Anesthesia and analgesia
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Anesthesia and analgesia · Jun 2000
Toast and tea before elective surgery? A national survey on current practice.
A more tolerant approach to preoperative fasting guidelines for healthy adults undergoing elective surgery was recently recommended by a task force appointed by the American Society of Anesthesiologists. This recommendation liberalizes the intake of clear liquids and specifically allows a light breakfast (e.g., toast and tea or coffee) up to 6 h before elective surgery. We conducted a national survey to determine whether anesthesiologists giving anesthesia in an outpatient setting in the United States were currently following these recommendations, and whether institutional policy reflects these new guidelines. The population consisted of the entire active membership of the Society for Ambulatory Anesthesia, providing an initial sample size of 623 subjects. Most conservatively calculated, we had a response rate of 59.6%. A total of 62% of the respondents said they have an institutional policy in place to allow clear liquids orally 2-3 h before the induction of anesthesia. However, only 35% of the respondents said their institutions had a policy in place allowing a light breakfast 6 h before elective surgery. Nevertheless, only 3% of the responders said they would cancel the operation if a patient actually arrived at the facility after consuming a light breakfast, such as toast and tea 6 h before elective surgery, 32% would delay surgery to later that day, and 65% would proceed without delay. We concluded that most anesthesiologists practicing outpatient anesthesia in the United States have already changed their practice pattern to conform to the recent recommendations of the American Society of Anesthesiologists task force on preoperative fasting time. ⋯ Findings of this national survey conducted among active members of the Society for Ambulatory Anesthesia may encourage anesthesiologists throughout the world to take a more liberal attitude toward allowing clear liquids 2-3 h and a light breakfast 6 h before an elective surgery in healthy patients.
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Anesthesia and analgesia · Jun 2000
Propofol inhibits Ca(2+) transients but not contraction in intact beating guinea pig hearts.
We investigated whether propofol inhibits Ca(2+) transients and left ventricular pressure (LVP) in intact beating guinea pig hearts at clinical concentrations and whether an inhibition of Ca(2+) transients by propofol results from an impairment of sarcolemmal or of sarcoplasmic reticulum (SR) function. By using a Langendorff's preparation, transmural left ventricular phasic intracellular Ca(2+) concentration ([Ca(2+)](i)) was measured by the fluorescence ratio of indo-1 emission at 385 nm and 456 nm and was calibrated to Ca(2+) transients (in nM). The Ca(2+) transients during each contraction were defined as available [Ca(2+)](i). Sixty hearts were perfused with modified Krebs-Ringer's solution containing lipid vehicle and propofol (1 and 10 microM) in the absence and presence of ryanodine, thapsigargin, and nifedipine, while developed LVP and available [Ca(2+)](i) were recorded. Propofol (10 microM) decreased available [Ca(2+)](i) by 11.0% +/- 1.3% without decreasing developed LVP (% of control, P < 0.05). Propofol (10 microM) caused a leftward shift in the curve of developed LVP as a function of available [Ca(2+)](i). Propofol (10 microM) with nifedipine (1 microM), but not with ryanodine (1 microM) or thapsigargin (1 microM), decreased available [Ca(2+)](i) by 15.5% +/- 1.7% (P < 0.05). Propofol decreases available [Ca(2+)](i) without decreasing cardiac contraction, and it enhances myofilament Ca(2+) sensitivity in intact beating hearts at clinical concentrations. The inhibition of available [Ca(2+)](i) by propofol may be mainly mediated by an impairment of sarcoplasmic reticulum Ca(2+) handling rather than the sarcolemmal L-type Ca(2+) current. ⋯ This is the first study of the effects of propofol on intracellular Ca(2+) concentration and myofilament Ca(2+) sensitivity under physiologic conditions in intact isolated beating guinea pig hearts.