ABSTRACT
Objective To verify the feasibility of discriminating tissue types in the anterior approach of the cervical spine by the Electrical impedance (EI) and decrease the rate of severe complications.Methods Six New Zealand white rabbits and 6 mini-pigs were performed standard anterior cervical surgery.The esophagus,carotid artery,tracheal cartilage,annular ligaments of trachea,longus colli muscle and anterior longitudinal ligament are classified as the prevertebral group;The cortical bone,cancellous bone,anulus fibrosus and nucleus pulposus are classified as the vertebral group.Once all the tissues were exposed completely,over the frequency range of 200-3 000 kHz (the frequency points were 200 kHz,400 kHz,600 kHz,800 kHz,1 000 kHz,2 000 kHz,3 000 kHz),the in vivo EI of prevertebral group and vertebral group were measured by a probe and a precision inductance-capacitance-resistance (LCR) meter;then the data were analyzed with IBM SPSS Statistics 22 software.At every frequency,Kruskal-Wallis test followed by all pairwise multiple comparisons was applied for all the four groups (the prevertebral group of rabbits,the vertebral group of rabbits,the prevertebral group of mini-pigs,and the vertebral group of mini-pigs),respectively.P values ＜ 0.05 were considered statistically significant.Results At every frequency,the results of Kruskal-Wallis test for all the four groups were significant,and the results of multiple comparisons were as follows.(1) In both miniature experimental animals and large experimental animals,the EI of the vertebral group tissues was significantly different at every investigated frequency (multiple comparisons).(2) In the miniature experimental animals,the EI between longus colli muscle and esophagus,carotid artery and annular ligaments of trachea,and tracheal cartilage and anterior longitudinal ligament had no significant difference at any frequency (multiple comparisons);significant difference could not be detected in the EI between anterior longitudinal ligament and annular ligaments of trachea at the frequencies of 2000-3 000 kHz (multiple comparisonsk) and could be detected at the frequencies of 200-1 000 kHz (multiple comparisons);for comparison of all other paired tissues of prevertebral group there were significant differences at all frequencies (multiple comparisonsk).(3) In the large experimental animals,the EI between longus colli muscle and esophagus,carotid artery and annular ligaments of trachea,and tracheal cartilage and anterior longitudinal ligament had no significant difference at any frequency (multiple comparisons),the same was true for the EI between annular ligaments of trachea and esophagus,carotid artery and anterior longitudinal ligament,and longus colli muscle and annular ligaments of trachea at the frequencies of 800-3 000 kHz,3 000 kHz and 3 000 kHz (multiple comparisons),respectively;for comparison of all other paired tissues of prevertebral group there were significant differences at all frequencies (multiple comparisons).Conclusion At certain frequencies,the EI among tissues was significantly different and could discriminate tissues in the anterior approach of the cervical spine.