ACUTE PAIN AND THE TRAUMA PATIENTMultimodal Approach to treating

acute pain in trauma patients

Introduction

1. Discussion of the pathophysiology of acute pain.

2. Discuss opiates and adjuvant medicines.

3. Outline acute pain management in patients on chronic pain regimens, including withdrawal avoidance.

4. Discuss relevant regional anesthesia techniques.

What is acute pain?

Caused by noxious stimulation secondary to Injury Disease Abnormal function

Pain is nociceptive vs neuropathic

Pain signals carried by A-delta and C fibers

Nociceptors

Mostly Free Nerve Endings

High thresholds for activation

Intensity of stimulation is proportional to rate of discharge

Four physiologic processes involved in Nociceptive Pain

Transduction

Transmission

Modulation

Perception

Anatomy of Pain Pathways

Three Neuron pathway to get signal from periphery to brain First Order Neurons

Cell Bodies live in dorsal root ganglia Nerve endings connecting to dorsal horn of spine May also synapse with interneurons, sympathetic

fibers and motor neurons

Pain Pathways cont

Pain Pathways cont

Second Order Neurons Synapse with First Order Neurons in dorsal

horn of spine Cross the midline and connect to thalamus Opiates work here Many interneurons interact

Pain Pathways cont

Pain Pathways cont

Third Order Neurons Connect thalamus to postcentral gyrus of

cerebral cortex and others Interneural connections

Pain Perception Emotional Response Feedback (efferent fibers)

Pain Pathways cont

Modulation of Pain

Occurs at: Nociceptors In the spinal cord Supraspinal structures

These can either suppress or facilitate pain

Modulation at Nociceptors

Can become sensitized Increased frequency of response Decreased threshold to stimulation Decreased response latency

Leads to increased Prostiglandin production, producing hyperalgesia

NSAIDS, ASA, steroids work here

Modulation in the Spinal Cord

Function of complex interneuron interaction

“Substance P” increases histamine and serotonin, and other neuroexcititory peptides

Capsaicin and local anesthetics can work here

Modulation in Supraspinal Structures

Facilitators Produce “wind up” via Wide Dynamic Receptors Receptor field expansion Hyperexcitability

Inhibitors Gate Theory from different segments confined

via WDRsGABA drugs work here Supraspinal Descending Pathways

Interact with first and second order neurons at alpha2, opiate, and serotonergic receptors

TCAs work here

Systemic Responses to Pain

Moderate to Severe Pain effects multiple organ systems

Significant influence of Morbidity and Mortality

Mediated via increased sympathetic tone and hypothalamus mediated reflexes

Systemic responses to pain

Cardiovascular Increased HTN, PVR Tachycardia Myocardial irritability Increased oxygen demand Increased CO in normal heart, decreased in

diseased

Leads to MI and dysrhythmia

Systemic responses to pain

Respiratory Increased CO2 production

Increased minute ventilation Increased work of breathingEspecially problematic with lung disease

Decreased chest movement (Splinting) Decreased tidal volume and FRCAtelectasis, intrapleural shunting, hypoxemia

Decreased coughDecreased secretion clearance

Systemic responses to pain

GI Increased sympathetic tone

Decreased intestinal motility Decreased urinary motilityIleus and urinary Retention

Increased Gastric acid productionRisk of aspiration

Gastric distentionFurther decreased FRC

Systemic responses to pain

Endocrine Increased catabolic response

Increased catecholamines, cortisol, glucagon Decreased anabolic hormone

Decreased insulin and testosterone Hematologic

Increased platelet adhesion Decreased fibrinolysis

Hypercoagulability, DVT, PE

Systemic responses to pain

Immune Leukocytosis LymphopeniaInfection and poor wound healing

PsychologicalAnxiety, poor sleep, depression

Opiates and Adjuvant medicines

Opiates have become more commonly used to treat chronic, non-malignant pain

“Normal” doses ineffective Therapeutic dose can vary by 1000% Multimodal approach becomes more useful

Opiates

Mechanism of action Work at mu, kappa, delta, sigma receptors in

spine and supraspinal structures Mu receptors in dorsal horn provide bulk of

analgesia Receptors in medulla produce N/V Supratentorial receptors involved in reward/dug

seeking Inhibit presynaptic release of, and postsynaptic

response to excitatory neurotransmitters in nociceptors Ach sP

Physiologic effects of Opioids

Cardiovascular No significant impairment Bradycardia, vagal mediated Decreased sympathetic flow Histamine release

Respiratory Depress ventilation CO2 respiratory drive blunting (brainstem) Bronchospasm (histamine) Chest wall rigidity

Physiologic effects of Opioids

Cerebral Reduction in cerebral oxygen consumption No change in EEG, no amnesia

GI Decreased peristalsis Sphincter of Oddi contraction

Endocrine Blunt stress response hormones

Goal of Safe Opioid use

Use for mod to severe pain when other agents are ineffective

Monitoring for potential side effects is crucial

Goal is adequate pain control with minimal side effects Typical starting dose for MS is 0.1mg/kg,

increase by 0.05mg/kg Dosing varies significantly; 10X

Goal of Safe Opioid use

Biggest risk of opioids is Resp Depression May or may not be dose dependent Patient may or may not be tolerant

