Newborn Care: Oxygen therapy

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Newborn Care was written for healthcare workers providing special care for newborn infants in level 2 hospitals. It covers: resuscitation at birth, assessing infant size and gestational age, routine care and feeding of both normal and high-risk infants, the prevention, diagnosis and management of hypothermia, hypoglycaemia, jaundice, respiratory distress, infection, trauma, bleeding and congenital abnormalities, communication with parents

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Newborn Care: Oxygen therapy

  1. 1. 11 Oxygen therapy animals. Oxygen is essential for many living Objectives organisms. 11-2 Why does the body need oxygen? When you have completed this unit you will be able to: Energy for all the vital functions of the body is obtained by either aerobic or anaerobic • Explain why the body needs oxygen. metabolism: • List the indications for oxygen therapy. • Describe the dangers of oxygen 1. Aerobic metabolism releases energy from carbohydrates, proteins and fats by the administration. process of oxygenation. Aerobic metabolism • Understand the methods used to give is used by most cells, as it produces large oxygen safely. amounts of energy for prolonged periods of • List what equipment is needed to time, but requires the presence of oxygen. administer oxygen. 2. Anaerobic metabolism, in contrast, does • Understand the advantages of not need oxygen but is far less efficient as it produces small amounts of energy and continuous positive airways pressure. only functions for short periods of time. Therefore the body needs oxygen to produce the large amount of energy required for mostOXYGEN THERAPY body functions such as moving, breathing, eating and digestion. In the body, oxygen is carried by haemoglobin11-1 What is oxygen? in red blood cells from the lungs to all theOxygen is one of the many gases that make other organs. When loaded with oxygen theup the earth’s atmosphere. It is produced by haemoglobin and red blood cells are red ingreen plants (photosynthesis) and used by all colour and as a result the infant appears pink.
  2. 2. 206 NEWBORN CAREHowever, if the red blood cells carry too little with the percentage of oxygen saturation inoxygen they become blue in colour and the the blood.infant appears cyanosed. 11-6 How much oxygen is present in room Oxygen is needed by the body to release large air? amounts of energy stored in carbohydrates, The atmosphere of earth consists of a mixture proteins and fats of many gases such as nitrogen, oxygen and carbon dioxide. Oxygen forms 21% of the gas in the atmosphere. Therefore the fraction of11-3 What is cyanosis? oxygen in room air is 0.21. This is true, both at sea level and at high altitudes, and is adequateThis is the blue colour of the body due to too to meet the needs of aerobic metabolism inlittle oxygen. The cyanosed infant may have adults and newborn infants.central cyanosis, when the tongue is blue, orperipheral cyanosis, when the hands and feet NOTE The atmosphere exerts a pressure asare blue. demonstrated by the collapse of a soap bubble. The total pressure in the atmosphere is approximately 100 kPa (760 mm Hg) at sea level;11-4 What is hypoxia? 21% of this total pressure is produced by oxygen.Hypoxia is the lack of enough oxygen in the Therefore, the partial pressure of oxygen in thetissues. It causes cyanosis. Hypoxaemia is too atmosphere is 21% of 100 kPa (760 mm Hg), which is 21 kPa (160 mm Hg).little oxygen in the blood. Hypoxaemia resultsin hypoxia. The FiO2 (fraction of inspired oxygen) of room air is 0.21MEASURING THE AMOUNTOF OXYGEN 11-7 How do you determine the amount of oxygen in the blood?11-5 How is the amount of oxygen in the 1. This can be roughly assessed clinicallyatmosphere measured? as the infant appears peripherally and centrally cyanosed if there is not enoughThe amount of oxygen in the atmosphere is oxygen in the red cells. This clinicaldetermined by measuring its concentration or method is often inaccurate and should,partial pressure: whenever possible, be confirmed by1. The concentration of oxygen is given as measuring either the saturation of oxygen a percentage (e.g. 40%) or as a fraction or the partial pressure in arterial blood. (e.g. 0.40). 