Hemodynamic and ventilatory responses to fentanyl, fentanyl-droperidol, and nitrous oxide in patients with acquired valvular heart disease

Noradrenergic Mechanisms in Fentanyl-Mediated Rapid Death Explain Failure of Naloxone in the Opioid Crisis

In December 2018, the Centers for Disease Control declared fentanyl the deadliest drug in America. Opioid overdose is the single greatest cause of death in the United States adult population (ages 18-50), and fentanyl and its analogs [fentanyl/fentanyl analogs (F/FAs)] are currently involved in >50% of these deaths. Anesthesiologists in the United States were introduced to fentanyl in the early 1970s when it revolutionized surgical anesthesia by combining profound analgesia with hemodynamic stability. However, they quickly had to master its unique side effect. F/FAs can produce profound rigidity in the diaphragm, chest wall and upper airway within an extremely narrow dosing range. This clinical effect was called wooden chest syndrome (WCS) by anesthesiologists and is not commonly known outside of anesthesiology or to clinicians or researchers in addiction research/medicine. WCS is almost routinely fatal without expert airway management. This review provides relevant clinical human pharmacology and animal data demonstrating that the significant increase in the number of F/FA-induced deaths may involve α-adrenergic and cholinergic receptor-mediated mechanical failure of the respiratory and cardiovascular systems with rapid development of rigidity and airway closure. Although morphine and its prodrug, heroin, can cause mild rigidity in abdominal muscles at high doses, neither presents with the distinct and rapid respiratory failure seen with F/FA-induced WCS, separating F/FA overdose from the slower onset of respiratory depression caused by morphine-derived alkaloids. This distinction has significant consequences for the design and implementation of new pharmacologic strategies to effectively prevent F/FA-induced death. SIGNIFICANCE STATEMENT: Deaths from fentanyl and F/FAs are increasing in spite of availability and awareness of the opioid reversal drug naloxone. This article reviews literature suggesting that naloxone may be ineffective against centrally mediated noradrenergic and cholinergic effects of F/FAs, which clinically manifest as severe muscle rigidity and airway compromise (e.g., wooden chest syndrome) that is rapid and distinct from respiratory depression seen with morphine-derived alkaloids. A physiologic model is proposed and implications for new drug development and treatment are discussed.

Plasma levels of glucose, insulin and cortisol in children undergoing cardiac surgery: effects of pulsatile and nonpulsatile perfusion

The effects of pulsatile and nonpulsatile perfusion on the plasma glucose, insulin and cortisol levels were studied in 12 children undergoing intracardiac repair of congenital heart defects. Hyperglycaemia was noted in both subgroups during the operation but plasma glucose returned to normal levels at 24 hours. Insulin secretion was suppressed during the period of extracorporeal circulation (ECC) and this was pronounced while the aorta was crossclamped. Cortisol levels were elevated during the whole period of study and remained elevated at 24 hours. In the pulsatile group cortisol levels were higher than the nonpulsatile group. However there was no significant difference between the groups.

Like adults, children exhibit a metabolic response during open-heart operations. Pulsatile perfusion delivered by a modified Stöckert roller pump during ECC, did not alter the glucose, insulin and cortisol response to cardiac surgery in this study.

Early extubation after cardiac surgery using combined intrathecal sufentanil and morphine

The records of 10 patients who had well-preserved respiratory and ventricular function and had received 50 micrograms of sufentanil and 0.5 mg of morphine intrathecally before induction of anesthesia for cardiopulmonary bypass surgery were reviewed. Anesthesia was maintained with isoflurane and no patient received intravenous narcotics intraoperatively. Postoperative analgesic requirements were low, with 7 of 10 patients requiring no supplemental analgesic during the first 12 hours. Early extubation (within 8 hours of arrival in the intensive care unit) was possible in 8 patients; two patients remained intubated for reasons unrelated to the anesthetic technique. No patient required naloxone, reintubation, or treatment for respiratory depression. Combined intrathecal sufentanil and morphine provided conditions that allowed successful early extubation in 8 of 10 of these selected cardiac surgery patients.

Delivery of constant air-oxygen mixtures using a closed circle absorber system

The aim of this study was to devise and validate a technique to deliver constant air-oxygen mixtures from a standard anaesthetic machine using only oxygen as the compressed gas source. The common gas outlet was modified to allow measured quantities of ambient air to be insufflated via a three-way attachment into a closed circle absorber system with a double-circuit collapsible bellows ventilator. During positive pressure ventilation, leakages of between 50-150 ml.min-1 occur from the circuit and nomograms of the minimal air and oxygen flow rates needed to maintain constant oxygen concentrations in the presence of the leaks were then mathematically derived. The accuracy of the nomograms was tested on three different anaesthetic machines using test lung models. There were no differences observed among the mean oxygen concentrations using the three machines. Pooled mean values (SD) of 30.65% (0.77), 51.07% (1.04) and 70.4% (0.73) were obtained for predicted inspired concentrations of 30, 50 and 70% respectively. Next, the technique was studied on 18 patients who underwent isoflurane or propofol anaesthesia (duration 40-210 min) for various surgical procedures. Pooled mean values (SD) obtained were 29.3% (1.86), 40.95% (1.65) and 50.06% (1.41) respectively for predicted oxygen concentrations of 30, 40 and 50% respectively. We conclude that this technique can be used to deliver constant air-oxygen mixtures accurately during inhalational or total intravenous anaesthesia when N2O is contraindicated but a source of compressed air is not readily available.

