Anesthesia and analgesia
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Anesthesia and analgesia · May 1999
Randomized Controlled Trial Comparative Study Clinical TrialThe effect of intravenous lactated Ringer's solution versus 0.9% sodium chloride solution on serum osmolality in human volunteers.
Animal studies have shown that large volumes of IV lactated Ringer's solution (LR) decrease serum osmolality, thereby increasing cerebral water. These studies have led to recommendations to limit LR to avoid cerebral edema in neurosurgical patients. Eighteen healthy human volunteers aged 20-48 yr received 50 mL/kg LR over 1 h on one occasion and 0.9% sodium chloride (NS) on another. Venous samples were taken at baseline (T1), at infusion end (T2), and 1 h after T2 (T3). Time until first urination was noted. With LR, serum osmolality decreased by 4+/-3 mOsm/kg from T1 to T2 and increased insignificantly with NS. At T3, osmolality returned almost to baseline in the LR group. Blood pH increased from T1 to T2 with LR by 0.04+/-0.04 and decreased with NS by 0.04+/-0.04. These pH changes persisted at T3. Subjective mental changes occurred only with NS. Abdominal discomfort was more common with NS. Time until first urination was longer with NS (106+/-11 min) than with LR (75+/-10 min) (P < 0.001). In healthy humans, an infusion of large volumes of LR, but not NS, transiently decreased serum osmolality, whereas acidosis associated with NS persisted and urinary output was slower with NS. ⋯ Large volumes of lactated Ringer's solution administered to healthy humans produced small transient changes in serum osmolality. Large volumes of sodium chloride did not change osmolality but resulted in lower pH.
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Anesthesia and analgesia · May 1999
Randomized Controlled Trial Multicenter Study Clinical TrialHextend, a physiologically balanced plasma expander for large volume use in major surgery: a randomized phase III clinical trial. Hextend Study Group.
Hextend (BioTime, Inc., Berkeley, CA) is a new plasma volume expander containing 6% hetastarch, balanced electrolytes, a lactate buffer, and physiological levels of glucose. In preclinical studies, its use in shock models was associated with an improvement in outcome compared with alternatives, such as albumin or 6% hetastarch in saline. In a prospective, randomized, two-center study (n = 120), we compared the efficacy and safety of Hextend versus 6% hetastarch in saline (HES) for the treatment of hypovolemia during major surgery. Patients at one center had a blood sample drawn at the beginning and the end of surgery for thromboelastographic (TEG) analysis. Hextend was as effective as HES for the treatment of hypovolemia. Patients received an average of 1596 mL of Hextend: 42% received >20 mL/kg up to a total of 5000 mL. No patient received albumin. Hextend-treated patients required less intraoperative calcium (4 vs 220 mg; P < 0.05). In a subset analysis of patients receiving red blood cell transfusions (n = 56; 47%), Hextend-treated patients had a lower mean estimated blood loss (956 mL less; P = 0.02) and were less likely to receive calcium supplementation (P = 0.04). Patients receiving HES demonstrated significant prolongation of time to onset of clot formation (based on TEG) not seen in the Hextend patients (P < 0.05). No Hextend patient experienced a related serious adverse event, and there was no difference in the total number of adverse events between the two groups. The results of this study demonstrate that Hextend, with its novel buffered, balanced electrolyte formulation, is as effective as 6% hetastarch in saline for the treatment of hypovolemia and may be a safe alternative even when used in volumes up to 5 L. ⋯ Hextend (BioTime, Inc., Berkeley, CA) is a new plasma volume expander containing 6% hetastarch, balanced electrolytes, a lactate buffer, and a physiological level of glucose. It is as effective as 6% hetastarch in saline for the treatment of hypovolemia but has a more favorable side effects profile in volumes of up to 5 L compared with 6% hetastarch in saline.
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Anesthesia and analgesia · May 1999
Randomized Controlled Trial Clinical TrialClonidine administered as an axillary block does not affect postoperative pain when given as the sole analgesic.
Used as the sole analgesic, clonidine produces analgesia after epidural, intrathecal, and intraarticular administration. We conducted this double-blinded study to determine whether clonidine has analgesic effects when administered into the brachial plexus sheath. At the conclusion of hand or forearm surgery, performed under axillary brachial plexus block, 45 patients were randomly divided into three groups of 15 each to receive, through an axillary catheter, 15 mL of saline (Group Saline), clonidine 150 microg in 15 mL of saline (Group Clonidine), or bupivacaine 15 mL (Group Bupivacaine). The analgesic effects of the three solutions were evaluated for 6 h. Times to onset of pain and to first analgesic request were longer, and the total dose of pain medication was smaller in Group Bupivacaine compared with the other groups. Visual analog scores were significantly lower in Group Bupivacaine. There was no significant difference in time to onset of pain, time to first analgesic request, total dose of pain medication, and visual analog scores between Group Saline and Group Clonidine at any time. We conclude that the administration of clonidine 150 microg into the brachial plexus sheath does not prolong the onset of postoperative pain. ⋯ Used as the sole analgesic, clonidine produces analgesia after epidural, intrathecal, and intraarticular administration. It also prolongs the analgesic effect of brachial plexus block when mixed with local anesthetics. In this study, the administration of clonidine 150 microg alone into the brachial plexus sheath did not produce postoperative analgesia.