In the United Kingdom, such licenses are issued by the Copyright Licensing Agency: Saffron House, 6-10 Kirby Street, London EC1N 8TS. Some tables in the print version of this book are not available for inclusion in the e-book due to copyright.
ESOPHAGUS 385
Professor and Division Chief, Chief of Surgery, Kosair Children's Hospital, Department of Pediatric Surgery, University of Louisville, Louisville, KY, USA. Professor of Hematology, Department of Hematology and Oncology, Our Lady's Children's Hospital, Dublin, Ireland Andrew A StecMD.
GENERAL
DIETRICH KLUTH, WOLFGANG LAMBRECHT, CHRISTOPH BU¨HRER, AND HOLGER TILL
INTRODUCTION
GENERAL REMARKS ON EMBRYOLOGY AND THE EMBRYOLOGY OF MALFORMATIONS
The theory of "bowel rolling" as a step in normal development is a perfect example of this misconception.
DEFINITION OF THE TERM ‘MALFORMATION’
ETIOLOGY OF CONGENITAL MALFORMATIONS
The assumption of multifactorial inheritance stems from the fact that known occurrences have been observed with almost all major disorders.1 In animals, inheritance has also been found for some malformations.2427.
EMBRYOLOGY AND ANIMAL MODELS
EMBRYOLOGY OF MALFORMATIONS
They found that certain parts of the embryo were naturally able to control embryonic development of other parts. Members of the integrin family functionally present as SAMs (adhesion to vitronectin, collagen, fibronectin, complement components or other intercellular matrix proteins) or CAMs (direct adhesion to other cells via corresponding cell surface target molecules).
EMBRYOLOGY OF FOREGUT MALFORMATIONS
However, it is believed that the surrounding mesenchyme may regulate the timing and location of intussusception of the epithelial layer. Incorrect growth of the folds results in the persistence of the primitive tracheo-oesophageal space.
DEVELOPMENT OF THE DIAPHRAGM
This means that delayed or inhibited closure of the pleuro-peritoneal canal cannot result in a diaphragmatic defect of sufficient size. We therefore conclude that the pleuro-peritoneal openings are not precursors to the diaphragmatic defect.
DEVELOPMENT OF THE CLOACA
Shortly after the initiation of the defect in the 14-day embryo, the liver grows through the diaphragmatic defect into the thoracic cavity (Fig. 1.6). In later stages, up to two-thirds of the chest cavity may be occupied by the liver.
HYPOSPADIAS
However, contrary to vdPUTTE,97, we think that a lower growth of the urorectal fold occurs, although it is probably not responsible for the formation of cloacal malformations. Cloacal malformations are caused by improper development of early cloacal membrane attenuation as shown in SD mouse embryos.98,99.
CONCLUSION
Fiegel HC, Rolle U, Metzger et al. Testicular descent in the rat: a scanning electron microscope study. Pediatr Surg Int. Ekesparre Met al. Natural history of congenital diaphragmatic hernia and pulmonary hypoplasia in the fetus. J Pediatr Surg.
CARLOS E BLANCO, EDUARDO VILLAMOR, AND LUC JI ZIMMERMANN
FETAL BREATHING MOVEMENTS
This focused attention on the upper pons in the inhibition of fetal breathing movements. Direct confirmation of this idea came from the study of Johnston and Gluckman,24 who performed a two-step procedure: first, lesions were placed as before in the brainstem to prevent inhibition of the FBM by hypoxia or to provide an overt stimulation; .
PERIPHERAL CHEMORECEPTOR FUNCTION IN UTERO
The work of Barcroft20 gave rise to the concept that inhibitory mechanisms originating from higher centers are involved in producing apneic periods in the fetus. These studies were extended by Dawes and colleagues22, who used the technique for transection in the chronically instrumented late gestation fetal sheep.
PHARMACOLOGICAL CONTROL
First, it was clear that the peripheral chemoreceptors would be able to stimulate fetal breathing under some circumstances, but that it was the balance between this stimulatory input and the normally dominant, inhibitory input from higher centers that determined the characteristics of fetal breathing . Second, it redirected attention to the role of the carotid chemoreceptors in initiating cardiovascular reflex responses to hypoxia.32,33 Finally, the observation that the fetal peripheral chemoreceptors discharge spontaneously (at about 5 Hz) at the normal fetal arterial PO2, of course. that the rise in PO2 at birth would silence them.
LUNG GROWTH ASSOCIATED WITH FETAL BREATHING MOVEMENTS
Both carotid30 and aortic31 chemoreceptors were found to be spontaneously active at normal arterial PO2 in fetal sheep and to respond with an increase in discharge as PO2 falls or PCO2 rises. Their sensitivity to PO2 would then have to return postnatally to the adult range, and this has generated research into the mechanisms of this reset.34,35.
CHANGES AT BIRTH
POSTNATAL BREATHING
In addition, the brainstem reticular formation and related nuclei associated with sleep and arousal have not been much studied in the postnatal period. The locus coeruleus has been implicated in causing arousal at birth.90 There are also reports that structures as high up in the brain as the thalamus are involved in the descending inhibition of breathing during hypoxia.91.
