Neuromuscular complications in patients given Pavulon (pancuronium bromide) during artificial ventilation

This paper reports on 12 patients in a 3-year period (from 1st July 1980 to 1st July 1983) who were treated with artificial ventilation and with the muscle relaxant pancuronium bromide (Pavulon), over a period of 6 days or longer. After discontinuation of this drug these patients developed severe tetraparesis with areflexia, sometimes combined with disturbances of the extraocular and facial muscles and diffuse muscular atrophy, without sensory disturbances. Seven patients recovered completely after 2-5 months, two made an incomplete recovery and three died due to the primary disease. It is suggested that these neuromuscular complications were caused by prolonged high-dosage Pavulon treatment in combination with renal and hepatic disturbances and/or the use of aminoglucosides.     

Structure,function and evolution of the gas exchangers: comparative perspectives

Over the evolutionary continuum, animals have faced similar fundamental challenges of acquiring molecular oxygen for aerobic metabolism. Under limitations and constraints imposed by factors such as phylogeny, behaviour, body size and environment, they have responded differently in founding optimal respiratory structures. A quintessence of the aphorism that 'necessity is the mother of invention', gas exchangers have been inaugurated through stiff cost-benefit analyses that have evoked transaction of trade-offs and compromises. Cogent structural-functional correlations occur in constructions of gas exchangers: within and between taxa, morphological complexity and respiratory efficiency increase with metabolic capacities and oxygen needs. Highly active, small endotherms have relatively better-refined gas exchangers compared with large, inactive ectotherms. Respiratory structures have developed from the plain cell membrane of the primeval prokaryotic unicells to complex multifunctional ones of the modern Metazoa. Regarding the respiratory medium used to extract oxygen from, animal life has had only two choices--water or air--within the biological range of temperature and pressure the only naturally occurring respirable fluids. In rarer cases, certain animals have adapted to using both media. Gills (evaginated gas exchangers) are the primordial respiratory organs: they are the archetypal water breathing organs. Lungs (invaginated gas exchangers) are the model air breathing organs. Bimodal (transitional) breathers occupy the water-air interface. Presentation and exposure of external (water/air) and internal (haemolymph/blood) respiratory media, features determined by geometric arrangement of the conduits, are important features for gas exchange efficiency: counter-current, cross-current, uniform pool and infinite pool designs have variably developed.     

The fate of diesel hydrocarbons in soils and their effect on the germination of perennial ryegrass

Hydrocarbon contamination in soils may be toxic to plants and soil microorganisms and act as a source of groundwater contamination. The objective of this study was to evaluate the fate of diesel in soils with or without added nutrients. The soils examined either had or had not a previous history of hydrocarbon contamination. Particular aspects examined were soil respiration, changes in microbial population, breakdown of diesel hydrocarbons, and phytotoxicity to the germination of perennial ryegrass. Soil respiration was measured as evolved CO2. Bacterial population was determined as colony forming units in dilution plates and fungal activity was measured as hyphal length. The fate of individual hydrocarbons was determined by gas chromatography-mass spectrometry after extraction with dichloromethane. When diesel was added to soil with no previous history of hydrocarbon contamination at rates up to 50 mg/g, the respiration response showed a lag phase of 6 days and maximum respiration occurred at day 11. The lag phase was 2 days and maximum respiration occurred at day 3 in soil with a previous history of hydrocarbon contamination. After the peak, respiration decreased up to about 20 days in both soils. Thereafter, respiration become more or less constant but substantially greater than the control. N and P addition along with diesel did not reduce the lag phase but increased the respiration over the first 20 days of incubation. Diesel addition with or without N and P increased the bacterial population 10- to 100-fold but fungal hyphal length did not increase. Diesel addition at a rate of 136 mg/g did not increase the microbial population. Removal of inhibition to germination of perennial ryegrass was linked to the decomposition of nC10 and nC11 hydrocarbons and took from 11 to 30 days at diesel additions up to 50 mg/g depending on the soil. Inhibition to germination of perennial ryegrass persisted to more than 24 weeks at the 136 mg/g of diesel addition.     

