Intensive care in neonates

Intensive care in neonates

Presenter: Dr PASHIModerator: Dr Bvulani

22/09/16

Introduction • Neonatal intensive care unit (NICU) - specialised care offered to ill or

premature newborn infants• NICU and surgery have helped improve the survival of neonates with

various conditions• These conditions include, but are not limited to, prematurity, low

birthweight, congenital anomalies, and other medical issues

Neonatal Classifications• Neonate : Newborn baby in the first 4 weeks of life• Gestational Age (GA)

Premature - < 37 weeksTerm – 37 to 42 weeksPost term - > 42 weeks

• Weight Vs Gestational AgeSmall for GA – weight lies below the 10th percentile for GAAppropriate for GA – weight lies between 10th and 90th percentileLarge for GA – weight lies above 90th percentile for GA

Neonatal classification ctd• Premature

Moderately low birth weight (82%) – 1501 to 2500gVery low birth weight (12%) – 1001 to 1500g Extremely low birth weight (6%) - < 1000g

• Intrauterine Growth Retardation (IUGR)• Documented decrease in intrauterine growth noted by ultrasonography1. Symmetric IUGR – normal body proportions2. Assymetric IUGR – small abdominal circumference, decreased subcutaneous and abdominal fat, reduced skeletal muscle mass, normal head circumference

Neonatal ProblemsIUGR Preterm

Hypothermia Hypothermia

Hypoglycaemia Respiratory distress syndrome

Polycythaemia Poor oro-motor coordination

Meconium aspiration Patent ductus arteriosus

Jaundice Necrotising enterocolitis

Intraventricular haemorrhage

Neonatal problems ctd Assessment of gestational age can be done

Antenatally – UltrasonographyFirst days after birth – Ballard score (assesses general and physical maturity)

Birth weight and GA – strong indicators of mortality Preterm infants suffer physiologic handicaps

Functional immaturityAnatomic immaturity

Resuscitation at birth• Resuscitation at birth is a relatively frequent occurrence.• Approximately 10% of newborns will require help to establish

breathing at birth, with 1% requiring more extensive resuscitation• Two broad categories identified:

Those who have undergone a period of hypoxic stress in utero, and

those who are prone to hypoxaemia in the immediate postnatal period due to inadequate pulmonary development, airway obstruction or congenital malformations.

Goals of Neonatal Intensive care• Vary depending upon the status of the infant• To return the infant to its normal state of health e.g extremely

premature infants• To find the balance between undertreating and overtreating the

infant e.g. infants with defects or conditions where intensive care may only increase suffering, prolong the act of dying, or result in survival with significant burdens

NICU admission criteria• Admission to NICU should be routine for the following babies:• • Less than 34 weeks• • Less than 1.7kg• • Respiratory distress• • Poor condition at birth requiring resuscitation (consider admission if the cord pH is less than

7.0)• • Congenital abnormalities likely to threaten immediate survival• • Seizures• • Cyanosis• • Sepsis• • Jaundice, requiring intensive phototherapy• • Any other babies where there are substantial concerns

Monitoring• Intensive care unit environment offers continuous monitoring• Monitoring enables assessment of • impact of intensive care unit intervention• characterize the nature and significance of derangements

• Monitoring strategies are designed to follow individual organ function and, to a lesser degree, the interaction between systems.

Parameters Monitored - NICU• Available devices can analyze • physical parameters (pressure, temperature, flow, volume), • electrical function (EEG, ECG, train-of-four), • gas dynamics (saturation, partial pressure), • concentrations (hemoglobin), and • chemistries (microdialysis).

• Monitors are limited in their ability to interrogate tissue health and cellular function.

Monitoring - Interpretation of readings• Measurements should be interpret carefully• considering population norms, • baseline patient capability,• demands of the physiologic circumstance, and tolerance of

deviations from “optimal” or “normal” function

General principles of ICU managementGoals in surgical neonate• Stabilisation• Pre-operative assessment and management to determine ability to

cope with surgery. • While the surgery may be relatively short, its success will depend

upon the calibre of both pre- and post-operative care.

