Masuhiko Takaori

Sevoflurane anaesthesia for one-lung ventilation with PEEP to the dependent lung in sheep: effects on right ventricular function and oxygenation

This study was undertaken to examine the effect of sevoflurane on right ventricular junction, the safety of sevoflurane for onelung ventilation and the effects of PEEP (positive end-expiratory pressure) to the dependent lung in this model using 12 openchest sheep. Haemodynamic variables, including cardiac output, mean arterial blood pressure, right ventricular pressure and pulmonary arterial pressure, and right ventricular segment shortening (sonomicrometry) were measured. First, animals received 2.0, 3.0 or 4.0% sevoflurane for 20 min each, respectively, during two-lung ventilation to measure the dose-dependent haemodynamic effects of sevoflurane. Then one-lung ventilation was performed with a randomized sequence of 0 (ZEEP), 5 and 10 cm H2O PEEP to the dependent lung under 2.0% sevoflurane anaesthesia after one-hour stabilization. A decrease in systolic segment shortening along with increases in both the end-diastolic and end-systolic lengths of the right ventricle were observed at 3.0 and 4.0% sevoflurane, while global right ventricular function remained substantially unchanged during twolung ventilation. During one-lung ventilation the PaO2 was greater with 5 cm H2O PEEP 198 mmHg (± 25 SEM) than with ZEEP 138 mmHg (± 22) or with 10 cm H2O PEEP 153 mmHg (± 23) (P < 0.05). No differences in haemodynamic variables or segment shortening between ZEEP and PEEPs during one-lung ventilation were observed. We conclude that although sevoflurane causes a dose-dependent depression of right ventricular function, sevoflurane anaesthesia can be safely applied to one-lung ventilation, and that 5 cm H2O PEEP to the dependent lung can improve arterial oxygenation without causing changes in right ventricular function.RésuméCe travail vise à évaluer les effets du sévoflurane sur la fonction ventriculaire droite, sa sécurité en ventilation monopulmonaire et les effets de la pression positive télé-expiratoire (PEEP) sur le poumon inférieur à thorax ouvert chez 12 moutons. On mesure les variables hémodynamiques habituelles: débit cardiaque, pression artérielle moyenne, pression ventriculaire droite, pression artérielle pulmonaire; et par sonomicrométrie, le raccourcissement segmentaire ventriculaire droit. D’abord, les animaux sont anesthésiés au sévoflurane à 2,0, 3,0, or 4,0% pour 20 minutes pendant la ventilation bipulmonaire pour mesurer les effets hémodynamiques du sévoflurane. Ensuite, la ventilation monopulmonaire est initiée avec une séquence randomisée de 0 (ZEEP), 5 et 10 cm H2O PEEP sur le poumon inférieur et maintenue à une concentration de sévoflurane 2% pour une période de stabilisation d’une heure. Une diminution du raccourcissement systolique segmentaire droit et un allongement télédiastolique et télésystolique ventriculaire droit simultanés sont observés sous sévoflurane 3,0 et 4,0%. La fonction ventriculaire droite globale demeure inchangée pendant la ventilation bipulmonaire. Pendant la ventilation monopulmonaire, la PaO2 est plus élevée sous PEEP 5 cm H2O (198 mmHg ± 25 SEM) que sous ZEEP (138 mmHg ± 22) ou sous PEEP 10 cm H2O (153 mmHg ± 23) (P < 0,05). On n’observe pas de différences entre les diverses variables hémodynamiques et au regard du raccourcissement segmentaire entre le ZEEP et le PEEP pendant la ventilation monopulmonaire. Nous concluons que bien que le sévoflurane puisse produire une dépression de la fonction ventriculaire droite proportionnelle à la dose, le sévoflurane peut être utilisé avec sécurité pour la ventilation monopulmonaire et qu’une PEEP de 5 cm H2O appliquée au poumon inférieur peut améliorer l’oxygénation artérielle sans modifier la fonction ventriculaire droite.

