AUSTRALIAN RESUSCITATION COUNCIL GUIDELINE 13.4 AIRWAY MANAGEMENT AND MASK VENTILATION OF THE NEWBORN INFANT

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1 GUIDELINE 13.4 AIRWAY MANAGEMENT AND MASK VENTILATION OF THE NEWBORN INFANT EFFECTIVE VENTILATION IS THE KEY TO SUCCESSFUL NEONATAL RESUSCITATION All staff involved in the delivery and care of newborn infants must be familiar with the ventilation equipment and be proficient in basic neonatal resuscitation techniques. POSITIONING AND THE AIRWAY The newborn infant should be placed on his or her back with the head in a neutral or slightly extended position. If respiratory efforts are present but not producing effective ventilation (the heart rate does not rise above 100/min) the airway may be obstructed and the head should be positioned in slight extension (the sniffing position). Mouth and Pharyngeal Suction Normal newborn infants do not require suctioning of the nose, mouth or pharynx after delivery. They clear their airway very effectively. If secretions may be obstructing the airway they can be cleared with a large bore suction catheter (10 to 12 Fg). However, pharyngeal suction can cause laryngeal spasm, trauma to the soft tissues, bradycardia, and delay the onset of spontaneous breathing (1). Therefore, any pharyngeal suction should be done with care. If it is unlikely that meconium or blood has been inhaled, suction is rarely needed. If used it should be limited to 5 seconds and not more than 5 cm from the lips in a term infant. The negative pressure used should not exceed 100 mm Hg (13 kpa, 133 cm H 2 O, 1.9 Psi). Management of the airway in the presence of meconium stained liquor Intrapartum pharyngeal suction Sucking out the infant s mouth and pharynx, before the delivery of the shoulders, makes no difference to the outcome of babies with meconium stained liquor and is no longer recommended (2;3). Guideline 13.4 Page 1 of 9

2 Endotracheal suction Routine endotracheal intubation of babies who have meconium stained liquor, and who are vigorous, is not recommended because it does not alter their outcome and may cause harm (4;5). If the amniotic fluid contains thick meconium, and the infant has absent or depressed respirations, and decreased muscle tone, sucking the meconium from the mouth and pharynx should be carried out immediately with direct laryngoscopy (under direct vision) and, if needed, be followed by intubation and suction of the trachea. This must be brief and not compromise the infant. TACTILE STIMULATION Drying and stimulation are both assessment and resuscitative interventions. If the infant fails to establish spontaneous and effective respirations with an increased heart rate to more than 100/min positive pressure ventilation will be required. POSITIVE PRESSURE VENTILATION Positive pressure ventilation should be started if the infant remains apnoeic after stimulation, or the breathing is inadequate, and the heart rate is less than 100 /min. The main effect of adequate ventilation is a prompt improvement in heart rate which is then sustained. Chest wall movement should be assessed if the heart rate does not improve. If there is little or no visible chest wall movement the technique of ventilation should be improved by assuring the face mask fits well on the face with minimal leak so that the chest wall is then seen to increase with inflation. If that is ineffective the inflating pressure must be increased until chest wall movement is seen and the heart rate increases. MANUAL VENTILATION DEVICES A self-inflating bag, a flow-inflating bag or a T-piece device are all acceptable devices which can be used to ventilate newborn infants either via a facemask or endotracheal tube. Self inflating bags Following compression, a self-inflating bag 1 reexpands due to its elastic recoil. It does not depend on a gas source for inflation although one may be attached for the delivery of oxygen. The automatic re-expansion of the self-inflating bag, effective operation without a pressurised gas supply and the simplicity of use, and portability, are the greatest assets of this device. It is difficult to deliver consistent inflating pressures with a self-inflating bag. The maximum pressure is limited by a pressure-release valve, which is factory set to activate at approximately 40 cm H 2 O and can be over-ridden should a higher pressure be required to achieve chest wall movement. These valves have been demonstrated to activate at inconsistent and wide range of pressures (6). Self-inflating bags do not provide a positive end expiratory pressure (PEEP), though a PEEP valve may be fitted to certain models. 1 This diagram is printed with the permission of the American Academy of Pediatrics Neonatal Resuscitation Program Guideline 13.4 Page 2 of 9

