Lectures C5-6 – Minimally invasive surgery. Technical background. Basic surgical
techniques. Physiology of laparoscopy
Minimally Invasive Surgery = Minimal Access Surgery = Video-Endoscopic Surgery =
Magnified Surgery
History of minimally invasive surgery
1706. “Trocar” is first mentioned (trois (3) + carre (side), or trois-quarts / troise-quarts - old
French).
1806. Phillipp B. Bozzini (1773-1809) is often credited with the use of the first endoscope. He
used a candle as light source to examine the rectum and uterus.
1879. Maximilian Nitze and Josef Leiter invented the "Blasenspiegel” (cystoscope).
1938. A spring-loaded needle was invented by Veres János (1903-1979). Although the
„Veress needle” was originally devised to create a pneumothorax, the same design has been
incorporated in the current insufflating needles for creating a pneumoperitoneum.
1985. Dr. Erich Mühe of Böblingen, West Germany, performed the first laparoscopic
cholecystectomy in 1985 (with a “galloscope”). After nearly 100 succesful operations, a
patient died in a complication not related to the procedure itself. German medical leaders
declared it „human experimentation” and Mühe was brought to court. The charge was
homicide, and he was sentenced.
1987. Phillipe Mouret, in Lyon, is usually credited with the first successful human
laparoscopic cholecystectomy (LC). Perrisat, Dubois and colleagues in communication with
Mouret, performed laparoscopic cholecystectomies shortly thereafter. In 10 years, the LC
became standard technique for cholecystectomy.
The goals of minimally invasive surgery
 To replace traditional, open surgery
 To transfer traditional open techniques into the laparoscopic field
 It is necessary to maintain - and surpass - results and standards achievable by open
means
 Surgery undergoes constant evolution: minimally invasive surgery is „cutting edge”
 Future projections: will make up ~70% of compartment surgery (!)
Established procedures (as of 2005)
 Laparoscopic cholecystectomy
 Diagnostic laparoscopy
 Laparoscopic appendicectomy
 Laparoscopic fundoplication
 Laparoscopic Heller's myotomy
 Laparoscopic adrenalectomy
 Laparoscopic splenectomy
Procedures under evaluation
 Laparoscopic hernia repair
 Laparoscopic colectomy
 Laparoscopic nephrectomy for living related donor
 Parathyroidectomy
 Laparoscopic surgery for perforated duodenal ulcer
Robotic surgery
This is truly the cutting edge of surgery. Most common is adult cardiac procedures.
The major benefits are in decreasing the “human factor”, like shaking of hands, hand-eye
coordination problems, etc.
• There are two main types of systems: Da Vinci and Zeus.
• Da Vinci: better manipulators
• Zeus: smaller instruments (3 mm)
• Learning curve: first fundoplication took 4.5 hrs surgical time, now 1.5 hrs, with
corresponding decreases in setup time.
Foetoscopic surgery
In-utero procedures done laparoscopically. Some of the procedures being performed include:
• Bladder decompression
• Radio ablation of abnormal vessels in twin gestations
• Laparoscopic division of amniotic bands and drainage of hydrothorax
Advantage of minimal access surgery
 Diagnostic + therapeutic procedures
 Better cosmesis.
 Fewer postoperative complications, hernias / infections
 Fewer postoperative adhesions. Main causes
 fewer hemorrhagic complications;
 less peritoneal dehydration;
 lower degree of tissue trauma;
 lower amount of foreign material (sutures).
 Shorter postoperative recovery. Main causes:
 less tissue trauma;
 stress in general is lower
 less postoperative pain
 Patients are able to return to their normal activities faster (6 days).
Mechanism of wound healing is identical (!) – recovery depends on:
o indication (cause of illness)
o healing time of incisions/ports and
 insults of organs and abdominal wall,
 stress caused by general anesthesia
 peritoneal damage
 Faster recovery
 Laparoscopy: 7-14 days
 Laparotomy: 4-6 weeks
 Economical advantage
 decreased hospital stay will decrease surgical costs by 50-60%
 post. op. recovery time after endoscopic surgery can be shortened by 4-6x
Disadvantages of minimal access surgery
 Lack of tactile feedback
 Increased technical expertise required
 Possible longer duration of surgery
 Increased risk of iatrogenic injuries
 Difficult removal of bulky organs
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More expensive
Non-corrigated coagulation problems
The laparoscope
The term originates from „lapar” (Gr) = "the soft parts of the body between the rib margins
and hips” – loin; skopein (Gr) = "to see/ view / examine.
