Week 13 Notes - Injuries pt. 2.pdf

Mechanical Injury Causes of Deaths from Trauma- approximately 160,000/year  Motor vehicle accident- 44,000  Firearms- 30,000 (55% suicide, 40% homicide, 5% accidental or law enforcement related)  Acute toxic exposure- 26,000  Falls- 17,000  Suffocation including drowning-...

Mechanical Injury Causes of Deaths from Trauma- approximately 160,000/year  Motor vehicle accident- 44,000  Firearms- 30,000 (55% suicide, 40% homicide, 5% accidental or law enforcement related)  Acute toxic exposure- 26,000  Falls- 17,000  Suffocation including drowning- 13,000  All other -31,000 Types of injuries  Abrasion: scraping the skin surface →damage to superficial layer of skin  Contusion or bruise: blunt force → hemorrhages under intact skin  Laceration and incision: Tearing (blunt force) and cutting (sharp object)  Avulsions and fracture: tendon insertions and bones  Extended compression → ulcers  Gravity alteration → accelerated aging Mechanical energy (E)  transferred into the tissue due to action of forces (F) or force fields, causing displacement (x) and change in velocity (v)  E= F x = mv2/2 Pressure ulcer  Ischemia with compression or shear forces  1→4 stages, depending on depth  Preceding stage 1 are changes significant for DC: o sensation, o temperature, o tissue firmness  early detection possible based on: subepidermal micro-edema, micro-vascularisation, micro-hemorrhages: o high-frequency ultrasound o Thermography IR with adjacent skin comparison o Spectroscopy (Hb) o Skin electric conductance (most reliable)  Scafi et all. Bedside Technologies to Enhance the Early Detection of Pressure Injuries. A Systematic Review. J Wound Ostomy Continence Nurs. 2020;47(2):128-136. Abnormal gravity effects  Microgravity in space flight → accelerated aging documented on: musculoskeletal, cardiovascular, respirator, neurologic, blood and CSF redistribution, metabolic, endocrine, eyes; mostly reversible with appropriate intervention after returning to Earth gravity Dr M Hossu Notes 192  Electrical Injuries o Causes- Electrocution and lightning strike. o Physics of electrical injuries o Current flows in a closed circuit from high energy to low energy of electrical charges o The amount of current (I) is related to the following factors I = V/R  Voltage exposed to  Resistance of the body tissues and of skin at the point of entry and exit  Available moving electrical charges (electrons and ions) o Severity of tissue damage is dependent on the amount of energy transferred into the tissue: E= I2Rt = VIt =V2t/R o The electrical resistance of the tissues (R) o Exact path taken through the body o Duration of exposure to the current (t) o Type of current  Effects of AC current  Effects of DC current o Two major effects o Passage of current producing heat – happens in any tissue or object o Interfering with the function of electrical tissues: alteration of electrons and ions flow across membranes  Muscles – spasm, mostly for AC  Cardiac conduction tissue → ventricular fibrilla on  Depression of respiratory centers o [mn] Low energy electric and electromagnetic fields or radiation may not be life threatening but still pathological:  alteration of electrons and ions flow across membranes = classical view of electric current effects  alteration of voltage gated ion channels  most sensitive appears to be voltage gated calcium channel (VGCC) – multiple effects due to increased intracellular Ca o Electric (and magnetic) fields can also be beneficial by restoring electromagnetic “homeostasis”: muscle rehab, tissue growth and repair o It can also reset activity of electrical dependant tissue: e.g. defibrillator in cardiac arrest Dr M Hossu Notes 193  Ionizing Radiation Injury A. Sources of exposure 1. Natural radiation (cosmic, earth, inside living organisms) 2. Nuclear bombs 3. Nuclear reactor 4. Diagnostic and therapeutic purposes B. Radiation terminology  rad- is a measure of the energy absorbed per unit mass of the tissue. 1 rad is an absorbed dose of 100 ergs per gram of tissue  Gray- is the SI unit that replaced the rad. 1 Gy = 1J/kg = 100 rads  Roentogen (R) is a unit of unit radiation exposure. For Xray, 1R ~ 1 rad  Sievert (Si) and rem (radiation equivalent man). The dose of any type of radiation that has the same biologic effect in humans as 1R of x-rays or gamma rays = biological equivalent dose o BED (in Si) = D (in Gy) x Q (“quality” factor)  Q = how effective is radiation in damaging tissue compared with X-ray or high energy electrons C. Types of ionizing radiation Dr M Hossu Notes 194  Mechanism of Radiation Injury  Direct action- changes molecules in the cells themselves o “Direct hit”: Membrane, DNA  Indirect action- causes formation of free radicals o damage the cells and especially rapid dividing o bone marrow, epithelial, endothelial cells Effects of radiation injury o Cellular injury, necrosis, or apoptosis  cytoplasmic swelling,  mitochondrial distortion,  Degeneration of the endoplasmic reticulum.  Plasma membrane breaks / focal defects may be seen  Chromosomal and nuclear changes o Mostly fibrosis, like after chronic inflammation o Vascular anomalies, with fibrosis, collagenous hyalinization, thickening of the intima, thrombosis, scaring o Neurological effects: shown in exposure to cosmic radiation and radiotherapy o Production of cancer in irradiated cell o Production of congenital abnormalities in germ cell line  Factors that influence the severity of tissue damage o Dose o Penetration of tissues o Sensitivity of tissues o Duration of exposure  Effects of total body irradiation Dr M Hossu Notes 195  Nonionizing radiation The energy of nonionizing radiation such as UV and infrared light, microwave, and sound waves, can move atoms in a molecule or cause them to vibrate, is not sufficient to displace bound electrons from atoms but it can alter “free” moving ions and electrons (ion channels and ETS) Cells have mechanosensitive and electrosensitive structure interconnected to all cellular functions so disruption of electric and mechanical homeostasis needs to be investigated [mn] Ultraviolet radiation A. Sun burn B. Accelerated aging of the skin C. Skin cancer 1. Basal cell carcinoma 2. Squamous cell carcinoma 3. Malignant melanoma D. Signs that a mole may be turning in to a malignant melanoma A. Asymmetry B. Border C. Color D. Diameter E. Evolution Visible, Infrared, Microwave and Radio:  Classified as a category 2B agent = potentially carcinogenic by International Agency for Research on Cancer (IARC)--Agenda of World Health Organization (WHO) https://pubmed.ncbi.nlm.nih.gov/27012122/  Pall ML. Low Intensity Electromagnetic Fields Act via Voltage-Gated Calcium Channel (VGCC) Activation to Cause Very Early Onset Alzheimer's Disease: 18 Distinct Types of Evidence. Curr Alzheimer Res. 2022;19(2):119-132. https://pubmed.ncbi.nlm.nih.gov/35114921/ Dr M Hossu Notes 196