Anesthesia and analgesia
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Anesthesia and analgesia · Jun 2002
Randomized Controlled Trial Comparative Study Clinical TrialLidocaine iontophoresis versus eutectic mixture of local anesthetics (EMLA) for IV placement in children.
Pain during venipuncture is a major source of concern to children and their caretakers. Iontophoresis is a novel technique that uses an electrical current to facilitate movement of solute ions (lidocaine) across the stratum corneum barrier to provide dermal analgesia. In this study, we compared dermal analgesia provided by lidocaine iontophoresis and eutectic mixture of local anesthetics (EMLA). After informed consent, 26 children, aged 7-16 yr, who required venous cannulation on multiple occasions, were enrolled in this prospective, randomized, crossover study to receive EMLA and iontophoresis on separate occasions. During a third session, each subject received his or her preferred treatment. Pain during venipuncture was assessed by the subject, parent, observer, and technician performing the procedure, by use of a 100-mm visual analog scale. The observer also used the Children's Hospital of Eastern Ontario Pain Scale to rate the subject's pain. Ratings of subject satisfaction were also assessed. There were no significant differences between the two groups in the subject-rated visual analog scale or the Children's Hospital of Eastern Ontario Pain Scale scores. Eleven (50%; 95% confidence interval [CI], 31%-69%) of the 22 subjects who completed both sessions preferred iontophoresis. Five subjects (23%; 95% CI, 10%-44%), including two who did not tolerate treatment with iontophoresis, preferred EMLA, and six (27%; 95% CI, 13%-48%) had no preference for the intervention to provide dermal analgesia. We conclude that lidocaine iontophoresis provides similar pain relief for insertion of IV catheters as EMLA and is a useful noninvasive alternative to establish dermal analgesia for venous cannulation. ⋯ Iontophoresis is a technique that uses an electrical current to facilitate movement of solute ions (lidocaine) across the stratum corneum barrier to provide dermal analgesia. Lidocaine iontophoresis provides similar pain relief for insertion of IV catheters as eutectic mixture of local anesthetics and is a useful noninvasive alternative to establish dermal analgesia for venous cannulation.
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Anesthesia and analgesia · Jun 2002
Randomized Controlled Trial Clinical TrialEpidural morphine delays the onset of tourniquet pain during epidural lidocaine anesthesia.
We conducted a randomized, double-blinded study to examine the onset time of tourniquet pain during epidural lidocaine anesthesia either with or without morphine in the epidural solution. Forty-five patients undergoing knee surgery with a thigh tourniquet were randomly allocated into 3 groups of 15 patients each: epidural morphine (EM; epidural administration of 17 mL of 2% lidocaine plus 2 mg of morphine, followed by IV injection of 0.2 mL of normal saline), IV morphine (IVM; 17 mL of 2% lidocaine plus 0.2 mL of normal saline, followed by IVM 2 mg IV), and control (17 mL of 2% lidocaine plus 0.2 mL of normal saline, followed by 0.2 mL of normal saline IV). The onset time of tourniquet pain was recorded. The level of sensory block was determined by the pinprick method at the occurrence of tourniquet pain. Hemodynamic changes and side effects of EM were also recorded. The onset time of tourniquet pain from both the epidural injection and the tourniquet inflation were significantly longer in the EM group (103 +/- 15 min and 80 +/- 15 min, respectively) compared with the IVM group (74 +/- 12 min and 50 +/- 12 min, respectively; P < 0.05) and the Control group (67 +/- 9 min and 45 +/- 9 min, respectively; P < 0.05). The level of sensory block at the onset of tourniquet pain and hemodynamic changes were not different among the three groups. Only two and three patients in the EM group complained of nausea/vomiting and pruritus, respectively. Respiratory depression was not observed in any patient. We conclude that epidural injection of the mixture of 2 mg of morphine and 2% lidocaine solution delayed the onset of tourniquet pain during epidural lidocaine anesthesia without significant morphine-related side effects. ⋯ We examined the effect of epidural morphine on the onset of tourniquet pain during epidural lidocaine anesthesia. We found that the addition of 2 mg of morphine to epidural 2% lidocaine significantly delayed the onset of tourniquet pain without increasing morphine-related side effects.
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Anesthesia and analgesia · Jun 2002
Randomized Controlled Trial Clinical TrialThe hypnotic and analgesic effects of oral clonidine during sevoflurane anesthesia in children: a dose-response study.