Axonal projections of pulmonary slowly adapting receptor relay neurons in the rat

We elucidated efferent projections of second-order relay neurons (P-cells) activated by afferents originating from slowly adapting pulmonary receptors (SARs) to determine the central pathway of the SAR-evoked reflexes. Special attention was paid to visualizing the P-cell projections within the nucleus tractus solitarii (NTS), which may correspond to the inhibitory pathway from P-cells to second-order relay neurons (RAR-cells) of rapidly adapting pulmonary receptors. P-cells were recorded from the NTS in Nembutal-anesthetized, paralyzed, and artificially ventilated rats. First, we used electrophysiological methods of antidromic mapping and showed that the majority of the P-cells examined projected their axons to the caudal NTS and to the dorsolateral pons corresponding to the parabrachial complex. Second, a mixture of HRP and Neurobiotin was injected intracellularly or juxtramembranously into P-cells. (1) Stained P-cells (n = 7) were located laterally to the solitary tract and had dendrites extending characteristically along the lateral border of the solitary tract. (2) All P-cells had stem axons projecting to the ipsilateral medulla. Of these, the axons from five P-cells projected to the nucleus ambiguus and its vicinity with distributing boutons. Some of these axons further ascended in the ventrolateral medulla, and distributed boutons in the areas ventral or ventrolateral to the nucleus ambiguus. (3) All the P-cells had axonal branches with boutons in the NTS area. In particular, axons from three P-cells projected bilaterally to the medial NTS caudal to the obex, i.e., to the area of RAR-cells. These results show anatomic substrates for the connections implicated in the P-cell inhibition of RAR-cells as well as the SAR-induced respiratory reflexes.     

不同睡眠时相对正常人呼吸控制功能的影响

目的了解不同睡眠时相对正常人呼吸控制功能的影响.方法通过鼻罩经鼻测定11例正常人在非快动眼睡眠(NREM)Ⅰ Ⅱ、NREMⅢ Ⅳ及快动眼睡眠(REM)睡眠期的口腔阻断压(P0.1),呼吸中枢对低氧及高二氧化碳的反应性.结果在各睡眠时相,P0.1均与清醒时无明显差异(P＞0.05),有效吸气阻抗(P0.1·VT-1·Ti-1)均升高(P＜0.05);在NREM睡眠期,低氧及高二氧化碳通气反应(△VE/△SaO2、△VE/△PaCO2)降低(P＜0.05),但P0.1的低氧及高二氧化碳反应(△P0.1/△SaO2、△P01/△PaCO2)均维持在清醒时的水平(P＞0.05);进入REM睡眠期,△P01/△SaO2、△P0.1/△PaCO2及△VE/△SaO2、△VE/△PaCO2均降低(P＜0.05).结论睡眠时,正常人呼吸中枢对上气道阻力增加可产生较有效的代偿,呼吸驱动(P0.1)维持在清醒时水平;在NREM睡眠期,呼吸中枢的化学敏感性降低不明显;进入REM睡眠期后,中枢的化学敏感性降低,易出现呼吸紊乱.     

Respiratory and behavioural compensation during chronic severe loading in a hypoxic rat model

1. Respiratory load compensation plays an important role in the maintenance of an appropriate level of ventilation. We investigated the ventilatory and behavioural responses to a severe load causing both hypercapnia and hypoxaemia in a rat model. 2. A thin silicone tube (15 mm in length, 1 mm ID) was implanted surgically in the trachea. Arterial blood gases and ventilatory and motor activities were assessed serially and non-invasively over a period of 8 weeks. 3. Ventilatory loading produced severe respiratory acidosis with concomitant hypoxaemia immediately after imposition of the load, but there was a considerable improvement of arterial blood gases at 1 day after the start of respiratory loading. Ventilatory loading also caused a gradual increase in ventilatory activity, requiring 7 days to reach the maximum level. There was a reduction in daily motor activity immediately after the ventilatory loading, but this reduction recovered gradually, together with recovery of reduced food and water intake. Administration of a hyperoxic gas mixture during the ventilatory loading decreased ventilatory activity while improving reduced motor activity. 4. These observations suggest that severe chronic ventilatory loading may induce adaptive responses that compensate rapidly for the disturbed acid-base balance with slow and gradual increases in ventilatory activity while matching the increase in motor activity/metabolic rate.     

