Effect of butorphanol,midazolam or ketamine on romifidine based sedation in horses during standing cheek tooth removal

Background

Standing surgery, especially dental procedures, are commonly performed in horses. This leads to an increasing demand for reliable sedation protocols. Therefore, it was the purpose of this study to investigate the influence of butorphanol, midazolam or ketamine on romifidine based sedation in horses during cheek tooth removal.

Methods

Forty horses presented for tooth extraction were divided in four groups using matched pair randomization. Group R was sedated with romifidine (bolus 0.03 mg/kg, followed by a constant rate infusion (CRI) 0.05 mg/kg/h) and group RB with romifidine (same dose) and butorphanol (0.02 mg/kg; CRI 0.04 mg/kg/h). Group RM received romifidine (same dose) and midazolam (0.02 mg/kg; CRI 0.06 mg/kg/h) whereas group RK was administered romifidine (same dose) and ketamine (0.5 mg/kg; CRI 1.2 mg/kg/h). If sedation was not adequate a top up bolus of romifidine (0.01 mg/kg) was administered. The quality of sedation and the conditions for tooth extraction, the level of ataxia, chewing, head and tongue movement were evaluated by using a scoring system. The investigator was blinded to the applied sedation protocol. Furthermore, serum cortisol concentrations before, during and after the procedure were analyzed to gain more information about the stress level of the horses.

Results

Horses in group RM showed significantly less chewing and tongue activity compared to horses sedated with romifidine alone or with butorphanol additionally, but also significantly higher levels of ataxia. The quality of sedation was significantly better if romifidine was administered in combination with ketamine compared to romifidine alone. Furthermore, horses of group RK needed less additional romifidine boli compared to all other groups. Blood cortisol concentrations during surgery in groups RB and RM remained unchanged. Horses of group R showed higher cortisol concentrations during sedation compared to horses of groups RB and RM.

Conclusion

Romifidine alone at an initial bolus dose of 0.03 mg/kg followed by a constant rate infusion of 0.05 mg/kg/h was insufficient to obtain an adequate level of sedation and led to increased stress levels, whereas the addition of butorphanol inhibited the stress response. The combination of romifidine with either midazolam or ketamine improved sedation quality and surgical conditions.

     

Consequences of concurrent Ascaridia galli and Escherichia coli infections in chickens

   

The principal aim of this study was to evaluate dissociative anaesthesia for castration of colts during field conditions. Three dissociative anaesthetic protocols were evaluated during castration of colts in an animal hospital. The protocol considered to be the most suitable was thereafter evaluated during castration of colts under field conditions. Respiratory and haemodynamic parameters and the response to surgery were determined during anaesthesia. All horses breathed air spontaneously during anaesthesia. Under hospital conditions 26 colts were randomised to receive one of three anaesthetic protocols: Romifidine and tiletamine-zolazepam (RZ); acepromazine, romifidine and tiletamine-zolazepam (ARZ); or acepromazine, romifidine, butorphanol and tiletamine-zolazepam (ARBZ). The surgeon was blinded to the anaesthetic protocol used and decided whether supplemental anaesthesia was needed to complete surgery. Under field conditions 31 colts were castrated during anaesthesia with the ARBZ protocol. All inductions, anaesthesia and recoveries were calm and without excitation under both hospital and field conditions. Surgery was performed within 5–20 minutes after the horses had assumed lateral recumbency during both hospital and field castrations. Under hospital conditions some horses needed supplemental anaesthesia with all three anaesthetic protocols to complete surgery. Interestingly, none of the horses castrated with protocol ARBZ under field conditions needed additional anaesthesia. Cardiorespiratory changes were within acceptable limits in these clinically healthy colts.     