The laparoscopic tower
Parts (in general): 1. monitor (screen), 2. video system (control unit, etc), 3. light source, 4.
insufflator ± carbon dioxide cylinder, 5. suction and irrigation, 6. electrocautery device, 7.
data storage system. The endoscope and camera are attached to the units of the tower with
cables.
Endoscopes - background
 Traditional system. Diameter of lens < length of endoscope. Distance between lenses
is large, the light travels through long distances between lenses, light absorbance 9095% → image is dark.
 B. Hopkins optics (1966)- rod lens system. Space between lenses is filled with glass
and air. Light transfer ↑ loss/absorbance ↓ (approx. 70%) → much better image
quality
Endoscopes – optical characteristics
a. View
Angle between the of objective and other lenses within the endoscope: determines the
direction of the view. In operating endoscopes: 0°-30° - 0°- endoscope: the amount of light
forwarded to the ocular is the highest.
b. Field
Between the borders of the image - „how wide is the view"
c. Focus
Increasing / decreasing the magnification either by turning the laparoscope's zooming ring, or
by advancing laparoscope toward or withdrawing it from the targeted area. The depth of field
of the laparoscope is measured in centimeters: the closer the objective is to the tissue, the
shallower the depth of field.
d. Light loss
Hopkins endoscopes > 12 lenses. Only 20%- of the light leaves the ocular part of the
endoscope.
Light guide
The illumination is transmitted to the laparoscope via a flexible fiberoptic light guide (180250 cm long, 0.5-1.0 cm OD). This illumination is essentially cold - most of the lamp heat is
not transferred to the laparoscope.
Light source
• Working in a closed environment requires a source of external illumination.
• Currently the 150-300 W fan-cooled xenon light source is used to provide colorcorrected light for extended periods of time without overheating.
The video system
 The coupler between the laparoscope and the video camera is equipped with a
focusing and zooming ring.
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Camera head: attached to the endoscope, receives the image and transfers to
electric signals. The basis of laparoscopic cameras is the solid-state silicon
computer chip the CCD (charge-coupled device). (Willard Boyle and George
Smith, 1969, Bell Laboratory).
Control unit: receives the signals of the camera head, converting the optical
image into the initial video signal.
The video sensor (head) can contain 1- or 3-chip sensor. The 1-chip sensor is
economical, whereas the 3-chip involves an improved image quality.
One-chip camera: single CCD sensor, which is responsible for converting the
optical image into the initial video signal that is processed and displayed on the
video monitor.
The 3-chip camera has separate red, green and blue sensors for improved color
definition, and a RGB connection to the monitor is recommended.
Physiology of laparoscopy. Pneumoperitoneum - background
First used in gynecology; air by hand. Insufflator: closed system for gas insufflation; pressurecontrolled device for creating and maintaining pneumoperitoneum.
In addition to the delivery of gas, insufflators have the ability to control the maximal flow rate
of the gas and the pressure of gas (< 15 mmHg) within the abdomen.
Intraabdominal pressure (IAP)
 Adult patients: IAP < 15 mmHg
 Pediatrics: < 6 mmHg
Pneumoperitoneum - technique
 Closed technique, Veress needle
 Open: Hasson technique (1971).
 Open technique: morbidity is less, BUT: the type of complications is the same (!)
Physiology of laparoscopy. Example: laparoscopic cholecystectomy
o CO2 at 15 mmHg in healthy patients
o Overall: decrease CO and SV, increase MAP and SVR
o No adverse events
Advantages
o a large, dome-like space is created → displacement of viscera → enabling the
surgeon to see and move about the instruments;
o The gas pressure of an established pneumoperitoneum is above the
surrounding atmospheric pressure.
o P venous < IAP → control of capillary and venous bleeding
Ideal gas
 Colorless
 Biologically inert
 Absorbed harmlessly and rapidly into the bloodstream
 Does not support combustion
 Cheap
 High flow (> 16 l/min)
CO2
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Not inert, but widely used
Cheap
Easily transported
Alternatives: helium, nitrous oxide
Warm and humidify the gas to prevent hypothermia and desiccation
Insufflator reading/monitor
o Gas composition
o IAP
o Gas volume and flow rate
o Alarm system that sounds when the pressure exceeds the preset level
o Automatic exsufflation
o Gas:
 Cylinder (50-200 bar pressure)
 Central unit (3.5-5 bar).
