The haemodynamic effects of rocuronium and vecuronium are different under balanced anaesthesia

BACKGROUND: Rocuronium has been reported to have minimal haemodynamic effects. However, this conclusion has been drawn primarily from investigations conducted under narcotic-based anaesthesia. This study was designed to evaluate the cardiovascular effects of rocuronium under isoflurane/N2O/fentanyl anaesthesia and to compare rocuronium's haemodynamic effects to those of vecuronium and pancuronium. METHODS: Anaesthesia was induced with fentanyl 2 micrograms/kg, thiopentone 4 mg/kg, and suxamethonium 0.5 mg/kg in 75 ASA I or II patients. After tracheal intubation, anaesthesia was maintained with isoflurane 0.5% and N2O 50% in oxygen. Five min after intubation (baseline), patients randomly received either vecuronium 100 micrograms/kg, rocuronium 600 micrograms/kg, rocuronium 900 micrograms/kg, rocuronium 1200 micrograms/kg, or pancuronium 140 micrograms/kg. One min after administration of muscle relaxant, mean arterial pressure (MAP) and heart rate (HR) were recorded and were subsequently measured at 1-min intervals for the next 4 min. RESULTS: HR decreased significantly (P < 0.05) at all times compared to baseline in patients receiving vecuronium. HR significantly (P < 0.05) increased in those receiving rocuronium 1200 micrograms/kg or pancuronium. Patients who received vecuronium had a significant (P < 0.05) decrease in MAP at all times compared to baseline. Comparing results between groups, patients who received rocuronium or pancuronium had significantly (P < 0.05) higher MAP compared to those administered vecuronium. CONCLUSION: The haemodynamic effects of rocuronium and vecuronium are different under balanced anaesthesia. Rocuronium may attenuate the fall in MAP that often occurs under balanced anaesthesia without surgical stimulation.     

The use of nefopam in the prophylaxis and treatment of postoperative shivering]

Chlorhydrate nefopam was used in the prophylaxis and treatment of postoperative shivering in 54 patients undergoing general anesthesia for radical cystectomy with trans-intestinal anastomosis. Postoperative shivering was not observed in any of the patients treated with nefopam before coming round, whereas it occurred in 55% of patients treated with placebo. Chlorhydrate nefopam subsequently stopped shivering in all these patients. The main side effects observed took the form of delayed awakening in 11% of patients receiving prophylactic treatment and somnolence lasting 5-10 minutes in all other patients.     

Endocrine stress reaction, hemodynamics and recovery in total intravenous and inhalation anesthesia. Propofol versus isoflurane

