Halothane alters the oxygen consumption-oxygen delivery relationship compared with conscious state

The authors' objectives were as follows: 1) to characterize for the first time the relationship between whole body O2 delivery (DO2) and O2 consumption (VO2) in adult conscious dogs; and 2) to asses the effects of the inhalational anesthetic, halothane, on that relationship. DO2 was varied over a wide range in chronically instrumented dogs by gradual inflation and deflation of a hydraulic occluder implanted around the thoracic inferior vena cava to alter venous return and cardiac output. VO2 was measured at different values of DO2 in dogs in the fully conscious state and again during halothane anesthesia. A "binning" technique indicated that halothane decreased VO2 (P less than 0.01) at any given value of DO2 over a broad range of VO2. A two-line piecewise linear regression analysis technique indicated that halothane decreased (P less than 0.01) the critical O2 delivery (COD) from 20 +/- 3 to 10 +/- 1 ml.kg-1.min-1 and increased (P less than 0.01) O2 extraction at COD from 31 +/- 3 to 40 +/- 2%. However, the DO2-VO2 plots measured in both conscious and halothane-anesthetized dogs did not exhibit a discrete discontinuity but rather were closely fit (correlation coefficient = 0.98) by an exponential equation of the following form: O2 extraction = B1.(1 - exp (-DO2/B2))/DO2, where B1 is the delivery-independent estimate of VO2 and B2 is the "delivery constant," i.e., the DO2 associated with a VO2 equal to 63% of B1. Halothane decreased B1 (P less than 0.01) from 5.3 +/- 0.1 to 3.9 +/- 0.1 ml.kg-1.min-1 and decreased B2 (P less than 0.01) from 5.6 +/- 0.3 to 3.6 +/- 0.3 ml.kg-1.min-1 compared with that measured in conscious dogs. Thus, compared with the conscious state, halothane anesthesia alters the fundamental relationship between DO2 and VO2 and may have a beneficial effect on tissue oxygenation at low values of DO2.     

Effects of 6-hydroxydopamine on pre- and post-junctional 5-HT1-like receptor-mediated responses in dog saphenous vein

Summary To investigate whether 5-HT₁-like receptor-mediated inhibition of adenosine 3 : 5-cyclic monophosphate (cyclic AMP) accumulation occurs in nerves or smooth muscle of saphenous vein, infusions of 6-hydroxydopamine (6-OHDA) were administered to dogs with the aim of inducing sympathetic nerve damage. The effects of 6-OHDA on other 5-HT₁-like receptor-mediated responses at the pre- and post-junctional level were investigated for comparison by studying 5-hydroxytryptamine (5-HT)-induced inhibition of ³H-noradrenaline release and contraction of smooth muscle respectively.Disruption of nerve function by 6-OHDA was revealed by the lack of catecholaminergic fluorescence and neurogenic contractile responses in saphenous veins from dogs treated with 6-OHDA. In addition, severe impairment of neuronal uptake mechanisms were apparent since basal efflux of ³H-noradrenaline, electrically-evoked release of ³H-noradrenaline and remaining ³H-noradrenaline content were considerably reduced. Some ³H-noradrenaline was taken up and released in 6-OHDA treated tissues which is consistent with the existence of nerve varicosities resistant to the present dosing regime of 6-OHDA, an observation substantiated by electron microscopy studies showing inconsistent lesions of nerve terminals.6-OHDA pre-treatment potentiated the smooth muscle contractile responses mediated by 5-HT₁-like receptors as well as potentiating 5-HT-evoked inhibition of prostaglandin E₂-stimulated cyclic AMP accumulation. It did not, however, affect 5-HT-induced inhibition of ³H-noradrenaline release. The present results suggest that inhibition of cyclic AMP accumulation by 5-HT occurs predominantly in smooth muscle. Correspondence to A. J. Kaumann at the above address     

Histopathological features of congenital fundus lesions in familial adenomatous polyposis

We report the light and electron microscopic findings for two lesions from two patients who died of complications of familial adenomatous polyposis. In the first case microscopy of a small (100 to 200 mu), uniformly dark lesion (the commonest type seen in this condition) showed enlarged retinal pigment epithelial cells with an increased number of pigment granules. This is consistent with the term "hypertrophy of the retinal pigment epithelium", currently used to describe these lesions. In the second case we sectioned a larger (1000 to 1500 mu), oval, grey lesion from the posterior pole. The pigment epithelium was normal, but between it and outer retina was an unusual choristoma consisting largely of myelinated axons and astrocytes.     