o Inlet valve for connection to a gas tank and an outlet port from which sterile
plastic tubing is passed to the patient and is used to deliver the gas.
o IAP = average 12 mmHg (1 bar=760 mmHg) → reduction to 50-80 mmHg
o Lowest gas flow (1 l/min) during the initial phase of pneumoperitoneum
(introduction of Veress needle).
o IAP < 12-15 mmHg → venous dysfunction.
o IAP > 12-15 Hgmm = CI ↓, gas exchange problems
o Continuously high IAP → organ damage
Hemodynamic complications
o Can die from tension pneumoperitoneum = equivalent to a
intraabdominal compartment syndrome
o Decrease in organ function due to decreased microcirculation
o Tension pneumoperitoneum: IAP > 40 mmHg, very restricted CO,
potentiated by hypovolemia, dysrhythmias (due to hypercapnia, vagal
stimulation)
o Decreased femoral vein pressure → stasis
Circulation
Venous outflow (preload) ↓
CO ↓
HR ↑
MAP ↑
TPR (afterload) ↑
PVR ↑
Hemodynamic changes are more significant in reverse Trendelenburg position AND
incidence and risk of deep venous thrombosis is increased.
Trendelenburg / anti-Trendelenburg position: only when the condition is stable, AFTER the
pneumoperitoneum.
ABG
o CO2 in systemic circulation: hypercapnia + respiratory acidosis.
o Insufflation: PaCO2 = 8-10 mmHg rise together with a decrease in pH.
o Equilibration:15-20 min after pneumoperitoneum.
Respiratory effects
o IAP ↑: intrathoracal pressure ↓ lung compliance ↑ airway resistance
(restrictive syndrome).
o Compression of lower lung lobes (cause: intraabdominal pressure +
anesthesia-induced diaphragm relaxation) → lung volumen ↓, dead
space ↑ (Trendelenburg position will enhance these effects). Effect
likely irrelevant in healthy patients
o Possibility to improve gas exchange: positive end expiratory pressure
(PEEP)
Kidneys (excretion)
o IAP <15 mmHg: consequences are clinically not significant.
o Higher IAP: decreased kidney perfusion, glomerular fiiltration rate, UO
o Direct pressure on kidney parenchyma, renal arteries and veins: renal
function will decrease linearly with pressure
o Oliguria: decreased UO seen universally (animal and human studies)
o Can have anuria: depends on degree of IAP and OR time. Increased in
patients with CVS, hemodynamic, and renal dysfunction. Reversible
(no renal failure reported). Watch for fluid overload.
Oliguria etiologies
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Likely multifactorial
Ureteral obstruction
Decrease in CO and renal blood flow
Renovascular or parenchymal compression
Compression is associated with decreased U/O
Mediated by increased renin secretion
May also directly impact RBF, capillary flow, and tubular flow →
decrease in GFR → decreased U/O
o Central venous congestion - neuroendocrine mechanism
Hormonal changes
Renin
Increases with increased IAP; relative cortical ischemia; redistribution of RBF from cortex to
medulla
• ACE-I does not prevent oliguria
• Stimulation of the neurohormonal system is independent from the quality of gases
• Vasopressin + renin-aldosteron-angiotensin = vasoconstriction.
Endothelin
• Potent vasoconstrictor
• Increased in renal vein in pneumoperitoneum
• May maintain MAP despite decreased CO with laparoscopy
Liver function
o Hepatic and portal circulation progressively decreasing: increased liver
enzymes in plasma.
Microcirculation
o Mechanical compression of mesenteric vessels, decreased splanchnic
microcirculation.
Recommendations
• Use lowest possible insufflation pressures
• Maximize fluid status preoperatively
• Avoid overhydration interoperatively in response to oliguria
• Consider preop. pulmonary and cardiac status
• Most changes reverse quickly postop.
Complications of pneumoperitoneum
20-40% of all complications is related to pneumoperitoneum. Rare (in <1% of all
laparoscopy) but severe.
o Vessel injury (0.04-0.05%) less frequent than organ damage but potentially
more severe (mortality: 8-17%). Most common: epigastric vessels, vessels of
greater omentum. Large veins, arteries can be punctured during the insertion of
the Veress needle or first trocar (aorta, vena cava, vena portae, iliaca, etc.).
