Anesthesia and analgesia
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Anesthesia and analgesia · Jan 2004
Randomized Controlled Trial Comparative Study Clinical TrialMechanical versus manual ventilation via a face mask during the induction of anesthesia: a prospective, randomized, crossover study.
One approach to make ventilation safer in an unprotected airway has been to limit tidal volumes; another one might be to limit peak airway pressure, although it is unknown whether adequate tidal volumes can be delivered. Accordingly, the purpose of this study was to evaluate the quality of automatic pressure-controlled ventilation versus manual circle system face-mask ventilation regarding ventilatory variables in an unprotected airway. We studied 41 adults (ASA status I-II) in a prospective, randomized, crossover design with both devices during the induction of anesthesia. Respiratory variables were measured with a pulmonary monitor (CP-100). Pressure-controlled mask ventilation versus circle system ventilation resulted in lower (mean +/- SD) peak airway pressures (10.6 +/- 1.5 cm H(2)O versus 14.4 +/- 2.4 cm H(2)O; P < 0.001), delta airway pressures (8.5 +/- 1.5 cm H(2)O versus 11.9 +/- 2.3 cm H(2)O; P < 0.001), expiratory tidal volume (650 +/- 100 mL versus 680 +/- 100 mL; P = 0.001), minute ventilation (10.4 +/- 1.8 L/min versus 11.6 +/- 1.8 L/min; P < 0.001), and peak inspiratory flow rates (0.81 +/- 0.06 L/s versus 1.06 +/- 0.26 L/s; P < 0.001) but higher inspiratory time fraction (48% +/- 0.8% versus 33% +/- 7.7%; P < 0.001) and end-tidal carbon dioxide (34 +/- 3 mm Hg versus 33 +/- 4 mm Hg; not significant). We conclude that in this model of apneic patients with an unprotected airway, pressure-controlled ventilation resulted in reduced inspiratory peak flow rates and peak airway pressures when compared with circle system ventilation, thus providing an additional patient safety effect during mask ventilation. ⋯ In this model of apneic patients with an unprotected airway, pressure-controlled ventilation resulted in reduced inspiratory peak flow rates and lower peak airway pressures when compared with circle system ventilation, thus providing an additional patient safety effect during face-mask ventilation.
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Anesthesia and analgesia · Jan 2004
Randomized Controlled Trial Comparative Study Clinical TrialAssessing analgesia in single and repeated administrations of propacetamol for postoperative pain: comparison with morphine after dental surgery.
We conducted this double-blinded, randomized study to assess the analgesic effect of repeated administrations of paracetamol, administered as propacetamol, an injectable prodrug formulation of paracetamol, and to compare this with the analgesic effects of morphine. Patients experiencing moderate to severe pain after elective surgical removal of bone-impacted third-molar teeth under general anesthesia were randomly assigned to receive IV propacetamol 2 g (n = 31), IM morphine 10 mg (n = 30), or placebo (n = 34). Five hours later, the treatments were readministered at half of the previous dosages. Standard measures of analgesia were collected repeatedly for 10 h. Propacetamol and morphine were significantly more effective than placebo in all primary measures of analgesia over 5 h after the first administration and globally over 10 h (first and second administrations). After the first dose, 21 of the 34 patients in the placebo group required rescue medication, compared with 6 of the 31 in the propacetamol group (P < 0.0009) and 4 of the 30 in the morphine group (P < 0.0001). No statistically or clinically significant differences were found between propacetamol and morphine for any sum or peak measures of analgesia. No serious adverse events were reported; adverse events were significantly less frequent in the propacetamol group than in the morphine group (P < 0.027). Propacetamol administered IV in repeated doses (2 g followed by 1 g) has a significant analgesic effect that is indistinguishable from that of morphine administered IM (10 mg followed by 5 mg) after dental surgery, with better tolerability. ⋯ After moderately painful surgical procedures, IV paracetamol, administered as propacetamol, may be an asset in the control of acute postoperative pain.
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Anesthesia and analgesia · Jan 2004
Randomized Controlled Trial Clinical TrialAcupuncture decreases somatosensory evoked potential amplitudes to noxious stimuli in anesthetized volunteers.
