Anesthesia and analgesia
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Anesthesia and analgesia · May 2004
Randomized Controlled Trial Clinical TrialSedation with midazolam leads to reduced pain after dental surgery.
Our principal objective in this study was to evaluate the potential pain reducing effect of i.v. midazolam in patients undergoing oral surgery. One-hundred-twenty-five patients with impacted mandibular third molars requiring removal under local anesthetic were randomized into 2 groups. The first group (n = 64) was administered i.v. midazolam by titration until a clinical end-point of conscious sedation followed by local anesthetic before surgery; the second group (n = 61) was the control and was administered only local anesthetic before surgery. The surgery was performed in a standardized manner in both groups by the same surgeon. Outcome measures were four primary end-points: pain intensity as assessed by a 100-mm visual analogue scale and a 4-point categorized scale hourly for 8 h, time to first analgesic, total analgesic (ibuprofen) consumption over the first 48 h, and a 5-point categorical patient global assessment scale (0 = poor, 1 = fair, 2 = good, 3 = very good, and 4 = excellent). Throughout the 8-h investigation period, patients in the midazolam group reported significantly lower pain intensity scores than those in the control group (19.0 +/- 13.2 mm versus 28.1 +/- 12.8 mm, P < 0.05). The patients in the midazolam group also reported significantly longer time to first analgesic (165.5 +/- 56.5 min versus 202.2 +/- 79.0 min, P < 0.05), less analgesic consumption (1275 +/- 364 mg versus 1688 +/- 407 mg, P < 0.001) and better patient global assessment (3.34 +/- 0.8 versus 2.4 +/- 0.9, P < 0.001). We conclude that systemically administered midazolam is effective in reducing postoperative pain after third molar surgery. ⋯ In this observer blinded study, we found that i.v. midazolam treatment (0.09 mg/kg) has a pain-reducing effect after third molar surgery, thus improving postoperative pain management.
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Anesthesia and analgesia · May 2004
Clinical TrialDantrolene reduces the threshold and gain for shivering.
Dantrolene is used for treatment of life-threatening hyperthermia, yet its thermoregulatory effects are unknown. We tested the hypothesis that dantrolene reduces the threshold (triggering core temperature) and gain (incremental increase) of shivering. Healthy volunteers were evaluated on 2 random days: control and dantrolene (approximately 2.5 mg/kg plus a continuous infusion). In Study 1, 9 men were warmed until sweating was provoked and then cooled until arteriovenous shunt constriction and shivering occurred. Sweating was quantified on the chest using a ventilated capsule. Absolute right middle fingertip blood flow was quantified using venous-occlusion volume plethysmography. A sustained increase in oxygen consumption identified the shivering threshold. In Study 2, 9 men were given cold lactated Ringer's solution i.v. to reduce core temperature approximately 2 degrees C/h. Cooling was stopped when shivering intensity no longer increased with further core cooling. The gain of shivering was the slope of oxygen consumption versus core temperature regression. In Study 1, sweating and vasoconstriction thresholds were similar on both days. In contrast, shivering threshold decreased 0.3 +/- 0.3 degrees C, P = 0.004, on the dantrolene day. In Study 2, dantrolene decreased the shivering threshold from 36.7 +/- 0.2 to 36.3 +/- 0.3 degrees C, P = 0.01 and systemic gain from 353 +/- 144 to 211 +/- 93 mL.min(-1).degrees C(-1), P = 0.02. Thus, dantrolene substantially decreased the gain of shivering, but produced little central thermoregulatory inhibition. ⋯ Dantrolene substantially decreases the gain of shivering but produces relatively little central thermoregulatory inhibition. It thus seems unlikely to prove more effective than conventional muscle relaxants for treatment of life-threatening hyperthermia.
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Anesthesia and analgesia · May 2004
Comparative Study Clinical TrialReducing hemostatic activation during cardiopulmonary bypass: a combined approach.
