PATIENT PREPARATION

CHAPTER 2 Part 1

PATIENT PREPARATION

The RVT has numerous responsibilities in the pre-anesthetic period. The pre-anesthetic period is the period immediately preceding the induction of anesthesia.

This period can be from minutes to weeks

PRE-ANESTHETIC RESPONSIBILITIES OF AN RVT:

obtaining patient history reviewing consent form with an owner making sure the patient is fasted performing a physical exam drawing blood and running diagnostic tests placing an IV catheter calculating drug doses administering pre-medications preparing anesthetic equipment

SEE BOX 2-1 pg. 6 for more info…

FEELING OVERWHELMED?

MINIMUM DATABASE

ANESTHESIA IS NOT A COOKIE CUTTER PROCEDURE: Age, breed, size, & health status play a role in the selection of anesthetic agents and techniques

Every patient should have a minimum database, which would ideally include: HISTORY PHYSICAL EXAM FINDINGS DIAGNOSTIC TEST RESULTS

TAKING THE PATIENT HISTORY

DO’s: Be thorough Be effective at framing questions to gain the most

information Schedule an appointment several days before the

planned procedure DON’Ts:

Don’t ask “yes” or “no” questions For example, how can you reframe this question: “Does

your dog drink a lot of water?” Don’t ask leading questions

For example, how can you reframe this question: “ Your dog doesn’t drink very much water does he?”

TAKING THE PATIENT HISTORY

What questions should I ask? What procedure(s) is/are being performed today?

Confirm the affected limb, confirm tumors to be removed & determine if client want histopathology

How old is your animal? Is there a history of previous illnesses/problems/treatment and

if so, do you have past medical records? Be sure to ask duration, volume/severity, frequency,

character/appearance Is your pet currently ill? What medications has your pet been on? Does your pet have any allergies or a history of drug reactions? Has your pet had any previous anesthetic problems? Is your pet current on vaccines? Is your pet in heat or pregnant?

TAKING THE PATIENT HISTORY

SIGNALMENT: includes species, breed, age, sex, and reproductive status This information influences the anesthetic plan

SPECIES & BREED Each species has unique responses to anesthetic agents.

Drug doses will vary between species. Examples:

Horses and cats are more sensitive to opioids than dogs and ruminants

Cats can tolerate some drugs given alone, while the same drug may cause seizure-like activity in dogs

Large animals are prone to respiratory depression Boxers & giant breeds are more sensitive to acepromazine Sighthounds are sensitive to barbiturates Brachycephalic breeds are difficult to intubate

TAKING THE PATIENT HISTORY

AGE Very young animals-less than 8 wks of age-

are much less capable of metabolizing injectable drugs because necessary liver pathways are not fully developed.

Young animals are also more prone to hypothermia and hypoxia

Geriatric patients-who have reached 75% of the normal lifespan- may have difficulty metabolizing drugs due to liver or renal failure

TAKING A PATIENT HISTORY SEX & REPRODUCTIVE STATUS

Confirming the sex of the animal is especially important in cats

TAKING THE PATIENT HISTORY

SEX & REPRODUCTIVE STATUS For males, confirm the presence of both

testicles in the scrotum

For females, ask about the possibility of pregnancy, the last estrous cycle, check for a spay scar or a tattoo

TAKING THE PATIENT HISTORY

SEX & REPRODUCTIVE STATUS For females, ask about the possibility of

pregnancy. Determine the client’s wishes if the animal

is found to be pregnant

CONSENT FORM

Have the client sign a consent form/estimate. This should be done in person. By phone is an

option, although this is not ideal. Make sure a witness also hears the authorization.

A consent form reviews anesthetic risks, resuscitation options, blood work options, and phone numbers for the owner.

Some forms also state that a drug will be used on their animal in an extra-label manner.

* If possible, have the owner read the estimate and consent form before the day of surgery.

PATIENT DISPOSITION & LEVEL OF CONSCIOUSNESS

Anxious or aggressive animals may require a combination of drugs for sedation

Fearful or aggressive animals may require a different route of medication administration (oral, induction chamber)

PATIENT DISPOSITION & LEVELS OF CONSCIOUSNESS

Level of consciousness refers to the patient’s responsiveness to stimuli or how easily it can be aroused. BAR, QAR Lethargy – mild decrease in LOC & can be

aroused with minimal difficulty Obtunded – more depressed patients that

cannot be fully aroused Stuporous – sleeplike state; can only be

aroused with painful stimuli Comatose – cannot be aroused and is

unresponsive to all stimuli including pain.