This prospective, randomised study compared total intravenous anaesthesia (TIVA) and inhalation anaesthesia with respect to endocrine stress response, haemodynamic reactions, and recovery. METHODS. The investigation included two groups of 20 ASA I-II patients 18-60 years of age scheduled for orthopaedic surgery. For premedication of both groups, 0.1 mg/kg midazolam was injected IM. Patients in the propofol group received TIVA (CPPV, PEEP 5 mbar, air with oxygen FiO2 33%) with propofol (2 mg/kg for induction followed by an infusion of 12-6 mg/kg.h) and fentanyl (0.1 mg before intubation, total dose 0.005 mg/kg before surgery, repetition doses 0.1 mg). For induction of patients in the isoflurane-group, 5 mg/kg thiopentone and 0.1 mg fentanyl was administered. Inhalation anaesthesia was maintained with 1.2-2.4 vol.% isoflurane in nitrous oxide and oxygen at a ratio of 2:1 (CPPV, PEEP 5 mbar). For intubation of both groups, 2 mg vecuronium and 1.5 mg/kg suxamethonium were injected, followed by a total dose of 0.1 mg/kg vecuronium. Blood samples were taken through a central venous line at eight time points from before induction until 60 min after extubation for analysis of adrenaline, noradrenaline (by HPLC/ECD), antidiuretic hormone (ADH), adrenocorticotropic hormone (ACTH), and cortisol (by RIA). In addition, systolic arterial pressure (SAP) heart rate (HR), arterial oxygen saturation (SpO2), and recovery from anaesthesia were observed. RESULTS. Group mean values are reported; biometric data from both collectives were comparable (Table 1). Plasma levels of adrenaline (52 vs. 79 pg/ml), noradrenaline 146 vs. 217 pg/ml), and cortisol (82 vs. 165 ng/ml) were significantly lower in the propofol group (Table 2, Figs. 1 and 3). Plasma levels of ADH (4.8 vs. 6.1 pg/ml) and ACTH (20 vs. 28 pg/ml) did not differ between the groups (Table 2, Figs 2 and 3). SAP (128 vs. 131 mmHg) was comparable in both groups, HR (68/min vs. 83/min) was significantly lower in the propofol group, and SpO2 (97.1 vs 97.4%) showed no significant difference (Table 3). Recovery from anaesthesia was slightly faster in the propofol group (following of simple orders 1.9 vs. 2.4 min, orientation with respect to person 2.4 vs. 3.4 min, orientation with respect to time and space 2.8 vs. 3.7 min), but differences failed to reach statistical significance. CONCLUSIONS. When compared with isoflurane inhalation anaesthesia, moderation of the endocrine stress response was significantly improved during and after TIVA with propofol and fentanyl. Slightly shorter recovery times did not lead to an increased stress response. With respect to intra- and postoperative stress reduction, significant attenuation of sympatho-adrenergic reaction comparable SAP and reduced HR, sympatholytic and hypodynamic anaesthesia with propofol and fentanyl seems to be advantageous for patients with cardiovascular and metabolic disorders. For this aim, careful induction and application of individual doses is essential.     

Prolonged disease-free survival by maintenance chemotherapy among patients with recurrent platinum-sensitive ovarian cancer

The aim of this prospective, randomized and double-blind study was to assess the effects of a high dose of the analgesic tramadol administered at the conclusion of surgery on extubation time, sedation, and post-anaesthetic shivering. Forty adult patients, ASA physical status I or II, underwent laparoscopic surgery of about 1 h duration and received a standardized anaesthesia that was maintained with isoflurane in O2/N2O. Tramadol 3 mg kg-1 (n = 20) was administered intravenously at the beginning of wound closure, and was compared with saline (n = 20). Post-anaesthetic shivering did not occur in any patient who received tramadol, whereas it occurred in 60% of the control group (P < 0.001). There were no adverse effects on time to extubation and sedation, and discharge-ready time was shorter in the tramadol group (P < 0.05 compared with control). Pain scores in the post-anaesthesia care unit (PACU) were statistically not different between the two groups, but significantly more supplemental medication was administered in the control group to treat shivering and/or pain. In conclusion, administration of a high dose of tramadol at the end of surgery prevents post-anaesthetic shivering without prolongation of extubation time, and shortens the PACU/discharge-ready time.     

Postanaesthetic shivering--a comparison of thiopentone and propofol

One hundred and sixty patients undergoing minor surgical procedures were randomly allocated to receive either thiopentone or propofol for induction of anaesthesia. All patients were assessed in the recovery period for the development of postanaesthetic shivering. Twenty patients (25%) in the thiopentone group and 8 patients (10%) in the propofol group developed postanaesthetic shivering (p < 0.05). There was no statistically significant difference in tympanic temperature between shivering and nonshivering patients. Propofol as an induction agent is associated with a lower incidence of postanaesthetic shivering as compared to thiopentone.     

Propofol or midazolam for sedation and early extubation following cardiac surgery