The effect of acupuncture on pain perception is controversial. Because late amplitudes of somatosensory evoked potentials (SEPs) to noxious stimuli are thought to correlate with the subjective experience of pain intensity, we designed this study to detect changes of these SEPs before and after acupuncture in a double-blinded fashion. Sixteen volunteers were anesthetized by propofol and exposed to painful electric stimuli to the right forefinger. Then, blinded to the research team, the acupuncture group (n = 8) was treated with electric needle acupuncture over 15 min at analgesic points of the leg, whereas the sham group (n = 8) received no treatment. Thereafter, nociceptive stimulation was repeated. SEPs were recorded during each noxious stimulation from the vertex Cz, and latencies and amplitudes of the N150 and P260 components were analyzed by analysis of variance. P260 amplitudes decreased from 4.40 +/- 2.76 microV (mean +/- SD) before treatment to 1.67 +/- 1.21 microV after treatment (P < 0.05), whereas amplitudes of the sham group remained unchanged (2.64 +/- 0.94 microV before versus 2.54 +/- 1.54 microV after treatment). In conclusion, this double-blinded study demonstrated that electric needle acupuncture, as compared with sham treatment, significantly decreased the magnitudes of late SEP amplitudes with electrical noxious stimulation in anesthetized subjects, suggesting a specific analgesic effect of acupuncture. ⋯ This double-blinded study demonstrates that electric needle acupuncture, as compared with sham treatment, significantly decreases the magnitudes of late somatosensory evoked potential amplitudes with electrical noxious stimulation in anesthetized subjects, suggesting a specific analgesic effect of acupuncture.
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Anesthesia and analgesia · Jan 2004
Randomized Controlled Trial Comparative Study Clinical TrialSpinal 2-chloroprocaine: a dose-ranging study and the effect of added epinephrine.
With the availability of preservative- and antioxidant-free 2-chloroprocaine (2-CP), there may be an acceptable short-acting alternative to lidocaine for spinal anesthesia. We examined the safety, dose-response characteristics, and effects of epinephrine with spinal 2-CP. Six volunteers per group were randomized to receive 30, 45, or 60 mg of spinal 2-CP with and without epinephrine. Intensity and duration of sensory and motor blockade were assessed. When 11 of the 18 volunteers complained of vague, nonspecific flu-like symptoms, breaking of the blind revealed that all spinal anesthetics associated with the flu-like symptoms contained epinephrine. There were no complaints of flu-like symptoms in the volunteers who received 2-CP without epinephrine. No further spinal anesthetics containing epinephrine were administered, resulting in 29 anesthetics (11 with epinephrine, 18 without epinephrine.) Plain 2-CP demonstrated a dose-dependent increase in peak block height and duration of effect at all variables except time to 2-segment regression and time to regression to T10. Time to complete sensory regression with plain 2-CP was 98 +/- 20, 116 +/- 15, and 132 +/- 23 min, respectively. 2-CP with epinephrine produced times to complete sensory regression of 153 +/- 25, 162 +/- 33, and 148 +/- 29 min, respectively. Preservative and antioxidant free 2-CP can be used effectively for spinal anesthesia in doses of 30-60 mg. Epinephrine is not recommended as an adjunct because of the frequent incidence of side effects. ⋯ Hyperbaric spinal 2-chloroprocaine is effective and has an anesthetic profile appropriate for use in the surgical outpatient over the dose range of 30-60 mg without signs of transient neurologic symptoms. The addition of epinephrine is not recommended because of the frequent incidence of side effects.
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Anesthesia and analgesia · Jan 2004
Randomized Controlled Trial Comparative Study Clinical TrialSpinal 2-chloroprocaine: a comparison with lidocaine in volunteers.
Subarachnoid lidocaine has been the anesthetic of choice for outpatient spinal anesthesia. However, its use is associated with transient neurologic symptoms (TNS). Preservative-free formulations of 2-chloroprocaine are now available and may compare favorably with lidocaine for spinal anesthesia. In this double-blinded, randomized, crossover study, we compared spinal chloroprocaine and lidocaine in 8 volunteers, each receiving 2 spinal anesthetics: 1 with 40 mg 2% lidocaine and the other with 40 mg 2% preservative-free 2-chloroprocaine. Pinprick anesthesia, tolerance to transcutaneous electrical stimulation and thigh tourniquet, motor strength, and a simulated discharge pathway were assessed. Chloroprocaine produced anesthetic efficacy similar to lidocaine, including peak block height (T8 [T5-11] versus T8 [T6-12], P = 0.8183) and tourniquet tolerance (46 +/- 6 min versus 38 +/- 24 min, P = 0.4897). Chloroprocaine anesthesia resulted in faster resolution of sensory (103 +/- 13 min versus 126 +/- 16 min, P = 0.0045) and more rapid attainment of simulated discharge criteria (104 +/- 12 min versus 134 +/- 14 min, P = 0.0007). Lidocaine was associated with mild to moderate TNS in 7 of 8 subjects; no subject complained of TNS with chloroprocaine (P = 0.0004). We conclude that the anesthetic profile of chloroprocaine compares favorably with lidocaine. Reliable sensory and motor blockade with predictable duration and minimal side effects make chloroprocaine an attractive choice for outpatient spinal anesthesia. ⋯ The spinal anesthetic profile of chloroprocaine (40 mg) compares favorably with the same dose of spinal lidocaine. Reliable sensory and motor blockade with predictable duration and minimal side effects and without signs of transient neurological symptoms make chloroprocaine an attractive choice for outpatient spinal anesthesia.