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H A Adams

Publications and source records attributed to H A Adams.

At least 91 records · Page 5Linked to original sources
PubMed1991

[The endocrine stress reaction in anesthesia and surgery--origin and significance].

Stress can be defined as a "reaction by living beings to any relevant impairment". The effect of anaesthesia on endocrine function is closely related to the actual stress concept based on the works by Cannon and Selye. Cannon described the role of catecholamines in stress and characterised the fight-flight reaction. Selye emphasised the role of the adrenocortical reaction defining the "general adaptation syndrome", which evolves in three stages ("alarm reaction", "stage of resistance", "stage of exhaustion"). Later, Henry postulated the dual stress concept. The sympathetic-adrenomedullary system is activated during the fight-flight reaction, thus representing an active role of the organism. The pituitary-adrenocortical system is activated during loss of control, submission and depression, especially in a social context. Main valid parameters of this endocrine stress response are adrenaline, noradrenaline, ADH, ACTH and cortisol. In the perioperative period, both pathways are "stressed". The most important factors are patient, operation, and anaesthesia. Anaesthesia can influence the stress response by afferent blockade (local anaesthesia), central modulation (general anaesthesia) or peripheral interactions with the endocrine system (etomidate). Up to now, a total peripheral blockade of the nociceptive system is impossible, due to surgical technique (destruction of nerve fibres) and release of mediator substances. With regard to reduction of endocrine stress response, inhalation anaesthesia with volatile anaesthetics and nitrous oxide may be less effective than neuroleptic, spinal or epidural anaesthesia. Immediately after extubation, rapid increases of endocrine parameters are observed. In addition to central modulation of pain and stress, both halothane and enflurane inhibit catecholamine release from the adrenal medulla. Neuroleptic anaesthesia and total intravenous anaesthesia are very potent and sufficient to control the increases in endocrine parameters even during major surgery, due to their central effects. Spinal and epidural anaesthesia alone as well as in combination with general anaesthesia can reduce the endocrine stress response more than necessary. This is due to the sympathetic blockade, combined with an afferent blockade of central cord fibers which modulate the pituitary-adrenocortical system. Only few data are available concerning the stress response during infiltration anaesthesia or nerve block, but additional sedation seems to be beneficial. Peripheral interactions with the endocrine system like blockade of the adrenal cortex by etomidate is dangerous and has caused a high mortality in intensive-care patients if the substance was admitted for a longer period. Assessment of endocrine stress response in anaesthesia and surgery is controversial.(ABSTRACT TRUNCATED AT 400 WORDS)

Anesthesia↗
PubMed1991

[Absorption of adrenaline after local administration to the eye].

Twenty patients undergoing surgery for correction of strabismus under general anesthesia were randomly selected to receive conjunctival application of 100 microliters (20 micrograms) adrenaline in both eyes or in neither (controls). A further 20 patients undergoing cataract surgery with local anesthesia were randomly selected to receive 1 ml adrenaline 1:10 000 (100 micrograms) or 1 ml balanced salt solution (controls) in the anterior chamber. Adrenaline in plasma was measured in six time points within 15 min (correction of strabismus) or at seven within 30 min (cataract surgery). Plasma levels of adrenaline, mean arterial pressure, and heart rate were comparable in treatment groups and controls. No severe arrhythmias were observed. Neither conjunctival application of 20 micrograms adrenaline or instillation of 100 micrograms adrenaline into the anterior chamber increases adrenaline levels in plasma, and there is no reason to suspect cardiovascular interactions.

Adolescent↗
PubMed1991

[The stress reaction in the recovery phase from halothane and isoflurane anesthesia].

