Acute recurrent bradycardia with evoked potential loss during transforaminal lumbar interbody fusion.

During a transforaminal lumbar interbody fusion a patient experienced acute intermittent bradycardia with manipulation of the intervertebral body space, followed by loss of somatosensory evoked potentials that did not recover. Postoperative evaluation revealed new bilateral lower extremity sensory and motor deficits. We postulate an afferent reflex arc to explain this and other reported instances of bradycardia and asystole during transforaminal lumbar interbody fusion surgery. Awareness of the association between bradycardia during lumbar spine surgery may alert anaesthetists, surgeons and neuromonitoring teams to impending neurological harm.

Prolonging viability of swine muscle biopsy specimens in malignant hyperthermia testing.

In North America, the caffeine halothane contracture test (CHCT) is the standard test for the diagnosis of malignant hyperthermia (MH). Current CHCT protocol recommends that the test be completed within 5 h of muscle excision. The purpose of this study was to investigate whether the period of skeletal muscle viability could be extended to 24 h. We tested the gracilis muscle from normal (n = 8) and MH-susceptible swine (n = 8). After baseline (1-2 h after excision) CHCT, the remaining muscles were placed into one of the following four treatment groups. In Groups 1 and 2, the muscles remained under tension and were stored in Krebs buffer (pH 7.4) at 23 degrees C-25 degrees C (clamped-warm) and 4 degrees C (clamped-cold), respectively. In Groups 3 and 4, the muscle strips were dissected, and the ends were tied with silk sutures, cut from the clamp, and placed in Krebs buffer at 23 degrees C-25 degrees C (free-warm) and 4 degrees C (free-cold), respectively. The responses of the treatment groups to halothane (3%) and caffeine (0.5-32 mM) were tested 22-26 h after excision. The clamped-warm storage was the only storage method to correctly diagnose MH susceptibility in all muscle strips tested. This finding was also confirmed in muscle stored under clamped-warm conditions and shipped overnight to another testing center for a parallel CHCT.

Pyruvate improves cerebral metabolism during hemorrhagic shock.

Pyruvate (PYR) improves cellular and organ function hypoxia and ischemia by stabilizing the reduced nicotinamide adenine dinucleotide redox state and cytosolic ATP phosphorylation potential. In this in vivo study, we evaluated the effects of intravenous pyruvate on neocortical function, indexes of the cytosolic redox state, cellular energy state, and ischemia during a prolonged (4 h) controlled arterial hemorrhage (40 mmHg) in swine. Thirty minutes after the onset of hemorrhagic shock, sodium PYR (n = 8) was infused (0.5 g x kg(-1) x h(-1)) to attain arterial levels of 5 mM. The volume and osmotic effects were matched with 10% NaCl [hypertonic saline (HTS)] (n = 8) or 0.9% NaCl [normal saline (NS)] (n = 8). During the hemorrhage protocol, the time to peak hemorrhage volume was significantly delayed in the PYR group compared with the HTS and NS groups (94 +/- 5 vs. 73 +/- 6 and 72 +/- 4 min, P < 0.05). In addition to the early onset of the decompensatory phase of hemorrhagic shock, the complete return of the hemorrhage volume during decompensatory shock resulted in the death of five and four animals, respectively, in the HTS and NS groups. In contrast, in the PYR group, reinfusion of the hemorrhage volume was slower and all animals survived the 4-h hemorrhage protocol. During hemorrhage, the PYR group also exhibited improved cerebral cortical metabolic and function status. PYR slowed and reduced the rise in neocortical microdialysis levels of adenosine, inosine, and hypoxanthine and delayed the loss of cerebral cortical biopsy ATP and phosphocreatine content. This improvement in energetic status was evident in the improved preservation of the electrocorticogram in the PYR group. PYR also prevented the eightfold increase in the excitotoxic amino acid glutamate observed in the HTS group. The findings show that PYR administered after the onset of hemorrhagic shock markedly improves cerebral metabolic and functional status for at least 4 h.

Ascorbate reduces superoxide production and improves mitochondrial respiratory chain function in human fibroblasts with electron transport chain deficiencies.