Treatment of massive hemorrhage with liposome encapsulated human hemoglobin (NRC) and hydroxyethyl starch (HES) in beagles.

The efficacy of NRC as a substitute for blood transfusion for treatment of acute, massive hemorrhage was evaluated in this study. Fourteen beagles, anesthetized with a mixture of 50% nitrous oxide, 0.97% sevoflurane and oxygen and ventilated by a respirator, were hemodiluted by withdrawal of 12 ml/kg of blood and infusion of isovolemic HES (hemodilution: HD) four times every 10 min. Then the animals were divided into two groups; an HES group, in which the same HDs were continued and an NRC group, in which the HDs were done with NRC. The hematocrit value decreased to 11% in the HES group after eight HDs and to 13% in the NRC group, which had a 3.9% NRCcrit value during the same period. In the NRC group, Cao2 decreased to 7.9 ml/min, which was significantly higher than the 5.9 ml/dl of the HES group. Oxygen consumption decreased to 56 ml/min in the HES group, but in the NRC group, it dropped to 74 ml/min, which was significantly higher than that of the HES group. Cardiac output increased to 1.2 times that of the control after eight HDs and arterial mean pressure decreased to approximately 60%. The above data indicated that NRC delivered sufficient oxygen to tissues, substituting for circulating red cells and maintained aerobic metabolism. Therefore, it should be possible to use NRC successfully for the treatment of cute, massive hemorrhage.

Pleural Effusion After CT-Guided Alcohol Celiac Plexus Block

The accuracy and safety of an alcohol celiac plexus block have been substantially increased by the use of the computerized tomography (CT)-guided technique (1) because most of the complications and failures of a celiac plexus block with conventional radiologic control are closely related to the inappropriate placement of the needles (2,3). We have seen, however, two cases of pleural effusions after celiac plexus blocks with alcohol under CT guidance technique.

The microcirculation during enflurane and isoflurane anaesthesia in dogs

The effects of enflurane and isoflurane of 0.75 and 1.5 MAC on capillary blood flow were studied by the microsphere (9 ± 1 μm in diameter) method in two groups of seven dogs. Simultaneously, changes in the arteriolo-venular shunt were studied by collection of venous blood at a rate of 4.8 ml · min−1 for two minutes. Enflurane anaesthesia at 0.75 MAC decreased capillary blood flow in the thyroid glands (35% of control), left and right ventricular wall (59% and 50%), adrenal gland (59%), liver (63%), spleen (56%), pancreas (35%), omentum (20%), and small intestine (60%) and at 1.5 MAC it decreased further in the thyroid glands (15%), left and right ventricular wall (31% and 32%), adrenal gland (42%), liver (47%), spleen (31%), pancreas (23%), omentum (20%), stomach (45%), and small intestine (54%). No marked changes were noted in the brain, kidney, large intestine or skeletal muscle. The arteriolo-venular shunt was decreased in the kidney from an initial rate of 12.1 to 3.8% at 0.75 MAC and to 2.5% at 1.5 MAC enflurane. In contrast, during isoflurane anaesthesia, capillary blood flow remained unchanged, except for a decrease to the thyroid glands (43%) and right ventricular wall (74%) during 1.5 MAC anaesthesia. However, the arteriolo-venular shunt was increased in the brain from 12.0 to 29.7% and 33.0% during 0.75 and 1.5 MAC isoflurane anaesthesia, respectively. It also increased from 25.0 to 41.0% and 46.3% in the skeletal muscle, and from 8.9 to 19.9% and 17.4% in the whole systemic circulation. These data indicate that capillary blood flow is better preserved during isoflurane than during enflurane anaesthesia, but is associated with increased arteriolo-venular shunting.RésuméLes effets de l’enfurane et de l’isoflurane 0,75 et 1,5 MAC sur le débit capillaire sont étudiés par la méthode des microsphères (9 ±1 μm de diamètre) chez deux groupes de sept chiens. Simultanément, les altérations du shunt artériolo-veinulaire sont étudiées par la collecte de sang veineux à la vitesse de 4,8 ml · min−1 pendant deux minutes. L’anesthésie à l’enflurane 0,75 MAC diminue le débit capillaire de la glande thyroïde (35% du contrôle), des parois ventriculaires gauche et droite (59 et 50%), de la surrénale (59%), du foie (63%), de la rate (56%), du pancréas (35%), de l’épiploon (20%) et de l’intestin (60%); à 1,5 MAC, la baisse s’accentue dans la thyroïde (15%), les parois ventriculaire gauche et droite (31% et 32%), la surrénale (42%), le foie (47%), la rate (31%), le pancréas (23%), l’épiploon (20%), l’estomac (45%) et l’intestin grêle (54%). On ne note pas de changements au cerveau, au rein, au gros intestin et au muscle squelettique. Le shunt artériolo-veinulaire diminue au rein de 12,1 à 3,8% à 0,75 MAC et à 2,5% à 1,5 MAC. Par contre, avec l’anesthésie à l’isoflurane, le débit capillaire demeure inchangé, a l’exception d’une baisse dans la thyroïde (43%) et la paroi ventriculaire droite (74%) pendant l’anesthésie à 1,5 MAC. Cependant, le shunt artériolo-veinulaire augmente au cerveau de 12,0% à 29,7% et 33,0% respectivement sous isoflurane 0,75 et 1,5 MAC. Il augmente aussi de 25,0% à 41,0% et 46,3% dans le muscle squelettique, et de 8,9% à 19,9% et 17,4% dans la circulation systémique. Ces données montrent que le débit capillaire est mieux préservé pendant l’anesthésie à l’isoflurane que pendant l’anesthésie à l’enflurane, mais que l’anesthésie à l’isoflurane est associée avec une augmentation du shunt artériolo-veinulaire.