2. At the bedside the saturation of oxygen2. The partial pressure of oxygen is measured in arterial blood can be measured with in kilopascals (kPa) or millimetres of a pulse oximeter (a saturation monitor), mercury (mm Hg). which simply clips onto the infant’s handThe concentration of oxygen in room air is or foot and measures the oxygen saturationusually called the fraction of inspired oxygen, through the skin. A pulse oximeter can beand abbreviated to FiO2. For example, the FiO2 used to accurately screen for hypoxaemia.is 0.40 if the percentage oxygen is 40%. It is 3. In a laboratory the partial pressure ofpreferable to speak about the fraction rather oxygen can be measured accurately in athan the percentage of oxygen in inspired air sample of arterial blood using a machine(breathed in air) as the latter is often confused called a blood gas analyser, which measures the pH and concentration
  3. 3. OXYGEN THERAPY 207 of oxygen and carbon dioxide. The haemoglobin in arterial blood is fully loaded partial pressure of oxygen in venous or with oxygen. The degree of saturation of capillary blood is usually not used as it arterial blood with oxygen is referred to as the does not reflect accurately the amount of SaO2. Therefore, at a FiO2 of 0.21 the SaO2 in a oxygen reaching the tissues. Taking an newborn infant is normally 86–92%. arterial blood sample if often painful and distressing to the infant. The normal SaO2 (saturation of oxygen in arterial NOTE A pulse oximeter determines the saturation blood) is 86–92% of oxygen in the arterial blood entering the capillaries by assessing the colour of the red cells. The red cell colour is determined through the NOTE The SaO2 is determined by the PaO2 and the skin and does not require a sample of blood. A haemoglobin’s ability to take up oxygen. The SaO2 sample of capillary blood can be used to measure increases in a linear manner as the PaO2 rises until the partial pressure provided that the puncture the SaO2 reaches 92%. Thereafter there is a poor site (e.g. heel) is warmed and the blood allowed correlation between the two measurements. This to run without squeezing. The result is very explains why a SaO2 above 92% is potentially similar to arterial blood provided the sample is dangerous as the PaO2 may be very high. While collected correctly. the normal range of SaO2 is slightly higher in term than preterm infants, for practical reasons a common normal range of 86–92% is used. The11-8 How much oxygen is needed by the normal range of SaO2 in older children and adultsnormal infant? is above 95% (as they have adult haemoglobin).Healthy, normal infants (and adults) need 21%oxygen in the air they breathe (i.e. a FiO2 of0.21). THE ADVANTAGES AND DISADVANTAGES OF11-9 What is the normal partial pressure ofoxygen in arterial blood? EXTRA OXYGENNormally a FiO2 of 0.21 in the inspired air(i.e. room air) produces a partial pressure 11-11 When does an infant need extraof oxygen in the arterial blood of 8–10 kPa oxygen?(60–75 mm Hg). The partial pressure of If the PaO2 in both term and preterm infantsoxygen in arterial blood is referred to as the falls below 8 kPa and the SaO2 falls below 86%.PaO2. Therefore a PaO2 of 8–10 kPa is normal At these levels (hypoxaemia) the red cells willand adequate to fully load the haemoglobin not be adequately loaded with oxygen. Thein the circulating red blood cells with oxygen. infant may now appear cyanosed and the cellsIn South Africa kPa is the unit usually used to of the body will not receive enough oxygen forexpress partial pressure. aerobic metabolism (hypoxia). Therefore, extra oxygen is needed in the inspired air (i.e. a FiO2 The normal PaO2 (partial pressure of oxygen in of more than 0.21) if: arterial blood) is 8–10 kPa 1. The infant has central cyanosis (a blue tongue). 2. The PaO2 drops below 8 kPa.11-10 What is the normal saturation of 3. The SaO2 falls below 86%.oxygen in arterial blood?The normal saturation of oxygen in arterial 11-12 Is too little oxygen dangerous?blood is 86–92% in newborn infants breathing Yes. If the cells of the body do not receiveroom air. At this oxygen saturation the enough oxygen they can be damaged or die.