(controversial)

High risk patients: Elderly OSA

Opiod Pearls

Produce state where injury isn’t bothersome Dose varies Decreases spontaneous ventilation and

response to hypercarbia PCA produces less addiction than RN

controlled prn dosing Need liver failure >80% for accumulation of

drug Renal impairment increases plasma

concentrations of active metabolites (MS, demerol; not fentanyl)

Opioid Problems

Ongoing use activates glial cells Release neuroexcititory signals Release pro inflammatory signals

Oppose analgesia Enhance tolerance Enhance Resp depression Enhance dependence Promote development of (and maintanace)

pathologic pain pathways Via non-opiod receptors

Adjuvant Rx

Anticonvulsants Action is to suppress spontaneous neural discharge

in damaged/overactive neurons Especially useful in neuropathic pain, acute and

chronic Slow onset Long half-life Side effects (Gabapentin)

Sleepiness/dizziness Allergic reactions Withdrawal precipitated seizure Suicidal thoughts Pregnancy Class C

Adjuvant Rx

Antidepressants Action is to block presynaptic reuptake of

serotonin and/or norepi Potentiates benefits of opioids Help normalize sleep Side effects

Antimuscarinic (dry mouth, urinary retention) Antihistamine (sedation, increased gastric pH) Alfa-adrenergic blockade (orthostatic

hypotension) Suicidal thoughts

Adjuvant Rx

COX inhibitors (NSAIDS, ASA, Tylenol) Action is prostaglandin inhibition Benefits

Analgesia Antipyretic Anti-inflammatory Enhances opioid effects

Side Effects GI upset/ulcers Platelet inhibition Bronchospasm (potential) Renal dysfunction

Adjuvant Rx

COX-2 selective inhibitors (Celebrex) No platelet inhibition Decreased upper GI side effects 12-24 hr duration Analgesia equal in non-selective COX

inhibitors

Acute pain management in patients on chronic pain regimens

Key is identifying chronic pain regimen Home medicine history (dosing, frequency,

duration) Family assistance Tox screen

Social history

Acute pain management in patients on chronic pain regimens

HOME MEDS

Acute pain management

Goal is adequate therapy with minimal side effects

PCA advantages Cost effective Safe (when used correctly) Superior analgesia High patient satisfaction

Acute pain management

PCA cont Basal rate

Controversial May avoid breakthrough May increase Resp Depression 30-50% of total dose may be via BR

Useful for adding in home dose

Acute pain management

Physical dependence Occurs in all patients on large doses of opioids

for prolonged periods Dependence does not equal addiction

Acute pain management

Avoiding withdrawal: alpha2 agonists (Clonidine) Acts postsynaptically to decrease

norepi/sympathetic outflow presynaptically Decreased SVR/BP Negative Chronotrope Analgesia Sedation Anxiolysis Prolonged duration of peripheral nerve blocks

Available PO, transdermal, parenteral

Acute pain management

Clonidine side effects Bradycardia Hypotension Sedation Dry mouth

Acute pain/trauma and regional anesthesia techniques

Advantages of regional anesthesia Better pain control Better preserved pulmonary function Early ambulation Early PT Decreased M&M

Risks: Local anesthetic toxicity Damage to nerve/other structures

PERCUTANEOUS CONTINUOUS NERVE BLOCK FOR TREATMENT OF PAIN IN

CHEST WALL TRAUMA

Background

Trauma is a leading cause of death and disability

Thoracic trauma accounts for 10 to 15% of trauma admissions

25% of annual traumatic deaths result from chest trauma

Rib fractures are the most common injury associated with chest trauma.

Trauma associated with rib fractures results in significant morbidity and mortality

The Morbidity and Mortality of Rib Fractures

7147 trauma patients reviewed Level 1 Trauma Center

10% had rib fractures

Only 6% of patients had isolated rib fractures, 94% had associated injuries 32% had HTX/PTX 26% had Lung Contusion

Ziegler, D.. The morbidity and mortality of Rib Fractures.The Journal of Trauma, 1994.

Conclude that rib fractures are a marker of severe injury Mortality rate of 12%, with most deaths (69%)

occurring within first 24 hours 55% patients required immediate operation or ICU

admission 35% patients required ECF upon discharge 35% developed pulmonary complications, 6% of

these patients died A lower ISS in elderly that died compared to

younger patients, suggests it takes a lesser injury to be lethal in elderly

Increased severity of injury and mortality with increasing number of rib fracturesZiegler, D.. The morbidity and mortality of Rib Fractures.The Journal of

Trauma, 1994.

