Epidural vs general anaesthesia and leg blood flow in patients with occlusive atherosclerotic disease

Total leg blood flow (plethysmography), skin blood flow (laser-Doppler flowmetry), and haemodynamic stability (MAP, HR, RPP) were studied in vascular (ABI less than 1.0; n = 31) and in non-vascular (ABI greater than 1.0; n = 24) surgical patients during epidural or fentanyl-supplemented general anaesthesia. During epidural anaesthesia significant increases in total leg blood flow were observed in vascular (from 1.9 +/- 0.2 to about 3 ml/100 ml tissue/min) as well as in non-vascular (from 2.5 +/- 0.6 to about 7 ml/100 ml tissue/min) patients and leg blood flow remained high in the postanaesthetic period. During general anaesthesia total leg blood did not increase, either in vascular or in non-vascular patients, and in the postanaesthetic period blood flow values even lower than the initial ones were observed. Skin blood flow increased about 4-fold in vascular as well as in non-vascular patients following both types of anaesthesia. In the immediate postanaesthetic period low flow values were again observed but only in the general anaesthesia groups. In vascular patients no critical redistribution of blood flow within the limb was observed irrespective of the type of anaesthesia. Good haemodynamic stability could only be maintained in the epidural group. It is concluded that epidural anaesthesia seems to offer considerable advantages over general anaesthesia for high-risk vascular patients during arterial reconstructions since better haemodynamic stability and higher leg blood flow can be achieved.     

Effects of epidural anaesthesia on microcirculatory blood flow in free flaps in patients under general anaesthesia

It has been suggested that epidural anaesthesia may increase blood flow in free flaps on the lower extremity. The objective of the present study was to test this hypothesis in 21 patients undergoing reconstructive surgery of the lower extremity with free muscle (n = 8), fasciocutaneous (n = 6) or musculocutaneous (n = 7) flaps. Microcirculatory blood flow was measured continuously with a multichannel laser Doppler flowmetry, both in muscle and skin of the free flap as well as in the intact skin and muscle on the same extremity. After completion of surgery, general anaesthesia was continued and the epidural block was induced by an injection of 2% lignocaine-hydrochloride into a pre-operatively inserted and tested epidural catheter. The epidural block caused no change in microcirculatory flow in the intact skin and muscle, however, it resulted in a marked decrease in microcirculatory blood flow in all the free flaps studied (20-30%; P < 0.05). The epidural block also caused a significant decrease in mean arterial blood pressure, from 85 (+/- 2.8) mmHg to 68 (+/- 2.8) mmHg (P < 0.01). It was concluded that epidural anaesthesia may decrease microcirculatory blood flow in free flaps on the lower extremity by diverting flow away from the flap to normal intact tissues (a steal phenomenon).     

Preoperative parental anxiety predicts behavioural and emotional responses to induction of anaesthesia in children

Parental presence at induction of anaesthesia is desirable if it makes the child happier and more cooperative. This study evaluated the emotional and behavioural responses of children to being accompanied by a parent at induction of anaesthesia in a paediatric day-care surgical centre. One hundred and thirty-four patients (aged 2-10 yr, ASA physical status I or II) were divided into two groups by day of surgery, to have a parent present at induction of anaesthesia (treatment group), or to be unaccompanied (control group). Before, and at one week after surgery, the child's fears and behaviour were scored by the Hospital Fears Inventory (HFI) and Behavioural Questionnaire (BQ), and parental anxiety by the Parents' Questionnaire (PQ) before and at one week after surgery. The Global Mood Scale (GMS) was used to assess the child's behaviour and the Visual Analogue Scale (VAS) to assess the parent's anxiety on arrival for surgery and at induction of anaesthesia. All patients and parents were disturbed by the experience, but to the same degree in the treatment and control groups. Subgroups of "calm" and "anxious" parents were identified by a median split of their preoperative VAS scores. Children in the "calm-treatment," "calm-control" and "anxious-control" subgroups were similarly upset at induction. Children in the "anxious-treatment" subgroup were the most disturbed at induction, and significantly more than those in the "anxious-control" subgroup. Preoperative parental anxiety levels also correlated with the child's fears and behaviour one week after surgery.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pharmacokinetics of sufentanil in general surgical patients under different conditions of anaesthesia