Effects of fentanyl on coronary blood flow distribution and myocardial oxygen consumption in the dog

Little data exist on the effects of fentanyl on coronary blood flow (CBF), myocardial oxygen balance, and the regional distribution of blood flow. These studies were designed to determine whether fentanyl had any intrinsic effects on myocardial oxygen consumption (MVO2) and blood flow distribution. In anesthetized dogs, fentanyl was administered in a dose of 50 micrograms/kg and various measurements were made at 5 and 20 minutes. After hemodynamic recovery from the fentanyl, the animals were treated with atropine to block the known vagomimetic effect of fentanyl and challenged with acetylcholine (3.5 micrograms/kg); then fentanyl (50 micrograms/kg) was again administered and measurements made at 5 and 20 minutes. In the untreated dogs at 5 minutes post-fentanyl, heart rate (HR) decreased 30% and at 20 minutes decreased 29%. Treatment with atropine essentially eliminated HR changes at both time periods. Mean arterial pressure (MAP) fell by 20% and 22% at 5 minutes and 20 minutes, respectively, in the untreated group, but when atropine was administered, MAP was observed to be intermediate between baseline and the untreated animals. Left ventricular MVO2 at 5 minutes in the untreated group was modestly but not significantly reduced. However, at 20 minutes post-fentanyl, MVO2 decreased significantly. MVO2 was essentially unchanged after atropine. Regional CBF (measured by radiolabelled microspheres) was unchanged at 5 minutes, but all layers exhibited significant reductions at 20 minutes. In the atropine group, only the LV epicardial area appeared to show decreases in flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Haemodynamic responses to tracheal intubation following etomidate and fentanyl for anaesthetic induction

The haemodynamic response to anaesthetic induction and tracheal intubation was studied in 29 patients undergoing elective myocardial revascularization surgery. All patients included in the study were anaesthetized with etomidate, 0.3 mg.kg-1. The patients were randomized to three groups: Group I received fentanyl, 2.5 micrograms.kg-1; Group II received fentanyl, 5 micrograms.kg-1; and Group III received fentanyl, 10 micrograms.kg-1. Haemodynamic variables were measured at baseline (awake), after anaesthetic induction, and at one, three, five, and ten minutes after tracheal intubation. The number of patients with haemodynamic responses to intubation (> 20% increase in heart rate or mean arterial pressure) was greater (P < 0.05) in Group I than in Groups II and III. Statistically significant, but clinically minor, decreases in mean arterial pressure and cardiac output occurred in all groups at the last three study times. The frequency of involuntary muscle movements was 14%, and all of these events occurred in patients in Group I. In conclusion, the authors recommend using fentanyl, 5-10 micrograms.kg-1 to blunt the haemodynamic response to tracheal intubation following anaesthetic induction with etomidate, 0.3 mg.kg-1.

Cardiovascular effects of pancuronium, vecuronium, and atracurium during induction of anesthesia with sufentanil and lorazepam for myocardial revascularization

The hemodynamic effects of three commonly used muscle relaxants, pancuronium, vecuronium, and atracurium were investigated during induction of anesthesia with sufentanil and lorazepam in patients undergoing coronary artery bypass surgery. Direct hemodynamic variables were recorded, and indirect parameters were calculated using standard formulae. Changes in heart rate differed with the three muscle relaxants. Pancuronium increased the heart rate whereas vecuronium and atracurium produced a decrease 5 minutes after induction (P less than 0.05). No differences were found in any other parameter during the study. A slow induction with sufentanil, lorazepam, and any of the three muscle relaxants was shown to minimize the hemodynamic changes.

Attenuated sympathetic tone augments nitrous oxide-induced myocardial depression during high-dose fentanyl anaesthesia in dogs

The purpose of this study was to determine whether centrally mediated sympathetic tone exerts compensatory effects on nitrous oxide-induced myocardial depression during high-dose fentanyl anaesthesia. The cardiovascular responses to 60 minutes of nitrous oxide administration after fentanyl, 100 micrograms.kg-1, were examined in 18 dogs with or without autonomic blockade induced by hexamethonium. Decreases of cardiac output and left ventricular stroke work were significantly greater in dogs with autonomic blockade (n = 9) by about 20 per cent of baseline values than in dogs without autonomic blockade (n = 9) at 30, 45, and 60 min. Similarly, left ventricular dP/dt was reduced more in dogs with autonomic blockade than in dogs without autonomic blockade, but this difference was only significant at the 60-min period. It is concluded that the sympathetic nervous system provides partial compensation for myocardial depression induced by nitrous oxide in the presence of high-dose fentanyl, suggesting that large doses of fentanyl do not ablate the centrally mediated sympathomimetic effects of nitrous oxide.