THE FETAL CIRCULATION AND ITS TRANSITION AT BIRTH
In summary, spontaneous breathing movements are present during fetal life and are important for normal fetal lung development. However, breathing remains associated with behavioral and sleep states in the newborn as in the fetus, and there is clearly continuity in some control processes from late pregnancy to early postnatal life.
CLOSURE OF THE DUCTUS VENOSUS
Although the ductus venosus has received less attention than the DA, it is now well accepted that it plays an important role in the regulation of fetal circulation. However, in almost all neonates, the ductus venosus remains patent for some time after birth with significant variations in the volume of blood flow.112 Closure of the ductus venosus is more delayed in premature infants, and a patent ductus venosus appears to be related to changes in ammonia detoxification, blood clotting and regulation of total bile acid serum concentration.112.
CLOSURE OF THE FORAMEN OVALE
The PO2 of the blood supplying the heart, brain, head, and neck is 45 mmHg higher than that of the blood in the descending aorta. Vessel entry is under active control, and a compensatory mechanism, supported by transient dilation, is assumed to increase the flow of oxygenated blood through the ductus venosus during hypoxia or reduced umbilical flow.110 Absence of the ductus venosus is associated with a high incidence of fetal anomalies. and adverse outcomes, including associated malformations, chromosomal aberrations, heart failure in utero, and absent portal vein.111 Functional closure of the ductus venosus, which is followed by anatomical closure, is nearly complete within weeks of birth.
FALL IN PULMONARY VASCULAR RESISTANCE
A large portion of the inferior vena cava that returns passes through the foramen ovale into the left atrium into the left ventricle and is thus distributed to the coronary and cerebral circulations.
CLOSURE OF THE DUCTUS ARTERIOSUS
Several events promote DA constriction in the term neonate: (1) increase in arterial PO2, (2) decrease in ductal lumen blood pressure (due to postnatal reduction in PVR), (3) decrease in circulating PGE2 (due to loss of placental prostaglandin production and increased prostaglandin clearance with the lungs), as well as a decrease in the number of PGE2 receptors in the wall of the ductus. The timing of DA closure after birth varies between species, but in humans it is usually completed within 48 hours.129 In the full-term infant, DA closure at birth occurs in two phases. Constriction causes ischemic hypoxia of the vessel wall, this hypoxia suppresses the local production of PGE2 and NO and induces the formation of growth factors.
LUNG DEVELOPMENT: STRUCTURAL DEVELOPMENT, SURFACTANT, AND
Wallen LD, Murai DT, Clyman RI et al. Regulation of breathing movements in fetal sheep by prostaglandin E2.J Appl Physiol. Wallen LD, Murai DT, Clyman RI et al. Effects of meclofenamate on breathing movements in fetal sheep before delivery. J Appl Physiol.
MARK D STRINGER
GROWTH AND PROPORTIONS
CARDIOVASCULAR SYSTEM Circulatory changes after birth
In adults, the remaining ligamentum venosum passes within the fissure that separates the anatomical left lobe of the liver and the caudate lobe. Ventriculoseptal defects are the most common, more often affecting the membranous part than the muscular part of the interventricular septum.
RESPIRATORY SYSTEM Upper airway
In the newborn, the femoral artery can be felt halfway between the anterior superior iliac spine and the pubic tubercle; it is therefore more lateral than in the adult, where the surface marker lies halfway between the anterior superior iliac spine and the pubic symphysis.3 The renal arteries are located at a higher vertebral level in the neonate (T12L1) compared to the adult (upper limit of L2)3 and the aortic branch is at the superior rather than inferior border of L4. The gland overlies the trachea, major blood vessels (especially the left brachiocephalic vein), and the upper anterior surface of the heart.
ABDOMINAL WALL AND GASTROINTESTINAL TRACT
The right main bronchus is wider and steeper than the left and the carina is more likely to lie to the left of the midline. The tip of the newborn spleen is often palpable just below the left costal margin.
GENITOURINARY SYSTEM
The timing and process of closure of the vaginal process are both uncertain.35 Surgical studies have shown that a patent vaginal process is present in approximately 60% of contralateral inguinal explorations in infants with a unilateral inguinal hernia in the first two months, decreasing to approximately 40%. % after two years. Of the seven million eggs estimated to be present in the female fetus, only one million remain at birth, and this number decreases further to about 40,000 at puberty.
MUSCULOSKELETAL SYSTEM Skull and face
Almost one-third of the neonatal femoral head extends outside the acetabulum, making it easier to dislocate the hip joint. Developmental dysplasia of the hip affects about one in 100 live births and is more common in girls.
NERVOUS SYSTEM
The termination of the spinal cord in the neonate may reach as low as L3, while it is usually around the lower border of L1 in the adult. The supracristal level between the tops of the iliac crests is slightly higher (L3/4 rather than L4).
SKIN AND SUBCUTANEOUS TISSUE
Myelination is at its peak in the first six months of life, but continues until maturity.3 The distribution of sulci and gyri at birth is similar to that of the adult, although the central sulcus is slightly more anterior and the ventricles are relatively larger.
ACKNOWLEDGMENTS
A new concept of the anatomy of the anal sphincter mechanism and the physiology of defecation.
