Alpha-2 adrenoceptor activity affects propofol-induced sleep time

alpha(2) Adrenoceptor activity is involved in the mechanism of anesthesia. Clonidine, a alpha(2) adrenoceptor agonist, and yohimbine, a alpha(2) adrenoceptor antagonist, increase and decrease barbiturate-induced sleep times. In this study, we examined the effects of these drugs on propofol-induced sleep time. One-hundred-eighteen male Wistar rats weighing 320-400 g were used. Rats received saline, yohimbine (1, 0.1, or 0 mg/kg), or clonidine (300, 30, 3, or 0 microg/kg) intraperitoneally followed by 60 mg/kg of propofol in various combinations. In two series of experiments, either sleep time or prefrontal cortex norepinephrine release (microdialysis) was measured. One milligram/kilogram of yohimbine decreased propofol-induced sleep time to approximately 70% of control, and this was accompanied by an increase in perfusate norepinephrine of approximately 240% of control. Clonidine increased sleep time approximately 260% (300 microg/kg) and approximately 170% (30 microg/kg), and this was accompanied by a decrease (approximately 60% in both doses) in perfusate norepinephrine. In the present study, we show that the alpha(2) antagonist, yohimbine, decreased and the alpha(2) agonist, clonidine, increased propofol-induced sleep times. These changes were essentially mirrored in both groups by changes in norepinephrine release in the prefrontal cortex.

IMPLICATIONS

Central alpha(2) adrenoceptor is thought to be involved in several IV anesthetics-induced sleep. In this study, activation of the receptor increased the propofol-induced sleep time, whereas its inhibition decreased the sleep time. The results provide further evidence that the alpha(2) receptor is a good tool to elucidate the mechanism of anesthetics-induced sleep.

Does indocyanine green accurately measure plasma volume early after cardiac surgery?

Potential overestimation of plasma volume (PV) determination by the conventional indocyanine green (ICG) dilution method (PV-ICG) can occur when generalized capillary protein leakage is present, because ICG binds to proteins. We recently reported that this overestimation can be recognized by simultaneous measurement of the initial distribution volume of glucose (IDVG). We examined whether overestimation of PV-ICG and further ICG-pulse dye densitometry-derived plasma volume (PV-PDD) can occur early after cardiac surgery by using the PV-ICG/IDVG ratio as an indicator. Possible overestimation was defined as a ratio higher than 0.45. Twenty-four consecutive postcardiac surgical patients were enrolled. PV-ICG, PV-PDD, and IDVG were calculated simultaneously after admission to the intensive care unit and on the first postoperative day. The mean +/- SD PV-ICG/IDVG ratio for 47 recordings was 0.38 +/- 0.05. Four had a PV-ICG/IDVG ratio higher than 0.45, and the highest was 0.48. The mean PV-PDD/IDVG ratio for a total of 47 recordings was 0.39 +/- 0.10. There were extremely high or low ratios observed in PV-PDD determinations, but they were not observed in PV-ICG determinations. Results suggest that most of the PV-ICG measurements are accurate, but inaccuracy of PV-PDD can occur early after cardiac surgery.

IMPLICATIONS

Overestimation of indocyanine green-derived plasma volume can occur in the presence of generalized capillary protein leakage. This overestimation was examined early after cardiac surgery by using the simultaneous measurement of the initial distribution volume of glucose. We suggest that overestimation of the traditional dye dilution method is negligible, but apparent over- or underestimation of pulse dye densitometry-derived plasma volume cannot be negligible.

Spasmolytic effects of colforsin daropate on serotonin-induced pulmonary hypertension and bronchoconstriction in dogs

BACKGROUND

We have previously found that agents increasing intracellular cAMP levels of smooth muscles, such as PDE3 inhibitors, aminophylline and prostaglandin E1, produce both bronchodilation and pulmonary vasodilation in serotonin-induced pulmonary hypertension and bronchoconstriction models. In the present study we have simultaneously evaluated the spasmolytic effects of colforsin daropate, a novel forskolin derivative, on serotonin-induced pulmonary hypertension and bronchoconstriction.