The present paper attempts to ascertain the role of ascorbate on the generation of superoxide radicals in skin fibroblasts of patients with deficiency of mitochondrial respiratory chain enzymes. Fibroblast cell lines were grown with or without ascorbate for the last 48 h of their growth period. The amount of superoxide radical production in cells was measured by the reduction of nitroblue tetrazolium and the activities of respiratory chain enzymes were examined in isolated fibroblast mitochondria. The results indicated a significant inverse correlation between the amount of superoxide radicals and the specific activities of complexes I-III and II-III of the respiratory chain. The ascorbate treatment of fibroblasts from control subjects did not show any effect on either superoxide radical production or respiratory chain enzymes' activities. While in patient's fibroblasts, this vitamin significantly decreased the superoxide radicals and increased the specific activities of I-III and II-III complexes but not complex IV. These observations indicate that superoxide radicals are increased in patients with deficient respiratory chain enzymes in their fibroblasts and ascorbate can prevent the loss of these enzymes by acting on the selected sites in the respiratory chain, which are related to the production of free radicals.

Monitoring of somatosensory and motor evoked potentials during open reduction and internal fixation of pelvis and acetabular fractures.

Monitoring of motor and somatosensory evoked potentials provides instantaneous intraoperative assessment of a patient's neurologic status. Monitoring of the sciatic nerve through motor and somatosensory evoked potentials can be used during open reduction and internal fixation of pelvic and acetabular fractures. A review of 12 pelvic and acetabular fractures treated with open reduction and internal fixation was conducted and assessed with a combination of intraoperative motor and somatosensory evoked potential monitoring. Results revealed intraoperative motor evoked potential monitoring was 100% sensitive and 100% specific in predicting postoperative sciatic nerve deficits, whereas somatosensory evoked potentials were not accurate in predicting postoperative sciatic nerve deficits. Combined monitoring of the sciatic nerve with motor and somatosensory evoked potentials is beneficial at predicting postoperative sciatic nerve deficits during open reduction and internal fixation of pelvic and acetabular fractures.

Induced hypothermia during emergency department thoracotomy: an animal model.

BACKGROUND: Induced hypothermia is used clinically to prevent ischemic injury during elective procedures. We present an animal model of asanguinous hypothermic (10 degrees C) circulatory arrest, induced through a left anterior lateral thoracotomy after exsanguinating uncontrolled hemorrhage. METHODS: Through a left anterior thoracotomy, 26 swine (45-70 kg) sustained a laceration of the descending thoracic aorta, producing exsanguinating uncontrolled hemorrhage. After 5 minutes of severe hypotension (systolic BP <20 mm Hg), a 22 French Foley catheter was directed cephalad through the enlarged aortic wound. A solution (containing 42.5 mmol/L K+ and precooled to 1 degrees C) was infused to arrest/preserve the heart and brain. A second 24 French Foley catheter was then directed caudally through the same wound. The right atrium was opened to drain the venous system. The animal was cooled with a cardiopulmonary bypass pump (>5L/min) through the Foley catheters. Once 10 degree C was reached, a cannula was placed to the aortic root and the aortic laceration repaired. The animal was maintained at 10 degree C for a total of 90 minutes. Before the rewarming process, the circulation was rinsed with a solution containing normal levels of electrolytes followed by infusion of whole blood. Rewarming was performed by maintaining a 10-degree gradient on the heat exchanger. The first 16 animals were used in nonsurvival experiments to develop the technique and to record dural temperatures and electroencephalogram tracings. The last 10 animals were used to determine long-term survival and neurologic outcome. Group I: seven animals were kept at < 10 degrees C with flows less than 2L/min. Group II: three animals underwent 20, 30, and 40 minutes of no flow once they were cooled to 10 degrees C. After 6 weeks of survival and neurologic examinations, the brains were fixed for histologic evaluations. RESULTS: The average time to cool the head to 18 degrees C and 10 degrees C was 6 minutes and 12 minutes, respectively. The hematocrit fell below 2% by the end of the cooling period. A total of 7 of the 10 animals from the long-term study survived. Group I: five of seven animals survived. Four of the survivors had no appreciable neurologic deficits, were fully functional at 6 weeks, and had no evidence of histologic injury. One of the five survivors in this group had moderate neurologic disability. Of the two animals that died, one died from air embolism from the i.v. line. The second death was in an animal for which maximal cooling to 2.7 degrees C was attempted. Group II: The first two animals that had "no flow" for 20 and 30 minutes were fully functional and had normal neurologic examinations. However, the second animal was found to have brain injury on histologic examination. The last animal in this group died of accidental extubation during recovery. CONCLUSION: Induction of hypothermic arrest through the chest after exsanguination is possible. The further development of this technique may provide an extended state of "suspended animation" to allow for repairs of hemorrhaging injuries in trauma patients who require emergency department thoracotomy.