A Novel and Effective Balanced Intravenous-Inhalant Anaesthetic Protocol in Swine by Using Unrestricted Drugs

Nowadays, because of increasing employment of swine for experimental studies and medical training, it is hopeful to investigate novel and effective anaesthetic protocols for preserving the animal welfare in medical investigation and concurrently improving the quality of research. Therefore, the aim of this study was to investigate a novel and effective anaesthetic protocol in swine undergoing major surgery, by translating know-how of combined anaesthesia from human protocols. Seven landrace swine were anaesthetized for three hours by a combined trial anaesthetic protocol (sedation: medetomidine, acepromazine, atropine and tramadol; induction: propofol, medetomidine and acepromazine; anaesthesia: isofluorane, propofol, medetomidine and acepromazine) and both clinical and haemodynamic parameters were compared with those of five swine anaesthetized with a control protocol (sedation: diazepam, ketamine and atropina; induction: diazepam and ketamine; anaesthesia: isofluorane). Both cardiac frequency (CF) and mean blood pressure (MBP) were significantly (P<0.05) more stable in trial protocol (CF: 78.3 ± 4.6-81.1 ± 5, MBP: 63.9 ± 10.7-96.4 ± 13.0) compared to control protocol (CF: 93.7 ± 5.5-102.5 ± 8.5, MBP: 71.0 ± 6.6-108.7 ± 7.2). The body temperature remained stable in trial protocol (°C: 36.9 ± 0.7-37.2 ± 0.3) compared to control anaesthesia (°C: 36.4 ± 0.3-37.3 ± 0.2, P<0.05). Haematosis improved undergoing combined anaesthesia (+2%, P<0.05) whereas did not change in control animals. There were no differences in respiratory rate between trial and control protocols. This study demonstrates that the proposed balanced intravenous-inhalant protocol permits to carry out a very effective, stable and safe anaesthesia in swine undergoing deep anaesthesia.     

A comparison of ketamine/xylazine and ketamine/xylazine/acepromazine anesthesia in the rabbit

Parenteral anesthetic combinations such as ketamine and xylazine have become the agents of choice for anesthesia in the rabbit, because they are effective, easily administered and inexpensive. A number of recent reports have recommended including acepromazine in this combination, but a critical evaluation of this combination in the rabbit has not been reported. Five adult New Zealand white rabbits were anesthetized intramuscularly with ketamine (35 mg/kg) and xylazine (5 mg/kg) with or without acepromazine (0.75 mg/kg). The study was conducted in a double blind fashion, where each rabbit was administered both combinations at a minimum of 7 day intervals. Physiologic parameters were evaluated including heart rate, respiratory rate, central arterial blood pressure, pedal, palpebral and postural reflex activity. The duration of general anesthesia, estimated by the time elapsed between the loss and return of the palpebral reflex, was greater (means = 99 +/- 20 minutes) when acepromazine was employed in the combination compared to (means = 77 +/- 5 minutes) when ketamine/xylazine were used alone. Mean central arterial blood pressure reached a lower level when acepromazine was utilized (means = 46 +/- 8 mm/Hg) than when it was not (means = 57 +/- 12 mm/Hg.). The addition of acepromazine in a ketamine/xylazine combination resulted in a 28% longer period of anesthesia, a 19% lower mean central arterial blood pressure and a 32% longer recovery of postural reflexes. The ketamine/xylazine/acepromazine combination is a useful regimen for normovolemic animals when anesthetic duration greater than that produced by ketamine/xylazine alone is required.     

Abnormal motor activity during anaesthesia in a dog: a case report

Seizures or convulsions that occur during anaesthesia in veterinary patients are infrequently reported in the literature. Consequently, the incidence of such events is unknown. Several drugs commonly used in clinical veterinary anaesthesia have been shown to induce epileptiform activity in both human clinical patients and experimental candidates. The present case report describes convulsions in a four-year old male Bernese mountain dog during maintenance of anaesthesia with isoflurane after premedication with acepromazine and methadone followed by co-induction with propofol and ketamine. The dog had no history of previous convulsions. The use of several sedative and anaesthetic drugs makes it difficult to find one single causative pharmaceutical.     

