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Anästhesie (Subject) / Krankheitsbilder (Lesson)
FMH
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- Persistierender Ductus botalli The physiological function of the ductus arteriosus in the fetus is to divert blood away from the lungs to the placenta. Constriction and functional closure occurs in the first 24 hours of life in response to increased environmental oxygen. In order to maintain life with some cardiac malformations, for example, pulmonary atresia, hypoplastic left ventricle and interrupted aortic arch, these patients require patency of the duct after birth. Indomethacin causes duct closure through an anti-prostaglandin effect. An infusion of alprostadil is used to maintain duct patency. Incidence of PDA is greater in preterm infants and birth at high altitude is associated with a greater risk.
- Respirationsversagen- Typ I und II In type I respiratory failure there is hypoxaemia accompanied by a normal or low arterial PCO2. Type II failure is hypoxaemia accompanied by an increased PCO2 (>6.5 kPa). Hypoxaemia can occur because of thre mechanisms: Hypoventilation Diffusion impairment VQ mismatch. Acute respiratory distress syndrome (ARDS) and hyaline membrane disease in addition to lung infections may cause both diffusion impairments and VQ mismatch. In the case of VQ mismatch and hypoventilation, the CO2 usually rises (type II respiratory failure). In these cases, the patient relies more and more on hypoxia to maintain respiratory drive, and an excess of oxygen can be counterproductive. Hypoxia is a potent pulmonary vasoconstrictor, and can lead to pulmonary hypertension and ventricular failure. Mountain sickness may cause type I respiratory failure because at high altitudes the PO2 is reduced, despite the oxygen content in the air remaining unchanged.
- Tricyklische Antidepressiva- Vergiftung Deaths from tricyclic antidepressant (TCA) overdose are usually due to arrhythmias and/or hypotension. Tricyclic antidepressant toxicity is due mainly to the quinidine-like actions of these drugs on cardiac tissues. Slowing of phase 0 depolarisation of the action potential results in slowing of conduction through the His-Purkinje system and myocardium. Slowed impulse conduction is responsible for QRS prolongation and atrioventricular block, and contributes to ventricular arrhythmias and hypotension. Other mechanisms contributing to arrhythmias include abnormal repolarisation, impaired automaticity, cholinergic blockade and inhibition of neuronal catecholamine uptake. Toxicity may be worsened by acidaemia, hypotension or hyperthermia. Sinus tachycardia is due to the anticholinergic effects of the tricyclic antidepressants as well as blockade of neuronal catecholamine reuptake. Sinus tachycardia is usually tolerated well and requires no therapy. Sinus tachycardia with QRS prolongation may be difficult to distinguish from ventricular tachycardia. Prolongation of the QRS duration >100 ms predicts a higher risk of arrhythmia and is an indication for systemic sodium bicarbonate administration. Serum alkalinisation favours dissociation of the tricyclic away from myocardial sodium channels, and the extracellular sodium load improves sodium channel function.
- Rauchen Smoking is a risk factor for significant intra-operative respiratory complications and post-operative respiratory, cardiovascular complications and wound infections. Nicotine and carbon monoxide are the main harmful substances in cigarette smoke. Smoking affects oxygen transport and delivery. It leads to narrowing of small airways, causing an increase in closing volume. The incidence of chronic obstructive airway disease is higher in smokers. When pulmonary function tests are done, chronic smokers show an obstructive pattern (with reduced forced expiratory volume and vital capacity) and the passive smokers show evidence of small airways disease as their closing volumes are significantly increased. The changes in closing volumes, forced expiratory volume, vital capacity and airway diameter are not the main cause of reduced oxygen delivery to the tissues. Reduced oxygen delivery to the tissues is primarily due to the carboxyhaemoglobin levels present in smokers, with levels of up to 15%. Carbon monoxide and oxygen both bind to the alpha chain of haemoglobin, but the affinity of carbon monoxide is 250 times greater than oxygen. The result of this is a reduction in the availability of oxygen binding sites and a reduction in oxygen carrying capacity. Left shift of the oxygen haemoglobin dissociation curve results in reduced oxygen delivery to the tissues. Carbon monoxide binds with cytochrome oxidase and myoglobin and inactivates mitochondrial enzymes in the cardiac muscle. There is a decrease in the intracellular oxygen transport and utilisation, and a negative inotropic effect leading to chronic tissue hypoxia. The half life of carboxy haemoglobin depends chiefly on pulmonary ventilation. At rest, the half life is about four to six hours. It has been found that the half life is longer in males than females. Administering 100% oxygen will significantly expedite the removal of carbon monoxide. With 100% oxygen, the half life of carbon monoxide is 40-80 minutes.
- Bronchopleurale Fistel Die bronchopleurale Fistel ist eine Verbindung zwischen Pleurahöhle und Bronchus. v.a. bei: Lungenabszess Bullae Zerreißung des Parenchyms durch zu hohen Druck währen einer Beatmung Nahtinsuffizienz nach Pneumektomie Karzinom bedingte Erosion Absolute Indikation für einen Doppellumentubus und eine Pleuradrainage vor Anästhesieeinleitung!
- Geriatric anaesthesia secrets of anaesthesia 441
- Allergie Allergic reactions may be triggered by acute complement activation (anaphylatoxins) and increased levels of histamine, bradykinins and leukotrines are common. The 5-lipoxygenase pathway produces leukotrienes. B cells are involved with humoral immunity due to antibody production form plasma cells. T cells are involved with cellular immunity but the T helper cells are involved in helping immature B cells mature. The gene linked with allergy is located on chromosome 6.
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