EDWIN C JESUDASON
BIRTH DEFECTS HELPED DEFINE PEDIATRIC SURGERY
BIRTH DEFECTS ARE LEADING CAUSES OF GLOBAL INFANT MORTALITY
BIRTH DEFECTS EPIDEMIOLOGY AND TERATOLOGY EMERGED FROM OUTBREAK
It can now be said that such monitoring of birth defects serves a range of important purposes, including early warning of outbreaks, identification of possible environmental or genetic causes, rational planning for neonatal surgical facilities, facilitation of antenatal counseling based on accurate data, setting up of associations. between birth defects (which guide management and provide clues to the underlying developmental biology) and the comparison of outcomes (which therefore guide us to best practice).9.
CAUSATION OF BIRTH DEFECTS REMAINS OFTEN COMPLEX AND UNCERTAIN
BIRTH DEFECTS APPEAR TO ARISE TYPICALLY (BUT NOT EXCLUSIVELY) IN THE FIRST
TRIMESTER
Exomphalos is considered an embryonic lesion accompanied by concomitant lesions of organogenesis in other systems such as the heart. An alternative view is that intestinal atresias are rarely the result of fetal accidents such as intussusception and are actually better understood as failures in the development of the mesenteric vasculature.25 A similar contrast between duodenal atresia and small intestinal atresia can also be understood as the result of their different beginnings and etiology.
CLASSIFICATION OF BIRTH DEFECTS FOR EPIDEMIOLOGICAL PURPOSES
Gastroschisis and intestinal atresia can be considered in this latter category.2224 Indeed, the contrast between exomphalos and gastroschisis in terms of associated anomalies (and therefore prognosis) can be considered due to the different times they are usually considered in development. In contrast, like associated intestinal atresias, gastroschisis is thought to result from a discrete fetal vascular accident and thus lack extraintestinal manifestations.
COUNTING OF BIRTH DEFECTS IS AFFECTED BY THE DEFINITION OF STILLBIRTH
Similarly, several other registries feed the birth defect surveillance data provided by the World Health Organization (WHO). Recent articles in the British Medical Journal reinforce the logistical shortcomings of birth defect reporting in Britain.38.
PEDIATRIC SURGEONS OFTEN REPORT INSTITUTIONAL SERIES OF BIRTH DEFECTS
Their Birth Defects Atlas is an interesting publication available in the public domain (www.who.int/genomics/publications/en/). The interpretation issues raised not only highlight the issues discussed in the previous sections, but also point to the ongoing challenge of inadequate resources and expertise for reporting birth defects.
THE CHALLENGE FOR MODERN PEDIATRIC SURGERY
Hansen M, Kurinczuk JJ, Bower Cet al. Risk of major birth defects after intracytoplasmic sperm injection and in vitro fertilization. N Engl J Med. Lin AE, Forrester MB, Cunniff Cet al. Clinical screeners in birth defect surveillance programs: A survey of the National Birth Defect Prevention Network.
TIPPI C MACKENZIE AND N SCOTT ADZICK
ULTRASOUND
MAGNETIC RESONANCE IMAGING
AMNIOCENTESIS
CHORIONIC VILLUS SAMPLING
BIOCHEMICAL MARKERS
PERCUTANEOUS UMBILICAL BLOOD SAMPLING
FETAL CELLS IN THE MATERNAL CIRCULATION
Therefore, invasive testing remains the standard of care for the prenatal diagnosis of aneuploidies and other genetic abnormalities.
PRENATAL DIAGNOSIS OF SPECIFIC SURGICAL LESIONS
Ultrafast fetal MRI is superior,37,38 as it can determine the intrapelvic dimensions of the tumor as well as the presence of bleeding (Fig. 5.2). Prenatal interventions for SCT include cyst aspiration (for those with a predominant cystic component), amniotic fluid reduction (for those with severe, symptomatic polyhydramnios with an amniotic fluid index (AFI) of 35), amniotic fluid infusion (for those with bladder outlet obstruction, to facilitate placement of a vesioamniotic shunt) or open fetal surgery for resection of the mass.
CONGENITAL CHEST LESIONS
The volume of the CCAM compared to the head circumference (CCAM volume ratio, CVR) is an important prognostic indicator: fetuses with a CVR greater than 1.6 are more likely to develop hydrops.60. The degree of pulmonary hypoplasia is proportional to the time of herniation, the size of the diaphragm defect, and the amount of viscera herniated.
GASTROINTESTINAL LESIONS Esophageal and bowel atresias
The strategy for treating in utero CDH has undergone many changes over the past two decades, with the current approach involving tracheal occlusion using a percutaneous fetoscopically deployed balloon (FETO) and subsequent reversal of the occlusion prior to delivery (reviewed in refs 87 and 88). The basis for this approach is the recognition that fetal tracheal occlusion leads to compensatory lung growth due to a decrease in fluid outflow from the lungs, as confirmed in lamb models of CDH.89 Given the embryology of lung growth, occlusion earlier in pregnancy, before the pseudoglandular stage of lung development, may lead to more reliable lung growth.
ABDOMINAL WALL DEFECTS
Moreover, the timing of delivery has been an unanswered question: the urgency to prevent in utero intestinal damage must be tempered with the risks of prematurity in these infants, many of whom are small for gestational age. Whether cesarean delivery would protect the exposed bowel from further damage during delivery has been considered, but does not appear to confer any benefit on outcome.113,114 Thus, the mode of delivery for.
