Continuous Intravenous Infusion Of Propofol Research Articles

Effects of continuous intravenous infusion with propofol on intestinal metabolites in rats.

Microbial metabolites play an important role in regulating intestinal homeostasis and immune responses. Propofol is a common anesthetic in clinic, but it is not clear whether it affects intestinal metabolites in rats. Tail vein puncture was performed after adaptive feeding for 1 month in eight 2-month-old rats and they were given continuous intravenous infusion of propofol for 3 h. The feces of rats were divided into different groups based on time periods, with before and after anesthesia with propofol on days 1, 3 and 7 labeled as groups P, A1, A3 and A7, respectively. The effect of continuous intravenous infusion with propofol on rat fecal metabolites was determined using the non-targeted metabolomics technique gas chromatography coupled with a time-of-flight mass spectrometer analysis. The types and contents of metabolites in rat feces were changed after continuous intravenous infusion with propofol, but the changes were not statistically significant. The contents of the metabolites 3-hydroxyphenylacetic acid and palmitic acid increased from day 3 to 7, and it was shown that the two metabolites were positively correlated at a statistically significant level. Linoleic acid decreased to its lowest level on day 3, and it returned to pre-anesthesia level on day 7. At the same time, linoleic acid metabolism was a metabolic pathway that was co-enriched 7 days after infusion with propofol. Spearman correlation analysis showed that there was significant correlation between some differential metabolites and differential microorganisms. It was observed that zymosterol 1, cytosin and elaidic acid were negatively correlated with Alloprevotella in the A3 vs. P group. In the A7 vs. P group, cortexolone 3 and coprostan-3-one were positively correlated with Faecalibacterium, whilst aconitic acid was negatively correlated with it. In conclusion, the present study revealed statistically insignificant effects of continuous intravenous propofol on the intestinal metabolites in rats.

General anesthesia alters the diversity and composition of the lung microbiota in rat

BackgroundThe lung microbiome plays a crucial role in human health and disease. Extensive studies have demonstrated that the disturbance of the lung microbiome influences immune response, cognition, and behavior. The goal of this study was to investigate the effect of general anesthetics on lung microbiome. MethodsEight-week-old male SD rats received a continuous intravenous infusion of propofol or inhalation of isoflurane for 4 h. 16S rRNA gene amplification from BALF samples was used to investigate the changes in the lung microbiome after interventions. We further performed neurobehavioral assessments to find the differential strains’ association with behavior disorder after isoflurane anesthesia. ResultsThe absolute and relative quantitation of 16S rRNA sequencing data showed that isoflurane altered the diversity and abundance of the lung microbiome in rats more than propofol. Elusimicrobia increased significantly in the isoflurane group. Both EPM and OFT results showed that rats exhibited depression-like behaviors after inhalation of isoflurane. In addition, significant differences were found in the COG/KO/MetaCyc/KEGG pathway enrichment analyses among the groups. ConclusionContinuous inhalation of isoflurane changed the diversity and composition of the lung microbiota in rats, resulting in post-anesthesia depression.

GABRA1 and GABRB2 Polymorphisms are Associated with Propofol Susceptibility.

PurposeTo explore the effect of gene polymorphisms of propofol GABAA receptor and metabolic enzyme on drug susceptibility during the induction period of general anesthesia.Patients and MethodsA total of 294 female patients aged 18–55 years, ASA I–II, who underwent hysteroscopy with intravenous general anesthesia, were included in the study. Anesthesia was induced by continuous intravenous infusion of propofol at 40 mg·kg−1·h−1. Infusion of propofol was ended when both the Modified Observer’s Assessment of Awareness/Sedation scale (MOAA/S scale) decreased to 1 and the BIS index decreased to 60. The time when the MOAA/S scale decreased to 1 and the time when BIS index decreased to 60 was recorded to assess the susceptibility to the sedation effect. The maximum decreased percentage in mean arterial pressure (MAP) within 5 minutes was recorded to assess the susceptibility of cardiovascular response. Venous blood of each patient was collected to identify the presence of genetic variants in the GABRA1, GABRA2, GABRB2, GABRB3, GABRG2, CYP2B6, and UGT1A9 genes using the Sequenom MassARRAY® platform.ResultsAfter receiving propofol infusion, carriers of polymorphic GABRA1 rs4263535 G allele required significantly less time for BIS decreased to 60, while carriers of polymorphic GABRB2 rs3816596 T allele required significantly more time for BIS decreased to 60, carriers of polymorphic GABRA1 rs1157122 C allele and carriers of polymorphic GABRB2 rs76774144 T allele had a significantly less change in MAP.ConclusionGABRB2 rs3816596 and GABRA1 rs4263535 polymorphisms are associated with susceptibility to the sedation effect of propofol. GABRA1 rs1157122 and GABRB2 rs76774144 polymorphisms are associated with the degree of drop in blood pressure after propofol infusion.

