Clinical feasibility and performance of a continuous finger blood pressure measurement device in the perioperative period

The department of Anesthesiology of the VUmc recently started to focus on
postoperative hemodynamic monitoring in surgical patients who have no arterial
entrance and are not ventilated. In order to do so, a continuous blood pressure
measurement device (Nexfin) should be validated in order to define its value in
this postoperative monitoring of patient hemodynamics. In the present study we
therefore aim to evaluate the clinical feasibility and performance of the
Nexfin device in the intraoperative and postoperative phase in healthy
volunteers and surgical patients.

* Is the model-derived cardiac output (CO) of the Nexfin comparable to the
thermodilution CO as measured by a pulmonary artery catheter (PAC) during
cardiac surgery? (OBJECTIVE I)
* Does the Nexfin reliably measure changes in stroke volume variation (SVV) and
pulse pressure variation (PPV) as induced by validated tests in healthy
volunteers? (OBJECTIVE II)
* Are SVV and PPV measurements of value in surgical patients when used for the
detection of perioperative and postoperative changes in system hemodynamics?
(OBJECTIVE III)

Open, prospective, observational trial
The study will be performed in the VU University Medical Center
Inclusion of healthy volunteers or patients undergoing cardiothoracic or
abdominal surgery

Nexfin device
Continuous blood pressure measurements will be performed by placing a finger
cuff around the middle index of the dominant hand. The hand will be placed in a
comfortable position when the patient or volunteer is in a supine position.
This technique is associated with minimal discomfort for the patient.
Perioperative measurements
Except for the blood pressure measurement in the 30 minutes before anesthesia
induction, all intraoperative Nexfin measurements will be performed under
anesthesia. All anesthesia and surgery procedures will be performed as usual.
Discomfort due to intraoperative Nexfin measurements is regarded as minimal.
Valsalva maneuver
The Valsalva maneuver can be performed by forcibly exhaling against a closed
glottis (a closed airway), for instance to detect an inguinal hernia or to
clear the ears during diving. In the present study, volunteers and patients
will perform a Valsalva maneuver by blowing into a manometer-controlled device
that allows standardization of the pressure which induces the Valsalva effects.
This measurement is associated with minimal discomfort. Since the pressure may
induce pain around the incision wound, pressure will be adapted to patient
comfort.
Controlled breathing
Volunteers and patients will perform a cycle of metronome-controlled breathing
to mimic ventilation conditions. This is regarded to induce minimal discomfort.
Quick Standing test
Volunteers and patients are asked to quickly change from supine to standing
position. Standing is part of the revalidation program in surgical patients.
However, patients who are unable to stand are excluded from this test.