Comparative effects of etomidate, ketamine, propofol, and fentanyl on myocardial contractility in dogs

PURPOSE

The present study was carried out to determine the direct effects of etomidate, ketamine, propofol, and fentanyl on myocardial contractility, and whether fentanyl would enhance the myocardial depression caused by propofol.

METHOD

The anesthetics were injected directly into the circuit that supplied blood to the left circumflex coronary artery (LCX) in anesthetized open-chest dogs. Myocardial contractility was evaluated from measurements of percent segmental shortening (%SS).

RESULTS

Etomidate, ketamine, and propofol significantly reduced %SS in a dose-dependent manner. The %SS values with 1.6 and 3.2 mg of etomidate were similar to those with 3.2 and 6.4 mg of ketamine, respectively, and the %SS value with 6.4 mg of propofol was similar to those with 3.2 and 6.4 mg of ketamine. Fentanyl alone had no effects on myocardial performance and did not influence the effect of propofol on %SS.

CONCLUSION

On the basis of clinical doses, the direct myocardial depressant effect of ketamine is more than twice as potent as that of etomidate and slightly more than that of propofol. Fentanyl has no inotropic effect and does not enhance the direct myocardial depressant effect of propofol.

Effects of sevoflurane with and without nitrous oxide on human cerebral circulation. Transcranial Doppler study

BACKGROUND

This study was designed to evaluate the effects of sevoflurane with and without nitrous oxide on human middle cerebral artery (MCA) flow velocity, cerebrovascular carbon dioxide reactivity, and autoregulation compared with the awake state using transcranial Doppler ultrasonography.

METHODS

In 14 patients, the time-mean middle cerebral artery flow velocity (Vmca) was measured when the end-tidal carbon dioxide level was approximately 30, 40, and 50 mmHg under the following conditions: (1) awake; (2) with 2% (1.2 MAC) sevoflurane; and (3) with 1.2 MAC sevoflurane-60% nitrous oxide. In six other patients, the cerebrovascular autoregulation during anesthesia was determined using intravenous phenylephrine to increase blood pressure.

RESULTS

Sevoflurane (1.2 MAC) significantly decreased Vmca compared with the awake value at each level of end-tidal carbon dioxide, whereas 1.2 MAC sevoflurane-60% nitrous oxide did not exert significant influence. The Vmca in normocapnic patients decreased from 69 cm/s to 55 cm/s with 1.2 MAC sevoflurane and then increased to 70 cm/s when nitrous oxide was added. Sevoflurane (1.2 MAC) with and without 60% nitrous oxide had a negligible effect on cerebrovascular carbon dioxide reactivity. A phenylephrine-induced increase of mean arterial pressure did not influence Vmca during anesthesia.

CONCLUSIONS

Sevoflurane (1.2 MAC) reduced Vmca compared with the awake condition, whereas the addition of nitrous oxide caused Vmca to increase toward the values obtained in the awake condition. The cerebrovascular carbon dioxide reactivity and autoregulation were well maintained during 1.2 MAC sevoflurane with and without 60% nitrous oxide.

Phosphatidylinositol responses are involved in the vascular effects of thiamylal and fentanyl

Although thiobarbiturates potentiate, and fentanyl attenuates peripheral vasoconstriction, the intracellular mechanism involved in this phenomenon is not clear. Because smooth muscle contraction induced by alpha 1-adrenoceptor agonists is mediated by the phosphatidylinositol (PI) response, this study was carried out to clarify if thiamylal and fentanyl affect the norepinephrine-induced PI response in rat aortic slices. Rat aortic slices were incubated in Krebs-Henseleit solution containing 5 mM LiCl, [3H]myo-inositol, and varying concentrations of thiamylal or fentanyl. The Pl response was stimulated by 0.9 microM (ED50) norepinephrine (NE). The [3H]inositol monophosphate (IP1) was separated from [3H]myo-inositol by column chromatography and counted with a liquid scintillation counter. The basal IP1 accumulation was not affected by thiamylal and fentanyl. Norepinephrine-induced IP1 accumulation was potentiated by thiamylal at concentrations of 10 microM and 100 microM. Norepinephrine-induced IP1 accumulation was attenuated by 1 microM and 10 microM fentanyl. The results suggest that thiamylal stimulates the NE-induced PI response, which potentiates the vasoconstriction, and fentanyl attenuates NE-induced PI response, which would attenuate the vasoconstriction.