This study was undertaken to investigate the influences of halothane and isoflurane as well as different extubation techniques on the endocrine stress response during recovery from general anesthesia. Forty patients scheduled for herniorrhaphy and cholecystectomy were randomly allocated to 4 groups: 20 received halothane and 20 received isoflurane anesthesia. Within the halothane and isoflurane groups, 10 patients each were extubated during anesthesia (1/2 MAC) and a further 10 had awake extubation. Premedication, induction of anesthesia, and intraoperative anesthetic management were standardized in all groups. Plasma levels of endocrine stress parameters as well as mean arterial pressure (MAP), heart rate (HR), and arterial oxygen saturation (SaO2) were measured at nine time points up to 60 min after extubation. Biometric data and duration of operation and anesthesia were comparable in all groups. In the recovery period, epinephrine levels were higher in the isoflurane groups than in the halothane groups (P = 0.02). With respect to time course, earlier and more marked increases of epinephrine, norepinephrine, and antidiuretic hormone (ADH) levels were observed in the isoflurane groups compared to the halothane groups (P less than 0.01), representing the more rapid elimination of isoflurane. The sympathoadrenergic stress response was more pronounced in patients with extubation during anesthesia than in those with awake extubation: epinephrine levels were slightly higher and group levels of norepinephrine were significantly increased (P = 0.02). No influence of the extubation techniques was observed on ADH, ACTH, and cortisol levels or on MAP, HR, or SaO2. In summary, extubation during anesthesia did not reduce the endocrine stress response. It is concluded that awake extubation should be preferred unless the operation or the patient's condition requires extubation during anesthesia.

Adult↗
PubMed1991

[The use of ketamine and midazolam for analgesia and sedation in ventilated patients subject to obligatory treatment with catecholamines].

This study was undertaken to compare two regimens for analgesic sedation in intensive care patients with exogenous catecholamine therapy, giving special regard to catecholamine demand and hemodynamic parameters. A total of 20 ventilated patients in a surgical intensive care unit were investigated in a prospectively randomized design. Exogenous catecholamine therapy with epinephrine and/or norepinephrine was started at systolic pressure (SAP) less than 85 mmHg or mean arterial pressure (MAP) less than 65 mmHg to maintain cardiovascular function. For analgesic sedation, patients received bolus injections of about 0.2 mg/h fentanyl and 2.5 mg/h midazolam (fentanyl group, n = 10) or an infusion of about 50 mg/h ketamine and 2.5 mg/h midazolam by syringe pump (ketamine group, n = 10). Before the investigation, all patients received fentanyl and midazolam. The study period was 48 h. During the course of the study, mean catecholamine dosage increased significantly in the fentanyl group from 12.1 to 16.3 micrograms/min (+33%, P = 0.003). In the ketamine group, mean catecholamine dosage decreased from 43.9 to 38 micrograms/min (-13%, P = 0.19). No significant differences in group levels or time course were observed with regard to MAP, heart rate, cardiac index, pulmonary capillary wedge pressure, and shunt volume. Levels of pulmonary artery pressure (PAP) were comparable in both groups (ketamine group 29 mmHg, fentanyl group 26 mmHg). In time course, PAP increased by about 5 mmHg in the ketamine group but not in the fentanyl group (P = 0.009). The average central venous pressure (CVP) was 12 mmHg in both groups. At the end of the investigation, CVP decreased in the fentanyl group and increased in the ketamine group (P = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Comparative effects of enoximone and theophylline on plasma catecholamines and haemodynamics in cardiosurgical patients.

The release of endogenous catecholamines in aorto-coronary bypass graft patients receiving either 0.5 mg/kg enoximone (n = 10), 4.0 mg/kg theophylline (n = 10) or saline solution (control, n = 10) has been studied, as well as certain haemodynamic parameters. Adrenaline (A) and noradrenaline (NA) concentrations were not significantly changed by the administration of enoximone. Theophylline caused a small increase in NA (+40% in the 1st min) and a marked increase in A (approximately +7000% in the 1st min), which still remained elevated at the end of the investigation period (+220% in the 30th min). The major haemodynamic effects of enoximone were a significant increase in cardiac index (CI; +35%) and a decrease in pulmonary capillary wedge pressure (PCWP; -27%), pulmonary artery pressure (PAP; -21%), RVEDV and RVESV, while the heart rate (HR) remained almost unchanged. The dominant haemodynamic effects of theophylline were an increase in HR (+26%; arrhythmia in 3 patients), PAP (+22%), and RVEDV (+19%), while RVESV (+26%), MAP (-16%), CI (-14%), and RVEF (-15%) fell significantly. It is concluded that the haemodynamic actions of enoximone are not mediated by catecholamine release, whereas the adverse cardiovascular effects of theophylline might partly be explained by the significant increase in plasma adrenaline.

Cardiac Catheterization↗
PubMed1990

Effects of nitrous oxide on endocrine stress response and haemodynamic parameters during coronary artery surgery.

