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)     

Renal failure in haemorrhagic shock in dogs: Salutary effects of the calcium entry blocker felodipine

Summary The efficacy of felodipine, a dihydropyridine calcium entry blocker to restore renal function was investigated in Wiggers model of haemorrhagic shock. Mongrel dogs were anaesthetized with sodium pentobarbital and subjected to haemorrhagic shock by allowing the animals to bleed into a reservoir. After maintaining the hypotensive state (mean blood pressure 40–45 mm Hg) for a period of 150 min, the blood was reinfused and the recovery of the various parameters were monitored for an additional 120 min. These studies were conducted in three different groups of dogs: (A) Solvent control, (B) Felodipine 0.01 mol/kg i. v., administered 10 min prior to reinfusion of the blood, and (C) Felodipine 0.01 mol/kg i. v., administered prior to haemorrhage. In all the three groups arterial blood pressure returned to similar basal levels following reinfusion. Felodipine administration prior to haemorrhage or before reinfusion (Group B and C) resulted in a 80–95% recovery in the renal blood flow, 60–65% in the glomerular filtration rate, 15–300% in the urine volume and 80–100% in the urinary sodium and potassium excretions. In the vehicle-treated control group, despite a 45% recovery in the renal blood flow, renal function was not restored following reinfusion.The observations made in these studies suggest that felodipine, an arteriolar dilator which also possesses natriuretic properties, could be clinically useful in the treatment of renal failure in haemorrhagic shock. Prevention of cellular calcium overload during ischaemia and reperfusion by this dihydropyridine derivative, may account for its ability to preserve vascular as well as tubular function. Send offprint requests to B. S. Jandhyala at the above address     

Optimum dose of epidural morphine for postsurgical analgesia

To determine the optimum dose of epidural morphine for postoperative pain control, 0.5–4.0mg of morphine was administered to 198 patients who had undergone operations on lower abdomen or lower extremities under continuous epidural anesthesia. Analgesic effect of morphine and incidence of nausea or vomiting were studied using linear discriminant analysis. As explanatory variables, age and dose of morphine were statistically significant in discriminating analgesic effect of morphine. Among indices for physique of patients, height was the most useful for predicting the analgesic effect. The dose which made the discriminant function zero corresponded to the minimum effective dose (MED) of morphine and it was expressed as follows; MED (mg·meter^–1) = –0.0107 × age + 1.85. Predicting the incidence of nausea or vomiting in relation to the dose of morphine did not reach a level of statistical significance.(Ochi G, Yamane C, Arai T: Optimum dose of epidural morphine for postsurgical analgesia. J Anesth 4: 35–39, 1990)     

小儿急性白血病骨胳X线表现(附10例分析)

结合10例临床资料分析,认为小儿急性白血病浸润骨骼的主要X线表现为骨质稀疏、干骺端横行透明线,溶骨性破坏,骨膜反应及病理骨折等。上述表现可出现于临床症状之前,对小儿急性白血病的诊断起着重要作用,特别是2岁以上患儿长骨干骺端白血病线是本病诊断的重要依据。     

中西医结合治疗宫外孕(附35例报告)

中西医结合治疗各类型宫外孕35例,应用“活血祛瘀”的原则和方药加减治愈29例,占82.8％,治疗过程中改用手术治疗6例,占17.1％。一般患者服药后3～7天腹痛减轻,腹胀消失。血肿包块消失需1～2月,平均住院26天。是一种治疗简便,疗效显著的方法。     

Estimating the financial savings from maintaining the level of acute services with fewer hospital beds

All district health authorities are obliged to use resources most efficiently. One approach to increasing efficiency is to identify measures which allow service levels, in terms of patients treated and standards of care, to be maintained at a lower cost. This could be achieved by maintaining service levels with fewer hospital beds. Reducing lengths of stay by removing organizational delays and expansions of day-case care, are policies which can increase patient caseload per bed. This paper puts forward an approach for estimating the resources released by such policies and assesses the savings achieved by realizing efficiency gains identified in a previous study by Beech et al. (1987). That study identified significant potential for maintaining services with fewer beds, with the expansion of day-case care being a key mechanism. However this paper concludes that when services are maintained with fewer beds, the vast majority of hospital costs remain fixed. It also reaches the alarming conclusion that as a vehicle for reducing costs, day-case care is much less effective than previous studies have implied. However, increasing hospital throughput per bed does release capacity to treat more patients. The proposed reforms of the NHS (Secretaries of State, 1989) envisage an internal market for health care, allowing hospitals to enter into contracts with purchasers of health care. The approach to costing described in this paper is applicable to assessing the increased costs associated with such developments. These extra costs can then be compared with expected income.     