Intravenous pyruvate prolongs survival during hemorrhagic shock in swine.

Pyruvate improves cellular and organ function during hypoxia and ischemia and stabilizes the NADH redox state and cytosolic ATP phosphorylation potential. In this in vivo study, we evaluated the effects of intravenous pyruvate on cardiovascular and neocortical function, indexes of the cytosolic redox state (lactate/pyruvate ratio, L/P) and cellular energy state (adenosine and degradative products hypoxanthine and inosine, ADO + HX + Ino) during controlled arterial hemorrhage (40 mmHg) in sedated swine (45 kg). Na+ pyruvate was infused 1 h before (1 g. kg(-1). h(-1)) and 2 h during (0.5 g. kg(-1). h(-1)) hemorrhage to attain arterial pyruvate levels of 6 mM. Volume (0.9% NaCl) and osmotic (10% NaCl) effects were matched in controls. Time to peak hemorrhage (57 min) and peak hemorrhage volume (43 ml/kg) were similar in all groups. The volume and osmotic groups experienced spontaneous cardiovascular decompensation between 60 and 90 min, with an average time until death of 82.7 +/- 5.5 and 74.8 +/- 8.2 min. In contrast, survival in the pyruvate group was 151.2 +/- 10.0 min (P < 0.001). During hemorrhage, the pyruvate group had better cardiovascular and cerebrovascular function with significantly higher systemic and cerebral oxygen consumption and less attenuation of the amplitude and frequency of the electrocorticogram. In addition, pyruvate prevented metabolic acidosis and stabilized the L/P. Pyruvate slowed the rise in neocortical microdialysis levels of ADO + HX + Ino, and prevented the net efflux of ADO + HX + Ino into the sagittal sinus. The findings reveal considerable metabolic and functional enhancement by pyruvate during severe hemorrhagic shock with a 75-min delay in spontaneous cardiovascular decompensation and death.

Inhaled nitric oxide attenuates increased pulmonary artery pressure following diaspirin crosslinked hemoglobin (DCLHB) administration.

Intravenous administration of diaspirin crosslinked hemoglobin (DCLHb) can result in elevated pulmonary and systemic arterial pressures in some mammalian species. This study was designed to evaluate the ability of inhaled nitric oxide (INO) to attenuate elevations in pulmonary artery pressure in a closed-chested swine model. Yorkshire pigs received escalating doses of INO followed by escalating doses of DCLHb or a single dose of DCLHb followed by escalating doses of INO. Systemic and pulmonary arterial pressures were monitored continuously. Significant elevations occurred in systemic and pulmonary arterial pressure following a cumulative dose of 0.1 gm/kg DCLHb. A single dose of 0.3 gm/kg also resulted in elevations of pulmonary and systemic arterial pressure. Inhaled nitric oxide partially reversed the changes in pulmonary but not systemic pressure. These results indicate that INO might be a therapeutic option for humans who may experience increased pulmonary artery pressure following administration of DCLHb.

Hemodynamic changes induced by liposomes and liposome-encapsulated hemoglobin in pigs: a model for pseudoallergic cardiopulmonary reactions to liposomes. Role of complement and inhibition by soluble CR1 and anti-C5a antibody.