PURPOSE: The purpose of this randomized, double-blind study was to evaluate the efficacy of midazolam and propofol for postoperative sedation and early extubation following cardiac surgery. METHODS: ASA physical status II-III patients scheduled to undergo elective first-time cardiac surgery with an ejection fraction > 45% were eligible. All patients received a standardized sufentanil/isoflurane anaesthesia. During cardiopulmonary bypass 100 micrograms.kg-1.min-1 propofol was substituted for isoflurane. Upon arrival in the Intensive Care Unit (ICU), patients were randomized to either 10 micrograms.kg-1.min-1 propofol (n = 21) or 0.25 microgram.kg-1.min-1 midazolam (n = 20). Infusion rates were adjusted to maintain sedation within a predetermined range (Ramsay 2-4). The infusion was terminated after four hours. Patients were weaned from mechanical ventilation and their tracheas extubated when Haemodynamic stability, haemostasis, normothermia and mental orientation were confirmed. Haemodynamic measurements, arterial blood gas tensions and pulmonary function tests were recorded at specified times. RESULTS: There were no differences between the two groups for the time spent at each level of sedation, number of infusion rate adjustments, amount of analgesic and vasoactive drugs, times to awakening and extubation. The costs of propofol were higher than those of midazolam. There were no differences in haemodynamic values, arterial blood gas tensions and pulmonary function. CONCLUSION: We conclude that midazolam and propofol are safe and effective sedative agents permitting early extubation in this selected cardiac patient population but propofol costs were higher.     

A study of cumulative effects and recovery from anaesthesia with intermittent doses of althesin. A comparison with methohexitone

The cumulative effects and post-anaesthetic recovery of Althesin were studied by comparing the drug with methohexitone in a series of 60 patients undergoing surgery for varicose veins. Anaesthesia was maintained with each anaesthetic agent in 30 patients by administration of intermittent doses of the respective drugs in accordance with the surgical stimulus. When repeat doses were required at intervals of 2 to 5 minutes, the fall off in requirements was observed with both anaesthetics, more distinctly with Althesin than with methohexitone. No significant difference could be observed in the time required for immediate awakening after the two drugs. However, the majority of the patients anaesthetized with Althesin displayed a peculiar lack of mental clarity for a short period after recovering consciousness. The recovery from anaesthesia was studied by various tests and observations. Recovery after Althesin appeared to proceed slightly faster than after methohexitone. When Althesin was required in high total dosage (exceeding 150 mu1/kg), the immediate awakening was associated with emotional upset and confusion. Frequency of nausea and vomiting after anaesthesia was considerably higher in the Althesin group than in the methohexitone group. These symptoms might be toxic due to the excessive dosage given. Using the induction time as a basis for calculation of the potency ratio, Althesin and methohexiton were found to have the ratio of 1:33 (expressed in mu1/kg : mg/kg).     

Decrease in costs for management of lower airway disease in the pediatric intensive care unit

PURPOSE: Hypertensive patients exhibit exaggerated cardiovascular responses to tracheal extubation. This study was undertaken to examine the inhibitory effects of calcium channel blockers, nicardipine and diltiazem, on haemodynamic changes after tracheal extubation. METHODS: Sixty hypertensive patients (ASA physical status II) undergoing elective orthopaedic (upper and lower extremity) surgery received, in a randomized, double-blind manner, 30 micrograms.kg-1 nicardipine, 0.2 mg.kg-1 diltiazem or saline (as a control) (n = 20 of each) i.v. before tracheal extubation. Changes in heart rate (HR), mean arterial pressure (MAP) and rate-pressure product (RPP) were measured before and after tracheal extubation. RESULTS: The HR, MAP and RPP increased after tracheal extubation in the control group (P < 0.05). The increases in these haemodynamic variables were attenuated with nicardipine or diltiazem. The inhibitory effects of diltiazem on these cardiovascular responses to tracheal extubation were greater than those of nicardipine (HR; 86 +/- 7 vs 101 +/- 10, RPP; 11,437 +/- 1,575 vs 14,675 +/- 2,874, mean +/- SD, P < 0.05). CONCLUSION: Compared with nicardipine, administration of diltiazem produced greater attenuating the circulatory responses to tracheal extubation in hypertensive patients.     