To compare simultaneously the influence of nitrous oxide on haemodynamic parameters and on surgical stress response, 20 patients scheduled for coronary artery bypass graft were investigated during standardized modified neurolept anaesthesia. Before onset of cardiopulmonary bypass, one group received nitrous oxide and oxygen (2:1), whereas in the other group air with oxygen (F10(2) 0.33) was used. Increases in adrenaline, noradrenaline, ADH, and cortisol were slightly less and mean arterial pressure and cardiac output reached markedly lower levels in the nitrous oxide group. When nitrous oxide is not acceptable for a cardiac surgery patient during modified neurolept anaesthesia due to haemodynamic side effects enhancing intravenous application of anaesthetics to compensate the analgetic properties of the substance should be considered.

Adrenocorticotropic Hormone↗
PubMed1990

[Plasma level of lidocaine and adrenaline in local anesthesia with addition of colloid in eye surgery].

This study was undertaken to investigate the plasma levels of lidocaine and adrenaline after local anaesthesia for ophthalmic surgery and the influence of addition of hydroxyethyl starch (HES) on the resorption of the local anaesthetic solution. Prior to cataract surgery, two groups (each consisting of 10 patients) received a retrobulbar block (5 ml) and a facial nerve block (5 ml; O'Brien technique) with lidocaine 2% and adrenaline 1:80000, with or without addition of 10% HES 200/0.5 (relation 1:1) in equal volumes and concentrations. The plasma levels of lidocaine and adrenaline were measured by high-pressure liquid chromatography. In both groups, the individual peak concentrations of lidocaine (8.62 micrograms/ml) and adrenaline (7.514 pg/ml) reached the toxic range. There was no evidence of intravascular injection, and no severe cardiovascular reactions were observed. In 9 patients, resorption was slow and led to low peak concentrations. A rapid resorption with high peak concentrations was found in 11 patients. Peak levels of lidocaine were reached after 15 min and those of adrenaline after 3-5 min. Plasma levels of lidocaine and adrenaline were not significantly influenced by the addition of HES, although the highest peak concentrations were found in the group without the addition of HES.

Aged↗
PubMed1990

[Sympatho-adrenergic reactions during drug-induced hypotension. A comparative study on probands].

This study was undertaken to compare the influence of different regimens for induced hypotension down to Power a limit of 80 mmHg (systolic) on sympatho-adrenergic responses in 10 volunteers. Volunteers were investigated in five batteries of tests using glyceryl trinitrate (10 micrograms/kg BW/min), sodium nitroprusside (10 micrograms/kg BW/min maximal dosage), nifedipine (0.35 micrograms/kg BW/min) and urapidil (bolus injections of 25, 25 and 50 mg, followed by an infusion of 180 ml/h) and placebo. Catecholamines in plasma were detected by HPLC/ECD within a period of 1 h of hypotension and 1 h of recovery at 11 measuring points. Using sodium nitroprusside and glyceryl trinitrate, a significant hypotension was achieved. Urapidil was less potent. No hypotension was observed during or after treatment with nifedipine. Heart rate increased during treatment with sodium nitroprusside and glyceryl trinitrate. Sodium nitroprusside, glyceryl trinitrate and urapidil caused significant rises in noradrenaline levels. With nifedipine, noradrenaline increased within the normal range. Adrenaline left the normal range only during urapidil treatment. MAP, HR, and levels of noradrenaline and adrenaline returned to the initial values 5 min after discontinuation of the sodium nitroprusside infusion. After treatment with glyceryl trinitrate and urapidil, MAP was still low even 60 min after discontinuation of treatment. Urapidil caused marked increases in noradrenaline and adrenaline, which persisted even into the recovery phase. With regard to clinical management and sympatho-adrenergic responses, sodium nitroprusside is the most useful of these compounds for the reduction of hypotension. Having similar potency and active metabolites, glyceryl trinitrate has a longer duration of action.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[Endocrine reactions during acute normovolemic hemodilution].

