Anesthesia and analgesia
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Anesthesia and analgesia · Oct 2002
Randomized Controlled Trial Clinical TrialThe influence of active warming on signal quality of pulse oximetry in prehospital trauma care.
Victims of trauma such as contusions and simple fractures are usually transported by paramedics. Because many victims are intoxicated with alcohol or other drugs, they are vulnerable to some risk of inadequate respiration. Thus, their oxygenation is monitored by noninvasive pulse oximetry. We tested the hypothesis that active warming of the whole body during transport to the hospital can improve the reliability of arterial oxygen saturation (SpO(2)) monitoring. Twenty-four trauma patients transported to hospital were included in the study and randomly assigned to two groups: one group (n = 12) was covered with normal wool blankets, and the other group (n = 12) was treated with resistive heating blankets during transport. We recorded core temperature, shivering, skin temperature at the forearm and finger, SpO(2), and hemodynamic variables. Before randomization, both groups were comparable. On arrival at the hospital, the actively warmed patients had significantly warmer core (36.1 +/- 0.3 degrees C versus 35.5 +/- 0.3 degrees C; P < 0.001) and skin (34.1 +/- 1.5 degrees C versus 24.9 +/- 1.4 degrees C; P < 0.001) temperatures. In the actively warmed group, the pulse oximeter had significantly fewer alerts (31 versus 58) and a significantly less time of malfunction (146 +/- 42 s versus 420 +/- 256 s) and provided more constant measurements in the actively warmed group (P < 0.001). In this study we showed that active warming improves pulse oximeter monitoring quality in trauma patients during transport to the hospital. ⋯ Clinical trials show that pulse oximeter signal quality is limited by hypothermia. In this study we show that active whole-body warming of trauma victims improves monitoring quality during transport to the hospital.
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Anesthesia and analgesia · Oct 2002
Comparative Study Clinical TrialA comparison between anterior and posterior monitoring of neuromuscular blockade at the diaphragm: both sites can be used interchangeably.
We present a novel site of monitoring neuromuscular blockade of the diaphragm at the patient's back. After the induction of anesthesia, 12 patients were orotracheally intubated. Two Ag/AgCl-electrodes were attached at the right seventh or eighth intercostal space between the midclavicular and anterior axillary line; two Ag/AgCl-electrodes were paravertebrally attached on the right side lateral to vertebrae T12-L1 or L1-2. Two Ag/AgCl-skin-electrodes were placed over the right thenar area for an electromyography recording of the adductor pollicis (AP) muscle, and two Ag/AgCl-skin-electrodes were used to stimulate the ulnar nerve. Onset and offset of neuromuscular blockade after rocuronium 0.6 mg/kg were determined, and significant differences between diaphragm and AP muscle and agreement between the two methods were determined. Mean maximum block was more than 96% at all sites. Lag time, onset 50, and onset time were not significantly different between the diaphragm and the AP. However, time to reach 25% of control twitch was significantly longer at the AP muscle than at the diaphragm (P < 0.001). The difference of the means and limits of agreement between the anterior and the posterior site of diaphragmatic monitoring were 0 +/- 11 s, 3 +/- 9 s, 0 +/- 19 s, and -2% +/- 5% for lag, onset 50, onset time, and peak effect, respectively, and -2 +/- 2 min for the time to reach 25% of control twitch of neuromuscular blockade. We conclude that anterior and posterior diaphragmatic monitoring can be used interchangeably to determine neuromuscular blockade after rocuronium. ⋯ We present a novel site of monitoring neuromuscular blockade of the diaphragm at the patient's back, which shows good agreement with the conventional anterior site at the seventh or eighth intercostal space.
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Anesthesia and analgesia · Oct 2002
Clinical TrialIn vitro fertilization-induced alterations in coagulation and fibrinolysis as measured by thromboelastography.
