Yesim Ates

The mechanical properties of intact and traumatized epidural catheters.

Comparative data on the mechanical properties of epidural catheters used clinically are not available. We performed a controlled laboratory investigation to assess the mechanical performance of three different intact or traumatized catheter types (Polyurethane, clear nylon, and radiopaque nylon catheters, designed for 18-gauge Tuohy needles). We studied a control (intact) and two trauma groups (needle bevel and surgical blade). Catheters were loaded to their breaking points by using a Lloyd LS500 material testing machine (Lloyd, Southampton, UK). Maximal load and extension values before breakage were measured, and modulus of elasticity and toughness values were calculated. Intact polyurethane catheters did not break within the limits of the experimental study (extension up to 3 times the original length of a specimen). The toughness values obtained from polyurethane and clear nylon catheters were significantly higher than those for the radi- opaque catheters in intact specimens (P < 0.05). In the traumatized groups, polyurethane catheters had the highest toughness values (P < 0.05). Modulus of elasticity values were higher in both control and trauma groups of the radiopaque catheters when compared with the polyurethane and clear nylon catheters, which indicates a higher stiffness to elastic deformation (P < 0.05). In conclusion, polyurethane catheters are the most durable catheter type to tensile loading, either intact or traumatized. Mechanical properties can be used to predict complications related to the clinical use of these catheters. Implications Using a computer-assisted material testing machine, we studied the mechanical properties of three different types of epidural catheters, either intact or traumatized, in a blinded, controlled study. This information may be vital to clinicians who implant epidural catheters by helping them choose a catheter that has the lowest probability of failure.

Should we reevaluate the variables for predicting the difficult airway in anesthesiology

Anesthesiologists have often been confronted with the difficult question of determining which patient will present an increased difficulty for endotracheal intubation. The limits of the previously reported morphometric airway measurements for predicting difficult intubation have inadequately addressed the normal patient population variables. We designed this prospective study to investigate the age and sex-related changes in the morphometric measurements of the airway in a large group of patients without anatomic abnormality and a group of cadavers. Hyomental, thyromental, sternomental distances, neck extension, and Mallampati scores were evaluated in 12 cadavers and in 334 patients. Patients were allocated to three groups based on age: Group 1 (20–30 yr), Group 2 (31–49 yr), and Group 3 (50–70 yr). Male and female sex differences were also evaluated. Hyomental distance was the only variable not affected by age. In addition, the mean population values were less than the threshold values suggested as criteria for difficult endotracheal intubation. All the other criteria were age-dependent and inversely affected by the increase in age. Male sex was also a distinction for increased measurements of all the morphometric distances. The mean degree of neck extension was similar in both sex groups. This study provides a more comprehensible approach to the morphometric measurements of the human airway. Adequate data of normal values may help the clinician to identify patients that are outside the range and therefore may be challenging.

Ultrasound-guided obturator nerve block: a sonoanatomic study of a new methodologic approach.

BACKGROUND: Obturator nerve block is one of the most technically challenging regional anesthesia techniques. Recently, the characteristics of the nerve have been described using ultrasound. However, clinical application of proximal ultrasound-guided obturator nerve block on patients has not been reported. In this study, we used ultrasound to describe the anatomical localization of the obturator nerve and its two branches in cadavers, volunteers, and also patients. METHODS: A hyperechoic triangular shape formed by the superior pubic ramus, posterior margin of the pectineus muscle and anterior aspect of the external obturator muscle containing the obturator vessels and nerve was defined by ultrasound imaging in cadavers. In eight volunteers, bilateral obturator nerve images were obtained and the distances to specific landmarks (femoral artery, femoral vein, and pubic tubercle) were recorded. Ultrasound-guided obturator nerve block was further performed in 15 patients by using the previously defined approach. The final distance of the needle tip to the femoral artery, distances between the needle insertion point to the pubic tubercle and the depth of needle insertion were recorded. RESULTS: The rates of common obturator nerve, anterior and branching obturator nerve pattern visibility with ultrasound were determined in 12/16, 13/16, and 7/16 sites in volunteers, respectively. Mean (sd) values of critical landmarks obtained from volunteers were obturator nerve-femoral vein 12.9 ± 2.9 mm and obturator nerve-pubic tubercle 19.9 ± 2.6 mm. Mean measurements obtained from patients were: femoral artery- needle tip 18.5 ± 2.4 mm, needle depth 48.3 ± 10.4 mm, pubic tubercle- needle insertion point (horizontal) 18.8 ± 2.0 mm, and pubic tubercle- needle insertion point (vertical) 21.1 ± 2.9 mm. Visual analog scale scores obtained from patients at 1 and 24 h were lower compared to baseline values (P < 0.001). Ninety-three percent (14 of 15) of the patients reported satisfaction from the block. CONCLUSIONS: Landmarks defined in this clinical trial can be used in patients for obturator nerve block with ultrasound guidance.

Comparison of prilocaine and bupivacaine for post-arthroscopy analgesia: A placebo-controlled double-blind trial

Arthroscopic surgery requires early postoperative analgesia for early discharge and early rehabilitation of patients. To accomplish the effectiveness of intraarticular application of local anesthetics, a placebo-controlled double-blind trial was performed. Results were evaluated using the visual analog scale on a blind basis. The mean pain scores were generally lower in the bupivacaine group than in the control or prilocaine group. There were no statistically significant differences between the oral intake of analgesics and the level of analgesia obtained in all three groups. We consider the local application of analgesics to be ineffective for post-arthroscopy analgesia.

