Asphyxia is the most common disease of newborns and the main cause of neonatal death and disability. According to 2003 statistics, the neonatal mortality rate was 18.01‰, of which neonatal asphyxia death accounted for 20.8%. In recent years, the incidence and mortality rate of neonatal asphyxia in China has decreased significantly due to the enhanced cooperation between obstetrics and pediatrics and the improvement of pediatric resuscitation techniques. However, surveys in some regions show that standardized methods of neonatal asphyxia resuscitation have not yet been implemented, and problems such as poor cooperation between obstetrics and pediatrics, mainly “empirical” resuscitation, and even the use of respiratory stimulants still exist. In order to further improve the treatment of neonatal asphyxia, it is necessary to standardize the resuscitation techniques and strengthen the standard procedures, which is an area in urgent need of improvement.
Concept 1: Obstetrics and pediatrics should cooperate more
In the process of neonatal asphyxia resuscitation, the cooperation between obstetrics and pediatrics should be strengthened to bring into play the team spirit and work together to protect the fetus to complete a smooth transition to the newborn. Before the delivery of a high-risk woman, pediatricians should also participate in the pre-delivery or pre-surgical discussion, and wait at the delivery bed for delivery and participate in asphyxia resuscitation.
Concept 2: Establish a proper assessment philosophy to guide resuscitation
Resuscitators should make a decisive assessment and decision about the symptoms presented by the newborn according to the neonatal asphyxia resuscitation flow chart (Figure 1).
All newborns are born with only two conditions, i.e., clear amniotic fluid or contaminated amniotic fluid and meconium, and the resuscitator must keep in mind what conditions are encountered and what assessment is done. If the birth is followed by drying or suctioning without assessment, it goes against the philosophy of the guidelines. If assessment is done after positive pressure ventilation, only the heart rate should be assessed, using a heart rate of 60 beats/min as the cut-off; if <60 beats/min, further chest compressions, etc., should be performed. Positive pressure artificial respiration is the primary measure to relieve apnea and bradycardia, and an increased heart rate is the primary indicator of successful positive pressure artificial respiration. Table 1 shows three different methods of assessment.
Concept 3: Oxygen impairment in neonates, especially in preterm infants, should be reduced
In terms of oxygen use (1) full-term neonates: when the child is cyanotic or requires positive pressure ventilation during resuscitation, 100% pure oxygen should be given. Some researchers believe that resuscitation with less than 100% oxygen may also be successful; if resuscitation with less than 100% concentration of oxygen does not improve within 90s after birth, the oxygen concentration should be increased to 100%; when there is no oxygen source, air oxygen can be used for positive pressure ventilation. (2) For small preterm infants (<32 weeks), pulse oximetry monitoring should be performed during resuscitation. When performing positive pressure ventilation, the oxygen concentration should be between 21% and 100%, and it is uncertain which specific oxygen concentration is appropriate to start with; adjust the oxygen concentration so that the oxygen saturation gradually increases to 90%, and when the oxygen saturation exceeds 95%, the oxygen concentration needs to be reduced; there is no high-level evidence that it is harmful to give brief 100% oxygen to preterm infants during resuscitation.
The time of oxygen administration is delayed from “initial resuscitation” to the presence of persistent cyanosis requiring positive pressure artificial respiration (see Figure 1). In China, we use an automatic inflatable balloon, and the oxygen storage bag or tube of the balloon is removed during resuscitation of preterm infants to obtain 40% oxygen concentration, which is suitable as the initial oxygen concentration of preterm infants and should be promoted to the primary level.
Oxygen concentration A meta-analysis of resuscitation of asphyxiated neonates with air or pure oxygen by Dr. Saugstad in Norway showed that 21% oxygen was better than pure oxygen. in another review, Saugstad pointed out that the use of pure oxygen should be avoided in the initial resuscitation of neonates, which may be associated with increased neonatal mortality (about 40%), myocardial and renal damage, and delayed recovery. However, current international and national guidelines for neonatal asphyxia resuscitation still recommend 100% oxygen, and no adverse prognosis has been reported for brief periods of pure oxygen.
Concept 4: Four strategies for neonatal ventilation
Strategy 1 Apply positive end-expiratory pressure (PEEP) or continuous positive airway pressure (CPAP) after resuscitation in preterm infants.
Strategy 2 Application of PEEP protects against lung injury and improves lung compliance and gas exchange.
Strategy 3 The majority of preterm infants with apnea can be initially ventilated with 20-25 cmH2O positive pressure. Higher pressures are needed if the preterm infant requires rapid improvement in heart rate or if no thoracic heave is seen. The use of 30-40 cmH2O positive pressure for the first few breaths is also not recommended for full-term infants, and the pressure should be increased only if there is no improvement with 20 cmH2O.
Excessive CPAP can restrict venous return to the head or cause pneumothorax, increase the incidence of intraventricular hemorrhage, and impair cardiac function by decreasing return blood volume. The European Guidelines for the Prevention and Treatment of Neonatal Respiratory Distress Syndrome suggest that for very low or ultra-low birth weight infants who require surface active substances (PS) after resuscitation, “tracheal intubation – PS – nasal CPAP after extubation” can be performed by the INSURE technique, which can This technique has been clinically used to avoid mechanical ventilation.
