Comparison of Desflurane-induced Circulatory Responses by the Rate of Increase in Inhaled Desflurane Concentration / 대한마취과학회지

BACKGROUND: A rapid increase in desflurane concentration induces tachycardia and hypertension and increases plasma catecholamine concentration. No clinical study is available as to whether the desflurane-induced circulatory responses is blunted by the rate of increase in inhaled desflurane concentration although there were many studies about methods to blunt the circulatory responses. The current study examined to compare desflurane-induced circulatory responses by the rate of increase in inhaled desflurane concentration. METHODS: Unpremedicated sixty ASA physical status 1 patients, aged 20-60 years, scheduled for elective surgery under general anesthesia were randomly allocated into one of two groups. The inspired concentration of desflurane via mask was increased to 12.0 vol% abruptly (group 1), or during 120 seconds (group 2). The target was to produce an end-tidal concentration of desflurane (ETdesf) of 10.0 vol% which was maintained until the end of the study by adjusting the vaporizer setting, when necessary. Heart rate (HR), mean arterial pressure (MAP), cardiac index (CI), systemic vascular resistance (SVR), ETdesf, end-tidal concentration of carbon dioxide, and peripheral oxygen saturation were measured at baseline and every 30 seconds for 5 minutes after inhalation of desflurane and for 2 minutes after intubation. RESULTS: HR, blood pressure, and CI were significantly increased in two groups compared with baseline, but significant differences in maximum values were not observed between two groups. There were no significant differences between groups of the ETdesf at the maximal HR and MAP. Incidences of hypertension and tachycardia were lesser in slowly increased inhaled desflurane concentration (group 2) than abruptly increased group (group 1). CONCLUSIONS: The present study demonstrates that increasing inhaled desflurane concentration slowly for mask ventilation is partially effective in attenuating desflurane-induced circulatory responses.

Comparison of the Circulatory Responses of Autotransfusion and Fluid Resuscitation in Dogs with Hemorrhagic Shock / 대한마취과학회지

Fluid resuscitation is a basic treatment in hemorrhagic shock. We compared the circulatory responses to fluid resuscitation of 10% pentastarch with those of fresh whole blood and plasmanate in hemorrhagic shock. Eighteen mongrel dogs were bled 24 ml/kg and replaced by equivalent amounts of fresh whole blood(n=6, group B), pentastarch(n=6, group P) and plasmanate(n=6, group PL). Hemodynamic measurements and calculations were performed before and after bleeding and after volume therapy. The decrease of hematocrit and platelet count after volume replacement indicate that hemodilutional effect was maximum 30 min after volume therapy and significantly greater in group P than PL(p<0.05). Central venous pressure(CVP), pulmonary capillary wedge pressure(PCWP) and cardiac index(CI) were increased to 146-189%, 146-172% and 146-175% in group P, respectively during 60 min. These changes were significantly greater than group B and PL(p<0.05). There was delayed recovery of mean arterial pressure in group PL(92% 30 min after volume therapy) compared with group B and P(92% and 93% 5 min). Also group P and PL showed significant prolongation in prothrombin time and partial thromboplastin time during experiment(120 min) and these were significantly more prolonged in group P than PL(P<0.05). And group P showed similar O transport and O extraction ratio to those of group B. The increases in plasma catecholamine were observed after hemorrhage, but no significant changes 5 and 30 min after volume therapy. This suggests that the neurohumoral response to hemodilution was not marked. Mixed venous O2 saturation(SvO2) was directly proportional to CI during experiment(r=0.69, p<0.01), indicating that SvO2 can represent CI during shock and volume therapy. In conclusion, l0% pentastarch is useful as a substitute for fresh whole blood or plasmanate.

Changes of Circuratory Response during Intubation by Small Dose Fentanyl / 대한마취과학회지

Induction of general anesthesia with tracheal intubation is routine procedure but causes significant tarchycardia and hypertension. Many approaches have been tried to attenuate these circulatory response. The effects of small dose fentanyl on arterial pressure and heart rate increase during intubation were studied in 40 normotensive patients, who were randomly allocated to two groups, receiving saline (Control group) or fentanyl 2ug/kg (Fentanyl group), in a double blind fashion during anesthetic induction with thiopental 5mg/kg. Systolic, diastolic, mean arterial pressure and heart rate were measured and rate pressure product was calculated. All parameters were significantly different between two groups (p<0,05) and control group was significant increase in blood pressure and heart rate compared with pre-induction value but fentanyl group was relatively small changes of blood pressure and heart rate (p<0.01). After tracheal intubation, incresed blood pressure was returned to pre-induction value within two to three minutes in fentanyl group but heart rate was not returned pre-induction value within 5 minutes. Dose of fentanyl that are low enough to cause any side effects of drug itself, no notable side effects were observed during study and recovery.

Circulatory Responses to Acute Isovolemic Hemodilution in Hypoxic Dogs / 대한마취과학회지

The circulatory responses to acute isovolemic hemodilution were studied in nine mongrel dogs in hypoxic(FIO2=0.15) environment. The animals were bled 20ml/kg of blood. The shed blood was replaced by equivalent amounts of low molecular weight extran(LMWD). Hemodynamic measurements and calculations were performed in control normoxic period, hypoxic period before bleeding, hypoxic period after fleeding and after hemodilution with LMWD. By hemodilution, Hb and Hct were decreased from 13.6+/-0.8gm/dl and 41+/-2% to 12.9+/-0.9gm/dl and 21+/-2%, respectively. Hypoxia itself did not cause any hemodynamic changes. Bleeding caused significant increases in SVR(60%) and PVR(77.9%), and resulted in decreases in CI(40.0%), TI(32.7%) and PCWP(2.0%) compared with the data in control period. Hemodilution reversed hemodynamic changes induced by bleeding. PVR returned to normal and SVR was rather decreased by 24.2%, CI, PCWP and CVP were increased by 25.4%, 6.0%, and 37.5%, respectively. The parameters such as HR and RPP which might be related to oxygen consumption were decreased by 10.6%, compared with control data. This study demonstrated that, in spite of lowered arterial oxygen content during hemodilution, tissue oxygen supply and cardiac performance might be well maintained by combined effects of decreased afterload and oxygen consuming factors, and increased preload. In conclusion, acute isovolemic hemodilution with LMWD might be a safe tolerable method in the aspects of circulatory response in hypoxic dogs.