Perioperative auto transfusion: haemodilution and red cell salvaging

We have treated 129 cases of massive haemorrhage during surgery using our combined autotransfusion technique (HAT and SAT). No adverse reactions or complications have been noted and additional homologous blood transfusion has not been required. In addition, circulatory dynamics have been satisfactorily maintained. Although the red cell recycle rate has been maintained at over 85%, the salvaging rate of blood in the operating field has not yet reached 80%. Approximately 30% of the surgical haemorrhage appears to be discarded with surgical sponges or flow out of the operating field. Clearly the cooperation of surgeons is an important factor for success with SAT. Success in autotransfusion may be accomplished by combinations of autotransfusion techniques.RésuméEn utilisant une technique per-operatoire combinee d’autotransfusion par hemodilution et recuperation des globules rouges, nous avons reussi a eviler toute transfusion de sang homologue lors de 129 episodes d’hemorragie massive, et ce. sans complication et avec en prime, une stabilite hemodynamique satisfaisante. Toutefois, on perd toujours pres de 30% du saignement dans les eponges ou en dehors du champ operatoire. On peut transfuser intacts au dela de 85% des globules rouges recuperes. Evidemment, la collaboration du chirurgien est essentielle a la recuperation dun maximum de globules rouges.

Approach to Clinical Trial Considering Medical Ethics and Efficacy for HbV, Liposome Encapsulated Hemoglobin Vesicle

Since around 1985, a liposome encapsulated hemoglobin vesicle (HbV) has been developed in Waseda University as an artificial red cell. Subsequently, in 1995, Terumo Co. produced a prototype of HbV for clinical trial, the so–called Neo Red Cell. We tested this in preclinical study and believed firmly that infusion of the HbV could substitute for ordinary blood transfucion [1]. Subsequently, further improvement was done on the HbV by investigators of Waseda and Keio University supported by a grant of Health & Welfare Ministry, Japan, and recent physicochemical properties of the HbV are evaluated, mostly applicable for clinical trial [23].

