distension media in hysteroscopy
TRANSCRIPT
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..
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