Intraoperative Consideration Flashcards
Hypoxemia
Complication that can result from all other respiratory complications
Can easily be assessed through pulse oximetry and/or ABG
When there is inadequate oxygenation for the heart it will increase the workload of the heart and result in an increase in both blood pressure and heart rate
Coughing
Adequate anesthesia should be used to prevent coughing
When you are removing the ability for the patient to cough you are also removing their ability to clear secretions, meaning that we need to suction in order to reduce the chance of aspiration
Breath Holding
Usually noted during inhalation induction only
Tends to be temporary and will disappear as anesthesia deepens
Airway Obstruction
Common in unconscious patient whose head/neck allows for the tongue to fall backwards
Neck flexion/jaw thrust will help to alleviate this
Oropharyngeal and endotracheal airways will prevent this
What type of ETT can be used in order to help prevent the kinking of the ETT
Armored ET tubes or careful visualization of prone pts will preclude kinking of ET tubes.
Laryngospasm
Can only occur in a spontaneously breathing non-intubated patient
The vocal cords will shut resulting in stridor, obstruction, and low or absent flow rates
If the laryngospasm is only for a short period of time then you can just wait it out, if the laryngospasm is lasting longer then you can use Lidocaine in order to help the vocal cords relax
Laryngospasm Causes
Causes include the irritation of the airway during light anesthesia
Treatment for this includes the removal of the irritation, increasing anesthesia, and/or intubation
Hypoventilation
Will lead to hypercapnia and subsequently to hypoxemia
Can be avoided
The PETCO2should alert us to hypercapnia
Hypoventilation Causes
CNS depression
Inadequate recovery from muscle relaxant
Small minute volume etc.
Hypoventilation Tx
Ventilation from the machine or from a bag/mask and then the cause can be dealt with
Bronchospasm
Susceptible patient should be pretreated with bronchodilators
These drugs (Ventolin etc) can also be given intraoperatively
Some anesthetic agents may cause mast cell release of histamine but other are well known bronchodilators (ISO)
Barotrauma
Airway pressure during controlled ventilation can become high enough that it leads to a pneumothorax in compromised chronic lung patient and in a trauma patient
Surgical procedure and position can increase this risk
What will increase the risk for aspiration
- Pregnancy
- Pyloric or interstitial obstruction
- Diaphragmatic hernia
- Esophageal Diverticula
- Massive Obesity
- Damaged airway protective reflexes
Esophageal Diverticula
Holes/pouches in the esophagus
More common in chronic alcoholics
Aspiration pH
When the aspirated material is acidic enough (pH 2.5) there will be an immediate bronchospasm and tracheal damage
Chemical pneumonitis can be seen on the chest x-ray in 12-24 hours
ARDS may result which will increase respiratory rate and heart rate and will result in crackles and wheezes
RSI and Aspiration
Rapid sequence induction can help to minimize the risk of aspiration
If surgery can be delayed, then the stomach should be emptied and/or agents should be used that will help to reduce acidity
When people have GERD they will always be intubated due to the risk for aspiration, surgery may also be delayed in order to have time to empty out the stomach
Aspiration of solids
Aspiration of solids may cause blockage and absorption atelectasis distal to the blockage
Phenylephrine
Phenylephrine is generally neither chronotropic nor inotropic
What to do is aspiration has already occurred
Intubate
Suction
Ventilate with PEEP
Antibiotics
Possible bronchoscopy removal of foreign bodies should be considered
What May Cause Hypotension
Induction will often cause a 10-15% reduction in the blood pressure of healthy patients
When you are intubating it may cause hypertension, and once you have intubated hypotension may occur
When people have a cardiovascular disease there is an even greater risk for hypotension
Certain agents may also result in the depression of the circulatory system
Hypovolemia Risk
Surgery may result in hypovolemia
This may be due to a decrease in venous return due to ventilation and/or surgery
When is a drop in blood pressure considered an emergency
Any fall in blood pressure more than 20% is considered an emergency and will require an intervention
What interventions can be used for hypotension
FiO2should be increased to 100% in order to assure oxygen delivery
The cause of hypotension should be corrected
Blood or fluid replacement should be used for hypovolemia
Release of tension pneumothorax and checking pressure on the vent in order to help when there is a decreased venous return
Inotropic agents
Inotropic agents (ex. Dopamine, dig) can be used for cardiac insufficiency
Ephedrine
Ephedrine should be used for low blood pressure
Ephedrine is a sympathomimetic and may cause tachycardia, arrhythmias, angina, ad rebound hypertension
What Could Be a Cause of New Hypertension During Surgery
Noxious stimuli (tracheal intubation)
Hypercapnia and Hypoxemia
Fluid Overload
Surgical Procedure Itself
Surgical Procedure Resulting in Hypertension
Treat through deepening anesthesia
Fluid Overload Resulting in Hypertension
Diuretics such as Lasix
Hypercapnia and hypoxemia Resulting in Hypertension
treat through ventilation and oxygenation
Using Drugs to Decrease Hypertension
Caution should be used when giving drugs are used to decrease both SVR and BP in order to avoid over shooting and causing hypotension
Arrhythmias
Causes include pre-existing heart disease, use of anesthetic agents, and manipulation of the patient, surgical procedures.
