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Cardiac and behavioral reactivity of the human newborn to facial stimulation eliciting approach and escape responses were compared in order to test the distinction between cardiac orienting and defensive reactions. Each infant received 8 trials each of cheek stimulation (stroking near the mouth) and ear stimulation (pinch on the ear lobe). HR responses to both tactile stimuli were accelerations of different amplitude when motor responses were also present. When no overt behavioral response was observed, stroking on the cheek elicited cardiac deceleration while ear stimulation again elicited acceleration. Thus, cardiac orienting was demonstrated in newborns when a rooting stimulus was presented that did not elicit overt head turning. The HR response to ear stimulation on trials unaccompanied by observed movements was a larger acceleration than to cheek stimulation when movement was present. This finding suggests that movement itself does not produce the observed HR increase, but rather that central processing of the signal value of the stimulus determines both overt and cardiac responding. [ABSTRACT FROM AUTHOR]

The neonatal heart rate (HR) response to brief stimuli has generally been reported to be a monophasic acceleration. In this study brief auditory clicks to 6 neonates elicited, to a significantly greater degree than in non-stimulus conditions: 1) deceleration alone, 2) acceleration alone, and 3) a biphasic response consisting of an initial deceleration and a subsequent acceleration. The data are not yet available which would permit selection among the orienting reflex (OR), defense reflex, startle reflex, and Moro reflex models of these HR responses. With regard to peripheral mechanism, the early decelerative response was probably mediated by increased vagal inhibitory tone. The later accelerative response may have been mediated by one or more of the following mechanisms: decreased vagal inhibitory tone, activation of vagal accelerator fibers, and/or activation of sympathetic accelerator fibers. [ABSTRACT FROM AUTHOR]

Two-second long square wave tones at frequencies of 125 and 1000 Hz and 75 db sound pressure were presented to six newborn infants. Mean heart rates were computed for the 10 sec prior to and the 10 sec following stimulus onset, i.e. the prestimulus and stimulus heart rate values respectively. LIV was shown to operate strongly only in the case of the 125 Hz stimulus. Even for this stimulus, LIV depended upon the state of the infant, showing an appropriate negative correlation between prestimulus and stimulus values in regular sleep and quiet wakefulness but a slightly positive correlation in irregular sleep. In randomly selected control periods, the first 5 sec served as prestimulus values and the second 5 sec as stimulus values. Regression coefficients for these control periods did not differ significantly from those during which the stimulus was actually present. In view of the special conditions required for its demonstration, the generality of Wilder's "law" seems to be seriously questioned. [ABSTRACT FROM AUTHOR]

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Copyright of Medical & Biological Engineering (0025696X) is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

ABSTRACT The distances from the maxillary alveolar margin and external nares to the carina and the vocal folds were measured from chest roentgenograms in 77 patients weighing between 750 gm and 5000 gm. The tip of an endotracheal tube introduced 7 cm beyond the alveolar margin, or 8 cm beyond the external nares, would fall somewhere in the trachea in all patients in this series weighing between 800 gm and 4500 gm. The incidence of misplacement of endotracheal tubes is high (50% in this series). Introduction (or subsequent displacement) of the tube beyond 7 cm (if in the mouth) of 8 cm (if in the nose) should arouse suspicion of misplacement of the tube tip in the right mainstem bronchus. [ABSTRACT FROM AUTHOR]