Page 298 - ACCCN's Critical Care Nursing

Cardiac Rhythm Assessment and Management 275

● identification of return of spontaneous rhythm
BOX 11.4 Oversensing: causes and ● assessment of haemodynamic adequacy during both
management paced and spontaneous rhythms (BP, CO, perfusion,
symptoms)
Causes: ● strip documentation of rhythm 6-hourly and daily
● Muscle potentials other than QRS complexes: 12-lead ECG
● Cardiac: T waves, U waves, P waves ● daily chest X-ray to confirm position of wire/absence
● Non-cardiac: shivering, fasciculations, seizure activity, of complications
any skeletal muscle movement ● checking and tightening of all connections (leads to
● External electrical interference: bridging cable, bridging cable to pulse generator) at
● Electrocautery, TENS machines commencement of shift and during all pacing adverse
● Electrical devices (rare) events
● Movement of the connecting pins at the connection to the ● confirmation of battery status each shift
pulse generator (common). ● performance of pacemaker threshold assessment each
shift or daily.
Management:
● Reduce sensitivity (turn sensitivity to higher number)
● Consider disabling the sensitivity altogether (i.e. asynchro- Protection Against Microshock
nous, VOO, AOO, DOO mode) Patients with temporary pacemakers require microshock
● Consider reversing the polarity of the wires (positive to protection. Normally, small electrical stimuli (e.g. static
negative) electricity applied to the body) dissipate through body
● Remove the source of interference where it can be tissues and never reach sufficient current density at the
identified. heart to produce arrhythmias. However, pacing wires
provide a direct route to the heart, so that even minor
electrical sources may achieve sufficient current density at
the heart to precipitate arrhythmias. Protection strategies
include nursing patients in body- and cardiac-protected
rhythm. Electromagnetic interference resulting in over- areas, insulating external connector pins when pacing is
sensing may arise from a variety of causes, originating not in use, and using rubber gloves at all times when
from the patient (muscle movement) or external sources handling pacing wires. 70
(devices). The sources of oversensing 22,51,70,71 may be dif-
ficult to establish clinically but should be sought and
corrected where able. Causes and management of over- Battery Depletion in a Temporary Pacemaker
sensing are detailed in Box 11.4. A standard 9V battery might be expected to power a tem-
porary pacemaker for up to a week, although this is vari-
An important distinction must be made between failure able depending on the device, the mode, rate, and output
to pace and oversensing (see Figures 11.44 and 11.45). settings, the percentage paced, and the impedance of the
In both complications the pacing spikes do not appear pacing leads. Additionally it is often not known whether
when expected and may therefore be indistinguishable a new battery was inserted into the pacemaker at the
from each other. Clearly the management of the two commencement of treatment for the current patient.
complications is different, and so prompt, accurate
differentiation is important to ensure appropriate Temporary pacemakers provide indications of depleting
management. battery status; these are usually displayed when there is
less than 24 hours of battery life remaining: (a) flashing
NURSING PRACTICE battery icons may appear on the digital screens of newer
Care, monitoring and management of the patient and the generation devices; (b) on both new and older non-
pacing system largely fall to the nursing staff of critical digital screen devices, the pacemakers will stop supplying
care units. Nurses must ensure ongoing monitoring of power to the flashing sense/pace LEDs. Battery replace-
pacing performance and the detection of pacing abnor- ment should be undertaken as soon as reasonably pos-
malities, the integrity of the pacing system, the avoidance sible as these indicators are not obvious until looked
of clinical situations or physical changes that may alter for, so some time may have elapsed before detection
pacing effectiveness, patient safety, and the prevention of by staff.
complications. Changing the battery on a temporary device carries the
risk of interrupting pacing which may be disastrous in the
Nursing responsibilities in the care of the patient with a
pacemaker include: pacemaker-dependent patient. Although the time taken
to change a battery may be brief, additional significant
● pacemaker site inspection for inflammation/swelling/ time may be lost if the device ‘powers down’ during the
haematoma battery change. It is worth noting, however, that tempo-
● avoidance of hip flexion and rest in bed if femoral rary pacemakers carry a small stored charge which is
insertion enough to sustain pacing for about 10 seconds. If a well-
● vital signs, circulatory observations, etc. at intervals rehearsed procedure is undertaken, battery change can be
appropriate to the overall patient context performed without interrupting pacing for even a single
● confirmation of capture and sensing beat. An understanding of the behaviour of the device in