METHODS

Ten mongrel dogs were anesthetized with pentobarbital. The pulmonary hypertension and bronchoconstriction were elicited with serotonin (10 microg/kg + 1 mg x kg(-1) x h(-1)) and assessed as percentage changes in pulmonary vascular resistance (PVR) and bronchial cross-sectional area (BCA) (basal = 100%). Initially, the relaxant effects of colforsin daropate (0-300 microg/kg) were determined. The PVR and BCA were assessed before and 30 min after serotonin infusion began and 5 min after each dose of colforsin daropate. To determine whether colforsin daropate-induced relaxation is independent of plasma catecholamine, propranolol 0.4 mg/kg was given following colforsin daropate 300 microg/kg i.v.

RESULTS

Colforsin daropate reversed both pulmonary hypertension and bronchoconstriction dose-dependently: -logED50 (95% confidence intervals, mean ED50) for pulmonary hypertension and bronchoconstriction 5.44 (5.08-5.80, 3.6 microg/kg) and 4.90 (4.06-5.20, 12.5 microg/kg), respectively. However, colforsin daropate (>or= 30 microg/kg) produced a more pronounced systemic than pulmonary vasodilation. Although colforsin daropate (>or= 30 microg/kg) significantly increased plasma catecholamines, propranolol did not reverse the relaxant effects.

CONCLUSIONS

Colforsin daropate may attenuate bronchoconstriction and pulmonary hypertension. In addition, as beta-blockade did not change the attenuation, the relaxant effects may be independent of plasma catecholamines.

Ketamine and the inhibition of albumin extravasation in chemical peritonitis in rat

BACKGROUND AND OBJECTIVE

It was previously reported that topical ketamine inhibits albumin extravasation in a rat chemical peritonitis model. Using the same model, the present study investigated whether intravenous ketamine inhibited this extravasation.

METHODS

Twenty-four rats anaesthetized with pentobarbital (75 mg kg(-1)) were randomly assigned to two groups: ketamine and a 0.9% NaCl (saline) group (n = 12 each). Ketamine 1% or saline 0.1 mL kg(-1) min(-1) was given intravenously for 60 min to the respective group. After the abdomen had been opened, peritonitis was elicited by topically applying a filter paper containing 0.02 M HCl 0.07 mL onto the surface of the appendix or caecum for 5 min. Fifteen minutes after removal of the filter paper, Evans' blue dye (50 mg kg(-1)) was injected intravenously. The extravasated dye was colorimetrically quantified by a spectrophotometer at 620 nm.

RESULTS

The infusion of ketamine significantly reduced Evans' blue extravasation: 5.26 (range 4.18-6.34) microg per 100 mg tissue compared with the saline group control: 6.81 (5.93-7.69) microg per 100 mg tissue (P < 0.05).

CONCLUSIONS

It is suggested that ketamine anaesthesia may reduce albumin extravasation in inflammatory tissues.

[A study on Seishu Hanaoka's "Nyugan Seimei Roku": a name list of breast cancer patients]

Treatment of breast cancer was the life work of Seishu Hanaoka (1760-1836) and one of his greatest achievements was the development of an oral general anesthetic called "Mafutsu-san." His intense concern about the disease drove him to develop the anesthetic. This is substantiated by the facts that the first administration of the anesthetic was a patient named Kan Aiya for a tumor excision of her left breast in October 13th, 1804, and the 154 patients with breast cancer were listed in the "Nyugan Seimei Roku" or "A Name List of Breast Cancer Patients." Thus the study of his breast cancer patients is essential and indispensable for understanding Seishu Hanaoka's medical biography in depth. However, the descriptions of names, dates and addresses of the patients written in "Nyugan Seimei Roku" are incorrect and they do not always agree with those in other historical documents. We also do not know whether the dates mean those of the first examination or those of surgical operations. Several case records of breast cancer patients described by his disciples have become available, and by comparing them with "Nyugan Seimei Roku," we could know more detailed and correct conditions of the patients. The case of the wife of Teiseki Matsubara is a typical one, in which the exact date and the cause of her death were eluciated.