Sinus Tachycardia
Usually benign
Possibly caused from administration of atropine, pancuronium, ketamine or from hypercapnia or hypoxemia.
Atrial Flutter or Fibrillation
Pt. needs to be cardioverted or perhaps treated with digitalis
Bradycardia/Asystole
Decrease heart rate is common in anesthesia
Can be treated with atropine (parasympatholytics)
Premature Ventricular Contraction (PVC)
Use of halothane and epinephrine (for reduced blood loss) is associated with PVC
Hypercapnia can be a risk factor
Lidocaine drips can be used to reduce cardiac irritability
Air Embolism
Certain cerebral procedures, cardiopulmonary bypass and intra-uterine procedures can result in air being entrained into the blood vessels.
Air Embolism and Nitrous Oxide
If an air embolism is suspected then the use of nitrous oxide should be immediately discontinued as it may increase the size of the air embolism (compartment shift)
This is because nitrous oxide is so soluble that it will quickly enter into the blood stream and expand the air embolism
Air Embolism and Treatment
Treatment is a FiO2 of 1.0 (possibly hyperbaric)
Anaphylactic Shock
The most serious result of an allergic reaction to an agent or any other substance during the perioperative procedures
Allergies
Pre-existing allergies need to be identified
Epinephrine need to be immediately used in order to maintain blood pressure
Treatment could also include a 50 mL IV bolus of antihistamine (Benadryl)
Nerve Injury
Any peripheral nerve can be injured during anesthesia through stretch or compression
Anesthesia will paralyze the patient so that they will not receive pain and the normal protective muscle tone has been removed
Nerve injury may result in muscle palsy which will require long term physiotherapy
Which nerve are most at risk for nerve injury
brachial plexus
ulnar
peroneal
facial
How to avoid nerve injury
Should try to avoid extreme positions of the head and arm (brachial) and extremes during lithotomy positions (peroneal)
Malignant Hyperthermia
Malignant hyperthermia is life-threatening pyrexia that is cause through a response to an agent
It is a hypermetabolic state that can be cause through all inhaled agents and succ
More common with pediatric than adults
Runs in families
No signs are seen until they are fully present
How can malignant hyperthermia be tested
It can be tested for through a muscle biopsy challenged with caffeine and halothane to see if it hyper-reacts
Malignant Hyperthermia Warning Signs
Hypercapnia (seen on PetCO2),
Increased HR, RR, PVCs
Increased muscle rigidity.
Increase sweating
Severe increased in body temperature.
Combined acidemia, electrolyte imbalance.
What do they do if someone has had a malignant hyperthermia reaction
Only machines that have never had normal inhaled agents (or have been O2 flow purged for 12 hours) can be used on known MHS patients.
Treatment for malignant hyperthermia
Dantrolene during and after the crisis will decrease reaction.
Sodium bicarbonate (2-4 mEq/kg) given conservatively and hyperventilation can treat the metabolic acidosis—watch for hypernatremia and hyperosmolarity.
Dantrolene Dose
Dantrolene at 2 mg/ kg has been used as a prophylactic dose.
2-3 mg/kg as a bolus with repeat boluses totaling 10 mg/kg may abort the crisis.
Maintenance doses of 1-2 mg/kg every six hours for up to three days post crisis should be considered.