Interventions such as heparin-coated circuits, epsilon-aminocaproic acid, and reduced shed blood reinfusion have shown mixed results when applied individually for limiting hemostatic activation during cardiopulmonary bypass (CPB). We compared coagulation and fibrinolytic activation during conventional CPB (control) (CTRL) using noncoated circuits, no antifibrinolytics, and open cardiotomy with a combined strategy (HAC) that used heparin-coated circuits, epsilon-aminocaproic acid, and closed cardiotomy. Blood samples were drawn before, during, and after CPB for primary coronary bypass grafting surgery from 9 CTRL patients and 10 HAC patients. Thrombin-antithrombin complex and fibrinopeptide A levels (markers of thrombin and fibrin generation) were reduced in the HAC versus CTRL group after 30 min of CPB (P < 0.05). Average tissue plasminogen activator (tPA) levels were significantly lower in the HAC group by 30 min on CPB (P < 0.05), resulting in preservation of plasminogen activator inhibitor (PAI)-1 during CPB (P < 0.05). D-Dimer, a measure of intravascular fibrin formation and removal, was reduced in the HAC group during and after CPB (P < 0.005). Overall, the combined strategy was associated with a reduction in CPB-induced increases in markers of thrombin generation, fibrin formation, tPA release, and fibrin degradation and better preservation of PAI-1. ⋯ A combined approach during cardiopulmonary bypass (CPB) that uses heparin-coated circuits, epsilon-aminocaproic acid, and limited reinfusion of shed pericardial blood is associated with reduced activation of the coagulation and fibrinolytic systems that typically occurs during conventional CPB.
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The testing of pulse oximeter probes is generally limited to the integrity of the electrical circuit and does not include the optical properties of the probes. Few pulse oximeter testers evaluate the accuracy of both the monitor and the probe. We designed a study to compare the accuracy of nonproprietary probes (OSS Medical) designed for use with Nellcor, Datex-Ohmeda, and Criticare pulse oximeter monitors with that of their corresponding proprietary probes by using a commercial off-the-shelf pulse oximeter tester (Index). The Index pulse oximeter tester does include testing of the optical properties of the pulse oximeter probes. The pulse oximeter tester was given a controlled input that simulated acute apnea. Desaturation curves were automatically recorded from the pulse oximeter monitors with a data-collection computer. Comparisons between equivalent proprietary and nonproprietary probes were performed. Data were analyzed by using univariate and multivariate general linear model analysis. Five OSS Medical probe models were statistically better than the equivalent proprietary probes. The remainder of the probes were statistically similar. Comparative and simulation studies can have significant advantages over human studies because they are cost-effective, evaluate equipment in a clinically relevant scenario, and pose no risk to patients, but they are limited by the realism of the simulation. ⋯ We studied the performance of pulse oximeter probes in a simulated environment. Our results show significant differences between some probes that affect the accuracy of measurement.
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Anesthesia and analgesia · May 2004
Trends in the practice of parental presence during induction of anesthesia and the use of preoperative sedative premedication in the United States, 1995-2002: results of a follow-up national survey.
Both parental presence during induction of anesthesia and sedative premedication are currently used to treat preoperative anxiety in children. A survey study conducted in 1995 demonstrated that most children are taken into the operating room without the benefit of either of these two interventions. In 2002 we conducted a follow-up survey study. Five thousand questionnaires were mailed to randomly selected physician members of the American Society of Anesthesiologists. Mailings were followed by a nonresponse bias assessment. Twenty-seven percent (n = 1362) returned the questionnaire after 3 mailings. We found that a significantly larger proportion of young children undergoing surgery in the United States were reported to receive sedative premedication in 2002 as compared with 1995 (50% vs 30%, P = 0.001). We also found that in 2002 there was significantly less geographical variability in the use of sedative premedication as compared with the 1995 survey (F = 8.31, P = 0.006). Similarly, we found that in 2002 parents of children undergoing surgery in the United States were allowed to be present more often during induction of anesthesia as compared with 1995 (chi(2) = 26.3, P = 0.0001). Finally, similar to our findings in the 1995 survey, midazolam was uniformly selected most often to premedicate patients before surgery. ⋯ Over the past 7 yr there have been significant increases in the number of anesthesiologists who use preoperative sedative premedication and parental presence for children undergoing surgery.