Effect of midazolam and butorphanol premedication on inhalant isoflurane anesthesia in mice

Isoflurane is a representative inhalant anesthesia used in laboratory animals. However, isoflurane mediates respiratory depression and adverse clinical reactions during induction. In the present study, we established a novel balanced anesthesia method in mice that combined isoflurane anesthesia with midazolam and butorphanol (MB). Thirty-four male C57BL/6J mice received either isoflurane alone or isoflurane with an intra-peritoneal MB premedication (3 mg/kg midazolam and 4 mg/kg butorphanol). The minimum alveolar concentration (MAC) in each group was evaluated. Induction time and adverse clinical reactions were recorded in each group. Core body temperature, heart rate, respiratory rate, and oxygen saturation (SPO₂) were assessed before and for 1 h after induction. Premedication with MB achieved a significant reduction in MAC compared with isoflurane monoanesthesia (isoflurane, 1.38 ± 0.15%; isoflurane with MB, 0.78 ± 0.10%; P<0.05). Induction time was significantly shortened with MB premedication, and adverse reactions such as excitement or incontinence were observed less frequently. Furthermore, isoflurane anesthesia with MB premedication caused increase of respiratory rates compared to isoflurane monoanesthesia. No significant decrease of SPO₂ was observed in MBI anesthesia, while a decrease in SPO₂ was apparent with isoflurane monoanesthesia (baseline, 98.3% ± 1.1; 10 min after induction, 91.8 ± 6.4%; P<0.05). In conclusion, premedication with MB was effective for the mitigation of respiratory depression induced by isoflurane in mice, with rapid induction and fewer adverse clinical reactions.     

Interrelations among children,parents, premedication,and anaesthetists in paediatric day stay surgery.

OBJECTIVE--To investigate the incidence of difficulties associated with parental presence during the induction of anaesthesia in children and the influence of premedication with special reference to vomiting after papaveretum. DESIGN--Mixed factual and multiple choice questionnaire completed by medical and nursing staff and parents during and after admission. SETTING--Teaching hospital with regional paediatric general surgical unit where parental presence during induction of anaesthesia is long established. PATIENTS--151 Children aged 1-14 years who had not previously undergone surgery attending with parents for day stay general surgical procedures. INTERVENTION--Children were randomly allocated to receive no premedication (group 1), oral diazepam elixir (0.3 mg/kg) (group 2), or intramuscular papaveretum with hyoscine (0.3 mg/kg with 0.006 mg/kg) (group 3). No other modification to established day stay routine was made. RESULTS--No major problems were associated with the presence of parents during the induction of anaesthesia. Only 10 of the 141 parents who accompanied their child caused some difficulty, and five became distressed. Premedication with both diazepam and papaveretum resulted in sedation but did not ease induction of anaesthesia. Papaveretum greatly reduced pain and distress immediately after the operation, pain and discomfort being observed in only 15% of children (7/48) compared with 66% (27/41) in group 1 and 49% (22/45) in group 2. Papaveretum, however, must be given intramuscularly, and nurses observed that the children preferred being given premedication orally to intramuscularly. In addition, the incidences of nausea and vomiting were significantly higher in the postoperative ward and at home with papaveretum, although no patient who had been given the drug was nauseous or vomited in the recovery area. The incidences of nausea in group 3 were 62% (31/50) and 57% (27/47) in the postoperative ward and at home, respectively, v 21% (7/33) and 14% (4/29) in group 1 and 13% (5/38) and 14% (5/37) in group 2; the incidences of vomiting in group 3 were 60% and 43% in the postoperative ward and at home, respectively, v 18% and 7% in group 1 and 11% and 11% in group 2. Finally, neither the administration or otherwise of premedication nor the drug given affected the children''s or parents'' perception of day care surgery. CONCLUSIONS--Difficulties with parents in anaesthetic rooms were not common or severe. Premedication provides preoperative sedation and papaveretum improves the immediate postoperative course but the incidences of nausea and vomiting after operation are higher with its use than without.     

Ketamine/xylazine/butorphanol: a new anesthetic combination for rabbits.