Opiate anaesthesia

Current use of opioids in anaesthesia is reviewed with particular emphasis on the use of opioids in anaesthetic doses, techniques that recently have become popular in cardiovascular anaesthesia. A major benefit of opioid anaesthesia (particularly fentanyl) is the cardiovascular stability which obtains during induction and throughout operation, even in patients with severely impaired cardiac function. Anaesthetic doses of morphine are associated with a higher incidence of cardiovascular disturbances and other problems. Pethidine is unsuitable for cardiovascular surgery because of severe haemodynamic disturbances when high doses are given. Sufentanil and alfentanil may prove more suitable alternatives. High doses of opioids can reduce or prevent hormonal and metabolic responses to the stress of surgery. Even very large doses of fentanyl or its new analogues do not prevent marked increases in plasma catecholamine concentrations in response to cardiopulmonary bypass. The reduction in hormonal and metabolic stress response does not appear to continue postoperatively.

Selective tolerance of group III and IV somatosympathetic reflexes to the effects of alfentanil

The effect of alfentanil on responses in renal sympathetic nerves evoked by supramaximal electrical stimulation of the radial nerve, has been observed in 6 dogs anaesthesized with alpha-chloralose, paralysed with suxamethonium and ventilated artificially. During an initial infusion of alfentanil the responses of the late group IV (C fibre) and early group III (A delta) were abolished by mean doses of 68 micrograms kg-1 (SEM 3.2 micrograms kg-1) and 797 micrograms kg-1 (SEM 120 micrograms kg-1), respectively. Recovery was allowed to occur to approximately 50% of control values (mean time 76 +/- 14.3 min). The preparations were then conditioned with 7 incremental doses from 7.5 to 120 micrograms kg-1 (i.v.) (total dose 308.5 micrograms kg-1), administered at intervals of 10 min, and subsequently tested with large bolus doses (up to 2000 micrograms kg-1) of alfentanil. In two preparations, the responses of both group IV and group III became completely tolerant to the effects of alfentanil while in the other four the response of the group IV was still eliminated by the drug and the response of group III showed selective tolerance. The heart rate and arterial pressure were reduced by 45 and 29%, respectively during the initial infusion of alfentanil. Thereafter there were no further significant changes in the circulation until the administration of naloxone (2 mg i.v.), which restored the sympathetic responses, heart rate and arterial pressure to control values.

Recurrence of pulsus alternans after fentanyl injection in a patient with aortic stenosis and congestive heart failure

Following aortic valve replacement in a patient with aortic stenosis and cardiac failure, marked pulsus alternans recurred immediately after intravenous injection of 0.5 mg fentanyl, without concomitant changes in heart rate, mean left atrial pressure, or the electrocardiogram. Pulsus alternans is known to occur in association with heart failure and aortic stenosis, but has not been reported previously in response to anaesthetic drugs. Mechanisms of pulsus alternans are discussed, and the possible contributory role of fentanyl is considered.

Haemodynamic stability during anaesthesia induction and sternotomy in patients with ischaemic heart disease. A comparison of six anaesthetic techniques

A comparison of haemodynamic stability with respect to arterial pressure, heart rate and cardiac output between six commonly used anaesthetic techniques: fentanyl (FE), halothane (HAL), morphine (MO), fentanyl/droperidol (NLA), and thiopentone (two dose levels: PE 3 and PE 6), all supplemented with nitrous oxide, was performed during induction of anaesthesia and sternotomy in 47 patients with good left ventricular function and maintained beta-blockers undergoing coronary bypass surgery. Interventions were kept to a minimum in order to characterize each anaesthesia group. Statistically, the material fell into two parts. The MO, PE 3 and PE 6 groups showed good stability under steady-state anaesthesia, but variable and often extensive hyperdynamic responses were seen to endotracheal intubation and surgical stimulation. The FE, HAL and NLA groups were characterized by a good stability during the induction-intubation phase but were unstable when combined with nitrous oxide in the absence of noxious stimuli.

Haemodynamic response to nitrous oxide during high-dose fentanyl pancuronium anaesthesia

Ten patients subjected to coronary by-pass surgery were studied to determine the haemodynamic effects of replacing Fio2 1.0 normoventilation with nitrous oxide in oxygen (Fio2 0.3) after induction of anaesthesia with fentanyl (50 micrograms/kg), flunitrazepam and pancuronium. In all patients the application of N2O decreased systemic arterial pressures by an average of 10% (P less than 0.001), but left pulmonary arterial pressures and systemic vascular resistance unchanged. The slight bradycardia induced was associated with moderate depression of the cardiac index and the left ventricular stroke work index (P less than 0.001) at the time when the rate-pressure product was decreased by 20% (P less than 0.001). The cardiac depression produced by N2O was most prominent in patients with left ventricular wall hypokinesia and an ejection fraction below 55%, in whom the cardiac work index was diminished by 29%. The replacement of oxygen with nitrous oxide in oxygen during high-dose fentanyl-pancuronium anaesthesia seems not to be associated with sympathetic stimulation, and the myocardial depressant effect of N2O should be weighed against the possible reduction in myocardial oxygen consumption with special care in patients with compromised myocardial function.

Administration of sulmazol in low-output states following cardiac surgery

Sulmazol (AR-L 115BS), a phenylimidazopyridine derivative, which combines positive inotropic and vasodilating properties, was administered to nine patients who had a low cardiac output state (cardiac index below 2.0 L/min/m2) within 24 hours after cardiac surgery for valvular replacement (eight patients) or septal repair after myocardial infarction (one patient). Sulmazol, administered as a 60-minute infusion of 1.8 mg/min, resulted in significant increases in cardiac output and cardiac work, associated with significant decreases in cardiac filling pressures. Arterial pressure did not change notably, and systemic vascular resistance decreased significantly. A small but significant increase in heart rate was also observed. By its combined inotropic and vasodilating properties, sulmazol can be helpful in the management of low-output states after cardiac surgery.