PRENATAL DIAGNOSIS OF RENAL ANOMALIES
Ultrasound features such as bowel dilatation, bowel wall thickening, and mesenteric flow have been studied by many groups as potential prognostic indicators. Interestingly, prenatal ultrasound findings did not predict postpartum course for any of the parameters examined (simple vs. complex, primary vs. silo, length of hospital stay, time to enteral feeding, etc.).
UPPER URINARY TRACT OBSTRUCTION
LOWER URINARY TRACT OBSTRUCTION
MYELOMENINGOCELE
Analysis of the potential benefits of fetal repair of MMC has been performed in ovine models of the defect,139141, providing a compelling rationale for uterine repair, the first non-fatal disease to be considered for this treatment. We reported the first open repair of fetal MMC leading to improved neurological outcome and resolution of the ArnoldChiari malformation (Fig. 5.9).
CONCLUSIONS
Mackenzie TC, Crombleholme TM, Johnson MPet al. Natural history of prenatally diagnosed conjoined twins. J Pediatr Surg. Hubbard AM, Crombleholme TM, Adzick NSet al. Prenatal MRI evaluation of congenital diaphragmatic hernia. Am J Perinatol.
KOKILA LAKHOO
CONGENITAL MALFORMATION
PRENATAL DIAGNOSIS
High-risk pregnancies may be offered further invasive diagnostic investigations such as amniocentesis or chorionic villous sampling (CVS). Structural abnormalities that are difficult to define on ultrasound, such as hindbrain lesions, or in the presence of oligohydramnios, are better imaged on ultrafast magnetic resonance imaging.
SPECIFIC SURGICAL CONDITIONS Congenital diaphragmatic hernia
Lakasing L, Cicero S, Davenport M et al. Current outcome of prenatally diagnosed exomphals: an 11-year review. J Pediatr Surg. Chisholm CA, Heider AL, Kuller JA et al. Prenatal diagnosis and perinatal management of fetal sacrococcygeal teratoma. Am J Perinatol.
PREM PURI AND PIOTR HAJDUK
FETAL TRAUMA
BIRTH TRAUMA
Rupture of the spleen in the newborn is much less frequent than rupture of the liver. Ultrasound: a new approach to the diagnosis of adrenal hemorrhage of the newborn. J Can Assoc Radiol.
PREM PURI AND RESHMA DOODNATH
PRENATAL TRANSFER
PRE-TRANSFER MANAGEMENT
All laboratory reports should be included and the time the tests were performed noted. Where possible, a cord blood sample should be sent, along with a copy of the mother's records, including the mother's full history, labor and delivery records.
TRANSPORT TEAM
If there is a risk of deterioration of spontaneous breathing, the child should be intubated before departure5, as emergency intubation during travel is often difficult or dangerous. Except for patients with a fractured skull base, nasal obstruction, or significant coagulopathy, every child should be intubated nasotracheally.13 All intubated patients should be suctioned regularly/hourly.
TRANSPORT VEHICLES
The consent of the parents for the operation, signed by the mother, if the parents are not married, must be sent together with the contact telephone number, so that the surgical condition of the child and the operation can be explained to the parents. The set of equipment must be checked weekly by the nurse on duty for neonatal transport, the transport incubator and monitoring equipment must be serviced. 10.
TRANSPORT INCUBATORS
This is especially important when establishing pneumothoraces, pneumoperitoneum or intramural gas.18 It is therefore important to ensure that all air leaks are evacuated if possible. All monitors and syringe pumps should be battery powered.6 A range of airway and breathing equipment including self-inflating resuscitation bags, masks, airways, laryngoscope handles and blades, cuffed neonatal endotracheal tubes of various sizes, humidifiers, portable suction equipment and oxygen supplies should be available for in case respiratory problems arise.
TRANSPORT PROCEDURE
The negative effects of altitude on the newborn's body can be harmful.19 As altitude increases, the partial pressure of oxygen decreases, making the diffusion of oxygen across the alveolar membranes more difficult, resulting in decreasing oxygen saturation in the infant. It is also very important to have properly functioning medical and nursing equipment in case this emergency occurs.10 Monitoring is essential during transfer as clinical assessment may be limited due to suboptimal lighting, noise, vibration and lack of space.
RECEIVING CENTER
It contains all the necessary medical and practical details regarding the actual transfer and specific management of the surgical problem of the newborn.
SPECIAL CONSIDERATIONS Gastroschisis
Therefore, the tip of the endotracheal tube should be placed proximal to the carina but distal to the fistula. A nasogastric tube should be placed immediately after diagnosis to decompress the gastrointestinal tract and prevent further lung compression.
PREM PURI AND JOHN GILLICK
HISTORY AND PHYSICAL EXAMINATION
Although the body weight of the SGA child is low, the body length and head circumference approximate those of a child of normal weight for age. The number of anatomical malformations in infants with LBW is higher than in full-term infants.17
MAINTENANCE OF BODY TEMPERATURE
RESPIRATORY FUNCTION
An opaque nasogastric tube in the stomach has an important role in both diagnosis and treatment. Surfactant replacement is commonly used in the clinical treatment of neonates with respiratory distress syndrome (RDS).