A comparison of coronary hemodynamics during isoflurane and sevoflurane anesthesia in dogs

We studied the effects of sevoflurane and isoflurane on coronary hemodynamics in relation to myocardial oxygen supply and demand. Dogs were anesthetized with pentobarbital and fentanyl and received isoflurane or sevoflurane. An electromagnetic flow probe and a pair of piezoelectric crystals were placed on the left circumflex coronary artery (CX) to measure CX flow and diameter. The dogs were randomly assigned to receive isoflurane or sevoflurane at a dose of 0.75 and 1.5 minimum alveolar anesthetic concentration (MAC). The CX diameter decreased in parallel with the decrease in mean arterial pressure during both anesthetics. The CX blood flow decreased in parallel with the decrease in myocardial oxygen consumption (MVo2) during sevoflurane, whereas it did not change in spite of the decrease in MVO2 during isoflurane. The CX vascular resistance decreased significantly during isoflurane but not during sevoflurane. Moreover, the myocardial oxygen extraction ratio (Mo2exr) decreased at 0.75 and 1.5 MAC isoflurane and at 1.5 MAC sevoflurane, and the decrease in Mo2exr was significantly greater during isoflurane than during sevoflurane. The results suggest that sevoflurane is a less potent coronary arteriolar dilator than isoflurane, and that neither sevoflurane or isoflurane has a direct effect on the diameter of large coronary arteries.

Carbachol, norepinephrine, and hypocapnia stimulate phosphatidylinositol turnover in rat tracheal slices

BACKGROUND

The intracellular mechanisms involved in the alpha-adrenoceptor- or hyperventilation-induced bronchoconstriction remain unknown. Because there is a direct relationship between phosphatidylinositol (PI) metabolism and airway smooth muscle contraction induced by muscarinic agonists, the authors examined the effects of carbachol (CCh), norepinephrine (NE), and hypocapnia on PI turnover in the airway smooth muscle.

METHODS

Rat tracheal slices were incubated in Krebs-Henseleit solution containing LiCl and [3H]myo-inositol in the presence of NE, CCh, or neither. The PCO2 in the solution was 36 +/- 3 mmHg (normocapnia), 19 +/- 2 mmHg (moderate hypocapnia), or 5 +/- 2 mmHg (severe hypocapnia), respectively. [3H]inositol monophosphate (IP1) formed was counted with a liquid scintillation counter.

RESULTS

Basal IP1 formed was greater at severe hypocapnia than at normocapnia. Norepinephrine- and CCh-induced IP1 formation were also greater at hypocapnia than at normocapnia.

CONCLUSIONS

These results indicate that CCh, NE, and hypocapnia stimulate PI turnover in the airway smooth muscle, which would cause bronchoconstriction, and hypocapnia also augments NE- and CCh-induced PI turnover, which could cause worsening of exercise-induced asthma and vagotonic asthma, respectively.

Effects of intravenous anesthetics on phosphatidylinositol turnover in rat cerebral cortical prisms

Noradrenergic pathways in the brain have been thought to be related to the site of anesthetic action. Norepinephrine (NE) in the central nervous system stimulates phosphatidylinositol (PI) turnover through alpha 1-adrenergic receptors. The present study was designed to examine the effects of intravenous anesthetics on NE-induced PI turnover in rat cerebral cortical prisms. NE-induced inositol monophosphate (IP1) formation was inhibited by droperidol (dose for 50% inhibition [ID50], 0.0258 +/- 0.00023 microM [mean +/- SE]), fentanyl (2.36 +/- 0.0017), diazepam (201 +/- 2.12), and thiamylal (231 +/- 1.94) in a dose-dependent manner, but was not affected by ketamine. Naloxone or flumazenil did not attenuate the inhibitory effect of fentanyl or diazepam on NE-induced IP1 formation. The results suggest that these effects on the PI turnover in the cortex may be related to their pharmacologic properties including the anesthetic action.

Quantitative evaluation of gastric contents using ultrasound

STUDY OBJECTIVES

To describe a method of the authors' design for estimating gastric volume quantitatively using ultrasound and to evaluate the usefulness of this method in the clinical setting.

DESIGN

Prospective, two-phase clinical study.

