European journal of intensive care medicine最新文献

The cardiovascular responses to tracheal suction were observed in 4 consecutive recently-injured tetraplegics with physiologically complete cervical spinal cord transections (C3-5) who were in spinal shock and needed artificial ventilation. In all 4 patients tracheal suction induced bradycardia and in 2 patients even cardiac arrest. The bradycardia occurred when the patients were hypoxic, and was prevented by the addition of oxygen to inspired air, or, if this was inadequate, by the administration of atropine. Two of the patients were agains studied several months later, after return of isolated spinal cord activity and spontaneous breathing. In both patients tracheal suction then caused tachycardia and increased respiratory effort. It is concluded that: 1. Tetraplegics with high cervical spinal cord transections who are in spinal shock and unable to breathe spontaneously are prone to bradycardia and cardiac arrest during tracheal suction. This is more likely to occur when they are hypoxic. 2. The bradycardia appears to be due to a vago-vagal reflex for both afferent and efferent limbs of the arc are in the vagus nerve. A number of factors play a part, including (I) absent sympathetic activity; (II) airway receptor stimulation; (III) hypoxia and (IV) the inability to breathe spontaneously (The pulmonary (inflation) vagal reflex which would normally oppose the cardio-inhibition caused by (II) and (III) is absent). 3. The bradycardia in response to tracheal suction can be prevented by adequate oxygenation, or if this cannot be achieved, by repeated atropine.

In 23 patients 18 to 73 years old transcutaneous PO2, relative local perfusion and cardiorespirogram during induction and end stage of anaesthesia were monitored. This method allows continuous sufficiently exact estimation of PaO2. The comparison between tcPO2 and corresponding blood gas analysis from arterial samples showed a good correlation of r=0.94. Thus continuous tcPO2 registration enables quick diagnosis of hypoxia and its therapy.

In six volunteers (5 male, 1 female) it has been shown that normal respiration made no statistical difference to the estimates of the mean stroke volume and the mean cardiac output as determined by the electrical impedance method of Kubicek et al, (1966). The coefficient of variation was usually increased by respiration. The use of those stroke volumes which occur only at end-expiration was not shown to yield a greater reproducibility with 3 other male volunteers. In the female subject it was found that the use of a digital averager triggered from the preceding R-wave of the ECG gave values for the mean stroke volume and cardiac output which were always lower than the conventional mean values obtained from a number of strokes. The expense of either of these approaches does not appear to be justified as a means of compensating for the effects of normal respiration on the impedance dZ/dt waveform.

Multivariate time series data in post-operative patients (respiratory and cardiovascular) are compared to reference groups. Using this technique under the program control of a computerized patient monitoring system (IBM 1800) various classes in the respiratory and cardiovascular spectrum can define the co-ordinate system in hyperspace. The patient in crisis is recognised by his deviation from normal rates of change of the variable set, as well as by the time trajectories of recovery in the hyperspace.

An index of myocardial blood flow developed from studies with a computer and a mechanical circulatory model has been investigated in 18 dogs. An intravenous injection of 131I is used with external scintillation detection over the left ventricle and the lung. The index is given by the ratio of the half time of the downslope of the curve recorded from the left ventricle to that of the curve recorded from the lung. This index has been compared with that suggested by Mena et al in which the left ventricular half time is compared with the half time of the brain curve. The effect on these indices and on the clearance of 133Xe of clamping the anterior descending branch of the left coronary artery has been observed. Statistically significant differences in both indices and in Xenon clearance were seen to be induced by coronary artery clamping but there was overlap between the clamped and unclamped values. The method used for coronary clamping also affected the results.

A specialized neurosurgical data acquisition and processing system was developed and applied in practice to monitor some 60 patients after head injury or neurosurgical operations. At first the system allowed off-line operation, and the experiences thus gained made it possible to implement the system in its present form for real-time on-line patient monitoring. The algorithms prepared in our laboratory allow rapid and concise presentation of results and have proved their usefulness in clinical practice. The main parameters of interest in neurosurgery are intracranial pressure (ICP) and the volume of cerebrospinal fluid (CSF) drained from one of the lateral ventricles. Examples of statistical analysis of both these variables, and their presentation in the form of tables, diagrams and histograms are given.

Twenty-nine patients with acute hypercalcemia secondary to carcinoma, myeloma and parathyroid adenoma have been treated with large doses of furosemide, mithramycin, or salmon calcitonin perfusion. With furosemide administration the treatment was successful in 6 of 10 patients. Furosemide was injected intravenously at the rate of 125 mg every 3 hours. With mithramycin perfusion only 2 of 8 patients have a return of the serum calcium levels to normal. With salmon thyrocalcitonin 3 of 10 patients obtained a good result. It can be interesting to suggest the association of furosemide and salmon calcitonin infusion to treat hypercalcemia of myeloma.

The temperature dependence of the resistivity of blood samples with haematocrits from 16 to 52.5% has been investigated over the temperature range of 22 degrees ot 40 degrees C at a frequency of 100 kHz. The resistivity of whole blood increased with an increase in haematocrit and a decrease in temperature. The data fitted the relationship: Pohm-cm=(6.272 Hct + 75.176) - (0.104 Hct + 1.467) tC weree Hct is the percentage haematocrit.

Computer and mechanical models of the circulation have been made to study isotopic techniques of determining indices of myocardial blood flow. Parameters in the program and dimensions in the mechanical model have been scaled to represent the human circulation. Single rapid injections of 131I labelled human serum albumen were given into the venous line of the mechanical model and records obtained from collimated scintillation detectors positioned over the heart, lung and brain. Similar injections and recordings were simulated in the computer model. Two indices of myocardial flow have been studied. The first, described by Mena et al. is the ratio of the half time of the downslope of the left ventricular curve to the half time of the downslope of the brain curve. This index distinguished myocardial flows of 0,5% and 10% of total cardiac output but was also affected by changes in cerebral flow. A new index is proposed in which the half time of the left ventricular curve downslope is related to the half time of the downslope of the lung curve. This index can distinguish myocardial flows of 0,5% and 10% total flow but is not affected by changes in cerebral flow.