CARDIOVASCULAR STATUS
It is important to recognize that more than one condition may be present in the same patient. All infants with respiratory distress should have an opaque nasogastric tube and an X-ray including the chest and abdomen to localize the esophagus, stomach, and intestinal gases and to avoid misdiagnosis of, for example, diaphragmatic hernia. which may be confused with an adenomatoid cystic malformation of the lung.24 Blood gas studies are essential in the diagnosis and management of respiratory distress.
METABOLIC STATUS Acid base balance
When the serum bilirubin concentration approaches a level where kernicterus is likely to occur, hyperbilirubinemia should be treated. The infant's gestational age must be considered, as kernicterus may occur in the absence of profound hyperbilirubinemia in premature infants.
COAGULATION ABNORMALITIES
Hyperbilirubinemia in the newborn may have a pathological basis, such as severe sepsis, Rh and ABO incompatibilities, and congenital hemolytic anemias. When serum indirect bilirubin rises early and rapidly above 340 mmol/L, hemolysis is usually the cause and exchange transfusion is indicated.
LABORATORY INVESTIGATIONS
If there is no response to correction of calcium deficiency, a serum magnesium level should be obtained. Jaundice in the newborn is a common physiological problem that is seen in 2550% of all normal newborns and in a significantly higher percentage of premature and SGA babies.43 This is the result of a combination of shortened red cell survival, with a consequent increase in bilirubin load, and an immature glucuronyl transferase enzyme system with a limited capacity to conjugate bilirubin.
VASCULAR ACCESS
This central line is often mandatory and a basic monitoring device for the anesthesiologist at the time of surgery and can sometimes be performed in theater immediately before surgery begins. Critically ill neonates will require an arterial line, particularly at the time of surgery, either because of the surgery when it is expected to result in significant fluid shift and hemodynamic instability, or because of significant underlying cardiopulmonary disease in the neonate.
FLUID AND ELECTROLYTES, AND METABOLIC RESPONSES
Intravascular volume adequacy and cardiac function can be assessed by a central venous catheter (CVC), which can be inserted through the umbilical vein, internal jugular vein, subclavian and femoral veins. These include the infant's environment (ambient humidity and ambient temperature22), metabolic rate, 59 respiratory rate, gestational maturity, body size, surface area, fever, and use of radiant heaters and phototherapy.60 In infants weighing less than 1500 g at birth, insensible loss may be up to three times greater than that estimated for term infants.61 Fanaroff and colleagues found insensible water loss in infants weighing less than 1250 g to be 60–120 mL/kg. per day.62 The leading factor among the factors influencing insensitivity. Water loss is the gestational age of the infant and the relative humidity of the environment.63 It has recently been reported that application of a semipermeable polyurethane membrane ('Tegaderm') to the skin of extremely LBW infants immediately after birth decreased fluid and electrolytes after birth. concerns and significantly improved their outcome by decreasing the severity of lung disease and decreasing mortality.64.
RENAL FUNCTION, URINE VOLUME AND CONCENTRATION IN THE NEWBORN
Respiratory water loss is approximately 5 ml/kg per 24 hours and is negligible when infants are intubated and on a ventilator. Water loss through sweat is generally negligible in the newborn, except in patients with cystic fibrosis, severe congestive heart failure, or high ambient temperature.
SERUM ELECTROLYTES AND METABOLIC RESPONSES IN NEONATAL SURGICAL
PREOPERATIVE MANAGEMENT OF VARIOUS SURGICAL NEONATAL CONDITIONS
In the presence of severe enterocolitis due to obstruction, with associated large fluid losses in the intestine, adequate preoperative fluid replacement is mandatory to ensure a reasonable outcome. Preoperative treatment of patients with gastric outlet obstruction includes fluid replacement and at least potential correction of the hypochloremic alkalosis by infusion of chloride and potassium chloride (Table 9.4).
FLUID MANAGEMENT PROGRAM
The role of extracorporeal membrane oxygenation in the management of infants with congenital diaphragmatic hernia. Semin Perinatol. Value and limitations of auscultation in the management of congenital heart disease. Pediatr Clin North Am.
DECLAN WARDE AND NICHOLAS EUSTACE
PREOPERATIVE PREPARATION AND EVALUATION
If it is anticipated that multiple vascular access routes will be required (e.g., for central venous pressure or direct arterial pressure monitoring), it may be advisable to establish these in the intensive care unit (ICU) before transferring to the operating room. usually easier to maintain a child's body temperature in the intensive care environment. If transfer to the operating room is considered unacceptably dangerous, for example in the case of some extremely ill, low birth weight infants, it may be advantageous to undergo surgery in the ICU itself.1,2.
TRANSFER TO THE OPERATING THEATER
Preoperative hemoglobin level should be at least 12 g/dL; if lower, consideration should be given to transfusion of packed red blood cells before anesthesia and surgery. Atropine is the most commonly used drug, usually at a dose of 0.02 mg/kg by intravenous (i.v.) injection immediately before induction of anesthesia.
OPERATING THEATER AND ANESTHETIC EQUIPMENT
A suitable temperature-controlled humidifier should be incorporated into the inspiratory side of the ventilator circuit. The ability to deliver air/oxygen mixtures through the ventilator or anesthesia circuit must be available.