  4. 4. 208 NEWBORN CAREWithout adequate oxygen, cells are forced to recurrent apnoea but no respiratorychange from aerobic to anaerobic metabolism. distress usually do not need oxygen.This markedly reduces the amount of energy 5. Small, preterm infants with a normal PaO2the cells can produce. Toxic substances, such and SaO2.as lactic acid, are also produced as a by- A normal SaO2 indicates that extra oxygen isproduct of anaerobic metabolism. This causes not needed.a metabolic acidosis. The cells of many organs,but particularly the brain, are affected by thesemetabolic changes. Only give extra oxygen when there is a good clinical indication Too little oxygen in the blood can cause brain damage 11-15 When indicated, how much oxygen should you give?11-13 Which infants are usually given extra The FiO2 should be increased until:oxygen? 1. Central cyanosis is corrected (the tongueInfants with respiratory distress due to clinical is pink).conditions such as hyaline membrane disease, 2. The PaO2 is 8–10 kPa or SaO2 is 86–92%.pneumonia and meconium aspiration. Extra The required FiO2 to keep different infantsoxygen may also be needed by some infants pink may vary from 0.22 to 1 (i.e. 21 to 100%).who require resuscitation at birth. For example, an infant with severe lungA pulse oximeter is very helpful when deciding disease may need a FiO2 of 0.9 while anotherwhether an infant needs extra oxygen. with mild lung disease may need only 0.25 to achieve a normal PaO2 and SaO2. A pulse oximeter is very helpful in deciding 11-16 Can you give an infant too much whether extra oxygen is needed oxygen? Yes. If the FiO2 is increased too much, the11-14 Which infants do not need extra PaO2 and SaO2 will rise above the normaloxygen? range. If the PaO2 is above 10 kPa or SaO2 above 92%, the excessive amount of oxygen in1. Infants with normal Apgar scores at birth. the blood may damage the infant. Do not give oxygen to infants who do not need resuscitation. If a particular infant needs an FiO2 of 0.35 to2. Many infants with low Apgar scores can be give a normal PaO2 and SaO2, increasing the successfully resuscitated with room air. Not FiO2 to 0.50 will be of no additional help to all infants needing resuscitation require the infant and may be dangerous. Therefore, extra oxygen. do not give oxygen unless it is needed. Also3. Some infants with peripheral but not central do not give more oxygen than is required. In cyanosis. If there is peripheral cyanosis only, an emergency, oxygen should be given for as the cause is usually cold hands and feet with short a time as possible. Giving oxygen can be poor perfusion, rather than hypoxia. dangerous when it is not required.4. Many infants with recurrent apnoea. If NOTE A SaO2 above 96% is safe if the infant is in oxygen is given during resuscitation, it room air and not receiving oxygen. They will should be stopped once spontaneous always have a normal PaO2. respiration has started. Infants with
  5. 5. OXYGEN THERAPY 209 of retinopathy recover and vision is not Too much oxygen is dangerous as it may damage affected. However, severe retinopathy with the infant a lot of fibrosis causes a condition known as retrolental fibroplasia which can permanently impair vision and even result in blindness.11-17 When is the concentration ofinspired oxygen too high? The lower the gestational age the greater is the risk of retinopathy of prematurity. TheAny FiO2 that increases the PaO2 or SaO2 above risk of retinopathy is greatest in infants underthe normal range is too high. It is impossible 32 weeks gestation. At term the risk of oxygento tell by clinical examination alone that the toxicity to the retina is much less. RetinopathyFiO2 is too high. The risk of oxygen damage is is diagnosed by examining the eye with andetermined by the PaO2 or SaO2 and not by the ophthalmoscope.FiO2. A high FiO2 is not dangerous if the PaO2or SaO2 are normal (e.g. with severe respiratorydistress). A high FiO2 is most dangerous if there 11-20 How can you prevent retinopathy ofare no lung or heart problems, e.g. oxygen given prematurity?to healthy preterm infants during transport. Most cases of retinopathy can be prevented by adjusting the FiO2 so that the PaO2 and11-18 What are the dangers of too much SaO2 are within the normal range. If theseoxygen in the blood? investigations are not available, give just enough oxygen to correct central cyanosis,1. If the PaO2 is too high, the retina of the i.e. just enough to keep the tongue pink. infant’s eyes can be damaged causing retinopathy of prematurity. However, if NOTE Unfortunately the cause of retinopathy is a very high FiO2 is needed to maintain a not fully understood and some very immature normal PaO2 and SaO2, the retina is not infants may still get eye damage despite careful likely to be damaged. Therefore, it is the oxygen control. Infants of less than 32 weeks gestation should be screened for retinopathy at 6 raised PaO2 and not the increased FiO2 that weeks by direct fundoscopy. causes retinopathy. The longer the period during which the PaO2 is too high, the greater is the risk of retinopathy.2. A high FiO2 for a long time, especially if ADMINISTERING OXYGEN the infant is intubated and on a ventilator, SAFELY may damage the alveoli and small bronchi of the lung resulting in chronic lung disease (bronchopulmonary dysplasia). 