Job satisfaction of nursing assistants in long-term care

A study of job satisfaction of nursing assistants (NAs) was conducted in two nursing homes (one in a relatively poor urban neighborhood, the other in an affluent suburban neighborhood). When it comes to job content, NAs were more satisfied than dissatisfied. However, they are less satisfied with working conditions. The NAs of the suburban facility were less satisfied than those of the urban facility. Managers need to focus more on the work environment than on job content to develop a more satisfied work force.     

Human endothelin-1 clearance kinetics revealed by a radiotracer technique

Levels of endothelin-1 (ET-1) are elevated in many disease states, although its total body kinetics of elimination are poorly understood. Therefore, it remains uncertain whether the presence of elevated levels of ET-1 in the setting of disease are secondary to changes in production or clearance or some combination thereof. Using a 125I-labeled ET-1 infusion technique, the volume of distribution and kinetics of clearance of endothelin were described in five normal volunteers. Heart rate, blood pressure, right atrial pressure, and arterial blood samples for the counting of 125I and the measurement of ET-1 were obtained at multiple time points before and up to 45 h after the start of the infusion. The radiotracer infusion had no effect on heart rate, blood pressure, right atrial pressure, or endogenous ET-1 levels. ET-1 clearance was best described by a three-compartment model, which revealed that ET-1 has a much longer terminal half-life and volume of distribution than was previously reported. This suggests extensive uptake of ET-1 in various organ systems and slow clearance. These new findings have important implications for the understanding of the pathophysiology of ET-1 in disease states as well as for the understanding and development of ET-1 receptor blockers and endothelin-converting enzyme inhibitors.     

Staff confidence in dealing with aggressive patients: a benchmarking exercise

Interacting with potentially aggressive patients is a common occurrence for nurses working in psychiatric intensive care units. Although the literature highlights the need to educate staff in the prevention and management of aggression, often little, or no, training is provided by employers. This article describes a benchmarking exercise conducted in psychiatric intensive care units at two Western Australian hospitals to assess staff confidence in coping with patient aggression. Results demonstrated that staff in the hospital where regular training was undertaken were significantly more confident in dealing with aggression. Following the completion of a safe physical restraint module at the other hospital staff reported a significant increase in their level of confidence that either matched or bettered the results of their benchmark colleagues.     

Paraganglioma of the Cauda Equina Region – Report of two Cases and Review of the Literature

Summary  A paraganglioma of cauda equina region is extremely rare and except for secreting tumour, the pre-operative diagnosis of paraganglioma is very difficult. Two cases of non-functional paragangliomas of the cauda equina region are reported, one was attached to the filum terminale and the other to a rootlet looking very much like a vascular neurinoma. Both were successfully removed by surgery. An extensive review of the literature permits one to find 77 other cases. The clinical, radiological, pathological (ultrastructural and immunohistochemical) features and surgical findings of all theses cases are discussed. Surgery remains the treatment of choice. No effect of radiotherapy on recurrence prevention has ever been demonstrated.     

Catastrophic familial rhabdomyolysis: compartment syndrome with muscle fiber regeneration

Two reports of patients with rhabdomyolysis are described. Patient 1 was a 4-year-old-girl who had a 48-hour history of pyrexia and a 24-hour history of vomiting, drowsiness, polydipsia oliguria, and back pain. She could not walk easily because of tenderness in the calves. She was treated with furosemide and dopamine. On day 9, she was mobilized with the aid of physiotherapy. After 2 years, she tired easily but could walk normally. Patient 2 was a 3-year-old girl who had a 24-hour history of general malaise, peripheral aches and pain, and increasing drowsiness. She had severe swelling in the calves. Full-leg four compartment fasciotomies were performed on both calves. After patient 2 healed, she was observed to have muscle regeneration, which is very rare.