Anesthesia and analgesia
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Anesthesia and analgesia · Apr 1998
Randomized Controlled Trial Comparative Study Clinical TrialThe use of a selective axillary nerve block for outpatient hand surgery.
Although no guidelines concerning discharge criteria after axillary plexus block are available, many institutions consider recovery of motor function as a critical factor. With the midhumeral approach, the four main nerves of the upper extremity can be blocked separately using a peripheral nerve stimulator. The aim of this double-blind study was to block the radial (R) and musculocutaneous (MC) nerves with lidocaine, and the median (M) and ulnar (U) nerves with bupivacaine to recover motor function of the elbow and wrist more rapidly while maintaining long-lasting postoperative analgesia at the operative site. Patients undergoing surgery for Dupuytren's contracture were randomized into two groups in a double-blind fashion: in the control group (n = 17), each of the four nerves was infiltrated with 10 mL of a mixture of 2% lidocaine and 0.5% bupivacaine, whereas in the selective group (n = 17), the R and MC nerves were blocked with 10 mL of 2% lidocaine each and the M and U nerves were blocked with 10 mL of 0.5% bupivacaine each. Recovery of motor block was significantly faster in the selective group (231 +/- 91 vs 466 +/- 154 min). However, time to first sensation of pain was not different between groups (707 +/- 274 vs 706 +/- 291 min). In conclusion, this new approach at the midhumeral level enables the anesthesiologist to selectively administer local anesthetics on different nerves. ⋯ In outpatients undergoing surgery for Dupuytren's contracture, a midhumeral block was used with the musculocutaneous and radial nerves blocked by lidocaine and the median and ulnar nerves blocked with bupivacaine. Recovery of motor function and time to discharge were shorter compared with patients who received the mixture on all four nerves.
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Anesthesia and analgesia · Apr 1998
Randomized Controlled Trial Clinical TrialPropofol concentration required for endotracheal intubation with a laryngoscope or fiberscope and its interaction with fentanyl.
The administration of fentanyl with propofol reduces the blood concentration of propofol required to achieve adequate anesthesia for tracheal intubation. However, different intubation procedures have variable intensities of noxious stimulation and may require different levels of anesthesia. The goal of this study was to determine the propofol blood concentration at which 50% of patients did not respond to stimulation (Cp50) for laryngoscopy, intubation with a laryngoscope, insertion of a slotted oral-pharyngeal airway (Ovassapian airway), and intubation with a fiberscope when administered in conjunction with fentanyl. Patients undergoing elective surgery were given varying amounts of propofol or propofol with fentanyl, and their responses to the four procedures listed above were assessed. These experiments demonstrated that the propofol concentration required for intubation with a laryngoscope was similar to that for intubation with a fiberscope, and that the required level was reduced by fentanyl. Hemodynamic responses to intubation were lower with a fiberscope than with a laryngoscope. We conclude that almost the same concentrations of propofol or fentanyl are necessary for suppressing both of the somatic responses to tracheal intubation with a fiberscope or a laryngoscope. Hemodynamic responses were attenuated more during intubation with a fiberscope. ⋯ The propofol blood concentrations at which 50% of patients did not respond to stimulation for laryngoscopy, tracheal intubation with a laryngoscope, and tracheal intubation with a fiberscope were 10.9, 19.6, and 19.9 microg/mL, respectively. These were reduced by fentanyl. Hemodynamic responses to intubation were less with a fiberscope than with a laryngoscope.
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Anesthesia and analgesia · Apr 1998
The impact of postoperative pain on the development of postoperative delirium.
We performed a prospective observational study to examine the role of postoperative pain and its treatment on the development of postoperative delirium. Pain was measured in direct patient interviews using a visual analog scale (VAS) and was assessed for pain at rest, pain with movement, and maximal pain over the previous 24 h. Postoperative delirium was diagnosed during these interviews by using the confusion assessment method (CAM) and/or by using data from the medical record and the hospital's nursing intensity index. The method of postoperative analgesia, type of opioid, and cumulative opioid dose were also recorded. After controlling for known preoperative risk factors for delirium (age, alcohol abuse, cognitive function, physical function, serum chemistries, and type of surgery), higher pain scores at rest was associated with an increased risk of delirium over the first 3 postoperative days (adjusted risk ratio 1.20, P = 0.04). Pain with movement and maximal pain were not associated with delirium. Method of postoperative analgesia, type of opioid, and cumulative opioid dose were not associated with an increased risk of delirium. We conclude that more effective control of postoperative pain reduces the incidence of postoperative delirium. ⋯ We performed daily interviews in a large population of patients undergoing noncardiac surgery to measure their level of pain and development of delirium. We found an association between higher pain levels at rest and the development of delirium. Our results suggest that better control of postoperative pain may reduce this serious complication.