ThermoregulationPrevention of hypothermia • This is well recognised and compensated for in NICU• Transportation vehicles/operating theatres usually not well adapted and

the temperature will need adjustment. • The baby’s core temperature should be maintained at 37°C with

peripheral temperature maintained at 36°C • Thermoneutral temperature – T maintained with minimal metabolic rate• Critical Temperature – metabolic response to cold to replace lost heat• Incubator T determined by Weight and Postnatal age

Thermoregulation - embryology• 5-35 weeks gestation - Hypothalamic function matures• Regulates T control• Regulates pituitary gland hormones

• 20 wks onwards - Brown fat is formed• 23-24wks GA – fetal lung can support gas exchange• 26wks GA - developed keratinised stratum corneum with thin

epidermis• 34 wks GA – epidermal development is complete

Thermoregulation-Heat production• Term baby initiates thermal control at birth• Thermogenesis is initiated by 3 different mechanisms:

1. cutaneous cooling 2. oxygenation3. separation from the placenta

• Non shivering thermogenesis• Brown fat metabolism – primary source of heat • Hepatic glycogenolysis

Thermoregulation-Heat production ctd• The mechanisms of non-shivering thermogenesis include

the metabolism of brown adipose tissue the secretion of noradrenaline and the release of thyroxin

Thermoregulation- inhibitors• Brown fat thermogenesis is inactivated • Vasopressors• Anesthetic agents• Nutritional depletion

• Infants undergoing laparotomy are at increased risk from heat loss directly from exposed bowel.• Aqueous rather than alcohol-based skin preparations - reduce

evaporative heat loss.

Thermoregulation – Heat loss• Heat loss is by

EvaporationConductionConvectionRadiation

Thermoregulation – Heat loss• Surgically ill neonates lose heat by• vomitus,• tachypnoea• when undergoing laparatomy• evisceration at birth (gastroschisis or ruptured exomphalos)

Respiratory system - embryology• Bhutani (2006), lung development can be divided into 7 stages• 5 fetal stages, a neonatal period of approximately 2 months to full

lung development by approximately 8 years• 1. The embryonic stage (0–7 weeks’ gestation)• 2. The pseudoglandular stage (8–16 weeks’ gestation)• 3. The canalicular stage (17–27 weeks’ gestation)• 4. The saccular stage (28–35 weeks’ gestation)• 5. The alveolar stage (>36 weeks’ gestation)

Respiratory system-Surfactant• Produced by the alveolar type II cells

reduce the surface tension in the lungs aiding gaseous exchangeprevents the alveoli from collapsing completely (atelectasis) at the end of expirationHelps to reduce the work of breathing for the infant

• Factors that stimulate synthesisglucocorticoidsCatecholamines also increase surfactant

• Factors that inhibit synthesisInsulinHypothermiaacidosis

Respiratory system at birth• Stimulus of first breath:• Clamping/obstructing the umbilical cord results in an ‘asphyxial’ event• cooling – sudden drop from intra-uterine temperature• physical discomfort from touching and drying

• Neonates : obligatory nasal breathers & obligatory diaphragmatic breathers• Alveoli in the neonatal lung < 10% of the adult quota• new alveoli are continually added up to 8 years of age

Respiratory function• Assessment of respiratory function is a prerequisite for all surgical

neonates as urgent intervention may be required. • Anatomical abnormalities/increasing abdominal distension -

compromise ventilation. • Surfactant deficiency or aspiration pneumonia may contribute• The extent of respiratory support required depends upon clinical and

radiological findings and blood gas analysis

Respiratory support levels• Infants with mild Respiratory Distress Syndrome (RDS)

• with good respiratory effort • and effective ventilationonly require supplemental oxygen to manage their conditionO2 delivered through nasal cannula, via the incubator or a head box or hood

