Highly conservative phlebotomy in adult intensive care--a prospective randomized controlled trial

Anaemia in critically ill patients is common and phlebotomy associated blood loss may contribute towards this anaemia. The aims of this study were twofold. Firstly, a survey was conducted to provide a summary of current phlebotomy practices within Australian intensive care units. A standardized telephone survey was aimed at Australian intensive care units registered with Australia and New Zealand Intensive Care Society (ANZICS) and questions regarding phlebotomy procedures directed at nursing staff. Secondly, a prospective randomized controlled trial aimed to assess the impact of a highly conservative phlebotomy procedure on haemoglobin concentration in intensive care patients. Patients admitted to our own intensive care unit were randomized using a sealed envelope technique to either a highly conservative phlebotomy group, or standardized controls. Blood was taken according to strict protocols and recorded along with haemoglobin concentration daily. The survey demonstrated that 16% of Australian units return deadspace volumes from in-line arterial sets and no unit routinely used paediatric-sized blood collection tubes. Using our highly conservative protocol, median phlebotomy-associated blood loss was reduced by over 80% (40 ml vs 8 ml P<0.001). Mean haemoglobin fell from 13.7 g/dl to 11.7 g/dl in controls (P=0.002) and from 12.7 g/dl to 11.5 g/dl (P=0.074) in our study group. We conclude that highly conservative phlebotomy is feasible in a critical care unit and is associated with a reduction in blood loss.

Acute asthma and the life threatening episode

OBJECTIVE

To present a clinical approach to the management of acute asthma and the life threatening episode of asthma.

DATA SOURCES

A review of published peer-review articles and studies reported from 1966 to 1999 and identified through a MEDLINE search on the management of acute asthma, status asthmaticus and acute fulminant asthma.

SUMMARY OF REVIEW

Asthma is a disease caused by a chronic desquamative eosinophilic bronchitis with airway hyper-responsiveness to specific and non-specific stimuli. It is characterised clinically by episodic airflow obstruction. A life threatening episode indicates the presence of one of the three clinical types; acute severe asthma (an acute episode of bronchospasm where the FEV(1) is 30% or less than the predicted value), status asthmaticus (where the episode becomes resistant to beta-adrenergic agonists and corticosteroids), or acute fulminant asthma (where the onset is rapid and severe and the patient is obtunded). Management of acute severe asthma includes oxygen, continuous nebulised salbutamol (until an adequate clinical response occurs) and intravenous hydrocortisone (200 mg/70 kg i.v. followed by 50 mg/70 kg hourly or 200 mg 4-hourly). The patient's speech, conscious state, pulse and respiratory rate, peak expiratory flow rate, oximetry and blood gases should be monitored, and if there is no improvement or the patient deteriorates, admission to an intensive care unit is required. Additional therapy includes intravenous aminophylline (2mg/kg, followed by 4 mg/kg over 30 minutes), nebulised ipratropium (500 microg 6-hourly), high dose inhaled corticosteroids, intravenous magnesium sulphate (5-10 mmol as a bolus with 40 mmol over 1-2 hours), and even inhaled helium oxygen mixtures. With further deterioration or for the management of acute fulminant asthma, intravenous adrenaline (20-200microg bolus followed by an infusion of 1-10 microg/min) is often used. Endotracheal intubation, with mechanical ventilation (using low tidal volumes and low respiratory rates) ketamine anaesthesia (1-2 mg/kg followed by 50 microg/kg/min), inhaled anaesthetic agents (e.g. diethyl ether) and even extracoporeal life support (using extracorporeal membrane oxygenation) may be required.

CONCLUSIONS

Inhaled salbutamol and intravenous corticosteroids are initially administered to manage the episode of acute severe asthma. Management of acute fulminant asthma or status asthmaticus requires admission to the intensive care unit and may require anaesthetic agents and complex life support techniques.

Cerebral salt wasting syndrome: a case report

A case of hyponatraemia associated with subarachnoid haemorrhage is presented. The provisional diagnosis of an inappropriate antidiuresis was made and treatment with fluid restriction was instituted. However the patient continued to deteriorate as the diuresis continued and the hyponatraemia worsened, resulting in hypovolaema. The salt wasting syndrome was subsequently diagnosed and saline and fludrocortisone (0.2 mg/day) was initiated, reducing the renal salt loss, increasing the plasma sodium and improving the neurological status of the patient. Cerebral salt wasting syndrome is an important and under-recognised cause of hyponatraemia in neurosurgical patients, particularly in patients with subarachnoid hemorrhage. It is essential to differentiate it from the syndrome of inappropriate antidiuretic hormone secretion to avoid complications of hypovolaemia and reduced cerebral perfusion as illustrated by this case. Brain natriuretic peptide may be responsible for this syndrome although this requires further investigation.

The effect of different bypass flow rates and low-dose dopamine on gut mucosal perfusion and outcome in cardiac surgical patients

The aim of this double-blind, randomized, placebo-controlled trial was to investigate the effects of different cardiopulmonary bypass flow rates and low-dose dopamine on gastric mucosal pH (pHi) and outcome. We hypothesized that by minimizing gut mucosal hypoperfusion during and after cardiac surgery endotoxin translocation may be prevented, resulting in an improved clinical outcome. Four groups of 25 patients each receiving high or low flows during bypass and low-dose dopamine or saline for 24 hours after induction of anaesthesia were studied. The pHi was measured at six time intervals over 24 hours. The combination of low-dose dopamine and a low bypass flow rate was associated with a significantly greater frequency and severity of low pHi. This group also demonstrated a significantly lower vascular resistance on admission to the intensive care unit. There may be an association between low pHi and low vascular resistance.