Centers for Oral Care
New England & New York
Animal Dental Health Services
www.animaldentistrysolutions.com
No. 21~08March2017
DH DeForge, VMD
Fellow of the Academy of Veterinary Dentistry
Blood Pressure
Monitoring Under Anesthesia in Companion Animals
“There are no safe anesthetic agents; there are no safe
anesthetic procedures; there are only safe anesthetists.” – Robert M. Smith, MD
Abstract: Blood pressure monitoring under anesthesia is a very important
parameter to evaluate circulatory changes that could cause hypotension. Coupled with % hemoglobin concentration;
electrocardiogram; end tidal C02 measurement; body temperature; and physical
vital signs monitored by the anesthesia monitoring assistant--- the anesthesia
journey can be well evaluated preventing unexpected difficulties from
occurring.
Anesthesia Monitoring-Non-Invasive Blood Pressure: A
Discussion
ACVA Monitoring Guidelines
Update, 2009
Recommendations
for monitoring anesthetized veterinary patient
CIRCULATION
1)
Palpation
of peripheral pulse to determine rate, rhythm and quality, and evaluation of
mucous membrane (MM) color and capillary refill time (CRT).
2)
Auscultation
of heart beat (stethoscope; esophageal stethoscope or other audible heart
monitor). Continuous (audible heart or pulse monitor) or intermittent
monitoring of the heart rate and rhythm.
3)
Pulse
oximetry to determine the % hemoglobin saturation.
4)
Electrocardiogram
(ECG) continuous display for detection of arrhythmias.
5)
Blood
pressure:
a.
Non-invasive
(indirect): oscillometric method: Doppler ultrasonic flow detector
Invasive (direct): arterial catheter
connected to an aneroid manometer or to a transducer and oscilloscope. Parks Medical Electronics/Oregon
The Doppler
Parks Medical Electroni
Sphygmomanometer
Assorted
Blood Pressure Cuffs
|
The Doppler
is used for detecting blood flow acoustically and for making
blood-pressure measurements indirectly using an inflatable cuff and sphygmomanometer.
The method is like that used on
humans; the Doppler functions as a stethoscope. Systolic pressure is
measured by reading the pressure on a sphygmomanometer when the blood flow
sound first returns as cuff pressure is lowered. Normally, only systolic
pressure is measured. Diastolic pressure measurements can be made, but they are
not very accurate and require lots of subjective judgment. Parks Medical Electronics, Inc
The Importance of Blood
Pressure Measurement under anesthesia
Blood pressure should be routinely
measured on any patient undergoing general anesthesia. The best way to prevent
hypotension is to detect changes in blood pressure as soon as they begin.
The information obtained
via patient monitoring is used to achieve three goals:
1. Ensure
adequate tissue perfusion with well-oxygenated blood
2. Prevent
pain before, during, and after a surgical procedure
3. Provide
a smooth and rapid recovery from anesthesia/surgery.
What is a Normal
Blood Pressure Reading in Companion Animals?
What is a normal and what is an abnormal blood pressure
reading in dogs and cats? Normal systolic arterial blood pressure ranges from:
110-160 mm of mercury
(Hg). Normal diastolic arterial blood pressure ranges from: 60-90 mm of Hg. Normal MAP is in the range from
85-120 mm of Hg.
We cannot measure cerebral blood flow during anesthesia, so blood
pressure, is all that is possible to measure the adequacy of cerebral blood
flow and provide safe margins to prevent potentially damaging hypotension.By monitoring the anesthetized patient, the anesthetist obtains information in the following areas:
Physiologic condition of the patient (eg, cardiovascular,
respiratory, and metabolic systems)
Patient’s response to anesthesia, including anesthetic depth and
level of analgesia.
In addition, assessing the status of the anesthetic equipment
ensures its proper function, helping the anesthetist prevent iatrogenic crises
that can jeopardize the patient’s health. Jeff Ko, DVM, MS, Diplomate ACVA
Commentary
from Dr. DeForge:
The
journey in anesthesia can be a journey with safety if there is a combination of
excellent pre-anesthesia testing coupled with excellent anesthesia
monitoring. This report talks about one
of the monitors of blood pressure called the Doppler System.
The
Doppler system is excellent and is used commonly in conjunction with other
blood pressure measuring systems in toy breeds and in the cat during anesthesia.
This
report has featured comments from Dr. Jeff Ko, a well known veterinary
anesthesiologist; a position statement from the American College of Veterinary
Anesthesiology; a discussion of the Parks Medical Doppler; and an introductory
quote from the “Father of Pediatric Anesthesiology,” Robert M. Smith, MD. Dr. Smith’s words should echo in all human
anesthesia and veterinary anesthesia operatories as a reminder of the
importance of the human hand in providing ultimate safety in anesthesia.
