Carboxyhemoglobin (COHb) values were determined in mice exposed to varying amounts of marijuana and tobacco cigarette smoke utilizing a spectrophotometric technique. Mice were exposed to smoke inhalation in a modified Walton horizontal smoke exposure machine, whereby rodents can be exposed to multiples of 1-min smoke exposure cycles. Smoke exposure was intermittent; during the first 30 sec of each 1-min cycle, the subjects were exposed to smoke diluted either 1:10 or 1:5 with air. During the second half of the cycle the animals were given fresh air. There was a positive linear relationship between COHb values obtained and the number of puffs of marijuana smoke administered via either 2, 4, 6, or 8 "puffs" of marijuana smoke. COHb levels in plasma did not increase in animals given multiple 8-puff episodes of smoke daily as long as a 60-min period was interposed between smoking episodes. COHb values in mice exposed to tobacco smoke were significantly higher than those in mice receiving equal numbers of exposures to marijuana smoke. Mean COHb values of mice receiving 8 consecutive puffs of marijuana smoke were 18.6 and 22.0% saturation, but CO was rapidly cleared from the blood. This rapid clearance suggests that the binding affinity of CO for mouse hemoglobin may be be weaker than that of human hemoglobin. Mice similarly exposed to 6 or 8 puffs of tobacco smoke had mean COHb values of 24.6 and 28.5% saturation, respectively. No acute lethal effects were observed in mice receiving multiple daily episodes of 8 puffs per episode of marijuana smoke, whereas mice exposed to a single 8-puff episode of tobacco smoke suffered about 50% acute lethal effects.
The elimination of intravenously administered Guanazole-14C was studied in female, weanling, Yorkshire white pigs to determine the total percentage of such a dose eliminated in the urine. Ninety-six percent of the dose was eliminated after 72 hours. This elimination percentage was then utilized to determine the amount of Guanazole-14C absorbed after topical application of the drug. After 48 hours, approximately 0.2% of the topically applied dose was absorbed through the skin of the test animals. Most tissue levels were not significant. However, adrenals and ovaries, although small, showed high specific activity levels of radioactivity. Bone samples after 24 hours also showed significant uptake. A significant percentage of the applied dose was generally detected at and around the site of application.
S403 INTRODUCTION: The use of TEE in children has increased with the arrival of smaller TEE probes. The high quality TEE image may prevent the need for invasive cardiac catheterisation to diagnose congenital heart disease. In adults, TEEs' are usually performed with topical analgesia and light sedation, however this method is seldom tolerated by children. Deeper sedation using oral agents also often fails. The aim of this study is to review prospectively the anesthetic technique developed by our anesthesia department for pediatric TEE. METHODS: Patients are assessed pre-procedure and consent obtained. Prior to induction of anesthesia the patient gargles lidocaine mouthwash (1% - 25cc). Monitors are applied and an IV sited with nitrous oxide sedation. The patient receives O2 (2 l/min) by nasal cannula during induction of anesthesia which is with: midazolam (25mcg/kg), fentanyl (1mcg/kg), glycopyrrolate (5mcg/kg) and propofol (0.5-1 mg/kg). Topical lidocaine spray (10%, 1-4 puffs, max. 2mg/kg) is applied to the pharynx. Anesthesia is maintained with propofol by infusion (5-10 mg/kg/hr). The TEE probe is passed as the patient loses consciousness and is protected by a bite block next to which O2 (8 l/min) flows. Jaw thrust is used to maintain the airway as needed. Any patient movement is treated with further propofol (0.25mg/kg). Respiration is spontaneous. Once the TEE has finished the patient is cared for in the PARR unit until recovered. Exclusion criteria include severe respiratory disease, GERD, cardiac lesions not tolerating vasodilation. RESULTS: Ten patients are reported. The mean age was 12.5 +/- 4.8 yrs and weight 35.3 +/- 22.8 kg. Sedation and recovery times are shown in Table 1. All patients remained hemodynamically stable (Table 2). Image quality was good to excellent for all studies. Complications, which were transient and minor are shown in Table 3.Table 1: Time (min) for stages of procedure (mean +/- SD)Table 2: Cardiorespiratory changes (mean +/- SD)Table 3: Complications and dose of propofol (mean +/- SD)CONCLUSIONS: We have described an anesthetic technique which allows a child to undergo a TEE in a comfortable and safe manner with the TEE operator and the anesthesiologist sharing the airway. Propofol allows for an easily controlled level of anesthesia and along with good mucosal anesthesia the probe can be placed without patient distress. The transient desaturations on induction were related to the propofol bolus which must be carefully titrated.
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