To investigate the influence of acute normovolemic hemodilution (ANH) on endocrine parameters in orthopedic surgery patients, 20 patients scheduled for total prosthetic replacement of the hip under epidural anesthesia with bupivacaine 0.5% were randomly allocated to the following groups: ANH group, (about 7.5 ml/kg body weight within 30 min) during substitution with 6% HES 200/0.5; Control group (without hemodilution). During a period before the onset of anesthesia and on the 1st day after the operation, MAP, HR, plasma concentrations of adrenaline and noradrenaline (by HPLC/ECD), and of ADH, ACTH and cortisol (by RIA) were determined at 8 points, as were glucose, lactate and free glycerol. Biometric data were comparable between the groups. MAP was significantly higher in the ANH group, and the intraoperative decrease was less pronounced. Adrenaline, ACTH, and cortisol revealed no specific influence of ANH and remained within the normal range in both groups. Noradrenaline was above the normal range in both groups and increased slightly (about 20%) during ANH. ADH was significantly higher in the control group. No specific influence of ANH was found with respect to glucose, lactate and free glycerol. In conclusion, ANH had no negative effects on the endocrine stress response during orthopedic surgery under epidural anesthesia. Sympatho-adrenergic reactions were only moderate and tolerable, even for patients with compensated cardiovascular disorders. Slight increases in endocrine parameters in the perioperative period documented adequate stress protection with epidural anesthesia.

Adrenocorticotropic Hormone↗
PubMed1990

[Postoperative course and endocrine stress reaction of geriatric patients with para-articular hip fractures. Prospective randomized study comparing spinal anesthesia and halothane intubation narcosis].

During a period of one year, all patients above the age of 60 with surgical repair of fractured neck of femur were investigated in a prospectively randomized design. A follow-up study included a total number of 56 patients, 32 were allocated to halothane anaesthesia with intubation, 24 received spinal anaesthesia. In addition, 15 patients of the halothane group and 17 patients with spinal anaesthesia were investigated with regard to endocrine stress response. Total mortality was 12.5%, and different anaesthetic management had no influence on the postoperative course. During the operation, adrenaline and ADH increased in both groups. This increase was attenuated by spinal anaesthesia. Noradrenaline was markedly increased even before the operation, and concentrations increased in the halothane group in the course of the operation. There was a linear correlation to time between accident and the beginning of the operation. With regard to endocrine parameters, prompt surgical treatment is beneficial.

Adrenocorticotropic Hormone↗
PubMed1990

[20 years of ketamine--a backward look].

Twenty years ago, ketamine was introduced into clinical use in Germany. Since this time, advantages and disadvantages of "dissociative anesthesia" with ketamine have been reported in many studies. Improvements were seen in stabilization of blood pressure during induction of shock patients, induction of patients with asthma, and preservation of spontaneous breathing as well as protective reflexes. On the other hand, psychomimetic reactions and an increase in cardiac oxygen consumption restricted the clinical use of ketamine. The incidence of these side effects was reduced when ketamine was combined with benzodiazepines. In the course of time ketamine was used in obstetrics, as an analgesic agent, in burn patients, and in emergency and disaster medicine. The influence of ketamine on intracranial pressure and the endocrine stress response was investigated as well. Unconventional aspects were reported by several authors concerning oral, intrathecal, epidural, nasal, and rectal administration and the use of ketamine for intravenous regional anesthesia, whereby the local anesthetic properties of ketamine became evident. In conclusion, intravenous and intramuscular "sympathomimetic anesthesia" with ketamine has found its place in anesthesiology. Insufficient hypnotic properties can be diminished by combination with benzodiazepines. The main indications for ketamine are anesthesia and analgesia in emergency and disaster medicine. In clinical use, the substance is of benefit in the induction of anesthesia for cesarean section, in shock situations, for asthma patients, and for short operations and painful diagnostic procedures. Intramuscular administration is preferred in uncooperative patients and children. In intensive care medicine, ketamine is of special interest in patients with hypotensive circulatory dysregulation and in ventilator treatment of asthma patients.

Anesthesiology↗
PubMed1990

[Epidural conduction anesthesia versus general anesthesia. A critical evaluation of outcome studies using as examples cesarean section and patients with hip fractures].

In the field of anaesthesiology, outcome studies are undertaken to investigate the influence of different anaesthetic techniques on the intra- and postoperative course of patients in special clinical situations. The design of these studies should follow high methodological standards. In the past, most studies were undertaken in patients during Caesarean section and in the treatment of hip fractures in the elderly. Up to now, results do not clearly indicate the use of certain techniques in concrete clinical situations. Decisions must be made in accordance with clinical aspects, individual experience and in cooperation with the patient and the surgeon.

Adult↗
PubMed1990

[The significance of the sampling site in the determination of plasma levels of local anesthetics using 0.75% bupivacaine as an example].