Effects of continuous intravenous infusion of propofol on intestinal flora in rats

Under normal circumstances, the gut microbiota, host, and external environment establish a dynamic ecological balance and maintain human health. Once this balance is broken, the intestinal flora dysregulation will form, manifested by changes in the diversity, richness, proportion, location and biological characteristics of the gut microbiota. The hypothesis that propofol alters gut microbes was tested in a rat model with continuous intravenous infusion of propofol. Eight male wistar rats underwent tail vein puncture and catheterization respectively, and were continuously pumped with propofol for 3 h. Feces were collected from each rat before and on the 1 st, 3rd, 7th and 14th days after intervention. Finally, the effect of continuous intravenous infusion of propofol on the intestinal flora of rats was analyzed by high-throughput 16S rRNA gene amplification sequencing. Through high-throughput 16S rRNA gene amplicon sequencing analysis, we found that continuous intravenous infusion of propofol had little effect on intestinal flora in rats. Analysis of Alpha (shannon diversity index) showed that group A-7 was different from group P and group A-1 (P = 0.034), and recovered on the 14th day. Although the species diversity analysis showed a significant difference among the five groups (P = 0.049), the distribution of most fecal samples in the PCoA showed a clustered distribution, indicating similarity. In addition, no significant difference was found in the statistical KEGG difference pathway through LEfSe analysis.

Journal-related Activities and Other Special Activities at the 2020 American Society of Anesthesiologists Meeting.

Journal-related Activities and Other Special Activities at the 2020 American Society of Anesthesiologists Meeting.

Propofol protects against endotoxin-induced myocardial injury by inhibiting NF-κB-mediated inflammation.

This study investigated whether propofol protects against endotoxin-induced myocardial injury by inhibiting NF-κB-mediated inflammation. Thirty clean male SD rats were randomly divided into a control (n=10), a model (n=10) and a propofol group (n=10). The model and propofol groups were injected with lipopolysaccharide (LPS) via the caudal vein to establish animal models of myocardial injury. At the same time, the control group was injected with normal saline via the caudal vein. At 30 min after the injections, the propofol group was treated with a continuous intravenous infusion of propofol, the control and model groups were injected with normal saline, and the three groups were treated continuously for 4 h. The changes in levels of interleukin-1 (IL-1), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in serum were detected via enzyme-linked immunosorbent assay (ELISA). The mRNA expression level of nuclear factor-κB (NF-κB) in myocardial tissues was detected via quantitative real-time polymerase chain reaction (qRT-PCR). The protein expression levels of NF-κB, Bax and Bcl-2 in atrial muscles in each group were measured via Western blotting. The damage of myocardial tissues was detected via hematoxylin eosin (H&E) staining of tissues. Our results showed that compared with those in control group, the levels of IL-1, IL-6 and TNF-α in serum in the model and propofol groups were significantly higher; however, the levels in the model group, were significantly higher than those in the propofol group (P<0.01). The mRNA and protein expression levels of NF-κB in the propofol group were significantly lower than those in the model group (P<0.01). Likewise, the protein expression levels of Bax were significantly lower, while those of Bcl-2 were significantly increased. H&E staining showed that the myocardial tissues in the model group were damaged significantly, but the damage in the propofol group was significantly less severe. Based on our findings, it seems propofol can indeed protect against endotoxin-induced myocardial injury through its inhibition of the NF-κB-mediated inflammatory pathway.