3 Self-inflating bags cannot be used to deliver a sustained inflation longer than about one second (7). Self inflating bags cannot deliver 100% oxygen unless a reservoir bag is attached (8). The flow of oxygen delivered to the infant is unreliable (9;10) and these devices should not be used to deliver free flow oxygen when the mask is tight on the face. The 240 ml self-inflating neonatal resuscitation bag is the most appropriate size for ventilating new born infants of all sizes, despite some suggestions to the contrary (7). This is because the tidal volume is approximately 5 10 ml/kg body weight. A volume of 240 ml, even when compressed, should be more than adequate to inflate any newborn s lungs. If ventilation is inadequate with a bag of this size it is (most likely to be) due to a very large leak between the mask and the infant s face. The other causes are: faulty equipment, stiff lungs, locked airway etc Flow-inflating bags 2 A flow-inflating (or anaesthesia) bag requires a compressed gas source to inflate the bag when in use. Large leaks at the face mask, or too low a flow, will result in collapse of the bag and inability to deliver any tidal volume. While this makes it more difficult to use, it is an advantage as the operator is immediately aware that the mask may not be properly placed on the baby s face. These devices can produce a very high pressure and should always be used with a pressure gauge and blowoff valve in the circuit. They can be difficult to use without training and experience. An expiratory pressure (CPAP or PEEP) can be provided by controlling the pressure in the bag by adjusting the flow of gas into the bag and the rate of gas escape at the outlet valve from the bag. However, the pressures can vary considerably and may reach dangerously high levels. Flow-inflating bags can be used to deliver sustained inflations. T-piece resuscitation devices With a T-piece device 3, gas flows into a facemask or ETT through an inlet arm. Inflation is achieved by interrupting the escape of gas through an outlet hole using a thumb or finger so that the pressure rises and is displayed by a manometer. A variable release valve is adjusted to limit the applied peak inflating pressure (PIP). The inflation time is altered by varying the duration of occlusion of the outlet hole. CPAP or PEEP is delivered automatically and the pressure varied by adjusting the outlet valve. This controls the rate of escape of gas when the outlet is not occluded (i.e. in expiration) and generates a set level PEEP or CPAP. The level of PEEP or CPAP can also be adjusted by altering the flow into the system. 2 This diagram is printed with the permission of the American Academy of Pediatrics Neonatal Resuscitation Program 3 This diagram is printed with the permission of Fisher and Paykel, Auckland, New Zealand. Guideline 13.4 Page 3 of 9

4 Before any resuscitation, check the equipment: 1) Self inflating bag a) check the device is put together correctly b) ensure a reservoir bag is attached c) if attached to a gas supply set the flow to 8 L/min (it does not need a gas supply) d) obstruct the open end, where the face mask fits, squeeze the bag to see that a pressure is achieved and the pressure blow off valve opens e) at the end of inflation check that the bag reinflates quickly 2) Flow inflating bag a) Check the device is put together correctly and ensure that a manometer and blow-off valve are attached b) Set the gas flow to 8 L/min (these must have a gas supply) c) Obstruct the open end where the face mask fits, see that the bag fills quickly d) Squeeze the bag and see that a pressure is achieved and the pressure blow off valve opens when the bag is squeezed e) At the end of inflation, when not being squeezed, see that the bag reinflates quickly 3) T piece device a) Connect a gas supply to the gas inlet port b) Connect the patient circuit, with T-piece, to the gas outlet port c) Adjust gas flow to 8 L/min (set desired oxygen concentration on the blender if used) d) Obstruct the open end, where the face mask fits e) Test the Maximum Pressure Relief Valve by occluding the outlet aperture and turning the PIP clockwise. The maximum pressure should be set at 50 cm H 2 O f) Set desired PIP by occluding the outlet aperture and turning the inspiratory control knob until the required pressure is shown on the manometer (usually about 30 cm H 2 O) g) Take the finger off the outlet aperture and set the PEEP by twisting the PEEP valve to give the desired PEEP (5 to 8 cm H 2 O) h) Remove the test lung and fit an appropriate sized face mask i) Ventilate the newborn infant by placing a finger over the outlet aperture and removing it. This is done about 60 times a minute with an inspiratory time of about 0.5 seconds FACE MASKS The appropriate size of face mask must seal around the mouth and nose but not cover the eyes or overlap the chin. Therefore, a range of sizes must be available for different sized babies. Masks with a cushioned rim are preferable to masks without one (11). With bag-mask ventilation it can be difficult to establish and maintain a good seal between the mask and the infant s face (12) and so it cannot be assumed that just because the mask is on the face there is a good seal. CPAP OR PEEP DURING RESUSCITATION CPAP and PEEP have been shown to be very effective at improving lung volume, reducing oxygen requirements and reducing the incidence of apnoea in premature babies with respiratory distress syndrome (13). There are no randomised controlled trials to show that the use of CPAP or PEEP will improve the outcome of premature babies when used during resuscitation. Guideline 13.4 Page 4 of 9