Knowledge of the actual concentrations of local anesthetic administered by various techniques is essential requisite when undesirable side effects and possible toxicity of a substance are to be evaluated. Therefore, numerous studies of plasma concentrations have been presented, which were carried out with the additional purpose of analyzing the kinetics of different local anesthetics with respect to limiting-value concentrations in the organism. Despite a sufficient degree of precision in the analysis of amide local anesthetics, it is uncertain whether the results of the different studies are comparable, because blood samples have been taken variously from peripheral veins, central veins or arteries. In the present study changes in bupivacaine concentrations were monitored by means of a standardized method consisting in simultaneous sampling of blood in peripheral veins, central veins and arteries. METHODS. Each of 12 patients undergoing orthopedic hip surgery received average 17 ml bupivacaine (0.75%) via peridural lumbar catheter. After the administration of bupivacaine, blood samples were taken simultaneously from peripheral veins, central veins and arteries at 1, 3, 5, 10, 15, 30, 45, 60, and 90 min after injection. Placement of an arterial cannula and central venous catheter was indicated in all patients (hip-joint revision arthroplasty). Quantitative analysis of bupivacaine concentration was carried out by means of high-pressure liquid chromatography (HPLC). All patients had given their informed consent. RESULTS. All patients showed a rapid increase in bupivacaine concentration in the central venous blood within the first few minutes after administration, the maximum being reached between 3 and 10 min after. A similar course was observed with arterial plasma concentrations; absolute values, however, were an average of 10-20% lower at 15 min following administration. Bupivacaine concentrations in peripheral veins rose more slowly and reached a maximum between 15 and 30 min. At 30 min after peridural application the concentration curves in blood from all three sites were similar. DISCUSSION. In earlier studies the influence of the site of blood sampling has often been underestimated. According to our results, central venous and arterial plasma concentrations correspond closely at all times following peridural application. The observed uniform differences in concentrations at the various sites of sampling can be explained by the fact that pulmonary uptake of local anesthetics causes the lower arterial levels. Especially in the early phase of resorption after administration of local anesthetics, the concentration in peripheral blood does not seem to be representative, because an equilibrium is not established between arterial and central venous blood until 30 min after administration at the earliest. In our opinion the peripheral venous concentrations are unreliable, particularly in the early phases, for the evaluation of unwanted effects or toxicity of local anesthetics, because the initial low values and the delayed increase in these could lead to a false sense of security.

Aged↗
PubMed1989

[The sympatho-adrenergic stress reaction in ear surgery using various anesthesia technics].

The aim of the present study was to investigate the effects of various anaesthetic procedures on the endocrine stress responses during ear microsurgical operations. Simple mastoidectomies, radical mastoidectomies and tympano plastics were carried out in 49 patients under the following randomised anaesthetic procedures: Group 1 halothane anaesthesia and retroauricular infiltration anaesthesia with lidocaine and ornipressin (n = 14), Group 2 fentanyl anaesthesia and retroauricular anaesthesia with lidocaine and ornipressin (n = 10), Group 3 fentanyl anaesthesia and retroauricular infiltration anaesthesia with lidocaine and epinephrine (n = 14), and Group 4 retroauricular infiltration anaesthesia with prilocaine and epinephrine (n = 14). The plasma levels of epinephrine, norepinephrine, glucose, lactate and free glycerol were measured in addition to mean arterial pressure (MAP) and heart rate (HR) immediately before anaesthesia, 10 minutes after skin incision, 10 minutes after having started bone drilling, at the end of the operation and 3 hours after operation. All data were subjected to covariance analysis including the age factor. Plasma catecholamine concentrations remained within the normal range during the investigation in patients subjected to general anaesthesia (Groups 1-3). Plasma catecholamines (epinephrine and norepinephrine) increased significantly in Group 4 (retroauricular infiltration anaesthesia). There were no group variabilities with regard to MAP and HR. The plasma levels of epinephrine and norepinephrine demonstrate a direct response to stress followed by a secondary change in glucose, lactate and free glycerol. The beneficial effect of general anaesthesia is documented by normal plasma levels of epinephrine and norepinephrine throughout the operation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[Mother and child stress parameters during cesarean section with general and peridural anesthesia].