The pharmacokinetics of sufentanil were studied in 56 surgical patients after an intravenous bolus of 2 μg kg^-1, in association with neurolept analgesia or volatile anaesthetics (halothane, enflurane and isoflurane). Plasma concentrations of sufentanil were measured by radioimmunoassay. The kinetics of sufentanil were comparable under neurolept analgesia and under anaesthesia with halothane, enflurane or isoflurane. The overall mean elimination half-life was 182 min, Vd⁸⁵ 169 1 and the plasma clearance 910 ml min^-1. Except for the isoflurane subgroup, there was no significant correlation between half-life, the volume of distribution or clearance with age (24–77 years) or body weight (45–95 kg).     

The effects of preanesthetic oral clonidine upon heart rate response to intravenous atropine in patients during general anesthesia]

In awake subjects the positive chronotropic effect of intravenously administered atropine 10 micrograms.kg-1 has been demonstrated to be blunted by preanesthetic medication of oral clonidine 5 micrograms.kg-1. The aim of the present study is to investigate whether general anesthesia could alter the clonidine-induced attenuation of positive chronotropic effect by atropine. Thirty-two patients were randomly assigned to one of the two groups; patients of the clonidine group received oral clonidine 5 micrograms.kg-1 (n = 12), whereas those of the control group received no clonidine. General anesthesia was induced with intravenous thiamylal 4-5 mg.kg-1, and was maintained with enflurane and nitrous oxide in oxygen after endotracheal intubation. Following the stable circulatory period of 10 min, hemodynamic measurements were made at 1 min intervals for 10 min after atropine 10 micrograms.kg-1 was administered intravenously as a bolus in both groups. A significant attenuation in heart rate response to intravenous atropine 10 micrograms.kg-1 was observed in patients receiving clonidine 5 micrograms.kg-1, as compared with that in the control group (P less than 0.01); maximal increases in heart rate were 15 +/- 8 and 22 +/- 6 beats.min-1 (mean +/- SD) in the clonidine and control groups, respectively. It is concluded that clonidine 5 micrograms.kg-1 blunts the heart rate response to intravenous atropine 10 micrograms.kg-1 in patients anesthetized with enflurane and nitrous oxide in oxygen.     

Preoperative planning to prevent instability in total knee arthroplasty.

Several factors can lead to persistent instability after total knee arthroplasty, including bone and soft tissue loss, preexisting ligamentous laxity, and poor operative technique. Achieving stability should not be equated with making the knee extremely tight, without any natural laxity.     

Preoperative oral dextromethorphan attenuated tourniquet-induced arterial blood pressure and heart rate increases in knee cruciate ligament reconstruction patients under general anesthesia

The precise mechanism of tourniquet-induced arterial blood pressure increase is unknown. We determined the effect of preoperative oral dextromethorphan (DM) on arterial blood pressure and heart rate changes during tourniquet inflation in knee cruciate ligament reconstruction patients under general anesthesia. Patients in the DM group (n = 38) received oral DM 30 mg, and patients in the control group (n = 38) received oral placebo 2 h before the induction of anesthesia. Anesthesia was maintained with sevoflurane 2.0% and N(2)O in 33% oxygen, and the trachea was intubated until the end of surgery. Arterial blood pressure and heart rate were measured at 0, 30, and 60 min after the start of tourniquet inflation. Systolic arterial blood pressure and heart rate at 60 min in the control group were significantly more than those in the DM group (131.1 +/- 15.8 mm Hg versus 123.6 +/- 15.9 mm Hg [P < 0.05] and 74.1 +/- 11.3 bpm versus 67.8 +/- 8.5 bpm [P < 0.01], respectively). The percentage increase in systolic arterial blood pressure and heart rate in the DM group was also attenuated when compared with that in the control group (P < 0.05). In conclusion, preoperative oral DM 30 mg significantly attenuated arterial blood pressure and heart rate increases during tourniquet inflation under general anesthesia. IMPLICATIONS: We demonstrated that preoperative oral dextromethorphan 30 mg significantly attenuated arterial blood pressure and heart rate increases at 60 min during tourniquet inflation in patients undergoing knee cruciate ligament reconstruction under general anesthesia.     

