[Iatrogenic events: a significant cause of admission in intensive care units]

OBJECTIVE

Identification and analysis of iatrogenic events leading to admission in intensive care units.

STUDY DESIGN

Prospective observational monocentric study.

PATIENTS

Critically ill patients hospitalized in adult medical intensive care unit of a general hospital over a twelve-month period.

METHODS

We recorded for each patient the following characteristics: origin, demographic datas, cause of admission, medical background, severity, diagnosis, ICU length of stay and provided treatments. Two medical investigators identified the iatrogenic character of events and determined their potential preventability. Univariate statistical analysis was performed.

RESULTS

During the study period, 603 patients were admitted and 71 (12%) due to iatrogenic events. In comparison to patients hospitalized for other causes, these patients were older (66 years vs. 60, P 0.009) and often previously treated in a hospital (82% vs. 54%, P<0.0001). They had increased need for transfusions (39% vs. 26%, P 0.02) but less frequent indications for mechanical ventilation (67% vs. 77%, P 0.07). They had similar ICU mortality (20% vs. 19%). Among them, 27 iatrogenic events were considered as preventable.

CONCLUSIONS

Iatrogenic event is a significant cause of ICU admission, involved in 12% of all the hospitalizations in our unit. It has an impact on the patient's profile (significantly older) and their ICU stay (increased need for transfusion). More than a third of events could be preventable and potentially accessible to corrective actions.

Influence of preoperative cognitive status on propofol requirement to maintain hypnosis in the elderly

BACKGROUND

The loss of cholinergic neurones in the basal forebrain has been shown to correlate to the extent of cognitive dysfunction during ageing in humans and to the hypnotic potency of propofol in animal models. We examined how the preoperative cognitive status, as assessed by mini-mental state examination (MMSE), may interact with propofol consumption during anaesthesia in the elderly.

METHODS

In a prospective study, we recruited 41 patients (65-99 yr) undergoing surgery for hip fracture. Femoral nerve block was performed for analgesia. Target-controlled infusion of propofol (Schnider's model) was adjusted to the bispectral index within the range 40-60. Multiple linear regression analysis determined whether age, BMI, gender, duration of anaesthesia, and preoperative MMSE score affected the propofol consumption (general linear model, Systat 8.0).

RESULTS

BMI and MMSE score significantly affected the mean value of propofol consumption. A low MMSE score (below 19) was associated with an observed decrease in propofol requirement in patients >65 yr of age. No significant effect of age, gender, and duration of anaesthesia on the propofol consumption was observed.

CONCLUSIONS

Propofol requirement to maintain hypnosis during general anaesthesia appears to decrease with deterioration in the cognitive status in the elderly. We suggest that a cognitive dysfunction linked to a cerebral cholinergic dysfunction may influence the brain sensitivity for propofol in aged patients.

Vertical InAs nanowire wrap gate transistors with f(t) > 7 GHz and f(max) > 20 GHz

In this letter we report on high-frequency measurements on vertically standing III-V nanowire wrap-gate MOSFETs (metal-oxide-semiconductor field-effect transistors). The nanowire transistors are fabricated from InAs nanowires that are epitaxially grown on a semi-insulating InP substrate. All three terminals of the MOSFETs are defined by wrap around contacts. This makes it possible to perform high-frequency measurements on the vertical InAs MOSFETs. We present S-parameter measurements performed on a matrix consisting of 70 InAs nanowire MOSFETs, which have a gate length of about 100 nm. The highest unity current gain cutoff frequency, f(t), extracted from these measurements is 7.4 GHz and the maximum frequency of oscillation, f(max), is higher than 20 GHz. This demonstrates that this is a viable technique for fabricating high-frequency integrated circuits consisting of vertical nanowires.