Selective effect of fentanyl on group III and IV somatosympathetic reflexes

The effect of fentanyl on sympathetic reflexes evoked by supramaximal electrical stimulation of the radial nerve, and the subsequent reversal of its effects by naloxone, have been observed in 10 dogs anaesthetized with alpha-chloralose, paralysed with suxamethonium and artificially ventilated. During infusions of 5 micrograms kg-1 min-1 the late, long-latency, sympathetic response evoked by unmyelinated fibres was abolished at a mean dose of 27 micrograms kg-1 (SD 12.6 micrograms kg-1) after which the early, short-latency response evoked by small myelinated fibres was eliminated at a mean dose of 90.3 micrograms kg-1 (SD 54.6 micrograms kg-1) so that there was no longer any response to stimulation of the radial nerve. During a subsequent infusion of naloxone (200 micrograms min-1) the late response returned to control values at a mean dose of 0.5 mg and subsequently the early response reappeared to return to control values at a total dose of 1.6 mg. In 2 preparations phrenic nerve activity was abolished after 6.1 and 17.4 micrograms kg-1 of fentanyl and returned immediately before the late response, during the infusion of naloxone. In 2 preparations, induced tolerance occurred so that the early response could not be eliminated.

Effect of combinations of topical anaesthesia, fentanyl, halothane or N2O on circulatory intubation response in normo- and hypertensive patients

Attenuation of the circulatory intubation response was studied using the following combinations: oropharyngeal topical anaesthesia (OTA) + fentanyl 2 micrograms/kg (F2), OTA + 2% halothane with 70% nitrous oxide (H2N2O) or F2 + H2N2O. Firstly, it was observed in 48 normotensive patients that the combinations of OTA + F2 or F2 + H2N2O totally prevented the intubation response; OTA + H2N2O, on the other hand, was less effective. Secondly, the effect of OTA + F2 was studied in 26 hypertensive patients and their 26 normotensive controls of the same age group. The combination prevented the circulatory intubation response also in the hypertensive patients, whose circulatory reactions did not differ from those of the normotensive patients. Nitrous oxide had no beneficial effect on the intubation response.

Comparison of haemodynamic effects of morphine and fentanyl in patients with coronary artery disease

The haemodynamic effects of morphine (2.5 mg kg-1) and fentanyl (16.7 and 25 micrograms kg-1) were compared in patients undergoing coronary artery bypass surgery. Morphine or fentanyl in combination with pancuronium, nitrous oxide and a small dose of thiopentone produced some deterioration of myocardial performance. Both analgesics failed to block haemodynamic responses to noxious stimulation including tracheal intubation and sternotomy. Heart rate increased following tracheal intubation and systemic vascular resistance increased after sternotomy. However, the larger dose of fentanyl (25 micrograms kg-1) was accompanied by the smallest haemodynamic changes. Supplementary anaesthetic agents were often required to maintain haemodynamic stability during sternotomy. It is suggested here that larger doses of fentanyl, or the addition of other intravenous or inhalation anaesthetics might be employed for patients with severe coronary artery disease and good left ventricular function. On the other hand, in patients with poor left ventricular function, the myocardial depressant properties of thiopentone and nitrous oxide may be detrimental.

Haemodynamic effects of calcium chloride administered intravenously to patients with and without cardiac disease during neurolept anaesthesia

During neurolept anaesthesia, calcium chloride (15 mg/kg) was administered intravenously to two different groups of patients undergoing vascular surgery on the abdominal aorta. The patients in group I all suffered from cardiac disease and were treated with digoxin, while the patients in group II had no cardiac symptoms. Cardiovascular measurements were made during steady-state anaesthesia. In group I, CaCl2 increased cardiac index (CI) significantly while systemic vascular resistance index (SVRI) remained unchanged. Mean arterial pressure (MAP) increased. In group II, both MAP and SVRI increased while CI remained unchanged. No significant changes in heart rate were observed and no arrhythmias occurred. It is concluded that CaCl2 administered intravenously is an effective means of improving cardiac function when it is depressed by anaesthesia, underlying cardiac disease, or both.

[Comparison of the hemodynamic effects of midazolam-fentanyl and thiopental-fentanyl combinations in the induction of general anesthesia]

The hemodynamic changes during anesthetic induction for elective abdominal aortic surgery were studied in two groups of patients. Group M (9 patients) received midazolam 0.3 mg . kg-1 and fentanyl 6 micrograms . kg-1. Group T (10 patients) received thiopentone 6 mg . kg-1 and fentanyl 5 micrograms . kg-1. The radial and pulmonary arteries were catheterized under local anesthesia. An intravenous infusion was administered in order to normalize pulmonary wedge pressure. Systemic and pulmonary arterial pressures, pulmonary wedge pressure, cardiac output and heart rate were measured after the infusion and 5 min after intubation. Mean arterial pressure showed a statistically significant reduction in both groups. Cardiac index remained unchanged in group M, but was significantly diminished in group T. There was no significant reduction in the systemic vascular resistance index for group M, but group T showed a statistically significant increase. This study confirmed the good hemodynamic tolerance of the midazolam induction technique, even with a high dose of 0.3 mg . kg-1.