[A case of ventricular fibrillation during emergency clipping operation for cerebral aneurysm]

A 59 year-old woman with subarachnoid hemorrhage underwent emergency neck clipping of cerebral aneurysm. Her preoperative examination showed atrial fibrillation, pulmonary edema and hypokalemia. Ventricular fibrillation developed immediately after clipping of the aneurysm and recurred 7 times thereafter during the surgery. Hypokalemia was corrected, and hypoxemia and other factors leading to ventricular fibrillation were excluded. RR interval was prolonged prior to ventricular fibrillation. Therefore intravenous temporary cardiac pacemaker was inserted immediately after the end of the surgery. It prevented successfully the prolongation of RR interval as well as ventricular fibrillation. The present case suggests that we should pay attention to the possibility of ventricular fibrillation during emergency radical surgery for ruptured cerebral aneurysm, and that cardiac pacemaker is useful to prevent ventricular fibrillation following prolongation of RR interval.

Unventilated airway is time-dependently constricted in paralyzed dogs

BACKGROUND

Apnea has been reported to produce bronchoconstriction and to cause hypoxia, hypercapnia, and modulation of vagal afferent nerves, which also change airway tone. In this study, the authors determined the mechanism of apnea-induced bronchoconstriction.

METHODS

Twenty-eight dogs anesthetized and paralyzed were assigned to four groups (n = 7 each): apnea after artificial ventilation with 50% and 100% O2 groups (apnea-50% O2 and apnea-100% O2 groups, respectively), an apnea plus vagotomy group (fraction of inspired oxygen [FiO2] = 1.0), and a one-lung ventilation group (FiO2 = 1.0). The trachea was intubated with a single- or double-lumen tube in the three apnea groups or the one-lung ventilation group, respectively. The bronchial cross-sectional area (BCA) was assessed by the authors' bronchoscopic method. In the apnea-100% O2 and apnea plus vagotomy groups, a respirator was turned off for 5 min to produce apnea. In the apnea-50% O2 group, apnea was produced for 3 min. In the one-lung ventilation group, the right lumen was blocked for 5 min, and 15 min later, the left lumen was blocked for 5 min. BCA, arterial oxygen tension (PaO2), and arterial carbon dioxide tension (PaCO2) were assessed every minute.

RESULTS

The BCA in intact dogs time-dependently decreased by approximately 20% and 40% at 3 and 5 min after apnea started, respectively, whereas they did not in vagotomized dogs. In the apnea-50% O2 and apnea-100% O2 groups, bronchoconstriction could occur without hypoxemia, although hypercapnia was observed in all dogs. In the one-lung ventilation group, despite the fact that PaCO2 increased by only 2 mmHg without hypoxemia, unventilated BCA time-dependently decreased by 33.6 +/- 10.3%, whereas ventilated BCA did not.

CONCLUSION

The current study suggests that the unventilated airway may constrict spontaneously. In addition, the airway constriction could be vagally mediated but not due to hypoxia and hypercapnia.

Effect of 6-hydroxydopamine on host resistance against Listeria monocytogenes infection

Recent studies have shown that immunocompetent cells bear receptors of neuropeptides and neurotransmitters and that these ligands play roles in the immune response. In this study, the role of the sympathetic nervous system in host resistance against Listeria monocytogenes infection was investigated in mice pretreated with 6-hydroxydopamine (6-OHDA), which destroys sympathetic nerve termini. The norepinephrine contents of the plasma and spleens were significantly lower in 6-OHDA-treated mice than in vehicle-treated mice. The 50% lethal dose of L. monocytogenes was about 20 times higher for 6-OHDA-treated mice than for vehicle-treated mice. Chemical sympathectomy by 6-OHDA upregulated interleukin-12 (IL-12) and tumor necrosis factor-alpha (TNF-alpha) production in enriched dendritic cell cultures and gamma interferon (IFN-gamma) and TNF-alpha production in spleen cell cultures, whereas chemical sympathectomy had no apparent effect on phagocytic activities, listericidal activities, and nitric oxide production in peritoneal exudate cells and splenic macrophages. Augmentation of host resistance against L. monocytogenes infection by 6-OHDA was abrogated in IFN-gamma(-/-) or TNF-alpha(-/-) mice, suggesting that upregulation of IFN-gamma, IL-12, and TNF-alpha production may be involved in 6-OHDA-mediated augmentation of antilisterial resistance. Furthermore, adoptive transfer of spleen cells immune to L. monocytogenes from 6-OHDA-treated mice resulted in untreated naive recipients that had a high level of resistance against L. monocytogenes infection. These results suggest that the sympathetic nervous system may modulate host resistance against L. monocytogenes infection through regulation of production of IFN-gamma, IL-12, and TNF-alpha, which are critical in antilisterial resistance.

