Neonatal Resuscitation with the Laryngeal Mask Airway in Normal and Low Birth Weight Infants

Maintenance of a clear airway is the primary objective of neonatal resuscitation and is currently achieved via either a face mask or tracheal tube (1). The laryngeal mask airway (LMA) has a potential role in neonatal resuscitation as an alternative to the face mask and for difficult airway management (2), but published data are limited. Paterson et al. (3) described its successful use in 21 neonates weighing >2.5 kg. Margaria et al. (4) showed that oxygen saturation increased more rapidly with the LMA than with the face mask in 100 neonates, but demographic details were lacking. The size 1 LMA is currently recommended for infants <5 kg (5), but its use in neonates <2.5 kg has only been reported anecdotally (6). The objective of this prospective observational study was to evaluate LMA use by a single pediatric resident in normal and low birth weight (<2.5 kg) neonates requiring positive pressure ventilation (PPV) during resuscitation. Methods With ethics committee approval, we studied LMA use for neonatal resuscitation for 5 yr. In our institute, the LMA has been a standard of care for neonatal resuscitation since 1994. After delivery, neonates were transferred to a standard neonatal resuscitation cart and were included in the study if they required PPV for apnea or a heart rate <100 bpm (7). Clinical assessment of heart rate, respiratory effort, and skin color (under a constant level of light) was made continually once the neonate was on the resuscitation cart. Heart rate was determined by palpation of the apex beat and repeatedly counting beats in 3-s blocks (if the count was <5, heart rate was <100 bpm). Neonates with meconium-stained fluid underwent laryngoscopy before PPV was commenced and were excluded if they had evidence of meconium aspiration. All insertions were performed by one of the authors (DG). Training included five uses of the LMA in neonatal resuscitation. The size 1 LMA was inserted and fixed using the recommended technique (5). No lubrication was used due to the wetness of the neonatal oropharynx. The LMA cuff was inflated with 1–4 mL of air, held in place manually, and connected to an anesthesia breathing system with 100% oxygen at a flow rate of 12 L/min. PPV at a rate of 60–80 breaths/min was commenced while the neonate was dried and warmed by an assistant. Airway pressures were limited to 40 cm H2O. The airway pressure at which an audible leak occurred was recorded (8). Gastric insufflation was assessed by epigastric stethoscopy. If adequate chest expansion with PPV was not obtained after two insertion attempts, either a face mask or a tracheal tube was to be used. When spontaneous breathing commenced, continuous positive airway pressure at 5–10 cm H2O was provided until breathing became regular. The LMA was removed when the neonate rejected it. If there was any subsequent deterioration in heart rate or respiratory effort, the LMA was reinserted. If the neonate required PPV for >15 min, the LMA was removed and the trachea intubated. The following data were collected by assisting midwives trained in the study protocol: mode of delivery; delivery to resuscitation time (umbilicus cut to start of resuscitation); the number of insertion attempts; audible leak pressure; and the time from start of resuscitation to achieve 1) adequate chest expansion, 2) a heart rate ≥100 bpm, 3) a pink trunk, 4) regular breathing, and 5) LMA removal. Apgar scores were recorded 1 and 5 min postdelivery. The number of neonates requiring LMA reinsertion or intubation was recorded. Time zero for start of resuscitation was recorded from when the LMA was picked up for the first insertion attempt. Statistical analysis was performed by using a paired t-test, Friedman’s two-way analysis of variance, and a χ2 test. Significance was taken as P < 0.05. Results The investigator attended 689 deliveries over the study period. One hundred thirty neonates were apneic or had a heart rate <100 bpm at delivery. Thirty-five had meconium-stained fluid. Twenty-six had evidence of meconium aspiration and were intubated tracheally. One hundred four neonates met the inclusion criteria. Comparative data are presented in Table 1. One hundred three (99%) neonates were successfully resuscitated. Low birth weight neonates were more frequently premature and required more PPV >15 min, but there were no other differences between the groups. Six neonates delivered by cesarean section under general anesthesia required LMA reinsertion after successful resuscitation due to central hypoventilation. Six neonates resuscitated with the LMA subsequently developed respiratory distress syndrome 30–120 min postdelivery and required nasopharyngeal continuous positive airway pressure (n = 2), tracheal intubation for PPV, and/or administration of surfactant (n = 4). There was no gastric insufflation or pneumothoraces. In one 3.5-kg neonate with no meconium staining, LMA insertion was readily achieved, but PPV was impossible. The LMA was immediately removed and the trachea intubated. PPV remained impossible, and this unexpected stillbirth was found to have severe meconium aspiration at postmortem. Table 1: Comparative Data for Normal and Low Birth Weight Neonates Resuscitated with the LMADiscussion Paterson et al. (3) showed that a clear airway could be obtained with the LMA in nine seconds and that oxygenation could be restored in 30 seconds. Margaria et al. (4) showed that insertion time was two seconds and that oxygen saturation was >90% within five minutes. Our results support these findings and show that the LMA may be used in low birth weight neonates, including neonates weighing 1–1.5 kg. Our values for audible leak pressure were similar to those reported by Paterson et al. (3), at approximately 23 cm H2O. Most apneic neonates with normal lungs require <25 cm H2O for initial lung expansion (9). The LMA may be unsuitable for PPV in neonates who have low compliance lung pathology because higher airway pressures may be required. However, the low-pressure seal formed with the pharynx will protect normal lungs from barotrauma. The LMA is unsuitable for neonates with meconium aspiration because a suction catheter cannot be reliably passed into the lungs without fiberoptic guidance, and there may be coexisting lung pathology. We conclude that the LMA can be used for PPV in normal and low birth weight neonates requiring resuscitation. Its reliability when used by multiple users or inexperienced personnel is unknown.