Behavioral effects of MK-801 in the rat

Several experiments were conducted to study the effects of the noncompetitive N-methyl-d-aspartate (NMDA) receptor antagonist, MK-801, on learning and memory in the rat. Rats displayed impaired performance on several sensorimotor tests and appeared grossly intoxicated when treated IP with 0.2 mg/kg MK-801, but not when treated with lower doses (0.05 or 0.1 mg/kg). Postacquisition performance on two spatial learning tasks involving working memory protocols (reinforced alternation and radial arm maze) was impaired by MK-801 at intoxicating doses (0.2 mg/kg) but not at lower doses (0.05 or 0.1 mg/kg). Using a position habit reversal task, we found that rats could learn to reverse a position habit while under the influence of a nonintoxicating dose of MK-801 (0.1 mg/kg), but when tested on the following day performed as if they did not recall what they had learned. Thus, acute administration of a nonintoxicating dose of MK-801 disrupts the retention of new information learned under the influence of the drug but does not interfere with the performance of tasks that are well learned before the drug is administered. Whether the performance deficits on the spatial learning tasks observed only following intoxicating doses of MK-801 reflect an effect on memory is not clear.     

Evidence for feeding elicited through antihistaminergic effects of tricyclic antidepressants in the rat hypothalamus

We studied central mechanisms of antidepressants that affect feeding behavior in rats. The tricyclic compounds amitriptyline, doxepin and imipramine significantly induced feeding after their infusion into the third cerebral ventricle in the light phase, but the tricyclic, desipramine, and the dicyclic zimelidine, did not. Drinking was not affected by any compound tested. The relative order of potency in eliciting feeding was: amitriptyline and doxepin > imipramine > desipramine and zimelidine. To clarify the involvement of neuronal histamine in antidepressant-induced feeding, alpha-fluoromethylhistidine (FMH), a suicide inhibitor of histidine decarboxylase, was intraperitoneally administered before infusion of amitriptyline. FMH attenuated the amitriptyline's effect. Bilateral microinfusion of amitriptyline into the ventromedial hypothalamus or the paraventricular nucleus verified that these are loci for the modulation of feeding by amitriptyline. In the lateral hypothalamus, amitriptyline was less effective. These findings indicate that tricyclic antidepressants directly facilitate feeding, which is, at least in part, mediated by histamine in the hypothalamus.     

Regional alterations of brain biogenic amines and GABA/glutamate levels in rats following chronic lead exposure during neonatal development

Wistar rat pups were administered either a high dose of lead acetate (400 g lead/g body weight/day) or a low dose (100 g lead/g body weight/day) by gastric intubation, from 2 days through 60 days of age. The rats on both these doses exhibited statistically significant decreases in body and brain weights throughout the lead treatment period. A group of rats on high dose was also rehabilitated by discontinuing the lead from 60 days of age. In these rats, at 160 days of age, the body weight but not the brain weight recovered to normal levels. During the lead intake, the rats on high dose revealed significant elevations in the levels of noradrenaline (NA) in the hippocampus (HI), cerebellum (CE), hypothalamus (HY), brainstem (BS), and accumbens-striatum (SA). The elevated levels in all the above regions except in the HY persisted even after rehabilitation. The dopamine (DA) levels changed significantly in opposite directions in HY (elevation) and BS (reduction) during the lead treatment, and the HY recovered after rehabilitation. Under lead, the serotonin (5HT) levels were elevated significantly in the HI, BS and MC (motor cortex), while after rehabilitation the abnormality persisted only in the MC. Low dose lead treatment was also effective on the same areas of brain. In the low dose group, estimation of the levels of GABA and glutamate were also done, and a significant decrease of GABA in CE and glutamate in MC was observed. The differences observed in the neurotoxic effects (none or significant) of lead in the different regions for each of the transmitters (NA, DA, 5HT) supports the interesting conclusion that the vulnerability of the axon terminals of any given type is dependent on some regional factors, although the projections of the different regions originate from an apparently similar category of neurons in the brain stem.     

Toxicity of lead acetate to female rabbits after chronic subcutaneous administration. 1. Biochemical and clinical effects

The effect of chronic subcutaneous administration of lead acetate was studied in female rabbits. The low-dose group (15 animals) received three times a week 0.10–0.20 g/kg body weight and the high-dose group (15 animals) 0.80–1.20 g/kg. The control group received the vehicle only. Concentrations of lead in blood in the low-dose group increased to ca. 400 g/l after 70 days and in the high-dose group to ca. 900 g/l after 110 days. After 7.5 months eight animals of each group were sacrificed. The remaining rabbits were kept for an additional 4 months without treatment. Blood lead concentrations decreased with a half-time of 60–70 days. During exposure the gain in body weight was lower in the high-dose group than in the control group and the low-dose group. The high-dose group developed slight anaemia and low MCV, MCH and MCHC, and basophilic stippling of erythrocytes. These effects disappeared during recovery. ALAD activity in erythrocytes was very low during exposure in both exposed groups and did not reach control values during recovery. During exposure the concentrations of ZPP and ALA-U increased, but only ALA-U returned to normal during recovery. No other effects of lead on the composition of the urine were observed. No effects were observed on plasma urea and creatinine concentrations. In the highdose group the concentration of ALAD in the liver decreased by 30%. During recovery this effect was no longer present. No effects were seen in cytochrome P-450 content or cytochrome P-450-dependent enzyme activities. Lead was mainly stored in bones, but some also in serveral soft tissues. After recovery the concentrations in soft tissues decreased to a variable degree. In the high-dose group the relative weights of heart and liver increased. These effects disappeared during recovery. At 400 g lead/l blood no adverse effects were observed that did occur at the high dose level.Part 2, dealing with the histopathology and (electron) microscopy of the kidneys is in preparation