5 However, there is accumulating evidence that it is beneficial and no evidence of harm when used with babies with stiff lungs (14). Therefore CPAP or PEEP (at least 5 cm H 2 O) should be considered when resuscitating very premature infants to assist their lung expansion, help establish a functional residual capacity and improve oxygenation. THE TECHNIQUE OF MASK VENTILATION: 1) Ensure the airway is open 4 : a) adjust head/neck position to open the airway b) open the mouth slightly, c) clear the airway of meconium or blood if it is present, 2) Inflate the lungs with sufficient pressure and volume that the chest and upper abdomen move slightly. The chest wall movement should equal that seen in normal quiet respiration. 3) The ventilation rate should be about 40 to 60 inflations per minute. 4) What to do if the chest does not move with inflation: a) re-adjust the head-neck position b) ensure the gas flow is turned on and at 8 L/min c) improve the seal between mask and face d) check for a leak in the circuit e) increase the inflation pressure until the chest moves with each inflation. Higher inflation pressures may be required to open the lungs during the first few inflations than for subsequent inflations, particularly in very premature infants who have not made any respiratory effort. An infant who gasps will be easier to ventilate, with lower pressures, than an infant who has never breathed. ASSESSING THE EFFECTIVENESS OF VENTILATION The effectiveness of ventilation is confirmed by observing three things; 1. increase in the heart rate above 100/min 2. a rise of the chest and upper abdomen with each inflation. 3. the baby beginning to look pink If the chest and abdomen do not rise with each inflation, or the heart rate does not increase above 100 beats per minute, the technique of ventilation needs to be improved. Tracheal intubation should be considered if ventilation via a face-mask is ineffective. 4 This diagram is printed with the permission of the American Academy of Pediatrics Neonatal Resuscitation Program Guideline 13.4 Page 5 of 9

6 MOUTH-TO-MOUTH/NOSE AND MOUTH-TO-MASK VENTILATION Where neonatal inflation devices are not available, rescue breathing by mouth-to-mouth-andnose ventilation should be used (15). Resuscitators who are unable to achieve an air tight seal over the mouth and nose of an infant should use a mouth-to-nose technique (16). To decrease the risk of infection to the resuscitator, maternal blood and other body fluids should first be wiped from the face of the infant. The rescuer should then apply their mouth over the mouth and nose of the infant and give small puffs at a rate of breaths per minute to produce a small rise and fall of the chest until the baby improves. Devices for delivering mouth-to-mask resuscitation for neonates are available (17;18). OXYGEN OR AIR FOR RESUSCITATION Several studies have raised concerns about the potential adverse effects of 100% oxygen during resuscitation of new born infants, particularly very premature infants (19-23). Metaanalysis of randomised controlled trials of neonatal resuscitation with air or 100% oxygen have shown a significant reduction in mortality and no evidence of harm in infants resuscitated with air compared with 100% oxygen (24). However, there are some methodological concerns about these studies and the results should be interpreted with caution. Further research is required to determine the optimal concentration of oxygen for resuscitating new born infants. At present the best available evidence suggests that air should be used initially with supplemental oxygen reserved for infants whose condition does not improve during first minutes of life. If a supply of medical air is not available oxygen should be used. Although experts have suggested that pulse oximetry be used to titrate the concentration of supplemental oxygen against an infant s requirements (25;26) there is insufficient evidence to recommend this technique at the moment. In all cases, the first priority is to ensure adequate inflation of the lungs, followed by attention to the desired concentration of inspired oxygen if needed. Guideline 13.4 Page 6 of 9

7 Diagram illustrating the assessment for resuscitation and subsequent management of a newborn baby in the absence of meconium Birth Breathing or crying? Good muscle tone? No Yes Routine care: Dry the baby Provide warmth Clear the airway only if needed Assess breathing, colour and heart rate Dry and stimulate Position the head and neck to open the airway Provide warmth Assess breathing and heart rate * If heart rate <100/min or inadequate breathing If baby is breathing, heart rate is >100/min and beginning to look pink then give routine care and observations appropriate for gestation Give positive pressure ventilation until heart rate >100 and infant breathing* Inadequate breathing and heart rate <60/min* Assess adequacy of ventilation and improve if possible. If heart rate does not increase >60/min Give chest compressions with positive pressure ventilation at 3:1 If heart rate still does not increase > 60/min reassess ventilation technique* Give adrenaline May also need to give IV fluids Guideline 13.4 Page 7 of 9 * endotracheal intubation may be considered at several stages