A comparative study between propofol and dexmedetomidine as sedative agents during performing transcatheter aortic valve implantation

ObjectiveThe type of sedative drugs could play a major role in providing hemodynamic stability which is crucial during transcatheter aortic valve implantation (TAVI) procedure. The aim of this study is to compare propofol with dexmedetomidine for conscious sedation during TAVI. DesignA prospective randomized pilot study. PatientsFifty patients with a mean age of 74years, American Society of Anesthesiologists 3-4, complaining from severe aortic stenosis were enrolled in this study to undergo TAVI. InterventionsThe propofol group (group P; n=25) received a bolus dose of 0.5mg/kg propofol followed by a continuous intravenous infusion of propofol at a rate of 30 to 50μg kg−1 min−1, and the dexmedetomidine group (group D; n=25) received dexmedetomidine at a loading dose of 1μg/kg and then a continuous intravenous infusion of dexmedetomidine at a rate of 0.5μg kg−1 h−1. MeasurementsHeart rate, mean arterial blood pressure, number of phenylephrine boluses, oxygen saturation, sedation, and satisfaction scores were measured just after the start of infusion of the sedation drugs and at the end of the procedure. Postoperative complications were also recorded. ResultsThere was a statistically significant reduction in the heart rate in group D in comparison to group P where it was 67.28±6.9beats/min in the first group in comparison to 78±6.9beats/min in the last one (P<.001). The mean arterial blood pressure was statistically significant lower in group D in comparison to group P (58.12±5.4mm Hg in group D vs 68.24±11.4mm Hg in group P; P<.001). Also, the number of phenylephrine boluses was higher in group D than in group P (36.5±7.17 in group D vs 20.6±2.07 in group p; P<.001). No difference between the 2 groups regarding oxygen saturation, sedation, pain, satisfaction scores, and postoperative complications. ConclusionDuring TAVI, dexmedetomidine may be associated with significant hypotension and bradycardia rather than propofol.

Propofol for Status Epilepticus in Pregnancy

We present a 31-year-old pregnant, with prior intractable epilepsy, at 20-weeks of gestation, who was admitted with refractory status epilepticus. Unresponsiveness to first and second line anti-seizure therapy necessitated the use of continuous intravenous infusion of Propofol for 48 hours, which led to clinical and electrographic response without adverse squeal for the mother or the fetus.

Pulse Oximetric and ECG changes during continuous infusion of propofol in medetomidine – pentazocine and midazolam – pentazocine premedicated buffalo calves

Twelve buffalo calves of either sex presented to the clinic with surgical conditions like umbilical hernia, urolithiasis and fractures were utilized to study the effect of continuous intravenous infusion of propofol after premedication with medetomidine – pentazocine and midazolam – pentazocine. The animals were divided into two groups of six animals each. Medetomidine (@ 2.5 μg/kg b.wt.) – pentazocine (@ 0.5 mg/kg b.wt.) and midazolam (@ 0.25 mg/kg b.wt.) – pentazocine (@ 0.5 mg/kg b.wt.) was given intravenously in group I and II respectively. Propofol was given intravenously (@ 4 mg/kg b.wt.) after pre-medication and maintained by continuous intravenous infusion of propofol (@ 0.4 mg/kg b.wt.) in 5 % dextrose normal saline in both groups. Pulse oximetric and electrocardographic changes were recorded at 0, 5,10,15,30 and 60 min. Saturation of oxygen percentage of haemoglobin showed significant (P £ 0.05) difference in both groups but the changes were within the normal range. Electrocardiographic studies did not reveal any abnormalities except slight variations in the amplitude of P wave, T wave and QRS complex in both groups. It is concluded that both anaesthetic drug combinations can be used safely in buffaloes as they did not alter the pulse oximetry and ECG values.

Dexmedetomidine decreases the emergence agitation in infant patients undergoing cleft palate repair surgery after general anesthesia.