CHOICE OF ANESTHETIC AGENT AND TECHNIQUE
TUBOCURARINE AND PANCURONIUM
ANALGESIA
They may be particularly valuable in high-risk infants.6165 A recently described transverses abdominis plane (TAP) block has been used to provide analgesia following pyloromyotomy surgery.66. In the newborn, this structure is long and lax and must be moved anteriorly from posteriorly to facilitate visualization of the larynx.
MAINTENANCE OF ANESTHESIA
There was no significant difference in total morphine consumption between paracetamol and placebo groups.58 Codeine has been used for many years in the treatment of mild to moderate pain. It is difficult to manipulate Magill forceps in the mouth of a small child, but bending the neck usually facilitates the passage of the nasotracheal tubes.
REVERSAL AND EXTUBATION
However, protocols for its use in infants and children are not well documented in the literature.59 Non-steroidal anti-inflammatory drugs are not widely used for analgesia in infants.60. Once intubation is achieved, both lungs should be carefully auscultated to check for equal air entry and the endotracheal tube should be securely fixed.
MONITORING
If it is considered at the time of induction of anesthesia that postoperative mechanical ventilation will be required, the tube should be inserted through the nose rather than through the ears. Due to the problems associated with hyperglycemic states in childhood and hyponatremia, caution should be exercised when using 10% dextrose infusions.70,71 It is important to take the volume into account when calculating the fluid of the drug diluents administered during anesthesia and surgery. balance.
ANESTHESIA FOR SPECIFIC SURGICAL CONDITIONS
Positive pressure ventilation using bag and mask should be avoided before endotracheal intubation, as expansion of the viscera contained in the hernia will cause further lung compression. To maintain oncotic plasma pressure, at least 25% of fluid intake should be given as colloid.
SPECIAL CONSIDERATIONS FOR THE PREMATURE INFANT
Acceleromyography in neonates and young infants: baseline calibration and recovery of responses after neuromuscular blockade with rocuronium. A survey of members of the Association of Pediatric Anesthetists of Great Britain and Ireland. Pediatr Anesth.
DESMOND BOHN
RESPIRATORY MANAGEMENT
POSITIVE PRESSURE VENTILATION
The microprocessor controls the inspiratory valve, which, when opened, delivers heated humidified gas to the patient. The microprocessor also controls the exhalation valve, which opens during exhalation and the filtered gas is vented to the atmosphere.
PRESSURE PRESET VENTILATION
Ventilator technology has improved significantly in the past 20 years, and currently available machines are sufficiently adaptable to ventilate adults and children, including infants. In the young child, the endotracheal tube (ET) is the site of greatest resistance in the circuit.
VOLUME PRESET VENTILATION
PATIENT-TRIGGERED VENTILATION AND SYNCHRONIZED VENTILATION
WEANING FROM VENTILATION
CONTINUOUS POSITIVE AIRWAY PRESSURE AND NONINVASIVE VENTILATION
The system has proven effective in the treatment of lung disease of prematurity as a primary method of therapy. The widespread use of CPAP in lung disease of prematurity is in fact the rediscovery of an old technique first described by Gregory in 1971 for the treatment of this condition. proven effective in the treatment of lung disease of premature infants as well as a primary method of therapy and as a method to prevent extubation failure in premature infants.410.
ALTERNATIVE (NONCONVENTIONAL) MODES OF VENTILATION
Although HFJV and HFOV work on the same physiological principles of very small tidal volumes delivered at high rates, they should not be viewed as just two variations on the same theme. Although HFJV and HFOV operate on the same physiological principles of very small tidal volumes delivered at high speed, they should not be regarded as just two variations on the same theme.
RESPIRATORY GAS EXCHANGE Carbon dioxide elimination
The mortality reduction effect associated with the widespread use of surfactant replacement therapy in this disease over the same period meant that clinical trials of HFV compared with CMV were unable to demonstrate any survival benefit. The same can be said for clinical trials that use the incidence of chronic lung disease as their end point. 28 , 29 On the other hand, case series have suggested improved outcomes when used in rescue mode in term and near-term infants with CDH, meconium aspiration, and bronchopleural fistula.
HYPERVENTILATION AND VENTILATOR- ASSOCIATED LUNG INJURY
Pulmonary abnormalities that cause a large difference between PAO2 and PaO2(A-a DO2) can also be compensated for by increasing FiO2. The choice of options for ventilatory management of a newborn largely depends on the patient's condition.
RESPIRATORY MONITORING Blood gas measurement
Greater accuracy is achieved by careful maintenance of the probes and care in calibration and application to the skin. PetCO2 provides useful information about the adequacy of alveolar ventilation in patients with normal lungs, but the PaCO2PetCO2 gradient widens in the presence of lung disease.
MANAGEMENT OF THE INTUBATED PATIENT Tube size and position
The presence of excessively thick secretions in the airways should alert one to the possibility of inadequate humidification. There is therefore less cooling of the gases in the breathing tubes and the inhaled gas is fully saturated and delivered to the ET tube at a temperature of 378°C.
ACUTE HYPOXIC RESPIRATORY FAILURE IN THE NEWBORN: NONVENTILATOR THERAPIES
The tip of the catheter can be induced to pass down either side by rotating the head to the opposite side. The goal of optimal humidity is to deliver fully saturated gases (44 mg/L H2O) at a temperature of 378 C to the apex of the airway.
