Makoto Shiga

The inhibitory effects of thiopental, midazolam, and ketamine on human neutrophil functions.

We investigated the effect of thiopental, midazolam, and ketamine (at clinically relevant concentrations and at 0.1 and 10 times these concentrations) on several aspects of human neutrophil functions. The three intravenous (IV) anesthetics significantly decreased chemotaxis, phagocytosis, and reactive oxygen species (ROS) (O2-, H2 O2, OH) production of neutrophils in a dose-dependent manner. At clinically relevant concentrations, thiopental and midazolam significantly depressed these neutrophil functions. However, ketamine at the clinical plasma concentration did not impair chemotaxis or ROS production, except phagocytosis. In contrast, the three anesthetics had no effect on the levels of ROS production by a cell-free ROS generating system. In addition, intracellular calcium concentrations in neutrophils stimulated by N-formyl-L-methionyl-L-leucil-L-phenylalanine were dose-dependently decreased in the presence of each of the three anesthetics. The suppression of an increase in intracellular calcium concentrations may be responsible for the inhibition of neutrophil functions by the IV anesthetics. Implications: Neutrophils play an important role in the antibacterial host defense system and autotissue injury. We found that thiopental and midazolam (but not ketamine), at clinically relevant concentrations, impaired the neutrophil functions.

Propofol inhibits human neutrophil functions

Neutrophils play important roles in the antibacterial host defense mechanism and in the pathogenesis of tissue injury.Propofol has been reported to impair the production of reactive oxygen species from neutrophils. We examined the effect of propofol (2,6-diisopropylphenol), at clinically relevant concentrations and at 10 and 100 times this concentration, on several aspects of human neutrophil functions using an in vitro system. Propofol significantly inhibited chemotaxis, phagocytosis, and reactive oxygen species (ROS) (O2-, H2 O2, OH) production of neutrophils in a dose-dependent manner. At clinically relevant concentrations, propofol suppressed these neutrophil functions, but it did not decrease ROS generation by the cell-free (xanthine-xanthine oxidase) system. Increase in intracellular calcium concentrations in neutrophils stimulated by N-formyl-L-methionyl-L-leucyl-L-phenylalanine was dose-dependently attenuated by propofol. This decreasing effect on [Ca2+] (i) in neutrophils may represent one of the mechanisms responsible for the inhibition of neutrophil functions by propofol. Implications: Neutrophils play a pivotal role in the antibacterial host defense system and tissue injury. We found that at clinically relevant concentrations, propofol impaired neutrophil functions. Further studies may determine whether this impairment, observed in vitro, leads to clinical immunological suppression. (Anesth Analg 1998;87:695-700)

Clonidine in paediatric anaesthesia

Introduction anaesthesia was available. A prospective study on oral clonidine premedication in children dates from Clonidine, an a2-adrenoceptor agonist, was first 1993 (11). Recently, the number of publications introduced into adult clinical practice as antiindicating effectiveness of clonidine in paediatric hypertensive medication in the late 1960s (1). The anaesthesia has increased and several articles are first application of clonidine to children dates back published annually in anaesthesia journals worldto 1973 (2): an eleven-year-old child received the wide (Figure 1). In this article, we review the drug for migraine. This treatment, which is not present state of clonidine application to paediatric currently used, was based on continuous low doses anaesthesia by focusing on recent investigations, of clonidine reducing the responsiveness of vascular mainly a series of our studies on premedication with smooth muscle to sympathetic nerve activity. Thereafter, clonidine has been used as a provocative test of growth hormone (GH) or treatment for neuropsychiatric disorder (see later section) and in adult patients with migraine or hypertension. However, its use was limited because of adverse side effects including sedation and antisialogogue action, but it is these properties which have been partially responsible for a new enthusiasm for clonidine in anaesthesia. In 1979, clonidine was used experimentally to reduce the dose requirement for anaesthetic and analgesic drugs (3). Not until the late 1980s did several studies demonstrate that clonidine is an effective premedicant in adult patients, providing preoperative sedation (4–7), perioperative haemodynamic stability (8,9), and reduction in the volatile 1997 30

Intravenous lidocaine attenuates acute lung injury induced by hydrochloric acid aspiration in rabbits.

