Anesthesia and analgesia
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Several characteristics of sevoflurane biotransformation are apparent from the preceding investigations. Metabolism is rapid, with fluoride and HFIP appearing in plasma within minutes after the start of sevoflurane administration (38-40,51). Peak plasma fluoride concentrations generally occur within approximately 1 h after the termination of sevoflurane administration in most patients, regardless of the dose or duration of exposure (ranging from 0.35-9.5 MAC-h) (39,48). ⋯ Although both sevoflurane and methoxyflurane may produce plasma fluoride concentrations in excess of 50 microM, they have not produced the same nephrotoxic effects. Clearly, anesthetic metabolism and anesthetic toxicity can no longer be considered synonymous. The introduction of sevoflurane into clinical practice will hopefully stimulate new investigations into biochemical mechanisms of anesthetic toxicity and continued clinical investigations regarding the relationship between anesthetic metabolism and organ toxicity.
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Anesthesia and analgesia · Dec 1995
Comparative StudyA comparison of four bedside methods of hemoglobin assessment during cardiac surgery.
The purpose of this study was to compare the accuracy of conductivity, adjusted conductivity, photometric, and centrifugation methods of measuring or estimating hemoglobin (Hb) with Coulter measured HB as the reference. These bedside methods were studied in 25 cardiac surgery patients during euvolemia and hemodilution and after salvaged autologous red blood cell transfusion. In vivo patient blood samples were obtained before induction, at the start of cardiopulmonary bypass (CPB), after CPB, and after blood transfusion. ⋯ Hb assessment by different test methods may be significantly affected during hemodilution and after blood transfusion. In vitro conditions exaggerated the inaccuracy of conductivity and adjusted conductivity Hb estimates. The rank order of closest approximation to the Coulter measurement for all in vivo blood samples was provided by bedside photometry, followed by centrifugation, adjusted conductivity, and uncorrected conductivity methods.
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Anesthesia and analgesia · Dec 1995
Clinical Trial Controlled Clinical TrialTransient neurologic symptoms after spinal anesthesia.
We recently reported several cases consistent with transient radicular irritation after spinal anesthesia with hyperbaric 5% lidocaine. The present prospective, blind, nonrandomized study was performed to determine the incidence of these transient neurologic symptoms and to identify factors that might be associated with their occurrence. We studied 270 patients scheduled for gynecologic or obstetric procedures under spinal anesthesia. ⋯ Transient neurologic symptoms were observed in 37% of patients receiving 5% lidocaine, whereas only one patient receiving 0.5% bupivacaine had transient hypesthesia of the lateral aspect of the right foot. These results suggest that symptoms were the result of a specific drug effect. However, because of the limitations of the study one cannot conclude that lidocaine per se was the cause.
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Anesthesia and analgesia · Dec 1995
Comparative StudyLoss of alveolar macrophages during anesthesia and operation in humans.
Pulmonary macrophages play an important role in the host defense against infection, and the importance of this role is probably enhanced when the upper airway defenses are circumvented by endotracheal intubation. Studies in animals suggest that exposure to volatile anesthetics compromises the viability and function of alveolar macrophages. We studied the effect of surgery and anesthesia on the alveolar macrophages of 41 human subjects undergoing lower abdominal procedures of varying lengths during nitrous oxide-isoflurane anesthesia. ⋯ However, there was a strong correlation between loss of macrophages and the duration of surgery and anesthesia. Aggregation increased and viability decreased as a function of procedure length. Studies are needed to determine whether prolonged surgery contributes to the incidence of postoperative pulmonary complications by disturbing the function and survival of alveolar macrophages in humans.
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Anesthesia and analgesia · Dec 1995
Comparative StudyDoes hypercarbia develop faster during laparoscopic herniorrhaphy than during laparoscopic cholecystectomy? Assessment with continuous blood gas monitoring.
The use of CO2 to create and maintain a pneumoperitoneum during laparoscopic surgery may lead to hypercarbia and acidosis. CO2 is also insufflated into the preperitoneal space to create and maintain a pneumopreperitoneum for laparoscopic herniorrhaphy. This study examined the influence of CO2 pneumopreperitoneum on the development of hypercarbia and acidosis assessed with continuous intraarterial blood gas monitoring. ⋯ Pneumopreperitoneum resulted in a significantly faster development of hypercarbia (P = 0.023) and acidosis (P = 0.027) than pneumoperitoneum. These results were not explained when corrected for changes in hemodynamic and ventilatory variables using analysis of covariance. We conclude that the more rapid development of hypercarbia and acidosis during pneumopreperitoneum can be explained by increased CO2 absorption through an increasing gas exchange area during the procedure and through a larger wound bed.