This study compared maternal and fetal stress responses during cesarean section in either general anesthesia (GA) or epidural anesthesia (EA). Ten patients received GA with thiopental induction, intubation, and controlled ventilation with nitrous oxide and oxygen. After delivery, anesthesia was supplemented with fentanyl 0.2-0.3 mg. Ten patients received EA via catheter, using bupivacaine 0.5%, and prilocaine or lidocaine 1%. Maternal mean arterial pressure (MAP), HR, and plasma concentrations of epinephrine and norepinephrine (by HPLC/ECD), ADH, ACTH and cortisol (by RIA) were determined before and after induction, after delivery, at the end of the operation and 30 minutes postoperatively. Fetal catecholamine levels in umbilical artery blood were measured immediately after delivery. In addition, fetal blood gas analyses and Apgar scores were compared. Fetal epinephrine was slightly increased in the EA group (EA 132 pg/ml, GA 52 pg/ml). Norepinephrine was similar in both groups (EA 1.218 pg/ml, GA 1.124 pg/ml). Blood gas analyses and Apgar scores were also comparable. A negative correlation was found between norepinephrine and pH values in fetal umbilical artery blood (P = 0.01). Maternal epinephrine levels were lower under EA and below the normal range (EA 23 pg/ml, GA 77 pg/ml, P = 0.002); levels increased during GA and decreased during EA (P = 0.01). No statistical differences were seen in maternal norepinephrine (EA 206 pg/ml, GA 354 pg/ml). MAP was lower during EA (group levels EA 81 mmHg, GA 95 mmHg, P = 0.0002) and HR was higher during GA (group levels EA 89/min, GA 104/min, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗
PubMed1989

[Sympatho-adrenergic reactions following theophylline administration with the use of various anesthesia technics].

The mechanism of action of theophylline is still the subject of controversy. Possible mechanisms that have been suggested are inhibition of phosphodiesterase, release of catecholamines, effects on intracellular calcium, and adenosine antagonism. With regard to these aspects, it was the aim of this study to compare sympatho-adrenal responses after theophylline application during different anesthetic techniques. A total of 60 patients scheduled for orthopedic surgery were investigated: they were divided into three groups of 20 patients who received either halothane anesthesia with thiopentone induction, modified neurolept anesthesia with fentanyl and midazolam, or spinal anesthesia with bupivacaine and mepivacaine. Within these three groups, the patients were randomly allocated to a theophylline collective receiving an injection of theophylline, 4 mg/kg body weight and to the control group. Plasma levels of epinephrine and norepinephrine (by HPLC/ECD), glucose, lactate and free glycerol and MAP and HR were determined over a period of 120 min. In all groups, epinephrine levels increased immediately after injection of theophylline; group levels of epinephrine were higher in the theophylline-groups than in controls (P less than 0.0001). A remarkable increase was observed within 60 min. Peak epinephrine concentrations were comparable after single injections of 100 micrograms or infusions of 5 micrograms/min. The norepinephrine increase after theophylline injection was brief and less pronounced. MAP, HR, glucose, lactate and free glycerol were not influenced by theophylline. A comparison of the theophylline patients showed no statistical differences attributable to the different anesthetic techniques.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[The quantitative analysis of amide local anesthetics using high pressure liquid chromatography and ultraviolet detection (HPLC/UV)].

This study was undertaken to develop a time- and cost-effective method for the detection of lidocaine, mepivacaine, prilocaine, bupivacaine, and etidocaine by HPLC/UV. The chromatographic system consisted of a C18-column (300 x 3.9 mm) for reversed-phase chromatography and a mobile phase of 30% acetonitrile and 70% 0.05 M sodium phosphate buffer. For the analysis of lidocaine, mepivacaine, and prilocaine, the buffer was adjusted to pH 5.8. The buffer for the analysis of bupivacaine and etidocaine was adjusted to pH 3.5. The flow rate was 1 ml/min. UV detection took place at a wavelength of 210 nm. All blood samples were taken from a central venous line. After plasma separation, 1 microgram (100 microliters) of internal standard was added to 1 ml plasma. The samples were alkalized and extracted with ether, followed by the extraction of the organic phase in 250 microliters 0.05 N sulphuric acid; 50 microliters of this solution was injected into the system. The chromatographic system allowed the separation of bupivacaine and etidocaine (pH 3.5) as well as lidocaine and mepivacaine or prilocaine (pH 5.8). Separation of prilocaine and mepivacaine in one run was not satisfactory. Recovery rates for all local anesthetic substances were about 90%, standard variations below 3%, and coefficients of variation below 2%. The detection limit was about 30 ng/ml. The method is suitable for clinical practice. Only minor methodological modifications are necessary for the detection of the amide local anesthetics in current clinical use.

Anesthetics, Local↗