Anesthesia and analgesia
-
Anesthesia and analgesia · May 1999
Small-dose inhaled nitric oxide attenuates hemodynamic changes after pulmonary air embolism in dogs.
Inhaled nitric oxide (NO) has been used to treat pulmonary hypertension. Experimental studies have suggested therapeutic effects of NO after pulmonary microembolism. We evaluated the protective effects of NO in dogs during a pulmonary air embolism (PAE). NO (3 ppm) was administered to six anesthetized mongrel dogs (NO group) but not to the seven dogs in the control group. After 20 min, each dog received a venous air injection of 2.5 mL/kg. Hemodynamic evaluation was performed, and blood samples were drawn for blood gas analysis before and after NO inhalation and 5-60 min after the PAE. Both arterial blood pressure and cardiac output were decreased in the control group for >15 min after PAE, whereas NO-treated animals showed only transient hypotension. NO attenuated the pulmonary hypertension after PAE, as demonstrated by small (P < 0.05) increases in pulmonary artery pressure and pulmonary vascular resistance index in NO-treated animals (90% and 135%, respectively) compared with the controls (196% and 282%, respectively). These hemodynamic effects of NO were associated with higher mixed venous O2 tensions and saturations in the NO group compared with the controls. We conclude that small-dose NO (3 ppm) attenuated the hemodynamic changes induced by PAE in dogs. This protective effect of NO on hemodynamics is not accompanied by improvement in pulmonary oxygenation in this setting. ⋯ In this study, we evaluated the protective effects of inhaled nitric oxide in a pulmonary air embolism setting. Nitric oxide attenuated the hemodynamic changes induced by pulmonary air embolism without improving pulmonary oxygenation.
-
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.
-
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.