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Chapter 24.docx

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McGill University
NUR1 233
Sonia Elizabeth Semenic

Chapter 24 Physiological Adaptations of the NewbornPhysiological AdjustmentsRespiratory SystemWhen cutting umbilical cord most cirtical and immediate adjustment is establishment of respirationsVaginal birth some lung fluid is squeezed from trachea and lungsCesarean birth some lung fluid may be retained within alveoliWith first breath of air newborn begins a dynamic sequence of cardiopulmonary changesInitial breathing result of a reflex triggered by pressure changes cool air temp noise light etcChemoreceptors in aorta and carotid bodiesinitiate neurological reflexes when PO2 falls or PCO2 rises and pH fallsI minute of birth exaggerated respiratory reaction and the infant takes the first gasping breath and criesLater respirations establishedshallow and irregular3060 breathsminwith periods of periodic breathing that include pauses in respirations lasting less than 20sPeriodic breathing occur most often during active REM sleep cycle and decrease in frequency and duration with ageAnetic periods lasting 20s or longer indicatoin of a pathological process and should be carefully evaluatedSigns of respiratory distress o Nasal flaring intercostal or subcostal retractions grunting with respirations o Upper airway obstruction suprasternal or subclavicular retractions with stridor or gaspingo Seesaw or paradoxical respirations exaggerated rise in abdomen with respiration as chest falls instead of abdominal respirations o RR30 breathsmin or60 breathsmin with infant at rest o Can be negative influenced slowed depressed or absent by analgesics or anesthetics administered to mother during birth o Apneic episodes related to body temp hypothermia hypoglycemia and sepsis o Tachypnea related to inadequate clearnace of lung fluid or respiratory distress syndromeMaintaining adequate oxygen supply o First hour pulmonary lymphatics continue to remove large amounts of fluidAlso result of pressure gradient from aleoli to interstitial tissue to blood capillary o Rention of lung fluid may interefered with infants ability to maintain adequate oxygenation o Chest circumference 3033cm at birth o Ausculatation loud clear breath sounds and seem very near because there is less chest wall musculature o Ribs Ribs articulate with spine at a horizontal rather than downward sloperib cage cannot expand with inspiration as much as adultso Abdominal breathing normalchest and abdomen rise simultaneously with inspiration but because of large size of abdomen chest movement is not as visible o Surfactant absent or decreased could cause increase pressure exhaust preterm or sick term infantsCardiovascular SystemReduced pulmonary vascular resistance to pulmonary blood flow from the pulmonary arteriesPulmoary artery pressure drops and pressure in RA declinesIncreased pressure in LAcauses functional closure of the foramen ovale o When baby cries may temporarily reverse flow through foramen ovale and lead to mild cyanosisPO2 in utero 27mmHgPO2 at birth 50mmHgductus arteriosus constricts in respose to increased oxygenationhormone prostaglandin levels also have role in closing ductus arteriosusClamping of cord umbilical arteries and umbilical vein and ductus venosus close and are converted to ligamentsHypogastric arteries occulude and become ligamentsHeart rate and sounds o At birth 120140 bpmvariations at sleeping and waking o Range 8090 bpm when sleeping170180 bpm when crying o Consistently high or consistently low at rest should be reevaluated within an hour tho Apical impulse 4 ICS left of midclavicular line Precordial activity PMI visible and palpable because of thin chest wall
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