Distension media in hysteroscopy

DISTENSION MEDIA IN HYSTEROSCOPY

Dr Mandeep Bhandal

Uterine distention medium

Uterine cavity- a potential space

Minimum pressure - 30 mmHg to separate uterine walls

- 45-80 mmHg to expand uterine cavity,

rarely >100 mmHg

MAP ~ 100 mmHg

Uterine distention medium

Choice depends on the type of procedure

TYPES GASEOUS CO2

LIQUID

Electrolytic NS, Ringer lactate

Non-electrolytic Hyscon (32% dextran 70)

Glycine

Sorbitol

Mannitol

TYPE Operative use Office use Miscibility with blood

Complex procedure

Safety

GASEOUS

CO2

+ +++ + + ++

LIQUID Nonelectrolytic

Hyscon +++ +++ +++ ++ ++

Glycine +++ + ++ +++ +

Sorbitol +++ + ++ +++ +

Mannitol +++ + ++ +++ ++

LIQUIDElectrolytic

NS +++ + ++ +++ +++

RL +++ + ++ +++ +++

Comparison of hysteroscopic medium

+++,Highly advantageous; ++, average; +, unsatisfactory

CO2 The only gaseous medium used Yields a clear image of endometrial cavity Easy to infuse Does not clog essential instrumentation Inexpensive Readily available Well toleratedRapidly absorbed and released.Best suited for office diagnostic

hysteroscopy

Disadvantages to the use of CO2

May produce bubbling, which is cumbersome and may obscure the view.

Because CO2 gas is invisible, a leak in the system may not be noticed for some time.

A specific machine is required for electronic calibration of the CO2 flow rate and pressure.

Finally, use of a laser becomes cumbersome owing to the smoke and fumes .

Flow rate

Ideal - 40-50ml/min

Maximum - should not exceed 100ml/min

Pressure

Should not exceed more than 100 to 150 mmhg

An electronic hysterosufflator for uterine distention with CO2 gas

Precautions

Standard monitoring of the patient

Laparoscopic insufflation equipment never to be used.

Patient not to be placed in trendelenberg position

Limitations Least advantageous for operative

hysteroscopy

Foaming interaction between blood and gas makes the visibility difficult

Has a tendency to flatten the endometrium, thereby obscuring pathologic features.

Occasional reflux through the cervix in multiparous

patients

Complications

Category

Examples

MetabolicpCO2↑ ,pO2 ↓ ,Hypercarbia , metabolic acidosis

CO2or Air embolus

Respiratory collapse, cyanosis, Cardiac arrest

Mechanical Tubal rupture , diaphragmatic rupture

Pathophysiology of Air and Gas Embolism There is Incision of noncollapsed veins

and the presence of subatmospheric pressure in these vessels

↓ Causing a pressure gradient between the

point of entry of gas and the right side of the heart

↓ Entry of the gas into venous system.

Small amounts of air do not always produce

symptoms.

More than 3 mL/kg of air (intravenous) is required for significant clinical effects.

The gas transported to the lungs through the pulmonary arteries, causing –

Gas exchange disturbances Cardiac arrhythmias Pulmonary hypertension. Outflow obstruction Decreased pulmonary venous return, Decreased left ventricular preload and cardiac

output .

Paradoxical arterial gas embolism

The high pulmonary arterial pressure pushes small microbubbles through the pulmonary vasculature, which subsequently may be detected in the left atrium, causing cardiovascular problems such as coronary artery occlusion or cerebral artery occlusion.

The central nervous system may be affected similarly. Postoperative altered mental status, focal deficits, or even coma may be attributed to the cardiovascular collapse but cerebral emboli may also play a role.

These emboli may occur by a patent foramen ovale and through the a forementioned migration of emboli through the pulmonary vasculature.

Air Embolism

An air embolism is derived from room air and is, therefore, primarily composed of nitrogen and oxygen

Nitrogen is the main culprit for air embolism

Room air is introduced into the uterus-

by air bubbles in the fluid system, by means of reintroduction of the

hysteroscopic instruments that have a pistonlike effect forcing air into the uterus with each reinsertion,

by leaving the cervix and the vagina open to air when vascular injury is present.

