Does point-of-care ultrasonography cause discomfort in patients admitted with respiratory symptoms?

Design

The study was conducted as a questionnaire-based observational study with data collection
alongside two studies assessing the diagnostic accuracy and impact of POCUS in admitted
patients with respiratory symptoms 12], 18].

Setting, study population and ethics

The study took place at the medical section of the ED at Odense University Hospital,
Denmark. Corresponding to the inclusion periods of the simultaneously conducted diagnostic
accuracy studies two observational periods between November 2010 and May 2011 and
December 2011 to March 2013 were used 12], 18]. The ED has approximately 58,800 visits and 12,000 acute admissions each year, whereas
nearly 7700 (64 %) of the admissions are related the medical section of the ED. In
Denmark, all acute hospital admissions are in public hospitals and occur either as
a direct emergency admission or by referral from a general practitioner. Adult patients
admitted with respiratory complaints are all admitted to the medical ED, exceptions
being trauma patients and patients triaged directly to the department of cardiology
on a suspicion of heart disease. Hemodynamic stable patients suspected of having deep
vein thrombosis (DVT) or pulmonary embolism (PE), are seen in the department’s out-patient
clinic and not admitted to the ED.

The study was conducted according to the Helsinki Declaration and approved by the
Committee on Biomedical Research Ethics for The Region of Southern Denmark (ID S-2010074)
and the Danish Data Protection Agency (ID 2010-41-5142). Some of the enrolled patients
were part in a randomized clinical trial involving the use of POCUS (registered at
http://clinicaltrials.gov (NCT01486394)).

Participants

All patients admitted to the medical ED were following triage screened for study participation
by a study investigator. Patients were included if they fulfilled one or more of the
following findings:

Respiratory rate??20 breaths per minute

Oxygen saturation??95 %

Oxygen therapy initiated

Or if the patients answered yes to???1 of the following questions when screened:

Do you feel or have you felt any dyspnoea prior to the admission?

Do you experience or have you experienced coughing prior to the admission?

Do you experience or have you experienced chest pain prior to the admission?

Exclusion criteria

Permanent mental disability

Patient age??18 years

The sonographic examinations could not be performed within one hour after the primary
assessment

POCUS

As a part of the diagnostic accuracy studies POCUS of the heart, lungs and deep veins
was performed within one hour after the primary clinical assessment. All three types
of sonography were performed in all of the included patients. The sonographic examinations
were performed according to the following protocols:

Focus Assessed Transthoracic Echocardiography (FATE): Performed with a M4S or M5S phased array transducer (1.5 – 4.0 / 1.5-4.6 MHz) (General
Electric Company) using the FATE protocol 19].

Focused lung ultrasound (FLUS): Performed with an 8C or 3CRF micro convex transducer (3.5 – 11.5 / 2.0-4.2 MHz) or
a C1-5 curved abdominal transducer (2.0-5.0 MHz) (General Electric Company), using
a modification of the principles described by Lichtenstein and Volpicelli (Fig. 1) 20], 21].

Fig. 1. Examples of used transducer positions. a Transducer placed for subcostal view during FATE. b Transducer placed in an intercostal space at the anterior surface of the chest during
FLUS. c Transducer placed at the popliteal crease for assessment of the popliteal vein during
LCU

Limited compression ultrasonography (LCU): Performed with a 12 L or ML6-15 linear transducer (5.0 – 13.3 / 4.5-15 MHz) (General
Electric Company) according to the American College of Emergency Medicine’s imaging
criteria compendium 22].

The patients themselves choose the preferred position to assume while being examined
with sonography (e.g. sitting, supine). Examples of transducer positions for the three
different sonography protocols are shown in Fig. 1.

All the sonographic examinations were made by the same physician qualified in POCUS
(CBL) (FATE examinations??200, F-LUS examinations??400, LCU examinations??200).
A Logiq S8 or Vivid S6 (General Electric Company) ultrasound system was used for all
examinations.

The time used for the ultrasonographic examinations was defined as the time used from
when the transducer touched the patient’s skin for the first time to the examination
had been completed and stored on the ultrasound system. The feasibility of the ultrasonographic
examinations were assessed according to predefined criteria (see Additional file 1).

Assessment of patient-rated level of discomfort

To measure the patient-rated level of discomfort during POCUS a simple questionnaire
including 4 items was used. Three of the items were Likert items in which the patient
were asked to assess the level of discomfort experienced during FATE, FLUS and LCU
on a scale from one to ten. The score one corresponded to no discomfort and the score
ten corresponded to the worst level of discomfort imaginable by the patient. A score
of one to two was believed as being a low score; hence pragmatically it was chosen
that if the patient scored any item more than two, the patient was asked whether they
could explain the reason for the increased score.

Patient-rated discomfort was chosen in order to encompass a variety of different aspects
causing patient discomfort during the examination (e.g. patient position during the
examination, pressure being applied on the skin by the transducer, cooperation to
the examination while having to cope with respiratory distress).

The final questionnaire item concerned whether the patient would accept or decline
being examined by the use of POCUS if the patient once again had to be examined for
possible disease. The questionnaire was filled out either by self-completion or by
assistance from a study investigator to solely read up the questions. All questionnaires
were filled out immediately after the sonographic examination. The questionnaire was
solely developed for this study and was not based on any previously validated questionnaires.
The questionnaire can be found in its original form (Danish) and an English version
in the Additional file 1.

Statistical analysis

From the two observation periods data was joined as one cross-section and descriptive
statistics were performed including: demographic characteristics, medical history,
patient symptoms and vital signs measured at arrival. Time spent for the sonographic
examinations were calculated as a median with corresponding 25^th and 75^th interquartiles (IQR) and range. Feasibility of the sonographic examination was calculated
as a proportion with corresponding 95 % confidence interval (CI). Patient-rated levels
of discomfort during the three sonographic examinations were calculated as median
with corresponding 25^th and 75^th IQR and range. The number of patients rating the level of discomfort two or lower
and the number of patients who would accept being assessed by the use of POCUS if
they had to be examined for possible disease were calculated as proportions with corresponding
95 % CIs. Data analysis was conducted using Stata Release Version 11.0 (StataCorp,
College Station, TX, USA).