Ketamine is often used in combination with tranquilizers to produce surgical anesthesia in rabbits. While generally effective, there is considerable variation in the depth and duration of anesthesia achieved with ketamine combinations. Butorphanol is a mixed agonist-antagonist opioid that is widely used in a variety of other species. In this study, the commonly used ketamine (35 mg/kg)/xylazine (5 mg/kg) combination is compared with ketamine (35 mg/kg)/xylazine (5 mg/kg)/butorphanol (0.1 mg/kg). Rabbits were anesthetized on consecutive weeks with one of the two regimens. Physiologic parameters including heart rate, respiratory rate, blood pressure and arterial blood gases (pH, PO2, PCO2) were measured throughout anesthesia. Loss of palpebral, pedal and righting reflexes were recorded and reflexes were subsequently evaluated. The addition of butorphanol prolonged reflex loss to 140% (X = 68 min +/- 20 SEM) of control for palpebral reflex; 506% (X = 52 min +/- 18 SEM) of control for pedal reflex; and 159% (X = 128 min +/- 21 SEM) of control for righting reflex. Addition of butorphanol to ketamine/xylazine resulted in mild alterations in the physiologic changes traditionally associated with this combination. Butorphanol can be safely added to the ketamine/xylazine combination in rabbits and results in moderate increases in the duration of reflex loss.     

Four methods for general anaesthesia in the rabbit: a comparative study

The efficacy and safety of pentobarbitone, ketamine/xylazine, fentanyl/fluanisone/diazepam, and halothane/nitrous oxide anaesthesia were compared in 4 groups of six New Zealand White rabbits. Heart and respiratory rates, body temperature, reflexes, blood pressure and blood gases were measured. Pentobarbitone appeared to be unsuitable for anaesthesia in rabbits, as 5 of the 6 rabbits to whom it was administered, required artificial respiration or died. The combinations of ketamine/xylazine and fentanyl-fluanisone/diazepam both produced unpredictable levels of anaesthesia together with a substantial decline in arterial blood pressure and PO2. Despite a severe drop in blood pressure (up to 37.5%), anaesthesia with halothane and nitrous oxide was found to be superior to the other anaesthetic agents.     

Effect of Diazepam on Awareness during Caesarean Section under General Anaesthesia

The use of diazepam for premedication before elective caesarean section increased the incidence of unpleasant recall postoperatively, compared with atropine in a previous study. This finding suggests that diazepam is unsuitable for this type of anaesthesia.     

Physiologic and electrocardiographic responses of American river otters (Lutra canadensis) during chemical immobilization and inhalation anesthesia

Rectal temperatures and heart rates of American river otters (Lutra canadensis) decreased significantly (P less than 0.05) during chemical immobilization with i.m. ketamine hydrochloride in combination with xylazine hydrochloride and acepromazine and during inhalation anesthesia with isoflurane. Anesthetized otters showed a tendency for apnea during induction and while dorsally recumbent, which was reflected by a respiratory acidosis on arterial blood gases. Declines in rectal temperatures and heart rates were not found to be a function of dosage (mg/kg) of the ketamine combination used except for rectal temperatures of otters in relatively poor body condition (inanition). The electrocardiograms of isoflurane-anesthetized otters were similar to those recorded on immobilized otters with the exception of an r' deflection in the ventricular depolarization complex (RSr'). Electrocardiographic criteria were not found which predicted the degree of right ventricular or generalized cardiac enlargement seen radiographically.     

The effects of prolonged ketamine-xylazine intravenous infusion on arterial blood pH, blood gases, mean arterial blood pressure, heart and respiratory rates, rectal temperature and reflexes in the rabbit

The prolonged and safe maintenance of general anesthesia in rabbits with commonly used injectable agents is difficult. Protracted, stable anesthesia with short recovery time has been described in humans using continuous intravenous infusion of ketamine with or without sedatives, muscle relaxants and paralytics. This study evaluated the anesthetic plane achieved and respiratory and cardiovascular effects produced with a ketamine-xylazine intravenous infusion in New Zealand White rabbits. Ten female rabbits were anesthetized with intramuscularly administered ketamine hydrochloride (35 mg/kg) and xylazine hydrochloride (5 mg/kg) after the preanesthetic, baseline measurements of arterial blood pO2, pCO2 and pH and heart and respiratory rates were recorded. The above parameters as well as mean arterial blood pressure, righting, palpebral, pedal, and jaw reflexes were monitored ten minutes after the intramuscularly administered dosage and throughout 4 hours of infusion. Results showed moderate hypotension (21.2% deviation from normal, p less than 0.008) and profound hypoxemia (45% deviation from baseline, p less than 0.001) 10 minutes after the intramuscularly administered induction dosage. Then, the 4 hour infusion of ketamine (1 mg/minute) and xylazine (0.1 mg/minute) was started. Hypotension progressed (49.1% deviation from normal, p less than 0.008), but hypoxemia and hypercarbemia gradually improved with no resultant change (p greater than 0.1) in arterial pH. There was no significant change (p greater than 0.1) in respiratory rate but varying qualities of respiration were observed. Both mean arterial pO2 and pCO2 values returned to baseline within 20 minutes after completion of infusion. Heart rate and rectal temperature remained stable during the trial. The righting reflex was abolished in all rabbits throughout the study.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pentobarbital versus medetomidine-ketamine-fentanyl anaesthesia: effects on haemodynamics and the incidence of ischaemia-induced ventricular fibrillation in swine

