Lecture 4, pre- and postoperative care Flashcards
Most common time of death related to anesthesia
Postoperative period
Why cats has 2 times higher risk for anesthesia-related mortality?
Smaller animal (hypothermia, overhydrating)
Uncooperative behaviour
Prone to laryngospasm
Sensitivity to local anesthesia drug toxicity
Reduced glucuronidation (slower drug metabolism)
ASA I, animals condition, examples
Healthy with no discernible disease
Patient is undergoing an elective
procedure (e.g.ovariohysterectomy, declaw, castration)
ASA II, animals condition, examples
Healthy with localized disease or mild systemic disease
Patellar luxation, skin tumor, cleft palate without aspiration pneumonia.
ASA III, animals condition, examples
Severe systemic disease
Pneumonia, fever, dehydration, heart murmur, anemia
ASA IV, animals condition, examples
Severe systemic disease that is life threatening
Heart failure, renal failure, hepatic failure, severe hypovolemia, severe hemorrhage
ASA V, animals condition, examples
Moribund; patient not expected to live longer than 24h with or without surgery
Endotoxic shock, multiorgan failure, severe trauma
Details that require attention in preoperative care
- Thorough anamnesis
- Full clinical examination
- Laboratory data
- Patient stabilization
- Determination of surgical risk
- Client communication
Preoperative care, anamnesis vitae
Basic information
- species
- breed (genetics, anatomy)
- age (diag. tests warranted?)
- gender
Lifestyle
- diet, exercise, environment
Preoperative care, anamnesis morbi
Reason for surgery (chief complaint)
Clinical signs and duration
Past medical problems and treatments
Current medical problems and treatments
Prior anesthesia
- used drugs, complications, recovery
Why it’s important to know the breed?
Breed has to be taken into consideration due to possible anatomical differences and other genetic predispositions
Brachycephalic breeds
- Small hypoplastic trachea, elongated, soft palate, stenotic nares
- Laryngeal mucous membrane prone to swelling
- Increased tonus of n. vagus
- Predisposition to gastroesophageal reflux
- Higher risk of hypoxia
Toy breeds
- Hypothermia
- Catheter placement
- Questionable accuracy of
monitors - Accuracy of drug dosages
- Hands-on assessment limited
during anesthesia
Giant breeds
- Lower drug dosages required
- Considered geriatric at a
younger age - Patient handling more difficult
Herding breeds
Mutations in the MDR-1 gene (prolonged effect of some drugs)
Boxers
Drug sensitivity (acepromazine)
Greyhounds (+ other sighthounds)
Drug sensitivity, prolonged
recovery from some drugs (propofol, barbiturates)
Other similarly lean-muscled breeds may also appear more sensitive to lipophilic drugs (most anesthetic drugs)
Miniature schnauzers
Sick sinus syndrome
Dobermans
Abnormal concetrations of von Willebrand factor (73%)
- Buccal mucosal bleeding time may
be measured
Anamnesis, age
Pediatric and geriatric patients at a higher risk – smaller drug dosages
required
What to take in consideration in case of pediatric patients?
- Immature organs and defence mechanisms
- Prone to hypothermia, hypoglycemia, regurgitation
- Blood loss more dangerous
What to take in consideration in case of geriatric patients?
- Reduced response to hypercapnia, hypoxemia
- Slower metabolism and healing, decreased organ function
- Prone to hypothermia, regurgitation
Principles of preoperative care
Clinical examination
↓
Diagnostic tests
↓
Stabilization:
- Optimizing hemodynamics if possible
- Optimizing respiratory function (also preoxygenation)
- Optimizing hydration status (fluid therapy)
- Preoperative fasting
- Analgesia and sedation
- Thermoregulation
- Positioning
Why is clinical examination important?
Benefits of evaluating patients before general anesthesia are often underestimated
Evaluation of risks and the necessity of further diagnostic tests
Full clinical examination always warranted, but sometimes not
possible
Clinical examination cardiovascular system
Heart auscultation
Pulse (peripheral)
Mucous membranes
Clinical examination of respiratory system
Breathing pattern and noises
Lung auscultation
Mucous membranes
Palpation of trachea
Clinical examination of hydration status
Mucous membranes
Skin turgor
Eyes
Clinical examination of GI and urinary system
Abdominal palpation
Clinical examination of integumentary system
Appearance of skin
Signs of inflammation/infection?
Clinical examination of CNS
Assessment of mentation
Neurological examination
2 basic things we check during clinical examination
BCS and temperature
Which preoperative diagnostic test are recommended?
Choise of tests depends on the patient (clin. exam) and the owner.