SETTING

University hospital. PATIENTS AND VOLUNTEERS: Phase 1 study: 31 patients who were undergoing general anesthesia and had no gastrointestinal disorder. Phase 2 study: 8 healthy volunteers.

INTERVENTIONS

With each subject in the sitting position, a cross-sectional view of the stomach was obtained via ultrasound along the median line of the epigastric region. The cross-sectional area of the stomach (CSA) was measured by the analysis unit on the basis of the trace-enclosure method, and a mean value was obtained from triplicate measurements.

MEASUREMENTS AND MAIN RESULTS

In the phase 1 study, CSA was measured after the patient had fasted for 1 hour, 4 hours, and more than 8 hours. CSA (cm2) was 19.2 +/- 0.9 cm2 at 1 hour, 11.0 +/- 0.7 cm2 at 4 hours, and 5.5 +/- 0.4 cm2 at more than 8 hours. That is, CSA significantly decreased as fasting time was prolonged (p < 0.001 for 1 hour vs. more than 8 hours and 4 hours vs. more than 8 hours). Most of the patients (87%) who fasted for more than 8 hours had a CSA less than 8.0 cm2. In the phase 2 study, after patients had fasted for more than 8 hours, CSA was measured both before and 5 minutes after the patient drank 50 ml of milk. CSA was 5.0 +/- 0.5 cm2 before and 8.5 +/- 0.9 cm2 after ingestion of the milk (p < 0.001). All subjects had a CSA less than 8.0 cm2 before drinking the milk, whereas only 2 of 8 patients had a CSA less than 8.0 cm2 after.

CONCLUSIONS

This method would be useful to estimate gastric contents quantitatively, and a CSA of 8.0 cm2 might be a valid indicator of an empty stomach.

Combined effects of adrenergic and intravenous anesthetic agents on inositol monophosphate levels in rat liver prisms

Combined effects of adrenergic and intravenous anesthetic agents on phosphatidylinositol (PI) turnover were studied using rat liver prisms incubated with [3H]myo-inositol. Rat liver prisms responded to epinephrine, norepinephrine and phenylephrine dose-dependently with an increase in inositol monophosphate (IP1) formation but they did not respond to ephedrine. Dopamine-induced effects were seen only at concentrations as high as 10(-4) mol.l-1. The enhancement of IP1 formation induced by epinephrine was potentiated by thiamylal at concentrations of 10(-5) mol.l-1 and 10(-4) mol.l-1, remained unaffected by ketamine, fentanyl or midazolam, but was dose-dependently inhibited by droperidol. The present results from in vitro studies of liver cell metabolism suggest that alpha-adrenergic agents in combination with barbiturates may potentiate liver cell damage by activation of PI turnover and interrelated intracellular Ca++ accumulation.

[Caesarean section in a patient with past history of fulminant malignant hyperthermia]

Caesarean section in a 26 year old patient (50 kg, normal weight 36 kg) with past history of fulminant malignant hyperthermia (f-MH) is reported. Hyperthermia over 42 degrees C and subsequent cardiac arrest occurred during general anesthesia with nitrous oxide-oxygen-halothane and succinylcholine when she had been planned to perform hip joint arthroplasty at the age of 7. Prophylactic oral dantrolene administration started 4 days before the operation and the dose went up to 75 mg. Further 25 mg was given as premedication on the day of the operation. Intravenous dantrolene was administered 1.2 mg.kg-1 during the operation and 0.6 mg.kg-1 on the day after surgery. The Caesarean section was performed under spinal anesthesia with hyperbaric tetracaine 20 mg. No clinical symptoms of MH occurred during perioperative period. The delivered baby was a healthy female and no side effects of dantrolene were observed.

[Free and conjugated catecholamines in gastric and bile juice during surgical operations]