When the patient is placed in Trendelenburg position

Signs/symptoms indicative of air/gas embolism in the different anesthetic methods

Epidural or spinal anesthesia

Chest pain

Dyspnea

Oxygen saturation ↓

Wheezing, rales

Mill wheel murmur

Detection of air/gas inthe heart byprecordial Doppler ultrasound

General anesthesia

Oxygen saturation ↓

ECG changes: bradycardia,tachycardia, prematureventricular contractions, heartblock, ST-T changes

Mill wheel murmur

Detection of air/gas in the heartby transesophageal echocardiography orprecordial Doppler ultrasound

Therapy in case of Suggested Air/Gas Embolism Rapid identification

Prevention of further gas entrainment by closing the point of air entry.

Put the patient in a reverse Trendelenburg position

The Durant maneuver- With this maneuver the patient is placed on the left side while using Trendelenburg position

100% of oxygen administered to the patient. Nitrous oxide anesthesia not to be used in cases with a high risk of air embolism.

Air retrieval using a central venous catheter, or direct needle puncture of the right heart in the case of cardiac arrest

Inotropic support /CPR

Hyperbaric oxygen therapy useful in patients with severe CNS or cardiac manifestations

Monitoring During Operating Department Hysteroscopy Standard monitoring

pulse oximetry, 3-lead electrocardiography, blood pressure measurements etCO2 monitoring standard ventilatory monitoring.

Monitoring of etCO2

A change of 2 mm Hg etCO2 or more may be a sign of embolism.

Physiologic changes such as hypovolemia, ventilatory changes, and artefacts may also result change in value.

Electrocardiographic monitoring

Early signs when large volumes of air enter the circulation

Electrocardiographic changes

Bradycardia or tachycardia, Premature ventricular contractions Heart block ST-segment depression

Other monitoring methods

Trans esophageal echocardiography

Precordial Doppler ultrasound

Conventional stethoscope

Combination of symptoms in embolism

A sudden decrease in etCO2, especially when accompanied by a decrease in blood pressure

A decrease in hemoglobin oxygen saturation

Cardiovascular collapse

Sustained hypotension not explained by hypovolemia alone

Electrocardiography changes

Prevention of complications The complication are extremely rare if the correct

insufflator is used.

The hysteroflator delivers CO2 at a rate of not more than 100ml per minute whereas the laparoflator can deliver 1-6 litres in the same time

A laparoflater should NEVER be used for hysteroscopy.

Recommendations Operating Department Personnel

Educate, raise risk awareness, and train staff.

Resuscitation protocols should be easily available.

Knowledge, maintenance, and upkeep of equipment for accurate distending medium measurement.

Safe use and maintenance of fluid management systems includes avoiding air to enter into fluid lines at any time.

Pumps should be turned off during bag changes, and fluid balance should be monitored closely.

Use a Y-connector on the fluid inflow line to reduce air entrainment during bag changes.

Recommendations SurgeonThe cervix is to be kept closed at all times.

Reintroduction of the hysteroscopic instruments should be kept at a minimum .

Air bubbles in the uterus are removed

frequently by using a continuous outflow system.

If room air or gas embolism is suspected, the surgeon should

Terminate surgery immediately, Deflate the uterus, Remove sources of fluid and gas. Cervical Os should be occluded (e.g.,

with wet gauzes).

Recommendations Anesthesiologist

Preventing air or gas embolism is of paramount importance

Nitrous oxide anesthesia, should be avoided when possible in operative hysteroscopy

Patients at high risk undergoing operative hysteroscopy should have, extensive intraoperative monitoring, specifically sensitive in recording gas emboli such as transesophageal echocardiography or precordial Doppler ultrasound.