Preoperative small-dose ketamine prevented tourniquet-induced arterial pressure increase in orthopedic patients under general anesthesia

The mechanism of tourniquet-induced arterial pressure increase is not known. We investigated the effect of preoperative ketamine on tourniquet-induced arterial pressure and heart rate changes in 85 patients undergoing knee surgery with a tourniquet under general anesthesia. Patients were randomly assigned into three groups; Large Ketamine (n = 28; ketamine 1.0 mg/kg), Small Ketamine (n = 28; ketamine 0.25 mg/kg), and Control (n = 29; normal saline) groups. Anesthesia was maintained with 1.5%-2.5% sevoflurane and 66% N(2)O in oxygen with endotracheal intubation. Ketamine or normal saline was given in a double-blinded fashion before skin incision and tourniquet inflation. Arterial pressure and heart rate were recorded every 10 min until 60 min after the start of tourniquet inflation and again after deflation. Arterial pressure and heart rate were compared among the three groups by using repeated-measures analysis of variance. In the Large and Small Ketamine groups, arterial pressure was not significantly changed, but in the Control group arterial pressure was significantly increased 40, 50, and 60 min after the start of tourniquet inflation (P < 0.05). Development of more than a 30% increase in systolic arterial pressure during tourniquet inflation was more frequent in the Control group than the other groups. The results show that preoperative IV ketamine, 0.25 mg/kg or more, significantly prevented tourniquet-induced systemic arterial pressure increase in patients under general anesthesia. IMPLICATIONS: Preoperative small-dose ketamine, IV, significantly prevented a systemic arterial pressure increase during prolonged tourniquet inflation in patients under general anesthesia.     

Pretreatment with oral clonidine attenuates cardiovascular responses to tracheal extubation in children

This study was designed to evaluate the effects of diazepam and clonidine orally given preoperatively on cardiovascular responses to tracheal extubation in children. Fifty children, ASA physical status I, aged 4-10 years, undergoing minor elective surgery (inguinal hernia, phimosis) received orally, in a randomized, double-blind manner, diazepam 0.4 mg.kg-1 or clonidine 4 microgram.kg-1 (n=25 of each). These drugs were administered 105 min before an inhalational induction of anaesthesia. The same standard general anaesthetic technique was employed throughout. The maximum changes in heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were less in patients who had received clonidine than in those who had received diazepam (HR, 12 vs 24; SBP, 14 vs 26; DBP, 9 vs 16; mean, P < 0.05). In conclusion, compared to diazepam given orally, pretreatment with oral clonidine attenuates haemodynamic changes associated with tracheal extubation in children.     

Preoperative clonidine blunts hyperadrenergic and hyperdynamic responses to prolonged tourniquet pressure during general anesthesia

Although the mechanism of tourniquet-induced hypertension is still unclear, plasma norepinephrine concentrations continuously increase in parallel to arterial blood pressure during tourniquet inflation. Clonidine attenuates hyperadrenergic and hyperdynamic responses. We investigated the effects of clonidine on prolonged tourniquet inflation. Twenty-nine patients scheduled for elective orthopedic surgery were randomly assigned to receive IV clonidine (3 microg/kg; n = 14) or placebo (n = 15) before tourniquet inflation of the lower limbs under general anesthesia in a double-blinded manner. Arterial blood pressure, heart rate, epinephrine, and norepinephrine plasma concentrations were measured before tourniquet inflation, 60 min after tourniquet inflation, just before tourniquet deflation, and 20 min after tourniquet deflation. Mean arterial blood pressure and norepinephrine plasma-concentrations were significantly lower in the Clonidine group compared with Control after 60 min tourniquet inflation (P = 0.016; P = 0.006). Immediately before deflation of the tourniquet, the difference for mean arterial pressure between groups was even more pronounced (P = 0.005). Twenty minutes after deflation mean arterial blood pressure in the Control group was still increased and significantly higher compared with the Clonidine group (P = 0.002). In conclusion, preoperative IV clonidine blunts hyperadrenergic and hyperdynamic responses resulting from prolonged tourniquet inflation under general anesthesia in ASA class I--II patients. IMPLICATIONS: Tourniquet inflation is associated with a continuous increase in arterial blood pressure and sympathetic outflow. This study shows that IV clonidine effectively blunts increases of both arterial blood pressure and plasma norepinephrine concentrations.     

