Biomedical subjects
Z Kalenda
Publications and source records attributed to Z Kalenda.
Pulmonary perfusion in HFV: a potential hazard?
Capnograms recorded during HFV do not indicate ETCO2 but the washout difference (WOD). A method by which the ETCO2 can be accurately measured during HFV using a special device and a low flow sidestream capnograph is described. The importance of continuous, instantaneous ETCO2 monitoring is stressed. Capnograms recorded by this method were found to exhibit regular, periodical falls in WOD as soon as the heart rate (HR) approached the ventilator rate (VR) or its second or third harmonic. Simultaneous rises in PAP, RVP and CVP were noted. Using an oscillator model and two frequencies representing the HR and VR, innumerable patterns could be produced resulting from the interference of one frequency with the other. Different combinations of frequencies produced, when expressed in terms related to alveolar capillary flow, zero or near-zero zones which varied in duration from extremely prolonged to minimal or entirely absent. Analysis of the capnographic phenomena previously observed, by means of the patterns produced by the oscillator model, enabled such disturbances to be interpreted and avoided, clinically, by adjustment of the relative HR/VR. The advantages of capnographic monitoring in the prevention of such sequelae during HFV is emphasised.
Recent developments in ECT in Holland.
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[Anesthesia in dystrophia myotonica using the capnogram].
The dangers associated with anaesthesia and postoperative care in patients with dystrophia myotonica are reviewed. Weakness, atrophy and myotonia of the respiratory muscles and abnormal drug responses are among the many features of the disease which create specific problems. Capnography is obviously a monitor of particular value, yet capnograms in dystrophia myotonia patients have never been published. Abnormal capnograms recorded in a patient with dystrophia myotonica before and after the administration of neostigmine are described. A technique of anaesthetic management avoiding drug liable to produce abnormal reactions, and with the capnogram as a guide, is discussed.
Sitting or prone? Another argument for the latter.
The case is described of a one-year-old child who underwent a craniectomy in the prone position for the removal of an ependymoma of the cerebellar vermis which had invaded the fourth ventricle. Circulatory arrest occurred. External cardiac massage was successfully carried out without any change of position, and the operation was satisfactorily completed. It is suggested that such an outcome would have been less likely had the patient been in the sitting position. The value of capnography as a guide to the adequacy of the circulation is emphasized and illustrated.
Clinical and experimental experience with etomidate as a brain protective agent.
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Restoration of pulmonary perfusion by a serotonin antagonist.
R 41 468, a selective serotonin receptor blocking agent, was found to improve pulmonary perfusion in patients with venous air embolism, in patients with adult respiratory distress syndrome (ARDS), and in certain cases of impairment of the pulmonary circulation during prolonged major surgery accompanied by blood transfusion. Continuous monitoring of end-tidal (CO2 (FETCO2) by means of infra-red capnography combined with blood gas estimations were the principle methods of assessment used.
Monitoring as anesthesia draws to a close.
The closing phase of anesthesia is defined. Some of the hazards of this period are reported and illustrated by capnograms. It is claimed that the dangers arising at the end of anesthesia are insufficiently appreciated.
Periodic respiration. The capnographic interpretation.
Different type of periodic respiration are difficult to distinguish clinically although their identification may influence the diagnosis, prognosis and treatment. Often other forms of abnormal respiration are mistaken for periodic. Four capnograms are shown illustrating (1) true Cheyne-Stokes respiration, (2) irregular "pseudo-periodic" respiration a) after fentanyl, and b) in the presence of a brain tumour and (3) regular respiration interspersed with deep sighs which was diagnosed clinically as Cheyne-Stokes respiration. A plea is made for the routine use of capnography in order to provide a visual record of respiration.
The capnogram as a guide to the efficacy of cardiac massage.
Recordings from three patients in cardiac arrest are shown to illustrate the importance of monitoring pulmonary perfusion by means of the capnogram as a continuous guide to the cardiac output achieved by cardiac massage and resuscitation. Such monitoring allows the performance to be adjusted to obtain the maximal result.
Capnography during anesthesia and intensive care.
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[Significance of capnography in cases of pneumothorax occurring during artificial respiration].
The author reports the case of a premature new-born presenting a respiratory distress syndrome who was ventilated through a tracheal tube and in whom an artificial pneumothorax developed. Capnography quickly provided accurate data allowing an adaptation of therapy.
Etomidate as induction agent.
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The prevention of irreversible lung changes following reversible phrenic nerve paralysis.
Phrenic nerve paralysis frequently follows operations on the neck such as resection of a cervical or first rib. It all too often passes unrecognised or is incorrectly treated, leading to permanent lung damage which may be severe enough as to result in a functional pneumonectomy. This is particularly unfortunate since the phrenic nerve paralysis is usually temporary. Three case histories are described of reversible paralysis of the phrenic nerve in which, due to prompt diagnosis, the ensuing lung changes were either prevented or immediatley treated. Intermittent assisted respiration with a Monaghan respirator was used to provide nebulised inhalations of Mesna several times a day. The method is applicable via a tracheostomy, an endotracheal tube or a simple mouthpiece. The latter is illustrated. The therapy is not hindered by immobilisation of the head and neck and the level of consciousness of the patients is of no importance. Many chest X-rays demonstrate the rapid clearing of the lungs achieved. All three patients were discharged with perfectly normal lungs.
Anaesthesia with sulfentanil-analgesia in carotid and vertebral arteriography. A comparison with fentanyl.
The effects of the analgesics sulfentanil (R 30730) and fentanyl, on autonimic stability, cardiovascular stability, respiratory depression and post-operative behaviour were compared in a standardised anaesthetic technique. Twenty-nine patients undergoing neurological arteriographies, were treated with one or more doses of 0.5 mg fentanyl; 22 patients were treated with an initial dose of 0.05 mg of sulfentanil followed by repeat injections of 0.025 mg, when necessary. The analgesic potency of sulfentanil proved to be 12 times that of fentanyl while (in contrast to fentanyl), the duration of the respiratory depression after sulfentanil did not differ significantly from the duration of optimal analgesia. The effects of both drugs on blood pressure and heart rate were minimal; autonomic stability was excellent. No serious side effects were seen in any of the patients. After sulfentanil analgesia the patients were more rapidly awake and lucid, than after fentanyl-analgesia. Further investigations with this new and promising drug seem to be of great interest.
Capnography: a sensitive method of early detection of air embolism.
Seven capnograms are shown demonstrating the invariable fall in the level of expired CO2 which occurs during the operation for the insertion of a Pudenz-Heyer drain for hydrocephalus. The fall occurs when contrast medium is injected down the heart catheter after withdrawal of the guide but never after subsequent injections unless air is present in the syringe. The effect is shown not to be due to a difference in temperature between the contrast medium and the body. A comparison is made with a capnogram recorded during the setting up of an I.V. transfusion in an infant in which a small quantity of air was seen to enter the circulation along the tubing of the butterfly needle. It is concluded that the fall in the capnogram seen during Pudenz-Heyer operations is due to air embolism. The severity of its effect is shown to be proportional to the volume of air injected in relation to body weight. The value of the capnograph as a sensitive monitor of air embolism is emphasised together with the fact that the fall in the capnogram precedes that of the blood pressure or any other recordable effect.