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- Anatomy and Physiology in Neonates and Children
- Anatomy and Physiology in Neonates and Children
- Pediatric Airway Pathology
This article is only available in the PDF format. Download the PDF to view the article, as well as its associated figures and tables. The second in a series of four volumes dealing with the question of growth and development concerns itself with the anatomy and physiology of the whole body.
Oxford University Press makes no representation, express or implied, that the drug dosages in this book are correct. Readers must therefore always check the product information and clinical procedures with the most up to date published product information and data sheets provided by the manufacturers and the most recent codes of conduct and safety regulations. The authors and the publishers do not accept responsibility or legal liability for any errors in the text or for the misuse or misapplication of material in this work.
Liver function is initially immature with decreased function of hepatic enzymes. Barbiturates and opioids for example have a longer duration of action due to the slower metabolism. Hypoglycaemia is common in the stressed neonate and glucose levels should be monitored regularly.
Glycogen stores are located in the liver and myocardium. Neurological damage may result from hypoglycaemia. Hyperglycaemia is usually iatrogenic. Use this time to develop rapport and trust with the child and parent. Address the child first and then include the parents in discussion. Address the queries and fears of the child as well as those of the parent. Explain the planned approach to induction so both parent and child know what to expect.
It is important to take a medical and anaesthetic history. Conduct a physical examination as appropriate concentrating on the airway and cardio-respiratory systems. Children must be weighed.
All drug doses relate to body weight. Investigations may occasionally be necessary: o Haemoglobin — large expected blood loss, premature infants, systemic disease, congenital heart disease o Electrolytes — renal or metabolic disease, intravenous fluids, dehydration o CXR — active respiratory disease, scoliosis, congenital heart disease Discuss post-operative pain management. If suppository medications are to be used, consent should be obtained from the parent and the child if they are able to understand.
You are not currently logged in. Anatomy Anatomy for anaesthetists. Beta-blockers Inhalational agents Local anaesthetics Opioids Pharmacology. Articles Literature Review. Respiratory articles. Pathophysiology Pathophysiology: Articles. Potential therapies: Articles Potential therapies: Literature.
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Neurosciences - Articles. Metabolic - articles and literature. Gastro - articles and literature. Cardiac articles and literature. FRCA exam courses. Macfarlane mater. Paediatric patients vary considerably and include the following groups: Neonates — a baby within 44 weeks of age from the date of conception Infants — a child of up to 12 months of age Child — 1 to 12 years Adolescent — 13 to 16 years The differences between paediatric and adult anaesthetic practice are reduced as the patients become older.
The important anatomical and physiological differences will be considered below followed by a discussion of how these will affect anaesthetic practice. The tongue is relatively large. The larynx is high and anterior, at the level of C3 - C4. The epiglottis is long, stiff and U-shaped. It flops posteriorly. The head needs to be in a neutral position. Neonates preferentially breathe through their nose. Their narrow nasal passages are easily blocked by secretions and may be damaged by a nasogastric tube or a nasally placed endotracheal tube.
The airway is narrowest at the level of the cricoid cartilage. Here, pseudo-stratified, ciliated epithelium is loosely bound to the underlying areolar tissue. Trauma to the airway easily results in oedema. It is suggested that a leak be present around the endotracheal tube to prevent trauma resulting in subglottic oedema and subsequent post-extubation stridor. The trachea is cm long and funnel shaped. An endotracheal tube must be inserted to the correct length to sit at least 1cm above the carina and be taped securely so as to prevent tube dislodgement with head movement or an endobronchial intubation.
The neonate and infant have limited respiratory reserve. Ventilation is primarily diaphragmatic. Bulky abdominal organs or a stomach filled with gases from poor bag mask ventilation can impinge on the contents of the chest and splint the diaphragm.
The chest wall is significantly more compliant than that of an adult. Subsequently, the functional residual capacity FRC is relatively low. FRC decreases with apnoea and anaesthesia causing lung collapse. Minute ventilation is rate dependant as there is little means to increase tidal volume. The closing volume is larger than the FRC until years of age. This causes an increased tendency for airway closure at end expiration. CPAP during spontaneous ventilation improves oxygenation and decreases the work of breathing.