• Infants who display an increase in their work of breathing • associated with hypercarbia• and an increase in oxygen requirements will benefit from increased • reasonable spontaneous respiratory effort with mild hypercarbiaRespiratory support in the form of CPAP

• Infants with decreased respiratory drive or apnoeas with a raised PaCO2 and reduced PaO2 will need to be intubated and ventilated

Respiratory support traumaVentilation in the neonatal period can result in lung injury• increases risk of respiratory morbidity including air leak and chronic lung disease. • Proposed mechanisms for ventilator induced lung injury (VILI):• Volutrauma - alveoli are over-distended by the delivery of too much gas.• Barotrauma - alveoli are subjected to high pressures causing alveolar disruption• Biotrauma due to injurious effects of inflammation, infection and oxidative stress.• Atelectotrauma - alveolar collapse at the end of expiration requiring re-

recruitment with every breath.• Stretch trauma - rate of inflation of the alveoli is beyond their normal elastic

capability.

Respiratory support trauma ctd• The modern trend in ventilating preterm newborns is to provide

the gentlest invasive ventilation possible for the shortest time possible.

allowing permissive hypercarbia and permissive hypoxaemia

Respiratory Support Target readings• Acceptable blood gas results for infants requiring respiratory supportParameter Normal Ventilated preterm infants Term targets Targets with permissive hypercarbia and permissive hypoxia

pH 7.35–7.45 >7.25 7.3–7.4PaCO2 4.5–6 kPa 6–7.5 kPa 4.5–6 kPaArterial PaO2 11–14 kPa 7–12 kPa >8 kPaSaO2 100 per cent 90 per cent >95 per cent

Respiratory support Types1 - Non-invasive – Continuous Positive Airways Pressure (CPAP)• Deliver a predetermined continuous pressure and supplementary oxygen to

the airways of a spontaneously breathing infant (Jones and Deveau 1997)• mechanically splinting the airways open

• Reduce upper airway occlusion and • decreases upper airway resistance

• Improves ventilation • recruiting collapsed alveoli• increasing the surface area available for gas exchange

• Stabilises the chest wall and reduces the work of breathing.

Respiratory support Types ctdCPAP delivery• Nasal CPAP (nCPAP) prongs are the most commonly applied means of

delivering CPAP (Gomella 2004)• Newborn infants are inherent nasal breathers• nCPAP is easily facilitated and well tolerated• Binasal (double) prongs are more widely used than single prongs• Nasal prongs have been associated with erosion• Need to be carefully sized before insertion into the infant’s nares

Respiratory support Types ctd2. Invasive Ventilation• Ventilatory support optimised by monitoring interaction between infant and

ventilator• Allow infant-regulated breath-by breath changes in peak pressures, tidal

volumes, inspiration times and rate• help reduce the ventilator induced lung injury (VILI)

• Types• Continuous mandatory ventilation (CMV)• Volume control (VC)• Assist control ventilation (A/C)• Synchronised intermittent mandatory ventilation (SIMV)

Gastric decompression• Intestinal obstruction and/or sepsis predispose the infant to increased

gastric secretions • Gastric decompression

avoid vomiting and aspiration pneumoniareduce splinting of the diaphragm and aid ventilation.

• Correctly positioned naso-gastric tube large enough to prevent blockage (8fg or greater) • The tip of the tube should be in the stomach and left on continuous

open drainage with gentle intermittent aspiration

Fluid and electrolyte balance• Surgery can exacerbate physiological imbalances in the newborn. • Continuous assessment and monitoring is essential of

perfusion, parenteral fluid and electrolyte requirements and metabolic response to surgical trauma.

• Some infants will need fluid resuscitation pre-operatively – exposed viscera in gastroschisis and examphalos. • Losses via the naso-gastric tube should be measured and replaced

with normal saline with added potassium.

