Stroke volume variation and pleth variability index to predict fluid responsiveness during resection of primary retroperitoneal tumors in Hans Chinese

Respiration variation in arterial pulse pressure (ΔPP) and pulse oximetry plethysmographic waveform amplitude (ΔPOP) are accurate predictors of fluid responsiveness in mechanically ventilated patients. We hypothesized that stroke volume variation (SVV) and pleth variability index (PVI) can predict fluid responsiveness in mechanically ventilated patients during major surgical procedures in Hans Chinese. This prospective study consisted of fifty-five Hans Chinese patients undergoing resection of primary retroperitoneal tumors (PRPT). During the surgical procedures, hemodynamic data [central venous pressure (CVP), cardiac index (CI), stroke volume index (SVI), SVV, and PVI] were recorded before and after volume expansion (VE) (8 ml•kg-1 of 6% hydroxyethyl starch 130/0.4). Fluid responsiveness was defined as an increase in SVI ≥ 10% after VE. Four patients were excluded from analysis for arrhythmia or obvious hemorrhage during VE. Baseline SVV correlated well with baseline PVI and the changes in SVV was correlated with the changes in PVI (p < 0.01) after VE. There were significant increases of CI, SVI and decreases of SVV, PVI in responder (Rs) after VE. ROC results showed that the areas for SVV, PVI were significantly higher than the areas for CI, MAP, CVP, PI (p < 0.05). The best threshold values to predict fluid responsiveness were more than 12.5% for SVV and more than 13.5% for PVI in the real surgical setting. The baseline value of SVV, and PVI correlated significantly with volume-induced changes in SVI (p < 0.01). Both SVV and PVI could be used to predict intraoperative fluid responsiveness during resection of PRPT in Hans Chinese.

Performance of bispectral index and auditory evoked potential monitors in detecting loss of consciousness during anaesthetic induction with propofol with and without fentanyl

BACKGROUND AND OBJECTIVE

To investigate and compare the performance of bispectral index (BIS) and auditory evoked response index (AAI) in detecting the transition from consciousness to unconsciousness during anaesthesia induction by propofol, alone and in combination with fentanyl.

METHODS

Anaesthesia was induced with either an intravenous infusion of 30 mg kg(-1)h(-1) of propofol plus 2 microg kg(-1) of fentanyl (Group PF, n = 20) or an intravenous infusion of 30 mg kg(-1) h(-1) of propofol plus normal saline (Group P, n = 20). BIS, AAI and the doses of propofol administered were recorded at the end-point of unresponsiveness to verbal commands. The propofol plasma concentration was also measured.

RESULTS

The propofol dose and plasma propofol concentration required to achieve loss of consciousness were significantly lower in patients pretreated with fentanyl (P < 0.001). The mean BIS value at loss of consciousness was significantly different between the two groups (74.10 in Group PF vs. 60.80 in Group P) (P < 0.001). However, no difference in the AAI was seen between the two groups at loss of consciousness (32.90 in Group PF vs. 31.80 in Group P) (P > 0.05). In both groups, the regression analysis values (r-values) between BIS and plasma propofol concentrations at the onset of unconsciousness were higher than those between AAI and propofol concentrations (0.553 vs. 0.180 in Group P; 0.432 vs. 0.308 in Group PF).

CONCLUSIONS

These results show that a fentanyl bolus is effective in augmenting the hypnotic effect of propofol during anaesthesia induction. AAI appears to be able to measure the transition from consciousness to unconsciousness at similar values, regardless of whether or not fentanyl pretreatment is used whereas the BIS values were not independent of fentanyl pretreatment. This suggests that AAI may be a better indicator of conscious status during propofol/fentanyl anaesthesia, where it appears to be independent of the anaesthesia regimen.

The effect of ketamine on clinical endpoints of hypnosis and EEG variables during propofol infusion

BACKGROUND

We studied the effect of variable doses of ketamine on the endpoints of hypnosis, e.g., unresponsiveness to verbal commands (UVC), loss of eyelash reflex (LER), and inhibition of body movement response with or without sneezing to nasal membrane stimulation (INBMR), and processed EEG variables, e.g., bispectral index (BIS), 95% spectral edge frequency (SEF) and median frequency (MF) during propofol infusion.

METHODS

Forty-eight patients received either propofol infusion, 30 mg.kg-1.h-1 (Group P; n = 12) or ketamine bolus, 0.25, 0.5 or 0.75 mg i.v., followed by propofol infusion, 30 mg.kg-1.h-1 + variable dose ketamine infusion, 0.25, 0.5 or 0.75 mg.kg-1.h-1 (Groups PK0.25, PK0.5 and PK0.75; n = 12 each) until UVC, LER and INBMR. BIS, 95% SEF and MF values were monitored and recorded at the endpoints of hypnosis. Propofol and ketamine concentrations were measured at INBMR.