Pulmonary gas exchange and ventilation-perfusion relationships during hypocapnia and thoracotomy in anaesthetized dogs

The effects of hypocapnia and thoracotomy, both individually and combined, on pulmonary gas exchange and distribution of ventilationperfusion ratio (Va/Q) were studied in anesthetized and paralyzed mongrel dogs by the six inert gas elimination technique. Normocapnia (PaCO2 35 mmHg) and hypocapnia (PaCO2 20 mmHg) were produced sequentially by varying the inspired CO2 concentration. Thoracotomy was performed at the fourth intercostal space. When ventilation was changed from normocapnia to hypocapnia without thoracotomy, PaO2 decreased from 160 ± 10 to 147 ± 11 mmHg and Qs/Qt increased from 0.0 ± 0.0 to 0.6 ± 0.7%. However, no change was observed in perfusion distribution following thoracotomy during normocapnia, PaO2 decreased from 160 ± 10 to 113 ± 15 mmHg together with a shift of perfusion toward the low Va/Q region. However, no change was observed in Qs/Qt. When ventilation was changed from normocapnia to hypocapnia with thoracotomy, PaO2 decreased from 113 ± 15 to 98 ± 12 mmHg and Qs/Qt increased from 0.3 ± 0.8 to 3.4 ± 2.0%. After thoracotomy, a shift of perfusion toward the low Va/Q region was observed, which was probably responsible for the decrease in PaO2. The decrease in PaO2 during hypocapnia was due to an increase in the true shunt rather than the developement of low Va/Q region. Hypocapnia combined with thoracotomy produced a further reduction of PaO2 and a greater increase in Qs/Qt.RésuméLes effets de l’ hypocapnie et la thoracotomie individuellement on combinés sur l’échange vasopulmonaire et la distribution de la ventilation perfusion (Va/Q) furent etudies par la technique de l’elimination des six gaz inertes chez des chiens bâtards anesthésiés et paralysés. La normocapnie (PaCO2 35 mmHg) et l’hypocapnie (PaCO2 20 mmHg) furent produites d’ une façon séquentielle en variant la concentration de CO2 inspirée. La thoracotomie fut faile au quatrieme espace intercostal. Lorsque la ventilation fut changée de la normocapnie à ihypocapnie sans thoracotomie, la PaO2 a diminue de 160 ± 10 à 147 ± 11 mmHg el le Qs/Qt augmenta de 0.0 ± 0.0 à 0.6 ± 0.7%. Cependant, aucun changement ne fut observé dans la distribution de la perfusion. Après thoracotomie tors de la normocapnie, la PaO2 diminua de 160 ± 10 à 113 ± 75 mmHg avec un « shift » de la perfusion vers des regions avant un bas Va/Q. Cependant, aucun changement ne fut observé dans le Qs/Qt. Lorsque la ventilation fut changée de la normocapnie la l’hypocapnie après thoracotomie, la PaO2 diminua de 113 ± 15 à 98 ± 12 mmHg et la Qs/Qt augmenta de 0.3 ± 0.8 à 3.4 ± 2.0%. Aprés thoracotomie, un « shift » de la perfusion vers les regions à bas Va/Q ful observé, ce qui fut responsable de la diminution de la PaO2. La diminution de la PaO2 durant l’hypocapnie était due à une augmentation du shunt vrai plutôt que la création de région de bas Va/Q. L’hypocapnie combinée à la thoracotomie produit une plus grande diminution de la PaO2 et une plus grande augmentation du Qs/Qt.