SURFACTANT REPLACEMENT THERAPY
Too much humidification leads to 'rainout' as the inhaled gas cools during the passage between the humidifier and the child's airways, which can lead to the absorption of significant amounts of water. This can only be achieved with a heated water bath humidifier, as opposed to the nebulizer type.
VENTILATOR MANAGEMENT OF CONGENITAL DIAPHRAGMATIC HERNIA
Surfactant, used prophylactically in patients at risk of or with established early lung disease, resulted in a reduction in mortality and the incidence of air leakage, but did not have a major impact on the incidence of chronic lung disease. .60 This may be because it was not used with an optimal ventilation strategy that minimizes ongoing lung damage. Human studies have shown that the use of surfactant replacement therapy in this patient population is associated with a reduced need for ECMO.63,64.
POSTOPERATIVE SEDATION AND ANALGESIA
HEMODYNAMIC SUPPORT IN THE NEWBORN
In the newborn, where the myocardium is relatively immature, the ability to increase stroke volume is small. In order to choose the right therapeutic option when dealing with low cardiac output in a newborn, it is important to know what effects vasodilators and inotropes have on blood circulation in this situation.
INOTROPES Dopamine
It stimulates both a and b receptors in a dose-dependent manner; at low doses (0.050.1 mg/kg per minute) it mainly affects receptors resulting in inotropic and chronotropic effects. At higher doses (0.21.0 mg/kg per minute) it is a potent vasoconstrictor, a stimulus that increases MAP and diastolic pressure.
VASOCONSTRICTORS
Experience with its use in children generally parallels that in the adult literature with an increase in cardiac index and MAP in a dose-dependent manner with doses from 2 to 7.5 mg/kg per minute.99101 Neonatal experience usually has been in the treatment of PPHN, often in combination with dopamine. In such cases, we would start an adrenaline infusion at 0.05 mg/kg per minute, increasing to 0.1 mg/kg per minute according to response, sometimes combined with vasodilator therapy.
VASODILATORS
There are several studies of the effective use of phosphodiesterase inhibitors in the treatment of low cardiac output after open heart surgery in infants.128134 The most commonly used drug in this class is milrinone in a dose of 0.251mg/kg per minute. The drug has a long half-life and its metabolism is prolonged in liver or kidney failure.135 136 A recent study of milrinone in premature infants showed no difference in superior vena cava (SVC) flow at a dose of 0.2mg/ kg per minute compared to placebo.137.
FLUID MANAGEMENT AND RENAL FUNCTION
A recent innovation in pharmacotherapy for the management of low cardiac output has been the introduction of phosphodiesterase inhibitors, which work by blocking the breakdown of cGMP. Management of acute renal failure consists of eliminating the underlying cause if possible, limiting fluids to urine output plus insensible losses, and treating hyperkalemia with dextrose infusions and potassium exchange resins.
TEMPERATURE REGULATION AND METABOLISM IN THE NEONATE
METABOLISM IN THE NEWBORN Glucose and calcium
Kinsella JP, Truog WE, Walsh WFet al.Randomized, multicenter trial of inhaled nitric oxide and high-frequency oscillatory ventilation in severe, persistent pulmonary hypertension of the newborn.J Pediatr. Steinhorn RH, Kinsella JP, Pierce C et al. Intravenous sildenafil in the treatment of neonates with persistent pulmonary hypertension. J Pediatr.
JOSEPH CHUKWU, WINIFRED A GORMAN, AND ELEANOR J MOLLOY
WATER DISTRIBUTION IN THE FETUS AND THE NEWBORN INFANT
FUNCTIONAL ADJUSTMENTS TO POSTNATAL LIFE
Sweating occurs only to a very limited extent in response to a thermal stimulus in the full-term infant, despite the fact that it does. The evaporation of water from the skin surface occurs continuously by diffusion.25,26 The amount of water lost is determined by the relative humidity of the infant's surrounding atmosphere, especially in premature infants with immature skin keratinization.
FLUID AND ELECTROLYTE MANAGEMENT
During the first 24 hours of life, urine output may be very low or even absent. Hypernatremia may occur, especially in the very low birth weight infant, and may have adverse effects.51.
PERIOPERATIVE MANAGEMENT
Symptoms are uncommon at serum calcium above 1.8 mmol/L and become common at serum calcium B1.5 mmol/L. Oral calcium supplements in the form of Calcium Sandoz provide 2.7 mmol (110 mg) of elemental calcium. 2.5 ml (50 mg) per kg per day may be given with food if the fed infant has asymptomatic hypocalcemia requiring treatment.
FLUID AND ELECTROLYTE BALANCE IN SEPTIC SHOCK
This should be addressed by correcting the underlying cause of acidosis and giving sodium bicarbonate. Thus, early attention should be given to initiating parenteral nutrition in infants for whom early feeding is not provided.
ACUTE RENAL FAILURE
Vanhaesebrouck S, Zonnenberg I, Vandervoort P et al. Conservative treatment for patent ductus arteriosus in premature infants. Stephens BE, Gargus RA, Walden RVet al. Fluid regimens in the first week of life may increase the risk of patent ductus arteriosus in extremely low birth weight infants.
