Date Published: March 22, 2016
Publisher: Public Library of Science
Author(s): Utpal S. Bhalala, Malvi Hemani, Meehir Shah, Barbara Kim, Brian Gu, Angelo Cruz, Priya Arunachalam, Elli Tian, Christine Yu, Joshua Punnoose, Steven Chen, Christopher Petrillo, Alisa Brown, Karina Munoz, Grant Kitchen, Taylor Lam, Thangamadhan Bosemani, Thierry A. G. M. Huisman, Robert H. Allen, Soumyadipta Acharya, Umberto Simeoni.
Head-tilt maneuver assists with achieving airway patency during resuscitation. However, the relationship between angle of head-tilt and airway patency has not been defined. Our objective was to define an optimal head-tilt position for airway patency in neonates (age: 0–28 days) and young infants (age: 29 days–4 months). We performed a retrospective study of head and neck magnetic resonance imaging (MRI) of neonates and infants to define the angle of head-tilt for airway patency. We excluded those with an artificial airway or an airway malformation. We defined head-tilt angle a priori as the angle between occipito-ophisthion line and ophisthion-C7 spinous process line on the sagittal MR images. We evaluated medical records for Hypoxic Ischemic Encephalopathy (HIE) and exposure to sedation during MRI. We analyzed MRI of head and neck regions of 63 children (53 neonates and 10 young infants). Of these 63 children, 17 had evidence of airway obstruction and 46 had a patent airway on MRI. Also, 16/63 had underlying HIE and 47/63 newborn infants had exposure to sedative medications during MRI. In spontaneously breathing and neurologically depressed newborn infants, the head-tilt angle (median ± SD) associated with patent airway (125.3° ± 11.9°) was significantly different from that of blocked airway (108.2° ± 17.1°) (Mann Whitney U-test, p = 0.0045). The logistic regression analysis showed that the proportion of patent airways progressively increased with an increasing head-tilt angle, with > 95% probability of a patent airway at head-tilt angle 144–150°.
Birth asphyxia is responsible for an estimated 717,000 newborn deaths every year, or about 23% of the global burden of newborn deaths . Effective newborn resuscitation is essential in reducing the sequelae of birth asphyxia [2,3]. Resuscitation programs recommend that for those newborn who do not start breathing despite drying and stimulation, positive-pressure ventilation should be initiated within one minute after birth . One of the challenges of positive-pressure ventilation in unconscious or sedated children is a tendency for airway obstruction due to relaxation of airway tone and glossoptosis [5,6]. The head-tilt maneuver for airway patency involves extension of the head at the atlanto-occipital joint and, coupled with the chin-lift maneuver, is a well-described airway maneuver for airway patency during resuscitation [6,7,8]. Though there is well-documented literature on the relationship of the chin-lift maneuver with airway patency, the relationship between the angle of head-tilt and airway patency has not been defined . There are conflicting results of studies on the relationship of head extension and airway patency in adults [6,10,11]. For newborns, the Neonatal Resuscitation Program (NRP) recommends “sniffing position” (neck flexion with upper cervical extension) for airway patency using a roll under the neck to compensate for the large occiput . The Neonatal Life Support (NLS) program recommends positioning the child’s head in a neutral position using a roll under the shoulder to achieve upper airway patency. However, for both newborns and infants, neither the sniffing position nor the neutral head position has been evaluated for airway patency . Also, an improper placement of a roll under the neck or shoulder could potentially jeopardize the airway. Defining angle of head-tilt for airway patency would help clarify the current controversy of the two guidelines related to the head-neck position during neonatal resuscitation. The information may also be used to create a neonatal resuscitation mat with a built-in shoulder-roll to ensure airway patency during resuscitation. Therefore, the goal of our study was to evaluate the relationship between degree of head tilt as measured by sagittal MRI and patency of the airway in a cohort of neonates and young infants who underwent MRI.
We retrospectively studied the MR images of the airway of neonates (age: 0–28 days) and young infants (age: 29 days– 4 months) at our institution. The Johns Hopkins Institutional Review Board (IRB) approved the study. Since it was a retrospective review of MRI of patients in our Johns Hopkins Hospital, informed consent, written or oral, was NOT obtained from the participants. The Johns Hopkins IRB provided waiver of informed consent due to the retrospective nature of the study. The data reported in the manuscript were not analyzed anonymously.
Of the 63 children who were analyzed, 17 had evidence of airway obstruction, 46 had a patent airway on MRI. An obstructed airway was visible as complete occlusion of airway lumen at the level of palate and/or dorsum of tongue (Fig 2). Also, 16/63 had underlying HIE and 47/63 newborn infants had exposure to sedative medications during MRI. A one-sample Kolmogorov-Smirnov test confirmed that the samples were not normally distributed with respect to head-tilt angle. Therefore, we used a Mann-Whitney U test to compare the blocked airway to the patent airway instead of a standard student’s t-test (p < 0.05 as significant). In spontaneously breathing and neurologically depressed newborn infants, the median head-tilt angle associated with patent airway (125.3° ± 11.9°) was significantly different from median head-tilt angle (108.2° ± 17.1°) associated with a blocked airway (p = 0.0045) (Fig 3). The airway diameters (mean ± SD) in spontaneously breathing, sedated children with open airway were 5.8 ± 1.8 mm (AP at palate), 6.3 ± 1.5 mm (AP at dorsum of tongue) and 7.4 ± 2.7 mm (lateral). The Pearson correlation coefficient did not show any correlation between median head-tilt angle of airway patency and either age, gestational age, and weight of the newborn infant (Table 1). The logistic regression model showed that the proportion of patent airways progressively increased with an increasing head-tilt angle (Table 2). There was at least a 95% probability that an airway will be patent between head-tilt angle 144–150° (Fig 4). Pearson's Chi-square test (p = 0.440), deviance test (p = 0.441), and Hosmer-Lemeshow test (p = 0.409) confirmed the goodness-of-fit of the logistic regression model. Airway patency is a cornerstone of neonatal resuscitation. Various head positions and airway maneuvers are described to maintain airway patency during resuscitation in newborn infants. Neither sniffing position (recommended by NRP) nor neutral head position (recommended by NLS) have been evaluated for airway patency in newborns and infants . We hereby describe the MRI findings of airway patency in relation to head tilt position. To our knowledge, this is the first study of quantitative analysis of head-tilt position and airway patency in neurologically depressed neonates and young infants using MRI images. The study findings are clinically relevant for several reasons. It clarifies an unanswered question about head tilt position for airway resuscitation in neonates and young infants and it identifies a specific angle of head-tilt position for future development of a resuscitation device. There are several common problems that interfere with effective neonatal resuscitation, one of which is improper head and neck position . Airway occlusion due to improper head-neck position within the golden minute of neonatal resuscitation potentially contributes to increased neonatal mortality. In several neonatal resuscitation settings, especially in the developing countries, a semi-trained birth attendant may have to independently perform the complex steps of neonatal resuscitation. In such a situation, the complex resuscitation could be simplified by using a device that provides support for the head-tilt position as defined by our study. There is a >95% probability of a patent airway at a head-tilt angle (between occiput-ophisthion-cervical spine) of 144–150° in spontaneously breathing, sedated children between the ages of 0–4 months. The head-tilt angle range of 144–150° for airway patency corresponds to a slightly extended head position.