Although clonidine has both hypnotic and analgesic actions, the dose relationship for each actions is still unknown in a clinical setting when clonidine is used as a premedication in children. We studied 80 ASA physical status I children (age range, 3-8 yr). Subjects were randomly divided into two groups (minimum alveolar anesthetic concentration [MAC]-Awake group, n = 40; MAC-Tetanus group, n = 40). Each patient received one dose of clonidine from 1 to 5 microg/kg orally, 100 min before arrival at the operating room. Anesthesia was induced and maintained with sevoflurane in oxygen and air. Before tracheal intubation, end-tidal sevoflurane was decreased stepwise by 0.2% at the start of 1.2%, a verbal command was given to the patients, and MAC-awake was determined in each patient. We also investigated MAC-tetanus, determined with transcutaneous electric tetanic stimulations, after tracheal intubation in each patient by observing the motor response to a transcutaneous electric tetanic stimulus to the ulnar nerve at a sevoflurane concentration decreased stepwise by 0.25% at the start of 2.75%. The initial reduction in MAC-tetanus was not as steep as that in MAC-awake. Clonidine reduced MAC-tetanus by 40% at the maximal dose of 5 microg/kg, whereas MAC-awake was already reduced by 50% at 2 microg/kg. We conclude that separate dose-response relationships for oral clonidine are present regarding the hypnotic and analgesic effects in children undergoing sevoflurane anesthesia. ⋯ Separate dose-response relationships for oral clonidine were found regarding the hypnotic and analgesic effects in children undergoing sevoflurane anesthesia.
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Anesthesia and analgesia · Jun 2002
Pressure support compared with controlled mechanical ventilation in experimental lung injury.
It has been suggested that, in acute lung injury (ALI), spontaneous breathing activity may increase oxygenation because of an improvement of ventilation-perfusion distribution. Pressure support ventilation (PSV) is one of the assisted spontaneous breathing modes often used in critical care medicine. We sought to determine the prolonged effects of PSV on gas exchange in experimental ALI. We hypothesized that PSV may increase oxygenation because of an improvement in ventilation-perfusion distribution. Thus, ALI was induced in 20 pigs by using repetitive lung lavage. Thereafter, the animals were randomized to receive either PSV with a pressure level set to achieve a tidal volume >4 mL/kg and a respiratory rate <40 min(-1) (n = 10) or controlled mechanical ventilation (CMV) with a tidal volume of 10 mL/kg and a respiratory rate of 20 min(-1) (n = 10). Positive end-expiratory pressure was set at 10 cm H(2)O in both groups. Blood gas analyses and determination of ventilation-perfusion (.V(A)/.Q) distribution were performed at the onset of ALI and after 2, 4, 8, and 12 h. The main result was an improvement of oxygenation because of a decrease of pulmonary shunt and an increase of areas with normal .V(A)/.Q ratios during PSV (P < 0.005). However, during CMV, a more pronounced reduction of shunt was observed compared with PSV (P < 0.005). We conclude that, in this model of ALI, PSV improves gas exchange because of a reduction of .V(A)/.Q inequality. However, improvements in .V(A)/.Q distribution may be more effective with CMV than with PSV. ⋯ Assisted spontaneous breathing may have beneficial effects on gas exchange in acute lung injury. We tested this hypothesis for pressure support ventilation in an animal model of acute lung injury. Our results demonstrate that pressure support does not necessarily provide better gas exchange than controlled mechanical ventilation.
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Anesthesia and analgesia · Jun 2002
An analysis of responses to levosimendan in the pulmonary vascular bed of the cat.
Calcium-sensitizing drugs, such as levosimendan, are a novel class of drug therapy for heart failure. We investigated the hypothesis that levosimendan is a pulmonary vasodepressor mediated through inhibition of phosphodiesterase, adenosine triphosphate (ATP)-dependent potassium channels, or both. We investigated responses to the calcium sensitizer levosimendan in the pulmonary vascular bed of the cat under conditions of controlled pulmonary blood flow and constant left atrial pressure when lobar arterial pressure was increased to a high steady level with the thromboxane A(2) analog U-46619. Under increased-tone conditions, levosimendan caused dose-related decreases in lobar arterial pressure without altering systemic arterial and left atrial pressure. Responses to levosimendan were significantly attenuated, although not completely, after the administration of U-37883A, a vascular selective nonsulfonylurea ATP-sensitive K(+)-channel-blocking drug. Responses to levosimendan were not significantly different after the administration of the nitric oxide synthase inhibitor L-N(5)-(1-iminoethyl)-ornithine or the cyclooxygenase inhibitor sodium meclofenamate or when lung ventilation was interrupted. These data show that levosimendan has significant vasodilator activity in the pulmonary vascular bed of the cat. They also suggest that pulmonary vasodilator responses to levosimendan are partially dependent on activation of ATP-sensitive K(+) channels and independent of the synthesis of nitric oxide, activation of cyclooxygenase enzyme, or changes in bronchomotor tone in the pulmonary vascular bed of the cat. ⋯ Calcium-sensitizing drugs, such as levosimendan, are a novel class of drug therapy for heart-failure treatment. The lung circulation affects both right- and left-sided heart failure. Levosimendan decreased lobar arterial pressure via a partial K(+)(ATP) (potassium channel sensitive to intracellular adenosine triphosphate levels)-dependent mechanism. These data suggest that, in addition to calcium-sensitizing activity, levosimendan decreases pulmonary resistance, which may also aid in the treatment of heart failure.