Effect of activation and preactivation on the mechanical behavior and neutral position of stainless steel and beta-titanium T-loops / 대한치과교정학회지

OBJECTIVE: To quantify, for each activation, the effect of preactivations of differing distribution and intensity on the neutral position of T-loops (7-mm height), specifically the horizontal force, moment to force (M/F) ratio, and load to deflection ratio. METHODS: A total 100 loops measuring 0.017 x 0.025 inches in cross-section were divided into two groups (n = 50 each) according to composition, either stainless steel or beta-titanium. The two groups were further divided into five subgroups, 10 loops each, corresponding to the five preactivations tested: preactivations with occlusal distribution (0degrees, 20degrees, and 40degrees), gingival distribution (20degrees), and occlusal-gingival distribution (40degrees). The loops were subjected to a total activation of 6-mm with 0.5-mm iterations. Statistical analysis was performed using comprised ANOVA and Bonferoni multiple comparison tests, with a significance level of 5%. RESULTS: The location and intensity of preactivation influenced the force intensity. For the M/F ratio, the highest value achieved without preactivation was lower than the height of the loop. Without preactivation, the M/F ratio increased with activation, while the opposite effect was observed with preactivation. The increase in the M/F ratio was greater when the preactivation distribution was partially or fully gingival. CONCLUSIONS: Depending on the preactivation distribution, displacement of uprights is higher or lower than the activation, which is a factor to consider in clinical practice.

Useful Method for Neutral Positioning of the Femoral Stem in Cementless Total Hip Arthroplasty / 대한고관절학회지

PURPOSE: The aim of this study was to evaluate the usefulness of a method for positioning the femoral stem in neutral position refer to the measured value of "lateral distance" in pre-operative templating and the femoral stem position post-operatively. MATERIALS AND METHODS: A total of 81 hips in 76 patients underwent cementless total hip arthroplasty between March 2008 and April 2012 using the C2 stem (Lima Corporate S.P.A, Udine, Italy). We measured the perpendicular distance from the lateral outermost part of the greater trochanter to the lateral outermost part of the femoral stem (lateral distance, LD) in pre-operative templating. We aimed to insert the femoral stem in neutral position by comparing LD measured intra-operatively. We evaluated the position of the femoral stem on post-operative plain radiography. We compared the result of post-operative re-measurement of the LD with that of pre-operative measurement. RESULTS: In all of the 81 cases, the femoral stem was inserted in neutral position, defined as the femoral stem position within 3degreesvalgus or varus. The average angle of the inserted femoral stem was 1.20degrees(0.003-2.85degrees). LD measured in preoperative templating was 15.6 mm(10-21.5 mm), and it showed no correlation ratio with LD; LD re-measured post-operatively was 15.9 mm(10.3-23.5 mm) (P=0.781). CONCLUSION: Measuring LD pre-operatively and using the value intra-operatively is an effective method for insertion of the femoral stem in neutral position.

Comparison of the ease of laryngeal mask airway ProSeal insertion and the fiberoptic scoring according to the head position and the presence of a difficult airway / 대한마취과학회지

BACKGROUND: The sniffing position is recommended for conventional laryngeal mask airway (LMA) insertion. However, there has been a high success rate of LMA insertion with the head in the neutral position. The effect of a difficult airway on the ease of LMA insertion is not clear. In this study, we compared the ease of LMA ProSeal(TM) (PLMA) insertion and the fiberoptic scoring according to the head position and the presence of a difficult airway. METHODS: After obtaining informed consent from the subjects, we enrolled 144 adult patients (age range: 18-65) with an ASA physical status 1 or 2. After evaluation of the airway, all the patients were grouped into the EA (easy airway) group (n = 68) and the DA (difficult airway) group (n = 76). According to the head position, each group was divided into the EA-SE (extension) group (n = 35), the EA-SN (sniffing) group (n = 33), the DA-SE group (n = 39) and the DA-SN group (n = 37). The success rate and insertion time at the first attempt were evaluated. The position of the PLMA was fiberoptically scored from the mask aperture of the airway tube in the original head position. After the head position was changed to the sniffing and neutral positions in the SE and SN group, respectively, the position of PLMA was re-evaluated fiberoptically. RESULTS: The success rate and insertion time at the first attempt and the fiberoptic score showed no significant difference among the groups. After head position was changed, there were no significant changes in the fiberopitc scores. CONCLUSIONS: A difficult airway and the head position had no influence on the ease of PLMA insertion and the fiberopic score. Therefore, the head position can be selected according to the individual patient's situation.

