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Biomedical subjects

P V van Heerden

Publications and source records attributed to P V van Heerden.

At least 19 recordsLinked to original sources
PubMed2005

Clinical evaluation of USCOM ultrasonic cardiac output monitor in cardiac surgical patients in intensive care unit.

BACKGROUND: The USCOM ultrasonic cardiac output monitor (USCOM Pty Ltd, Coffs Harbour, NSW, Australia) is a non-invasive device that determines cardiac output by continuous-wave Doppler ultrasound. The aim of this study was to evaluate the accuracy of the USCOM device compared with the thermodilution technique in intensive care patients who had just undergone cardiac surgery. METHODS: We conducted a prospective study in the 18-bed intensive care unit of a 600-bed tertiary referral hospital. Twenty-four mechanically ventilated patients were studied immediately following cardiac surgery. We evaluated the USCOM monitor by comparing its output with paired measurements obtained by the standard thermodilution technique using a pulmonary artery catheter. RESULTS: Forty paired measurements were obtained in 22 patients. We were unable to obtain an acceptable signal in the remaining two patients. Comparison of the two techniques showed a bias of 0.18 and limits of agreement of -1.43 to 1.78. The agreement may not be as good between techniques at higher cardiac output values. CONCLUSIONS: The USCOM monitor has a place in intensive care monitoring. It is accurate, rapid, safe, well-tolerated, non-invasive and cost-effective. The learning curve for skill acquisition is very short. However, during the learning phase the USCOM monitor measurements are rather 'operator dependent'. Its suitability for use in high and low cardiac output states requires further validation.

Adult↗
PubMed2005

Non-invasive Mechanical Ventilation Enhances Patient Autonomy in Decision-Making Regarding Chronic Ventilation.

OBJECTIVE: Patients with respiratory failure due to progressive muscle weakness often require chronic ventilatory support, but many do not make decisions regarding ventilation prior to a crisis. We studied the use of non-invasive ventilation as a tool to enable communication and facilitate decision-making regarding chronic ventilation. METHODS: Patients with profound muscle weakness and acute respiratory failure, were supported or weaned by non-invasive positive or negative pressure ventilation. The patients were then interviewed and their informed autonomous decisions were used to plan their future management. RESULTS: Non-invasive ventilation could be used safely to support patients with acute respiratory failure until decisions regarding chronic ventilation are made and as an alternative means of ventilation for those who refuse tracheostomy. CONCLUSIONS: Non-invasive ventilation may be used in patients with profound muscle weakness, as a means of enhancing patient autonomy by improving communication and maintaining ventilation until decisions about ongoing care are made.

Journal Article↗
PubMed2004

Air embolism--a case series and review.

Venous or arterial air embolism may be a life threatening event. The condition is seen in many fields of medicine, including intensive care. We present a series of three cases of air embolism encountered in the intensive care unit, which demonstrate different pathophysiologies for air embolism in critically ill patients. We also review the literature with respect to aetiology, incidence, pathophysiology, diagnosis and treatment options for venous and arterial embolism.

Journal Article↗
PubMed2004

Percutaneous tracheostomy--long-term outlook, a review.

OBJECTIVE: To review the techniques and long term complications of the various techniques of percutaneous tracheostomy in the critically ill patient. DATA SOURCES: A review of studies reported on the various percutaneous tracheostomy techniques. SUMMARY OF REVIEW: A tracheostomy is frequently performed in the critically ill patient when prolonged mechanical ventilation, airway protection and pulmonary toilet are required. It is also facilitates weaning from mechanical ventilation, reduces laryngeal injury and improves patient comfort thus decreasing the need for sedation. The percutaneous dilatational technique can be easily and rapidly performed at the bedside. Short-term complication rates associated with percutaneous tracheostomies range between 7-22% and include bleeding, pneumothorax, subcutaneous emphysema, paratracheal insertion, posterior tracheal wall laceration, damage to or insertion through the endotracheal tube, hypoxia, hypotension and arrhythmias, cuff leak, endotracheal tube obstruction, loss of airway, premature extubation and wound infection. Peri-operative mortality ranges from 0.2 to 0.7%. The incidence of these complications often depends on the experience of the operator. Long-term complications and their incidence are not as well defined. CONCLUSIONS: In the critically ill patient who requires a tracheostomy, the percutaneous tracheostomy has become the method of choice as it can be performed at the bedside, leaves a smaller scar after decannulation and may be associated with fewer complications compared with the standard surgical technique.

Journal Article↗
PubMed2003

Long-term outcomes following percutaneous tracheostomy using the Griggs technique.

Percutaneous tracheostomy is commonly performed in the intensive care unit. This study assesses the long-term outcomes following percutaneous tracheostomy using the Griggs technique. We carried out a prospective observational cohort study. Two hundred and eight patients who had undergone percutaneous tracheostomy between 1 September 1996 and 31 July 2000 and who were alive at least six months following the procedure, were included in the study. Median follow-up was at 30 months. All patients were sent questionnaires regarding relevant symptoms. One hundred and six (51%) responded and were invited for further follow-up. Forty-three (20.6%) patients underwent scar evaluation by the investigators and 41/208 (19.7%) underwent spirometry. Of the responders, 38% complained of some degree of voice change and 12% complained of ongoing severe cough. Thirty-one per cent complained of shortness of breath, with more than half of these having concomitant heart or lung disease, which may explain this. Eighty-one per cent of patients had minimally visible or a visible but neat scar. Eight patients (8/41 (19.5%)) had some evidence of upper airway obstruction on spirometry, but only 2/41 (5% of patients) were symptomatic (stridor or shortness of breath). We conclude that percutaneous tracheostomy using the Griggs technique has an acceptable long-term complication rate.