Muscles of ventilation are easily subject to fatigue due to low percentage of Type I muscle fibres in the diaphragm. This number increases to the adult level over the first year of life. The alveoli are thick walled at birth. The alveoli clusters develop over the first 8 years of life. Apnoeas are common post operatively in premature infants.
Apnoeas are significant if they last longer than 15 seconds and are associated with desaturation or bradycardia. This limits the size of the stroke volume. Cardiac output is therefore rate dependent. The infant behaves as with a fixed cardiac output state. Vagal parasympathetic tone is the most dominant, which makes neonates and infants more prone to bradycardias. Bradycardia is associated with reduced cardiac output.
Bradycardia associated with hypoxia should be treated with oxygen and ventilation initially. External cardiac compression will be required in the neonate with a heart rate of 60 beats per minute or less, or if the rate is beats per minute with adequate ventilation.
Sinus arrhythmia is common in children and all other irregular rhythms are abnormal. Closure of the foramen ovale is pressure dependent and closes in the first day of life but it may reopen within the next 5 years. However, with alterations in pressure and in response to hypoxia and acidosis, reversion to the transitional circulation may occur in the first few weeks after birth.
Tubular function is immature until 8months, so infants are unable to excrete a large sodium load. Dehydration is poorly tolerated. Premature infants have increased insensible losses as that have a large surface area large surface area relative to weight. HbF combines more readily with oxygen but is then released less readily as there is less 2,3-DPG. HbF is protective against red cell sickling. Vitamin K is given at birth to prevent haemorrhagic disease of the newborn. They have poorly developed shivering, sweating and vasoconstriction mechanisms.
Brown fat located in small amounts around the scapulae, the mediastinum, the kidneys and adrenal glands metabolism is required for non-shivering thermogenesis. More oxygen is required for the metabolism of these brown fat stores.
Heat lost during anaesthesia is mostly via radiation but may also be lost by conduction, convection and evaporation. Low body temperature causes respiratory depression, acidosis, decreased cardiac output, increases the duration of action of drugs, decreases platelet function and increases the risk of infection. Narcotics depress the ventilation response to a rise in PaC0 2. The blood brain barrier is poorly formed.
Drugs such as barbiturates, opioids, antibiotics and bilirubin cross the blood brain barrier easily causing a prolonged and variable duration of action. The cerebral vessels in the preterm infant are thin walled, fragile. They are prone to intraventricular haemorrhages. The risk is increased with hypoxia, hypercarbia, hypernatraemia, low haematocrit, awake airway manipulations, rapid bicarbonate administration and fluctuations in blood pressure and cerebral blood flow.
Cerebral autoregulation is present and functional from birth. Children up to 4 years of age are upset by the separation from their parents and the unfamiliar people and surroundings. It is difficult to rationalise with a child of this age. The behaviour of this group is more unpredictable. School age children are more upset by the surgical procedure, its mutilating effects and the possibility of pain. Adolescents fear narcosis and pain, the loss of control and the possibility of not being able to cope with the illness.
This is worsened by long periods of hospitalisation.
Anatomy and Physiology in Neonates and Children
General and central nervous system anatomy and physiology in children is different to that of adults and this is relevant to traumatic brain injury TBI and spinal cord injury. The controversies and uncertainties in adult neurotrauma are magnified by these differences, the lack of normative data for children, the scarcity of pediatric studies, and inappropriate generalization from adult studies. Cerebral metabolism develops rapidly in the early years, driven by cortical development, synaptogenesis, and rapid myelination, followed by equally dramatic changes in baseline and stimulated cerebral blood flow. Therefore, adult values for cerebral hemodynamics do not apply to children, and children cannot be easily approached as a homogenous group, especially given the marked changes between birth and age 8. Their cranial and spinal anatomy undergoes many changes, from the presence and disappearance of the fontanels, the presence and closure of cranial sutures, the thickness and pliability of the cranium, anatomy of the vertebra, and the maturity of the cervical ligaments and muscles. Moreover, their systemic anatomy changes over time. The head is relatively large in young children, the airway is easily compromised, the chest is poorly protected, the abdominal organs are large.