BACKGROUND: Intravenous administration of some liposomal drugs can trigger immediate hypersensitivity reactions that include symptoms of cardiopulmonary distress. The mechanism underlying the cardiovascular changes has not been clarified. METHODS AND RESULTS: Anesthetized pigs (n=18) were injected intravenously with 5-mg boluses of large multilamellar liposomes, and the ensuing hemodynamic, hematologic, and laboratory changes were recorded. The significant (P<0.01) alterations included 79+/-9% (mean+/-SEM) rise in pulmonary arterial pressure, 30+/-7% decline in cardiac output, 11+/-2% increase in heart rate, 236+/-54% increase in pulmonary vascular resistance, 71+/-27% increase in systemic vascular resistance, and up to a 100-fold increase in plasma thromboxane B2. These changes peaked between 1 and 5 minutes after injection, subsided within 10 to 20 minutes, were lipid dose-dependent (ED50=4. 5+/-1.4 mg), and were quantitatively reproducible in the same animal several times over 7 hours. The liposome-induced rises of pulmonary arterial pressure showed close quantitative and temporal correlation with elevations of plasma thromboxane B2 and were inhibited by an anti-C5a monoclonal antibody (GS1), by sCR1, or by indomethacin. Liposomes caused C5a production in pig serum in vitro through classic pathway activation and bound IgG and IgM natural antibodies. Zymosan- and hemoglobin-containing liposomes and empty liposomes caused essentially identical pulmonary changes. CONCLUSIONS: The intense, nontachyphylactic, highly reproducible, complement-mediated pulmonary hypertensive effect of minute amounts of intravenous liposomes in pigs represents a unique, unexplored phenomenon in circulation physiology. The model provides highly sensitive detection and study of cardiopulmonary side effects of liposomal drugs and many other pharmaceutical products due to "complement activation-related pseudoallergy" (CARPA).

The anesthetic and physiologic effects of an intravenous administration of a halothane lipid emulsion (5% vol/vol)

UNLABELLED: The i.v. administration of < or = 9 mL of nonvaporized liquid halothane causes significant pulmonary damage, cardiovascular decompensation, and death. To determine whether liquid halothane mixed in a lipid emulsion would alter these toxic effects, six swine were evaluated in a randomized cross-over study. The pulmonary, analgesic, hemodynamic, and histopathologic effects of liquid halothane (25 mL) mixed with a liquid carrier (475 mL, Liposyn III 20%) and administered by constant infusion were compared with halothane administered by a calibrated vaporizer. Three swine received the halothane lipid emulsion (HLE), followed by inhaled halothane. Three additional swine received inhaled halothane, followed by the HLE. There were no changes in pulmonary compliance or arterial blood gases during or after the administration of equivalent volumes of halothane (13.75 mL) either by infusion of HLE or by inhalation of halothane. The end-tidal halothane concentration for the minimum alveolar anesthetic concentration was 0.79% +/- 0.08% during HLE administration and 1.13% +/- 0.12% for inhaled halothane (P < 0.001). Hemodynamic variables and blood halothane levels by gas chromatography were measured at end-tidal concentrations of 0.6%, 1.2%, and 1.8%. Blood halothane levels (mg/mL) were significantly higher (P < 0.05) after the administration of HLE at end-tidal halothane concentrations of 1.2% (0.49 +/- 0.19 vs 0.82 +/- 0.18) and 1.8% (0.79 +/- 0.17 vs 1.29 +/- 0.34). When compared at equivalent blood levels, HLE caused fewer changes in the left ventricular end-diastolic pressure, mean arterial pressure, and dP/dt than inhaled halothane. There was no evidence of pulmonary histopathologic damage 4-8 h after the infusion of 500-700 mL of HLE. This novel method of delivery of a volatile anesthetic seems to lack the toxicity of direct i.v. administration of liquid halothane. It may be a useful alternative to traditional administration via a vaporizer. IMPLICATIONS: Halothane causes pulmonary dysfunction and death when given i.v. in liquid form. Six swine received a halothane lipid emulsion i.v. to evaluate the anesthetic and physiologic effects. No pulmonary toxicity or deaths were associated with the halothane lipid emulsion. The anesthetic profile was similar to delivery of halothane via a vaporizer.

Tranexamic acid and aprotinin reduce postoperative bleeding and transfusions during primary coronary revascularization.