Rare but 50% mortality.
o Organ injuries: small bowel, large bowel, liver. If untreated (in 24h) severe
septic complication (0.06-0.14% incidence with mortality >20%).
o Air emboli (<0.6%) rare but potentially lethal. Most common: lung. Rare:
coronaris, brain
Air emboli - main mechanisms of air embolism:
o During the induction of pneumoperitoneum direct puncture of vessels
with Veress needle or first trocar;
o Parenchymal organ (e.g. liver) intraoperative vessel damage;
o Rare: helium with high intraabdominal pressure (>20 mmHg).
Gases
o CO2: danger of emboli is negligible (2 ml/kg/min CO2 iv
(experimental) did not cause lethal complications.
o N2O: if pneumoperitoneum is not kept up with regular filling N2O gas
concentration (anesthesiology!) will increase in the abdomen →
increased risk of embolizaton.
o He: poor tolerance - 0.1 ml/kg/min causes severe cardiac side-effects.
Prevention of air emboli
o Safe trocar use
o Intraabdominal pressure control
o Soluble gases
Diagnosis
o Trans-oesophageal Doppler UH (no routine use in laparoscopic
surgery);
o Capnography (!): end-tidal CO2 ↓(consequence of decreasing CO +
increasing dead space).
o Parallel decrease in PaO2: highly suspicious.
o ECG changes: late, large embolization (!).
Therapy
o Stop insufflation, exsufflate pneumoperitoneum;
o Left sided Trendelenburg position: decreases embolization from the
right heart to pulmorary circulation;
o N2O stop + 100% O2 - hyperventilation (goals: decrease dead space,
increase excretion of CO2 through lungs, correction of hypoxia);
o CV catheter into pulmonary artery → gas aspiration.
Remarks
Elimination of CO2 in lungs is promoted by the large cc gradient. Signs are usually
quickly improving and the condition is reversible without treatment.
Subcutaneus emphysema
Cause
o CO2 under pressure dissects tissues.
o Accidental or intentional (extraperitoneal surgery).
o Increasing CO2 absorption → PaCO2 ↑ (proportional to the severity of
emphysema).
o Suspicious: PaCO2 ↑ during the first 20 min of pneumoperitoneum.
Therapy
o RR ↑ = stabilization, stop insufflation to get rid of CO2.
Pneumothorax
Cause
o P intraabdominal ↑ = opening of embrional peritoneo-pleural channels
→ „spontaneos” Ptx.
o Nearly always in case of diaphragmatic preparations (classical:
fundoplication).
Consequences
o Increased airway pressure
o PaCO2 ↑
o PaO2 ↓
o O2 saturation ↑
o Pulmonary resistence ↑
o CO ↓, compensatory HR ↑
Treatment of pneumothorax
o PEEP (5 Watercm) = lung reinflation + CO2 ex
o N2O stops, FiO2 ↑, P intraabdominal ↓.
o Thoracocentesis: usually not necessary, CO2 will be absorbed in
approx. 30 min and Ptx will cease.
Important: Discern CO2 + PTX and rupture of alveoli (emphysema – which is a consequence
of PEEP). Emphysemic rupture: PEEP will aggravate signs → PTX can not be eliminated
„spontaneously”, therapy: chest tube (!)
Increased intraabdominal pressure
o „Surgical”: circulatory and respiratory changes, large individual
differences in tolerance. Significant rise: increased risk of
complications caused by diffusible gases (air embolus, subcutaneous
emphysema).
o „Anaesthesiology”: insufficient depth of anaesthesia/narcosis/muscle
relaxation → < 20 mmHg pressure + strong contraction of abdominal
muscles.
o Quick intraabdominal volume load (e.g. suction/irrigation) or
simultaneous use of other gases (e.g. argon coagulation).
„Laparoscopic” pain
o The character of this pain differs from open laparotomy.
o Laparotomy/open surgery: dominating abdominal pain
o Laparoscopic pain: deep visceral pain (this is covered by abdominal
pain during open surgery)
o Characteristics: pain in shoulder, shoulder blade (cause:
pneumoperitoneum-induced diaphragm tension + CO2 –induced acidic
irritation
Therapy
o CO2 complete removal
o irrigation with warm saline at the end of the procedure
o local anesthetic solutions (e.g. bupivacaine): subdiaphragmatic use
Diathermy
o Bipolar (insulated) system: places the tissue between two electrodes, so
the current passes from one electrode to the other through the
interposed tissue. The technology of precision coagulation: peripheral
vascular and microsurgery
o Monopolar (grounded): the ground pad should have a surface area of
approx. 50 cm2, placed over muscular tissue, and coated with a
conductive gel to enhance conductance.
