Infusão contínua de propofol associado ao fentanil ou sufentanil em cadelas submetidas a ovariosalpingo-histerectomia

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Índice biespectral, variáveis intracranianas e cardiovasculares em cães anestesiados com diferentes doses de infusão de propofol, associados ou não ao óxido nitroso

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Morfina em diferentes doses associadas à levobupivacaína ou à ropivacaína pela via peridural em cadelas para realização de ovariossalpingohisterectomia eletiva

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Infusão contínua de morfina ou fentanil, associados à lidocaína e cetamina, em cães anestesiados com isofluorano

A técnica de analgesia multimodal, por meio da infusão contínua de fármacos, pode ser empregada para diminuir a incidência de sensibilização central durante a anestesia. Avaliaram-se as características cardiorrespiratórias, durante o procedimento de artroscopia de joelho, em cães anestesiados com isofluorano e monitorados por meio do índice biespectral, submetidos à infusão contínua de morfina ou fentanil, associada à lidocaína e cetamina. Utilizaram-se 16 cães adultos, machos ou fêmeas, os quais foram distribuídos aleatoriamente em dois grupos, denominados MLK - que recebeu morfina (3,3μg/kg/min), lidocaína (50μg/kg/min) e cetamina (10μg/kg/min) ou FLK - em que foi substituída a morfina pelo fentanil (0,03μg/kg/min). Os cães foram pré-tratados com levomepromazina (0,5mg/kg IV), induzidos à anestesia com propofol (5mg/kg) e mantidos com isofluorano, ajustando-se a concentração para obterem-se valores de índice biespectral entre 55 e 65. As mensurações da frequência cardíaca (FC), dos parâmetros eletrocardiográficos (ECG), das pressões arteriais sistólica (PAS), diastólica (PAD) e média (PAM), da tensão de dióxido de carbono expirado (EtCO2), da saturação de oxi-hemoglobina (SpO2), da frequência respiratória (FR) e da temperatura esofágica (T) iniciaram-se 30 minutos após a indução (M0) e continuaram após o início da infusão das soluções, em intervalos de 15 minutos (M15 a M75). Diferenças entre os grupos foram registradas para duração do complexo QRS (M60), para FC e T, entre M30 e M75, com MLK apresentando médias maiores que FLK, que registrou médias maiores que MLK para a SpO2 (M60), para os intervalos QT (M30 e M75) e RR (M0, M60 e M75). Concluiu-se que o emprego de morfina ou fentanil, associados à lidocaína e cetamina, promove efeitos semelhantes e não compromete as características avaliadas.

Effects of continuous rate infusion of butorphanol in isoflurane-anesthetized calves

PURPOSE:To assess the hemodynamic changes and bispectral index (BIS) following administration of a continuous rate infusion (CRI) of butorphanol in isoflurane-anesthetized calves.METHODS: Eight calves weighing 110 ± 12 kg were included in the study. Anesthesia was induced with 5% isoflurane in O2 delivered via face mask and maintained with end-tidal concentration of 1.4%. IPPV was set to a peak inspiratory airway pressure of 15 cmH2O and respiratory rate of six breaths minute-1. Forty minutes after the start of anesthetic maintenance, 0.1 mg kg-1butorphanol was administered intravenously, followed by a CRI of 20 µg kg-1 minute-1. Hemodynamic variables and BIS were recorded before butorphanol administration (T0), and at 10, 20, 40 and 80 minutes following the CRI. Anesthesia was discontinued after the last recording and the calves were allowed to recover. The time to sternal recumbency (SRE) and standing (ST) were evaluated.RESULTS: There were no significant differences between the moments in all hemodynamic variables and BIS. The time to SRE and ST was 9 ± 5 and 14 ± 7 minutes, respectively.CONCLUSION: The continuous rate infusion did not produce clinically relevant changes in hemodynamic or bispectral index values compared to baseline in mechanically ventilated and unstimulated calves anesthetized at 1.4% isoflurane.

Efeitos hemodinâmicos da anestesia em plano profundo com infusão intravenosa contínua de propofol ou propofol associado à lidocaína em cães

The hemodynamic effects of total intravenous anesthesia with propofol or propofol in combination with lidocaine were investigated in 12 dogs. In the P group (n=6), the dogs received a loading dose (LD) of 6mg kg-1 of propofol followed by a constant rate infusion (CRI) of 1.25mg kg-1 min-1. In the PL group (n=6), dogs received a LD of 6mg kg-1 of propofol and 1.5mg kg-1 of lidocaine followed by CRIs of 1.0mg kg-1 min-1 and 0.25mg kg-1 min-1 of propofol and lidocaine, respectively. The animals were instrumented for measurement of hemodynamic variables and bispectral index (BIS), recorded at 75, 90, 105 and 120 minutes during anesthesia. Cardiac index, stroke index, systolic, diastolic and mean arterial blood pressures were lower in the P group compared to the PL group (P<0.05). There were no significant differences between groups in heart rate, systemic vascular resistance index and BIS. Plasma concentrations of propofol were lower in group PL than in group P (medians of 5.7 to 6.1mg mL-1 in the P group versus 3.1 to 3.7mg mL-1 in the PL group). Measured lidocaine plasma concentrations (medians of 2.27 to 2.51mg mL-1) were in the range that result in analgesia and were below values that result in toxicity in dogs. The BIS values observed in the two groups of dogs were compatible with deep anesthesia (mean values of 43-46 and 45-49 in groups P and PL, respectively). Maintenance of deep anesthesia with lidocaine-propofol causes less cardiovascular depression than equipotent doses of propofol alone.