11-21 What is a safe concentration of inspired oxygen? A high PaO2 in a preterm infant may cause No FiO2 above 0.21 can be regarded as safe retinopathy of prematurity unless the PaO2 or SaO2 are measured and found to be in the normal range. Even a slightly raised FiO2 in an infant with normal11-19 What is retinopathy of prematurity? lungs will give a high PaO2 and SaO2. An increased FiO2 is most dangerous in aThe immature blood vessels in the retina of preterm infant with recurrent apnoea but nopreterm infants constrict (go into spasm) when respiratory distress, as the PaO2 can becomeexposed to a high PaO2. This causes retinal very high while they are breathing well.ischaemia and haemorrhage with healing byfibrosis. This important eye problem is calledretinopathy of prematurity. Mild degrees
  6. 6. 210 NEWBORN CARE11-22 How can you safely administer the 2. Oxygen is can be given into a perspexcorrect amount of oxygen? head box if facilities are not available to use nasal cannulas. This is a simple andAs there are dangers in giving too much or too cheap method but is not as effective as nasallittle oxygen, the following principles must be cannulas and uses a lot of oxygen. However,followed to ensure that oxygen administration an FiO2 of well above 0.4 can be provided.is safe: It is a useful method if medical air or a1. It is very unusual for an infant to need a blender is not available. With an oxygen FiO2 of 1.0 (100% oxygen). At all times the monitor the FiO2 can be measured. A warm FiO2 must be matched to the infant’s needs. humidifier is not needed and there is no risk2. The FiO2 must be adjusted to give a PaO2 of of nasal obstruction or gastric distension. 8–10 kPa or a SaO2 of 86–92%. 3. Oxygen can be given via nasal prongs3. If monitoring and laboratory facilities are when continuous positive airways pressure not available, give just enough oxygen is needed. This is particularly effective in to correct central cyanosis. This clinical infants with respiratory distress. However, assessment is not accurate, however, so it medical air, a blender and warmed is best to determine the PaO2 or SaO2 if at humidifier are required. It is also important all possible. to have adequate, experienced nursing.4. The easiest method of monitoring oxygen 4. An endotracheal tube is used for most therapy is with a pulse oximeter to measure infants receiving oxygen via a ventilator. the SaO2 repeatedly or continuously. If The oxygen must be warmed, humidified continuous monitoring is not available, and blended with medical air. the SaO2 must be measured, at least every 5. A bag and mask are often used during 6 hours. As the infant’s clinical condition resuscitation. Some infants need oxygen improves or deteriorates, the required FiO2 during resuscitation. may need to be changed. There are advantages and disadvantages to5. Never give oxygen therapy unless it is each method of administering oxygen. indicated. Stop the oxygen therapy as soon as it is no longer needed. Nasal prongs are the best method of giving Monitoring the percentage oxygen saturation oxygen to newborn infants with a pulse oximeter is very important 11-24 What methods should not be used to administer oxygen?11-23 What methods can you use toadminister oxygen? 1. Oxygen should not be given directly into a closed incubator as this method is1. Oxygen can be given by short nasal wasteful, high concentrations of oxygen cannulas. The cannulas are about 1 cm cannot be reached and the concentration long and lie just inside the nostrils. This of oxygen drops every time an incubator is a simple and effective way of providing port is opened. extra oxygen. It is useful but not essential 2. Long nasal catheters are rarely used as they to use an air/oxygen blender. Warmed are often blocked with secretions. humidification and routine suctioning of 3. Giving 100% oxygen via a cardboard cup the nose are not needed. Low flow rates or face mask is extremely dangerous as it of 0.5 to 1 litres per minute are needed so is almost impossible to control the FiO2 little oxygen, a scarce resource, is used. accurately. This method should be used as However, with pure oxygen an FiO2 of only the last resort only. 0.4 can be reached.