AGOSTINO PIERRO AND SIMON EATON
HISTORICAL BACKGROUND
BODY COMPOSITION
This is only 2 days at 2425 gestational weeks, increases to 20 days at term as glycogen and fat stores increase (Fig. 13.1)6 and is over 50 days in the adult, hence the urgent need for adequate caloric intake in very low birth weight ( VLBW) and/or extremely low birth weight (ELBW) infants after birth.
ENERGY REQUIREMENTS OF THE NEONATE
From these studies, it is clear that the metabolic rate and hormonal response to surgery, stress and sepsis in infants may well be different from that of adults and therefore it is not possible to adjust nutritional recommendations for them. This may explain the lack of growth commonly observed in infants with critical illness or sepsis.
PARENTERAL NUTRITION Indications
Lacey JM, Crouch JB, Benfell Ket al. Effects of parenteral nutrition supplemented with glutamine in preterm infants. JPEN J Parenter Enteral Nutr. Becker RM, Wu GY, Galanko JA et al. Decreased serum amino acid concentrations in infants with necrotizing enterocolitis. J Pediatr.
SEAN J BARNETT AND FREDERICK C RYCKMAN
ARTERIAL CANNULATION
Umbilical artery catheters have a higher risk of thromboembolism, especially if placed in a low-lying position (L3L5).4 The infection rate is similar to that of central venous catheters.3 We tend to use these catheters within five days of placement. to help prevent these problems. Studies have also shown that there is no evidence that prophylactic antibiotics are helpful with these catheters.5.
UMBILICAL ARTERY CATHETERIZATION
The catheter is then moved to the desired position and secured with a suture through the cord material. The desired fluids and measuring devices are then attached to the catheter using a three-way mechanism or manifold.
ALTERNATIVE METHOD FOR CANNULATION
A pre-flushed catheter of 3.5 Fr (infants less than 2 kg) or 5 Fr (infants over 2 kg) is then introduced into the lumen with gentle traction on the umbilical stump.
RADIAL ARTERY CANNULATION
PEDAL ARTERIAL CANNULATION
AXILLARY AND FEMORAL ARTERIAL CANNULATION
Percutaneous access can be obtained via the axillary artery with the arm extended beyond horizontal and mid-course. Access to the femoral artery can be achieved under the inguinal ligament, also by percutaneous methods.
VENOUS CANNULATION
PICC lines can be inserted as a bridge to replace more permanent access during antibiotic treatment of the bacteremia. With careful guidelines for the placement and maintenance of these catheters, very low infection rates can be achieved.
PERIPHERALLY INSERTED CENTRAL CATHETER
Although many authors advocate antibiotic treatment to clear central line infection, removal of the foreign body (CVC) associated with the infection may be necessary in refractory cases. Insertion site infections can generally be treated with antibiotics alone and do not require catheter removal unless bacteremia is documented.
UMBILICAL VEIN CATHETER
Numerous other bacteria, including Gram-negative, anaerobic, and Candida species, can cause line infection, especially in the postsurgical newborn. Access can also be obtained in acute situations in the operating room of the newborn by a supraumbilical incision with gentle dissection and cannulation of the ductus venosus.
PERCUTANOUS CANNULATION
Catheters are gently advanced usually only 12 cm past the point of blood return (generally only about 5 cm in a full-term baby).
PERIPHERAL VEIN CUT-DOWN
The catheter is then advanced and the proximal suture is tied to secure the line and the vessel. The incision is then closed in the usual way and the line site is dressed as previously described.
INTRAOSSEOUS DEVICES
Wright IMR, Owers M, Wagner M, The umbilical arterial catheter: A formula for improved positioning in the very low birth weight infant. Crowley JJ, Pereira JK, Harris LS et al. Peripherally inserted central catheters: Experience in 523 children.Radiology1997;.
J KELLEHER AND IAN HW ROBINSON
CONVENTIONAL RADIOGRAPHY
Where repeated examination of the chest and mediastinum is expected, the use of thyroid shielding should be considered. Good X-ray technique is essential to produce high-quality X-ray images, thus avoiding unnecessary extra exposure and disturbance to babies due to repeated exposure.2 Sufficient numbers of well-trained and experienced X-ray technicians should be available to ensure that these high standards are maintained.
MOBILE EXAMINATIONS
High-frequency generators, added beam filtration, and digital image receptors contribute significantly to reducing radiation exposure to the infant.1 The beam should be collimated to cover only the appropriate area, and gonadal protection with lead shields should be used. The infant may be left comfortably in this position for some time to ensure that the gas clears the distal border of the blind rectal pouch (Fig. 15.4a,b).
FLUOROSCOPIC EXAMINATIONS
It is unacceptable to take the baby out of the incubator and hold it upside down by the legs during exposure. Besides the trauma to the baby, it is difficult to get a good true lateral view centered at the correct level.
ULTRASONOGRAPHY
When evaluating space-occupying lesions of the neonatal abdomen, ultrasound should be the first investigation. In neonatal jaundice, US plays a key role in defining bile duct anatomy.
NUCLEAR MEDICINE
COMPUTED TOMOGRAPHY
Regardless of the type of hypoxic injury, imaging manifestations are related to the gestational maturity of the infant. In the evaluation of mass lesions in the neck and mediastinum, it provides exquisite anatomical detail.
INTERVENTIONAL TECHNIQUES
