Biomedical Engineering Reference
In-Depth Information
procedure. This process is referred to as ''auto trans-
fusion.'' The cell saver receives salvaged blood that has
been suctioned from the surgical site. The blood passes
through filters to remove surgical and cellular debris.
Centrifuge technology is employed to separate the
heavier oxygen-carrying red blood cells from the other
components of the blood. The red blood cells are
processed and stored for auto transfusion.
objects during minute and intricate surgeries. These de-
vices are generally employed when performing pro-
cedures, such as neurosurgery, where structures are often
very small and cannot be viewed clearly with the naked
eye. Surgical microscopes generally contain binocular
lenses, light sources, optic fiber cables, and focusing
mechanisms. Surgical microscopesmust be equippedwith
a mounting or support system in order to be utilized in the
surgical field. A variety of support systems are available,
including mobile floor stands and ceiling mounts.
Pacers and pacemakers
A pacemaker is an electrical pulse generator designed to
support the electrical activity of the heart (Greatbatch
and Seligman, 1988). A pacemaker can be implanted
within a patient or used externally. External temporary
pacemakers are commonly used in cardiovascular pro-
cedures to treat heart conditions such as bradycardia,
atrial and/or ventricular arrhythmias, and cardiac arrest.
The basic pacemaker comprises a pulse generator,
a programmer, and a lead. The pulse generator consists of
the power source and circuitry, which senses the heart's
electrical activity and generates the output. The pro-
grammer allows the clinician to adjust pacing variables
such as pulse rate, amplitude, duration, and the sensitivity
of pulse detection. The lead is an insulated wire that
carries the stimulus from the pacemaker to the heart and
delivers an ECG signal back to the pacemaker.
Safety in the operating room
The hazards associated with medical devices, clinical pro-
cesses, and human error are of primary concern to the
clinical engineer. A prevalence of medical equipment and
staff in the OR, along with the vulnerability of the surgical
patient, creates an environment that requires additional
precautions. Potential hazards associated with OR devices
and technologies are vast and can be encountered in many
forms.Medical equipment, for example, can pose electrical
and/or mechanical hazards to patients and staff. A patient
whose natural resistance to current flow has been com-
promised (perhaps due to an invasive connection to
a medical device) is particularly vulnerable to electrical
hazards. Devices that are mechanical in nature, such as
transport beds and surgical tables, also pose a risk to pa-
tients and staff if they are not used and maintained prop-
erly. It is a responsibility of the clinical engineering
department to implement a program to ensure medical
device safety and to manage risk. The program must
include the preventive maintenance and inspection of
medical devices and systems. It alsomust conformto codes
standards set forth by regulatory agencies such as NFPA,
Underwriters Laboratories (UL), Occupation Safety and
Health Act (OSHA), and the Joint Commission on Ac-
creditation of Healthcare Organizations (JCAHO).
Other hazards associated with technology in the OR
include environmental hazards, such as the spread of
infection due to poor filtration of OR air; biological
hazards, resulting from poor sterilization practices; and
radiation hazards from diagnostic machines and thera-
peutic devices that release radiation (Bronzino, 1992).
A lack of knowledge and communication within the
clinical staff significantly increases the likelihood of in-
juries in the OR. Familiarity with medical devices,
technical processes, and awareness of emergency pro-
cedures are key factors in avoiding injury. To meet these
requirements, a clinical engineer must provide, or parti-
cipate in, the in-servicing of new equipment, continual
user training, and incident reporting and evaluation.
Adequate preparation requires that the medical staff
be properly trained to respond to the following
emergencies:
Ventricular assist devices
The primary aim of a ventricular assist device (VAD) is
circulation support. When the myocardium is damaged,
the heart is unable tomaintain the required cardiac output
and blood pressure to maintain blood flow. A VAD is
implemented to relieve the workload of the myocardium.
Another use of the VAD is ventricular assistance. Patients
with heart failure, which can be reversed if the heart is
given sufficient time to recover, are candidates for a VAD.
Using a VAD is also common after patients undergo car-
diopulmonary bypass or any other traumatic heart surgery.
AVAD can assist in the recovery of the right or left ven-
tricle (RVAD or LVAD) or both ventricles (BIVAD). An
LVAD diverts blood from either the left atrium or left
ventricle, sends the blood through a pump, and then
returns the blood to the aorta. The RVAD operates in the
same manner, with the blood diverted from the right
atrium and returned into the pulmonary artery.
Microscopes
Due to the spread ofmicrosurgical procedures through the
various surgical disciplines, the surgical microscope has
become a valuable tool in the OR. Microscopes are used to
provide magnification and illumination in order to view