Simple strategy for sequencing cDNA clones

This randomized, open-label study compared the investigational inhalational anesthetic sevoflurane with isoflurane in 47 healthy women undergoing elective ambulatory surgery. The women were randomized to receive either sevoflurane or isoflurane in 60% nitrous oxide-oxygen. Induction with thiopental 3-6 mg/kg was followed by vecuronium 0.1 mg/kg and fentanyl 0-200 micrograms. Duration of anesthesia, time to emergence, orientation, length of stay in the surgical unit, and hospital discharge were recorded. The emergence, length of stay, and discharge times after discontinuation of sevoflurane were 9.7 +/- 0.7, 120.6 +/- 8.0, and 244 +/- 15 minutes, respectively, and for isoflurane were 11.9 +/- 1.4, 106.8 +/- 7.1, and 282 +/- 24 minutes, respectively (NS). The isoflurane group had a higher frequency of postoperative cough. At the end of surgery, the sevoflurane group received a deeper level of anesthesia (minimum alveolar concentration 1.5 vs 1.3), however, these patients were oriented earlier (13.6 +/- 1.1 min vs 17.0 +/- 1.5 min isoflurane; p = 0.02) after discontinuation of anesthesia, although this difference is of little clinical significance.     

Phosphoryl transfer reaction regulated by amino acid side chains: a model for phosphoproteins

STUDY OBJECTIVE: To compare the safety and effectiveness of 0.25 mg divided doses of mivacurium chloride to succinylcholine for a 90-second tracheal intubation. DESIGN: Randomized, double-blind, multicenter study in two groups. SETTING: Operating rooms at four university medical centers. PATIENTS: 200 healthy ASA status I and II adult patients scheduled for elective surgery with general anesthesia and endotracheal intubation. INTERVENTIONS: Patients were premedicated with 1 to 2 mg midazolam and 2 micrograms/kg fentanyl. Anesthesia was induced with 2 mg/kg propofol. Group A received 0.25 mg/kg mivacurium given as a divided dose (0.15 mg/kg followed in 30 seconds with 0.1 mg/kg). Group B (control) received 1.5 mg/kg succinylcholine (SCh) preceded two minutes earlier by 50 micrograms/kg d-tubocurarine (dtc). MEASUREMENTS AND MAIN RESULTS: Tracheal intubation grading, train-of-four response of the adductor pollicis, heart rate (HR), and mean arterial blood pressure (MAP) were measured and evaluated. Chi-square analysis was performed for comparison between Group A and Group B with respect to the frequency distribution of intubation using the scores excellent, good, and poor and not possible (combined). Group B had a significantly higher excellent score of intubation than Group A, 84% versus 56% (p < 0.0001). No significant difference was found between the two groups when the scores excellent and good were combined (Fisher's Exact test, p = 0.28). The changes in MAP and HR were similar for the two groups. CONCLUSIONS: When Sch is not desirable, mivacurium 0.25 mg/kg given as a divided dose provides good to excellent intubation conditions 90 seconds after the initial dose without significant changes in MAP or HR. It can be an appropriate alternative for short surgical procedures. It must be emphasized that this conclusion does not apply to rapid-sequence induction-intubation.     

Is there reliable experimental evidence for a chromosomal "fingerprint" of exposure to densely ionizing radiation?

BACKGROUND: As an inhibitor of the reuptake of serotonin and norepinephrine in the spinal cord, the mechanism of action of tramadol resembles that of nefopam, which has been used in the treatment of postanesthetic shivering. METHODS: In a randomized, placebo-controlled, double-blind study, we assessed the effects of tramadol (0.5 mg.kg-1, 1 mg.kg-1 and 2 mg.kg-1 i.v.) or normal saline on shivering after a standardized general anesthesia in 40 adult patients, ASA physical status I or II (group 1), and in 64 adult patients regardless of the foregoing general anesthesia and ASA physical status (group 2). RESULTS: Tramadol 1 mg.kg-1 or more abolished shivering completely 5 min after treatment in all patients of groups 1 and 2. In group 1, the three dosages of tramadol were not statistically different in lowering the severity and prevalence of postanesthetic shivering. Tramadol 0.5 mg.kg-1 was significantly slower than tramadol 1 or 2 mg.kg-1 in tempering the severity as well as lowering the prevalence of postanesthetic shivering in group 2. CONCLUSION: Tramadol's distinct features in the treatment of shivering reside in its high safety profile and weak sedative properties, particularly in patients with poor cardiorespiratory reserve, in outpatients and on recurrence of shivering.     

