Biomedical subjects
Publications and source records attributed to P V Van Heerden.
The pulmonary circulation and the mechanisms which generate pulmonary hypertension are reviewed. The role of these mechanisms in the common pulmonary hypertensive states are analysed, particularly those in acute lung injury. Management options are discussed, with particular emphasis on the use of selective pulmonary vasodilators.
Percutaneous dilational tracheostomy (PDT), first described in the 1950s, has become a common bedside technique in the Intensive Care Unit (ICU). This study compares the early complications associated with the use of the Ciaglia PDT (Cook Critical Care, Bloomington, USA) technique, with the newly available Portex PDT technique (Portex Ltd., UK). The Ciaglia technique was adopted in this ICU in July 1994 and twenty-nine patients had a tracheostomy using this set until January 1995. Complications during the procedure were collected prospectively. When the Portex PDT set became available in January 1995, it was decided to assess the complication rate of this technique and compare them to the previously-collected data using the Ciaglia PDT set. Twenty-five patients have had a tracheostomy using the Portex PDT set. There has been no mortality associated with either PDT set. Bleeding requiring intervention occurred in two patients in the Ciaglia group and three patients in the Portex Group. All these patients had a bleeding diathesis. Loss of airway control occurred on one occasion in the Ciaglia group due to premature removal of the endotracheal tube. The first routine tracheostomy tube change at day 7 was complicated in four cases in the Ciaglia group. One infected stoma was noted in the Ciaglia group at day 7. Both techniques result in rapid, safe placement of a tracheostomy tube in critically ill patients in the ICU, obviating the need for surgical referral and transport to the operating room.
Two case reports are presented where inhaled aerosolized prostacyclin (IAP) was used to good effect as a selective pulmonary vasodilator. It was used in the treatment of a patient with severe hypoxaemia secondary to amniotic fluid embolism and for hypoxaemia secondary to the acute respiratory distress syndrome (ARDS) in a patient with acute on chronic liver failure and intra-abdominal sepsis. An apparent dose-response curve is demonstrated in the second case. A dose of IAP of 30-40 ng/kg/min produced an effect on oxygenation in the patient with liver failure equal to that seen at the maximal dose of (50 ng/kg/min). Reduction in dose below 30 ng/kg/min resulted in a deterioration in oxygenation towards baseline/pre-treatment levels. Inhaled aerosolized prostacyclin is a potent pulmonary vasodilator with little or no systemic hypotensive effect. It is simple to administer and would appear to be a viable alternative to inhaled nitric oxide.
Nitric oxide 10 ppm and inhaled aerosolized prostacyclin 50 ng/kg/min were compared as selective pulmonary vasodilators in five patients with hypoxaemia secondary to acute respiratory distress syndrome. Neither agent resulted in systemic haemodynamic changes, indicating true pulmonary selectivity. Inhaled aerolized prostacyclin improved oxygenation to a degree comparable to nitric oxide, as measured by the arterial alveolar oxygen partial pressure gradient and shunt fraction.
The profound physiological disturbances associated with severe intracerebral pathology have long been recognized. These changes have also been described in the brain dead potential organ donor but have only been studied since the early 1980s. Physiological disturbances in the brain dead organ donor result in a diffuse vascular regulatory injury and a diffuse metabolic cellular injury. The net result of these changes is an inexorable deterioration of all organs and eventual "cardiovascular death" of the patient. This paper reviews these physiological changes and the effect they may have on solid transplantable tissues, and discusses the management of brain dead organ donor with regard to these changes. Current concepts of brain death and how they may affect the interpretation of the observed physiological changes are also reviewed.
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Postoperative hypoxaemia presents with varying degrees of severity. Aetiology of the condition is diverse and may originate in the pre-, intra- or postoperative periods. However, induction of anaesthesia and the type of operation are important initiating factors over which there is little control. The impact of postoperative hypoxaemia, especially when detected early, can be alleviated. This article attempts to explain the pathophysiology and provide suggestions as to detection and management of postoperative hypoxaemia.