The present study was performed to compare haemodynamic variables at baseline and the incidence of ventricular fibrillation during the early phase of ischaemia in swine during pentobarbital or medetomidine-ketamine-fentanyl anaesthesia. Twenty-two swine (mean +/- SD: 29+/- 3 kg) were anaesthetized with sodium pentobarbital (induction with 36 mg/kg intraperitoneally, and maintenance with 5-20 mg/kg/h intravenously [i.v.]) and 6 swine (27+/- 3 kg) were anaesthetized with ketamine and fentanyl (premedicated with medetomidine 0.1 mg/kg and ketamine 10 mg/kg intramuscularly, induction with ketamine 20 mg/kg and fentanyl 0.025 mg/kg i.v., and maintenance with ketamine 20 mg/kg/h and fentanyl 0.025 mg/kg/h i.v.). After a stabilization period of 30 min, the left anterior descending coronary artery (LAD) was occluded for 10 min. Haemodynamic data and occurrence of ventricular fibrillation were recorded. The ischaemic area was measured by fluorescing microspheres. Swine anaesthetized with medetomidine-ketamine-fentanyl had significantly lower heart rate, myocardial contractility, peak left ventricular pressure, arterial blood pressure, aortic blood flow, myocardial blood flow and cardiac index at baseline, than swine anaesthetized with pentobarbital. Whereas none of the swine anaesthetized with pentobarbital fibrillated during the LAD occlusion, ventricular fibrillation occurred in 83% of the animals anaesthetized with medetomidine-ketamine-fentanyl (P< 0.001). No significant difference was found in size of ischaemic area between the two groups. Thus, we show a depression in haemodynamic variables at baseline and a higher incidence of ventricular fibrillation during the early phase of ischaemia in swine anaesthetized with medetomidine-ketamine-fentanyl compared to swine anaesthetized with pentobarbital.     

Guaiphenesin-ketamine-xylazine infusion to maintain anesthesia in mules undergoing field castration

Background

In order to determine whether a combination of guaiphenesin, ketamine and xylazine can induce safe and satisfactory anaesthesia in mules undergoing field castration, eight healthy adult intact male mules were employed. They were premedicated with intravenous (IV) xylazine (1.3 mg/kg); an additional dose of xylazine (0.3 mg/kg IV) was administered in case of inadequate depth of sedation. Anaesthesia was induced with IV thiopental (6 mg/kg). The quality of sedation and induction was recorded. Anaesthesia was maintained with an infusion of guaiphenesin (50 mg/mL), ketamine (2 mg/mL) and xylazine (1 mg/mL) (GKX). The spermatic cord of each testis was infiltrated with 5 mL of 2% lidocaine. During anaesthesia heart rate (HR), respiratory rate (RR), rectal temperature (RT) and haemoglobin oxygen saturation (SpO₂) were measured every 5 min. The data were analysed with simple one-way analysis of variance (ANOVA). A P value < 0.05 was considered statistically significant. Time of anesthesia, time of surgery and time of recovery were recorded.