Effect of remifentanil on clinical and electroencephalographic parameters of depth of anesthesia in balanced anesthesia with propofol, enflurane or isoflurane

Electrophysiological parameters are well-suited to detect changes in cerebral function. The present study investigates whether balanced anaesthesia with remifentanil during nociceptive stimulation is associated with changes in clinical and electrophysiological parameters indicating inadequate depth of anaesthesia. Following IRB approval and written informed consent, 23 patients (ASA: I; age: 36 +/- 11) scheduled for elective gynaecological laparoscopy were included in the study. Without any premedication, anaesthesia was induced with remifentanil (1.0 microgram/kg bolus injection), propofol (0.5 mg/kg added by repetitive (10 mg) bolus injections every 10 s until unconciousness) and vecuronium (0.1 mg/kg). Following endotracheal intubation (normoventilation: PetCO2: 36 bis 38 mmHg), remifentanil infusion was started with continuous doses of 0.5 microgram/kg/min over 5 minutes and maintained with 0.25 microgram/kg/min during surgery. Remifentanil was randomly combined with propofol (group 1: 100 micrograms/kg/min; n = 7), enflurane (group 2: 0.5 MAC; n = 8) or isoflurane (group 3: 0.5 MAC; n = 8). Monitoring included: heart rate (beats/min), mean arterial pressure (mmHg), oxygen saturation (%), endtidal CO2 (mmHg) and endtidal enflurane and isoflurane (%). EEG: 2-channel recordings of Fz versus mastoid and ECG (artefact control) during steady-state anaesthesia and surgery. Following fast-fourier-transformation (4 s; 256/s; 0.5 to 35.0 Hz), spectral power densities were calculated for the selected frequency bands. Auditory evoked potentials (AEP; middle latency) were registered simultaneously after binaural stimulation via head-phones click-stimulation (6 Hz; 75 dB above hearing threshold; 512 stimulations per average). Bandpass was 0.01 to 2.0 kHz. Analysis: Na, Pa, Nb (latencies; ms) and peak-to-peak amplitudes (NaPa, PaNb; microV). EEG and AEP recording technique [15]. The study protocol included baseline values from pre-intubation, pre-surgery, the respective post-stimulation values (1 min, 3 min, 5 min) and all data at five-minute intervals during surgery until emergence from anaesthesia. During steady-state study conditions with defined remifentanil applications, mean data indicate that in response to nociceptive stimuli no changes in clinical or electrophysiological parameters were observed. In contrast to other studies using different anaesthetic techniques, the present data from remifentanil indicate very stable haemodynamic and electrophysiological parameters (EEG, AEP) during noxious stimulations. Adjustable and with no plasma accumulation, remifentanil demonstrates potent antinociceptive effects resulting in signs of adequate anaesthesia.     

ST segment changes in the ECG. Anesthesia induction with propofol, etomidate or midazolam in patients with coronary heart disease

Induction of anaesthesia with propofol and fentanyl can lead to marked reductions in mean arterial pressure (MAP) and heart rate (HR). Thus, the application of propofol in patients with severely reduced coronary artery perfusion is controversial. METHODS. The study group consisted of 60 patients undergoing coronary artery bypass grafting (CABG). Anaesthesia was induced over 30 s with propofol (P 1.5 mg/kg), etomidate (E 0.3 mg/kg), or midazolam (M 0.15 mg/kg) following a bolus dose of fentanyl (5 micrograms/kg). Vecuronium was used as a muscle relaxant. During induction we continuously measured MAP and HR and recorded the occurrence of myocardial ischaemia using an automatic ST-segment analyser (Marquette 7010). ST-segment deviations of more than 1 mm in leads II and V5 were interpreted as significant signs of myocardial ischaemia. RESULTS. All groups showed reductions in MAP and HR on induction that were marked in the P group. Intubation caused elevation of MAP and HR to pre-induction levels (HR: all groups) or slightly above (MAP: E, M). Four patients in the P group and 3 in each other group showed significant ST-segment deviation prior to induction. In the P group these deviations disappeared in 2 patients after injection while they remained unchanged in the M group. In the E group injection had no effect on the ischaemic ECG changes but produced another case of significant ST-segment deviation. Laryngoscopy and intubation produced no further significant ST-segment deviation in either group. DISCUSSION. Induction is a critical phase of anaesthesia, especially in patients with limited coronary reserve. Induction agents should alleviate the stress response while causing minimal haemodynamic changes. Despite marked reductions in MAP in the P group, the number of patients with ischaemic ECG changes was cut by half. Their number was unchanged or even raised in the other groups. After application of P, with an alleged reduction of coronary perfusion, a compensational reduction in myocardial oxygen consumption may occur.     