Orexin A and B evoke noradrenaline release from rat cerebrocortical slices

1. Orexin A and B, recently identified in the rat hypothalamus are endogenous neuropeptide agonists for the G-protein coupled orexin-1 (OX1) and orexin-2 (OX2) receptors. 2. In the present study, we have examined the effects of orexin A, B and raised extracellular K(+) on noradrenaline release from the rat cerebrocortical slice. We have compared this with other sleep-wake-related (excitatory) neurotransmitters; dopamine, glutamate, serotonin and histamine. 3. Neurotransmitter release studies were performed in rat cerebrocortical slices incubated in modified Krebs buffer (with and without Ca(2+)+EGTA 1 mM) with various concentrations of orexin A, B and K(+) for various times. 4. Orexin A and B-evoked (10(-7) M) noradrenaline release was time-dependent reaching a maximum some 10 min after stimulation. K(+) (40 mM) evoked release was also time dependent but reached a maximum after 6 min. Orexin A, B and K(+) stimulation of release was concentration dependent with pEC(50) and E(max) (% of basal) values of 8.74+/-0.32 (1.8 nM) and 263+/-14% and 8.61+/-0.38 (2.4 nM) and 173+/-7% and 1.43+/-0.02 (37 mM) and 1430+/-70%, respectively. Orexin-evoked release was partially extracellular Ca(2+) dependent. 5. Of the other transmitters studied there was a weak orexin A and B stimulation of glutamate release. In contrast K(+) evoked dopamine, glutamate, histamine and serotonin release with pEC(50) and E(max) (% of basal) values of 1.47+/-0.05 (34 mM) and 3430+/-410%, 1.38+/-0.04 (42 mM) and 1240+/-50%, 1.47+/-0.02 (34 mM) and 480+/-10% and 1.40+/-0.05 (40 mM) and 560+/-60% respectively. 6. We conclude that the neuropeptides orexin A and B evoke noradrenaline release from rat cerebrocortical slices.

Daily changes of the area of density in the dependent lung region - evaluation using transesophageal echocardiography

OBJECTIVE

To evaluate the daily changes of the area of density using transesophageal echocardiography (TEE) in acute respiratory distress syndrome (ARDS) and acute lung injury (ALI) patients.

DESIGN

Retrospective observational study.

SETTING

General ICU in a university hospital.

PATIENTS

Fifteen patients with ARDS or ALI who underwent TEE examination for more than 5 days.

MEASUREMENTS

Densities in the lower left lung region were observed through the descending aorta by TEE. Daily changes of the area of density were evaluated. The areas of density estimated by TEE were compared with those obtained by computed tomography (CT). The relation between the area of density and PaO(2)/FIO(2)was calculated.

RESULTS

The area of density in the dependent lung region measured by TEE was 11.1+/-5.7 cm(2) (mean +/- SD) at the mid-esophageal position. The area of density in ARDS patients changed daily from 12.0+/-2.8 cm(2) to 8.5+/-6.7 cm(2). The areas of density evaluated using TEE in the left lung correlated significantly with those estimated using CT ( r=0.72, p<0.01). In addition, we found a significant correlation between PaO(2)/FIO(2) and the area of density estimated by TEE ( r=-0.53, p<0.05).

CONCLUSION

Using TEE, we could evaluate daily changes of the area of density in the dependent lung region in the intensive care situation. The areas of density in ARDS patients changed from day to day following the changes of oxygenation.

[A case of long-term respiratory management following resection of a huge facial hemangioma]

A 49 year-old-woman was scheduled for resection of a huge hemangioma of the face and neck region. After the resection, severe edema developed on the tongue, larynx, and pharynx even leaving no space between the tracheal tube and these tissues. Prolonged respiratory management with endotracheal tube intubation was needed to maintain the upper airway for more than three weeks. Tracheostomy was performed 27 days after the operation. Two weeks later, the edema of the upper airway subsided. Thereafter her clinical course was uneventful, and she was discharged 22 days after the tracheostomy. Resection of a huge facial and neck hemangioma should be carefully managed as it can be followed by unexpected severe postoperative upper airway edema leading to suffocation.

