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INVASIVE METHODS 1. Mechanical and chemical. 1. Rotary and elevator instruments. Are widely used in surgery and stomatology (scalpels, tweezers, peans). 2. Water scalpel. cut s tissues by narrow water torrent ( isotonic solution of NaCl) device consists of: pressure

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1. Mechanical and chemical

1. Rotary and elevator instruments

Are widely used in surgery and stomatology (scalpels, tweezers, peans)

2. Water scalpel

  • cuts tissues by narrow water
  • torrent (isotonic solution of
  • NaCl)
  • device consists of: pressure
  • pump, high pressure hose
  • and water engine
  • cuts are smooth

Instruments used in stomatology


3. Cryocauthery instruments

Are used for deep freezing of tissues (from 25°C to -190°C) – liquid N2 is used.If the cooling is slow , than water mole-cules change into the ice crystals and these may damage the cells during rewarming.

Advantage: anaesthetic effect of cold, small destructionof the tissue,no bleeding

Using: ophthalmology, gynecology, urology, oncology


2. Ultrasound Methods

  • ultrasound (US) with high intensity (50 – 1000 W/cm2)
  • selective destruction of tissues

High frequency focusing US

(1 – 3 MHz)

Low frequency US (20 – 50 kHz)

Ultrasound is produced bypiezo-

electric crystal and conducted by special wave- conducting system, that amlifies the amplitude by 10 times. US scalpel oscilates in re-sonance with transformer´s fre-quency. It is widely used in oto-laryngology and neurosurgery.



This device is utilised for extrac-tionof cloudy lense (cataract). Method is based on low frequency ultrasound application, which destructs the cloudy lense.Lense is then coagulated and sucked off.

3. Electrical Methods

extraction of cloudy lense

Electrotomy and electrocoagulation

  • use effect of HF electric currents> 100 KHz
  • production of heat by contact of different electrode
  • with tissue - water is evaporated and cells are dest-
  • ructed. This results in tissue coagulation andclos-
  • ng of vessels – cuts do not bleed
4 methods of vital organ support
4. Methods of vital organ support

1. Breathing support – artificial respiration

  • is used when no spontaneous respi-
  • ration is present apnoe, or by pulmo-
  • nary insufficiency- partial presure of
  • oxygen in arterial blood is < 5kPa,
  • pressure controled ventilators-switch inspirationto expiration by setting of pressure of inhaled air
  • volume controled ventilators-can set inspiratory volume of breathing and
  • ts frequency - optimal value of pulmo-
  • nary ventilation

Parameters which can by set up on the ventilator:

  • respiratory exchange ratio (1:1.5 or 1:2)
  • respiratory frequency (8 – 24 /min)
  • inspiratory oxygen concentration (20 – 100%)
  • inspiratory pressure (maximal value is 7 kPa)
  • postinspiration time (between end of inspiration
  • and start of expiration)control of PaO2 (by
  • oxymetry) and PaCO2(by capnogram)

Special type: CPAP (continuous positive airway pressure)


2. Substitution of Heart function –Extracorporal


Blood pump – elastic tube and rotor with 2 sheaves – they rotate, compress the tube and drive the blood before them Amount and pressure of blood is regulated by turning the pump rotation

Oxygenator– substitutes the lung function, blood is eliminated from from CO2 and is saturated by O2

Warmer device – modifies the temperature of oxygenated blood which returnes to the body to 37.5 °C


2.Heart substitutions

  • transplatantion of human´s heart
  • implantation of artificial heart dri-
  • ving of pump is provided by pressure
  • ofcompressed air, suitable non-iritable
  • material is used (imunology)
  • surgery substitution of coronary ar-
  • teries (bypass) and heart valves (be-
  • cause of stenosis or insufficiency)
  • PACEMAKING – uses DC current
  • to treat the „sick sinussyndrom“
  • therapy

artificial heart



3. Artificial kidney - hemodialysis

Enables to treat the intoxications or disorder affecting the function of kidney– filtration, resorbtion

  • Basic parts of this device:
  • Extracorporeal blood circulation- see the previous chapter
  • Dialysing circulation – circle which provides flow and preparationof dialysing solution – by mixing water and NaHCO3,pH is changed to 7.36 and osmolarity to 5300 mOsm/l (as in bloodplasma). Integrity of dialysing membrane is controled by detection of hemoglobine amount. Temperature of dialysing solution is kept on the same value.

Dialyser – is divided into 2 parts (blood part and dialy-sing part) bydialysing membrane.

  • Blood flows by laminary streaming (200 – 300 ml/min) on the one side of the membrane and passes the dialysing membrane.
  • Dialysing solutionflows in opposit direction by turbulent streaming (500ml/min) on the other side of the membrane.
  • It results in increasing of concentration gradient, which leads to rapid diffusionof low weight molecules-toxic substances (urea, aceton) fromblood to dialysing solution. Velocity of ultrafiltration and amount of redundant water can be regulated by transmembrane pressure
  • .

3. Artificial kidney-scheme of hemodialysis and peritoneal dialysis

Peritoneal dialysis– peritoneum works as a filter for hemo-perfusion, hemofiltration ( intoxication treatment and liver failure disorders)

Hemodialysis Peritoneal dialysis


4. Artificial lenses

are implanted because of eye injuries or the cataract

Composition of lens:

  • optic part – increases refractive power of the eye
  • haptic part – for mechanical fixation in the eye ball
  • Types:
  • solid and hard (polyme-
  • tacrylate)
  • soft ( hydrogels)

5. Cochlear electrode implants

for deaf patients whose conduction of APsthrough the acoustic nerve retained intact

  • Multiple electrode stimulating sys-
  • tem consists of 2 parts:
  • External part
  • sound processor
  • sensitive microphoneamplifier
  • transmitter
  • Internal part
  • receiver implanted under the skin
  • electrode system-is inserted into Scala media of theCochlea near to basilar membrane in the vicini-ty of the acustic nerve

6. Prothesis of limbs

  • Mechanical prothesis – mobile only in knee and ankle, enable walking with assistance (lower extremities) or partial grip function
  • Bioprothesis – biosignals conducted by needle electro-des into preserved muscles. There is a lack feedback between afferent and efferent signals. Mechanism of unit can be electric and hydraulic.
  • Biomanipulator – bioprothesis of new generation – more complicated functions with feedback from sensors
  • Endoprothesis– artificial joints being made from
  • special steel (knee, hip joint)

7. Injection pumps

  • enable to assure an exact timetable for drug´s application into the blood circulation
  • to speed a dose, quantify it and apply a solution, its time of application, all functions can be seen on display
  • operation of the pump is controlled by PC microprocessor, with ability to choose the mode

Trombolytic pumps

Drug(which dissolve the thrombus or prevents its formation) is applied into the blood by a pulse of compressed air

Insulin pumps

Automatic programmable insu-lin applicator device with auto-matic control of sugar level in blood

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