Anesthesia and analgesia
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Anesthesia and analgesia · May 2002
Randomized Controlled Trial Clinical TrialThe absence of acute tolerance during remifentanil infusion in volunteers.
The development of acute opioid tolerance in humans remains controversial. We tested the hypothesis that continuous remifentanil infusion leads to rapid development of opioid tolerance. Twenty healthy male volunteers were enrolled onto a randomized, placebo-controlled, double-blinded, cross-over design study to receive a 3 h continuous infusion of remifentanil (0.08 microg x kg(-1) x min(-1)) or saline. Test procedures included determination of pain perception thresholds and pain tolerance thresholds to heat and cold and neuroselective sine wave constant current at 5 Hz and 250 Hz. Test procedures were performed at baseline and then repeated at 25, 55, 85, 115, and 160 min (heat/cold) and at 35, 65, 95, 125, and 170 min (electrical current) during infusion. No significant decrease of the pain threshold devolutions between 55 and 180 min after the start of infusion of remifentanil could be detected. In conclusion, no development of acute opioid tolerance was observed during constant remifentanil infusion of 3 h in volunteers. ⋯ The opioid remifentanil was applied to 20 volunteers at a constant concentration for 3 h while pain thresholds to temperature and current were repeatedly assessed. Our aim was to study whether thresholds decrease over time because of the rapid development of opioid tolerance. No development of rapid opioid tolerance was observed.
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Anesthesia and analgesia · May 2002
The use of and preferences for the transesophageal echocardiogram and pulmonary artery catheter among cardiovascular anesthesiologists.
The pulmonary artery catheter (PAC), although widely used in anesthesia for cardiac and vascular surgery, remains controversial. Use of transesophageal echocardiography (TEE) by cardiovascular anesthesiologists may be a substitute or a preference compared with the PAC, but this has been incompletely investigated. An anonymous, cross-sectional survey was mailed to anesthesiologists in Canada and the United States. Anesthesiologists described their use of the PAC and TEE during cardiac and vascular surgery, along with their demographic characteristics. Two hundred sixty-five (77%) of 345 anesthesiologists responded. All had the PAC available for use, and 56% had TEE available. Only 23 (11% overall) reported having undergone echocardiography training, half of whom had completed fellowships. Both the PAC and TEE were more often used in cardiac valvular surgery (P = 0.0001) than in aortocoronary bypass or abdominal vascular surgery. Among all anesthesiologists, the PAC remained the preferred monitor in either cardiac or vascular surgery (P = 0.0001), although many indicated a preference for neither monitor. Among anesthesiologists with echocardiography training, TEE was preferred (P = 0.0004). We found that TEE was accessible to more than half of the surveyed anesthesiologists in cardiovascular surgery, but relatively few of them had completed formal training in its use. Only those with completed formal TEE training indicated a significant preference for TEE use and also used it frequently. Given the continuing controversy about the appropriate application of the PAC, concern about the appropriate application of TEE is prudent. The PAC remains the more frequently used and preferred monitor among cardiovascular anesthesiologists. ⋯ A survey of anesthesiologists found that pulmonary artery catheter monitoring is currently more frequently used compared with transesophageal echocardiography during cardiac and vascular surgery.
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Anesthesia and analgesia · May 2002
The impact of morbid obesity, pneumoperitoneum, and posture on respiratory system mechanics and oxygenation during laparoscopy.