  7. 7. OXYGEN THERAPY 2114. Gastric oxygen via a nasogastric tube is A blender or venturi should be used to control the valueless and dangerous. concentration of oxygen given11-25 Should you always humidify oxygen NOTE A venturi is a simple apparatus that uses aand medical air? jet of oxygen to suck in a fixed amount of roomOxygen or medical air direct from a cylinder or air. The resultant mixture of gases gives a knownwall piping is very dry and cold. It irritates the percentage of oxygen.airways and can drop the infant’s temperature,especially at high flow rates. Therefore, oxygen 11-27 What flow rate of oxygen is best?and medical air should be bubbled through 1. When oxygen is given via nasal cannulaswater at room temperature (a ‘bubbler’) if the flow rate should be set at 0.5 to 1 litrepossible when giving cannula or head box per minute. Do not use higher flow rates asoxygen. this only dries out the nose.Oxygen and medical air should always be 2. When oxygen is given into a headbox,humidified and warmed if it is being given either directly or via a blender or venturi,at high flow rates via nasal prongs or an the flow should be at least 5 litres perendotracheal tube. Warmed humidification minute to prevent carbon dioxideis not necessary if oxygen and medical air is accumulation. It is also very difficult togiven into a head box or by nasal cannulas accurately control the FiO2 by alteringas a low flow is inspired through the nasal the flow rate when low rates are used.passages, where it can be warmed and Alternately a high flow rate, such ashumidified. Dangers of humidifiers include 10 litres, wastes oxygen and cools theoverheating, drowning and infection. infant. With few exceptions, a flow rate of 5 litres per minute is best. NOTE Warmed humidification is needed at high flow rates (more than 2 litres per minute) which dry out the nasal mucus and mucous membranes. 11-28 Should the oxygen concentration in While warmed humidification is not needed at a head box be monitored? low flow rates (less than 2 litres per minute). Yes. The concentration of inspired oxygen should, whenever possible, be measured11-26 How should you control the with an oxygen monitor. This is the mostconcentration of oxygen given? accurate way of knowing what concentrationThe best way to control the FiO2 is with an of oxygen the infant is breathing from a headair-oxygen blender. A blender accurately box. If an oxygen monitor is not available, themixes pure oxygen with medical air to give the concentration of oxygen set on the air-oxygenrequired FiO2. A supply of both oxygen and blender or venturi is a good guide providedmedical air is needed for a blender. that the flow rate is 5 litres per minute or more.If a supply of medical air or a blender is notavailable, a venturi can be used with a head 11-29 How long should an infant receivebox. Some venturis mix pure oxygen with oxygen?room air to give any required FiO2 while others Only as long as it is required to prevent centralonly give a fixed FiO2 (e.g. 40%). The flow rate cyanosis and maintain a normal PaO2 andmust not be used to control the concentration SaO2. Tachypnoea alone is not an indicationof oxygen given as it is far too inaccurate. for supplementary oxygen. Whenever possibleWithout medical air and a blender the FiO2 the FiO2 should be reduced. Stop as soon ascannot be controlled if nasal cannulas, nasal possible. The time that oxygen is requiredprongs or an endotracheal tube is used. varies widely from one infant to another.