Supraphysiologic increases in estrogen produced by in vitro fertilization (IVF) promote the expression of hemostatic markers. Although quantitative studies of individual markers have been performed during IVF, their results are conflicting and do not reveal the qualitative effect of each marker on the overall coagulation and fibrinolytic processes. Thrombelastograph (TEG) coagulation analysis, by contrast, provides a global measure of coagulation and fibrinolysis and can indicate the relative contributions of clotting factors, fibrinogen, and platelets to each process. ⋯ Thrombelastograph coagulation analysis, which provides a global assessment of these changes, demonstrated significant alterations in two coagulation indices (clot formation time, coagulation index), although all variables remained within normal limits. The relative importance of fibrinogen versus platelets in determining clot strength was observed. No significant alterations in fibrinolysis were detected.
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Anesthesia and analgesia · Oct 2002
Flumazenil recovers diaphragm muscle dysfunction caused by midazolam in dogs.
We studied the effects of flumazenil on diaphragm muscle dysfunction caused by midazolam in dogs. Animals were divided into three groups of eight each. In each group, anesthetic doses (0.1 mg/kg initial dose plus 0.5 mg. kg(-1). h(-1) maintenance dose) of midazolam were administered for 60 min. Immediately after the end of midazolam administration, Group 1 received no study drug; Group 2 was infused small-dose (0.004 mg. kg(-1). h(-1)) flumazenil; Group 3 was infused with large-dose (0.02 mg. kg(-1). h(-1)) flumazenil. We assessed diaphragm muscle function (contractility and electrical activity) by transdiaphragmatic pressure (Pdi) and integrated electrical activity of the diaphragm (Edi). After midazolam was administered in each group, Pdi at low-frequency (20-Hz) and high-frequency (100-Hz) stimulation decreased from baseline values (P < 0.05), and values of Edi at 100-Hz stimulation were less than those obtained during baseline (P < 0.05). In Group 1, Pdi and Edi to each stimulus did not change from midazolam-induced values. In Groups 2 and 3, with an infusion of flumazenil, Pdi at both stimuli and Edi at 100-Hz stimulation increased from midazolam-induced values (P < 0.05). The increase in Pdi and Edi was more in Group 3 than in Group 2 (P < 0.05). We conclude that flumazenil recovers the diaphragm muscle dysfunction (reduced contractility and inhibited electrical activity) caused by anesthetic doses of midazolam in dogs. ⋯ In dogs, flumazenil recovers diaphragm muscle dysfunction (reduced contractility and inhibited electrical activity) caused by midazolam in a dose-related manner.
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Anesthesia and analgesia · Oct 2002
Hemodilution with albumin, but not Hextend, results in hypercoagulability as assessed by Thrombelastography in rabbits: role of heparin-dependent serpins and factor VIII complex.
Isovolemic hemodilution (IVHD) has been advocated as an effective method of reducing the need for transfusion but has been associated with hypercoagulability. We tested the hypothesis that IVHD enhances hemostatic function by decreasing circulating antithrombin activity in rabbits. Furthermore, it was determined whether different replacement solutions would affect hemostasis. Sedated rabbits were randomly assigned to groups that underwent IVHD (40% blood volume removed) with 5% human albumin (n = 10) or a 6% hetastarch solution (Hextend). Antithrombin and Factor VIII complex (VIII:C) activities were determined, and thrombelastography(R) was performed with or without platelet inhibition. IVHD resulted in a significant (P < 0.05) decrease in antithrombin (32%-39%) without fluid-specific differences observed. VIII:C did not change in the albumin group, whereas the hetastarch group had a significant (P < 0.05) decrease (43%) in VIII:C that was also significantly (P < 0.05) less than the albumin group. The time to clot initiation was decreased, and the rate of clot formation increased significantly via thrombelastography(R) in albumin animals. No significant change in clot kinetics was observed in hetastarch animals. In rabbits, the primary determinant of hemostasis after IVHD was the interaction of changes in antithrombin activity and VIII:C. These data serve as a rational basis to determine whether IVHD-mediated hypercoagulability encountered clinically may be attenuated or exacerbated by the choice of colloid administered. ⋯ Isovolemic hemodilution (IVHD) is associated with hypercoagulability. Rabbits hemodiluted with albumin, but not Hextend, became hypercoagulable secondary to a loss of antithrombin activity with simultaneous maintenance of Factor VIII complex activity (VIII:C). Hextend-treated animals had proportionate decreases in both antithrombin activity and VIII:C. IVHD-mediated hypercoagulability encountered clinically may be attenuated or exacerbated by the choice of colloid administered.