The choice of ventilation equipment should pay attention to: (1) adjustable pressure (can provide a constant maximum inspiratory pressure PIP and positive end-expiratory pressure PEEP) T-shaped combination (T-piece) artificial resuscitation device, can be effectively used for neonates, especially premature infants mask or tracheal tube – balloon positive pressure ventilation. (2) The laryngeal mask airway will provide effective ventilation when mask ventilation is ineffective and when tracheal intubation has failed or is not possible.
Concept 5: The use of “meconium suction tube” for endotracheal suctioning of meconium should be promoted
1. The concept of “viable” and “non-viable” should be introduced to determine whether a newborn needs endotracheal suctioning of meconium. If the neonate is viable (regular breathing or loud crying, good muscle tone, heart rate >100 beats/min), endotracheal suction of meconium is not needed; if the neonate is not viable (1 of 3 is not good), the neonate should be immediately placed in an open warmer in an upright position (can not be dried first), transoral tracheal intubation of meconium from the trachea, after suction, complete the initial resuscitation in the drying and stimulation steps, and then assess Then assess respiration, heart rate and skin color, and decide whether positive pressure ventilation is needed.
2. Use one end of the meconium suction tube to connect directly to the tracheal tube connector, and the other end to connect to the low-pressure suction device. During suctioning, the resuscitator fixes the tracheal tube to the newborn’s palate with the right index finger, and presses the hand control port of the meconium suction tube with the left index finger to generate negative pressure when suctioning, and withdraws the tracheal tube while retreating the tracheal tube after 3-5s. If repeated intubation is needed, suction should be applied again. The application of meconium suction tube should be promoted to change the current method of multiple flushing of the tracheal suction tube in China.
3. For neonates who have been contaminated with meconium, oral and nasal suctioning should be routinely performed, and the use of meconium suction tubes is no longer recommended. Argentina et al. found no difference in the incidence of meconium aspiration syndrome, the need for artificial respiration, treatment period and mortality through a clinical multicenter randomized controlled meta-analysis, thus eliminating oropharyngeal suctioning before tracheal intubation. However, if the vocal cavity is found to be blocked by a large amount of meconium during tracheal intubation, an F10 or F12 suction tube can be used to first suction the meconium blocking the vocal cavity before inserting the tracheal tube.
Concept 6: Blood glucose should be monitored after resuscitation
After resuscitation of neonatal asphyxia, special attention should be paid to the detection of hypoglycemia, the incidence of which is 20% to 30%. The symptoms of hypoglycemia in newborns are atypical or asymptomatic, and a few of them show symptoms, such as low response, weak cry, refusal of milk, hypotonia, pallor, hypothermia, irregular breathing, pause, cyanosis, etc. In severe cases, tremors, convulsions, coma, etc. Persistent hypoglycemia can cause serious central neuropathy, resulting in neonatal mental retardation, cerebral palsy and other neurological sequelae. Timely testing of blood glucose can make a clear diagnosis, therefore, maintain blood glucose at 3.3 to 4.4 mmol/L to prevent brain damage caused by hypoglycemia.
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Temperature management of newborns
Premature infants who are kept warm <32 weeks should be wrapped below the neck in plastic bags or plastic cling film (heat-proof for food) and then placed on a conventional radiant heat table to significantly improve their body temperature. After resuscitation preterm infants were removed from the plastic bag to complete steps such as initial resuscitation.
Mathew et al. compared the effect of conventional and plastic bag warming in ultra-low birth weight infants (≤28 W); the mean temperature was higher in the plastic bag group than in the conventional group; the pH was significantly lower in the conventional group in the first 6 h of birth; and the oxygen requirement was greatly increased in the conventional group in the first 24 h after birth, 82.9%, compared with only 43.3% in the plastic bag group. The authors concluded that plastic bag insulation prevents heat loss and is a simple and effective intervention to prevent hypothermia and early acidosis in preterm infants in the delivery room.
Avoiding hyperthermia High body temperature during and after ischemia is associated with brain injury, and neonates requiring resuscitation should be resuscitated to achieve normothermia, and medically induced hyperthermia in resuscitated neonates should be avoided.
Cerebral subhypothermia There is not enough information to suspect that systemic or selective cerebral subhypothermia is routinely recommended after resuscitation of asphyxiated neonates.
Medications used in neonatal asphyxia resuscitation
Epinephrine is recommended in intravenous doses (umbilical vein catheter or umbilical vein puncture preferred); larger doses, up to 0.1 mg/kg (1:10,000 ml/kg), should be administered intratracheally.
Barber retrospectively analyzed a group of 44 cases that had received endotracheal epinephrine (dose 0.01-0.03 mg/kg) in the delivery room.) Normal circulation was restored in only 14 cases (32%) after administration, and in 23 of the remaining 30 cases (77%) ineffective administration was changed to intravenous administration before normal circulation was restored.
Naloxone Naloxone should not be used as an initial resuscitation drug unless two indications are present: (i) heart rate and skin color recover after 30 s of artificial positive pressure breathing, but breathing is still suppressed; (ii) the pregnant woman has used hyperlentin within 4 h before delivery. It is mostly administered intravenously or intramuscularly. Intratracheal administration is not recommended, and the current recommended dose is still 0.1 mg/kg per dose.