Anesthesia and analgesia
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Anesthesia and analgesia · Oct 2002
Randomized Controlled Trial Comparative Study Clinical TrialThe effects of perioperatively administered colloids and crystalloids on primary platelet-mediated hemostasis and clot formation.
To explore whether routinely administered colloids and crystalloids influence the hemostatic system, we studied 60 patients undergoing knee replacement surgery during randomized intravascular fluid administration using 6% hydroxyethyl starch 200/0.5 (HES) or 4% modified gelatin (GEL) in addition to a basal infusion of lactated Ringer's solution (RL), or exclusively RL. In addition to routine coagulation tests, measurements of coagulation factors were performed. Also, functional measurements of the in vitro bleeding time by use of the platelet function analyzer (PFA-100 and ROTEG analysis (ROTEG(R); extrinsically and intrinsically [Ex; In] activated measurements of clotting time, CT [s]; clot formation time, CFT [s]; clot strength, A20 [mm]; fibrinogen component of the clot, FibA20 [mm]; and maximal clot elasticity) were used. Time dependency of variables was analyzed with a repeated-measures analysis of variance (all groups pooled); differences between groups were detected by comparing the calculated area under the curve (AUC(A-D)). For all variables, except ExCT, ExCFT, and InCFT, a significant time dependency was demonstrated, indicating that impaired platelet-mediated hemostasis and clot formation occurred with IV administration of fluids. Total clot strength, fibrinogen part, and clot elasticity decreased significantly more in the colloid groups than in the RL group (InA20: HES, -13.0 mm; GEL, -11.5 mm; RL, -1.3 mm; P = 0.042; FibA20: HES, -10.5 mm; GEL, -6.0 mm; RL, -1.3 mm: P < 0.0001; MCE: HES, -48; GEL, -35; RL, -15.8; P < 0.0001). The decrease in fibronectin concentrations was significantly smaller with GEL as compared with HES, whereas a weak trend toward a larger decrease in fibrinogen concentrations was observed with both colloids. Results show that colloid administration reduces final clot strength more than does RL alone, which also exhibited effects, albeit minor, on the coagulation system. The reduction in total clot strength was due to impaired fibrinogen polymerization, resulting in a decreased fibrinogen part of the clot and reduced clot elasticity. ⋯ Our data suggest that during deliberate colloid administration, critically impaired fibrinogen polymerization and reduced fibrinogen concentrations might be reached earlier than expected. Therefore, maintaining fibrinogen concentrations seems essential when continuing blood loss is bridged by colloid infusion until transfusion triggers are reached, especially in patients already exhibiting borderline fibrinogen levels at baseline.
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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 Trial"Motion-resistant" pulse oximetry: a comparison of new and old models.
Several pulse oximeter manufacturers have recently developed instruments that are claimed to be resistant to the effects of patient motion. We performed a laboratory volunteer experiment to compare the performances of several of these instruments, as well as some older models, during combinations of motion and hypoxemia. Twenty oximeters were studied. ⋯ IMPLICATIONS. New improvements in pulse oximeter technology have resulted in significantly better accuracy and reliability during patient motion. The Masimo pulse oximeter demonstrated the best performance of the 20 instruments tested.
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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.