Insertion of intradermal needles into painful points provides analgesia for intractable abdominal scar pain

BACKGROUND AND OBJECTIVES

Conventional treatments are often ineffective for patients having painful abdominal scars. There are painful points in and around scar tissue. We tested the hypothesis that insertion of intradermal needles into these painful points reduces scar pain.

METHODS

Patients with abdominal scar pain with painful points that is not relieved by conventional treatments were allocated to a treatment group (n = 23), a sham-treatment group (n = 23), or a control group (n = 24). In the treatment group, intradermal needles were inserted into painful points detected by a pressure threshold meter (pain < or = 2.5 kg/cm(2)). In the sham-treatment group, the same needles were inserted into nonpainful points. The needles were kept in place for 24 hours. This process was repeated 20 times over a 4-week period. Responses were evaluated before and at the end of treatment, and 4 and 26 weeks after the treatment. Continuous and lancinating pain was evaluated on a 10-cm visual analog scale. We measured the area of pain and the pressure required to initiate painful-point pain. All patients took diclofenac as needed and completed a diary of daily diclofenac consumption.

RESULTS

Patients in the treatment group showed a marked reduction in all pain parameters (>70%). In contrast, analgesia was minimal in the other groups. The decreases in the pain threshold pressure correlated with the decreases in continuous and lancinating pain (r =.57 and r =.63, respectively).

CONCLUSION

Our data suggest that insertion of intradermal needles into painful points is a remarkably effective treatment for intractable abdominal scar pain. Analgesia presumably results from inactivation of painful points, through a yet to be elucidated mechanism.

Intraoperative prostaglandin E1 improves antimicrobial and inflammatory responses in alveolar immune cells

OBJECTIVE

Anesthesia and surgery decrease antimicrobial and increase proinflammatory functions of alveolar immune cells. Thus, anti-inflammatory agents that do not further suppress antimicrobial functions are required. We tested the hypothesis that intraoperative prostaglandin E1 (PGE1) suppresses proinflammatory responses and prevents the reduction in antimicrobial responses of alveolar immune cells.

DESIGN

Prospective, randomized, controlled, double-blind study.

SETTING

University hospital.

PATIENTS

A total of 40 patients undergoing elective orthopedic surgery under propofol/fentanyl anesthesia.

INTERVENTION

In double-blind fashion, the patients received PGE1 from the beginning to the end of surgery (PGE1 group, n = 20) or nothing (control group, n = 20).

METHODS AND MAIN RESULTS

Alveolar immune cells were harvested by bronchoalveolar lavage immediately after induction of anesthesia; 2, 4, and 6 hrs after induction of anesthesia; and at the end of surgery. We measured opsonized and nonopsonized phagocytosis. Microbicidal activity was evaluated to directly kill Listeria monocytogenes in alveolar macrophages. Finally, we determined the expression of proinflammatory cytokines including interleukin (IL)-1beta, IL-8, interferon-gamma, and tumor necrosis factor-alpha, and that of anti-inflammatory cytokines (IL-4 and IL-10) by semiquantitative polymerase chain reaction. Nonopsonized and opsonized phagocytosis and microbicidal activity of alveolar macrophages decreased and the expression of genes for all pro- and anti-inflammatory cytokines increased significantly over time in both groups. Starting 2-4 hrs after induction of anesthesia, the increases in gene expression of proinflammatory cytokines were 1.5-3 times smaller in the PGE1 than in the control group. Starting 6 hrs after anesthesia, the increase in gene expression of IL-10 was 1.5-3 times greater in the PGE1 than in the control group. Intraoperative decreases in phagocytic and microbial activities were the same in the two groups.

CONCLUSION

Intraoperative PGE1 not only suppressed proinflammatory responses, but also protected antimicrobial functions of alveolar macrophages, possibly because PGE1 is mostly inactivated in the pulmonary intravascular space. Our results suggest that intraoperative PGE1 protects the pulmonary immune defense in alveolar immune cells.