Fluid and electrolyte balance ctd• The stimulus of surgery and intermittent positive-pressure ventilation

(IPPV) lead to increased aldosterone and antidiuretic (ADH) secretion resulting in water and sodium retention.• It may therefore be pertinent to restrict fluid and sodium post-

operatively

Acid Base Balance• Alterations in acid base balance can be caused by several factors.• Respiratory acidosis occurs with inadequate ventilation, for example, in pulmonary

hypoplasia secondary to congenital diaphragmatic hernia.• Metabolic acidosis can occur when

bicarbonate losses are increased poor tissue perfusion, tissue necrosis, infection, hypovolaemia intestinal fistulas and necrotising enterocolitis (NEC).

• The commonest cause in the ‘surgical neonate’ is hypovolaemia which requires fluid replacement for its correction.

• Correction with bicarbonate should be cautious, as it may cause hypocalcaemia (Haycock 2003).

Nutrition• Total parenteral nutrition allows delivery of nutritional substrates

directly into the circulation During prolonged pre-operative stabilisation, conditions predisposing paralytic ileus,

• It promotes anabolism and provides for normal growth and development until gut function is restored.

Nutrition ctd• Glycogen is a skeletal muscle and hepatic storage carbohydrate and is

metabolised when blood glucose falls outside the homeostatic range (Kotoulas et al. 2006). • Neonates have poor glycogen stores due to decreased availability of

substrate in utero, and therefore need a constant glucose intake. • It is essential that dextrose should be administered and the blood

glucose monitored frequently, maintaining a level of 2.6–5.0mmol/L (Nicholl 2003).

Cardiovascular System• A neonate’s blood volume is approximately 80ml/Kg body weight.• A 2kg infant has a circulating volume = average loss during minor adult sgy• Foetal Circulation is associated with (1) the ductus venosus(2) the foramen ovale(3) the ductus arteriosus and including• high resistant pulmonary vascular system due to the collapsed lungs, and a • low-resistance systemic circuit

Cardiovascular System ctd• At birth, haemodynamic changes occur in the transition from fetal to

ex-utero circulation due to • clamping of the placental blood flow and • the expansion of the lung fields

• Cardiac abnormalities can be primary (congenital), maladaptive at birth or acquired (secondary)

Haematological disorders• Coagulation status should be assessed pre-operatively and treated

accordingly.• Assessment should involve those with liver pathologies and suspected

heamoglobinopathies

• The neonate is deficient in vitamin K • May be given either subcutaneously or intramuscularly • In an emergency, it can may given intravenously but close observation will be

required for anaphylaxis (Beers et al. 2006)

Haematological disorders ctd• Neonates with severe sepsis or NEC may develop disseminated

intravascular coagulation (DIC) with associated thrombocytopenia (Puri and Sureed 1996; Stokowski 2006). • Correcting underlying disease process triggering the condition is key• Clotting factors should be replaced by transfusion with appropriate

blood products.

Haematological disorders ctd• Concurrent treatments to control the haemorrhage/clotting cycle include

the administration of • Cryoprecipitate increases Factor VIII and fibrinogen levels• fresh frozen plasma (FFP), FFP can increase coagulation factors by 15–20

per cent • Platelet infusion of 10ml/kg can increase the platelet count by up to

100000/mm3 (Emery 1992; Kenner et al. 1993; Kuehl 1997). • Exchange transfusions may be used to ‘wash out’ any toxins in the infant’s

blood and to replace clotting factors. • Vitamin K may also be given.

Vascular access• A central venous line is highly recommended for prolonged venous

access becauselast longersafely infuse fluids known to have a local irritation or sclerosing

effect.• Peripheral cannulae for administration of medications and blood

product transfusion when necessary. • Arterial access is also helpful to monitor haemodynamic, biochemical

and respiratory status.