Results

Only one mule required an additional dose of xylazine to achieve a satisfactory depth of sedation. Thiopental at the dose of 6 mg/kg IV resulted in smooth induction and lateral recumbency in all animals. GKX provided adequate anaesthesia to perform castration in all mules. Muscle relaxation was deemed adequate and physiological variables remained stable and within references values during the anaesthesia and did not change in response to surgical stimulation. Time (mean ± standard deviation) from the end of the infusion to sternal recumbency and time from sternal recumbency to standing were 27.7 ± 4.6 and 30.1 ± 7.7 min, respectively.

Conclusions

The combination of xylazine, thiopental and GKX provides satisfactory short-term anaesthesia in mules undergoing field castration.

     

Intravenous Diazepam for Direct-current Cardioversion

The induction of anaesthesia with intravenous diazepam is a valuable contribution to the simpler use of cardioversion and is the method of choice because it is readily available for elective cardioversion. Fifty-six cardioversion procedures were carried out by this method in an African hospital. No special premedication or drug preparation was used. There were no hazards apart from transient apnoea in two patients and persisting amnesia in one patient.     

Sufentanil and medetomidine anaesthesia in the rat and its reversal with atipamezole and butorphanol

Injectable anaesthetics are widely used to anaesthetize rats, but recovery times are often prolonged. Reversible anaesthetic regimens have the advantage that animals may be recovered quickly, thus reducing the incidence of postoperative complications such as hypothermia, and also providing a means of treating inadvertent anaesthetic overdose. This study assessed and compared the characteristics of anaesthesia induced with combinations of sufentanil and medetomidine administered as a single subcutaneous or intraperitoneal dose, and reversal with butorphanol and atipamezole. Combinations of sufentanil/medetomidine at 40 microg/150 microg and 50 microg/150 microg/kg administered subcutaneously, and 80 microg/300 microg/kg by intraperitoneal injection were found to produce surgical anaesthesia for 101+/-49, 124+/-45 and 76+/-23 min (means +/- SD) respectively. All three combinations produced marked respiratory depression 30 min after injection (< 50% of resting respiratory rate). Oxygen saturation, measured by pulse oximetry, was < 50% in all groups 30 min following drug administration. Subcutaneous administration is recommended since it resulted in a more reliable and more rapid induction of anaesthesia than intraperitoneal administration. The administration of butorphanol and atipamezole (0.2/0.5 mg/kg s.c.) resulted in a rapid (< 7 min) reversal of anaesthesia and an associated respiratory depression. The induction of anaesthesia with sufentanil/medetomidine and its reversal with a combination of atipamezole and butorphanol is an effective technique for anaesthetizing rats. However, due to the marked respiratory depression and the resulting hypoxia, we recommend that this regimen should only be used in animals which are free from respiratory disease and that oxygen should be provided during anaesthesia.     

Cardiopulmonary effects of nalbuphine hydrochloride and butorphanol tartrate in sheep

The cardiopulmonary, sedative and analgesic effects of butorphanol tartrate and nalbuphine hydrochloride were evaluated in six adult crossbred Dorset sheep (Ovis aries). The animals were divided randomly into two groups of three. The first group received butorphanol tartrate (0.5mg/Kg s.c.) followed in 3 days by nalbuphine hydrochloride (1 mg/Kg, s.c.). The second group received nalbuphine followed in 3 days by butorphanol. Cardiopulmonary parameters were evaluated at baseline (once the animal had accommodated to restraint); immediately following analgesic administration; and at 15, 30, 60, 90 and 120 minutes after analgesic administration. No significant changes (alpha greater than .05) from baseline were seen in any of the measured cardiopulmonary parameters from either the butorphanol or nalbuphine groups. Butorphanol produced the most dramatic analgesic and sedative effects with onset of both within 15 minutes of administration and peak effects occurring 30 minutes post injection. The degree of analgesia was diminished at 120 minutes while the sedative effect returned to near baseline by 90 minutes. The nalbuphine group also showed an onset of analgesia 15 minutes post injection reaching a peak effect after 30 minutes. However, onset of sedation occurred 30 minutes post injection achieving a peak effect at 60 minutes which was markedly less than that of butorphanol. As in the butorphanol group, analgesia was diminished at 120 minutes.     

