Early and late parameters describing the offset of neuromuscular blockade are highly intercorrelated.

BACKGROUND: Neuromuscular blocking agents have always shown wide inter-individual variability when it comes to their duration of action. This prevents clinicians from anticipating the evolution of the neuromuscular block for any given patient. With this study, we aimed to assess the nature of the relationships existing between different time course parameters used to describe paralysis onset and offset. METHODS: Sixty American Society of Anesthesiologists (ASA) score III-IV anaesthetised patients were randomised to receive a single equipotent dose (2ED95) of either rocuronium, mivacurium or atracurium. We used acceleromyography to monitor neuromuscular transmission. We described the relationships between the time-interval measurements of: onset, the first response (T1) reappearance, T1 25% of control, train-of-four ratio 0.25 and 0.75. Pearson correlation coefficients were calculated. RESULTS: We found no significant relationships between onset and any of the four parameters used to describe the offset. On the other hand, we showed strong and highly significant linear relationships between all the parameters describing the offset for each of the muscle relaxants studied (correlation coefficients ranging from 0.850 to 0.992). CONCLUSIONS: We evidenced strong linear correlations between the four offset time course parameters of spontaneous recovery after a single neuromuscular blocking agents (NMBAs) bolus. Such relationships open up new clinical perspectives concerning quantitative neuromuscular transmission monitoring: the scope of individual valuable anticipation of the patient's recovery.

Physico-chemical and hygienic property modifications of stainless steel surfaces induced by conditioning with food and detergent.

The effect of repeated conditioning procedures (25 runs), consisting of soiling (milk and meat products) and cleaning steps, on the hygienic status, physico-chemical properties and surface chemical composition of stainless steel (SS) surfaces, was investigated. Five SSs differing in grade and finish were used. Both soiling and surface cleaning/conditioning procedures resulted in a similar increase in the surface contamination with carbon, while the changes in the basic component of the surface free energy depended on the conditioning procedure. The passive film was also affected, the Fe/Cr ratio in particular. The hygienic status was also changed, especially with milk as shown by monitoring the number of residual adhering Bacillus cereus spores after contaminating the surface with spores followed by cleaning. The results show that in food environments, the presence and the nature of conditioning molecules play a major role in the hygienic status of SS surfaces.

Influence of surface chemistry on the hygienic status of industrial stainless steel.

Coupons of fourteen different stainless steels were investigated in terms of surface chemistry and ease of cleaning. Steel surfaces were exposed to Bacillus cereus spores in static saline solution for 2 h. Surfaces were rinsed and then covered with whole milk and allowed to dry. Surfaces were then cleaned in an experimental flow system that mimics an industrial application. After cleaning, remaining spores were released by sonication, spores cultured and colony forming units determined. Surfaces with higher levels of Fe in the outer surface of the passive film cleaned more easily. There was a relation between the polar component and ease of cleaning. The higher the polar component the more easily the surface cleaned. The cleaning mechanism involves dissolution of Fe enriched hydroxide films on the surface.

Effects of acute decrease in systemic afterload on accuracy of Doppler-derived left ventricular rate of pressure rise measurement in anesthetized patients.

OBJECTIVES: This study was designed to describe exactly the effects of acute decrease in systemic afterload on the accuracy of Doppler-derived left ventricular rate of pressure rise (LV DeltaP/Delta(t)) measurements compared with other routinely used indices of systolic function. METHODS: Twelve patients scheduled for coronary artery bypass grafting were studied. After induction of anesthesia (T0), afterload was modified by incremental administrations of nicardipine (T1-4). At each step of the procedure, thermodilution-derived cardiac index, left ventricular (LV) fractional area change, and LV DeltaP/Delta(t) were measured, and systemic vascular resistances were calculated. RESULTS: During the procedure, the systemic vascular resistances decrease averaged 13.4%. Systemic vascular resistances were correlated with LV DeltaP/Delta(t) (r = 0.843, P =.003) but inversely correlated with cardiac index (r = -0.782, P =.005) and LV fractional area change (r = -0.887, P =.003). CONCLUSION: In conclusion, and inversely to cardiac index or LV fractional area change, LV DeltaP/Delta(t) does not overestimate LV contractility in the presence of an acute decrease in systemic afterload.

Anaesthetic management of a child with type VIIc Ehlers-Danlos syndrome.

Ehlers-Danlos syndrome type VIIc is characterized by altered tensile strength of connective tissue. Several severe complications exist but skin fragility is the origin of perioperative morbidity during routine procedures. We describe the difficulties encountered during the anaesthetic management of a child suffering from the disease, and suggest special care advices to avoid any skin injury.

Bronchodilating and density dependence effects of fenoterol, ipratropium bromide and Duovent in reversible chronic obstructive pulmonary disease.

The bronchodilating effect of Duovent (0.2 mg fenoterol +0.8 mg ipratropium bromide) was compared with that of each of its components at the same doses. Twenty patients were included in the trial. Maximum expiratory flow-volume curves with air and helium-oxygen, intrathoracic gas volume and airway conductance were used for assessing the bronchomotor tone before and 15, 30, 60, 240 and 360 min after drug administration. All the drugs showed a significant bronchodilating effect. No differences between Duovent and fenoterol or ipratropium bromide were observed except a slight but statistically significant greater decrease of ITGV with Duovent. When expressing the data as percentage variation of the initial values, Duovent induced a better effect than the other drugs. The evaluation of density dependence was highly disappointing, and no conclusion can be drawn.