PHYSICAL EXAM

HYDRATION STATUS Dehydration increases the risk for hypotension, poor

tissue perfusion, & kidney damagePERCENT DEHYDRATION

PHYSICAL SIGNS

<5% Not detectable

5-6% Mild loss of skin elasticity

6-8% the above + dry m.m., depressed globes within orbits

8-10% The above + more persistent skin tent, increased PCV/TP

10-12% The above + dry, pale m.m, CRT >2sec

12-15% Signs of shock, death

PHYSICAL EXAM

HYDRATION STATUS Ideally, dehydration should be corrected prior to

surgery: (Wt in kg)(1000 mL/kg)(% dehydration)

EXAMPLE:

A 33 lb dog that is 9% dehydrated, needs _______mL

33 lb /2.2 = 15 kg

(15 kg)(1000 mL/kg) = 15,000 mL

(15,000 mL)(0.09) = 1350 mL

PHYSICAL EXAM

EXAMINE STRUCTURES OF THE HEAD ORAL CAVITY:

Check mucous membrane color, CRT: If gums are pigmented check the conjunctiva, inner vulva, prepuce

PHYSICAL EXAM

EYES & EARS Look for signs of dehydration, check

pupillary light reflexes Check the ears for signs of infection, or

growths

PHYSICAL EXAM

AUSCULTATION: listen to the rate, rhythm, and sounds of the heart and lungs Normal resting heart rate:

Dogs: 60-180 Cats: 110-220

Normal respiratory rate: Dogs: 10-30 Cats: 25-40

Rhythm: listen for normal sinus rhythm vs. arrhythmias

Abnormal sounds: crackles, wheezes, evidence of respiratory distress (flared nostrils, open-mouth breathing, respiratory stridor) Listen to all 4 quadrants of the chest

PHYSICAL EXAM

PULSE: assess the strength and the rate The femoral artery is the easiest

location to palpate a pulse Other locations: metatarsal, metacarpal

arteries A strong or weak pulse loosely

correlates with blood pressure Pulse deficits may indicate heart disease

PHYSICAL EXAM

WEIGHT: assign a body condition score (either use 5 scale or 9 scale)

Drug doses and IV fluid rates are based on weight in addition to species. DON’T ESTIMATE. Weigh accurately.

Use a pediatric scale (if available) if <5 kg; use gram scale if <1 kg

Compare current weight to previous weights.

PHYSICAL EXAM

WEIGHT OBESE ANIMALS can experience dyspnea, they

can be difficult to draw blood from, harder to assess hydration status, and difficult to auscultate. Obese animals do NOT need a higher dose of

anesthetics. Although the body mass is larger, the central nervous system is not.

THIN ANIMALS can be at risk for hypothermia and may have an underlying condition causing the weight loss.

PHYSICAL EXAM

OTHER SYSTEMS: Body Temperature: 100.0°-102.5° for dogs

& cats MS: signs of lameness, pain Lymph: evaluate size of lymph nodes Abdomen: evaluate for tense or painful

abdomen, evaluate organ size, presence of fluid or gas

Repro: evaluate testicles, mammary glands, vulva, prepuce

Integument: check for bruising, petechiae, pyoderma

FASTING

Fasting usually begins the night before surgery Adult dog or cat: Withhold food for 8-12 hours before surgery.

Water is withheld anywhere from 2-4 hours before surgery, depending on the veterinarian’s preference.

Neonate and pediatric patients (<8 wks): Much shorter fasting period (depending on species, could be 4-6 hrs, or no fasting) to avoid dehydration or hypoglycemia.

GI surgery: Withhold food for 24 hours, water for 8-12 hours.

Why fast? Fasting is done to avoid vomiting/regurgitation during surgery

or recovery which can cause esophagitis, respiratory obstruction, or aspiration pneumonia.

FASTING

In addition to not fasting long enough, it is not safe to have animals fasted for too long.

This usually refers to animals refusing to eat for various reasons - usually when the surgery is not elective: serious GI obstructions/perforations, or in the situation where 2 surgeries are performed several days apart and the animal does not want to eat between the surgeries.

Prolonged fasting leads to a longer recovery period, delays healing, and puts the animal at risk for other medical problems ( ex: hepatic lipidosis).