Basics pp Cite as. Pediatric anesthesia involves patients ranging from preterm infants to teenagers, and these groups require different anesthetic equipment and techniques. Successful and safe anesthetic management in pediatric patients depends on an appreciation and clear understanding of the physiological, anatomic, pharmacological and psychological differences among the pediatric age groups and between pediatric and adult patients. Changes in the airways, cardiovascular system, renal function, central and autonomic nervous system, gastrointestinal system and thermoregulation that take place during development make anesthetic management different and extremely challenging. Pediatric anesthesia management requires an understanding and knowledge of the differences and characteristics unique to the child and infant.
Oxford University Press makes no representation, express or implied, that the drug dosages in this book are correct. Readers must therefore always check the product information and clinical procedures with the most up to date published product information and data sheets provided by the manufacturers and the most recent codes of conduct and safety regulations. The authors and the publishers do not accept responsibility or legal liability for any errors in the text or for the misuse or misapplication of material in this work. Except where otherwise stated, drug dosages and recommendations are for the non-pregnant adult who is not breastfeeding. Anaesthesia for children is tempered by changes that occur during both growth and development.
Janet MacGregor is Senior Lecturer in Nursing Science and Paediatrics at. Christchurch College, Canterbury. Introduction to the Anatomy and Physiology.
Anatomy and Physiology in Neonates and Children
The infant and child differ structurally from the adult in a number of ways which are critical to the design for protection against impact forces and for adequate occupant restraint systems. The purpose of this paper is to bring together a profile of the anatomy, anthropometry, growth and development of the infant and child. Age differences related to the proper design of child restraint systems are emphasized. Problems discussed include child--adult structural differences, center of gravity of the body, the head mass in relation to the neck and general body proportions, positions of key organs, and biomechanical properties of tissues. Infants and children are not miniature adults.
NCBI Bookshelf. The pediatric population often responds to drugs and other therapeutics differently than adults do. Generally, the guidelines that practitioners use when they prescribe drugs have not been based on biologic or pharmacologic principles when they extrapolate the drug doses used for adults to infants and children. Not only have the guidelines tended to be simplistic in that they assume a linear relationship between children and adults, but they have also not made allowances for the complex changes in growth and development that take place during childhood. A number of quantitative and qualitative differences in the anatomy and physiology of the infant and developing child can affect the absorption, distribution, metabolism, and excretion of various drugs and other xenobiotic compounds.
Pediatric Airway Pathology
Summary: Mader's Understanding Human Anatomy and Physiology continues to be the perfect text for a one-semester course, because it was designed for this audience from the very first edition. The text is celebrating its tenth anniversary with a complete facelift, which I believe makes the content even more approachable, user friendly and exciting. Each chapter now begins with an infographic that details fascinating facts about the chapter's subject. Solutions to the problems are developed using the language C and the author's signature five-step problem solving process. What does she do? More very low-level yet high-interest stories! These stories, selected from mainstream news sources, are humorous, poignant, astounding -- and all true!
Edited by Jonathan G Hardman, Philip M Hopkins, and Michel M.R.F Struys
As the lungs expand and contract, oxygen rich air is inhaled and carbon dioxide is removed. Breathing begins at the mouth and nose where air is inhaled. The air travels to the back of the throat, into the trachea and then divides into the passages known as the bronchial tubes. The bronchial tubes continue to divide as the go deeper into the lungs and the air is carried to the alveoli. Oxygen passes through the walls of the alveoli and into the blood vessels that surround these tiny sacs.
Congenital or acquired disorders of the pediatric airway can affect the upper, lower, or entire airway. There are fundamental differences between the anatomy and physiology of the neonate, pediatric, and adult airways. Infants are not merely small adults in this respect and size, surface area, proportion, resistance, and compliance vary greatly between the age groups.