Pain Management Flashcards
What is pain?
An unpleasant sensory and emotional experience associated with actual or potential tissue damage
Why is having pain an issue in our patients?
1) It’s often under-treated
2) Uncontrolled pain produces SE that we don’t want
3) The treatment of pain has unwanted SE
4) Many patients and providers have misconceptions about the treatment of pain
5) Pain increases the patient’s stay in PACU, ICU, and the hospital in general
What is acute pain?
Pain caused by a noxious stimulus d/t injury, trauma, acute disease process, or abnormal function of muscle or viscera.
Acute pain is almost always ____ in nature and results in _____.
Nociceptive.
neuroendocrine response (stress response with HPA and SNS activation)
Endocrine and CV response to pain
Endocrine: Increased catecholamines Increased cortisol Increased aldosterone and ADH, renin, and angiotensin II Immune system suppression
CV:
Increased HR, BP, SVR, CO, contractility
Enhanced myocardial irritability
Vasoconstriction, including coronary artery constriction
Increased myocardial O2 consumption with decreased myocardial O2 supply (ischemia)
Increased plasma viscosity
Increased water retention
Vasoconstriction and fluid retention increase the workload of the heart
Pulmonary Effects of Pain
Decreased lung volumes (VC, TV,FRC)
Phrenic nerve dysfunction
Inadequate cough (don’t want to agitate the pain)
Inadequate ventilation (will decrease TV, VC, and FRC –> FRC may approach closing volume and cause atelectasis and VQ mismatch)
May have limited movement of respiratory muscles due to spasm of muscles
Decreased ability to clear airway secretions
Susceptible to pneumonias
Increased total body O2 consumption which increases respiratory workload
Increased CO2 production
Heme Effects of Pain
1) Hypercoagulability
- Natural anticoagulants decrease and natural procoagulants increase.
- Inhibition of fibrinolysis
- Increased platelet reactivity/ adhesiveness
- Increased plasma viscosity
- Increased risk of DVTs and vascular grafting failure, poor wound healing, MI risk
2) Immunosuppression
- Potentiates postoperative immunosuppression (poor wound healing)
- Depressed lymphocyte response
- Decreased cell mediated immunity
- Alterations in balance of T-helper cells
- Increased interleukins and cytokines
GI/GU Effects of Pain
GI
- Hypersecretion of gastric acid
- Slowed GI motility (risk of aspiration and paralytic ileus)
GU:
- Urinary retention
Neurendocrine Response to Pain
Basically reacting as if the body is in stress:
Increased catecholamines Increased catabolic hormones Decreased anabolic hormones Increased ADH, Aldosterone, renin, and angiotensin II Increased cortisol Increased glucagon Decreased insulin Sodium and water retention Increase blood glucose Free fatty acids Ketone bodies Lactate
What is chronic pain?
Pain that serves no purpose
Pain that persists beyond the usual coarse of an acute disease after a reasonable amount of time for healing to occur.
This may be a predictor of transition to chronic pain
Poorly controlled acute pain.
Intensity of acute pain is significant predictor of chronic pain.
Chronic Pain may occur after these procedures
Limb amputations (30-83%) Thoracotomy (22-67%) Sternotomy (28%) Breast surgery Gallbladder surgery
Chronic pain is associated with an imbalance in _____
Neuromodulation controls
- Attenuated neuroendocrine response (unlike acute pain)
- Exhausted supplies of endorphins and serotonin
- Predominance of C-fiber stimulation
Chronic pain is associated with ____ in the periphery
chronic inflammation
Continuous release of inflammatory mediators in the periphery sensitizes functional nociceptors and activates dormant nociceptors
There is sensitization of nociceptors and hyper excitability.
Functional changes occur in the dorsal horn of the spinal cord (neuroplasicity) .
Dormant nociceptors are activated.
Recruitment of additional nerve fibers and pathway tracts. Pain is perceived as more painful.
Reflexes can create excessive muscle tension, with actual disruption of microcirculation
Causes of cancer pain
1 - tumor invasion of the bone
Treatments of cancer (chemo and radiation) can also result in cancer pain (tissue destruction)
Physical and psych components of cancer pain
Physical—worse due to loss of sleep, appetite, nausea & vomiting
Psychological—heightened anxiety, feelings of loss, low self-esteem, changes in life goals, disfigurement
What is allodynia?
Pain in response to a stimulus that shouldn’t normally cause pain
Every treatment plan for pain must be directed at
controlling the pain and the underlying pain process
Benefits of adequate post-op pain control
Reduction of the stress response Shorter times to extubation, shorter ICU stay Improved respiratory function Earlier return of bowel function Early mobilization, decreased risk DVTs Early discharge Reduction in sensitization, neuroplasticity, wind-up phenomenon, and transition to chronic pain Earlier enteral nutritional intake Increased patient satisfaction
When does post-op pain control begin?
Pre-operatively!!
Goal is to prevent pain before it happens.
Who requires that we do a pain assessment of our patients?
JCHO
Respiratory and routes of opioid administration
Incidence of respiratory depression does not vary across routes. You get depression despite whatever route you choose.
Preferred routes of opioid administration
IV**
Then sublingual or rectal (avoid first pass effect)
Opioids exert their effects via these receptors
Mu and Kappa
Is there an analgesic ceiling with opioids?
No.
The dose is only usually limited by tolerance or SE.
Most common drugs for PCA use
Morphine and hydromorphone
NSAIDs work by inhibiting ____
COX
By using NSAIDs with opioids, the pain response is attenuated in both these locations
The spinal cord (opioids) and in the periphery (NSAIDs)