Fluid media

The advantage of fluid over gas

A symmetric distension of uterus with fluid

Its ability to flush blood, mucus , bubbles & small tissue fragments

A pressure of 75 mm hg is usually adequate for uterine distension

Both low viscosity and high viscosity media are used

Various delivery systems

To accurately record volumes of inflow and outflow

Air should be flushed from all hysteroscopic tubings before distension

Pressure cuffs on low viscosity –fluid bags are for short procedures

Minimum pressure to be used for minimal intravasation (30-100 mm hg)

Delivery system

Syringe Gravity fed containers Hysteroscopic Pumps

A high molecular weight (MW) – 70 000 MW – in a 10% water solution.

Used for both diagnostic and operative hysteroscopy

Non electrolytic

Non conductive

Immiscible with blood

Minimally leaks through cervix and tubes (viscous)

Excellent visibility

High molecular weight fluids

Dextran

Delivery system

Administered through a 60 ml syringe

through tubing to the operative

hysteroscope Hyskon pumps were used

Fluid management system with an electronic pump for use in an office or operating suite

High molecular weight fluids Dextran

It may produce

Anaphylactic reaction, Adult onset respiratory distress

syndrome (ARDS) or Pulmonary oedema. Coagulopathies. Oliguria & Acute renal failure

Anaphylaxis can occur due to

Immediate histamine response to Dextrans

Previous sensitization to naturally occuring antigens

Cross reactivity with bacterial antigens(streptococci, pneumococci, salmonellae)

Anaphylaxis should be treated by the administration of

1. Oxygen, 2. Intravenous /intratracheal

epinephrine3. Antihistamines, 4. Glucocorticoids and 5. Intravenous fluids.

ARDS (Pathomechanism )

Use of larger volumes of fluid (> 500 ml)

Direct toxic effects on pulmonary vasculature

Expansion of plasma volume ↓ Intravascular volume overload.

Adult onset RDS requires the administration of

Diuresis Glucocorticoids Oxygen Assisted respiration Plasmapheresis

Oliguria & Acute renal failure

Inravascular absorption of dextran ↓ Increased intravascular oncotic pressure ↓ ↓ GFR ↑ Mechanical obstruction within renal nephrons and arteries ↑ Precipitation of dextran in renal tubules

Management

Diuresis Plasmapheresis

Coagulation disorders

Dextrans have antithrombotic properties

↓ platelet adhesiveness Alter fibrin clot structure ↓ Fibrinogen ↓ Clotting factors (V, VIII, IX)

Management

DiuresisPlasmapheresis

Low molecular weight fluids

Electrolyte free - 1.5%Glycine 3% Sorbitol 5 % Mannitol

Used in operative hysteroscopy using monopolar resectoscope.

.

Electrolyte containing

Normal saline Ringer’s lactate soln Used in Diagnostic hysteroscopy Operative hysteroscopy using bipolar electrode

Advantages.They can clear debris, mucus and blood

clots from the operative field and continuously wash the uterine cavity, permitting good visualization.

Should the mechanism be faulty and leakage of fluid occur, it will be immediately visible, and the fluid instilled and recovered can easily be measured.

1.5 % Glycine

Simple amino acid that is mixed in water & supplied in 3 liters bags as a 1.5% soln

Non electrolyticHypo-osmolar (200mOsm/L)Non hemolyticNon Immunogenic

Complications related to

glycine toxicity Hyperammonemia

Hypervolumic ,hypo-osmolar hyponatremia

Central pontine Myelinosis (CPM)

Hyperammonemia

glycine

Oxidative deamination

Ammonia Glyoxylic Acid

SYMPTOMS

Nausea Vomiting Altered mental status Muscle Aches Decreased visual acuity

Treatment

L-Arginine (to stimulate metabolism of

ammonia by the urea cycle )

Hypervolumic hypo-osmolar hyponatremia

Half life of glycine- 85min.

Eventually gets absorbed intracellularlyresulting in a surplus of intravascular free water

Exacerbated by ADH released during surgery

Serum Na levels decrease by 10 mmol/L for every liter of hypotonic fluid absorbed.