Background Neutrophils play a crucial role in the pathogenesis of acid‐induced acute lung injury. Lidocaine inhibits the function of neutrophils. This study aimed to determine whether lidocaine attenuates acute lung injury induced by hydrochloric acid (HCl) instillation. Methods In study 1, rabbits were divided into four groups (n = 7 each). Lung injury was induced by intratracheal HCl (0.1 N, 3 ml/kg) in two groups. The other two groups received saline intratracheally. Lidocaine given intravenously (2 mg/kg bolus + 2 mg [center dot] kg‐1 [center dot] h‐1 infusion) was started 10 min before intratracheal instillation in one HCl and one saline group, and saline was given intravenously in the other two groups. In study 2, rabbits (four groups of seven animals each) received HCl (0.1 N, 3 ml/kg) intratracheally. Treatment with intravenous lidocaine was started 10 min before, 10 min after, or 30 min after acid instillation, or saline was given intravenously 10 min before instillation. Results In study 1, HCl caused deterioration of the partial pressure of oxygen (PaO2), lung leukosequestration, decreased lung compliance, and increased the lung wet‐to‐dry weight ratio and albumin, interleukin‐6 (IL‐6), and IL‐8 levels in bronchoalveolar lavage fluid. Lidocaine pretreatment attenuated these changes. Hydrochloric acid increased superoxide anion production by neutrophils and caused morphologic lung damage, both of which were lessened by lidocaine. In study 2, lidocaine given 10 min after acid instillation was as effective as pretreatment in PaO2, lung mechanics, and histologic examination. However, PaO2 changes in lidocaine 30 min after injury were similar to those in saline given intravenously. Conclusions Intravenous lidocaine started before and immediately after acid instillation attenuated the acute lung injury, in part by inhibiting the sequestration and activation of neutrophils.

ONO-5046, an elastase inhibitor, attenuates endotoxin-induced acute lung injury in rabbits.

Endotoxin causes acute lung injury resembling acute respiratory distress syndrome.Elastase, as well as reactive oxygen species released from activated neutrophils, are thought to play pivotal roles in the pathogenesis of this lung injury. This study investigated whether ONO-5046, a specific elastase inhibitor, can attenuate acute lung injury induced by endotoxin in rabbits. Thirty-two male anesthetized rabbits were randomly assigned to receive one of four treatments (n = 8 for each group): infusion of saline without ONO-5046 treatment (Group S-S), infusion of saline with ONO-5046 (Group S-O), infusion of Escherichia coli endotoxin (100 micro g/kg over 60 min) without ONO-5046 (Group E-S), and infusion of endotoxin with ONO-5046 (Group E-O). Fifteen minutes before the infusion of endotoxin (Groups E-O and E-S) or saline (Groups S-S and S-O), the animals received a bolus injection of ONO-5046 (10 mg/kg) followed by continuous infusion (10 mg [centered dot] kg-1 [centered dot] h (-1): Groups S-O and E-O) or saline (Groups S-S and E-S). The lungs of the rabbits were ventilated with 40% oxygen. Hemodynamics, peripheral leukocyte and platelet counts, and PaO2 were recorded during the ventilation period (6 h). Lung mechanics, cell fraction of the bronchoalveolar lavage fluid (BALF), activated complement, cytokines, and arachidonic acid metabolite concentrations in the BALF were measured at 6 h. The wet- to dry (W/D)-weight ratio of the lung and albumin concentrations in BALF were analyzed as indices of pulmonary edema. Endotoxin decreased lung compliance and PaO2, and increased the W/D weight ratio, neutrophil counts, and albumin concentration in the BALF. Concentrations of activated complement C5a, interleukin-6, interleukin-8, and thromboxane B2 in the BALF were increased by the infusion of endotoxin. ONO-5046 treatment attenuated these changes. Endotoxin caused extensive morphologic lung damage, which was lessened by ONO-5046. In conclusion, intravenous ONO-5046 pretreatment attenuated endotoxin-induced lung injury in rabbits. This beneficial effect of ONO-5046 may be due, in part, to a reduction in the levels of mediators that activate neutrophils, in addition to the direct inhibitory effect on elastase. (Anesth Analg 1997;84:1097-103)

Therapeutic time-window of a group IIA phospholipase A2 inhibitor in rabbit acute lung injury: correlation with lung surfactant protection.

