Clinically relevant potential drug-drug interactions in intensive care patients: A large retrospective observational multicenter study

PURPOSE

Potential drug-drug interactions (pDDIs) may harm patients admitted to the Intensive Care Unit (ICU). Due to the patient's critical condition and continuous monitoring on the ICU, not all pDDIs are clinically relevant. Clinical decision support systems (CDSSs) warning for irrelevant pDDIs could result in alert fatigue and overlooking important signals. Therefore, our aim was to describe the frequency of clinically relevant pDDIs (crpDDIs) to enable tailoring of CDSSs to the ICU setting.

MATERIALS & METHODS

In this multicenter retrospective observational study, we used medication administration data to identify pDDIs in ICU admissions from 13 ICUs. Clinical relevance was based on a Delphi study in which intensivists and hospital pharmacists assessed the clinical relevance of pDDIs for the ICU setting.

RESULTS

The mean number of pDDIs per 1000 medication administrations was 70.1, dropping to 31.0 when considering only crpDDIs. Of 103,871 ICU patients, 38% was exposed to a crpDDI. The most frequently occurring crpDDIs involve QT-prolonging agents, digoxin, or NSAIDs.

CONCLUSIONS

Considering clinical relevance of pDDIs in the ICU setting is important, as only half of the detected pDDIs were crpDDIs. Therefore, tailoring CDSSs to the ICU may reduce alert fatigue and improve medication safety in ICU patients.

[Initiating patients on home mechanical ventilation]

More and more patients with chronic respiratory insufficiency are eligible for home mechanical ventilation. As a result, medical doctors are increasingly confronted with said patients. The treatment goal of this supporting therapy is to improve quality of life and possibly life extension. Centres for home mechanical ventilation decide on the indication, whereas the clinical setup of the ventilator takes place in a hospital setting. Staff in the Dutch Gelderse Vallei hospital have been initiating - both non-invasive and invasive - home mechanical ventilation for various patient groups for the last 4 years. This is a labour-intensive process during which numerous issues can occur. Experience and expertise is necessary for a successful process. A multidisciplinary approach and accessible consultation between stakeholders is of great importance when setting up home mechanical ventilation for these patients.

Influence of different supine body positions on blood pressure: consequences for night blood pressure/dipper-status

OBJECTIVES

To investigate the influence of different supine body positions on blood pressure measured by an ambulatory device.

DESIGN AND METHODS

Twenty hypertensive and 20 normotensive subjects of a tertiary hospital outpatient clinic participated. Blood pressure was measured with an ambulatory blood pressure device while lying in the back, left side, right side and abdominal positions. The distance between the antecubital fossa and sternum was measured in all four body positions. An expected blood pressure difference between the arm of measurement and the right atrium (i.e. the midsternum) was calculated for the different body positions.

RESULTS

When blood pressure was measured in side position at the left arm in hypertensive subjects, the mean systolic and diastolic blood pressure differences (+/- SD) between the left arm in the lower position and in back position at the same arm were +5/+4 (8/6) mmHg. These differences were -14/-17 (6/4) mmHg for the left arm lying above heart level in side position. Values of the right arm in hypertensives and the measurement at both arms in normotensive subjects yielded similar differences.

CONCLUSIONS

Body and arm position can both significantly influence the ambulatory blood pressure and therefore the day-night difference. This comprises one of the main reasons for the moderate individual reproducibility of the blood pressure fall at night.

Reproducibility of ambulatory blood pressure monitoring in daily practice

The reproducibility of ambulatory blood pressure monitoring (ABPM) was investigated in 45 untreated hypertensive patients in an out-patient clinic. Subjects with symptoms or diseases which could probably give rise to an increase in blood pressure (BP) variability were excluded. Patients underwent office BP (OBP) measurements and ABPM measurements with the Oxford Medilog device twice. The data were edited following previous set standards. Reproducibility of ABPM was good for the group: 24 h ABPM difference 0/2 mm Hg, standard deviation of the difference (SDD) 12/6 mm Hg for systolic BP and diastolic BP respectively. For OBP the difference between the two visits was 5/2 mm Hg with a SDD of 15/8 mm Hg. Intra-individual reproducibility was poor; almost half of the patients had a systolic difference of more than 10 mm Hg between both ABPM recordings. Reproduciblity of the day-night difference with a BP fall of at least 10% (dipper status) was moderate. About 60% of the subjects were dippers at one of the ABPM recordings but only 42% had a reproducible dip. Possible factors playing a role in the disappointing reproducibility of the ABPM recordings are the difference in daily activities between both recording days, decreased accuracy at higher BP, quality of sleep and the probable lower accuracy of the device during real ambulant conditions. In daily practice ABPM has no better reproducibility than OBP measurements, despite the larger number of measurements.

[Ambulatory blood pressure measurement]

Non-invasive ambulatory blood pressure monitoring (ABPM) is used as an additional diagnostic procedure particularly in specialist hypertension care. One application is diagnosing white coat hypertension. In general practice there is no established place for this diagnostic tool so far. At this time several studies are being carried out to investigate the prognostic value of ABPM. There are protocols of validation for ABPM monitors; nine of the 45 available up to now have been approved by the two most important test protocols. Reference values for normotension and hypertension are determined for the general population, but not for special groups of patients or for exercise conditions. One of the frequently mentioned advantages of ABPM over office blood pressure reading is the higher correlation of ABPM with hypertensive organ damage. To a large extent this superiority is based on the larger number of blood pressure readings. Repeated standardized office measurements reduce this advantage of ABPM.

Circulating adrenaline is not involved in the circadian blood pressure profile

BACKGROUND

Circadian changes in blood pressure are paralleled by analogous circadian changes in plasma catecholamines: blood pressure, plasma noradrenaline and adrenaline fall at night.

OBJECTIVE

To determine whether adrenaline is a prerequisite for the nocturnal fall in blood pressure, the circadian blood pressure profile was studied in adrenalectomized subjects, lacking circulating adrenaline.

SUBJECTS AND METHODS

Ten adrenalectomized subjects and 10 healthy age-matched normotensive controls underwent 24-h non-invasive ambulatory blood pressure monitoring with the Oxford Medilog device. Measurements were taken every 15 min from 7.00 a.m. until 11.59 p.m and every 30 min from 12 midnight until 6.59 a.m. The nocturnal blood pressure fall was calculated for each subject.

RESULTS

Mean +/- SD systolic blood pressure decreased at night by 13.2 +/- 9.5 mmHg in the adrenalectomized and by 11.7 +/- 7.3 mmHg (NS) in the control subjects. There was no significant difference between groups in the nocturnal diastolic blood pressure fall (14.4 +/- 5.1 and 13.1 +/- 5.2 mmHg, respectively). Systolic blood pressure decreased by > 10 mmHg in five of the adrenalectomized and eight of the control subjects. Diastolic blood pressure decreased by > 10 mmHg in eight of the adrenalectomized and eight of the control subjects.

CONCLUSION

The normal nocturnal fall in blood pressure in adrenalectomized subjects indicates that circulating adrenaline is not required for a normal circadian blood pressure rhythm.