A two-stage approach to positioning and identification of tracheal intubation using LED-based lightwand and acoustic models.

This paper proposes a two-stage approach to positioning and identifying tracheal intubations by computer-assisted diagnosis system. First, an innovated LED-based lightwand is developed for positioning the opening of the trachea and inserting the endotracheal tube rapidly. The proposed LED-based lightwand instrument significantly reduces the effects of temperature reaction without changing transillumination through the tissue. After intubation, breath sound analysis instrumentation is developed and assists for identifying the accurate tube position. To overcome the fast and overstepped variations of amplitude, a high sensitivity omni dimensional microphone and an automatic gain control device with linear phase property are calibrated and conducted into experiments of operating intubations. User-friendly interface software is also developed to analyze and transcribe the physiological characteristics of the collected breath sound corpus. Several subjective and objective experiments are performed to examine the practicability of the proposed approach and systems. The preliminary results show that the proposed LED-based lightwand instrument outperformed in the tip temperature without the influence on transillumination. The proposed parameters of average vibration parameter variance (AVPV) and frequency-domain energy variance (FEV) revealed the potential for distinguishing between the tracheal and esophageal intubations.

Use of a topical anesthetic cream (EMLA) to reduce pain after hemorrhoidectomy.

BACKGROUND AND OBJECTIVES: Hemorrhoidectomy usually leads to severe postoperative pain that often causes urinary retention. Topical EMLA cream (lidocaine 2.5% and prilocaine 2.5%) has been used extensively in the clinical setting. This prospective study tested the effectiveness of EMLA cream for postoperative pain control after hemorrhoidectomy. METHODS: Thirty patients admitted for hemorrhoidectomy were enrolled and randomly assigned into either a control group (n = 15) or EMLA group (n = 15). Postoperatively, the control group received approximately 5 g of neomycin ointment, and the EMLA group received approximately 5 g of EMLA. A visual analog scale (VAS) score was recorded on arrival in the postanesthesia recovery unit (PAR), after 2 hours in the PAR, on the first postoperative evening, and on the first postoperative morning. The requested frequency and dosage of meperidine, the first spontaneous voiding time, the frequency of single urinary catheterization, and a patient satisfaction score were also obtained. RESULTS: The VAS score and frequency and dosage of meperidine injections were significantly lower in the EMLA group than in the control group (P < .01). The voiding time was significantly later in the control group (P = .04). The frequency of single catheterization was significantly lower in the EMLA group than in the control group (P = .03). Patient satisfaction with postoperative pain control was significantly higher in the EMLA group than in the control group (P < .01). No systemic complications were observed. CONCLUSIONS: Topical EMLA cream decreased pain intensity and meperidine requests, reduced the frequency of single catheterizations, and improved patient satisfaction with postoperative pain management after hemorrhoidectomy in adults.

Earlier cessation of desflurane supply in closed-circuit anesthesia reduces emergence time in patients undergoing breast surgery.

BACKGROUND: Minimizing the time of anesthesia emergence can facilitate faster patient turnover in the operating rooms of a busy surgery center. According to Lin's new concept of inhalation uptake, after turning off the vaporizer under close-circuit anesthesia (CCA) with a very low fresh gas flow rate, the concentration of desflurane decreases at a slow rate. The aim of this study was to determine if earlier cessation of desflurane supply would shorten the emergence time and at the same time register the changes of desflurane concentration in the circuit after turning off the vaporizer. METHODS: 30 patients were randomly assigned to two groups, i.e., the control group and the study group. In the control group, the desflurane supply was continued up till the end of the operation, while in the study group the desflurane supply was cut off prior to the suturing the skin. In the study group, data regarding the hemodynamic changes, time from turning off desflurane with high flow washout to wakefulness, and the inspired as well as the expired desflurane concentrations at the low-flow anesthetic phase were collected. The time required from high flow washout to emergence was recorded in all patients. Inter-group and intra-group data were analyzed with nonparametric 2-independent-samples Mann-Whitney test and 2 related-samples Wilcoxon signed ranks test, respectively. RESULTS: Under CCA with similar surgical duration, the patients in the study group emerged from anesthesia significantly faster than those in the control group (5.6 +/- 1.9 min versus 8.8 +/- 2.3 min; P < 0.05), without molestation of stable hemodynamic signs. At the low-flow wash-in stage, the inspired desflurane concentrations were significantly higher than the expired ones from 0 to 2nd min; no significant difference was noted from the 3rd to 6th min, but after which the expired concentrations were significantly higher. Desflurane concentrations decreased most noticeably during the first 5 min (0.35 +/- 0.14%), and then the decrease was moderating from 6th to 10th min (0.21 +/- 0.58%) and staggered from 11th to 15th (0.14 +/- 0.06%). The mean duration of low flow wash was 25.6 +/- 11.6 min. No patient reported awareness during surgery. CONCLUSIONS: Ceasing desflurane supply earlier in CCA (250 mL/min) significantly shortens emergence time without significant hemodynamic changes.

Paravertebral transcutaneous electrical nerve stimulation reduces movement during general anesthesia with isoflurane.

We evaluated paravertebral transcutaneous electrical nerve stimulation (TENS) as a means of enhancing anesthesia during hysterectomy. Patients were randomly assigned to experimental (n = 21) and control (n = 20) groups. Anesthesia with isoflurane was performed uniformly for all patients. Paravertebral (T6 and T7) TENS (50 mA, 15 Hz, continuously) was applied in the experimental group. After 15 min of isoflurane, a lower abdominal, skin-to-adipose-tissue incision was made. Seventeen of 21 patients in the experimental group showed no arm or leg movements during the incision, compared to 8 with 20 patients in the control group (P = 0.007). TENS deserves further exploration as an adjunct technique for general anesthesia.

Minimal dosage of tetracaine supplemented with epinephrine for spinal anesthesia in anorectal surgery.

BACKGROUND: Spinal anesthesia has been widely used in clinical setting with relatively high incidences of hypotension and bradycardia. Lowering the dosage of local anesthetics is one of the methods to mitigate the side effects. This study was to evaluate the feasibility of lowering the dosage of tetracaine in spinal anesthesia for patients undergoing anorectal surgery. METHODS: Thirty patients scheduled for anorectal surgery were studied. Patients were randomly divided into experiment (n = 15, 3.0 mg of tetracaine) and control groups (n = 15, 6.0 mg of tetracaine). The extent of analgesia was assessed by loss-of-sensation to pinprick. Dermatomic level of the sensory block was evaluated and recorded every minute for 10 minutes. BP and HR were recorded at 3-min interval for the 10-min in the study period. Numeric data were statistically analyzed with Student's t-test. The categorical data were compared using the chi-square test. P-value less than 0.05 was considered statistically significant. RESULTS: Ten min after the injection, the mean peak level of sensory block reached T12 for experiment and T9 for control groups. A noticeable difference in frequency of hypotension between two groups was found though it was not statistically significant (P = 0.08). Incidences of moderate bradycardia and severe bradycardia were similar in both groups, being 13.3% and 6.7% respectively. CONCLUSIONS: This study confirmed that lowering the dosage of tetracaine to 3.0 mg could equally provide adequate spinal anesthesia for anorectal surgery. The reduced dosage has the tendency of reducing the rate of hypotension, but apparently it does not reduce the incidence of bradycardia.