An evaluation of protocolised weaning on the duration of mechanical ventilation.

Using a before and after study design, we compared protocolised weaning from mechanical ventilation with usual non-protocolised practice in intensive care. Outcomes (duration of mechanical ventilation, duration of intubation, intensive care stay) and complications (re-intubations, tracheostomy, mortality) were compared between baseline (Phase I) and following implementation of protocolised weaning (Phase II). Over the same period, we collected data in a second (reference) unit to monitor practice changes over time. In the intervention unit, outcomes were longer in Phase II compared with Phase I (all p < 0.005). When adjusted for admission APACHE II score and diagnostic category, only intensive care stay remained significantly longer (p = 0.002). There were significantly more tracheostomies in Phase II (p = 0.004). The reference unit demonstrated no statistically significant differences in study outcomes or complications between Phases. Protocolised weaning did not reduce the duration of mechanical ventilation and was not associated with an increased rate of re-intubation or intensive care unit mortality.

Propofol and alfentanil total intravenous anaesthesia: a comparison of techniques for major thoracic surgery.

BACKGROUND: Previous work has highlighted the disadvantages of propofol as a sole agent for total intravenous anaesthesia (TIVA). This randomised study investigated three combinations of propofol and alfentanil as TIVA for major thoracic surgery. METHODS: In 73 patients undergoing elective thoracic surgery, anaesthesia was conducted either with sodium thiopentone induction and inhalational maintenance (incorporating isoflurane) or with TIVA using propofol with alfentanil (by infusion at one of two rates or in incremental doses). Vital signs and recovery characteristics were recorded. RESULTS: There were no significant differences in heart rate or blood pressure between groups during either induction or maintenance. Depth of anaesthesia was controlled satisfactorily in all groups. Recovery characteristics were similar between treatment groups, although there was a trend towards earlier orientation in the group which received the highest infusion rate of alfentanil. CONCLUSION: Continuous infusions of propofol and alfentanil provide safe and reliable TIVA for major thoracic surgery. TIVA was found to be a satisfactory technique in more elderly patients than previously described. The higher of the two alfentanil infusion rates may result in a better combination of propofol and alfentanil with respect to recovery times than the lower.

The gastric tonometer. A valuable monitor of splanchnic perfusion?

Minimally invasive assessment of the adequacy of perfusion of the gastrointestinal tract has become clinically feasible with the availability of the gastric tonometer. This modified nasogastric tube permits calculation of the pH of the gut mucosal cells; a low tissue pH may indicate tissue hypoxia due to regional hypoperfusion. Such regional hypoperfusion is often undetected by other monitors and, if it occurs intra-operatively, may result in a poor outcome following major surgery. In critical illness, the splanchnic area seems to be particularly vulnerable to hypoperfusion and such a regional oxygen deficit is implicated in the causation of organ dysfunction/failure. Recent studies have begun to define the circumstances in which splanchnic tissue acidosis develops and several therapies have been proposed to reverse the regional oxygen deficit. This review seeks to clarify whether or not the tonometer is a valuable addition to our current monitoring aids.

Low gastric intramucosal pH: incidence and significance in intensive care patients.

Monitoring of gastric intramucosal pH (pHi) is advocated in critical illness to detect tissue acidosis due to regional hypoperfusion. However, the number of patients who may benefit from such monitoring remains unclear and the relationship between low pHi and outcome requires further definition. Sixty consecutive patients with Acute Physiology and Chronic Health Evaluation (APACHE II) scores < 30 were studied throughout ICU stay to investigate the incidence of low pHi (< 7.32 for > or = 1 hour), its relationship to outcome, and temporally associated clinical events. pHi was measured 2 to 6 hours post-ICU admission and 8-hourly thereafter. Forty-four patients (73%) exhibited low pHi. Fourteen patients died in ICU with 13 deaths occurring in the low pHi group (P = 0.05). Length of ICU stay was greater in the low pHi group (P = 0.02). The development of low pHi was temporally associated with maximal sepsis score, weaning from assisted ventilation and commencement of enteral feeding.

Correction of splanchnic oxygen deficit in the intensive care unit: dopexamine and colloid versus placebo.

Correction of the splanchnic oxygen deficit indicated by low gastric intramucosal pH (pHi < 7.35) appears to reduce ICU mortality. Dopexamine hydrochloride is in clinical use for this purpose but its efficacy has not been fully investigated. We report the results of a prospective, randomized, placebo-controlled study with a crossover design to assess the efficacy of dopexamine in correcting low pHi. Twelve patients in whom pHi < 7.32 was detected during eight-hourly monitoring were randomized to receive either incremental dopexamine (4-6 micrograms/kg/min) with colloid or 5% dextrose for three hours prior to crossover. There was no difference in pHi between treatments despite cardiovascular effects during dopexamine infusion. There was, however, a time-related increase in pHi suggesting a beneficial effect of conventional therapy. Dopexamine hydrochloride at 4-6 micrograms/kg/min in conjunction with colloid is not a clinically useful therapy to correct the splanchnic oxygen deficit indicated by low pHi.