Adolescent↗
PubMed2003

Clinical evaluation of the HemoSonic monitor in cardiac surgical patients in the ICU.

The HemoSonic monitor (HemoSonic 100, Arrow International, Reading, PA, U.S.A.) is a minimally invasive device to determine cardiac output by means of M-mode and pulsed Doppler ultrasound. We evaluated the HemoSonic monitor by comparing its output to paired measurements obtained by the standard thermodilution technique in patients who had recently undergone cardiac surgery. Forty-seven paired measurements were carried out in 13 patients. The correlation between the two methods was very good with a correlation coefficient of 0.81. Comparison of the two techniques using the method described by Bland and Altman showed a mean of the differences of -0.23. The limits of agreement were -2.35 to 1.89. There was a reduced correlation between techniques at higher values of cardiac output. We concluded that the HemoSonic monitor has a place in intensive care monitoring, with good correlation with cardiac output measured by the thermodilution technique. It appears to be less suitable for use in patients with a high cardiac output state. The oesophageal probe is moderately difficult for patients to tolerate and is only appropriate for use in sedated patients. The accuracy of the device is somewhat operator-dependent.

Cardiac Output↗
PubMed2002

Elective awake intubation in a patient with massive multinodular goitre presenting for radioiodine treatment.

We present the management of the potential airway complications in a case of massive multinodular goitre treated with radioactive iodine. The patient's trachea was prophylactically intubated, using a fibreoptic technique, to prevent further airway compromise due to thyroid oedema following radioactive iodine treatment. He remained awake and intubated for five days and was extubated when there was no clinical evidence of thyroid oedema as a consequence of his treatment. This approach avoided the considerable risk of thyroidectomy in a morbidly obese patient with airway obstruction. To the authors' knowledge this approach has not been previously described.

Airway Obstruction↗
PubMed2002

Closed-loop control of blood glucose levels in critically ill patients.

A closed-loop control system was constructed for automatic intravenous infusion of insulin to control blood sugar levels (BSL) in critically ill patients. We describe the development of the system. A total of nine subjects were recruited to clinically test the control system. In the patients who underwent closed-loop control of BSL, the controller managed to control only one patient's glycaemia without any manual intervention. The average BSL attained during closed-loop control approached the target range of 6-10 mmol/l, and had less deviation than when BSL had been maintained manually. We conclude that closed-loop BSL control using a sliding scale algorithm is feasible. The main deficiency in the current system is unreliability of the subcutaneous glucose sensor when used in this setting. This deficiency mandates high vigilance during use of the system as it is being developed.

Australia↗
PubMed2002

The effects of inhalation of a novel nitric oxide donor, DETA/NO, in a patient with severe hypoxaemia due to acute respiratory distress syndrome.

Aerosolized NONOates have been investigated in animal models in acute pulmonary hypertension, but none have been used in humans. We report the first use of aerosolized diethylenetriamine nitric oxide adduct (DETA/NO), a NONOate, in a patient with severe acute respiratory distress syndrome. Both pulmonary vascular resistance index and mean pulmonary arterial pressure were reduced by a mean of 26% and 18% respectively after the administration of a single dose of DETA/NO (150 micromol). Intrapulmonary shunting also improved. There were no significant changes in systemic arterial pressure or arterial methaemoglobin concentration after DETA/NO inhalation. We conclude that DETA/NO aerosol produced selective pulmonary vasodilation, with an improvement in pulmonary haemodynamics and oxygenation, while having no measurable effect on the systemic circulation.

Administration, Inhalation↗
PubMed2001

Adult-to-adult living donor liver transplantation for fulminant hepatic failure.

The outcome of fulminant hepatic failure without timely liver transplantation is poor. We describe a 19-year-old woman with fulminant hepatic failure due to acute hepatitis B infection who received a living donor liver transplant from her sister. The donor's recovery was uneventful, allowing hospital discharge on Day 6. Two months after transplantation the recipient developed a biliary stricture requiring surgery. One year after transplantation, her liver function was normal.

Adult↗
PubMed2000

Pulmonary toxicity of inhaled aerosolized prostacyclin therapy--an observational study.

Large white/landrace piglets (mass 11 to 21 kg) were exposed to aerosolized alkaline glycine diluent (n = 2) or inhaled aerosolized prostacyclin (n = 2) for five to eight hours. Pigs receiving these aerosols developed mild acute sterile tracheitis, involving the superficial layers of the trachea, shown histologically and ultrastructurally. Pigs receiving the diluent aerosol also showed mild inflammatory changes in the bronchioles. These findings suggest caution with the use of high volumes of aerosolized alkaline glycine diluent during inhaled aerosolized prostacyclin therapy.

Administration, Inhalation↗