Comparative provocation test of respiratory monitoring methods

Objective.The aim of this study was to compare clinicallyrelevant performance of: 1) a prototype respiratory sensor based oncapnometry with two alternative signal receptor fixations, 2) afiberoptic humidity sensor and 3) human visual observation. Comparativeprovocation tests were performed on volunteers at the Post-AnesthesiaCare Unit at Västerås Central Hospital. Methods.Theexperimental tests involved 10 healthy, voluntary test subjects,instructed to intersperse normal breathing with protocol provocations ofbreath holding, limb and head movements, and nasal oxygen supplement.The signal outputs from the three respiratory monitoring methods wererecorded on a personal computer. The signal analysis included visualcategorising of the signals and counting breath events. Recognising thatnone of the methods could act as reference, events were classified asunanimous, majority orminority events depending on how many of the three methodsthat detected a breath. Results.The average total recording timewas 37 minutes per subject. The respiratory rates varied from 6.5 to 19breaths per minute, with a mean value of 11.4 breaths/minute. The breathhold duration ranged from 18 to 50 seconds. Discrepancies between thethree methods were found in more than 20% of the marked events.The most frequent majority events were due to events not recorded by theobserver who, on the other hand, contributed the least to minorityevents. The provocations made by the subjects during the measurement didnot increase the rates of majority and minority events, compared toperiods of no provocation. The fiberoptic device exhibited a largercount of minority events but a smaller contribution to majority eventsthan the capnometry prototype. Conclusions.The capnometry andfiberoptic sensors exhibit differences in responses that may beunderstood from basic principles. The importance of the physicalapplication of the sensor to the patient was clearly observed. Theoptimum design remains to be found.     

Non-linear behaviour of respiratory movement in obstructive sleep apnoea syndrome

In this study we investigated the non-linear properties of respiratory movement in patients with obstructive sleep apnoea syndrome (OSAS) during sleep without and with nasal continuous positive airway pressure (nCPAP). To calculate the correlation dimension (D2) in respiratory movement we applied an algorithm proposed by Grassberger and Procaccia. Non-linearity in respiratory movement was tested by comparing D2 for the original data with that for surrogate data. Respiratory movement was recorded from 10 patients with OSAS. D2 during both wakefulness with eyes closed and during sleep with nCPAP at 8 cm H2O could be computed in all subjects (2.50 +/- 0.69 and 1.68 +/- 0.17, respectively). On the other hand, D2 during sleep with apnoea could not be computed in patients with severe OSAS. These results indicate the abnormal properties of respiratory movement during apnoeic sleep in severe OSAS. Moreover, respiratory movement with nCPAP was shown to be non-linear deterministic behaviour in respiratory movement during sleep. Analysis of D2 for respiratory movement may be useful in adjusting (titrating) nCPAP and classifying severity in OSAS.     

Interlaboratory study for the validation of an ecotoxicological procedure to monitor the quality of septic sludge received at a wastewater treatment plant

Septic tank sludge is regularly hauled to the Montreal Urban Community (MUC) wastewater treatment plant. It is then discharged and mixed with the wastewater inflow before entering the primary chemical treatment process. An ecotoxicological procedure integrating chemical and toxicological analyses has been recently developed and applied to screen for the illicit discharge of toxic substances in septic sludge. The toxicity tests used were the Microtox, the bacterial-respiration, and the lettuce (Lactuca sativa) root elongation tests. In order to validate the applicability of the proposed procedure, a two-year interlaboratory study was carried out. In general, the results obtained by two independent laboratories (MUC and the Centre d'expertise en analyse environnementale du Quebec) were comparable and reproducible. Some differences were found using the Microtox test. Organic (e.g., phenol and formaldehyde) and inorganic (e.g., nickel and cyanide) spiked septic sludge were detected with good reliability and high efficiency. The relative efficiency to detect spiked substances was > 70% and confirms the results of previous studies. In addition, the respiration test was the most efficient toxicological tool to detect spiked substances, whereas the Microtox was the least efficient (< 15%). Efficiencies to detect spiked contaminants were also similar for both laboratories. These results support previous data presented earlier and contribute to the validation of the ecotoxicological procedure used by the MUC to screen toxicity in septic sludge.     

PROGNOSIS OF NEONATES WITH SYMPTOMATIC RESPIRATORY INSUFFICIENCY SURVIVING WITH THE AID OF VENTILATOR THERAPY

ABSTRACT. Twenty-one survivors representing all survivors of neonatal symptomatic respiratory distress treated with intermittent positive pressure ventilation have been followed-up at an age of 2.9 to 7.0 years. The chance of survival proved to be relatively favourable in infants ventilated for perinatal pneumonias and unfavourable in infants ventilated for haemorrhagic diseases and respiratory insufficiency secondary to surgical conditions. At the follow-up half of the children presented with neurological symptoms but only 10% were found severely handicapped. One infant had a tracheostomy due to a laryngeal stenosis, while none developed broncho-pulmonary dysplasia. The late prognosis seemed unfavourable when the children had suffered from severe birth asphyxia and in infants ventilated for prolonged recurrent apnoeic spells. The relation between the clinical indications for ventilator therapy and later outcome is obscured however, by a vast number of complicating perinatal events.