Randomized Study Comparing the Sniffing Position with the Neutral Position for Lightwand Intubation / 대한마취과학회지

BACKGROUND: The sniffing position is recommended for optimal glottic visualization under direct laryngoscopy. However, there is no study assessing whether sniffing position is superior to a neutral position during lightwand-guided intubation. This prospective, randomized study was performed to compare facilitation of lightwand-guided intubation between the sniffing and neutral positions. METHODS: The study included 180 patients with normal cervical spines requiring tracheal intubation for elective surgery. Patients were randomly allocated into two groups: neutral or sniffing position. Mallampati class, mouth opening distance, thyromental distance, and laryngeal view grade were measured. A lightwand railroaded with an endotracheal tube was bent 90degrees at 5 cm from the distal end for both groups. Time to intubation, success rate and intubation time for the first attempt, hydrodynamic changes, and BIS values were recorded. RESULTS: There were no significant differences in time to intubation, success rate and intubation time of the first trial, hydrodynamic changes, or BIS values between the two positions. CONCLUSIONS: Routine use of the sniffing position does not provide any advantage over the neutral position during lightwand-guided intubation.

The Comparison of Suceess Rates of Lightwand Facilitated Tracheal Intubation in Different Head Positions (Neutral Position versus Sniffing Position) / 대한마취과학회지

BACKGROUND: It has been known that a patient head in sniffing position for lightwand facilitated tracheal intubation is not an anatomically appropriate method. However, there is no evidence nor study whether it is true or not. In this study, we compared success rates of lightwand facilitated tracheal intubation in neutral position versus sniffing position. METHODS: With informed consent, sixty adult patients of ASA physical status I or II were randomly allocated into two groups: neutral position (N) or sniffing position (S) group. A lightwand and tube were bent at approximately a 90degrees degree angle for N group and a 60 degree angle for S group on the basis of mouth axis and pharyngeal axis. The time to intubation, success rates of 1st trial of intubation, overall intubation success rates, hemodynamic changes and complications during the procedure were recorded. RESULTS: There was no significant difference in the time to intubation, success rates of 1st trial of intubation, overall intubation success rates, hemodynamic changes and complications between neutral position and sniffing position groups. CONCLUSIONS: Success rates of lightwand facilitated tracheal intubation in neutral position versus sniffing position showed no significant difference. Therefore, both positions are suitable for lightwand assisted intubation.

The Comparison of Suceess Rates of Lightwand Facilitated Tracheal Intubation in Different Head Positions (Neutral Position versus Sniffing Position) / 대한마취과학회지

BACKGROUND: It has been known that a patient head in sniffing position for lightwand facilitated tracheal intubation is not an anatomically appropriate method. However, there is no evidence nor study whether it is true or not. In this study, we compared success rates of lightwand facilitated tracheal intubation in neutral position versus sniffing position. METHODS: With informed consent, sixty adult patients of ASA physical status I or II were randomly allocated into two groups: neutral position (N) or sniffing position (S) group. A lightwand and tube were bent at approximately a 90degrees degree angle for N group and a 60 degree angle for S group on the basis of mouth axis and pharyngeal axis. The time to intubation, success rates of 1st trial of intubation, overall intubation success rates, hemodynamic changes and complications during the procedure were recorded. RESULTS: There was no significant difference in the time to intubation, success rates of 1st trial of intubation, overall intubation success rates, hemodynamic changes and complications between neutral position and sniffing position groups. CONCLUSIONS: Success rates of lightwand facilitated tracheal intubation in neutral position versus sniffing position showed no significant difference. Therefore, both positions are suitable for lightwand assisted intubation.