We studied the effect of morbid obesity, 20 mm Hg pneumoperitoneum, and body posture (30 degrees head down and 30 degrees head up) on respiratory system mechanics, oxygenation, and ventilation during laparoscopy. We hypothesized that insufflation of the abdomen with CO(2) during laparoscopy would produce more impairment of respiratory system mechanics and gas exchange in the morbidly obese than in patients of normal weight. The static respiratory system compliance and inspiratory resistance were computed by using a Servo Screen pulmonary monitor. A continuous blood gas monitor was used to monitor real-time PaCO(2) and PaO(2), and the ETCO(2) was recorded by mass spectrometry. Static compliance was 30% lower and inspiratory resistance 68% higher in morbidly obese supine anesthetized patients compared with normal-weight patients. Whereas body posture (head down and head up) did not induce additional large alterations in respiratory mechanics, pneumoperitoneum caused a significant decrease in static respiratory system compliance and an increase in inspiratory resistance. These changes in the mechanics of breathing were not associated with changes in the alveolar-to-arterial oxygen tension difference, which was larger in morbidly obese patients. Before pneumoperitoneum, morbidly obese patients had a larger ventilatory requirement than the normal-weight patients to maintain normocapnia (6.3 +/- 1.4 L/min versus 5.4 +/- 1.9 L/min, respectively; P = 0.02). During pneumoperitoneum, morbidly obese, supine, anesthetized patients had less efficient ventilation: a 100-mL increase of tidal volume reduced PaCO(2) on average by 5.3 mm Hg in normal-weight patients and by 3.6 mm Hg in morbidly obese patients (P = 0.02). In conclusion, respiratory mechanics during laparoscopy are affected by obesity and pneumoperitoneum but vary little with body position. The PaO(2) was adversely affected only by increased body weight. ⋯ Morbid obesity significantly decreases respiratory system compliance and increases inspiratory resistance. Increased body weight, and not altered mechanics of breathing, was associated with worse PaO(2) during laparoscopy.
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Anesthesia and analgesia · May 2002
Fibrinolysis during liver transplantation is enhanced by using solvent/detergent virus-inactivated plasma (ESDEP).
After the introduction of solvent/detergent-treated plasma (ESDEP) in our hospital, an increased incidence of hyperfibrinolysis was observed (75% vs 29%; P = 0.005) compared with the use of fresh frozen plasma for liver transplantation. To clarify this increased incidence, intraoperative plasma samples of patients treated with fresh frozen plasma or ESDEP were analyzed in a retrospective observational study. During the anhepatic phase, plasma levels of D-dimer (6.58 vs 1.53 microg/mL; P = 0.02) and fibrinogen degradation products (60 vs 23 mg/L; P = 0.018) were significantly higher in patients treated with ESDEP. After reperfusion, differences increased to 23.5 vs 4.7 microg/mL (D-dimer, P = 0.002) and 161 vs 57 mg/L (fibrinogen degradation products, P = 0.001). The amount of plasma received per packed red blood cell concentrate, clotting tests, and levels of individual clotting factors did not show significant differences between the groups. alpha(2)-Antiplasmin levels, however, were significantly lower in patients receiving ESDEP during the anhepatic phase (0.37 vs 0.65 IU/mL; P < 0.001) and after reperfusion (0.27 vs 0.58 IU/mL; P = 0.001). Analysis of alpha(2)-antiplasmin levels in ESDEP alone showed a reduction to 0.28 IU/mL (normal >0.95 IU/mL) because of the solvent/detergent process. Therapeutic consequences for the use of ESDEP in orthotopic liver transplantation are discussed in view of an increased incidence of hyperfibrinolysis caused by reduced levels of alpha(2)-antiplasmin in the solvent/detergent-treated plasma. ⋯ The use of solvent/detergent virus-inactivated plasma is of increasing importance in the prevention of human immunodeficiency virus and hepatitis C virus transmission. Since the use of this plasma during orthotopic liver transplantation has increased, the incidence of hyperfibrinolysis was observed. Clotting analysis of the patients revealed small alpha(2)-antiplasmin concentrations because of the solvent/detergent process.
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Anesthesia and analgesia · May 2002
Case ReportsMassive hemorrhage during radiofrequency ablation of a pulmonary neoplasm.
Radiofrequency ablation is a new investigational therapy for primary and secondary neoplasms. In this article, the authors describe the anesthetic management of the radiofrequency ablation of a pulmonary neoplasm complicated by massive hemorrhage.