The difficult cases were mostly aged <1 year. The association between difficult laryngoscopy and the distances between the lower lip border and menthom, ear tragus and corner of the mouth, and ear lobe and corner of the mouth can be summarized in an equation that may have potential use in the prediction of difficult laryngoscopy.

Sir, Cooling tetracaine to reduce pain of instillation before surgeryTetracaine is one of the most common agents that are used for analgesia in the eyes. However, instillation of tetracaine is accompanied by ocular pain and a burning sensation. 1,2 It has been suggested that warming the local anesthetic agent before injection may reduce the injection pain of these drugs; 1 however, there is controversy in this regard. 2 Our study aimed at evaluating the effect of cold tetracaine drop on post-instillation ocular pain and burning sensation in patients undergoing phacoemulsification.This randomized controlled trial was carried out on 60 patients aged 50-70 years who underwent phacoemulsification at Farabi hospital during 2006. Exclusion criteria were an earlier history of ophthalmic surgery and addiction to opioids. Patients were randomly allocated into two groups of cold (case) and warm (control) tetracaine eye drops. In the case group, the tetracaine drop was preserved in the refrigerator (4 1C) whereas in another group, the drops were at room temperature (25 1C). The volunteers received two drops of tetracaine before surgery at a 5 min interval. Immediately after administration of the first drop, a physician, who was blinded to the temperature of the administered drop, evaluated the patients with regard to the burning sensation using a visual analogue scale (VAS). For this purpose, a ruler scaled 0 (no pain) to 10 (the most severe pain that has ever been experienced) was used, and the patients were asked to show the severity of their pain on the ruler. Then, as premedication, 0.5-1 mg midazolam was administered to all patients and phacoemulsification was carried out.Baseline characteristics of the patients have been shown in Table 1. The mean burning score, as measured by VAS, was significantly lower in the case group than in the control group immediately after instillation of drops (Table 1, Figure 1). CommentsIn earlier studies, it has been shown that cooling the site of the local anesthetic injection results in a reduction in post-injection pain. 3,4 Similar to our study, Li et al.,5 showed that cooling the tetracaine eye drop results in reducing the ocular burning sensation during instillation. Although most of his cases reported less pain with cold tetracaine, 9% noted significantly more discomfort with cold tetracaine. But they enrolled only healthy volunteers, and their findings might not be generalizable to the patient population.Our results showed that cooling tetracaine reduces the pain on instillation of topical anesthesia in patients undergoing phacoemulsification.

Background:During anesthesia, continuous body temperature monitoring is essential, especially in children. Anesthesia can increase the risk of loss of body temperature by three to four times. Hypothermia in children results in increased morbidity and mortality. Since the measurement points of the core body temperature are not easily accessible, near core sites, like rectum, are used.Objectives:The purpose of this study was to measure skin temperature over the carotid artery and compare it with the rectum temperature, in order to propose a model for accurate estimation of near core body temperature.Patients and Methods:Totally, 124 patients within the age range of 2 - 6 years, undergoing elective surgery, were selected. Temperature of rectum and skin over the carotid artery was measured. Then, the patients were randomly divided into two groups (each including 62 subjects), namely modeling (MG) and validation groups (VG). First, in the modeling group, the average temperature of the rectum and skin over the carotid artery were measured separately. The appropriate model was determined, according to the significance of the model’s coefficients. The obtained model was used to predict the rectum temperature in the second group (VG group). Correlation of the predicted values with the real values (the measured rectum temperature) in the second group was investigated. Also, the difference in the average values of these two groups was examined in terms of significance.Results:In the modeling group, the average rectum and carotid temperatures were 36.47 ± 0.54°C and 35.45 ± 0.62°C, respectively. The final model was obtained, as follows: Carotid temperature × 0.561 + 16.583 = Rectum temperature. The predicted value was calculated based on the regression model and then compared with the measured rectum value, which showed no significant difference (P = 0.361).Conclusions:The present study was the first research, in which rectum temperature was compared with that of skin over carotid artery, to find a safe location with easier access and higher accuracy for estimating near core body temperature. Results obtained in this study showed that, using a model, it is possible to evaluate near core body temperature in children, by measuring skin temperature over carotid artery.

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