From 40 patients under surgical operation, gastric or bile juice was obtained to determine the possible excretion of free and conjugated catecholamine (CA) into the two kinds of juice. The patients were divided into normal renal function group and chronic renal failure group and former group was further divided into the dopamine (DA)-administered group and the non-DA-administered group. In the non-DA group with normal renal function, the gastric juice contained 0.30 +/- 0.11ng.ml-1 of free and 0.12 +/- 0.06ng.ml-1 of conjugated norepinephrine (NE) and also 0.09 +/- 0.07ng.ml-1 of free and 0.40 +/- 0.10ng.ml-1 of conjugated DA. In DA group, the gastric juice contained 2.01 +/- 0.41ng.ml-1 of free and 3.66 +/- 0.84ng.ml-1 of conjugated DA respectively. Significant differences in DA were observed between two groups. In the bile juice, the conjugated NE increased significantly from 0.15 +/- 0.05 ng.ml-1 to 1.24 +/- 0.34ng.ml-1 and also the conjugated DA increased significantly from 2.17 +/- 0.77ng.ml-1 to 21.33 +/- 5.23ng.ml-1 by infusion of DA at the rate of 2 micrograms.kg-1.min-1 for 197 +/- 48min. In chronic renal failure group, the conjugated NE and DA increased significantly to 1.04 +/- 0.27ng.ml-1 and 1.64 +/- 0.61ng.ml-1 respectively compared to that of normal renal group. It was confirmed that gastric juice and bile juice contain the free and conjugated CA during surgical operation and by the infusion of DA, free and conjugated DA are excreted into gastric juice and bile juice and also conjugated CA in the gastric juice from chronic renal failure group is increased.

The effects of prolonged controlled hypotension induced by prostaglandin E1 on renal tubular function

The effects of the prolonged 3-hour and 6-hour controlled hypotension induced by prostaglandin E(1) (PGE(1)) on renal tubular function have been comparatively studied with trimethaphan (TMP; 3-hour hypotensive anesthesia) and enflurane deep anesthesia (6-hour hypotensive anesthesia), using the urine N-acetyl-Beta-D-glucosaminidase (NAG index) and the serum and urine Beta(2)-microglobulin (fractional clearance of Beta(2)-m; Fc-Beta(2)-m) as markers. During 3-hour and 6-hour controlled hypotension PGE(1), NAG index and Fc-Beta(2)-m and urine volume could be maintained without remarkable changes. In the group with TPM, NAG index and Fc-Beta(2)-m significantly increased. The increasing trend was also noted over time in deep anesthesia with enflurane. On 1st postoperative day, Fc-Beta(2)-m significantly increased in PGE(1) group in both 3-hour and 6-hour hypotensive anesthesia, whereas it restored to normal on 2nd postoperative day. Also, in TMP and enflurane deep anesthesia, Fc-Beta(2)-m significantly increased on 1st postoperative day. With the latter, significant increase was also observed on 2nd postoperative day. These results suggest that, in 3-hour and 6-hour controlled hypotension induced by PGE(1), renal tubular function is normally maintained and that it is useful for prolonged controlled hypotensive anesthesia. However, further study is necessary because tubular dysfunction might appear on 1st postoperative day.

Comparison of the effects of amrinone and dobutamine on hemodynamics and myocardial oxygen balance in dogs with experimental left ventricular failure

The purpose of the present study was to induce left ventricular failure in anesthetized dogs by repeated ventricular fibrillation and then to determine if amrinone is effective in circulatory support by comparing the effects of amrinone and dobutamine. After the repetitive ventricular fibrillation, mean arterial pressure and stroke volume index decreased, pulmonary capillary wedge pressure (PCWP) increased, and acute left ventricular failure occurred. Thereafter, dogs were divided into the following four groups. In Group C (n = 6), normal saline was administered; in Group D (n = 6), dobutamine was administered at 7 micrograms/kg/min; and in Groups A40 (n = 6) and A80 (n = 7), amrinone was administered at 40 micrograms/kg/min and 80 micrograms/kg/min, respectively. Stroke volume index increased by 78% in Group D and 46% in both Groups A40 and A80. Pulmonary capillary wedge pressure decreased by 44% in Group A40 and 38% in Group A80, but remained unchanged in Group D. Similarly, total peripheral resistance decreased by 32% in Group A40, 29% in Group A80, but remained unchanged in Group D. These results suggest that amrinone increased cardiac output and decreased both preload and afterload. In the coronary circulation, both drugs caused direct coronary vasodilation since they increased myocardial oxygen supply in excess of the increase in myocardial oxygen demand. Neither drug produced signs of myocardial ischemia, as indicated by myocardial lactate metabolism. Amrinone should be a useful drug after open heart surgery, especially in cases where significant adverse effects of catecholamines occur or where a low-output state with increased preload and afterload exists.

