The Study Of Pressure And Force Distribution On Pharyngeal Tissues Of Manikin Caused By Two Kinds Of Laryngoscopes Used By Doctors Of Different Seniority

Objective:To compare pressure and force distribution on pharyngeal tissues in tracheal intubations using Macintosh Direct Laryngoscope and McGrath visual laryngoscope by doctors of different seniority.Quantitative measurement of the pressure caused by two kinds of laryngoscopes was conducted to provide a reference for clinical work and research.Methods:A total of 40 doctors,20 anesthesiologists with more than five years of clinical experience comprised senior doctors group(groupA);20 residents with one year working experience of clinical standardized training comprised junior doctors group(group B).Both two groups conducted median racheal intubations on the same manikin(type HX-50),using direct laryngoscopes and cisual laryngoscopes at random orders.Computer monitoring software was used to record results of the experiment.The laryngoscopic exposure was graded by Cormack grade,ranging from Ⅰto Ⅱclass.Multi-points MFF pressure test system was calibrated,Curve Expert software was applicated for a function fitting and then coefficients and constants were inputted into data acquisition system TracerDAQ Professional,thin-film pressure sensors were designed as three-point type sensors and respectively fixed on the former 1 / 3 concave surface of laryngoscopic lens of the Macintosh Direct Laryngoscope and McGrath glidescope.Software sampling frequency was 10Hz(8 data per second collection),the system would automatically record the intubation time and surface pressure of laryngoscopic lens after a complete exposion and calculate the laryngoscopic lens surface pressure(pressure* duration time,N.S),mean pressure(N),peak force(N).Statistics of the experimental data were analyzed by SPSS 19.0 software,count data was showed as mean± and standard deviation(X±S),comparison between group was conducted by single factor analysis of variance in bundle data,P < 0.05 as the standard for differences with statistical significance.Results:When senior physicians used direct laryngoscopy for tracheal intubation,the impact force was(39.18 + 1.4),mean pressure was(0.78 + 0.7)and the peak force was(5.73 +1.6),all significantly lower than those in junior physician group,impact force(6.61 +2.3),mean pressure(1.66 + 1.2)and the peak force(10.70 + 2.9),the differences were statistically significant(P < 0.05).While using glidescope for tracheal intubation,impact force,average pressure and peak stress of A and B showed no significant difference(p>0.05).Three-point sensors record of pressure distribution of two different laryngoscopes was more similar,about 50% of the laryngoscope one-sided impact force was concentrated in the remote sensor of laryngoscopic lens,about 20%-30% of the impact force distributed in the intermediate sensor and proximal sensor.Conclusion:Tissue pressure caused by tracheal intubation under direct laryngoscopy among senior doctors was significantly lower than that among junior doctors.While the pressure on pharyngeal tissues during intubations of both two groups was similar.Force distributions of tracheal intubation under direct laryngoscopes and visual laryngoscopes were in line with each other,indicating the main distribution area of the pressure was at the distal end of the laryngoscopic lens.