoma, cong heart disease

CONCLUSIONCONCLUSION

Neonatal surgery has developed over the last 4 decades due to better understanding of neonatal physiology and its application to improve surgical outcome

REFERENCESREFERENCES Kulshrestha, R.(2006) Common problems in pediatric

surgery, 2nd edition. CBS publishers and distributors, New Delhi, India

Russell, R.C.G. et al (2004) Bailey & Love’s short practice of Surgery, 24th edition. Edward Arnold Publishers Ltd

Puri, Prem(1996) Newborn Surgery. Butterworth-Heinemann, Oxford

Obianyo, Nene(1996) physiological considerations of the paediatric patient. A lecture

Mohammed A. M. neonatal and paediatric considerations. Undated

Sabiston, D.C. (1997) Sabiston Textbook of Surgery, 15th edition. W.B. Saunders Co. Philadelphia, Pennsylvania

Principles of Neonatal Surgery (2)

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