8 REFERENCES 1. Cordero L, Jr., Hon EH. Neonatal bradycardia following nasopharyngeal stimulation. J Pediatr 1971; 78(3): Falciglia HS, Henderschott C, Potter P, Helmchen R. Does DeLee suction at the perineum prevent meconium aspiration syndrome? Am J Obstet Gynecol 1992; 167(5): Vain NE, Szyld EG, Prudent LM, Wiswell TE, Aguilar AM, Vivas NI. Oropharyngeal and nasopharyngeal suctioning of meconium-stained neonates before delivery of their shoulders: multicentre, randomised controlled trial. Lancet 2004; 364(9434): Wiswell TE, Gannon CM, Jacob J, Goldsmith L, Szyld E, Weiss K et al. Delivery room management of the apparently vigorous meconium-stained neonate: results of the multicenter, international collaborative trial. Ped 2000; 105(1 Pt 1): Liu WF, Harrington T. The need for delivery room intubation of thin meconium in the low-risk newborn: a clinical trial. Am J Perinatol 1998; 15(12): Ganga-Zandzou PS, Diependaele JF, Storme L, Riou Y, Klosowski S, Rakza T et al. [Is Ambu ventilation of newborn infants a simple question of finger-touch?]. Arch Pediatr 1996; 3(12): Field D, Milner AD, Hopkin IE. Efficiency of manual resuscitators at birth. Arch Dis Child 1986; 61: Finer NN, Barrington K, Al-Fadley FA, Peters KL. Limitations of self-inflating resuscitators. Ped 1986; 77: Carter BG, Fairbank B, Tibballs J, Hochmann M, Osborne A. Oxygen delivery using self-inflating resuscitation bags. Pediatr Crit Care Med 2005; 6(2): Martell RJ, Soder CM. Laerdal infant resuscitators are unreliable as free-flow oxygen delivery devices. Am J Perinatol 1997; 14(6): Palme C, Nystrom B, Tunell R. An Evaluation of the Efficiency of Face Masks in the Resuscitation of Newborn Infants. The Lancet 1985; O'Donnell CP, Davis PG, Lau R, Dargaville PA, Doyle LW, Morley CJ. Neonatal resuscitation 2: An evaluation of manual ventilation devices and face masks. Arch Dis Child Fetal Neonatal Ed Morley CJ. Continuous Distending Pressure. Arch Dis Child Fetal Neonatal Ed 1999; 81:F152-F Aly H, Massaro AN, Patel K, El Mohandes AA. Is it safer to intubate premature infants in the delivery room? Pediatrics 2005; 115(6): Part 6: Paediatric basic and advanced life support. Resuscitation 2005; 67(2-3): Tonkin SL, Davis SL, Gunn TR. Nasal route for infant resuscitation by mothers. Lancet 1995; 345: Milner AD, Stokes GM, Tunell R, McKeugh M, Martin H. Laboratory assessment of Laerdal mouth tube mask prototype resuscitation device. Med Biol Eng Comput 1992; 30(1): Massawe A, Kilewo C, Irani S, Verma RJ, Chakrapam AB, Ribbe T et al. Assessment of mouth-to-mask ventilation in resuscitation of asphyxic newborn babies. A pilot study. Trop Med Int Health 1996; 1(6): Guideline 13.4 Page 8 of 9

9 19. Solas AB, Kutzsche S, Vinje M, Saugstad OD. Cerebral hypoxemia-ischemia and reoxygenation with 21% or 100% oxygen in newborn piglets: effects on extracellular levels of excitatory amino acids and microcirculation. Pediatr Crit Care Med 2001; 2(4): Solas AB, Munkeby BH, Saugstad OD. Comparison of short- and long-duration oxygen treatment after cerebral asphyxia in newborn piglets. Pediatr Res 2004; 56(1): Solas AB, Kalous P, Saugstad OD. Reoxygenation with 100 or 21% oxygen after cerebral hypoxemia-ischemia-hypercapnia in newborn piglets. Biol Neonate 2004; 85(2): Huang CC, Yonetani M, Lajevardi N, Delivoria-Papadopoulos M, Wilson DF, Pastuszko A. Comparison of postasphyxial resuscitation with 100% and 21% oxygen on cortical oxygen pressure and striatal dopamine metabolism in newborn piglets. J Neurochem 1995; 64(1): Lundstrom KE, Pryds O, Greisen G. Oxygen at birth and prolonged cerebral vasoconstriction in preterm infants. Arch Dis Child Fetal Neonatal Ed 1995; 73(2):F81- F Davis PG, Tan A, O'Donnell CP, Schulze A. Resuscitation of newborn infants with 100% oxygen or air: a systematic review and meta-analysis. Lancet 2004; 364(9442): Rao R, Ramji S. Pulse oximetry in asphyxiated newborns in the delivery room. Indian Pediatr 2001; 38(7): Milner AD. Resuscitation at birth. Eur J Pediatr 1998; 157(7): Guideline 13.4 Page 9 of 9