UNLABELLED: We evaluated the blood conservation effects of tranexamic acid (TA) or aprotinin administered before and during cardiopulmonary bypass (CPB) in a prospective, randomized, double-blind study of 150 adult patients undergoing primary coronary artery bypass grafting surgery. Patients received either TA (2 g) or large-dose aprotinin (7 million KIU). Thirty additional untreated patients otherwise managed in a similar fashion were included from a recently completed study for comparison of outcomes. Demographic, medical, surgical, laboratory, mediastinal chest tube drainage (MCTD), transfusion, and outcome data were collected. Allogeneic blood product administration was tightly controlled. The demographic, medical, and surgical characteristics did not significantly differ between the two therapy groups. The median postoperative MCTD loss in the TA group did not significantly differ from that in the aprotinin-treated group (708 vs 600 mL). The percentage of patients that received no allogeneic blood products was 25% for the TA group and 27% for the aprotinin group (P = not significant). The median number of allogeneic blood products administered to the TA group (0 U) did not significantly differ from that administered to the aprotinin group (0 U). The percentage of patients with excessive MCTD (>1000 mL/24 h) did not significantly differ between groups (19% and 17%, respectively). In comparison, the control group had a significantly greater (P < 0.05) median MCTD (1020 mL), median allogeneic blood product exposure (4.5 U), and incidence of excessive MCTD (66%) and transfusion therapy (66%). These data help to support the use of pharmacologic methods to improve clinically relevant indicators of blood conservation for primary CPB procedures. Furthermore, the data show that TA is equivalent to aprotinin for blood conservation in patients at risk of excessive post-CPB bleeding and transfusion therapy. IMPLICATIONS: In a randomized, blind trial, we evaluated the effects of tranexamic acid or aprotinin on blood conservation after primary cardiopulmonary bypass surgery. Both drugs were equally effective in reducing blood loss, the incidence of transfusion, and the amount of blood products transfused compared with placebon.

Validating the concept of abuse: women's perceptions of defining behaviors and the effects of emotional abuse on health indicators.

OBJECTIVES: To validate the construct of abuse in 2 ways: first, to examine female patients' perceptions of abusive behaviors that are typically used in standardized abuse scales; and second, to determine health status symptom and medical utilization differences between women who report emotional abuse and women who are not abused. DESIGN: Cross-sectional interviews and medical record reviews. MAIN OUTCOME MEASURES: Modified directions to the Conflict Tactics Scale were used to identify women's perceptions of abusive behaviors. Personal history of abuse was determined by self-report. Health status was measured using the Medical Outcomes Study Short-Form Health Survey-36 and medical services utilization was determined from medical records. The Wahler Physical Symptom Inventory was used to measure symptom experience. SETTING: Patients were interviewed in either a rural primary care practice or an urban medical university practice. PATIENTS: Four hundred seven women older than 18 years were interviewed. Half were from an urban and half from a rural setting. Sixty-four percent of the sample was black. RESULTS: Women saw more behaviors as abusive than are typically identified by the Conflict Tactics Scale and abused women identified more abusive behaviors than nonabused women. Significant health status differences were found between women who reported emotional abuse with no concurrent physical or sexual abuse and nonabused women on 7 of the 8 dimensions of the Short-Form Health Survey health status scales and on 25% of measured symptoms. CONCLUSIONS: These findings reflect the idea that women consider many behaviors to be abusive and that abused women perceive more behaviors as abusive than do nonabused women. Given that significant health status differences are shown between emotionally abused and nonabused women, emotional abuse can be viewed as a critical variable in patient health behavior.

Tranexamic acid is effective in decreasing postoperative bleeding and transfusions in primary coronary artery bypass operations: a double-blind, randomized, placebo-controlled trial.

UNLABELLED: We evaluated the effects of tranexamic acid (TA) administered before and after cardiopulmonary bypass (CPB) in a prospective, randomized, placebo-controlled, double-blind study of adult patients undergoing primary coronary artery bypass grafting surgery. Patients received placebo (n = 30) or TA 15 mg/kg before CPB, followed by a TA infusion of 1 mg x kg(-1) x h(-1) for 5 h (n = 30) or TA 15 mg/kg after CPB, followed by a TA infusion of 1 mg x kg(-1) x h(-1) for 5 h (n = 30). Demographic, medical, surgical, laboratory, mediastinal chest tube drainage (MCTD), hemoglobin loss, transfusion, and outcome data were collected. Allogenic blood product administration was tightly controlled. The demographic, medical, and surgical characteristics were similar in all three groups. The median postoperative MCTD and hemoglobin loss in the pre-CPB TA group (710 mL, 8.6 g) was significantly less (P < 0.001) compared with the control (1202 mL, 44.2 g) and post-CPB TA groups (1020 mL, 23.4 g). The percentage of patients who received no allogenic blood products was 27% for the pre-CPB TA group and 33% for the post-CPB TA group (not significant). These percentages were significantly lower than those in the placebo group (66%, P < 0.001). The median number of allogenic blood products administered to the pre-CPB TA group (0 units) was significantly less compared with the control group (4.5 units). The thromboelastogram and fibrinogen split product levels in the pre-CPB TA group indicated better platelet function and less activation of the fibrinolytic system compared with the other two groups (P < 0.05). There were no intergroup differences in reoperation, myocardial infarction, stroke, infections, or death. These data support the use of pre-CPB TA to decrease patient exposure to postcardiopulmonary bypass allogenic blood products. IMPLICATIONS: In this randomized, placebo-controlled trial, we investigated the efficacy of tranexamic acid to decrease bleeding and blood transfusions after open-heart operations. Tranexamic acid administered before and during the operation was effective in decreasing both bleeding and transfusions. When tranexamic acid was administered immediately after the operation, it had a minor beneficial effect.

