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Representation of Pain in the Brain

SUMMARY Nociceptive information is transmitted from the spinal cord to the brain via several different pathways. Consequently, multiple regions of the brain are activated during the complex experience of pain. Cortical regions activated during pain include the limbic, paralimbic, and sensory areas, notably the anterior cingulate cortex, insular cortex, prefrontal cortex, and primary and secondary somatosensory cortices. Furthermore, brain areas are involved in both opiate and…

Spinal Cord Plasticity and Pain

SUMMARY Clinically relevant forms of pain cannot be fully understood without appreciating the various forms of plasticity that develop in the spinal dorsal horn after injury or with disease. All major components of the spinal cord nociceptive network are subject to potential short- and long-term plasticity. This applies in particular to the synaptic contacts between nociceptive nerve fibers and spinal dorsal horn neurons. Synaptic strength is…

Neuroanatomical Substrates of Spinal Nociception

SUMMARY The spinal dorsal horn receives input from a wide variety of primary afferent axons, including nociceptors , which respond to tissue-damaging stimuli from the skin, muscles, joints, and viscera. The patterns of termination of primary afferents within the spinal cord are related to axonal diameter and receptive field modality. Most nociceptive primary afferents have slowly conducting fine myelinated or unmyelinated axons , and they terminate…

Microglia: Critical Mediators of Pain Hypersensitivity after Peripheral Nerve Injury

SUMMARY Neuron–glial interactions are increasingly recognized as being key for physiological and pathological processes in the central nervous system. Microglia in the spinal dorsal horn respond to injury to peripheral nerves by adopting a specific response state characterized by up-regulation of the purinergic receptor P2X 4 . In this P2X4R + state, microglia release brain-derived neurotrophic factor, which disinhibits neurons in the spinal nociceptive processing network.…

Inflammatory Mediators and Modulators of Pain

SUMMARY Disease and injury frequently result in pain and hyperalgesia. These abnormal sensory events arise in part from the action of inflammatory mediators on the peripheral terminals of nociceptive neurons. In this chapter we begin by reviewing the different ways in which such mediators bring about the activation or sensitization of nociceptive terminals. We then consider the biological effects and potential importance of different inflammatory mediators.…

Molecular Biology of Sensory Transduction

SUMMARY The perception of pain arising from a noxious stimulus starts with conversion of the energy of the stimulus into an electrical signal in the primary afferent neurons innervating the site of the stimulus. This process of energy conversion is called transduction. The three general modalities of noxious stimuli that impinge on the body are chemical, thermal, and mechanical, although each of these groups can be…

Peripheral Mechanisms of Cutaneous Nociception

SUMMARY Nociceptors are a specialized class of primary afferents that respond to intense, noxious stimuli. Unmyelinated nociceptors signal the burning pain from intense heat stimuli applied to the glabrous skin of the hand, as well as the pain from sustained pressure. Myelinated nociceptors signal the sharp pain from heat stimuli applied to hairy skin and from sharp mechanical stimuli. Both myelinated and unmyelinated nociceptors signal pain…

Extracorporeal membrane oxygenation cannulation

Specialty and category within specialty Critical care medicine Mechanical support for refractory respiratory and cardiac failure Before procedure Indications Venovenous extracorporeal membrane oxygenation (ECMO) Acute severe respiratory failure with high mortality risk, reversible and nonresponsive to optimal conventional therapy. ECMO is considered when there is approximately at 50% mortality (PaO 2 /FiO 2 <150 on FiO 2 <90% and Murray score 2–3) and indicated at 80%…

Indirect calorimetry

Before the procedure Indications A need for estimating energy expenditure (EE) in critically ill patients in whom the EE is highly variable and difficult to predict by simple equations, such as: Patients with liver disease Obese patients Trauma patients Patients with comorbidities Patients under sedation Contraindications You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you…

Intracranial pressure monitoring

Before procedure Indications Common Traumatic brain injury (TBI) Subarachnoid hemorrhage Intracranial hemorrhage (ICH) Hydrocephalus Uncommon Meningitis/encephalitis/brain abscess Acute liver failure Pseudotumor cerebri Postoperative Contraindications Absolute Anticoagulation Bleeding diathesis Relative Scalp infection Lack of specialized healthcare personnel You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here

Jugular venous and brain tissue oxygen tension monitoring

Ultrasound-guided internal jugular vein oxygen saturation (SjvO 2 ) catheter placement: Before the procedure Indications Severe traumatic brain injury Subarachnoid hemorrhage During neurosurgical and cardiovascular procedures in which cerebral blood flow may be reduced Detection of arteriovenous fistulas To titrate hyperventilation in patients with increased intracranial pressure (ICP) Contraindications Absolute Infection of the placement site Suspected pathologic conditions affecting the internal jugular vein or superior vena…