ObjectiveWe attempted to determine whether group IIA secretory phospholipase A2 (sPLA2-IIA) blockade after the onset of lung injury exerted therapeutic efficacy in the treatment of oleic acid (OA)-induced acute lung injury by using S-5920/LY315920Na, a novel specific inhibitor of sPLA2-IIA, with special interest in the changes of lung surfactant. DesignProspective animal study. SettingUniversity laboratory. SubjectsForty Japanese white rabbits. InterventionsThe rabbits, under anesthesia, were endotracheally intubated and mechanically ventilated and then were divided into the following groups: OA + vehicle groups, intravenous infusion of OA for the first 2 hrs (0.1 mL·kg−1·hr−1) with the addition of vehicle (1 or 2 hrs after OA administration, each n = 9, total 18 rabbits); OA + S-5920/LY315920Na groups, treated identically to the OA control with the addition of S-5920/LY315920Na (1 mg/kg bolus followed by infusion at 0.5 mg·kg−1·hr−1) after OA (1 or 2 hrs after OA administration, each n = 9, total 18 rabbits); saline control groups, treated with saline instead of OA with the addition of vehicle (1 hr after OA administration, 4 rabbits). Arterial blood gas, lung mechanics, lung inflammation, lung surfactant phospholipids, and production of inflammatory mediators in the lung were measured. Measurements and Main Results Treatment with S-5920/LY315920Na 1 hr after OA infusion, but not 2 hrs after infusion, significantly attenuated the lung injury, as estimated by hypoxemia, decreased lung compliance, pulmonary edema, and vascular permeability. The therapeutic efficacy was similar to that found in our previous pretreatment study. The treatment after 1 hr dramatically inhibited OA-induced surfactant degradation in the bronchoalveolar lavage fluid (BALF), without affecting the concentrations of thromboxane A2, leukotriene B4, and interleukin-8 in BALF. The degree of surfactant degradation in BALF paralleled well with the severity of the lung injury. Furthermore, recombinant human sPLA2-IIA reproduced the similar hydrolysis pattern of isolated surfactant in vitro, which was inhibited by S-5920/LY315920Na. ConclusionsOur results indicate that therapeutic blockade of sPLA2-IIA ameliorated lung dysfunction via protection of surfactant degradation in an animal model of acute lung injury, and they suggest a new strategy in treating clinical acute lung injury.

The Effects of Clonidine and Dexmedetomidine on Human Neutrophil Functions

UNLABELLED Neutrophil functions are inhibited by various anesthetics. Clonidine and dexmedetomidine, alpha2-agonists, are often used as adjuncts to anesthesia. Thus, we conducted the current study to determine the effect of clonidine, dexmedetomidine, and xylazine at clinically (or veterinary anesthetically) relevant concentrations (and 10 and 100 times these concentrations) on several aspects of human neutrophil functions using an in vitro system. The three alpha2-agonists had no effects on chemotaxis, phagocytosis, or superoxide anion (O2-) production of neutrophils, except that the highest concentration of clonidine inhibited chemotaxis. Increases in intracellular calcium concentrations in neutrophils stimulated by chemotaxin were not influenced by clonidine, dexmedetomidine, or xylazine. Unchanged calcium concentrations may contribute to failure to modulate the neutrophil functions. In addition, these drugs did not scavenge O2- generated by the cell-free (xanthine-xanthine oxidase) system. This is the first report concerning the effect of clonidine or dexmedetomidine on human neutrophil functions. Our findings suggest that we may not have to take extra precautions in using the alpha2-agonists in patients with infection, but that we cannot expect these drugs to be prophylaxis against autotissue injuries whose pathogenesis includes activation of neutrophils. IMPLICATIONS Neutrophils are involved in the antibacterial host defense system and autotissue injury. We found that clinically relevant concentrations of clonidine and dexmedetomidine do not affect chemotaxis, phagocytosis, or superoxide production by human neutrophils. These findings indicate that it may not be necessary to take special care in using alpha2-agonists in patients with infection, sepsis, or systemic inflammation.

Inhibitory effect of local anaesthetics on reactive oxygen species production by human neutrophils

Background: Reactive oxygen species (ROS) generated from neutrophils accumulated in various major organs are thought to play a pivotal role in the pathogenesis of host auto‐injury. Lidocaine has been shown to reduce the injury. We investigated the effect of local anaesthetics (lidocaine, mepivacaine and bupivacaine) on ROS production by neutrophils using an in vitro system.