Profound normovolemic hemodilution: hemostatic effects in patients and in a porcine model.

Previous systematic investigations of the hemostatic effects of normovolemic hemodilution (NHD) have not explored the influence of hematocrits less than 20% in humans or animals. However, clinical interest in maximizing the perioperative conservation of erythrocytes may involve profound NHD beyond traditionally accepted empiric end points. We report here on coagulation data in eight healthy adolescent patients undergoing profound NHD in concert with surgical correction of idiopathic scoliosis, and in 29 swine undergoing experimental stepwise NHD until death. Blood was replaced with 5% albumin in 0.9% saline in our patients, and with 5% albumin in lactated Ringer's solution in our pigs. A 75% blood volume exchange in our patients yielded a platelet count (PLT) of 158 +/- 26 x 10(3)/microL, fibrinogen concentration (FIB), 50 +/- 7 mg/dL, prothrombin time (PT), 25.4 +/- 2.6 s, activated partial thromboplastin time (aPTT), 87 +/- 15s, and a nadir hemoglobin of 2.8 +/- 0.2 g/dL; however, global oxygen delivery as assessed by body oxygen consumption remained adequate. Coagulation during the experimental porcine hemodilution was assessed by measuring PLT, FIB, PT, and aPTT, as well as by measurement of coagulation factor activities. In neither species did clinically significant thrombocytopenia (PLT < 100 x 10(3)/ microL) become manifest prior to clinical or other laboratory evidence of coagulopathy. Rather, a combined deficiency of coagulation factors explains the coagulopathy developing during NHD in both patients and swine. Abnormal hemostasis develops prior to compromise of global tissue oxygenation, assessed by mixed venous oxygen saturation and total body oxygen consumption, during NHD in healthy patients anesthetized as described. Therefore, NHD may be more limited by preservation of normal coagulation than of global oxygen delivery and consumption.

Intravenous ketorolac tromethamine worsens platelet function during knee arthroscopy under spinal anesthesia.

Ketorolac prolongs bleeding time and inhibits platelet aggregation and platelet thromboxane production in healthy, awake volunteers. However, platelet function was recently shown not to worsen after ketorolac was given during general anesthesia. The purpose of this study was to investigate platelet function changes during a standardized spinal anesthetic and surgery, as well as after a single intraoperative dose of intravenous (IV) ketorolac. The study comprised 30 ASA physical status I patients undergoing spinal anesthesia for knee arthroscopy. Subjects were randomized to receive either ketorolac 60 mg IV 15 min after skin incision or placebo IV. Platelet function testing consisted of an Ivy bleeding time, platelet aggregometry with adenosine diphosphate (ADP) and collagen, thromboelastography (TEG), and serum thromboxane B2 (TxB2) assays. Platelet function testing was performed: 1) 15 min prior to the performance of spinal anesthesia; 2) 10 min after surgical skin incision; and 3) 45 min after administration of study drug. The placebo group demonstrated no changes in any platelet function variable during spinal anesthesia and surgery relative to preoperative values. The ketorolac group, however, demonstrated a significant increase in bleeding time from postincision to poststudy drug data points (213 +/- 60s to 275 +/- 85s, mean +/- SD; P < 0.01). Further, platelet aggregometry to collagen was diminished in the ketorolac group from preoperative to poststudy drug data points (90.8% +/- 7.6% to 60.5% +/- 32.5%; P < 0.01). Platelet aggregometry with ADP, however, was unchanged in the ketorolac group. Platelet TxB2 production decreased dramatically in the ketorolac group from preoperative to poststudy drug data points (157.2 +/- 129.4 to 0.3 +/- 0.3 ng/mL; P < 0.01). Platelet function does not appear to be accentuated during spinal anesthesia as it is during general anesthesia. Unlike during general anesthesia, platelet function during spinal anesthesia is impaired, with respect to bleeding time and platelet aggregometry to collagen, by a single intraoperative dose of IV ketorolac.