RESULTS

Propofol infusion, 30 mg.kg-1.h-1, induced UVC, LER and INBMR at BIS: 65 +/- 2, 63 +/- 9 and 33 +/- 7; 95% SEF: 17 +/- 3, 17 +/- 4 and 14 +/- 3; and MF values of 5 +/- 2, 5 +/- 3 and 3 +/- 2, respectively. With adjunctive ketamine (Groups PK0.5 and PK0.75), the hypnotic endpoints were achieved at higher BIS and 95% SEF values and lower propofol doses and concentrations as compared to Groups P and PK0.25 (9.9 +/- 5.8 and 9.4 +/- 3.4 vs. 13.4 +/- 4.5 and 14 +/- 5.8 micrograms.ml-1).

CONCLUSIONS

Our results suggest additive interaction between propofol and ketamine (Groups PK0.5 and PK0.75) for achieving the hypnotic endpoints; however, ketamine did not depress the EEG variables in proportion to its hypnotic effect. The paradoxically higher BIS and 95% SEF values at the hypnotic endpoints may be due to lower propofol concentrations and/or no effect of ketamine on the EEG variables.

Hypnotic endpoints vs. the bispectral index, 95% spectral edge frequency and median frequency during propofol infusion with or without fentanyl

Hypnotic endpoints and/or EEG variables, e.g. bispectral index, 95% spectral edge frequency and median frequency, have been studied to monitor anaesthetic (hypnotic) depth during total intravenous anaesthesia. In this study, the relation between the hypnotic endpoints of unresponsiveness to verbal commands, loss of eyelash reflex and body movement response to mechanical nasal membrane stimulation vs. bispectral index, 95% spectral edge frequency and median frequency during propofol anaesthesia with or without fentanyl is presented. Forty-two patients were randomly assigned to receive either propofol infusion, 30 mg kg-1 h-1 (n = 22), or propofol infusion, 30 mg kg-1 h-1 + fentanyl bolus, 2 micrograms kg-1 i.v. (n = 20). Bispectral index, 95% spectral edge frequency and median frequency and propofol doses were monitored and recorded at unresponsiveness to verbal commands, loss of eyelash reflex and inhibition of nasal body movement response. The bispectral index values were significantly higher in the propofol + fentanyl compared with the propofol group, i.e. 74.7 +/- 10.9, 73.1 +/- 10.5 and 47.1 +/- 9.2 vs. 65.8 +/- 9.8, 59.6 +/- 10 and 33.8 +/- 5.7 at unresponsiveness to verbal commands, loss of eyelash reflex and inhibition of nasal body movement response respectively. Doses of propofol for achieving the hypnotic endpoints were significantly lower in the propofol + fentanyl compared with the propofol group. Plasma propofol concentrations at inhibition of nasal body movement response were lower in the propofol + fentanyl compared with the propofol group (9.2 +/- 2.0 micrograms mL-1 vs. 14.1 +/- 4.2 micrograms mL-1). Our results suggest that fentanyl pretreatment potentiates the effects of propofol and achieves the hypnotic endpoints at higher bispectral index values and lower propofol doses and concentrations (measured at inhibition of nasal body movement response).

[Electroconvulsive therapy decreased bispectral index--a case report]

A 28-year old female schizophrenic patient underwent electroconvulsive therapy (ECT) under propofol anesthesia. She received ECT five times, and Bispectral Index (BIS) was recorded four times out of the five ECT. BIS values (mean +/- SD) were 95.3 +/- 1.3 before anesthesia, 38.0 +/- 13.1 after loss of consciousness, 45.3 +/- 12.7 immediately after ECT and 27.3 +/- 11.6 about two minutes after ECT. In conclusion, ECT may decrease BIS during continuous propofol infusion.

Lack of correlation between the reduction of sevoflurane MAC and the cerebellar cyclic GMP concentrations in mice treated with 7-nitroindazole

BACKGROUND

Although inhibition of nitric oxide synthase (NOS) has been reported to be antinociceptive and to reduce the threshold of general anesthesia, the mechanism of action is largely unknown. Specifically, the relation between the minimum alveolar concentration (MAC)-reducing effects of NOS inhibition and cyclic guanosine monophosphate (cGMP) concentrations in the brain has not been defined. To further characterize the effects of NOS inhibition, the authors studied the relation between the MAC of sevoflurane and the cGMP concentration of the brain after acute and chronic treatment with a neuronally selective NOS inhibitor, 7-nitroindazole (7-NI).

METHODS

Sevoflurane MAC and cerebellar cGMP concentrations were determined in mice after acute intraperitoneal administration or after 1, 2, 3, and 4 days of gavage feeding of 7-NI. After acute or chronic treatment with 7-NI, the mice were separated into two groups. Sevoflurane MAC was measured by a tail-clamp method in the first group, and cerebellar cGMP concentrations were measured by enzyme-linked immunosorbent assay in the second group of the mice.

