Anesthesia and analgesia
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Anesthesia and analgesia · Sep 2002
Randomized Controlled Trial Comparative Study Clinical TrialA comparison of the laryngeal mask airway ProSeal and the laryngeal tube airway in paralyzed anesthetized adult patients undergoing pressure-controlled ventilation.
We compared the laryngeal mask airway ProSeal (PLMA) and the laryngeal tube airway (LTA), two new extraglottic airway devices, with respect to: 1) insertion success rates and times, 2) efficacy of seal, 3) ventilatory variables during pressure-controlled ventilation, 4) tidal volume in different head/neck positions, and 5) airway interventional requirements. One-hundred-twenty paralyzed anesthetized ASA physical status I and II adult patients were randomly allocated to the PLMA or LTA for airway management. A standardized anesthesia protocol was followed by two anesthesiologists experienced with both devices. The criteria for an effective airway included a minimal expired tidal volume of 6 mL/kg during pressure-controlled ventilation at 17 cm H(2)O with no oropharyngeal leak or gastric insufflation. First attempt success rates at achieving an effective airway were similar (PLMA: 85%; LTA: 87%), but after 3 attempts, success was more frequent for the PLMA (100% versus 92%, P = 0.02). Effective airway time was similar. Oropharyngeal leak pressure was larger for PLMA at 50% maximal recommended cuff volume (29 +/- 7 versus 21 +/- 6 cm H(2)O, P < 0.0001), but was similar at the maximal recommended cuff volume (33 +/- 7 versus 31 +/- 8 cm H(2)O). Tidal volumes (614 +/- 173 versus 456 +/- 207 mL, P < 0.0001) were larger and ETCO(2) (33 +/- 9 versus 40 +/- 11 mm Hg, P = 0.0001) lower for the PLMA. The number of airway interventions was significantly less frequent for the PLMA. Airway obstruction was more common with the LTA. When comparing mean tidal volumes in different head/neck positions, the quality of airway was unchanged in 56 of 60 patients (93%) with the PLMA and 42 of 55 (76%) with the LTA (P = 0.01). The PLMA offers advantages over the LTA in most technical aspects of airway management in paralyzed patients undergoing pressure-controlled ventilation. ⋯ The laryngeal mask airway ProSeal offers advantages over the laryngeal tube airway in most technical aspects of airway management in paralyzed patients undergoing pressure-controlled ventilation.
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Anesthesia and analgesia · Sep 2002
Randomized Controlled Trial Clinical TrialThe effect of clonidine on the minimum local analgesic concentration of epidural ropivacaine during labor.
On the basis of the determination of minimum local analgesic concentration (MLAC), ropivacaine has been demonstrated to be less potent than bupivacaine during the first stage of labor. In this study we assessed the effect of clonidine on the MLAC of ropivacaine. Seventy-seven parturients of mixed parity requesting epidural analgesia for labor (cervical dilation, 3-7 cm) were included in the study. They received an epidural bolus of either ropivacaine (n = 30), ropivacaine plus clonidine 30 microg (n = 28), or ropivacaine plus clonidine 60 microg (n = 19) in the second part of the study. The concentration of the ropivacaine solution was determined by the response of the previous parturient in that group by using an up-down sequential allocation. A visual analog pain score of < or =10 mm within 30 min after the epidural bolus (20 mL) was considered an effective response. An effective result directed a 0.01% wt/vol decrement for the next patient. An ineffective result directed a 0.01% wt/vol increment. The MLAC of ropivacaine was 0.097% wt/vol (95% confidence interval, 0.085%-0.108%). It was unaffected by a 30-microg dose of epidural clonidine (0.081% [0.045%-0.117%]) but was significantly decreased by a 60-microg clonidine dose (0.035% [0.024%-0.046%]) (P < 0.001). This study documents a decrease in the MLAC of ropivacaine by clonidine, significant for a 60- microg dose. ⋯ Epidural ropivacaine potency in labor can be increased by the addition of epidural clonidine. This study demonstrates that 60 microg of epidural clonidine significantly decreases the minimum local analgesic concentration of ropivacaine during the first stage of labor but is associated with sedation.
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Anesthesia and analgesia · Sep 2002
Randomized Controlled Trial Clinical TrialThe influence of parecoxib, a parenteral cyclooxygenase-2 specific inhibitor, on the pharmacokinetics and clinical effects of midazolam.
Parecoxib, a parenteral cyclooxygenase-2 inhibitor, is undergoing clinical development as an analgesic/antiinflammatory drug for perioperative use. Parecoxib, an inactive prodrug, is hydrolyzed in vivo to valdecoxib, a substrate for hepatic cytochrome P450 (CYP) 3A4. Thus, potential exists for interactions with other CYP3A4 substrates. In this investigation, we determined the influence of parecoxib on the pharmacokinetics and clinical effects of midazolam, a CYP3A4 substrate, in volunteers. This was a randomized, balanced crossover, placebo-controlled, double-blinded clinical investigation. Twelve healthy subjects aged 23-41 yr were studied after providing IRB-approved informed consent. Midazolam 0.07 mg/kg IV infusion was administered 1 h after placebo (control) or parecoxib 40 mg IV. Venous midazolam concentrations were determined by using liquid chromatography-mass spectrometry/mass spectrometry assay. Pharmacokinetic variables were determined by noncompartmental analysis. Pharmacodynamic measurements included clinical end-points, cognitive function (memory; digit symbol substitution tests), subjective self-assessment of recovery (visual analog scales), and bispectral index. Midazolam plasma concentrations were similar between placebo and parecoxib-treated subjects. No differences were found in midazolam pharmacokinetics (maximal observed plasma concentration, clearance, elimination half-life, volume of distribution) or pharmacodynamics (clinical end-points, digit symbol substitution tests, memory, visual analog scales, bispectral index). Single-bolus parecoxib does not alter the pharmacokinetics or pharmacodynamics of midazolam infusion. Parecoxib did not affect CYP3A4 activity as assessed using midazolam clearance as the in vivo probe. ⋯ Parecoxib, a parenteral cyclooxygenase-2 inhibitor intended for perioperative use as an analgesic/antiinflammatory drug, is a substrate for hepatic cytochrome P450 3A4. The potential for a drug interaction with midazolam, an in vivo CYP3A4 probe, was tested in healthy volunteers. Single-bolus parecoxib does not alter the pharmacokinetics or pharmacodynamics of midazolam.
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Anesthesia and analgesia · Sep 2002
Randomized Controlled Trial Clinical TrialThe use of magnesium sulfate to prevent pain on injection of propofol.
Magnesium sulfate, 2.48 mmol, injected 20 s before the administration of propofol significantly reduced the incidence of pain caused by a propofol injection and may be useful in minimizing this common side effect.