Evaluation of a double-lumen multiorifice catheter for resuscitation of swine from lethal venous air embolism.

BACKGROUND: A double-lumen multiorifice catheter has been developed to potentially enhance accurate electrocardiographic central venous localization and resuscitation from a massive venous air embolism (VAE). This double-lumen multiorifice catheter was compared to a Bunegin-Albin multiorifice catheter for flow characteristics, air aspiration efficiency, and efficacy in resuscitating swine from a lethal VAE. METHODS: Flow characteristics of both catheters were determined by aspirating both agitated and unagitated citrated swine blood with a 50-ml syringe. Swine were anesthetized with halothane and positioned to approximate a modified sitting craniotomy position (45-degree elevation). By a random block method, 24 swine were assigned to either catheter (n = 12 each catheter) for the initial air aspiration. Catheters were positioned, using intravenous electrocardiography, with the distal aspiration orifice in the high right atrium. A 5-ml/kg air embolism was administered over 30 s into the sagittal sinus, and the swine were resuscitated by aspirating air through the multiorifice catheters and then positioning the swine horizontally. Surviving animals were allowed to recover for 60 min. The initial catheter was exchanged and repositioned in the high right atrium using intravenous electrocardiography. A 5-ml/kg air embolus was administered, and the swine were resuscitated as in the first challenge. Surviving swine recovered for 60 min, repositioned, and administered a third 5-ml/kg air embolism. On this final challenge, no attempt was made to resuscitate the animal by aspirating the multiorifice catheter. RESULTS: Flow characteristics of both catheters were similar in the unagitated blood (195.3 +/- 1.9 vs. 196.7 +/- 2.5 ml/min). The flow rate of agitated blood through the double-lumen multiorifice catheter was 14% greater than through the Bunegin-Albin catheter (136.3 +/- 6.8 vs. 117 +/- 5.9 ml/min, P = 0.001). Forty-three air embolism trials were conducted at 5 ml/kg. All nine trials at 5 ml/kg without air aspiration resulted in death. Five animals died during the embolism dose determination trials, and four died during the third embolism challenge. The use of a multiorifice catheter for aspiration after a VAE enhanced survival after a 5-ml/kg sagittal sinus air embolus (14/34 vs. 0/9, P = 0.02). Although the double-lumen multiorifice catheter was more efficient than the Bunegin-Albin catheter in percentage of air retrieved (37.7 +/- 12.0 vs. 29.7 +/- 10.1, P = 0.042). Aspiration of the VAE with the double-lumen multiorifice catheter successfully rescued 9 of the 15 trials, and aspiration using the Bunegin-Albin catheter resuscitated 5 of the 19 (P = 0.08). CONCLUSIONS: Multiorifice catheters are effective in resuscitating swine from a lethal VAE. The double-lumen multiorifice catheter evaluated aspirated a larger percentage of the VAE but was not statistically more effective than the Bunegin-Albin catheter in resuscitating the animals. Based on these findings of improved flow rate and efficiency in air aspiration, further investigation of this double-lumen multiorifice catheter is warranted.

Experience of abuse in primary care patients. Racial and rural differences.