RESULTS

In mice, acute intraperitoneal administration of 7-NI dose dependently decreased sevoflurane MAC and cerebellar cGMP; and 4-day-long gavage feeding with 7-NI (500 mg/ kg, every 8 h) time dependently decreased cerebellar cGMP, but sevoflurane MAC was reduced only for the first 2 days and returned to its baseline after 3 days of 7-NI feeding.

CONCLUSIONS

Although an acute selective inhibition of neuronal NOS decreases sevoflurane MAC and cerebellar cGMP concentrations in mice, there was a dissociation between the two parameters during long-term neuronal NOS inhibition. There may be cGMP-independent compensatory mechanisms that mediate nociception when NOS is chronically inhibited.

[Pharmacokinetics of propofol and ketamine during and after total intravenous anesthesia with propofol, fentanyl and ketamine for pediatric patients]

Pharmacokinetics of propofol and ketamine during propofol-fentanyl-ketamine (PFK) anesthesia for pediatric surgery was studied. Plasma levels of propofol (Pp) were maintained approximately at 2.5 micrograms.ml-1 during surgery. Fifteen minutes after the cessation of propofol infusion, Pp decreased to 1.5 micrograms.ml-1. Plasma levels of ketamine (Pk) were maintained at 150-200 ng.ml-1 during the surgery. After the cessation of ketamine infusion, Pk decreased as quickly as Pp. Pk values at 15 minutes and 120 minutes after the cessation of the infusion were 93 ng.ml-1, 24 ng.ml-1, respectively. On the other hand, plasma norketamine (Pn) levels increased gradually during surgery and stayed at 100-150 ng.ml-1 after the end of ketamine infusion to play an important role in post-operative sedation and pain relief. In conclusion, pharmacokinetics of propofol and ketamine in pediatric patients was similar to that in adult patients. PFK anesthesia can be used safely for pediatric as well as for adult patients.

[Clinical indication of propofol for pediatric patients--pharmacokinetics of propofol and ketamine during and after total intravenous anesthesia with propofol, fentanyl and ketamine (PFK) in a neonate]

A 60-day-old neonate boy received hepatic portojejunostomy for biliary atresia under PFK. Pharmacokinetics of propofol and ketamine during and after PFK was also studied. Plasma levels of propofol (Cp) and ketamine (Ck) were maintained at 2 to 3 micrograms ml-1 and at 200 to 300 ng ml-1 during surgery, respectively. Both Cp and Ck decreased quickly after the end of infusions. From the pharmacokinetic point of view, PFK may be safely applied even for neonates.

Haemodynamic and electroencephalograph responses to intubation during induction with propofol or propofol/fentanyl

PURPOSE

To observe the changes in EEG bispectral index (BIS), 95% spectral edge frequency (95% SEF) and median frequency (MF) with haemodynamic changes to intubation during induction with propofol or propofol and 2 micrograms.kg-1 fentanyl i.v.

METHODS

Twenty four ASA I-II patients were randomized to receive either propofol infusion preceded by normal saline (group P, n = 12) or propofol preceded by 2 micrograms.kg-1 fentanyl (group PF, n = 12). Intubation was performed five minutes after maintenance of BIS within 45 +/- 5. EEG and haemodynamic variables were recorded at before induction, and before and after intubation.

RESULTS

Haemodynamic responses to intubation were greater in group P than in group PF (P < 0.05). Postintubation SBP, DBP and HR increased, compared with preinduction values, more in group P than in group PF. Postintubation BIS values increased from 45.5 +/- 3.5 and 44.2 +/- 4.1 to 51.1 +/- 4.1 and 50.9 +/- 5.3 in groups P and PF, respectively, compared with preintubation values. The BIS values were not different between treatment groups before and after intubation, and 95% SEF and MF values did not increase after intubation.

CONCLUSION

Fentanyl, 2 micrograms.kg-1 i.v., blunted the haemodynamic responses to intubation, but failed to attenuate the arousal of cerebral cortical activity. The different haemodynamic responses postintubation but similar BIS and 95% SEF changes in the two groups suggest that BIS or 95% SEF cannot predict the haemodynamic responses to intubation during anaesthesia induction with propofol and fentanyl.

[Detective efficacy of abnormality during mechanical ventilation]

The sensitivity of expired oxygen concentration (FeO2), oxygen concentration difference between inspiration and expiration (FiO2-FeO2), end-tidal CO2 (ETCO2) and pulse oxymetry (SpO2) in monitoring of several abnormal states during mechanical ventilation were compared in 10 patients. FiO2-FeO2 and FeO2 were found as sensitive as ETCO2 in monitoring hypoventilation. Oxygen analyzer located at the expiratory limb provided more information than at the inspiratory one. SpO2 was a rather insensitive detector for hypoventilation or even interruption of ventilation if FiO2 values was higher than that in ambient air. ETCO2 was a valuable estimate of adequate ventilation and CO2 elimination.