Cardiorespiratory and antinociceptive effects of two different doses of lidocaine administered to horses during a constant intravenous infusion of xylazine and ketamine

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relação do índice bispetral e da taxa de supressão do traçado do eletroencefalograma com disfunção cognitiva pós-operatória em cirurgia de revascularização do miocárdio

Pós-graduação em Anestesiologia - FMB

Efeitos da infusão contínua de tiopental ou propofol em coelhos mantidos em respiração espontânea

Pós-graduação em Cirurgia Veterinária - FCAV

Alteração do índice biespectral antes e após estimulação elétrica ou mecânica em cães anestesiados pelo isofluorano

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Extracorporeal Circulation Interference on Emergence from Anesthesia in Patients Submitted to Myocardial Revascularization

Background and objectives: Extracorporeal circulation (ECC) may change drug pharmacokinetics as well as brain function. The objectives of this study are to compare emergence time and postoperative sedation intensity assessed by the bispectral index (BIS) and the Ramsay sedation scale in patients undergoing myocardial revascularization (MR) with or without ECC. Method: Ten patients undergoing MR with ECC (ECC group) and 10 with no ECC (no-ECC group) were administered with sufentanyl, propofol 2.0 mu g.mL(-1) and pancuronium target controlled infusion. After surgery, propofol infusion was reduced to 1 mu g.mL(-1) and suspended when extubation was indicated. Patients BIS, Ramsay scale and time to wake up were assessed. Results: The ECC group showed lower BIS values beginning at 60 minutes after surgery (no-ECC = 66 +/- 13 and ECC = 53 +/- 14, p = 0.01) until 120 minutes after infusion (no-ECC = 85 +/- 8 and ECC = 73 +/- 12, p = 0.02). Sedation level measured by the Ramsay scale was higher in the ECC group at 30 minutes after the end of the surgery (no-ECC = 5 +/- 1 and ECC = 6 +/- 0, p = 0.021), at the end of infusion (no-ECC = 5 +/- 1 and ECC = 6 +/- 1, p = 0.012) and 5 minutes after the end of infusion (no-ECC = 4 +/- 1 and ECC = 5 +/- 0.42, p = 0.039). Emergence from anesthesia time was higher in the ECC group (no-ECC = 217 +/- 81 and ECC = 319 +/- 118, p = 0.038). Conclusions: There was a higher intensity of sedation after the end of surgery and a longer wake up time in ECC group, suggesting changes in the pharmacokinetics of propofol or effects of ECC on central nervous system.

Closed-loop control of mean arterial blood pressure during surgery with alfentanil: clinical evaluation of a novel model-based predictive controller

BACKGROUND: In contrast to hypnosis, there is no surrogate parameter for analgesia in anesthetized patients. Opioids are titrated to suppress blood pressure response to noxious stimulation. The authors evaluated a novel model predictive controller for closed-loop administration of alfentanil using mean arterial blood pressure and predicted plasma alfentanil concentration (Cp Alf) as input parameters. METHODS: The authors studied 13 healthy patients scheduled to undergo minor lumbar and cervical spine surgery. After induction with propofol, alfentanil, and mivacurium and tracheal intubation, isoflurane was titrated to maintain the Bispectral Index at 55 (+/- 5), and the alfentanil administration was switched from manual to closed-loop control. The controller adjusted the alfentanil infusion rate to maintain the mean arterial blood pressure near the set-point (70 mmHg) while minimizing the Cp Alf toward the set-point plasma alfentanil concentration (Cp Alfref) (100 ng/ml). RESULTS: Two patients were excluded because of loss of arterial pressure signal and protocol violation. The alfentanil infusion was closed-loop controlled for a mean (SD) of 98.9 (1.5)% of presurgery time and 95.5 (4.3)% of surgery time. The mean (SD) end-tidal isoflurane concentrations were 0.78 (0.1) and 0.86 (0.1) vol%, the Cp Alf values were 122 (35) and 181 (58) ng/ml, and the Bispectral Index values were 51 (9) and 52 (4) before surgery and during surgery, respectively. The mean (SD) absolute deviations of mean arterial blood pressure were 7.6 (2.6) and 10.0 (4.2) mmHg (P = 0.262), and the median performance error, median absolute performance error, and wobble were 4.2 (6.2) and 8.8 (9.4)% (P = 0.002), 7.9 (3.8) and 11.8 (6.3)% (P = 0.129), and 14.5 (8.4) and 5.7 (1.2)% (P = 0.002) before surgery and during surgery, respectively. A post hoc simulation showed that the Cp Alfref decreased the predicted Cp Alf compared with mean arterial blood pressure alone. CONCLUSION: The authors' controller has a similar set-point precision as previous hypnotic controllers and provides adequate alfentanil dosing during surgery. It may help to standardize opioid dosing in research and may be a further step toward a multiple input-multiple output controller.