BackgroundTo determine whether continuous intravenous infusion of dexmedetomidine (DEX) can affect the incidence of Emergence Agitation (EA) after general anesthesia in infant undergoing cleft palate repair surgery.MethodsForty infants underwent cleft palate repair surgery under general anesthesia were randomly divided into the DEX (D) group and Placebo (P) groups. Patients in group D received continuous intravenous infusion of DEX 0.8 μg · kg-1 · min-1 after the induction. Patients in group P were administered with continuous intravenous infusion of the equivalent volume of normal saline. Both groups were induced with fentanyl 0.005 mg/Kg, propofol 2 mg/Kg and cisatracurium 0.2 mg/Kg. Anaesthesia was maintained with continuous intravenous infusion of propofol (2 mg/Kg · h), remifentanil (0.1 μg/Kg · h), and inhalation of 1 to 3 % sevoflurane.ResultThe heart rate (HR) in group P was significant higher than that in group D at the time of operation (P < 0.05), postoperative 15 min, 30 min and the time of extubation (P < 0.01). The mean arterial pressure (MAP) in group P was higher comparing with MAP in group D at the time of extubation (P < 0.05). The spontaneous eye opening times and spontaneous arm or leg motion times were longer in group D (P < 0.05). The mean agitation scores of patients in group D were significantly lower than that in group P (P < 0.01). However, the incidence of EA in group P and group D was 90 % and 15 % (P <0.05).ConclusionThe continuous intravenous infusion of DEX after induction could significantly reduce the occurrence of EA.Trial registrationThe Chinese Clinical Trial Register ChiCTR-TRC-13003865

Evaluation of Propofol Anaesthesia in Medetomidine-Pentazocine and Midazolam- Pentazocine Premedicated Buffalo Calves

Twelve buffalo calves of either sex presented to the college clinic with various surgical conditions were utilized to study the effect of continuous intravenous infusion of propofol after premedication with medetomidine – pentazocine and midazolam – pentazocine. The animals were divided into two groups of six animals each. Group I animals were premedicated with Medetomidine @ 2.5 μg/kg b.wt. – pentazocine @ 0.5 mg/kg b.wt IV and Group II animals received midazolam @ 0.25 mg/kg b.wt. – pentazocine @ 0.5 mg/kg b.wt. IV.. Propofol was given @ 4 mg/kg b.wt. IV after premedication and maintained by continuous intravenous infusion of propofol @ 0.4 mg/kg b.wt. in 5% dextrose normal saline in both groups. Induction quality was excellent, smooth and attained sternal recumbency rapidly without struggling in both groups. Anaesthetic character, Physiological & haematobiochemical parameters were studied at 0, 5,10,15,30 and 60 minutes following anaesthetic injections. No significant changes were recorded in both the groups. ECG studies did not reveal any abnormalities except slight variations in the amplitude of P wave, T wave and QRS complex in both groups. The study suggests that medetomidine – pentazocine premedication with continuous intravenous infusion of propofol provided better surgical anaesthesia and was compatable and safe in buffalo calves.

The application and evaluation of propofol combined with ketamine bycontinous intravenous Infusion in infant surgery

Objective To assess propofol combined with ketamine anesthesia for surgery in infants of narcotic effect. Methods Anesthesia was maintained by continuous intravenous infusion of propofol 2～4 mg/kg and ketaminel ～2 mg/kg in 60 children, and atropine 0.02 mg/kg was given by the intramuscular injection before 30 minutes preoprative. The changes of the mean arterial pressure(MAP) ,heart rate(HR) ,pulse oxygen saturation(SpO2)and respiratory rate(RR) was observed. Results There was no significant difference between preoperative and different time during operation(P>0.05), and There was no significant difference between dif-ferent time during operation (P>0.05). Conclusion Continuous intravenous infusion of propofol combined with ketamine is safe and effective in infant surgery. The anesthetic effect was satisfied. Key words: Propefol; Ketamine ; Intravenous general anesthesia; Infant surgery

Analgesic effect of dexmedetomidine in a patient with herpetic stomatitis after living-donor lung transplantation