[The effects of dopamine and amrinone on myocardial oxygen demand-supply relationship in dogs with coronary artery stenosis]

This study examined the effects of dopamine (DA) and amrinone (AM) on myocardial oxygen demand-supply relationship in coronary artery stenotic areas (40-60% reduction of coronary blood flow by a constrictor) by measuring myocardial oxygen tension (PmO2) after administration of either DA or AM in twelve dogs. The results were as follow; 1) PmO2 showed no significant changes with either DA or AM, but it showed a significant inverse correlation with HR with DA or AM. Thus changes in HR affected the myocardial oxygen balance. 2) AM showed strong coronary vasodilating action in non-stenotic areas and possibly led to 'steal'. 3) Looking at indicators of myocardial ischemia, MAP/HR was significantly correlated with PmO2, and it reflected the myocardial oxygen demand-supply relationship better than RPP or DPTI/TTI. When DA or AM is used in patients with coronary artery disease, both drugs seem to maintain myocardial oxygen balance unless they cause tachycardia. Caution is required in the administration of AM because of the possibility of 'steal'.

Ultrastructure of the concentric membrane system in asci of Arthroderma vanbreuseghemii

An ultrastructural study was performed on the ascosporogenesis in Arthroderma vanbreuseghemii. Young gymnothecia of the fungus were treated with four different schedules: (1) glutaraldehyde and osmium tetroxide fixation, (2) potassium permanganate fixation, (3) tannic acid, with or without glutaraldehyde, and osmium tetroxide fixation, (4) periodic acid-alkaline bismuth (PABi) staining after glutaraldehyde and osmium tetroxide fixation. The glutaraldehyde- and osmium tetroxide-fixed asci had a concentric membrane system (CMS), concomitantly with the double membrane system (DMS) that eventually delimited ascospores. The CMS consisted of multiple membranes of a myelinoid appearance, and continued to the ascus plasma membrane and also to the DMS. In contrast, potassium permanganate fixation and tannic acid and osmium tetroxide fixation without glutaraldehyde failed to reveal such a structure as the CMS within the asci. PABi-positive materials were found on the marginal glycogen granules, the CMS, the DMS, and the ascus plasma membrane. These observations suggest that the CMS is lipid-poor and not composed of true membranes. It is not the direct source of the DMS, but merely participates in the production of cell wall materials during ascosporogenesis with the marginal glycogen granules as a substrate.

Cutaneous calcinosis in a neonate following extravasation of calcium gluconate

Cutaneous calcinosis following extravasation of calcium gluconate in a 6-day-old neonate is reported. After extravasation of a 10% calcium gluconate infusion, rapid and marked swelling, erythema, and signs of soft tissue necrosis developed over the dorsum of the right hand and wrist. Small eschars were soon formed on the skin surface and began to slough, the underlying base appearing necrotic. Through the small channels of the destroyed epidermis, tiny white pieces of calcific masses were eliminated spontaneously. Histologically, the dermal collagen was massively degenerated and the calcium deposits were found as amorphous masses throughout the dermis and subcutaneous adipose tissue, surrounded by mild lymphohistiocytic cell infiltration. This is a case which again warns of the danger of using 10% calcium gluconate intravenously in the neonate or young infant.

Trichophyton mentagrophytes skin infections in laboratory animals as a cause of zoonosis

Recent sporadic distribution in Japan of Trichophyton mentagrophytes skin infections among laboratory rats or guinea pigs is reported. Six cases of laboratory infection by the fungus in humans who came in direct contact with the affected animals are also presented. Mating experiments with the causative fungi isolated from the animal and human skin lesions revealed that all but one sexually reactive strains belonged to the "+" mating type of Arthroderma vanbreuseghemii. A retrospective epidemiologic study ascertained that most of the affected rats were those derived from the same breeding colony of a certain experimental animal producing-co-operation in Saitama prefecture, where it had been produced by conventional methods of specific pathogen-free parental colony maintained in a barrier system. These two pieces of evidence suggest a possible transmission of the etiologic agent from some healthy carrier or infected hair-droppings in the environment to the breeding colony, during its breeding, or maintenance by the producer.

Glucose tolerance in pustulosis palmaris et plantaris

Glucose tolerance was investigated in 41 patients with pustulosis palmaris et plantaris. Twenty-eight (68%) of the patients showed abnormal results. These findings suggest that pustulosis palmaris et plantaris is associated with impaired carbohydrate metabolism.