Perils of rib fractures

Retrospective analysis at Level 1 trauma center

Identified High-Risk rib fractures to be those associated with intrathoracic injury, increased morbidity and mortality

Factors indicating a high-risk rib fracture include High energy trauma Extremes of age > 3 rib fractures Associated injuries

Perils of rib fractures. Sharma OP, Oswanski MF, Jolly S, Lauer SK, Dressel R, Stombaugh HA American Surgeon, 2008

Elderly Trauma Patients with Rib Fractures Are at Greater Risk of Death and Pneumonia

The population 65 years of age and older currently represents approximately 12% of the population in the United States

The most common mechanism for rib fractures are motor vehicle crashes

Low velocity falls increase with increasing age Trauma patients older than 65 are more likely

to die or have significant complications after chest trauma than similarly injured younger patients Bergeron, E et al. Elderly Trauma Patients with Rib Fractures Are at greater risk

of Death and Pneumonia. J of Trauma. 54:3, 478-484. March 2003.

Elderly Trauma Patients with Rib Fractures Are at Greater Risk of Death and Pneumonia

Also found that severity of trauma morbidity and mortality increase with increasing number of rib fractures

Background

The pain associated with rib fractures leads to: respiratory compromise impairment of pulmonary mechanics

including: hypoventilation atelectasis decreased pulmonary compliance poor pulmonary drainage hypoxia

This can be further complicated by pre-existing lung disease, underlying pulmonary contusion and development of pneumonia

Background

Flail Chest 70% long term dyspnea 49% had persistent chest wall pain

Landercasper JL, Cogbill TH, Lindesmith LA: Long-term Disability after Flail Chest Injury.J trauma. 24:410-14, 1984

Paradoxical chest movement

Goals of Treatment

1. Pain Control

2. Pulmonary Toilet

3. Management of

associated Injuries

Methods of pain control

Pain management is critical in these patients

Despite multiple approaches to pain control

including: anti-inflammatory medications systemic narcotics intrapleural blocks intercostal nerve blocks epidurals

There is no single method satisfactory to all patients.

Think MULTIMODAL

Medline search 1966-2002 Summarized the various analgesic

techniques used in patients with multiple fractured ribs

No single method that can be safely and effectively used for analgesia in all circumstances.

Acute Pain Management of Patients with Multiple Fractured Ribs

Karmakar, M, et al. 54:3. 615-625. March 2003

Opioids/Narcotics

PROS Systemic opioids

are readily available and are minimally invasive.

CONS Respiratory

Depression Sedation Constipation Hypotension Nausea/Vomiting Urticaria/Pruritus

Epidural Catheter

PROS May be the gold

standard for analgesia in rib fractures allowing treatment of multiple levels as well as bilateral fractures.

No CNS depression Prolonger duration

CONS Hypotension Urinary Retention Altered Neuro exam Avoid anticoagulation Risk of

Infection Epidural hematoma Spinal cord injury (rare)

Intercostal Nerve Block

PROS Highly effective

for 8-24 hours No CNS

depression

CONS Require multiple

injections at multiple levels

Risk of Pneumothorax Risk of toxicity Risk of vascular

puncture and injection

Short duration

Intercostal Nerve Block

ON-Q

PROS Effective for

multiple rib fractures, bilateral

No CNS depression

No altered neuro exam

Can be discharged home/rehab

Anticoagulation OK

CONS Risks of systemic

toxicity with local Pneumothorax Hematoma

CATHETERS

Trauma-Rib Fx

Trauma-Rib Fx

Trauma-Rib Fx

What’s important

Good prep of the area Pain score not revealing in multiple trauma

patients Incentive spirometry-focus specifically on

the pain associated with deep breathing reduce the incidence of pneumonia often seen

in multi-level rib fracture patients

Clinical Experience Reviewed patients who received an ON-Q

Catheter system from July 2005-Feb 2008 41 trauma patients with ON-Q placement

identified Age range 18-88 years

average age 61 years old Mean # rib fx 7.61 VAS pre insertion 9.4 VAS post insertion 4.8

p<0.001

Halm, Shapira Presented ACS Annual Meeting 2008

Summary

In the absence of a universal modality for the management of pain associated with rib fractures, the “over the ribs” ON-Q catheter pain system provides a safe and effective method for pain relief in the injured patient with rib fractures.

It enables minimization of opiates utilization, early ambulation and effective pulmonary toilet.

Patients can continue treatment after discharge from hospital.

The placement is a simple bedside technique and does not require a specialized practitioner for placement.

Associated TraumaSternal fracture

Bilateral parasternal insertion

Other Opportunity

FEMUR FRACTURE

PUMP INSERTION IN FEMUR-deep

PUMP INSERTION IN FEMUR-superficial

ACETABULUM FRACTURE

ACETABULUM FRACTURE

Fascia Iliaca Block

Goal: Block the femoral and lateral femoral cutaneous nerves, ideally with proximal spread into the lumbosacral plexus

Technique: Ultra sound guidance Medial to ASIC and sartorius muscle, lateral to

fascia over psoas and femoral nerve/artery Just deep to fascia iliaca 30-40mL dilute local anes (0.2% ropivacaine) Single shot vs catheter infusion

Conclusion Pathophysiology of pain

Complex interneural interactions Opioids

Mainstay of Rx PCA safe and effective

Adjuvant meds Improve pain control Help avoid opioid side effects

Acute on chronic pain Requires multimodal approach

Regional Anesthetic techniques Improve outcomes and patient satisfaction