Evaluation of conventional weaning criteria in patients with acute respiratory failure

We evaluated the reliability of conventional weaning criteria from a ventilator during 33 weaning trials on 25 patients with acute respiratory failure (ARF). Of 13 criteria, a ratio of maximal voluntary ventilation to minute ventilation (MV) 2, a vital capacity 12ml·kg^–1, a spontaneous respiratory rate 25 breaths·min^–1, and a MV 10l·min^–1 appeared to be useful for predicting successful weaning outcome. However, even using those criteria, there were many falsely-negative cases. The alveolar-arterial P_{O 2} gradient 350mmHg at an Fi _{O 2} 1.0 was not useful as a predictor of weaning outcome. The present study demonstrates that conventional criteria are frequently inaccurate for predicting weaning outcomes and suggests that the use of some of these criteria may unnecessarily prolong the length of ventilator support. Since ventilation of most patients with poor oxygenation can be successfully discontinued by placing them on a continuous positive airway pressure system, these results suggest that the improvement of oxygenation is not an indispensable prerequisite for weaning from mechanical ventilators.(Okamoto K, Iwamasa H, Dogomori H, et al.: Evaluation of conventional weaning criteria in patients with acute respiratory failure. J Anesth 4: 213–218, 1990)     

Solute Absorption from the Airways of the Isolated Rat Lung. IV. Mechanisms of Absorption of Fluorophore-Labeled Poly-α,β-[N(2-Hydroxyethyl)-DL-Aspartamide]

The pulmonary absorption kinetics of a single molecular weight distribution (MWD) of fluorophore-labeled poly-,-[N(2-hydroxyethyl)-DL-aspartamide] (F-PHEA), a hydrophilic and biocompatible synthetic polypeptide, were studied in the isolated, perfused rat lung (iprl) as functions of administered polymer concentration, dose, vehicle, and presence and absence of fluorophore. The MWD was characterized before and after absorption by measurement of weight- and number-averaged molecular weights (M _wand M _n, respectively) using high-performance gel-permeation chromatography. Values for M _w and M _n were 8.6 and 5.3 kD before, and 6.7 and 4.7 kD after, absorption into the perfusate; there was no significant metabolism and the MWD of the absorbed polymer was independent of both dose and sampling time over a 3-hr period. F-PHEA failed to show any evidence of aggregation in solution or changes in dose distribution within the airways as functions of increasing polymer concentration and dose. A concentration ranging study indicated the presence of a saturable, carrier-mediated transport process for F-PHEA with a maximum absorption rate, V _max, of approximately 180 µg or 0.027 µmol/hr. Coadministration of fluorophore-free PHEA was capable of depressing the absorption of F-PHEA. The transport process for F-PHEA appeared to have a molecular weight limit of about 7 kD for this hydrophilic polymer.     

Breast parenchymal activity on scintimammography: Comparison between bone-seeking agents and99mTc-sestamibi

The aim of this study was to evaluate breast parenchymal activity on scintimammography with bone-seeking agents and 99mTc-MIBI. Scintimammography was performed with bone-seeking agents in 61 patients and with 99mTc-MIBI in 33 patients. Activity in the breast parenchyma contralateral to the suspected lesion was visually assessed by two independent observers. Increased breast parenchymal activity was shown in 19 of 61 patients examined with bone-seeking agents, while it was demonstrated in only two of 33 patients examined with 99mTc-MIBI. Breast parenchymal activity of bone-seeking agents was higher in patients aged 50 years or younger than in those older than 50. Increased parenchymal activity of bone-seeking agents may disturb visualization of primary breast cancer especially in relatively young patients. Low parenchymal activity is suggested to be a favorable characteristic of 99mTc-MIBI as a scintimammographic agent.     

Primary anorectal malignant melanoma: Report of a case

(Received for publication on Aug. 18, 1997; accepted on May 15, 1998)     

Vasogenic edema on MELAS: a serial study with diffusion-weighted MR imaging

The authors performed a serial study of a patient with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like syndrome (MELAS) who presented with diffusion-weighted MRI (DWI). DWI demonstrated a higher apparent diffusion coefficient in the lesion than in the control region during the acute stage of stroke. Vasogenic edema is present in stroke-like episodes in MELAS.     

Origin of the "N10" stationary-field potential after median nerve stimulation.

The scalp far-field potentials after median nerve stimulation at the wrist consist of P9, P11, P13, and P14 positive components. Earlier, Emerson et al. (1984) identified the "N10" negative potential in-between the P9 and P11 and claimed that this was not merely a passive return to the baseline after the P9 positive deflection but a distinct component reflecting a proximal brachial plexus volley. They thought N10 was a far-field potential having widespread distribution with a fixed latency. In this study we found that N10 was of higher amplitude after median nerve stimulation at the elbow than after stimulation at the wrist. Indeed the N10 latency was fixed from the lower anterior neck to the scalp, and its amplitude was maximum at the anterior lower neck. The latency of N10 was about 0.3 milliseconds longer than the Erb's potential and 0.15 milliseconds longer than the potential recorded from the lateral neck on the side of stimulation. The N10 amplitude increased in parallel with increased stimulus intensity. In order to explore the origin of the N10 stationary field potential, we designed a paired stimuli paradigm applied to the wrist (S1) and to the elbow (S2). The interstimulus interval between S and S2 was adjusted so that the timing of S2 was immediately after the traveling impulse produced by the S1 stimulus as it passed through the S2 stimulus site. This technique allowed stimulation of the anterior interosseous nerve selectively at the elbow while the median nerve originating from the wrist was undergoing refractory period. The response of (S1 + S2) - S1 showed only the N10 with absence of cervical and cortical responses, implying that N10 was activated, predominantly by the interosseous nerve, i.e., an antidromic motor volley, when the median nerve was stimulated at the elbow.     