Postoperative complaints after spinal and thiopentone-isoflurane anaesthesia in patients undergoing orthopaedic surgery Spinal versus general anaesthesia

Background. The present prospective study investigates the impact of a standardized technique of spinal and general anaesthesia on the incidence and consequences of postanaesthetic complaints dependent on age and sex of patients.
Methods. 433 orthopaedic patients underwent lower limb surgery in spinal (group 1) or general (group 2) anaesthesia. Spinal anaesthesia was performed with 0.5% hyperbaric bupivacaine using a 26-gauge Quincke needle. General anaesthesia was induced with i.v. injection of thiopentone, fentanyl and atracurium and maintained with 65% nitrous oxide and 1-1.5 Vol% isoflurane in oxygen. On postoperative day 4, patients were interviewed for onset and duration of postoperative complaints.
Results. The overall incidence of nausea/vomiting ( P =0.025) and sore throat ( P =0.001) was higher in group 2. In addition, nausea/vomiting was higher in patients between 20 and 60 years in group 2 compared with group 1. While the incidence of urinary dysfunction was higher in men after spinal ( P =0.04), nausea/vomiting was more frequent in women after general anaesthesia ( P =0.008). Analgetic requirements ( P =0.013), time of postoperative surveillance ( P =0.042) and frequency of treatment of postoperative complaints ( P =0.0001) was higher in group 2.
Conclusion. Spinal anaesthesia was associated with a lower incidence of postoperative complaints and treatments and a shorter surveillance compared to general anaesthesia. Specific complications related to spinal anaesthesia did not depend on age or sex and may allow for recommendation of this technique even in younger and female patients undergoing orthopaedic surgery.     

Remifentanil vs. fentanyl during interventional rigid bronchoscopy under general anaesthesia and spontaneous assisted ventilation.

The treatment of tracheo-bronchial diseases with rigid bronchoscopy requires general anaesthesia without tracheal intubation. Spontaneous assisted ventilation is a safe modality of ventilation. In this study the use of remifentanil and fentanyl is compared during rigid bronchoscopy with spontaneous assisted ventilation. Ninety high-risk patients received fentanyl or remifentanil with propofol for general anaesthesia. During the maintenance fentanyl was delivered at 6.1 +/- 4.6 micrograms kg-1 h-1 and remifentanil at 0.15 +/- 0.07 microgram kg-1 min-1. The same degree of intra-operative respiratory acidosis with similar good operating conditions resulted in both groups. Patients treated with remifentanil recovered more quickly compared with those in the fentanyl group (3.8 +/- 2 vs. 10.4 +/- 9.2 min, P < 0.001). In conclusion, the use of remifentanil during rigid bronchoscopy under general anaesthesia with spontaneous assisted ventilation is safe and assures good operating conditions. Moreover, remifentanil permits a more rapid recovery than fentanyl. The dose of remifentanil is higher than previously described for spontaneously breathing patients.     