Nitrous oxide added to halothane reduces coronary flow and myocardial oxygen consumption in patients with coronary disease

The haemodynamic and myocardial metabolic effects of adding 50 per cent nitrous oxide to 0.5 per cent halothane were studied in 13 patients, before the surgical incision for coronary artery vein grafts. Cardiac output and coronary sinus blood flow were determined by thermodilution, along with haemodynamic measurements. Measurements 15 minutes after addition of nitrous oxide revealed a significant decrease in heart rate, arterial pressure, cardiac index, coronary sinus blood flow and myocardial oxygen consumption. There was a significant increase in coronary sinus lactate content, and a significant decrease, from 27 to 11 per cent, in myocardial lactate extraction. We conclude that these circulatory changes were likely to be due to a depression of ventricular function by the nitrous oxide. The myocardia of these patients with severe coronary disease were becoming globally ischaemic while they were receiving 50 per cent oxygen, in the presence of hypotension. Nitrous oxide should be turned off when hypotension occurs in coronary patients.

Attenuation of the circulatory response to laryngoscopy and intubation by fentanyl

The effects of fentanyl on arterial pressure and heart rate increases during laryngoscopy and intubation were studied in 45 normotensive, surgical patients, who were randomly allocated to three groups receiving 2 or 6 micrograms/kg of fentanyl or saline in a double-blind fashion before anaesthetic induction with thiopental. Fentanyl supplementation with 2 micrograms/kg significantly attenuated the arterial pressure and heart rate increases during laryngoscopy and intubation, and fentanyl, 6 micrograms/kg, completely abolished these responses. Moreover, fentanyl given during the induction decreased the amount of fentanyl needed during the operation. Respiratory depression was not observed during recovery.

Comparative clinical study of pulsatile and non-pulsatile perfusion in 350 consecutive patients

Pulsatile perfusion has been shown to offer significant haemodynamic advantages over non-pulsatile perfusion in many experimental studies. Clinical acceptance of pulsatile perfusion during cardiac surgical procedures has, however, been hampered by the lack of technologically satisfactory pulsatile pump systems, and by inadequate clinical experience of routine use of pulsatile perfusion. The recent introduction of reliable pulsatile pump systems with low haemolysis characteristics has made possible the clinical validation of the previous experimental studies. We describe the results of a prospective study of mortality, haemodynamic morbidity, and haematological status, in 350 consecutive adult patients submitted to cardiopulmonary bypass procedures in a surgical unit over a 12-month period. One hundred and seventy five patients were perfused with conventional non-pulsatile flow and 175 with pulsatile flow, using a modified roller-pump pulsatile system (Cobe-Stockert). The groups were closely similar in terms of preoperative characteristics, referral category, and pathology requiring surgery. Operative techniques, bypass parameters, and anaesthetic regime were standardised in both groups. The results were as follows. (1) Total mortality was significantly lower in the pulsatile group (4.6%) compared with the non-pulsatile group (10.3%), p = 0.06. (2) The incidence of deaths attributable to post-perfusion low cardiac output was significantly lower in the pulsatile group (1.1% compared with 6.3%, p = 0.02). (3) Requirement for mechanical (intra-aortic balloon) or drug circulatory support was significantly lower in the pulsatile group. (4) The use of pulsatile perfusion was not associated with any increase in haemolysis, blood cell depletion, or postoperative bleeding problems.

[Hemodynamic and hormonal study of electronarcosis and neuroleptanalgesia. Clinical study in 17 surgical patients]

The blocking effect of electropharmaceutical anesthesia (EPA) and neuroleptanalgesia (NLA) on adrenergic and hormonal reactions to abdominal surgery were compared in 17 ASA class I to III randomized patients. This study was intended to define the indications for each of these techniques in patients with heart diseases. Each individual received the same anesthetic premedication and induction and was submitted to iterative identical measurements and biological dosages. Before and during surgery, both groups were catheterized with a Swan-Ganz and a radial catheter. Blood sampling for catecholamines, cortisol, glycemia, blood gases dosages were regularly drawn. Electrical stimulation was performed in the EPA group, and fentanyl injections were repeated in the NLA group patients only. The same doses of pancuronium and droperidol were given to every patient. A circulatory hyperkinesia and hyperadrenergia were observed during surgery in all of the subjects but, during EPA, the tachycardia, the cardiac index and the rate-pressure product were higher than during NLA. The body temperature increased towards normal in EPA, not in NLA. Adrenergic and hormonal levels were equal in both groups. The slow variations of all the important parameters demonstrate that the measured phenomenons have a long time-course what legitimates this kind of prolonged on-the-spot observation. The role of droperidol, pancuronium and fentanyl in the observed variations is discussed. The characteristic high hyperkinesia in EPA may be due partly to an inefficacious analgesia because of the fentanyl suppression after induction, partly to the preserved thermogenesis partly to a direct effect of the electrical stimulation on cerebral tissues.