A 31-year-old woman suffering from bronchiolitis obliterans received bilateral living-donor lung transplantation to treat end-stage respiratory failure. After 5 days' mechanical ventilation, the patient was successfully extubated. During mechanical ventilation, the patient was sedated with a continuous intravenous infusion of propofol and dexmedetomidine (DEX). To assuage postoperative pain, morphine was infused, first intravenously, then epidurally. The administration of DEX was continued after extubation to prevent agitation. After the administration of epidural morphine was discontinued on day 10 in the intensive care unit (ICU), the patient complained of pain in the oral cavity. Greater pain was reported after the discontinuation of DEX, and symptoms of tachycardia and dyspnea appeared. A dermatologist diagnosed the oral symptoms as herpetic stomatitis, and a course of treatment with aciclovir was begun. A continuous infusion of DEX was again started on the same day, and was continued until ICU day 13. During the administration of DEX, the oral cavity pain was bearable. The patient was successfully discharged from the ICU on ICU day 13. We conclude that DEX could be used to provide analgesia for herpetic stomatitis after living-donor lung transplantation, at a dosage that achieves appropriate sedation.

Comparison of Propofol With Pentobarbital/Midazolam/Fentanyl Sedation for Magnetic Resonance Imaging of the Brain in Children

Propofol and pentobarbital, alone or combined with other agents, are frequently used to induce deep sedation in children for MRI. However, we are unaware of a previous comparison of these 2 agents as part of a randomized, controlled trial. We compared the recovery time of children after deep sedation with single-agent propofol with a pentobarbital-based regimen for MRI and considered additional variables of safety and efficacy. This prospective, randomized trial at a tertiary children's hospital enrolled 60 patients 1 to 17 years old who required intravenous sedation for elective cranial MRI. Patients were assigned randomly to receive a loading dose of propofol followed by continuous intravenous infusion of propofol or to receive sequential doses of midazolam, pentobarbital, and fentanyl until a modified Ramsay score of >4 was attained. A nurse who was blind to group assignment assessed discharge readiness (Aldrete score > 8) and administered a follow-up questionnaire. We compared recovery time, time to induction of sedation, total sedation time, quality of imaging, number of repeat-image sequences, adverse events, caregiver satisfaction, and time to return to presedation functional status. The groups were similar in age, gender, race, American Society of Anesthesiology physical status class, and frequency of cognitive impairment. No sedation failure or significant adverse events were observed. Propofol offered significantly shorter sedation induction time, recovery time, total sedation time, and time to return to baseline functional status. Caregiver satisfaction scores were also significantly higher in the patients in the propofol group. Propofol permits faster onset and recovery than, and comparable efficacy to, a pentobarbital/midazolam/fentanyl regimen for sedation of children for MRI.

Irreversible brain injury following status epilepticus

Described here is a patient with medically intractable generalized epilepsy who developed status epilepticus (SE) affecting his right cerebral hemisphere for about 48 hours, which led to irreversible injury to that hemisphere. His partial SE did not respond to the first-line therapies, repeated doses of midazolam, or continuous intravenous infusion of propofol. Extensive investigations failed to find a cause of his SE except for a low serum valproic acid. A minor trauma that he suffered 1 week prior to his SE was of questionable significance. Neurological examination, neuropsychological testing, electroencephalography, and magnetic resonance imaging all demonstrated striking abnormalities limited to the affected cerebral hemisphere that did not resolve with repeated testing. This case illustrates permanent focal brain injury following prolonged partial SE in a patient with previously known generalized seizure disorder.

Intraoperative Motor-evoked Potential Monitoring in Scoliosis Surgery: Comparison of Desflurane/Nitrous Oxide With Propofol Total Intravenous Anesthetic Regimens

