SummaryAlarms are key components of peri-operative monitoring devices, but a high false-alarm rate may lead to desensitisation and neglect. The objective of this study was to quantify the number of alarms and assess the value of these alarms during moderate-risk surgery. For this purpose, we analysed documentation of anaesthesia workstations during 38 surgical procedures. Alarms were classified on technical validity and clinical relevance. The median (IQR [range]) alarm density per procedure was 20.8 (14.5-34.2 [3.7-85.6]) alarms.h À1 (1 alarm every 2.9 min) and increased during induction and emergence of anaesthesia, with up to one alarm per 0.99 min during these periods (p < 0.001). Sixty-four per cent of all alarms were clinically irrelevant, whereas 5% of all alarms required immediate intervention. The positive predictive value of an alarm during induction and emergence was 20% (95% CI 16-24%) and 11% (95% CI 8-14%), respectively. This study shows that peri-operative alarms are frequently irrelevant, with a low predictive value for an emerging event requiring clinical intervention.

The results of fluoroscopy-guided PCC are satisfactory with case series reporting complete pain reduction in as much as 82-95% of the patients. For CT-guided PCC initial success rates were reported between 80.5-92.5% patients. However, the complication rates and long-term effects if measured and/or mentioned, varied. Hypothetically this technique may be more accurate and therefore probably safer than fluoroscopic-guided PCC.

Preconditioning, but not postconditioning, with Sevoflurane reduces pulmonary neutrophil accumulation after ischaemia/reperfusion injury of the lower body. Since neutrophil accumulation plays a major role in the pathophysiology of acute lung injury, our data suggest a protective effect of Sevoflurane preconditioning on remote pulmonary ischaemia/reperfusion injury.

Quantitative information about the effects of pulmonary blood volume (Qp) on pulmonary haemodynamics is lacking since Qp changes inevitably with flow. To separate flow-dependent from volume-dependent changes in intravascular pressures we imposed changes in Qp (measured continuously) by altering outflow pressure in seven isolated, blood-perfused rabbit lungs and studied the effects of Qp on the relations between arteriovenous pressure gradient (DeltaP) and blood flow (Q.) under two conditions: flow-dependent volume changes were either permitted or compensated. In the latter circumstances, DeltaP changed more for a given change in Q.. The DeltaP/Q. relations were shifted to smaller DeltaP when Qp was increased. Hence, the calculated flow resistance (R = DeltaP/Q.) decreased with increasing Qp at a given Q.. Assuming constant viscosity, changes in R can be predicted from changes in vessel geometry and thus Qp. We found that R increased less than expected (by a factor of 3-7.5 instead of 9) when Qp was reduced to one-third. This discrepancy may be explained by a change in blood distribution within the lung despite constant Qp and by a change in apparent blood viscosity with Q.. Regardless of these speculations we have shown that Qp determines DeltaP at each flow and thus flow resistance.

No abstract