Contraindications for TUS

Question 1

What is deep vein thrombosis?

Answer 1

A blood clot that develops within a deep vein, usually in the leg

Question 2

Is DVT a global or local contraindication?

Answer 2

Global

Question 3

What can happen if you use TUS on someone with DVT?

Answer 3

• Ultrasound could dislodge or cause partial disintegration of a thrombus, potentially blocking circulation to vital organs
• Could travel to a vital organ eg lungs (causing pulmonary embolism) or brain (stroke/ cerebral embolism)
• Mechanisms by which this may occur include disintegration of existing blood clots induced by mechanical effects of ultrasound and possible increased local blood flow
• Some evidence showing ultrasound causing partial disintegration of a thrombus but studies on local blood flow produced inconsistent and inconclusive findings

Question 4

What is a varicose vein?

Answer 4

In a healthy vein, blood is prevented from flowing backwards by a series of tiny valves that open and close to let blood through. If valves weaken or are damaged, the blood can flow backwards and collect in the vein, eventually causing it to be swollen and enlarged

Question 5

Is acute inflammation a local or global contraindication?

Answer 5

Precaution rather than contraindication

Question 6

What might happen if you use TUS on acute inflammation?

Answer 6

• Activates cellular processes of inflammation, without heating and without increasing swelling, to promote faster resolution of the inflammatory phase of healing
• Has been used in several clinical studies to treat acute injuries; no adverse reactions have reported
• You would use high ratio duty cycle

Question 7

What is myositis ossificans?

Answer 7

Calcification within muscle – is a complication following muscle contusion. Body lays down more calcium if an area is subject to blunt trauma, especially repeatedly

Contusion = a region of injured tissue or skin in which blood capillaries have been ruptured

Question 8

Is myositis ossificans a local or global contraindication?

Answer 8

Local

Question 9

What might happen if you use TUS over myositis ossificans?

Answer 9

Ultrasound stimulates osteoblast function and has been shown to promote repair of bone fractures

With myositis ossificans bone is being laid down in soft tissue so you don’t want to risk making it worse

Question 10

What are boils and folliculitis?

Answer 10

Bacterial infections. Boil – hard painful lump that fills with pus. Folliculitis – infection and inflammation of one or more hair follicles

Question 11

Are boils and folliculitis local or global contraindications?

Answer 11

Local - keep area covered

Question 12

What might happen if you use TUS over boils and folliculitis?

Answer 12

The effect of ultrasound on bacterial growth is unknown. But we don’t want to inadvertently spread it

Question 13

Is cancer/ malignancy/ tumour local or global?

Answer 13

Global

Question 14

What could happen if you use TUS on someone with malignancy?

Answer 14

• Soundwaves applied to tumour cells may stimulate growth and induce new blood-vessel growth, which may help provide fuel for further tumour growth and potentially promotes metastases
• There is inconsistent evidence about whether ultrasound increases tumour growth and metastases in animal models. So could possibly argue that this is a local contra.
• If we consider the cost benefit analysis of using something that could potentially make a cancer spread to treat a musculoskeletal injury I would always err on side of caution and treat as global

Question 15

Is pregnancy a local or global contra?

Answer 15

Local to low back and abdomen

Question 16

What might happen using TUS during pregnancy?

Answer 16

• Sound waves transmit through amniotic fluid and could cause foetal malformations including growth retardation and neural tube defects
• Risks are greater if tissue heating occurs or if maternal core temperature is elevated
• TUS has produced malformations in foetal tissue models
• most studies are on mice, who are obviously much smaller - would waves reach a human foetus? But not worth it in a cost/ benefit analysis

Question 17

What might happen using TUS with a pacemaker?

Answer 17

• Local contra
• TUS should be used only when the exact location of device components is known
• Soundwaves reflected at a device–tissue interface could possibly cause tissue heating and uneven cavitation / hot spots
• Effect of therapeutic ultrasound waves on function of pacemakers and electronic stimulators is not known
• Safety alerts about serious injury or death exist in relation to pacemaker patients receiving ultrasound diathermy; but this is different to that used by sport therapists

Question 18

What might happen using TUS over active epiphysis?

Answer 18

• Local contra
• Relates to active bone growth plates (so aged <21)
• Ultrasound may alter bone growth
• About 75% of ultrasound energy is reflected at tissue/bone interfaces, and the transmitted portion is largely absorbed by periosteum. Intensities that could produce unwanted bone growth are likely to cause pain as a result of the periosteal absorption
• So if we avoid this area and keep checking for pain should be ok

Question 19

What might happen using TUS over metal implants?

Answer 19

• Local contra
• Metal reflects about 90% of incident ultrasound—slightly more than is reflected by bone
• Evidence shows that metal is not heated by ultrasound, and sound waves do not loosen screws or plates
• Application requires precautions to avoid standing waves and unstable cavitation

Question 20

What might happen using TUS over plastic/ cement implants?

Answer 20

• Local contra
• should be avoided directly over cement or plastic joint replacements or prostheses
• has been shown to alter the mechanical properties of plastic and cement components of surgical implants in animal models

Question 21

What might happen using TUS over local circulatory insufficiency?

Answer 21

• local contra
• Adequate circulation is required to dissipate heat produced by TUS
• If heat cannot be dissipated could lead to further ischemia, pain, and possibly blister formation

Question 22

What might happen using TUS over devitalised or impaired tissues?

Answer 22

• local contra
• body areas with impaired pain or heat sensation would mean patients cannot provide appropriate and timely feedback
• TUS without patient feedback is associated with a significant risk of burns or unstable cavitation, both of which can result in significant tissue damage
• Perform a sensory discrimination test to minimise risk of this

Question 23

What might happen using TUS over bleeding?

Answer 23

• Local contra
• Mechanical vibration produced by ultrasound can disrupt platelet plug formation and cause uncontrolled bleeding into surrounding tissues

Question 24

What might happen using TUS over a skin disease?

Answer 24

• local contra
• Transducer contact may further irritate or traumatize at-risk skin
• TUS using a water bath is a safe alternative method of application to avoid physical trauma to skin
• Ultrasound has been applied using water-immersion method to chronic venous leg ulcers without adverse reactions

Question 25

What might happen using TUS over eyes?

Answer 25

• local contra
• Unstable cavitation could occur in ocular fluid as a result of standing wave formation, leading to retinal damage
• Little actual evidence for this

Question 26

What might happen using TUS over reproductive organs?

Answer 26

• local contra
• Ultrasound may contribute to infertility by affecting gamete production, especially heat-sensitive spermatogenesis in the testes
• Little actual evidence for this

Question 27

What might happen using TUS over anterior neck?

Answer 27

• local contra
• trying to avoid carotid sinus
• carotid sinus is our major baroreception (blood pressure monitoring) site
• effects of ultrasound on these excitable tissues are unknown