Identify complications with the above rhythm strip.

The answer to question 1

A
Undersensing is the inability of the pacemaker to sense spontaneous myocardial depolarizations. Undersensing results in competition between paced complexes and the heart's intrinsic rhythm. This malfunction is manifested on the electrocardiogram by pacing artifacts that occur after or are unrelated to spontaneous complexes. Oversensing occurs as a result of inappropriate sensing of extraneous electrical signals that leads to unnecessary triggering or inhibition of stimulus output, depending on the pacer mode. The source of these electrical signals can range from tall peaked T waves to external electromagnetic interference in the critical care environment. The implantable cardioverter defibrillator system consists of leads and a generator and is similar to a pacemaker but with some key differences. The leads contain not only electrodes for sensing and pacing but also integrated defibrillator coils capable of delivering a shock. If the pacing stimulus fires but fails to initiate a myocardial depolarization, a pacing artifact will be present but will not be followed by the expected P wave.

The answer to question 2

D
To ensure accurate readings, the difference between injectate temperature and body temperature must be at least 10  C, and the injectate must be delivered within 4 seconds, with minimal handling of the syringe to prevent warming of the solution. This is particularly important when iced injectate is used.

The answer to question 3

C
Discoloration of the fingers is an indication of peripheral cyanosis. Central cyanosis occurs when the unsaturated hemoglobin of arterial blood exceeds 5 g/dL and is considered a life-threatening situation. Clubbing refers to an abnormality of the fingers caused by chronically low blood levels of oxygen often related to a heart or lung disease.

The answer to question 4

C
A definitive diagnosis of a pulmonary embolus requires confirmation by a high-probability V/Q scan, an abnormal pulmonary angiogram or computed tomography scan, or strong clinical suspicion coupled with abnormal findings on lower extremity deep venous thrombosis studies.

The answer to question 5

A
Postoperative fever is fairly common after cardiopulmonary bypass. However, persistent temperature elevation to greater than 101  F (38.3  C) must be investigated. Sternal wound infections and infective endocarditis are the most devastating infectious complications, but leg wound infections, pneumonia, and urinary tract infections also can occur. A potentially lethal complication, cardiac tamponade may occur after surgery if blood accumulates in the mediastinal space, impairing the heart's ability to pump. Signs of tamponade include elevated and equalized filling pressures (e.g., central venous pressure, pulmonary artery diastolic pressure, pulmonary artery occlusion pressure), decreased cardiac output, decreased blood pressure, jugular venous distention, pulsus paradoxus, muffled heart sounds, sudden cessation of chest tube drainage, and a widened cardiac silhouette on radiographs. The risk of delirium is increased in cardiac surgery patients, especially elderly patients, and is associated with increased mortality rates and reduced quality of life and cognitive function. Nursing staff can play a critical role in the prevention and recognition of delirium.

The answer to question 6

C
Causes of metabolic coma include drug overdose, infectious diseases, endocrine disorders, and poisonings. Structural causes of coma include ischemic stroke, intracerebral hemorrhage, trauma, and brain tumors.

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