Neutral neck position

Abstract: Background: Appropriate bag-and-mask ventilation with patent airway is mandatory during induction of general anesthesia. Although the sniffing neck position is a traditionally recommended head and neck position during this critical period, knowledge of the influences of this position on the pharyngeal airway patency is still inadequate. Methods: Total muscle paralysis was induced with general anesthesia in 12 patients with obstructive sleep apnea, eliminating neuromuscular factors contributing to pharyngeal patency. The cross-sectional area of the pharynx was measured endoscopically at different static airway pressures. Comparison of static pressure‐area plot between the neutral and sniffing neck positions allowed assessment of the influence of the neck position change on the mechanical properties of the pharynx. Results: The static pressure‐area curves of the sniffing position were above those of neutral neck position, with increasing maximum cross-sectional area and decreasing the closing pressure at both retropalatal and retroglossal airways. The beneficial effects of the sniffing position were greater in obstructive sleep apnea patients with higher closing pressure and smaller body mass index. Conclusions: Sniffing position structurally improves maintenance of the passive pharyngeal airway in patients with obstructive sleep apnea and may be beneficial for both mask ventilation and tracheal intubation during anesthesia induction. THE sniffing neck position, defined as neck flexion with upper cervical extension, is a traditionally recommended head and neck position for induction of general anesthesia unless contraindicated. Compared with the neutral neck position, the sniffing position significantly improves laryngeal view during direct laryngoscopy, particularly in obese persons. 1,2 In addition to its advantages in direct laryngoscopy, the head and neck position should preferably accomplish patent airway during induction of general anesthesia, assuring appropriate bagand-mask ventilation during the critical period. This is particularly important in obese patients with sleep-disordered breathing (SDB) who have narrow pharyngeal airways and rapid development of hypoxemia as a result of reduced functional residual capacity without proper mask ventilation. 3,4 Surprisingly, knowledge regarding influences of the sniffing neck position on pharyngeal airway patency in anesthetized and paralyzed persons is still inadequate. 5 This prompted us to test a hypothesis that the sniffing position improves pharyngeal airway patency, by studying the influences of this neck position on pharyngeal airway patency in anesthetized and paralyzed patients with SDB, and furthermore, the possible impacts of obesity on mechanical influences.

Abstract: The primary purpose of this exploratory study was to determine if two corrective neck postures, axial extension and neutral neck position, are widely used by physical therapists to relieve neck pain and spasm of the upper trapezius. A random sample of physical therapists in New York, New Jersey, and Puerto Rico were polled by means of a structured questionnaire. Of the 52 respondents, 32 reported that patients with neck pain and spasm of the upper trapezius often assume a forward head position (p < 0.001). A similar number (N = 33) reported that they often used postural training in their treatment of neck pain and spasm of the upper trapezius (p < 0.001). Even though there is no scientific basis for recommending either of the two corrective postures, the study revealed two groups of physical therapists, those who recommend axial extension (N = 21) and those who advocate neutral neck position (N = 25).

Abstract: Purpose The aim is to study the dependence of deformable based auto-segmentation of head and neck organs-at-risks (OAR) on anatomy matching for a single atlas based system and generate an acceptable set of contours. Methods A sample of ten patients in neutral neck position and three atlas sets consisting of ten patients each in different head and neck positions were utilized to generate three scenarios representing poor, average and perfect anatomy matching respectively and auto-segmentation was carried out for each scenario. Brainstem, larynx, mandible, cervical oesophagus, oral cavity, pharyngeal muscles, parotids, spinal cord, and trachea were the structures selected for the study. Automatic and oncologist reference contours were compared using the dice similarity index (DSI), Hausdroff distance and variation in the centre of mass (COM). Results The mean DSI scores for brainstem was good irrespective of the anatomy matching scenarios. The scores for mandible, oral cavity, larynx, parotids, spinal cord, and trachea were unacceptable with poor matching but improved with enhanced bony matching whereas cervical oesophagus and pharyngeal muscles had less than acceptable scores for even perfect matching scenario. HD value and variation in COM decreased with better matching for all the structures. Conclusion Improved anatomy matching resulted in better segmentation. At least a similar setup can help generate an acceptable set of automatic contours in systems employing single atlas method. Automatic contours from average matching scenario were acceptable for most structures. Importance should be given to head and neck position during atlas generation for a single atlas based system.

Abstract: In the previous paper (Enwemeka, Bonet, Ingle, et al. 8:235–239, 1986) we showed that patients with neck pain and spasm of the upper trapezius often assume a forward head position, and that two neck positions, axial extension, and neutral neck position are frequently used by physical therapists to correct this faulty neck posture. Because there is no scientific basis for recommending either of the two corrective neck positions, we simulated the three neck positions in 10 normal adults and compared the integrated electromyography (IEMG) of the upper trapezius to determine if the muscle shows less activity in any of the two corrective positions. The results showed significantly less IEMG of the upper trapezius in each of the two corrective neck positions than in the faulty neck position (p 0.10). The implications and limitations of these findings are discussed along with suggestio...