Stimulation induced variability of pulse plethysmography does not discriminate responsiveness to intubation

BACKGROUND: Hypnotic depth but not haemodynamic response to painful stimulation can be measured with various EEG-based anaesthesia monitors. We evaluated the variation of pulse plethysmography amplitude induced by an electrical tetanic stimulus (PPG variation) as a potential measure for analgesia and predictor of haemodynamic responsiveness during general anaesthesia. METHODS: Ninety-five patients, ASA I or II, were randomly assigned to five groups [Group 1: bispectral index (BIS) (range) 40-50, effect site remifentanil concentration 1 ng ml(-1);Group 2: BIS 40-50, remifentanil 2 ng ml(-1); Group 3: BIS 40-50, remifentanil 4 ng ml(-1); Group 4: BIS 25-35, remifentanil 2 ng ml(-1); Group 5: BIS 55-65, remifentanil 2 ng ml(-1)]. A 60 mA tetanic stimulus was applied for 5 s on the ulnar nerve. From the digitized pulse oximeter wave recorded on a laptop computer, linear and non-linear parameters of PPG variation during the 60 s period after stimulation were computed. The haemodynamic response to subsequent orotracheal intubation was recorded. The PPG variation was compared between groups and between responders and non-responders to intubation (anova). Variables independently predicting the response were determined by logistic regression. RESULTS: The probability of a response to tracheal intubation was 0.77, 0.47, 0.05, 0.18 and 0.52 in Groups 1-5, respectively (P<0.03). The PPG variability was significantly higher in responders than in non-responders but it did not improve the prediction of the response to tracheal intubation based on BIS level and effect site remifentanil concentration. CONCLUSION: Tetanic stimulation induced PPG variation does not reflect the analgesic state in a wide clinical range of surgical anaesthesia.

The effects of dexmedetomidine/remifentanil and midazolam/remifentanil on auditory-evoked potentials and electroencephalogram at light-to-moderate sedation levels in healthy subjects

Avoidance of excessively deep sedation levels is problematic in intensive care patients. Electrophysiologic monitoring may offer an approach to solving this problem. Since electroencephalogram (EEG) responses to different sedation regimens vary, we assessed electrophysiologic responses to two sedative drug regimens in 10 healthy volunteers. Dexmedetomidine/remifentanil (dex/remi group) and midazolam/remifentanil (mida/remi group) were infused 7 days apart. Each combination of medications was given at stepwise intervals to reach Ramsay scores (RS) 2, 3, and 4. Resting EEG, bispectral index (BIS), and the N100 amplitudes of long-latency auditory-evoked potentials (ERP) were recorded at each level of sedation. During dex/remi, resting EEG was characterized by a recurrent high-power low-frequency pattern which became more pronounced at deeper levels of sedation. BIS Index decreased uniformly in only the dex/remi group (from 94 +/- 3 at baseline to 58 +/- 14 at RS 4) compared to the mida/remi group (from 94 +/- 2 to 76 +/- 10; P = 0.029 between groups). The ERP amplitudes decreased from 5.3 +/- 1.3 at baseline to 0.4 +/- 1.1 at RS 4 (P = 0.003) in only the mida/remi group. We conclude that ERPs in volunteers sedated with dex/remi, in contrast to mida/remi, indicate a cortical response to acoustic stimuli, even when sedation reaches deeper levels. Consequently, ERP can monitor sedation with midazolam but not with dexmedetomidine. The reverse is true for BIS.

Intrapatient reproducibility of the BISxp monitor

BACKGROUND: The Bispectral Index (BIS) reportedly reflects anesthetic depth. It is recommended that anesthetic agents should be titrated to maintain the BIS between 40 and 60 arbitrary BIS units during anesthesia. For anesthesia providers to follow this recommendation, the monitor should be predictably affected by different anesthetic agents and have good interpatient and intrapatient reproducibility. The authors hypothesized that when two BISxp devices (Aspect Medical Systems, Newton, MA) are placed concurrently on the same patient, their readings are concordant throughout the anesthetic period. METHODS: Simultaneous BIS recordings from two BISxp monitors were obtained during anesthesia at 5-s intervals from 12 participants. RESULTS: In total 22,860 concurrent paired BIS readings were obtained. For 10.7% of the time, there were sustained periods of 30 s or greater where the readings suggested a different depth of anesthesia. For 6% of the time, there were sustained periods of 30 s or greater where the readings differed by 10 or more arbitrary BIS units. The regression coefficient (R) for the two devices was 0.65 (range, 0.35-0.92). There was zero bias between the devices, and the 95% limits of agreement ranged between -18 and +17. CONCLUSION: A conflicting anesthetic management was suggested by the simultaneous BIS readings 10.7% of the time. These results suggest that BISxp does not always provide a reproducible single number. Anesthesia providers should not rely exclusively on the BIS reading when assessing depth of anesthesia.