Postoperative analgesia in children using preemptive retrobulbar block and local anesthetic infiltration in strabismus surgery

Background and Objectives. Postoperative pain management in pediatric strabismus patients is infrequently studied. Pediatric patients can be mobilized earlier if postoperative pain is minimized. In this study, two different regional anesthetic techniques, retrobulbar block and local infiltration, were compared with a “no block” control group for the postoperative management of pain in pediatric patients undergoing elective strabismus surgery. Methods. Thirty patients were randomly allocated to one of the study groups: group 1 (n = 10) control, group 2 (n = 10) retrobulbar block, and group 3 (n = 10) subconjunctival bupivacaine infiltration. The parameters that were evaluated during the early postoperative period (6 hours) were circulatory, pain scores by Visual Analog Scale (VAS) and Modified Pediatric Objective Pain Scale (MPOPS), additional analgesic requirement, nausea, and vomiting. The parameters that were evaluated after discharge from the hospital (on postoperative days 1 and 2) through questionnaires were additional analgesic requirement, nausea, vomiting, sleep disturbances, activity, and appetite. Results. Group 3 had significantly higher VAS and MPOPS scores at postoperative 120, 180, 240, 300, and 360 minutes than groups 1 and 2 (P < .05). Patients in group 2 seemed to have a higher incidence of nausea and vomiting both in the early (6 hours) and late postoperative (postoperative days 1 and 2) periods; however, the difference was not statistically significant. Group 2 required less analgesic compared with groups 1 and 3 during the late postoperative period. Late postoperative activity and appetite were better in groups 2 and 3. Conclusions. Because there was no significant difference in terms of postoperative analgesia in the retrobulbar block or subconjunctival local anesthetic infiltration groups compared with the control group, we suggest that conventional methods of pain treatment are adequate for postoperative analgesia in strabismus surgery.

Evaluation of the longus colli muscle in relation to stellate ganglion block.

Background and Objectives: The longus colli (LC) muscle is an important structure of the anterior cervical spine and has a critical role in stellate ganglion block. This technique involves withdrawing the needle to locate its port for injection above the anterior surface of the LC muscle; however, its exact thickness at the C5, C6, and C7 levels has not been measured. The aim of this anatomic and magnetic resonance-supported study was to evaluate the thickness of the LC muscle at these levels from the anterior tubercle of each vertebra toward the vertebral body at 5-, 10-, and 15-mm distances to provide precise anatomic data for stellate ganglion block. Methods: Ten cadavers, 60 vertebral body specimens, and cervical magnetic resonance imaging (MRI) scans of 40 adult patients were used for measurements. Results: The main findings of this study are that the thickness of the LC muscle varies between 5.0 and 10.0 mm at C6 and C7 in cadavers and between 8.0 and 10.0 mm in MRI scans. Sex has an important role; MRI scans revealed that male patients have a considerably thicker LC muscle at each vertebral level. Conclusion: We found a highly variable thickness of the LC muscle in anatomic and imaging studies, which may lead to negative block results.

The impact of two arterial catheters, different in diameter and length, on postcannulation radial artery diameter, blood flow, and occlusion in atherosclerotic patients.

PurposeArterial cannulation is a common intervention in anesthesia practice. However, the success rates and complications of radial arterial cannulation with 20-G or smaller catheters in patients with atherosclerosis have been underevaluated. The aim of this prospective randomized study was to compare the efficacy of and complications with 20- and 22-G catheters for radial arterial cannulation in atherosclerotic patients.MethodsThirty patients with atherosclerosis, American Society of Anesthesiologists (ASA) III–IV, undergoing general anesthesia were enrolled in the study. Radial artery cannulation was performed in group 20G (n = 15) with a 20-gauge (20 × 1.1 × 33 mm; flow, 61 ml·min−1) catheter and in group 22G (n = 15) with a 22-gauge (22 × 0.9 × 25 mm; flow, 36 ml·min−1) catheter. Radial artery systolic blood flow (SBF) and radial artery diameter (RAD) were assessed by a Doppler ultrasound probe before cannulation and 24 h after decannulation for vascular complications. The number of puncture attempts, arterial blood gas samples, and manual flushes; total heparinized solution consumption; duration of cannulation; decannulated radial arterial systolic blood flow; postcannulation RAD; and vascular complications such as occlusion, hematoma, pseudoaneurysm, bleeding, and thrombosis were noted. The Mann Whitney U-test, χ2 test, and one-sample t-test were used. Values are expressed as medians and quartiles and P < 0.05 was considered as significant.ResultsThe number of puncture attempts was greater in group 20G (range, 1 to 4) than in group 22G (range, 1 to 2; P = 0.02). In group 20G patients, postoperative RAD was larger than preoperative RAD (P = 0.02) and postoperative SBF was lower than preoperative SBF (P = 0.03). In group 22G patients postoperative SBF was higher than preoperative SBF (P = 0.03), while there was no significant difference between preoperative and postoperative RAD. The occlusion rate of atherosclerotic radial arteries was 6% with the 22-gauge catheter and 26% with the 20-gauge catheter (P = 0.02).ConclusionA 22-gauge catheter for radial arterial cannulation in patients with atherosclerosis provides unchanged postcannulated radial artery diameter, decreases postcannulation complications, and improves the first-attempt success rate.