  8. 8. 212 NEWBORN CARE11-30 Are fluctuations in the oxygen 11-33 Is it safe to use an oxygenconcentration important? concentrator?Yes. Even small fluctuations in the FiO2 may In areas where piped or bottled (cylinder)cause a change in the PaO2 and SaO2. With oxygen is not available, an oxygen concentratorthe correct equipment a stable FiO2 can be can be used to concentrate oxygen from roommaintained. air. Modern concentrators are very efficient and can supply high concentrations of oxygen.11-31 How rapidly should you reduce theoxygen concentration? 11-34 What equipment do you need to give oxygen safely?The FiO2 must never be reduced suddenly in asingle big step. Instead it should be reduced in If oxygen is given without CPAP or ventilation:small steps at a time (e.g. an FiO2 decrease of 1. A source of pure (100%) oxygen. Either0.05 every 15 minutes). A sudden, large drop piped or cylinder oxygen is usually usedin FiO2 may cause severe hypoxia and collapse. in hospitals. The cylinder must have aNever stop the oxygen, even for a short time reducing valve and a gauge that measures(e.g. to take a blood sample), in an infant who the amount of gas present.still needs oxygen. A pulse oximeter is very 2. A source of medical air if possible. Eitherhelpful when the FiO2 is being reduced. piped or from a cylinder. NOTE Flip-flop is the name given to the clinical 3. Plastic tubing situation where a sudden, large drop in the 4. An oxygen flow meter FiO2 causes a dangerous drop in the PaO2 with 5. An oxygen-air blender if possible collapse and sometimes death. Increasing the 6. A venturi for head box oxygen if medical FiO2 back to the original level fails to correct the cyanosis. This is because of the development of air or a blender is not available pulmonary hypertension with a right to left shunt 7. A ‘bubbler’ to humidify the oxygen in response to the low PaO2. 8. Nasal cannulas or a perspex head box 9. An oxygen monitor if possible when head box oxygen is used. Never remove an oxygen-dependent infant from 10. A pulse oximeter (saturation monitor) if oxygen, even for a short period of time possible 11. A blood gas analyser in level 2 or 3 hospitals11-32 What oxygen sources can be used?1. Piped oxygen and medical air is the best source and should be available in all new- PROVIDING CONTINUOUS born intensive care and special care units. POSITIVE AIRWAYS2. Gas cylinders should be available in primary care units. A small oxygen cylinder can be PRESSURE (CPAP) used in emergencies in home deliveries.3. An oxygen concentrator. 11-35 What is continuous positive airwaysSome source of oxygen should be available pressure?for emergencies in all deliveries and in allnurseries. Continuous positive airways pressure (CPAP) is a method of providing respiratory support by allowing the infant to breathe out against pressure. The wider clinical use of CPAP has made a major difference to the management of infants with respiratory distress, especially
  9. 9. OXYGEN THERAPY 213those with hyaline membrane disease. Usually 11-39 When should CPAP be started inoxygen is given with CPAP but sometimes infants with respiratory distress?CPAP is used with room air only (e.g. in CPAP is indicated in most infants needinginfants with apnoea). extra oxygen, especially preterm infants with hyaline membrane disease. It is better to11-36 How does CPAP work to improve start CPAP early to prevent deterioration inrespiratory function? their respiratory distress than wait until theyNormally the alveoli of the lungs remain open need high percentages of oxygen. The earlyand do not collapse with expiration. However, use of CPAP prevents many infants needingin some respiratory complications in newborn mechanical ventilation.infants the alveoli tend to collapse and theseinfants are not strong enough to expand them The early use of CPAP often prevents the need foragain during every inspiration. As a result mechanical ventilationthe infant is not able to breathe normally andbecomes cyanosed (hypoxic) and may die.CPAP prevents alveoli collapse and also helps 11-40 How is CPAP given?to stimulate breathing, especially in infantswith apnoea. CPAP is usually given via nasal prongs with a special CPAP apparatus. This is a machineCPAP is not a form of mechanical ventilation. which is designed to control and deliverTherefore the infant must be able to breathe CPAP. It includes a blender, flow meter, warmspontaneously while receiving CPAP. humidifier and pressure gauge. The device is linked by tubes (pipes) to a nose piece which CPAP helps to keep the alveoli expanded has nasal prongs that are placed into the infant’s nostrils. There are 3 sizes of nasal prongs so that the nose piece can fit all newborn infants.11-37 Which infants benefit from CPAP? A Flow Driver is a commercial device to deliver CPAP. CPAP can also be given with a ventilatorInfants who suffer from mild or moderate: set on CPAP mode. Do not try to give CPAP1. Hyaline membrane disease with nasal cannulas as this is very unreliable2. Wet lung syndrome and ineffective.3. Meconium aspiration CPAP must be given in a newborn nursery4. Recurrent apnoea of prematurity (usually in a level 2 hospital) where the correct equipment is available and the staff have been11-38 When should CPAP not be used? trained to give CPAP safely.CPAP must not be used in infants with severe NOTE CPAP can be given without a Flow Driver ifrespiratory distress or severe recurrent apnoea. the special nosepiece is available. However, it isThese infants need mechanical ventilation, preferable to use a Flow Driver.especially if they have severe recession andgrunting or need an FiO2 of over 0.6 to keep 11-41 How much CPAP is needed?their SaO2 in the normal range. Usually 4 to 5 cm water pressure is given. ThisCPAP is also not helpful in infants with usually requires a flow rate of 6 to 8 litres perneonatal asphyxia or cyanotic heart disease. minute. The FiO2 should be increased until the NOTE CPAP is very useful after extubation from SaO2 is 86 to 92%. Some infants with recurrent mechanical ventilation and may also be helpful apnoa may need CPAP with air and no added in infants with pneumonia and large ductus oxygen. arteriosus.