Comparison between alfentanil, pethidine and placebo in the treatment of post-anaesthetic shivering

We have compared the effects of pethidine, alfentanil and placebo in the treatment of post-anaesthetic shivering. Ninety patients who shivered after routine surgery were allocated randomly to receive normal saline (n = 30), alfentanil 250 micrograms (n = 30) or pethidine 25 mg (n = 30). After 10 min, 26 patients had stopped shivering in the pethidine group which was significantly more than the incidence in the two other groups (placebo = 7; alfentanil = 12) (P < 0.0002). Alfentanil was not significantly different from normal saline in affecting shivering. We conclude that alfentanil 250 micrograms was not effective in the treatment of post-anaesthetic shivering.     

Shivering threshold during spinal anesthesia is reduced in elderly patients

BACKGROUND: Both accidental and perioperative hypothermia are common in the elderly. The elderly are at risk because their responses to hypothermia may be delayed or less efficient than in those of younger subjects. For example, the vasoconstriction threshold during isoflurane anesthesia is approximately 1 degree C less in elderly than younger patients. However, the extent to which other cold defenses are impaired in the elderly remains unclear, especially in those older than 80 yr. Operations suitable for spinal anesthesia provided an opportunity to quantify shivering thresholds in patients of varying ages. Accordingly, the hypothesis that the shivering threshold is reduced as a function of age during spinal anesthesia was tested. METHODS: Twenty-eight ASA Physical Status 1-3 patients undergoing lower extremity orthopedic procedures were studied. Spinal anesthesia was induced without preanesthetic medication, using bupivacaine sufficient to produce a dermatomal level near T9. Electrocardiogram signals were recorded at 10-min intervals. Subsequently, an observer masked to patient age and core temperature identified the onset of sustained electromyographic artifact consistent with shivering. The tympanic membrane temperature triggering shivering identified the threshold. RESULTS: Three patients did not shiver at minimum core temperatures exceeding 36.2 degrees C. Fifteen patients aged < 80 yr (58 +/- 10 yr) shivered at 36.1 +/- 0.6 degrees C; in contrast, ten patients aged > or = 80 yr (89 +/- 7 yr) shivered at a significantly lower mean temperature, 35.2 +/- 0.7 degrees C (P = 0.002). The shivering thresholds in seven of the ten patients older than 80 yr was less than 35.5 degrees C, whereas the threshold equaled or exceeded this value in all younger patients (P = 0.0002). CONCLUSIONS: Age-dependent inhibition of autonomic thermoregulatory control in the elderly might be expected to result in hypothermia. That it usually does not suggests that behavioral regulation (e.g., increasing ambient temperature, dressing warmly) compensates for impaired autonomic control. Elderly patients undergoing spinal anesthesia, however, may be especially at risk of hypothermia because low core temperatures may not trigger protective autonomic responses. Furthermore, hypothermia in the elderly given regional anesthesia may not be perceived by the patient (who typically feels less cold after induction of the block), or by the anesthesiologist (who does not observe shivering). Consequently, temperature monitoring and management usually is indicated in these patients.     