Cell-mediated and humoral immune responses to total hip replacement under spinal or general anaesthesia

Regional anaesthesia has many advantages over general anaesthesia in hip surgery. When the effects of total hip replacement under spinal or general anaesthesia were compared in 22 patients, the only difference between the groups occurred in PHA-induced lymphocyte proliferative responses. In contrast, no differences between the groups were observed in leucocyte or differential counts, lymphocyte or subtype counts, most mitogen-induced lymphocyte proliferative responses, NK-cell activity, IgG, IgM or IgA production by unstimulated or PWM-stimulated lymphocytes, proliferative responses of control lymphocytes with 15% patient serum, or chemiluminescence values in phagocytosis of zymosan opsonized with patient serum. Thus, regional anaesthesia is indicated in total hip replacement for reasons other than the immune response.     

Effects of oral clonidine premedication and postoperative i.v. infusion on haemodynamic and adrenergic responses during recovery from anaesthesia

The effects of clonidine, a central alpha 2-adrenoreceptor agonist, on haemodynamic and catecholamine changes were assessed during emergence from anaesthesia, a period which is associated with increased sympathetic nervous discharge, hypertension and tachycardia. According to a double-blind randomized design, 32 patients received either clonidine, preoperatively given by oral route (3.5 micrograms.kg-1) and postoperatively by i.v. infusion (0.3 microgram.kg-1.h-1), or a placebo. Perioperative management was similar in both groups. Measurements were made in the recovery room, before starting clonidine or placebo infusions for evaluation of clonidine premedication, and then during infusion as follows: when core temperature reached 37 degrees C; then 2 h, and 6 h later. Prior to starting infusions, mean blood pressure (88 +/- 15 vs 103 +/- 14 mmHg) (11.7 +/- 2.0 vs 13.7 +/- 1.9 kPa), heart rate (67 +/- 8 vs 87 +/- 17 beats.min-1) and plasma norepinephrine levels (462 +/- 393 vs 615 +/- 361 pg.ml-1) were lower in the clonidine group. Only at the latest measurement (6 h after core temperature reached 37 degrees C) did clonidine elicit significant effects. The values during clonidine infusion compared to placebo were at this time: mean blood pressure (73 +/- 10 vs 86 +/- 13 mmHg) (9.7 +/- 1.3 vs 11.5 +/- 1.7 kPa), heart rate (71 +/- 6 vs 93 +/- 13 beats.min-1) and plasma norepinephrine levels (240 +/- 224 vs 451 +/- 111 pg.ml-1). Our results suggest that: 1) preoperative clonidine may improve the haemodynamic profile associated with anaesthetic discontinuation, but 2) i.v. infusion (0.3 microgram.kg-1.h-1) did not prolong this effect during the early postoperative period in the face of the sympathetic nervous discharge of recovery.     

Perioperative lower limb venous haemodynamics in patients under general anaesthesia

Background. This study prospectively determined the haemodynamicchanges in the lower limb venous circulation during and shortlyafter elective abdominal surgery, performed under general anaesthesia. Methods. Ten females, aged 36–65 yr, ASA I or II, undergoingtotal abdominal hysterectomy had their peak, mean and minimumvelocities, diameter, volume flow and venous pulsatility (peak–minimum/meanvelocity) measured in the left popliteal vein on recumbencywith duplex at: (i) baseline, (ii) 15 min after induction, (iii)during surgery, and (iv) in recovery 30 min after extubation.Anaesthesia was induced with fentanyl and propofol, paralysiswith vecuronium, maintenance with isoflurane in nitrous oxide66%, and analgesia with morphine. Results are presented as percentagedifference from baseline mean value. The Friedman and Wilcoxon_{[corrected^*]}tests were applied. Results. Mean velocity decreased by 23.6% during surgery andby 34.6% in recovery (P<0.05^*). Minimum velocity was decreasedby 56% during surgery and by 78% in recovery (P<0.05). Thevolume flow decreased by 26% during surgery, and by 54.4% inrecovery (P<0.001). Diameter and peak velocity changed littleat surgery and recovery (P>0.2). In contrast, the pulsatilityincreased by 30% on induction, 83% on surgery and 109% in recovery(P<0.05). Compared with baseline, haemodynamic changes oninduction were small (P>0.1^*). Conclusions. A significant decrease in the volume flow, meanand minimum velocities was noted during and immediately afterelective total abdominal hysterectomy under general anaesthesiain ASA I and II patients. Flow changes in early recovery mirroredor enhanced those noted intraoperatively. Despite venous flowattenuation, haemodynamic readjustments produced a significantand progressive enhancement of venous flow pulsatility duringthe course of the procedure.      