Influence of nicardipine on post-hypoxic injury in the isolated perfused rat liver☆

We investigated microcirculatory changes and hepatocellular injury due to hypoxia/reoxygenation and the effects of nicardipine, a calcium channel blocker, using the isolated perfused rat liver technique. Liver perfusion was carried out in three consecutive phases: 30-min pre-hypoxia perfusion, 120-min hypoxia perfusion and 30-min reoxygenation perfusion in two groups, a control (n = 5) group and a nicardipine group (n = 5). In the nicardipine group, nicardipine (2 x 10(-6) M) was added to the perfusate prior to the hypoxia perfusion. Intrahepatic volumes, sinusoidal volume and extravascular volume accessible to albumin, were assessed by the multiple indicator dilution technique. Though 120-min hypoxia per se caused only a slight increase in the lactate dehydrogenase (LDH) release and no significant alterations in perfusion pressure and intrahepatic volumes, reoxygenation elicited hepatocellular injury assessed by the LDH level in the perfusate along with a substantial increase in perfusion pressure and an increase in extravascular volume. Nicardipine pretreatment attenuated the increase in LDH level, perfusion pressure and intrahepatic volumes after reoxygenation, but there were no difference in liver microcirculation during 120-min hypoxia. The data of the current study emphasized the crucial role of Ca2+ influx in hypoxic/reoxygenation hepatocellular injury and suggested that a direct vasodilating effect of nicardipine on the intrahepatic vasculature during hypoxia is unlikely as the mechanism for its cytoprotective effects.

Changes in circulating blood volume following isoflurane or sevoflurane anesthesia

Changes of circulating blood volume (CB volume) measured by the dual indicator dilution method were observed in 33 chronically instrumented mongrel dogs following either alpha-chloralose-urethane (C group), additive isoflurane (I group) or sevoflurane anesthesia (S group). These anesthetic groups were each divided into two subgroups with regard to respiratory care, namely Cp, Ip and Sp for those with intermittent positive pressure ventilation (six animals per subgroups), and Cs, Is and Ss for those with spontaneous breathing (five animals per subgroups).The CB volume under positive pressure ventilation remained unchanged in the Ip and Sp groups at both 0.5 and 1.0 MAC, and in the Cp group. The CB volume remained essentially unchanged in the Cs and Is groups at both 0.5 or 1.0 MAC, but the plasma volume tended to increase slightly in the Is group at 1.0 MAC.In the Ss group under spontaneous breathing, however, the CB volume increased from 84.4±7.0 to 91.4±7.7 at 0.5 MAC, and to 91.4±10.2 ml·kg−1 at 1.0 MAC (0.01<P<0.05). These increases were caused by an increase in the plasma volume.The above data suggests that a concomitant increase in the venous pressure associated with an increase in the intrathoracic pressure produced by positive pressure ventilation would attenuate changes in the CB volume during sevoflurane anesthesia.

Effect of hemodilution on capillary and arteriolovenous shunt flow in organs after cardiac arrest in dogs

The purpose of this study was to observe the changes in capillary and arteriolovenous shunting blood flow after cardiac arrest and subsequent resuscitation by venous return occlusion produced by inflation of an intra-atrial balloon and cross-clamping of the ascending aorta, and to determine how hemodilution might modify such changes. Organ capillary blood flow and the fractional distribution of cardiac output were measured by the microsphere (9-microns diameter) trapping method in dogs. Simultaneously, the arteriolovenous shunt rate was measured by continuous collection of venous blood drained at 4.8 ml.min-1 for 2 min from the brain, kidney, liver, splanchnic organs, skeletal muscle of the pelvic limb, and all of the systemic circulatory organs. The capillary blood flow of the brain, thyroid gland, pancreas, and stomach decreased after circulatory arrest in five nonhemodiluted dogs (group C); arteriolovenous shunt rate was unchanged after circulatory arrest in this group. However, with hemodilution, which was induced either before (pre group, n = 5) or after (post group, n = 5) circulatory arrest, no change occurred in the shunt rate in any of the organs, with the exception of an increase in the systemic arteriolovenous shunt rate in the pre group. Capillary blood flow was maintained at almost the same level as before circulatory arrest in the pre group, but increased significantly in several organs of the post group. The data indicated that hemodilution might be effective for prevention of organ ischemia after cardiac arrest.