A case report of complete inversion of the bladder in an old woman

BACKGROUND: The inhaled anaesthetic desflurane is characterized by a rapid wash-in and wash-out and may be useful for short paediatric ENT procedures. Therefore, this study was designed to compare the effects of desflurane or isoflurane on intubating conditions and recovery characteristics in paediatric ENT patients. METHODS: In this prospective, randomised investigation, we studied 44 children scheduled for ENT surgery, aged 4-12 yr and classified ASA I-II. After thiopentone induction (5-8 mg/kg) the lungs were ventilated by face mask and the vaporizer was dialed to 1 MAC (age-adapted) of desflurane of isoflurane. A reduced dose of vecuronium (0.05 mg/kg) was administered, and intubating conditions were rated 3 min later. Following tracheal intubation, 50% nitrous oxide were added, and the concentration of desflurane or isoflurane was adjusted according to clinical needs. At the end of surgery all anaesthetics were discontinued simultaneously and recovery times were recorded. RESULTS: Intubating conditions were rated significantly better for desflurane (excellent or good 20 of 22) than for isoflurane (12 of 22). Recovery times were significantly shorter for desflurane than for isoflurane (mean +/- SE): spontaneous ventilation 4.0 +/- 0.5 min vs. 6.0 +/- 0.7 min, extubation 8.4 +/- 0.7 vs. 11.4 +/- 1.1 min and arrival at PACU 11.5 +/- 0.8 vs. 16.6 +/- 1.5 min. No airway complications (coughing, laryngospasm, or desaturation < 97%) were noted for either anaesthetic. CONCLUSIONS: Following an intravenous induction improved intubating conditions, shorter recovery times and the lack of airway complications make desflurane a suitable alternative to isoflurane for paediatric ENT anaesthesia.     

Circulatory changes during anesthetic induction: impact of d-tubocurarine pretreatment, thiamylal, succinylcholine, laryngoscopy, and tracheal lidocaine

Circulatory changes after IV d-tubocurarine (3 mg), thiamylal (4 mg/kg) plus succinylcholine (2 mg/kg) and followed by direct laryngoscopy with or without intratracheal lidocaine spray (2 mg/kg) just before endotracheal intubation (EI), were measured in 40 adult patients. Pretreatment with d-tubocurarine did not alter mean arterial pressure (MAP), heart rate (HR), or central venous pressure (CVP). One minute after thiamylal-succinylcholine and just before laryngoscopy, MAP was 15 torr less than the awake value (p less than 0.05) and HR was 13 beats/min greater than the awake value (p less than 0.05). Laryngoscopy and EI elevated MAP above awake levels and further increased HR in all patients. The magnitude of these responses immediately following EI was not altered by tracheal lidocaine. However, the pressor and HR changes following EI were more transient when tracheal lidocaine was used (20 patients) and these patients were more likely to tolerate the tracheal tube without immediate additional anesthesia. The incidence of ventricular dysrhythmias was not altered by tracheal lidocaine. Compared with awake values, the cardiac index did not change significantly following intubation but stroke volume was decreased (p less than 0.05), with or without tracheal lidocaine.     

Osmotic concentration of polypeptides from hemofiltrate of uremic patients

In order to clarify the interactions between various doses of thiopental and fentanyl in producing "balanced anaesthesia", their effects on consciousness, superficial nociception, and respiration and circulation were studied during N2O+O2 inhalation in connection with the induction of anaesthesia. Altogether 60 patients were studied; the drug combinations used were thiopental 5 mg/kg (TP5), thipental 3 mg/kg (TP3), thiopental 3 mg/kg and fentanyl 0.5 micrograms/kg (TP3F0.5), thiopental 2 mg/kg and fentanyl 1 micrograms/kg (TP2F1), thiopental 1 mg/kg and fentanyl 2 micrograms/kg (TP1F2), and fentanyl 3 micrograms/kg (F3). Five minutes after the i.v. supplementation of N2O+O2 anaesthesia, the depth of anaesthesia and analgesia (antinociception) were evaluated from the eyelid reflex and by pinching an inguinal skin fold. Cardiorespiratory parameters were measured during this study period at 1-min intervals. The balance between antinociception and anaesthesia was closest to optimum in groups TP2F1 and TP2F0.5. In pure thiopental groups, the analgesia was poor; only four patients did not respond to the nociceptive stimulus, whereas in group F3 anaesthesia (disappearance of the eyelid reflex) was obtained in only two patients. The respiratory depression was most pronounced in groups receiving 3, 2 and 1 micrograms/kg fentanyl and weakest in groups where only thiopental was used. Blood pressure decreased in all groups but no statistically significant differences were noted. On the basis of the results it seems obvious that attempts to achieve what is called "balanced anaesthesia" by the supplementation of an N2O+O2 mixture with fentanyl only leads to an unnecessarily prnounced respiratory depression, whereas supplementation with thiopental alone does not offer adequate antinociception.     