A Comparison of Lansoprazole, Omeprazole, and Ranitidine for Reducing Preoperative Gastric Secretion in Adult Patients Undergoing Elective Surgery

Acid aspiration syndrome of induction of anesthesia is a life-threatening complication whose severity is affected by both pH and volume of the aspirated gastric juice. We compared the effects of two proton pump inhibitors (PPIs), lansoprazole and omeprazole, and an H2 blocker, ranitidine, on gastric secretion in a prospective, randomized, double-blind fashion in 200 adult patients of ASA physical status I under-going elective surgery. The patients were divided into eight groups (n = 25 each) according to their premedication. The patients received lansoprazole-lansoprazole (Group L-L), lansoprazole-placebo (Group L-P), placebo-lansoprazole (Group P-L), omeprazole-omeprazole (Group O-O), omeprazole-placebo (Group O-P), placebo-omeprazole (Group P-O), placebo-ranitidine (Group P-R), or placebo-placebo (Group P-P) as the first and second medications. The dose of the study drug was 30 mg for lansoprazole, 150 mg for ranitidine, and 80 mg for omeprazole. The first medication was administered orally at 9:00 PM on the night before surgery and the second at 5:30 AM in the morning on the day of surgery. Each patient fasted overnight and took the drug with 20 mL of water. After tracheal intubation, gastric fluid was aspirated via an orogastric tube and the volume and pH of the aspirate were measured. The pH of the aspirated gastric fluid was higher in Groups P-R, L-L, P-L, O-O, and O-P than in Group P-P (P < 0.05). The volume of the gastric contents was similar in Groups P-O and P-P, and the other groups had smaller gastric volume than Group P-P (P < 0.05). Gastric fluid from patients in Group P-R was the least acidic (pH 6.1 +/- 1.2) and had the least volume (0.09 +/- 0.06 mL/kg). Group L-L was comparable with Group P-R in both pH and volume, whereas Groups P-L and O-O were similar to Group P-R only in volume. The proportion of patients at risk according to the traditional criteria (pH <2.5 and volume >0.4 mL/kg) was significantly lower in Groups L-L (0%), P-L (4%), O-O (4%), and P-R (0%) than in Group P-P (48%) (P < 0.05). We concluded that two consecutive doses of lansoprazole or a morning dose of ranitidine seemed to be the most effective preanesthetic medication for reducing gastric acidity and volume. (Anesth Analg 1996;82:832-6)

Oral clonidine premedication reduces minimum alveolar concentration of sevoflurane for tracheal intubation in children.

Background: Sevoflurane is a useful anesthetic for inhalational induction in children because of its low solubility in blood and relatively nonpungent odor. Clonidine has sedative and anxiolytic properties and reduces the requirement for inhalation agents. Nitrous oxide (N2 O) also decreases the requirement of inhaled anesthetics, but the effect is variable. The minimum alveolar concentration for tracheal intubation (MACTI) of sevoflurane was assessed with and without N2 O and clonidine premedication. Methods: Seventy‐two patients, aged 3–11 yr, were assigned to one of six groups (n = 12 each). They received one of three preanesthetic medications (two groups for each premedication): placebo (control), 2 micro gram/kg oral clonidine or 4 micro gram/kg oral clonidine. In one group of each premedication, anesthesia was induced with sevoflurane in oxygen; in the other group, anesthesia was induced with sevoflurane in the presence of 60% N2 O. Each concentration of sevoflurane at which tracheal intubation was attempted was predetermined according to Dixons up‐and‐down method and held constant for at least 20 min before the trial. Results: The MACTI of sevoflurane in the absence of N2 O (mean +/‐ SEM) was 3.2 +/‐ 0.2%, 2.5 +/‐ 0.1%, and 1.9 +/‐ 0.2% in the control, 2‐micro gram/kg clonidine, and 4‐micro gram/kg clonidine groups, respectively. Nitrous oxide (60%) decreased the MACTI of sevoflurane by 26%, 24%, and 27% in the control, 2‐micro gram/kg clonidine, and 4‐micro gram/kg clonidine groups. Conclusions: Oral clonidine premedication decreased the MACTI of sevoflurane. Nitrous oxide also decreased the MACTI. The combination of clonidine and N2 O lessened the MACTI of sevoflurane more than did either drug alone.