A prospective, randomized study in a large general hospital setting. During spinal surgery, monitoring motor-evoked potentials (MEPs) is a means of assessing the intraoperative integrity of corticospinal pathways. However, MEPs are known to be sensitive to the effects of anesthetic agents. To compare the use of desflurane or total intravenous anesthetic regimens (TIVA) with multipulse cortical stimulation for intraoperative monitoring (IOM). Twenty consecutive patients (10 in each arm) undergoing scoliosis correction surgery were randomly assigned to 2 equal groups receiving desflurane or TIVA. Inhalational anesthesia was maintained using 66% nitrous oxide in oxygen and a mean end-tidal desflurane concentration of 3.4%. For TIVA, continuous intravenous infusion of propofol was used. For analgesia, fentanyl and morphine were given when required for both groups. Cortical stimulation was achieved with 2 bipolar direct current stimulators connected in parallel by jumper cables. Five equivalent pulses 0.5 ms in duration at 4 ms intervals were delivered at C1C2 positions. MEP recordings were made in the abductor hallucis (AH) and tibialis anterior (TA) with needle electrodes. Reproducible MEPs were obtained throughout the operation in all 20 cases, with up to 80 mA per stimulator. Before insertion of pedicle screws, mean MEP amplitudes (SD) obtained were 85 (19) and 21.7 (10.8) mV for AH and TA, respectively, using desflurane. With TIVA, amplitudes were 56.7 (28.4) and 59.1 (24.5) mV, respectively. Both muscle MEP amplitudes were significantly different using different anesthetic regimens (P < 0.05 for all). AH MEP amplitudes obtained with desflurane were significantly larger than TA amplitudes (P < 0.0001). No complications were reported intraoperatively and postoperatively. This is the first study comparing the use of desflurane and TIVA showing that both anesthetic regimens allowed successful intraoperative monitoring useage throughout the procedures. For MEP recording, the AH was the preferred muscle with a desflurane anesthetic regimen.

The laryngeal mask airway for awake craniotomy in the pediatric patient: report of three cases

The anesthetic management of three pediatric patients who underwent awake craniotomy with a combined, continuous intravenous infusion of propofol and alfentanil is described. The Laryngeal Mask Airway was effective in airway management during resection of epileptic foci with intraoperative cortical mapping and neuropsychological (speech) evaluation.

Facilitated Assessment of Unconsciousness from Morphologic Changes in the Bilateral Posterior Tibial Nerve Cortical Somatosensory Evoked Potential Under Total Intravenous Propofol Anesthesia During Spine Surgery

To describe a unique morphologic feature of the bilateral posterior tibial nerve cortical somatosensory evoked potential, the S-wave, which varies systematically with propofol infusion rate and which appears to be useful in guiding adequate propofol concentration levels during spine surgery. Two illustrative cases were selected from a pool of 15,000 pediatric and adult patients (ages 8-85 years) who were undergoing corrective spine surgery in operating rooms of university and community hospitals. Anesthesia was maintained with a continuous intravenous infusion of propofol (125-225 microg/kg/min) along with intermittent boluses of narcotic and midazolam (1.0-2.0 mg) as needed. Characteristic metamorphosis of the bilateral posterior tibial nerve cortical somatosensory evoked potential, highlighted by the emergence of an additional middle-latency component labeled the S-wave, served as a neurophysiological marker of "light" propofol anesthesia prompting elevation of propofol infusion rate or bolus injection. The S-wave was routinely abolished with increased propofol infusion rate or bolus injection. In all instances increased propofol concentration levels produced a characteristic morphologic change in the posterior tibial nerve cortical somatosensory evoked potential consistent with a return to adequate anesthetic depth. Selected cases presented herein compare the S-wave technique to BIS and illustrate the usefulness of the S-wave in identifying inadequate depth of propofol anesthesia. The bilateral posterior tibial nerve cortical somatosensory evoked potential changes its morphology in predictable fashion with decreased depth of propofol anesthesia, allowing for anticipation of imminent anesthetic "lightening." It serves as a useful cross-check to Bispectral Index (BIS) or other "level of consciousness" EEG-based algorithms for monitoring depth of propofol anesthesia during prolonged corrective spine surgery.