PCV, total protein, glucose, urea at least
Hematology, biochem, urianalysis
Xrays, us, mri, ct
Further tests e.g. ECG, blood typing
Patient stabilization
All patients should be stabilized prior to sedation if possible
* Hemodynamics
* Respiratory function
* Hydration status
Some emergency patients in critical
condition need immediate surgery,
but most benefit from preoperative
stabilization
Preoperative fasting
- Reduced amount of contents in the stomach → reduced possibility of
vomiting, gastrointestinal reflux and consequently aspiration - Care should be taken when dealing with (risk of dehydration,
hypoglycemia): - Pediatric patients
- Cachectic patients
- Concurrent diseases (fever, diabetes, etc. [polyuria])
- Different species
- Fasting of 2-4 hours for water and 6-8 hours for food should be
enough in most cases
Sedation and analgesia; choice of drugs depends on…
- Patient characteristics (age, breed, concurrentdiseases, etc.)
- Expected severity of pain
- Surgical procedure
Sedation and analgesia
- Optimal pain control during and after anesthesia is of critical
importance (not all anesthetics provide analgesia!) - Multimodal anesthesia and analgesia are preferred
- Both NSAIDs and opioids often used unless contraindicated
- A familiar anesthetic protocol is often the best anesthetic protocol
Why pre-oxygenation (100%) is warranted before sedation?
To prevent hypoventilation/hypoxemia
When is oxygenation started and how long it lasts?
- Started before induction and
intubation - Usually lasts 3-5 minutes and stopped immediately before intubation
- Administration of oxygen is continued after intubation
What is the most common complication of anesthesia?
Hypothermia
Warming should be started as soon as possible
What hypothermia may cause?
Hypoxia, prolonged recovery from
anesthesia, an increased infection risk, worse cardiovascular
parameters
Ways of thermoregulation during surgery
- Warm room temperature – most effective
- Warm water – also effective
- Electric heating bags/table – always warranted
- Warm infusions – not very effective (increase by ~0,5 oC)
- Infrared light – not recommended without a folium blanket (may
promote inflammation)
What is the purpose of intraoperative fluids?
- Maintenance of hemodynamics
- Maintenance of the catheter
- Amortization of fluid and blood loss
Intraoperative fluid guidelines
American Animal Hospital Association guidelines:
* Starting dose of 5 ml/kg/h for dogs and 3 ml/kg/h for cats
* Can be reduced 25% each hour (unless fluid/blood loss)
Most often used – Ri-Lac or Hartmann’s solution (not NaCl 0,9%)
In case of hypotension
* Crystalloid bolus 10-30 ml/kg for 10-15 min (depending on mean arterial pressure)
* Colloid bolus 2-10 ml/kg for 5-10 mins (depending on mean arterial pressure)
What to take into consideration when positioning the patient
- Intubation, catheterization
- Procedure, monitoring
- Well-being of the patient
Immediate postoperative concerns
- Pain
- Anxiety
- Cardiorespiratory function
- Blood pressure
- Oxygen saturation
- Temperature
- Procedure-related factors
- Wound protection
- Postoperative period should be made as pleasant as possible
Postoperative care, patient has to be closely monitored until it:
- Has been extubated
- Is laying on sternum, head elevated
- Is able to swallow, has normal ocular reflex
- Has a strong and regular peripheral pulse
- Has an oxygen saturation of >94%
- Has no suspicion of upper airway obstruction
- Has effective analgesia
- Has no evident bleeding
Highest death rate 3 hours after extubation
Postoperative care
- Pain management
- Nutritional management
- Wound care (protection, antibacterials)
- Care related to surgical procedure
- Exercise restriction
- Immobilization
- Other care possibilities
- Home care – instructions necessary!
Postoperative pain management
Better options for analgesia in the
clinic – should be left as an inpatient
until pain under control
Options for analgesia at home:
* NSAIDs
* Tramadol
* Fentanyl/lidocaine patch
* Ca++ channel blockers (e.g. gabapentin)
* Etc.
Length of treatment is determined by the procedure and the patient
Procedure-related care
- Postoperative care depends on the surgical procedure and the
condition of the patient - Catheterization
- Feeding tubes
- Limb immobilization
- Laser therapy
- Physiotherapy
- Etc.
Wound care
- Owner must be instructed in detail
- Wound care should be provided daily (usually up to 14 days)
- Wound exudate should be removed
- Cleaning with physiological solution is recommended
- Wound gels may be applied
- Suture material usually removed after 7-14 days
- A follow-up is also warranted in case an intradermal pattern was used