Propofol, but not thiopentone or etomidate, enhances isoflurane-induced coronary vasodilatation in dogs

PURPOSE: To test the hypothesis that thiopentone, propofol, and etomidate alter the coronary vascular effects of abruptly administered isoflurane. METHODS: Dogs (n = 6) received inspired isoflurane 5% in the presence of thiopentone (20 mg.kg-1 induction dose and 20 mg.kg-1.hr-1 infusion), propofol (5 mg.kg-1 induction dose and 40 mg.kg-1.hr-1 infusion), etomidate (2 mg.kg-1 induction dose and 5 mg.kg-1.hr-1 infusion), or isoflurane (1.0 MAC) anaesthesia in a random fashion. Haemodynamics were assessed in the conscious state, during baseline anaesthesia, and at 30 sec intervals for five minutes after beginning isoflurane 5%. RESULTS: Rapidly administered isoflurane caused greater (P < 0.05) reductions in coronary vascular resistance in thiopentone- or propofol--than in isoflurane-anaesthetized dogs. Isoflurane produced greater (P < 0.05) increases in the ratio of coronary blood flow velocity to pressure-work index (an index of myocardial oxygen consumption; +109 +/- 19% during isoflurane alone vs +182 +/- 27% change from baseline during propofol and isoflurane) consistent with relatively greater direct coronary vasodilatation during baseline propofol than during baseline isoflurane anaesthesia. Isoflurane caused larger increases in coronary blood flow velocity in dogs anaesthetized with etomidate concomitant with higher coronary perfusion pressure and pressure-work index than in those anaesthetized with isoflurane alone. CONCLUSIONS: The results suggest that thiopentone, propofol, and etomidate each uniquely modify the coronary vascular responses to abrupt administration of high inspired concentrations of isoflurane in chronically instrumented dogs.     

Attenuation of the haemodynamic responses to noxious stimuli in patients undergoing cataract surgery. A comparison of magnesium sulphate, esmolol, lignocaine, nitroglycerine and placebo given i.v. with induction of anaesthesia

A study was conducted on 100 middle-aged to elderly patients (n = 52, healthy; n = 48, suffering from either diabetes, hypertension, ischaemic heart disease or a combination of these diseases) undergoing cataract extraction to assess the effects of laryngoscopy and tracheal intubation, anaesthesia and surgery, eye bandaging and tracheal extubation, saline (control), magnesium sulphate 40 mg kg-1, esmolol 4.0 mg kg-1, lignocaine 1.5 mg kg-1 and glyceryl trinitrate 7.5 micrograms kg-1 given i.v. at induction of anaesthesia on heart rate (HR), blood pressure (BP), rate-pressure product (RPP) and pressure-rate quotient (PRQ). Anaesthesia was standardized. Haemodynamic responses and requirements for atropine, ephedrine and labetalol to maintain HR and BP during surgery were similar in healthy and diseased patients, and in the test drug groups. Differences produced by the test drugs were evident until 5 min following intubation. Esmolol prevented rises in HR and RPP. Glyceryl trinitrate prevented a rise in BP, but was associated with tachycardia and a fall in PRQ to < 1.0. Magnesium sulphate and lignocaine did not prevent responses to laryngoscopy and tracheal intubation, and were associated with rises in RPP. Application of the eye dressing and tracheal extubation at the end of surgery each caused significant increases in HR, BP and RPP in all groups.