What is normal blood pressure?

 

'Normal' or 'acceptable' blood pressure varies with age, state of health and clinical situation. At birth, a typical blood pressure is 80/50 mmHg. It rises steadily throughout childhood, so that in a young adult it might be 120/80 mmHg. As we get older, blood pressure continues to rise and a rule of thumb is that normal systolic pressure is age in years + 100. Blood pressure is lower in late pregnancy and during sleep.

 

From this, you can see that a systolic pressure of 160mmHg for an elderly man or 90 mmHg for a pregnant woman may be quite normal. To judge whether any particular reading is too high or too low, we must compare the reading with the 'normal' for that patient.

 

Invasive arterial blood pressure measurement IV CannulasInvasive arterial blood pressure measurement IV Cannulas

 

This technique involves direct measurement of arterial pressure by placing a cannula needle in an artery (usually radial, femoral, dorsalis pedis or brachial). The cannula must be connected to a sterile, fluid-filled system, which is connected to an electronic patient monitor. The advantage of this system is that pressure is constantly monitored beat-by-beat, and a waveform (a graph of pressure against time) can be displayed.

 

Invasive blood pressure measurement

 

Patients with invasive arterial monitoring require very close supervision, as there is a danger of severe bleeding if the line becomes disconnected. It is generally reserved for critically ill patients where rapid variations in blood pressure are anticipated.

 

There are a variety of monitors with invasive blood pressure monitoring for Trauma, critical care and operating room applications. These include single pressure, dual pressure, and multi-parameter (i.e. Pressure / temperature)

 

Invasive Blood Pressure monitors are pressure monitoring systems designed to acquire pressure information for display and processing. This can be used to monitor arterial, central venous, pulmonary arterial, left atrial, right atrial, femoral arterial, umbilical venous, umbilical arterial, and intracranial pressures.

Blood pressure parameters are derived in the monitor's microcomputer system.

 

Usually, systolic, diastolic and mean pressures are displayed simultaneously for pulsatile waveforms (i.e. arterial and pulmonary arterial).

 

cerebral perfusion pressure

 

Some monitors also calculate and display CPP (cerebral perfusion pressure). Normally, a zero key on the front of the monitor makes pressure zeroing extremely fast and easy. Alarm limits may be set to assist the medical professional responsible for observing the patient.

 

High and low alarms may be set on displayed temperature parameters.