Anesthesia and analgesia
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Anesthesia and analgesia · Jan 2004
Clinical TrialCapnography in non-tracheally intubated emergency patients as an additional tool in pulse oximetry for prehospital monitoring of respiration.
Victims of minor trauma transported by paramedic-based rescue systems are usually monitored with pulse oximetry. Under the difficult surroundings of prehospital trauma care, pulse oximeters show considerable periods of malfunction. We tested the hypothesis that capnography is a good, easy to use tool for monitoring in nonintubated trauma victims. Seventy nonintubated trauma victims were included in this study. Vital variables and number and time of malfunctions were sampled for oximeter and capnometer recordings. Total number of alerts (63 versus 10), number of alerts per patient (3.3 [1.9] versus 0.3 [0.9]) (mean [SD]), total time of malfunction (191.5 [216.7] s versus 11.8 [40.2] s), time of malfunction per alarm (58.3 [71.4] s versus 5.5 [14.6] s), and the percentage of malfunction time during transport (13.2% [15.3%] versus 0.8% [2.8%]) differed significantly (P < 0.01) between oximetry and capnography. Although pulse oximetry is a standard method of monitoring in emergency care, we found capnography to be helpful as a monitoring device. We consequently recommend the use of capnography on transport as an additional monitoring tool to reduce periods lacking supervision of the vital variables. ⋯ Capnography is a useful tool to improve respiratory monitoring in nonintubated trauma victims on emergency transport and an easy to use supplement to pulse oximetry.
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Anesthesia and analgesia · Jan 2004
Orthostatic hypotension occurs frequently in the first hour after anesthesia.
Symptoms of orthostatic intolerance are common after general anesthesia and are associated with an increased risk of postoperative morbidity. The contribution of orthostatic hypotension (OH) has not been well defined. We conducted a head-up tilt test on patients after general anesthesia for minor surgery to assess the incidence of and risk factors for OH after general anesthesia. One-hundred-four patients were enrolled and were prospectively divided into four groups: older female, older male, young female, and young male. The incidence of OH was 76.0%, 72.0%, 45.5%, and 62.5% respectively and was associated with increasing age (P < 0.05) and posttest dizziness (P < 0.05). Body mass index, preoperative blood pressure, ASA class, anesthetic duration, IV fluid administration, and use of analgesics and antiemetics in the postanesthetic care unit were not different in subjects who demonstrated OH compared with those with a normotensive response. Subjects with OH after general anesthesia did not increase their heart rate and diastolic blood pressure with a head-up tilt which may have been caused by persistent effects of anesthetics on reflex cardiovascular control and/or bedrest-induced dysregulation of reflex cardiovascular control. We conclude that OH is common after general anesthesia for minor surgery and may be the major cause of postoperative orthostatic intolerance. ⋯ Orthostatic hypotension, a failure to maintain blood pressure on assuming an upright posture, is common after general anesthesia for minor surgery and may be the major cause of postoperative orthostatic intolerance.
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Anesthesia and analgesia · Jan 2004
Clinical TrialQuantitative and selective evaluation of differential sensory nerve block after transdermal lidocaine.
We evaluated the effect of transdermal lidocaine on differential sensory nerve block in 15 healthy volunteers. Lidocaine 10% gel was applied topically to a forearm and covered with a plastic film. Three types of sensory nerve fibers (Abeta, Adelta, and C fibers) were evaluated with a series of 2000-, 250-, and 5-Hz stimuli using current perception threshold (CPT) testing. Sensations of touch, pinprick, cold, and warmth were also measured. These measurements were made before the topical lidocaine (baseline), 60 min after the draping (T0), and at 1-h intervals until 5 h after T0 (T1 to T5). A significant increase in CPT compared with baseline was observed until T2 at 5 Hz and T4 at 250 Hz, whereas the increase in CPT at 2000 Hz continued throughout the study period. All subjects experienced the disappearance of pinprick and cold sensations, whereas touch and warmth sensations were detectable during the study period. We conclude that when lidocaine is applied transdermally, the sensitivity of nerves to local anesthetics is proportional to the axon diameters. However, pinprick and cold sensation are affected more strongly than other sensations at receptor sites. ⋯ We evaluated the effect of transdermal lidocaine on differential sensory nerve block in healthy volunteers. Our results show that the sensitivity of nerves to local anesthetics is proportional to the axon diameter.
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Anesthesia and analgesia · Jan 2004
Clinical TrialAssessing propofol induction of anesthesia dose using bispectral index analysis.
In this study we sought to determine the propofol requirement and hemodynamic effects as guided by bispectral index (BIS) analysis during induction of anesthesia. Sixty patients were enrolled in this study. Propofol, 2 mg/kg, was given to Group I for induction. Propofol was administered for induction until loss of response to verbal commands and until BIS values were around 50 to Groups II and III. After induction, the smallest BIS value was different in Group I. Decreases in total propofol dose were 36% and 43% in Groups II and III respectively as compared with Group I. The dose of propofol assessed by BIS analysis results in an important reduction of propofol requirement without side effects. ⋯ Hypotension during induction of anesthesia with propofol is common. This study has shown that propofol requirement assessed by bispectral index analysis during anesthesia induction may decrease the dose and side effects and provide for satisfactory depth of anesthesia.
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Anesthesia and analgesia · Jan 2004
Risperidone and exaggerated hypotension during a spinal anesthetic.
Antipsychotic medications are often continued through pregnancy and may have important anesthetic interactions. For example, risperidone is an antipsychotic medication with therapeutic effects mediated by dopaminergic and serotonergic antagonism. However, it also possesses potent alpha-1 adrenergic antagonism. Here we report a case of a parturient with bipolar disease, controlled with lithium and risperidone, undergoing a spinal anesthetic for a cesarean delivery. The parturient developed exaggerated hypotension, refractory to conventional treatment with ephedrine and IV fluids, that eventually responded to large doses of phenylephrine. Risperidone alpha-antagonism should be a consideration for any patient receiving this medication during neuraxial anesthesia. Treatment of significant and refractory hypotension with an alpha-1 agonist such as phenylephrine may be warranted. ⋯ Parturients receiving neuraxial blocks may be taking antipsychotic medications. Although the therapeutic effects of antipsychotic medications are mediated by dopaminergic and serotonergic antagonism, many possess alpha-adrenergic antagonist properties. We report a case of exaggerated hypotension during a spinal anesthetic for cesarean delivery that may have been a result of the alpha-adrenergic antagonism of risperidone.