Users' opinions on intensive care unit alarms--a survey of German intensive care units.

Monitoring of physiologic parameters in critically ill patients is associated with an enormous number of alarms, leading to reduced clinical value with high sensitivity but low specificity. To evaluate opinions of intensive care unit (ICU) staff on current monitoring we conducted a survey of German ICUs. Furthermore, the survey aimed to assess requirements and requests for future alarm systems. The survey was conducted between May 2006 and June 2007 on a randomised sample of German ICUs. Questionnaires with 24 partly closed-ended partly open-ended questions were posted. Of 915 letters, 274 (30%) from 185 contacted ICUs were returned and evaluated. One hundred and sixty physicians, the majority (52%) working in a department of anaesthesiology, and 114 nurses returned the survey. Most responders (87%) estimated that less than 50% of current alarms result in clinical consequences (52% estimated less than 25%). We suggested trend alarms, smoothing of signals to reduce artefacts, generation of new combined alarms and integrative monitoring of different alarm systems as improvements of current ICU alarm systems, all of which were agreed to by the majority. Free text commentaries focused on the need for reducing alarms caused by artefacts and called for improvement of the monitor-user interfaces. Our survey demonstrates the dissatisfaction of clinical staff with the current alarm systems regarding alarm frequency and specificity in German ICUs, thereby confirming data raised in single institutions. ICU staff's acceptance for new alarm algorithms like signal extraction or detection of trends as a basis for smart monitoring appealed to the majority of users.

The creation of linear contiguous lesions in the atria with an expandable loop catheter.

OBJECTIVES: This article describes a catheter system designed to create linear atrial lesions and identifies electrophysiologic markers that are associated with the creation of linear lesions. BACKGROUND: Atrial fibrillation (Afib) is the most common arrhythmia in humans and causes a significant morbidity. The success of surgical interventions has provided the impetus for the development of a catheter-based approach for the ablation of Afib. METHODS: We tested a catheter system with 24 4-mm ring electrodes that can create loops in the atria. The electrodes can be used to record electrical activity and deliver radiofrequency power for ablation. In 33 dogs, 82 linear lesions were generated using three power titration protocols: fixed levels, manual titration guided by local electrogram activity and temperature control. Bipolar activity was recorded from the 24 electrodes before, during and after lesion generation. Data were gathered regarding lesion contiguity, transmurality and dimensions; the changes in local electrical activity amplitude; the incidence rate of rapid impedance rises and desiccation or char formation; and rhythm outcomes. RESULTS: Catheter deployment usually requires <60 s. Linear lesions (12 to 16 cm in length and 6 +/- 2 mm wide) can be generated in 24 to 48 min without moving the catheter. Effective lesion formation can be predicted by a decrease of greater than 50% in the amplitude of bipolar recordings. Splitting or fragmentation of the electrogram and increasing pacing threshold (3.1 +/- 3.3 mV to 7.1 +/- 3.8 mV, p < 0.01) are indicative of effective lesion formation. Impedance rises and char formation occurred at 91 +/- 12 degrees C. Linear lesion creation does not result in the initiation of Afib. However, atrial flutter was recorded after the completion of the final lesion in 3/12 hearts. When using temperature control, no char was noted in the left atrium, whereas 8% of the right atrium burns had char. CONCLUSIONS: This adjustable loop catheter forces the atrial tissue to conform around the catheter and is capable of producing linear, contiguous lesions up to 16 cm long with minimal effort and radiation exposure. Pacing thresholds and electrogram amplitude and character are markers of effective lesion formation. Although Afib could not be induced after lesion set completion, sustained atrial flutter could be induced in 25% of the hearts.