Exposure to anaesthetic trace gases during general anaesthesia: CobraPLA vs. LMA classic

Background: To prospectively investigate the performance, sealing capacity and operating room (OR) staff exposure to waste anaesthetic gases during the use of the Cobra perilaryngeal airway (CobraPLA) compared with the laryngeal mask airway classic (LMA). Methods: Sixty patients were randomly assigned to the CobraPLA or the LMA group. Insertion time, number of insertion attempts and airway leak pressures were assessed after induction of anaesthesia. Occupational exposure to nitrous oxide (N₂O) and Sevoflurane (SEV) was measured at the anaesthetists' breathing zone and the patients' mouth using a photoacoustic infrared spectrometer. Results: N₂O waste gas concentrations differed significantly in the anaesthetist's breathing zone (11.7±7.2 p.p.m. in CobraPLA vs. 4.1±4.3 p.p.m. in LMA, P=0.03), whereas no difference could be shown in SEV concentrations. Correct CobraPLA positioning was possible in 28 out of 30 patients (more than one attempt necessary in five patients). Correct positioning of the LMA classic was possible in all 30 patients (more than one attempt in three patients). Peak airway pressure was higher in the CobraPLA group (16±3 vs. 14±2 cmH₂O, P=0.01). The average leak pressure of the CobraPLA was 24±4 cmH₂O, compared with 20±4 cmH₂O of the LMA classic (P<0.001; all values means±SD). Conclusion: Despite higher airway seal pressures, the CobraPLA caused higher intraoperative N₂O trace concentrations in the anaesthetists' breathing zone.     

Efficacy of dexmedetomidine in suppressing cardiovascular and hormonal responses to general anaesthesia for caesarean delivery: a dose-response study

BackgroundPreoperative dexmedetomidine administration blunts haemodynamic and hormonal responses to tracheal intubation and reduces anaesthetic requirements. We hypothesized that dexmedetomidine would reduce the maternal haemodynamic and hormonal responses to elective caesarean delivery without harmful neonatal effects.MethodsAfter ethical approval, 68 parturients scheduled for elective caesarean delivery under general anaesthesia were randomly allocated to receive either placebo, or 0.2, 0.4 or 0.6 μg/kg/h intravenous dexmedetomidine (n = 17 per group) 20 min before induction. Anaesthesia was induced using a rapid-sequence technique with propofol and suxamethonium, and was maintained with 0.5–0.75 minimum alveolar concentration sevoflurane. Changes in maternal heart rate, mean blood pressure, minimum alveolar concentration sevoflurane, uterine tone, serum cortisol level, and Apgar scores, Neurologic Adaptive Capacity Scores and acid–base status were recorded.ResultsAfter induction, patients receiving dexmedetomidine had smaller increases in heart rate (P < 0.001) than those in the placebo group. Patients who received 0.4 and 0.6 μg/kg/h infusions of dexmedetomidine showed slower heart rates (?21.5% and ?36%, respectively; P < 0.001), lower mean blood pressures (?17% and ?25%, respectively; P < 0.001), sevoflurane minimum alveolar concentrations (?40% and ?44.5%, respectively; P < 0.001) and serum cortisol levels (?27% and ?34.6%, respectively; P < 0.001) and higher sedation scores for the first 15 min after extubation and greater uterine tone (P < 0.002). Apgar scores, NACS and acid–base status were similar in the four groups.ConclusionPreoperative administration of dexmedetomidine 0.4 and 0.6 μg/kg/h is effective in attenuating the maternal haemodynamic and hormonal responses to caesarean delivery under sevoflurane anaesthesia without adverse neonatal effects.