Page 278 - Clinical Application of Mechanical Ventilation

244 Chapter 9

TABLE 9-1 Conditions That Affect the Heart Rate

Conditions That May Cause Tachycardia Conditions That May Cause Bradycardia

Hypoxemia Sudden hypoxia and/or vagal stimulation during
endotracheal suctioning
Hypovolemia Inadequate coronary blood flow

Pain Heart block
Anxiety and stress Abnormal SA node function

Fever Hypothermia

Drug reaction (e.g., epinephrine) Drug reaction (e.g., morphine sulfate)
Myocardial infarction
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Hypotension. Hypotension, lower than normal blood pressure, may be due to absolute
Hypovolemia, positive
pressure ventilation, and hypovolemia (blood loss), relative hypovolemia (shock), or pump failure (CHF). When
pump failure are conditions hypotension occurs during mechanical ventilation, it is often associated with excessive
that may cause hypotension.
intrathoracic pressure, peak inspiratory pressure, and lung volume. Hypotension is one
of the complications of positive pressure ventilation or positive end-expiratory pressure.
Table 9-2 outlines the conditions that affect the blood pressure.

Respiratory Frequency

The normal spontaneous respiratory frequency for adults is 10 to 16 breaths per minute.
An increased respiratory frequency (tachypnea) may be an early warning sign of

TABLE 9-2 Conditions That Affect the Blood Pressure

Conditions That May Cause Hypertension Conditions That May Cause Hypotension
Fluid overload Decreased venous return due to positive
pressure ventilation

Stress Absolute hypovolemia (e.g., blood loss,
dehydration)

Anxiety Relative hypovolemia (e.g., sepsis, shock)
Pain Pump failure (e.g., CHF)

Congestive heart failure

Cardiovascular disease
Polycythemia (cblood viscosity)
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