Pharmacological support

• There is a risk of sepsis whenever surgery is performed, especially in intra-uterine growth restriction (IUGR) and preterm babies with immature immune systems.• Untreated infection promotes deterioration of the respiratory and

cardiovascular systems and prophylactic antibiotic therapy can reduce this risk. • However, continual review of the course of treatment is essential to

minimise the eventual microbial resistance to antibiotic therapy over time (Kolleff and Fraser 2001).

Pharmacological support ctd• Inotropes are often necessary to improve cardiac function, thus

improving organ perfusion. Dopamine, dobutamine and adrenaline are the most commonly used inotropes in hypotension in neonates.• Pain relief is an important consideration both pre- and post-

operatively.• Cellular damage, particularly in cases of NEC, release pain-producing

substances, augmenting the perception of pain (Brophy 2007).

Anaesthetic effects• Neonates are sensitive to the respiratory depressant effects of opiates

hence require Intubation and ventilation • Effective analgesia via an epidural catheter can be provided without

depressing respiration (Reynolds 2005)• suitable for all surgical procedures below the umbilicus

inguinal herniotomy, Lower limb surgery genito-urinary surgery

Transportation• The critically ill neonate can make several potentially hazardous

journeys from the delivery room to NICU, interhospital referralto and from the operating theatre.

• Safe transportation demands collaboration between a doctor and nurse experienced in neonatal intensive care, and a specialist anaesthetist for the return journey from theatre.• It is suggested that utilisation of specialist staff at this time reduces

‘disasters’ such as aspiration, hypothermia and airway obstruction

Post-operative considerations• Management in the post-operative period mirrors the pre-operative

care in achieving and maintaining physiological stability, but in addition the factors listed below need careful consideration.• Do not leave the operating theatre until the baby is stable. • Doctor and anaesthetist should be in attendance in return journey to NICU• Before returning the baby to the incubator and ventilator, check the settings,

then reconnect fluids and monitor leads to static equipment• Adjust maintenance and arterial line fluids. Commence NG replacement

losses if necessary. Titrate sedation and epidural infusions as appropriate. Observe entry sites• Attach naso-gastric tube to drainage bag

ctd• As soon as possible record:• core temperature then 4-hourly until stable• blood sugar then 1–2-hourly until stable• ventilator settings then 1-hourly until stable• blood pressure continuous read-out, but record hourly• heart/respiratory rate• Attach peripheral temperature probe and maintain temperature above 34°C• Organise a chest X-ray if the baby was intubated in theatre, there is a chest drain

in situ and following diaphragmatic hernia repair• Check blood gas and repeat as necessary

ctd• Record urinary output – attach urine bag or weigh nappies – expect 1ml/kg per hour

after the first 24 hours• Check biochemical and haematological status• Maintain adequate pain relief• Carefully observe wounds, stomas, etc., recording any losses• Tailor endotracheal suction to each individual’s needs – pre-oxygenating if necessary• Encourage parental involvement in care as appropriate• minimal handling is essential to recovery• passive movements and change of position every 4 hours – 6- to 8-hourly care is

adequate

References1. WISCONSIN ASSOCIATION for Perinatal Care, Guidelines for the Responsible Utilization of Neonatal Intensive Care, 19982.A Manual of Neonatal Intensive Care , Fifth Edition, Janet M Rennie, Giles S Kendall, © 2013 CRC Press, Taylor & Francis Group, 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-27423. Admission to the NICU, 2012, Tracey Lawson, Womens Health Maternity Unit, Ashford and St. Peters Hospital NHS trust4. Neonatal Intensive Care Nursing, 2nd Edition, Glenys Boxwell, 2010, by Routledge 2 Park Square, Milton Park, Abingdon, Oxon, OX14 4RN Simultaneously published in the USA and Canada5 IAP color atlas of paediatrics, 2012, Publication of Indian Academy of Pediatrics, Edited by A. Parthasarathy et al, Japee Brothers Medical Publishers(P) Ltd6. Pediatric Surgery Vol.1, Seventh Edition, 2012, Arnold G. Coran et al, Elsevier Saunders