Neuroleptanalgesia in acute myocardial infarction: effects of hemodynamic parameters and plasma catecholamines

The use of neuroleptanalgesia in acute myocardial infarction offers the possibility of reducing pain and emotional stress. The influence of such treatment on hemodynamic parameters (heart rate, cardiac output, stroke volume, peripheral resistance, systemic blood pressure, and pulmonary pressure) and on the plasma level of adrenaline and noradrenaline has been studied in 6 patients with acute myocardial infarction. This results demonstrate that during neuroleptanalgesia the already elevated levels of noradrenaline and adrenaline further increase. This increase was most pronounced in the patients with the highest initial levels of catecholamines. Since the peripheral resistance and systolic and diastolic blood pressures decrease concomitantly, it is concluded that the increase in levels of noradrenaline and adrenaline further increase. This increase was most pronounced in the plasma catecholamines is due to a reaction of the sympathetic nervous system to the alpha-adrenergic receptor blocking activity of droperidol causing vasodilation. The data indicate that pain, emotional stress, and anxiety in the acute phase of myocardial infarction do not play the expected essential role for the activation of the sympathetic nervous system generally observed in acute myocardial infarction. Additionally, the data demonstrate that drugs producing a vasodilation can have a deteriorating effect on the hemodynamic situation and that a reduction of the afterload by vasodilating drugs can result in a further increase in the release of catecholamines.

Myocardial oxygen consumption and coronary haemodynamics during fentanyl-droperidol-nitrous oxide anaesthesia in patients with ischaemic heart disease

Eight patients with stable ischaemic heart disease were investigated to determine the effects of fentanyl (15 micrograms/kg) - droperidol (150 micrograms/kg) - nitrous oxide (75%) anaesthesia, without concomitant fluid challenge, on myocardial oxygen consumption and lactate uptake, and central and coronary haemodynamics. Anaesthesia induced reductions in mean arterial pressure (--35%, P less than 0.01), systemic vascular resistance (--30%, P less than 0.01), left ventricular stroke work index (--50%, P less than 0.01) and total body oxygen consumption (--23%, P less than 0.01), with no changes in heart rate, cardiac output or mean pulmonary arteriolar occlusion pressure. Mixed venous oxygen content increased (P less than 0.05). Systemic vasodilatation, circulatory adaptation to an overall lower metabolic rate, and clinically negligible cardiodepression are the likely mechanisms behind the central haemodynamic response to this form of anaesthesia. Coronary sinus blood flow (measured by the continuous thermodilution technique) decreased (P less than 0.01) in parallel with the decrease in coronary perfusion pressure. Thus coronary vascular resistance remained unchanged. As expected from the haemodynamic findings, myocardial oxygen consumption decreased (--37%, P less than 0.01). Coronary sinus oxygen content and myocardial oxygen extraction did not change, nor was myocardial lactate uptake affected. No ST-T-segment depressions or dysrhythmias were recorded. These observations indicate that myocardial oxygenation was adequate in spite of the reduction in coronary perfusion pressure. There was poor correlation between changes in myocardial oxygen consumption and rate pressure product (R = 0.455) or triple produce (R - 0.375).

Early response in central hemodynamics to high doses of sufentanil or morphine in dogs

The hemodynamic effects of high doses of sufentanil, a newly synthetized highly potent analgesic, were investigated in dogs. This study compared the early (30 min) cardiovascular effects of sufentanil 0.01 mg . kg-1 and morphine 4 mg . kg-1. Sufentanil caused a moderate and insignificant decrease in mean arterial pressure (MAP). A 30% decrease in cardiac index (CI) was almost outbalanced by an increased systemic vascular resistance (SVRI). The lowering of CI was due to a more than 50% decrease in heart rate (HR) which was partly compensated for by a greater stroke volume index (SVI). In the first 5 min after morphine injection, MAP fell significantly to about 50 mmHg (below 50% of the control value). CI was reduced to about 50% of the control value because of significant decreases in both SVI and HR. The calculated SVRI was unchanged after morphine. Within 30 min some of the initially changed parameters had returned to control levels. Central venous pressure (CVP) and pulmonary capillary wedge pressure (PCWP) increased immediately after sufentanil, but decreased after morphine. With time, both parameters returned towards control values. Peak left ventricular dP/dt decreased by about 25-50% after both analgesics. The rate-pressure products (RPP) were significantly decreased to less than one half of the control values after both analgesics. Mixed venous oxygen tension (PVO2), oxygen transport and oxygen consumption were significantly lowered in the sufentanil group, whereas immediate decreases after morphine were followed by gradual increases towards control values. We conclude that the use of high doses of sufentanil in dogs is safe. Apart from initial, transient changes, a stable cardiovascular state characterizes the high-dose sufentanil anesthesia, while morphine causes fluctuations in several hemodynamic parameters. Compared to morphine anesthesia, sufentanil anesthesia appears to be an attractive alternative which deserves further evaluation in humans.

Hemodynamic observations in evacuation of molar pregnancy

The high incidence of pulmonary complications following evacuation of molar gestation at 16 weeks' size of greater (27%) prompted us to institute hemodynamic monitoring in seven of these patients in an effort to determine etiologies and possible modes of therapy for this potentially life-threatening complication. Our data indicate that following suction curettage with general anesthesia there appears to be impairment of ventricular performance of a transient nature as manifested by increases in central venous pressure, mean pulmonary artery pressure, and pulmonary capillary wedge pressure, despite a slight elevation in cardiac index and a decrease in systemic vascular resistance. The possible role of general anesthesia in the development of these changes, as well as the role of the colloid osmotic pressure to wedge gradient in the development of pulmonary complications, is discussed.