Suction and irrigation
o Quick removal of abdominal fluid is mandatory.
o Irrigation + suction can not be separated → in most of the tools these
functions are joined.
o Central unit: electric pump with continuous 180 mmHg positive and
500 mmHg negative pressure. Fluids: warm isotonic solutions (saline)
Large amounts of fluid
o Treatment of generalized, acute infections;
o Bile duct operations;
o Hydro-dissection.
Possibilities
o Infusion sack + pressure – e.g. cuff of manometer. Infusion set is
attached to a suction/irrigation unit. Advantage: simple. Disadvantage:
pressure is usually too low, fluid volume is restricted.
o Pneumatic (air) devices: single use sets using central compressed air
systems. Advantage: relatively cheap, pressure is adequate.
o Peristaltic pumps with adjustable roller pump
o Complete, single-use sets. Irrigation unit contains a pressure-generating
electric pump
„Open surgery” in closed environment
Hand-Assisted Laparoscopic Surgery (HALS): clinical and visual benefits of laparoscopy +
tactility and control of open surgery. Pneumoperitoneum is kept up by non-adhesive sealing:
the surgeon reaches trough a valve with long gloved hand and directly manipulates the tissue.
The other hand is using laparoscopic instruments, viewing all this on the video display.
Access
o Veress needle: blunt obturator retracts on contact with solid tissue to
reveal a cutting tip.
o Once the peritoneal cavity is entered, gas may be instilled through the
hollow shaft of the needle.
o The needle is then removed, and a trocar/cannula is inserted through
the same site. This method is called: blind or closed technique
Trocar
Once the pneumoperitoneum is established, a cannula or port must be inserted to allow the
passage of the laparoscope and operating instruments into the abdomen.
o Trocar: a sharply pointed shaft, usually with a 3-sided point.
o A trocar may be used within a cannula (tube) to be inserted into a body
cavity.
o 3 main parts 1. trocar 2. cannula (working channel); 3. trocar valve
o In practice, the term „trocar” is commonly used to describe the whole
trocar-cannula apparatus.
o As a safety feature, most disposable cannulas are equipped with a
plastic sleeve, which automatically covers the cutting obturator once it
has pierced the abdominal wall.
o In order to prevent gas leaking from the port sites, the trocar
incorporates a valve. This allows the insertion of instruments without
the escape of gas.
Hand instrumentation
o Special instrumentation.
o Remote and closed surgical environment
o The instruments jaws located within the closed environment, the handle
external.
o Length: 10-50 cm (most commonly 30 cm), depending on the distance
of target tissue from the point of access.
o Disposable (single-use), reusable (on a long-term basis), or "resposable" (features of both disposable and reusable) instruments.
Laparoscopic cholecystectomy
One of the most common laparoscopic procedures; in 2006: standard procedure for
cholelithiasis and cholecystitis.
Contraindications
o High risk for general anaesthesia
o Morbid obesity
o Signs of gallbladder perforation (abscess, peritonitis, or fistula)
o Giant gallstones or suspected malignancy
o End-stage liver disease with portal hypertension and severe coagulopathy
Laparoscopic appendectomy
First performed in 1987, successful in 90-94% of attempts.
Advantages
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increased cosmesis
decrease in the postoperative wound-infection rate.
shortened convalescent period
shortened hospital stays.
Disadvantages
o increased cost
o operating time approx. 20 min longer than that of open appendectomy.
Contraindications
o significant intra-abdominal adhesions
o pregnancy beyond the first trimester
In vitro training
o Instrument use/suturing in the endoscopic field is based on
microsurgical techniques.
o Intracorporeal suturing in the minimal access surgery field is based on
precision techniques developed by Alexis Carrel (1873-1944), Nobel
laureate (1912) and Charles Claude Guthrie (1880-1963).
o First step: practice is a trainer box with ports for instruments and the
scope. In a pelvi-trainer („box-trainer”, „MAT-trainer”) one should
practice on the same quality optical-video-monitor setup as used in the
operating room.
o Greater precision and improved results are possible with laparoscopic
techniques - added benefit of magnification and better visualization