OBJECTIVE: To examine the experience of abuse in rural, urban, black, and white women on the following dimensions: prevalence, symptom experience, health status, medical services utilization, and coping mechanisms. DESIGN: Retrospective study using patient interviews. SETTING: Half the subjects were recruited from a large medical university family medicine center and half from a rural family medicine center, both in the Southeast. PATIENTS: Four hundred seven women were interviewed. Groups were distributed as follows: urban white, 24.9% (n = 99); urban black, 25.6% (n = 102); rural white, 11.1% (n = 44); and rural black, 38.4% (n = 153). MAIN OUTCOME MEASURES: Self-report of abuse (sexual, physical, and emotional) was related to symptom history, current health status, medical services utilization, and coping styles. RESULTS: Sixty-six percent of the total sample reported some kind of abuse. Black, rural women reported the least (52.3%). Presence of greater numbers of symptoms, greater medical services utilization, and lower health status were found in the abused population. Abused women used all types of coping mechanisms to a greater extent than non-abused women. Black women were more likely to use confrontation (F = 8.82 [P = .003]), problem solving (F = 8.24 [P = .004]), and reappraisal (F = 4.13 [P = .04]) than white women. Rural women were more likely to use psychological distancing (F = 5.25 [P = .02]) and escape (F = 5.67 [P = .02]) than urban women, although abused women in general use those coping methods more than nonabused women. CONCLUSIONS: The experience of abuse remains similar across black, white, rural, and urban women; however, coping mechanisms appear to be influenced by group membership.

Intravenous ketorolac tromethamine does not worsen platelet function during knee arthroscopy under general anesthesia.

Ketorolac (KT) prolongs bleeding time and inhibits platelet aggregation and platelet thromboxane production in healthy, awake volunteers. However, platelet function may be accentuated during the stress of general anesthesia (GA) and surgery. The purpose of this study was to investigate platelet function changes during a standard GA technique and surgery, as well as after a single intraoperative dose of intravenous (i.v.) KT. The study comprised 30 ASA physical status I patients undergoing GA for knee arthroscopy. Subjects were randomized to receive either KT 60 mg IV 15 min after skin incision or placebo i.v. Platelet function testing consisted of an Ivy bleeding time (BT), platelet aggregometry (PA) with adenosine diphosphate (ADP) and collagen, thromboelastography (TEG), and serum thromboxane B2 assays (TxB2). Platelet function testing was performed: 1) 15 min prior to the induction of GA, 2) 10 min after skin incision, and 3) 45 min after administration of study drug. BT decreased significantly in the placebo group from 263 +/- 133 s (mean +/- SD) preoperatively to 207 +/- 89 s postincision. BT did not change in the KT group. PA was unchanged after IV KT. TEG data was unchanged in both groups during anesthesia and surgery. TxB2 levels decreased markedly in the KT group from 106.9 +/- 96.2 ng/mL preoperatively to 0.4 +/- 1.2 ng/mL poststudy drug, P = 0.002. Platelet function appears to be accentuated during GA and surgery as evaluated by BT in the placebo group. Further, platelet function by BT, PA, and TEG was not inhibited after i.v. KT despite near complete abolition of TxB2 production.

Oxygen consumption and cardiovascular function in children during profound intraoperative normovolemic hemodilution.

The clinically acceptable limit of acute normovolemic, normothermic hemodilution, a standard procedure in scoliosis surgery, is not yet well defined. Eight ASA class I patients undergoing idiopathic scoliosis correction were administered a standard anesthetic with 100% oxygen and controlled ventilation. Hemodilution was accomplished by exchanging whole blood for 5% albumin in 0.9% saline. Blood gases, acid-base status, and circulatory variables were recorded prior to and after hemodilution, and every 30 min throughout surgery. The impact of hemodilution was judged by mixed venous oxygen saturation which was maintained at > or = 60%, while intravascular volume was maintained with the 5% albumin solution. Reinfusion of the autologous blood was completed by the end of surgery. In the eight controlled cases in which normovolemic hemodilution was studied, hemoglobin levels decreased from 10.0 +/- 1.6 g/dL to 3.0 +/- 0.8 g/dL. Mixed venous oxygen saturation decreased from 90.8% +/- 5.4% to 72.3% +/- 7.8%. Oxygen extraction ratio increased from 17.3% +/- 6.2% to 44.4% +/- 5.9%. Oxygen delivery decreased from 532.1 +/- 138.1 mL.min-1.m-2 to 260.2 +/- 57.1 mL.min-1.m-2, while global oxygen consumption did not decrease and plasma lactate did not appreciably increase. Central venous pressure increased and peripheral resistance decreased during hemodilution. Cardiac index increased, heart rate remained essentially constant, and left ventricular stroke work index did not decrease significantly. No patients suffered clinically adverse outcomes. Global oxygen transport and myocardial work can be maintained at extreme normovolemic anemia. Our evidence suggests that stages of normovolemic hemodilution more severe than previously reported may be clinically acceptable for young, healthy patients during normocarbic anesthesia.