Lumbar puncture

Before procedure Indications Suspicion of a central nervous system (CNS) infection Suspicion of a subarachnoid hemorrhage The need to obtain cerebrospinal fluid to diagnose other inflammatory or degenerative CNS diseases Reduction of cerebrospinal fluid (CSF) pressure in pseudotumor cerebri Contraindications Absolute Intracranial or spinous (especially intramedullary) mass (e.g., tumor, abscess). If there is a concern, an imaging study should be performed before the procedure. A rapid…

Nasoenteric feeding tube insertion

Before procedure Indications Inability to maintain volitional intake (in the setting of a functional gastrointestinal tract) and : Critical illness expected to require an intensive care unit (ICU) stay of more than 2 days Poor nutritional status Weight loss and nutrient depletion Multiple comorbid conditions Failure to eat for more than 7 days Contraindications Inability to tolerate enteral nutrition: Mechanical bowel obstruction Peritonitis Hemodynamic compromise (e.g.,…

Esophageal balloon tamponade

Before procedure Indications Short-term hemostasis and stabilization of patients until definitive therapy can be arranged Failure to achieve hemostasis after endoscopic treatment of bleeding esophageal varices As a temporizing measure when endoscopic treatment is not immediately available or emergency transcutaneous intrahepatic portosystemic shunt is being arranged Contraindications Known or suspected esophageal tear Recent esophageal surgery Known esophageal stricture Use with caution with those patients with a…

Percutaneous dilatational tracheostomy

Before the procedure Indications Requirement of a temporary or long-term artificial airway for prolonged mechanical ventilation Management of secretions Nonemergency airway obstruction Contraindications Inability to clearly palpate and identify tracheal landmarks Enlarged thyroid or other neck mass Active infection at the site Emergency need for airway High ventilatory requirements (FiO 2 ≥70%, positive end-expiratory pressure [PEEP] greater than 15 cm H 2 O) Bleeding Increased intracranial…

Bronchoalveolar lavage and protected specimen bronchial brushing

Before the procedure Indications Diagnosis of pneumonia Viral, bacterial, fungal, pneumonias Quantitative cultures for ventilator-associated pneumonias Infiltrates in an immunocompromised host Evaluation of diffuse lung infiltrates and evaluation of interstitial lung disease Suspected pulmonary hemorrhage Suspected malignancies Both bronchoalveolar lavage (BAL) and protected specimen bronchial brushing (PSB) use quantitative culture techniques to differentiate between airway colonization and true pulmonary infections. Contraindications Acute respiratory distress syndrome with…

Flexible bronchoscopy

Specialty and category within specialty Intensive care medicine: Diseases of the respiratory system Airway management CPT codes Bronchoscopy ICD-9 codes 33.2 Diagnostic procedures on lung and bronchus 33.22 Fiber-optic bronchoscopy 33.24 Closed [endoscopic] biopsy of bronchus 33.27 Closed endoscopic biopsy of lung Preprocedure You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member.…

Chest tube placement, care, and removal

Before the procedure Indications Most commonly undertaken to treat one of the following conditions: Pneumothorax Pleural fluid collection Hemothorax Simple effusion Empyema Can be both a diagnostic and a therapeutic maneuver Contraindications In an emergent situation (i.e., tension pneumothorax), there are no contraindications In a nonurgent situation, caution should be exercised in the presence of: Known or suspected adhesions Prior chest surgery or trauma History of…

Thoracentesis

Before the procedure Indications Pleural effusion is not explained by the clinical presentation Massive pleural effusion with impending respiratory failure Suspected pleural space infection Suspected complication of pneumonia (empyema) Suspected hemothorax Contraindications Absolute Lack of expertise Severe uncorrectable coagulopathy (platelet count <25,000 cells/μL; international normalized ratio [INR] >2.0) Azotemia (creatinine >6 mg/dL) Uncooperative patient Relative Operator-dependent and of technical nature Lack of image guidance to determine…

Paracentesis and diagnostic peritoneal lavage

Paracentesis: Before the procedure Indications Paracentesis is the insertion of a needle or catheter into the peritoneal cavity for the purpose of aspirating peritoneal fluid. It is most often indicated for diagnostic or therapeutic evacuation of ascites. Diagnostic indications New-onset ascites: fluid evaluation to help determine etiology, differentiate transudate versus exudate, detect the presence of cancerous cells, or address other considerations Differentiate between suspected spontaneous or…