Anesthesia and analgesia
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Anesthesia and analgesia · Feb 2000
Comparative StudyComparison of NAD 6000 and servo 900C ventilators in an infant lung model.
We compared the ability of the NAD 6000 (North American Dräger, Telford, PA) and the Servo 900C (Siemens-Elema AB, Solna, Sweden) anesthesia ventilators to maintain precise delivery of small tidal volumes (V(t)) and positive end-expiratory pressure using an infant test lung model. A variety of ventilator and lung model settings were selected to test clinical conditions simulating normal and extremely compromised lung function. Differences in ventilator output were analyzed by using an independent t-test with P <0.05 considered significant. With the ventilators set to deliver a V(t) of 30 mL, the actual delivered V(t) was significantly better for the NAD 6000 (25 +/- 2 mL) compared with the Servo 900C (18 +/- 3 mL), P <0.001. When the ventilators were set to deliver 100 mL V(t), their delivered V(t) were not significantly different, NAD 6000 (66 +/- 19 mL) and Servo 900C (60 +/- 12 mL), P = 0.09. The exhaled V(t) read by the anesthesia machines was significantly closer to the delivered V(t) for the NAD 6000 (11 +/- 9 mL) compared with the Servo 900C (37 +/- 11 mL), P < 0.001. Both ventilators maintained the end expiratory pressure delivered to the test lung within 2 cm H(2)O of the set positive end-expiratory pressure on average. As the conditions changed requiring the ventilator to develop a higher peak inflating pressure, both ventilators showed a decrease in V(t) delivered, which was proportionate to the tubing compression volume loss. ⋯ The NAD 6000 (North American Dräger, Telford, PA) and Servo 900C (Siemens-Elema AB, Solna, Sweden) are able to precisely deliver small Tidal Volumes. They both decreased in performance when tested under extreme conditions. Earlier studies of traditional anesthesia ventilators suggest that the NAD 6000 and Servo 900C are superior pediatric ventilators.
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Anesthesia and analgesia · Feb 2000
In vitro effects of different medium molecular hydroxyethyl starch solutions and lactated Ringer's solution on coagulation using SONOCLOT.
Hydroxyethyl starch (HES) solutions are widely used to replace intravascular volume. HES solutions differ from each other with regard to molecular weight and mode of hydroxyl substitution (degree of hydroxylation, C2:C6 hydroxyethyl ratio, concentration), factors which may have varying effects on coagulation. We studied, in vitro, three different HES preparations (molecular weight/degree of hydroxylation/concentration/C2:C6 ratio of substitution 70.000/0. 5/6%/3.2; Pharmacia & Upjohn Co., Erlangen, Germany; 130.000/0. 4/6%/11.2 and 200.000/0.5/6%/4.6; Fresenius Co., Bad Homburg, Germany) and, for comparison, lactated Ringer's solution (RL) at 33% and 66% dilution with whole blood. The influence of hemodilution was measured by using routine laboratory variables and SONOCLOT (Sonoclot II Coagulation and Platelet Function Analyzer, Sienco Co.) analysis, using a viscoelastic test, on the cellular as well as on the plasmatic hemostatic system. For statistical analysis of quantitative data, we used nonparametric analysis of variance and adequate post hoc tests. Qualitative data were analyzed by using the nonparametric Kruskal-Wallis test. A P value below 0.05 was considered significant. In contrast to the control group with RL, the liquid phase of coagulation (activated clotting time) was slightly affected by the 33% diluted HES solutions. HES 70.000, 130. 000, and 200.000 interfered significantly with the early stage of coagulation as expressed by the clot rate (gel/fibrin formation). Clot maturation and speed of maturation (time to peak) were strongly affected by HES 70.000 at all grades of dilution. HES 130.000 showed a faster clot formation process compared with the other HES solutions. HES 130.000 diluted 33% showed a better clot retraction as compared with the other HES solutions. In conclusion, in vitro hemodilution comparing different medium molecular weight HES solutions reveals that HES 130.000 seems preferable regarding some aspects of clot formation and retraction. RL affected clot formation only minimally, except for the early activation of clotting, which was measured by a shortened activated clotting time. ⋯ We investigated the effect of different hydroxyethyl starch (HES) solutions (70.000, 130.000, 200.000) on coagulation. Regarding clot formation and retraction, HES 130.000 had some advantages over the other tested HES solutions. Lactated Ringer's solution affected coagulation only minimally, except for the early stage of clot formation.
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Anesthesia and analgesia · Feb 2000
Factors influencing the reporting of adverse perioperative outcomes to a quality management program.
Quality management programs have used several data reporting sources to identify adverse perioperative outcomes. We compared reporting sources and identified factors that might improve data capture. Adverse perioperative outcomes between January 1, 1992, and December 31, 1994, were reported to the Department of Anesthesiology Quality Management program by anesthesiologists, hospital chart reviewers, and other hospital personnel using incident reports. The reports were compared for preoperative health status, severity of outcome, and associated human error. Subsequently, personnel representing the various sources were surveyed regarding factors that might affect their reporting of adverse outcomes. Of 37,924 anesthetics, 734 (1. 9%) adverse outcomes were reported, 519 (71%) of which were identified by anesthesiologists, 282 (38%) by chart reviewers, and 67 (9.1%) by incident report. There was no statistically significant difference in reporting rates by anesthesiologists according to preexisting disease, severity of outcome, or presence of human error. Thirteen cases involving human error, however, resulted in disabling patient injury, with a higher rate of self-reporting for these cases (92%, P < 0.05). Rates of reporting by chart reviewers varied (P < 0.05) according to severity of patient illness and severity of outcome. Incident reports identified only 67 adverse outcomes (9.1%), but included a significantly higher percentage of the adverse outcomes involving human error (23.3%, P < 0.05). Twenty attending anesthesiologists, 15 resident anesthesiologists, 29 operating room nurses, 19 postanesthesia care unit nurses, and 6 hospital chart reviewers responded to the survey. Only the potential to improve quality of patient care influenced or strongly influenced a decision by all groups to report an adverse outcome to a peer review process. Physician self-reporting is a more reliable method of identifying adverse outcomes than either medical chart review or incident reporting. ⋯ Physician self-reporting is a more reliable method of identifying adverse outcomes than either medical chart review or incident reporting. Reporting by chart reviewers is biased both by the severity of outcome and severity of patient illness, whereas incident reports tend to focus on human error. All groups feel compelled to report adverse outcomes when the data may result in improved patient care.