Effects of nitrous oxide on systolic time intervals

The effects of inhalation of oxygen, nitrous oxide/oxygen and nitrous oxide/nitrogen/oxygen on systolic time intervals (PEP (pre-ejection period) and LVET (left ventricular ejection time) were investigated in eight healthy persons. Nitrous oxide 40%, administered with oxygen or oxygen/nitrogen, prolonged PEP significantly by 25% and 22%, respectively. Inhalation of oxygen also prolonged PEP but to a significantly minor degree. LVET, heart rate and MAP were unchanged during the experiments. Derivatives from the systolic time intervals, i.e. PEP/LVET, I/PEP2 and ejection fraction changed significantly in the nitrous oxide groups. It is concluded that nitrous oxide depresses cardiac performance, to some degree, even when administered at a rather low concentration.

Cardiovascular effects of neurolept anaesthesia in patients with coronary artery disease

An anaesthetic technique comprising a combination of phenoperidine (0.1 mg . kg-1), diazepam (0.06 mg . kg-1) and pancuronium bromide (0.1 mg . kg-1) with controlled ventilation was evaluated in 12 patients with severe coronary artery disease. The heart rate, cardiac output and mean arterial blood pressure did not change significantly between the preinduction and postinduction measurements. The right atrial pressure and pulmonary capillary wedge pressure decreased significantly by 33% and 36%, respectively, probably due to the influence of positive-pressure ventilation. There was no depression of the left ventricular performance.

Effects of neurolept anaesthesia (NLA) on haemodynamics and oxygen consumption in the dog with special reference to the liver and preportal tissues

The effects of neurolept anaesthesia (NLA) on central circulation, total oxygen uptake and splanchnic circulation and oxygen uptake were studied in 12 artificially ventilated dogs, basally anaesthetized with thiopental and nitrous oxide. Hepatic arterial, superior mesenteric arterial and portal venous blood flows were measured with electromagnetic flowmetry. Cardiac output was measured by thermodilution. Determinations of oxygen contents were made in arterial, pulmonary arterial, portal venous and hepatic venous blood. NLA was induced with droperidol 0.5 mg . kg-1 b.w. and fentanyl 0.01 mg . kg-1 b.w. Arterial blood pressure decreased to 63% of control value due to reductions of cardiac output to 78% and of total peripheral vascular resistance to 81% of control values. Hepatic arterial, superior mesenteric arterial and portal venous blood flows all diminished to 75% of control values. Hepatic arterial, superior mesenteric arterial and preportal tissue vascular resistances all decreased. Total oxygen uptake declined to the same extent as cardiac output, leaving the arterio-venous oxygen difference unchanged. Oxygen uptake of the preportal tissues was unaffected and hepatic oxygen uptake was not significantly reduced, although there were decreases of hepatic oxygen uptake in some of the individual dogs. It is suggested that the cardiovascular depression following NLA was due to adaptation to a lowered total oxygen uptake. It is further concluded that splanchnic circulation was well preserved due to decreases in splanchnic vascular resistances, and that splanchnic oxygen consumption was maintained by means of increased oxygen extraction.

The effect of propanidid on systemic vascular resistance in man

We have studied the peripheral vascular effect in man of propanidid 6 mg/kg, administered as a bolus injection during cardiopulmonary by-pass with the aorta cross-clamped and at constant perfusion flow. Ten measurements in eight patients were performed. A decrease was found in systemic vascular resistance: from 150.7 +/- 16.3 to 99.5 +/- 10.1 kPa x s/1. No venous pooling occurred. It is concluded that, in man, propanidid causes a vasodilation which must contribute to the hypotension it causes.

Cardiovascular effects of local adrenaline infiltration during neurolept analgesia and adrenergic beta-receptor blockade in man

The adrenergic beta-receptor blocking drug, alprenolol, was given together with atropine to 15 patients during neurolept analgesia (NLA) in order to prevent adrenaline-induced cardiac arrhythmias. Four patients operated on without adrenergic beta-receptor blockade formed the control group. Three of them developed tachyarrhythmias, ventricular tachycardia, multifocal ventricular extrasystoles and supraventricular tachycardia. All these arrhythmias were terminated by the adrenergic beta-receptor blocking drug, propranolol. The fourth patient developed a temporary sinus tachycardia which did not require any treatment. The adrenergic beta-receptor blockade induced a slight increase in pulse rate with almost no change in arterial blood pressure. The incidence of arrhythmias due to adrenaline infiltration was much less in this group. There was one supraventricular tachycardia and scattered ventricular extrasystoles in two other patients. NLA alone does not protect the heart against adrenaline-induced arrhythmias. It does, however, seem to be compatible with an adrenergic beta-receptor blockade, which in turn provides partial protection against adrenaline-induced arrhythmias. The occasionally developing arrhythmias can then be terminated with specific adrenergic beta blockers.