Influence of antigenic forms and adjuvants on the IgG subclass antibody response to Aujeszky's disease virus in mice.

The influence of antigenic forms of Aujeszky's disease virus (ADV) and adjuvant types on the production of IgG subclass antibodies in mice was investigated. Particulate antigen, inactivated ADV, alone induced IgG1 and lower IgG2a antibody production, while the antigen adsorbed onto aluminum phosphate gel (alum) enhanced IgG1 antibody production but suppressed IgG2a antibody production as well as solubilized ADV antigen adsorbed onto alum. QS21 saponin purified from Quillaja saponaria promoted the production of IgG1 and IgG2a antibodies in a large extent against the both particulate and soluble antigens, while this saponin has strong hemolytic activity. Lablaboside F saponin isolated from Dolichos lablab without hemolytic activity, also induced the production of large IgG1 and little IgG2a antibody against both antigens. Oil-based adjuvant, ISA70 of water-in-oil type and ISA25 of oil-in-water type, increased IgG1 and IgG2a antibodies against the both soluble and particulate antigens, whereas a combination of ISA25 and soluble antigen reduced IgG2a antibody response. These results indicate that IgG1 antibody production was not suppressed by a combination of antigenic form and adjuvant type, however, IgG2a antibody production was influenced.     

E5531, a synthetic non-toxic lipid A derivative blocks the immunobiological activities of lipopolysaccharide.

1. The major pathological responses to Gram-negative bacterial sepsis are triggered by endotoxin or lipopolysaccharide. As endotoxin is shed from the bacterial outer membrane, it induces immunological responses that lead to release of a variety of cytokines and other cellular mediators. As part of a program aimed at developing a therapeutic agent for septic shock, we have developed E5531, a novel synthetic lipopolysaccharide antagonist. 2. As measured by release by tumour necrosis factor-alpha, human monocytes or whole blood can be activated by lipopolysaccharide, lipid A, and lipoteichoic acid (from Gram-positive bacteria). E5531 potently antagonizes activation by all these agents while itself being devoid of agonistic activity. 3. The inhibitory activity of E5531 was dependent on time of addition. When 10 nM E5531 was added simultaneously with lipopolysaccharide or 1 - 3 h before addition of lipopolysaccharide, production of tumour necrosis factor-alpha was inhibited by more than 98%. The addition of E5531 1 h after lipopolysaccharide reduced the efficacy of E5531 by 47%. 4. Antagonistic activity of E5531 was specific for lipopolysaccharide as it was ineffective at inhibiting interferon-gamma mediated NO release of RAW 264.7 cells, phorbor 12-myristate 13-acetate stimulated superoxide anion production in human neutrophils, concanavalin A stimulated mitogenic activity in murine thymocytes and tumor necrosis factor-alpha induced E-selectin expression in human umbilical vein endothelial cells. 5. E5531 as well as MY4, an anti-CD14 antibody, inhibited radiolabelled lipopolysaccharide binding in human monocytes. 6. These results support our contention that E5531 is a potent antagonist of lipopolysaccharide-induced release of tumour necrosis factor-alpha and other cellular mediators and may be an effective therapeutic agent for human septic shock due to Gram-negative bacteria.     

Delayed administration of ethyl eicosapentate improves local cerebral blood flow and metabolism without affecting infarct volumes in the rat focal ischemic model.

The objective of this study was to assess whether delayed administration of ethyl eicosapentate has a favorable effect on cerebral blood flow and metabolism in rats suffering from cerebral infarction. Adult male Sprague-Dawley rats weighing 250-300 g were used. Left middle cerebral artery occlusion was induced for 2 h. After 24-h reperfusion, rats were treated with ethyl eicosapentate (100 mg kg(-1); ethyl eicosapentate treated) or saline (saline treated) by gavage, once a day for 4 weeks. After 4 weeks, local cerebral blood flow and local cerebral glucose utilization were measured autoradiographically, and infarction size was measured. In the ischemic side, the local cerebral blood flow and local cerebral glucose utilization values in the parietal cortex and the lateral caudoputamen, which constituted the ischemic core, were equivalent to zero in both groups. The peri-infarcted areas, i.e., the frontal cortex and medial caudoputamen, were significantly higher in the ethyl eicosapentate treated group than the saline treated group. In the non-ischemic side, ethyl eicosapentate treated group had a tendency to improve local cerebral blood flow and local cerebral glucose utilization values in a medial caudoputamen. These results suggest that ethyl eicosapentate treatment may be beneficial for maintaining cerebral circulation and metabolism except for infarction area after cerebral infarction.