  10. 10. 214 NEWBORN CARE11-42 When is CPAP successful? 4. Damage to the nasal mucous membrane or cartilage (pressure necrosis). This is usuallyMost infants on CPAP will soon settle down caused by using prongs that are too big andwithout severe recession or apnoea. The FiO2 do not fit correctly.should fall to below 0.4 with a normal SaO2. 5. Pneumothorax NOTE With successful CPAP the pH should be 6. Abdominal distension and vomiting. This above 7.25 and the PaC02 should be below 7.5 kPa. can be prevented by an open orogastric tube.11-43 Can infants on CPAP be fed? 7. Water collecting in the tubingAn orogastric tube should be inserted and left Most of these complications can be avoidedopen to drain. This prevents CPAP distending with correct care and careful monitoring.the stomach with air. As a result infants onCPAP usually are not given milk feeds but 11-46 When has CPAP failed?require an intravenous infusion. The infant’smouth acts as a natural safety valve if the When CPAP does not correct severe respiratoryCPAP pressure is too high. Therefore the distress, apnoea or hypoxia. Infants with severemouth must not be taped closed. recession, recurrent apnoea or a FiO2 above 0.6 need mechanical ventilation.11-44 Can surfactant be used with CPAP? NOTE Infants with a PaCO2 above 7.5 kPa or pH below 7.25 are in respiratory failure and needCPAP and surfactant are often used together ventilation.in infants with hyaline membrane disease. Thisprevents alveolar collapse and avoids the need 11-47 When can CPAP be stopped?for mechanical ventilation in many of theseinfants. Usually the infant is intubated to give Once the infant is clinically improving thethe surfactant and then extubated and placed FiO2 can be slowly reduced. When the FiO2on CPAP. Infants with severe HMD need reaches 0.25 the CPAP can be slowly reducedsurfactant and mechanical ventilation. in steps of 1 cm water at a time. Stop the CPAP and remove the nose piece when the pressure is less than 2 cm water and the FiO2 is 0.21. Surfactant and CPAP are often used together to It is important to monitor the SaO2 carefully treat infants with mild hyaline membrane disease while weaning an infant off CPAP.11-45 What are the problems with CPAP? CASE STUDY 11. It must be given in a newborn nursery by staff who have all the required equipment A preterm infant is nursed in a closed incubator and are trained in the technique of giving in room air. The doctor asks that the infant’s CPAP correctly. It is dangerous if given by SaO2 be measured. When this is found to be inexperienced staff. In this situation nasal low, she starts extra oxygen via nasal cannulas. cannula or headbox oxygen is safer. The nurse is then asked to record the FiO2.2. Nasal obstruction as the result of secretions or the prongs not being correctly 1. How much oxygen is present in room air? positioned. Warmed humidified oxygen helps to prevent excessive nasal secretions. There is 21% oxygen in room air. Nitrogen Routine nasal suctioning is not needed. forms most of the air we breathe.3. The nasal prongs can be displaced (come out of the nostrils). Attaching the nose piece correctly to the cap is important.