Anaesthesia and the acute phase protein response in children undergoing circumcision

Concentrations of acute phase proteins (CRP: C-reactive protein, albumin) change during surgery. We investigated the acute phase response to circumcision and the effects of anaesthesia on this response. The children were divided into four groups; group 1 (intratracheal general anaesthesia, n=40), group 2 (general anaesthesia with mask, n=20), group 3 (ketamine, n=20), group 4 (local anaesthesia, n=35). Blood samples were obtained, 24 hours before circumcision, after premedication, and 24 hours after circumcision. CRP and albumin before circumcision were comparable for all groups. There was no increase in CRP, and albumin remained steady throughout the study. No difference was observed among the groups, and related to anaesthesia. No responsiveness may be explained with the size of injured tissue or anatomical and histological type of preputium.     

Cutaneous and subcutaneous blood flow during general anaesthesia

The vasodilator effect of anaesthetic agents on cutaneous vessels has often been investigated. In contrast, although subcutaneous tissue is concerned with metabolism and thermoregulation, the effects of anaesthesia on subcutaneous blood flow have not been well documented. The purpose of this study was to determine the magnitude of changes in cutaneous and subcutaneous blood flow during general anaesthesia in Man. Anaesthesia was induced with flunitrazepam in 15 patients before facial plastic surgery. Blood flow was estimated using heat thermal clearance (HC). Two HC sensors in different areas allowed the measurement of superficial and deep HC. Systolic (SABP), diastolic (DABP) and mean arterial blood pressure (MABP), heart rate (HR), and rectal and mean skin temperature were also recorded. After induction of anaesthesia, HR increased significantly (p less than 0.05) whereas SABP, DABP and MABP remained unchanged. The rectal-toe temperature gradient fell from 6.3 +/- 4.1 degrees C to 3.4 +/- 1.1 degrees C (p less than 0.01) suggesting a reduction in vasomotor tone. Superficial HC increased from 0.37 +/- 0.06 to 0.42 +/- 0.08 W.m-1.degrees C-1 (p less than 0.05) whereas deep HC decreased from 0.33 +/- 0.07 to 0.31 +/- 0.09 W.m-1.degrees C-1 (NS) and returned to the control value thereafter. Rectal temperature and mean skin temperature were unchanged. The changes in deep HC are similar to those previously observed in muscle during induction of anaesthesia. Our results show that anaesthesia mainly affects cutaneous blood flow, without any significant change in subcutaneous blood flow during the early phase of anaesthesia in human beings.     

Cardiovascular responses to V1-vasopressinergic antagonism in conscious versus anesthetized rats

Experiments were performed to compare the possible effect of endogenous arginine vasopressin on renal hemodynamics between anesthetized, surgically stressed rats and conscious rats. Animals were instrumented with arterial and venous catheters as well as with a pulsed Doppler flow probe on the left renal artery. The rats were studied under the following conditions: (1) conscious and unrestrained; (2) anesthetized only; (3) anesthetized with minor surgical stress; and (4) anesthetized with major surgical stress. Two anesthetic agents were also compared, a mixture of ketamine (110 mg/kg i.m.) and acepromazine (1 mg/kg i.m.), and sodium pentobarbital (50 mg/kg i.p.). Baseline mean arterial blood pressure was significantly higher in pentobarbital-anesthetized rats following surgical stress compared with conscious animals, but blood pressure was not affected by ketamine-acepromazine anesthesia. After baseline measurements of blood pressure, heart rate, and renal blood flow, a specific V1-vasopressinergic antagonist (d(CH2)5Tyr(Me) arginine vasopressin, 10 mg/kg i.v.) was administered to each group. Mean arterial blood pressure, heart rate, and renal blood flow were monitored for an additional 15 min. Mean arterial blood pressure and renal blood flow decreased after V1 antagonism in ketamine-acepromazine-anesthetized rats with major surgical stress, but were not affected in pentobarbital-anesthetized animals. Heart rate and renal vascular resistance were not affected following V1 blockade with either anesthetic agent. These data suggest that arginine vasopressin plays a role in maintaining blood pressure and renal perfusion in ketamine-acepromazine-anesthetized rats following surgical stress, but does not have a significant effect on renal hemodynamics under pentobarbital anesthesia.