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Anesthesia and analgesia · Apr 1998
Comparative StudyCardiovascular and central nervous system effects of intravenous levobupivacaine and bupivacaine in sheep.
Commercially available bupivacaine is an equimolar mixture of R(+)- and S(-)-bupivacaine. S(-)-bupivacaine (i.e., levobupivacaine) is currently undergoing preclinical evaluation. Cross-over studies with i.v. levobupivacaine and bupivacaine were conducted in two groups of seven conscious sheep. Doses were chosen to avoid convulsions (smaller dose 6.25-37.5 mg/min) or to be potentially toxic (larger dose 75-200 mg/3 min). In subconvulsive doses, both drugs produced similar time- and dose-dependent depression of left ventricular systolic contractility (dP/dt(max)). Convulsions occurred consistently with > or = 75 mg of bupivacaine and > or = 100 mg of levobupivacaine, producing an abrupt reversal of dP/dt(max) depression. Subconvulsive doses produced minor cardiovascular effects on heart rate and blood pressure, whereas both were increased by convulsions. Cardiac output and myocardial blood flow were decreased with larger doses of both drugs. Doses > 75 mg of bupivacaine or > 100 mg of levobupivacaine induced QRS widening and ventricular arrhythmias, but significantly fewer and less deleterious arrhythmias were induced by levobupivacaine. Three animals died after 150, 150, and 200 mg of bupivacaine from the sudden onset of ventricular fibrillation. These doses of levobupivacaine produced nonfatal arrhythmias that automatically returned to sinus rhythm. We conclude that levobupivacaine could offer a greater margin of clinical safety than bupivacaine. ⋯ Levobupivacaine comprises 50% of commercially available bupivacaine and is being considered for use in its own right. Local anesthetics can cause toxicity to the cardiovascular and central nervous systems. As a part of a preclinical evaluation of levobupivacaine, this study compared the toxic effects of levobupivacaine and bupivacaine in sheep.
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Anesthesia and analgesia · Apr 1998
The relationship of soluble adhesion molecule concentrations in systemic and jugular venous serum to injury severity and outcome after traumatic brain injury.
Adhesion molecules control the migration of leukocytes into tissue after injury. This may result in further cellular damage. We hypothesized that altered serum concentrations of soluble intercellular adhesion molecule (sICAM)-1 and soluble L-selectin (sL-selectin) after traumatic brain injury would correlate with injury severity and neurological outcome. We investigated serum concentrations of sICAM-1 and sL-selectin in 22 patients with traumatic brain injury admitted to the intensive care unit. The Glasgow Coma Scale (GCS) score and Injury Severity Score were recorded. Paired arterial and jugular venous blood samples were taken on admission and 24, 48, and 96 h after injury. Mean systemic and jugular venous concentrations of sICAM-1 were normal on admission but became significantly increased by 96 h (P = 0.018). sL-selectin concentrations of injured patients were markedly below those of controls at all time points (P < 0.001). There were no significant differences between jugular venous and arterial concentrations of either sICAM-1 or sL-selectin. Serum sICAM-1 was significantly related to neurological outcome (P < 0.001) and to the GCS score (P < 0.001). These changes in adhesion molecule expression after acute brain injury may be important in the pathophysiology of secondary injury. The highly significant relationship between serum sICAM-1 and neurological outcome suggests that the inflammatory response to injury may be detrimental. Drugs that antagonize the actions of the adhesion molecules may have a role in therapy after traumatic brain injury. ⋯ This observational study shows that there is a strong association between soluble intercellular adhesion molecule-1 in serum and poor neurological outcome after traumatic brain injury. This suggests that inflammation after brain injury may worsen the prognosis and that therapies directed against this inflammation may prove useful.