Options include hand/syringe feeding, inserting feeding tubes, or total parenteral nutrition.

PATIENT PREPARATION

Be sure the animal is properly identified Use a cage card or ID collar or BOTH

DIAGNOSTIC TESTS

ECG

DIAGNOSTIC TESTS

The extent of the diagnostic testing will depend on the clinic, the owner, and what is ideal for the patient

It is important to provide the most complete and affordable testing available

DIAGNOSTIC TESTS

COMPLETE BLOOD COUNT: PCV and RBC

used to determine the blood’s ability to deliver oxygen to tissues. Increases usually indicates dehydration (which leads to increased viscosity of the blood, poor perfusion and decreased cardiac output). Decreased levels usually indicates anemia. PCV less than 25% in a dog or less than 20% in a cat should be reported immediately

TOTAL PLASMA PROTEIN usually indicates dehydration if increased. Decreased values may indicate

decreased production by the liver or a loss through the renal, hepatic or GI systems. Decreased levels can lead to increased drug potency. Values of less than 4.0 should be reported immediately

BLOOD SMEAR used to evaluate red blood cell & white blood cell morphology and platelet

estimation. Report all decreases in platelet count or abnormal coagulation test results

DIAGNOSTIC TESTS

URINALYSIS: SPECIFIC GRAVITY

used to detect evidence of dehydration or renal insufficiency

GLUCOSE and KETONES used to detect diabetes

WBCs and RBCs can be seen with urinary tract infections and crystalluria(can also be normal in small amounts)

USE THESE RESULTS IN CONJUNCTION WITH OTHER TESTS

DIAGNOSTIC TESTS

CHEMISTRY PANEL: MOST COMMONLY EVALUATED PARAMETERS

PRE-OPERATIVELY ARE: ALT: liver ALP (or ALKP): liver, possibly bone, possibly GI tract BUN: kidneys Creatinine: kidneys Glucose: diabetes screen Electrolytes: Na, K, Ca

The more parameters that are evaluated, the better picture we have of the patient.

DIAGNOSTIC TESTS

CLOTTING TIMES: Not commonly performed for routine procedures

unless coagulopathies are suspected such as in breeds that are commonly affected by hereditary coagulation disorders.

PT, (A)PTT

In-clinic testing is performed by either performing a Buccal Mucosal Bleeding Time (BMBT), a short nail trim to the quick, or placing whole blood in a plain red top. Blood should clot within 4 minutes.

DIAGNOSTIC TESTS

ECGEvaluates electrical activity of the heart,

pattern, rhythm Perform if heart disease is suspected, there is a history of trauma, electrolyte

abnormalities, or if the animal is geriatric

DIAGNOSTIC TESTS

RADIOGRAPHS not routinely done in private practice,

but are indicated with dyspnea, abnormal heart/lung sounds, or history of recent trauma.

HEARTWORM TEST – it is important to know heartworm status before undergoing anesthesia

DETERMINATION OF (ASA) PHYSICAL STATUS CLASSIFICATION

Classification based on history, physical exam, and diagnostics performed

Classification is objective and can change with animal’s status

Correct problems before surgery if possible

Category Physical condition Examples

PIMinimal risk

Normal, healthy animal w/o underlying disease

Spay, neuter, declaw, hip rads

P IISlight risk, minor disease

Slight to mild systemic disturbances; animal compensate

Neonates, geriatric, obese, skin tumors, uncomplicated hernia, local infection

P IIIModerate risk, obvious disease

Moderate systemic disease, mild clinical signs

Anemia, moderate dehydration, fever, low-grade murmur or heart disease

P IVHigh risk, significant disease

Preexisting systemic disease

Severe dehydration, shock, uremia, high fever, severe heart or lung disease, diabetes, emaciation

P VExtreme risk, moribund

Life threatening disease that may not be corrected by surgery, animal may not survive 24 hrs

Advanced heart, liver, kidney, lung, or terminal disease, severe shock, head injury, severe trauma

What anesthetic status would you give this dog?

2yr old, mixed breed intact male weighing 12lbs; BCS: 2/5,T-103.5, HR-160, RR-40; 8% dehydratedBloodwork: PCV: 35%, TP: 7.6 g/dl

Preanesthetic Pic of the Day

Based on the picture, what anesthetic category would you place

Oscar in?