The effect of surgical stress on haemodynamics during neurolept anaesthesia

The influence of surgical stress on haemodynamics during neurolept anaesthesia (NLA) was studied in ten patients, while they were awake, under anaesthesia prior to surgery and peroperatively. Systemic arterial, pulmonary arterial, right atrial and pulmonary capillary wedge pressures, as well as cardiac ouput (Qt), arterial oxygen content and mixed venous oxygen content, were measured. Systemic and pulmonary vascular resistances, arterial-venous oxygen content difference (AVD), oxygen consumption (VO2) and cardiac index (CI) were calculated. On institution of anaesthesia, CI fell from 2.8 +/- 0.1 1/min-m2 to 2.5 +/- 0.2 1/min-m2 and systolic arterial pressure (SBP) fell from 13.4 +/- 0.5 kPa to 10.2 +/- 0.3 kPa. During surgery CI rose to 3.3 +/- 0.1 1/min-m2 and SBP rose to 15.7 +/- 0.6 kPa. Prior to anaesthesia, AVD was 40.2 +/- 0.2 ml/l. Under anaesthesia prior to surgery, AVD did not change, but VO2 declined from 207 +/- 13ml/min to 171 +/- 10 ml/min. During surgery, AVD fell to 30.5 +/- 0.3 ml/l, while VO2 remained unchanged. It is concluded that NLA has a direct metabolic depressant effect and, in association with surgery, is accompanied by hyperkinetic circulation.

Cardiovascular effects of droperiodol during enflurane and enfluarne-nitrous oxide anaethesia in man

The cardiovascular effects of intravenous droperiodol 5 mg were measured in 20 patients during steady state enflurane-nitrous oxide-oxygen or enflurane-oxygen anaesthesia, droperiodol produced significant decreases in SVR and BP and increases in HR and Qt which were maximal after five minutes, somewhat less five minutes, somewhat less five minutes later, and back to control values 15 minutes after administration. SV was not significantly altered by droperiodol during enflurane-nitrous oxide-oxygen at any time after administration. During enflurane-oxygen anaesthesia droperidol reduced SVR and BP after five and ten minutes but did not significantly alter any other variable. All variables had returned to control levels 15 minutes after droperiodol during enfluarne-oxygen anaesthesia. These data demonstrate that droperidol produces a significant though transiet reduction of BP and SVR during enfluane anaesthesia which is associated with no change or an increase in Qt. Our findings suggest that droperidol causes minimal or no myocardial depression when used during potent inhalation anaesthesia and may have a place as an amnesic supplement and/or "afterload" reducer during light enflurance anaesthesia.

The cardiovascular effects of neuroleptanaesthesia

Oxygen uptake, cardiac output, stroke volume and arterial and central blood pressures were measured before and after induction of neuroleptanaesthesia in 27 subjects. Nine were elderly patients operated on for obliterative arteriosclerotic disease, and the other 18--nine elderly and nine younger patients--underwent operation for varicose veins. Cardiac output, stroke volume and systolic arterial blood pressure decreased significantly with a corresponding decrease in oxygen uptake. The changes were most pronounced in the patients with arteriosclerotic disease. The arterio-venous oxygen difference was unchanged in the arteriosclerotics and decreased in the other two groups. The central pressures remained unchanged in all groups. It is concluded that the cardiovascular changes induced by neuroleptanaesthesia are due to a decrease in oxygen uptake and not to myocardial depression.

The cardiovascular effects of diazepam and of diazepam and pancuronium during fentanyl and oxygen anaesthesia

The cardiovascular effects of diazepam 0.5 and 1.0 mg/kg and diazepam with pancuronium 0.1 mg/kg after fentanyl 0.5 mg/kg were determined in thirteen dogs premedicated with atropine. Fentanyl produced significant reductions in heart rate, cardiac ouptut and arterial blood pressure. Administration of 0.5 mg/kg of diazepam after fentanyl did not significantly alter stroke volume, arterial blood pressure or peripheral vascular resistance but did increase heart rate and cardiac output. Additional diazepam did not further change the heart rate, but did reduce stroke volume, cardiac output, arterial blood pressure and peripheral vascular resistance. Administration of pancuronium after fentanyl and diazepam produced marked elevations in heart rate, cardiac output and arterial blood pressure. There was no difference in mean heart rate and cardiac output when values prior to fentanyl and those obtained three minutes following pancuronium were compared. These data demonstrate that large doses of fentanyl decrease heart rate, cardiac these changes can be partially reversed with diazepam 0.5 mg/kg and completely antagonized with pancuronium 0.1 mg/kg.

The effects of large doses of fentanyl and fentanyl with nitrous oxide on renal function in the dog

Renal effects of large doses of fentanyl (1 mg/kg) were determined in 14 mongrel dogs before and after addition of 50 per cent nitrous oxide. Fentanyl significantly increased urine osmolarity and decreased urine output and free water clearance but did not change inulin or PAH clearances. The arterial blood pressure and cardiac output were significantly decreased after 0.1 mg/kg fentanyl and these changes were then maintained during the remainder of the study period. Addition of nitrous oxide produced no further changes in cardiac output and arterial blood pressure but did increase urine output, PAH, inulin and free water clearances and decreased urine osmolarity. These data demonstrate that high doses of fentanyl have significant antidiuretic properties in the dog and these probably are related to the release of antidiuretic hormone. Our results also indicate that addition of nitrous oxide reverses fentanyl induced antidiuresis.