  11. 11. OXYGEN THERAPY 2152. What does SaO2 mean? CASE STUDY 2The SaO2 is the saturation of oxygen inarterial blood, i.e. what percentage of the A 3 day old, term infant has pneumonia in ahaemoglobin in the red cells are saturated level 1 hospital and is nursed in an incubator.(filled) with oxygen. The infant is cyanosed in room air and needs oxygen therapy.3. How is the SaO2 measured? 1. What equipment should be used toWith a pulse oximeter (a saturation monitor) administer the oxygen?which clips onto the infant’s hand or foot. Oxygen could be given via nasal cannulas4. What is the normal range of SaO2 in a or into a perspex head box. Giving oxygennewborn infant? directly into the incubator is unsatisfactory as it uses a lot of oxygen. In addition, high85 to 92% concentrations of oxygen cannot be reached with this method and the amount of oxygen in5. What do you understand by FiO2? the incubator drops if a porthole is opened.The FiO2 is the fraction of oxygen in roomair (how much of air the infant is breathing 2. How should you control the fraction ofis made up of oxygen). The FiO2 of room air oxygen given?is 0.21 (i.e. 21%). As more and more oxygen With an oxygen-air blender or a venture (in ais added to the air the infant receives, the head box).FiO2 will increase. The FiO2 will give you anaccurate measurement of how much oxygen 3. Why should the oxygen or oxygen/airthe infant is breathing in. mixture be humidified?6. How is the FiO2 measured in a head box? Because unhumidified gas is very dry and will irritate the linings of the nose, throat andWith an oxygen monitor. This is better than airways.just reading the percentage oxygen on the air-oxygen blender or venturi and far better than 4. What volume of oxygen/air mixtureusing the reading on the flow meter to guess should be given into the head box?the percentage of oxygen in the inspired air. A flow rate of 5 litres per minute is best. This is7. What is the value of knowing all these measured on the flow meter.measurements? 5. What oxygen sources can be used if theKnowing how much oxygen is being breathed hospital does not have piped oxygen?in and how much oxygen in present in thearterial blood is important information as it Bottled oxygen or an oxygen concentrator.indicates whether there are problems in theinfants lungs and heart. It also helps to assesshow severe the problems are. The more oxygen CASE STUDY 3that is needed to provide a normal saturation,the more severe is the problem. A sick infant with respiratory distress is receiving oxygen via nasal cannulas. The FiO2 is 0.75. Both the tongue and peripheries are pink.
  12. 12. 216 NEWBORN CARE1. What does an FiO2 of 0.75 mean? 1. What do you think about the SaO2 reading?It means that the infant is receiving 75% oxygen. It is too high as the normal range is 86–92%.2. Why should you be unhappy to decide This indicates that this infant is receiving toothe correct FiO2 by simply examining the much oxygen.colour of the infant’s tongue? 2. What is the normal range for the PaO2?Central cyanosis indicates that the infantdoes not have enough oxygen in its red cells The PaO2 should be between 8 and 10 kPaand, therefore, needs a higher FiO2. However, (60–75 mm Hg). Therefore, the reading in thisthe tongue will be pink whether the infant is infant is above the normal range.receiving the correct amount of oxygen or toomuch oxygen. The FiO2 of 0.75 may, therefore, 3. How would you change the managementbe much too high for this infant. of this infant? The FiO2 must be reduced by adjusting the3. How should you determine whether this oxygen/air mixture on the blender. Theinfant is receiving the correct concentration FiO2 should be reduced by 0.05 (5%) everyof oxygen? 15 minutes while watching the SaO2. TheThe SaO2 (saturation of oxygen in arterial FiO2 is correct when the SaO2 falls within theblood) or the PaO2 (partial pressure of oxygen normal range.in arterial blood) must be measured. 4. What is the danger of too much oxygen4. How is the PaO2 measured? in this infant?A blood gas analyser is used to measure the Retinopathy of prematurity. The high PaO2PaO2 on a sample of blood (usually arterial). damages the immature retina and this may cause blindness.CASE STUDY 4 5. What is the greatest danger of giving this infant too little oxygen?An infant, born after 28 weeks gestation, has Brain damagehyaline membrane disease and is receivingoxygen by nasal prongs which give CPAP of 6. What is the advantage of using CPAP?7 mm. The FiO2 is 0.55, the SaO2 is 98% andthe PaO2 is 20 kPa (150 mm Hg). It helps to prevent collapse of the alveoli and reduces the need for ventilation.

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