Combined Effects of Nitrous Oxide and Propofol on the Dynamic Cerebrovascular Response to Step Changes in End-tidal Pco2in Humans

Nitrous oxide (N2O) and propofol exhibit directionally opposite effects on the cerebral circulation, vasodilation and vasoconstriction, respectively. The authors investigated an interaction between the two anesthetic agents on the dynamic cerebrovascular response to step changes in end-tidal pressure of carbon dioxide (PetCO2) in humans. Participants with no systemic diseases were allocated into two groups, each of which was anesthetized sequentially with two protocols. Patients in group 1 were anesthetized with 30% O2 + 70% N2O. A continuous intravenous infusion of propofol (7-10 mg x kg(-1) x h(-1)) was then added to the N2O. Patients in group 2 were anesthetized first with continuous infusion of propofol (10 mg x kg(-1) h(-1)), and then 30% O2 + 70% N2O was added to the propofol anesthesia. Using transcranial Doppler ultrasonography, blood flow velocity at the middle cerebral artery (FV(MCA)) was measured during a step increase (on-response) followed by a step decrease (off-response) in PetCO2, with PetCO2 ranging between approximately 28 and 50 mmHg. The dynamic FV(MCA)-PetCO2 relationship was analyzed using a mathematical model that was characterized with a pure time delay, and a time constant and a gain each for the on- or off-response. The addition of propofol to the N2O anesthesia increased the on-response time constant (P < 0.01), whereas the addition of N2O to the propofol anesthesia increased the time constants for on- (P < 0.01) and off-responses (P < 0.05). However, the addition of either anesthetic did not affect the gains. Propofol and N2O, when one is added to the other, produce similar dynamic FV(MCA) responses to sudden changes in PetCO2. Addition of each anesthetic slows the dynamic response and produces the response whose magnitude is proportional to the baseline FV(MCA).

The relationship of muscle perfusion and metabolism with cardiovascular variables before and after detomidine injection during propofol–ketamine anaesthesia in horses

ObjectivesTo study in horses (1) the relationship between cardiovascular variables and muscle perfusion during propofol–ketamine anaesthesia, (2) the physiological effects of a single intravenous (IV) detomidine injection, (3) the metabolic response of muscle to anaesthesia, and (4) the effects of propofol–ketamine infusion on respiratory function. Study designProspective experimental study. AnimalsSeven standardbred trotters, 5–12 years old, 416–581 kg. MethodsAnaesthesia was induced with intravenous (IV) guaifenesin and propofol (2 mg kg−1) and maintained with a continuous IV infusion of propofol (0.15 mg kg−1 minute−1) and ketamine (0.05 mg kg−1 minute−1) with horses positioned in left lateral recumbency. After 1 hour, detomidine (0.01 mg kg−1) was administered IV and 40–50 minutes later anaesthesia was discontinued. Cardiovascular and respiratory variables (heart rate, cardiac output, systemic and pulmonary artery blood pressures, respiratory rate, tidal volume, and inspiratory and expiratory O2 and CO2) and muscle temperature were measured at pre-determined times. Peripheral perfusion was measured continuously in the gluteal muscles and skin using laser Doppler flowmetry (LDF). Muscle biopsy samples from the left and right gluteal muscles were analysed for glycogen, creatine phosphate, creatine, adenine nucleotides, inosine monophosphate and lactate. Arterial blood was analysed for PO2, PCO2, pH, oxygen saturation and HCO3. Mixed venous blood was analysed for PO2, PCO2, pH, oxygen saturation, HCO3, cortisol, lactate, uric acid, hypoxanthine, xanthine, creatine kinase, creatinine, aspartate aminotransferase, electrolytes, total protein, haemoglobin, haematocrit and white blood cell count. ResultsCirculatory function was preserved during propofol–ketamine anaesthesia. Detomidine caused profound hypertension and bradycardia and decreased cardiac output and muscle perfusion. Ten minutes after detomidine injection muscle perfusion had recovered to pre-injection levels, although heart rate and cardiac output had not. No difference in indices of muscle metabolism was found between dependent and independent muscles. Anaerobic muscle metabolism, indicated by decreased muscle and creatine phosphate levels was evident after anaesthesia. ConclusionMuscle perfusion was closely related to cardiac output but not arterial blood pressure. Total intravenous anaesthesia with propofol–ketamine deserves further study despite its respiratory depression effects, as the combination preserves cardiovascular function. Decreases in high-energy phosphate stores during recovery show that muscle is vulnerable after anaesthesia. Continued research is required to clarify the course of muscle metabolic events during recovery.