A patient will absorb at least 1 litres of medium before demonstrating symptoms

Also depend on pre-operative Na levels

Potential Effects

Hyponatremic encephalopathy- Irreversible brain damage

Cerebral odema

Increased intracranial pressure

Decreased cerebral blood flow

Hypoxemia & pressure necrosis of neurons

Symptoms depend upon the amount of medium absorbed Serum Na(mEq/L)

Associated signs and symptoms

135-142 Normal serum Na

130-135 Mild hyponatremia-apprehension,disorientation,nausea,vomiting,irritability,twitching,shortness of breath

125-130 Mild to moderate hyponatremiaDilute urine ,moist mucous memb, moist skin, pitting oedema ,polyuria , pulm.rales

<120 Severe hyponatremiaHyponatremic encephalopathy, CHF, lethargy, confusion ,twitching, focal weakness, convulsions, death.

<115 Possible brainstem herniation, grandmal seizures, coma, resp.arrest, mortalityupto85%

Treatment

Diuresis Correction of hyponatremia

Expectant management and spontaneous diuresis not an option

Central pontine myelinolysis

Represent brain injury resulting from brain dessication due to too rapid correction of hyponatremia.

Also described as “osmotic demyelinating syndrome”

An electronic pump for uterine distention with low viscosity fluid

Accountancy of fluid input and output is mandatory in any hysteroscopic procedure.

The severity and management of fluid overload depends on the nature of the medium in use.

Techniques of Measuring of

fluid intake and output

Gravitometry Serial serum Na measurements Volumetric fluid balance Ethanol monitoring method Parotid area sign

Gravitometry

A continuous automated weighing system

The patient undergoes operation on a bed-scale

Increase in weight is considered to imply fluid absorption.

Serial serum Na measurements

Best used where non-electrolyte distending medium is used

Best applied repeatedly duringsurgery

A poor guide to the degree of extracellular overhydration in the postop phase

Ethanol monitoring method

Considered to be one of the best methods

Not available to all surgeons

Does not detect extravasation of fluid until 15 to 20 minutes later.

Volumetric fluid balance method

Calculation of the difference between the amount of irrigating fluid instilled & the volume recovered

Can lead to significant underestimation of fluid absorption

Several pitfalls D/T Variations in bag-to-bag content Spillage Blood loss Urinary excretion. Commercially available containers of fluid may contain 5% to 10% more fluid than is specified.

Parotid area sign

This sign is a reflection of the interstitial edema that develops as aresult of the fluid overload.

Significant increase in the measured philtrum- mastoid prominence distance when fluid absorption was 1000 mL and above.

when the fluid absorption is equal to or more than 1000 mL,for every 500-mL increase in absorption, there is an approximately 0.5-cm increase in the philtrum-mastoid prominence distance.

Beyond 1500 mL fluid absorption, thedistance is generally above 0.5 cm and above 2 L, the distance increases by more than 1 cm

Sorbitol

6 –Carbon alcohol

Metabolised in liver to fructose and glucose- then to CO2 and H2O

3 % soln. is used for resectoscopic procedures

Hypo-osmolar

Non conductive

Overload with sorbitol

hyperglycaemia in the diabetic patient,

haemolysis hyper-volemia.

Mannitol

6 Carbon alcohol non –conductive Osmolarity similar to that of serum

(isotonic) Only 6-10% is absorbed cleared by kidneys diuretic properties

Saline

Produces a simple hypervolaemic state which may be treated by:

Insertion of a central venous line Administration of a diuretic & oxygen

Cardiac stimulants if necessary.

Saline overload

A blood pressure cuff may be applied to each limb to

occlude venous return which, in effect, performs a bloodless phlebotomy.

Fluid Overload Usually occur in the immediate

post- operative period.

Begin resuscitative procedures .

Surgery must be abandoned.

Prevention of Fluid Overload

1. Using appropriate distension media and delivery systems

2. Keeping operating times to a minimum

3. Avoiding entering the vascular channels

4. Keeping fluid pressures below 80mmHg and gas pressures below 100mmHg.

5. Meticulous accountancy of fluid balance.

6. The procedure must be abandoned if the deficit rises to 2 litres or there is evidence of venous congestion..

THANK YOU