Travel Reference
In-Depth Information
Ifshockissoseverethatnopulsescanbefelt,theheartratecanbedeterminedbylisten-
ing with a stethoscope placed between the left nipple and the sternum. Each heartbeat is
accompanied by two heart sounds of slightly different tone (lub-dup, lub-dup). Occasion-
ally a faint third sound may be heard (lub-dup-dup, lub-dup-dup.) Although heart sounds
in normal persons can be heard with the unaided ear pressed against the chest, the heart
sounds are usually faint in shock and a stethoscope is often needed. A little prior practice
by examiners—even listening to their own heart—is useful.
The normal resting heart rate ranges from fifty (in a few well-conditioned individuals)
toninetybeatsperminute.Theheartrateisslowerduringsleep.Athighaltitudetheresting
heart rate may be as high as 100 beats per minute during the first few days of acclimatiza-
tion.
Normally the heart rhythm is regular, but in young individuals it may change with res-
piration—speeding up during inspiration, slowing during expiration. Such variation is nor-
mal, and when persons hold their breath, the rhythm becomes completely regular.
Arterial and Venous Pressure
Whenthepulseisbarelypalpable,thebloodpressureisusuallylow.Strong,“bounding”
pulsesusuallyindicateanormalbloodpressureandnormalheartaction.Arterialpulsesare
usually equal in both wrists, both sides of the neck, and both sides of the groin. Absence of
a pulse on one side indicates arterial obstruction or injury.
When healthy persons are lying flat, the partially or fully filled neck veins can be seen
extending from the middle of the collarbone (clavicle) to just below the lower jaw. When
the person is sitting upright or even partially upright (semirecumbent), filled neck veins
should not be visible above the clavicle. Visible, distended neck veins in an upright posi-
tion are abnormal and usually indicate heart failure or obstruction of venous blood flow to
the heart.
Accuratemeasurementofbloodpressurerequiresabloodpressurecuff(sphygmomano-
meter) and stethoscope. The cuff should be wrapped snugly around the arm above the el-
bowandinflatedtoapressureofabout180mmHgoruntiltheradialpulsedisappears.The
stethoscopebellshouldbeplacedovertheinneraspectoftheelbowcreasewiththearmex-
tended.Thepulsationsofthebrachialarterycanoftenbefelthere,andthebestpositionfor
the stethoscope is over the artery. As the pressure in the inflated cuff is allowed to fall by
slowly releasing air through the valve on or near the bulb, a thumping sound synchronous
with the pulse appears. The pressure indicated when the sound is first heard is the systolic
bloodpressure.Thepressureatwhichthesoundcompletely disappears asthecuffpressure
continues to fall is the diastolic blood pressure. Normal blood pressure ranges from 105 to
140 mm Hg systolic and from 60 to 80 mm Hg diastolic.
If the radial pulse can be felt and a stethoscope is not available, the systolic blood pres-
sure can be approximated by inflating the cuff and allowing the pressure to fall until the
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