Plasma proinflammatory cytokine response to surgical stress in elderly patients

We investigated the change of plasma cytokines concentrations in elderly patients during lower abdominal surgery. Plasma interleukin (IL-)6 concentrations (68.0+/-15.4 and 36.1+/-20.7 pg/ml) in elderly patients at 24 h and at 3 days after surgery were significantly higher than those (35.1+/-21.5 and 18.6+/-10.6 pg/ml) of young adults. Plasma IL-6 concentrations (92.3+/- 31.9 pg/ml) in elderly patients anesthetized with propofol and fentanyl were significantly higher at the end of the operation than that (57.9+/-36.7 pg/ml) of elderly patients anesthetized with sevoflurane and fentanyl. In conclusion, elderly patients have an increased and delayed IL-6 response to surgical trauma compared with young adults. Plasma IL-6 production after surgical trauma in elderly patients with total intravenous anesthesia with propofol was significantly higher than that in elderly patients with sevoflurane anesthesia.

The relationship between pneumatic tourniquet time and the amount of pulmonary emboli in patients undergoing knee arthroscopic surgeries

Near-fatal pulmonary embolism can occur immediately after tourniquet release after orthopedic surgeries. In this study, we determined the relationship between tourniquet time and the occurrence of pulmonary emboli in 30 patients undergoing arthroscopic knee surgeries, by using transesophageal echocardiography. The right atrium (RA) was continuously monitored by transesophageal echocardiography, and the number of emboli present was assessed with the following formula: Amount of emboli = 100 x [(total embolic area in the RA after tourniquet release) - (total area of emboli or artifact in the RA before tourniquet release)]/(RA area). The area was assessed 0-300 s after tourniquet release by using image-analysis software. The peak amount of emboli appeared approximately 50 s after tourniquet release. In addition, there was a significant correlation between amount of emboli (Ae [%]) and tourniquet time (Ttq [min]): (Ae = 0.1 x Ttq - 1.0, r = 0.795, P < 0.01). This study suggests that acute pulmonary embolism may occur within 1 min of tourniquet release and that the number of emboli is dependent on Ttq.

Rebound perioperative hyperkalemia in six patients after cessation of ritodrine for premature labor

IMPLICATIONS

This report describes six patients who had marked hyperkalemia 60-150 min after cessation of intravenous ritodrine, which had been administered for management of preterm labor. Abnormal electrocardiographic findings are very important clues for a prompt diagnosis of hyperkalemia.

Comparison of initial distribution volume of glucose and plasma volume in thoracic fluid-accumulated patients

OBJECTIVE

We have reported that initial distribution volume of glucose indicates the central extracellular fluid volume in the presence of fluid gain or loss. The purpose of this study was to describe changes in initial distribution volume of glucose, plasma volume determined by the indocyanine green dilution method (PV-ICG), and thoracic fluid content by thoracic electrical bioimpedance in patients with or without apparent thoracic fluid accumulation in the absence of pleural effusion. We also sought to test whether initial distribution volume of glucose rather than PV-ICG mirrors thoracic fluid content.

DESIGN

Prospective, clinical study.

SETTING

General intensive care unit.

PATIENTS

Eleven consecutive patients with apparent thoracic fluid accumulation as judged by thoracic fluid content >0.05/ohm and underlying pathology and 20 consecutive acute myocardial infarction patients within 24 hrs after its onset were selected for study. None of the acute myocardial infarction patients had thoracic fluid content >0.05/ohm.

INTERVENTIONS

Five grams of glucose and 25 mg of indocyanine green were administered simultaneously to calculate initial distribution volume of glucose and PV-ICG daily for the fluid-accumulated patients, and the same dosages were administered to the acute myocardial infarction patients immediately after their admission to the intensive care unit after percutaneous coronary angioplasty. Only the data on the day of the maximal and minimal thoracic fluid content in the fluid-accumulated patients were used for the study. The relationship between these two fluid volumes and thoracic fluid content was evaluated in the two patient groups.

MEASUREMENTS AND MAIN RESULTS

Initial distribution volume of glucose and thoracic fluid content rather than PV-ICG and thoracic fluid content moved together in the same direction in each fluid-accumulated patient. Neither pulmonary artery occlusion pressure, central venous pressure, nor PV-ICG produced a better correlation with cardiac index when compared with initial distribution volume of glucose in patients with or without thoracic fluid accumulation.

CONCLUSIONS

We suggest that initial distribution volume of glucose rather than PV-ICG is a better indicator of the intrathoracic blood volume status, even although intravenously administered glucose cannot stay in the intravascular compartment.