Download Anaesthesia for laparoscopic surgery

Presented by: Rashmi Bhatt
Moderator: Prof Surinder Singh
Laparoscopic surgery : risk vs benefits
 Laparoscopic vs open surgery
 Anaesthetic implications: respiratory, ventilatory
and haemodynamic alterations.
 Pre operative assessment
 Intraoperative management: anaesthetic
techniques, monitoring, complications (diagnosis
and management)
 Post operative considerations
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Surgical procedures have been improved to reduce trauma
to the patient, morbidity, mortality, and hospital stay, with
consequent reductions in health care costs. Starting in the
early 1970s, various pathologic gynecologic conditions
were diagnosed and treated using laparoscopy. This
endoscopic approach was extended to cholecystectomy in
the late 1980s.
laparoscopy results in multiple benefits compared with
open procedures and was characterized by better
maintenance of homeostasis which explains the effort to
use the laparoscopic approach for gastrointestinal (e.g.,
colonic, gastric, splenic, hepatic surgery), gynecologic
(e.g., hysterectomy), urologic (e.g., nephrectomy,
prostatectomy), and vascular (e.g., aortic) procedures.
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The pneumoperitoneum and the patient positions required
for laparoscopy induce pathophysiologic changes that
complicate anesthetic management.
Pneumoperitoneum decreases thoracopulmonary
compliance by 30% to 50%. Reduction in functional residual
capacity and development of atelectasis due to elevation
of the diaphragm and changes in the distribution of
pulmonary ventilation and perfusion from increased airway
pressure can be expected. However, increasing IAP to 14
mm Hg with the patient in a 10- to 20-degree head-up or
head-down position does not significantly modify either
physiologic dead space or shunt in patients without
cardiovascular problems.
the partial pressure of arterial carbon dioxide (PaCO2)
progressively increases to reach a plateau 15 to 30 minutes
after the beginning of CO2 insufflation.
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Any significant increase in PaCO2 after this period requires a
search for a cause independent of or related to CO2
insufflation, such as CO2 subcutaneous emphysema. The
increase in PaCO2 depends on the IAP. During laparoscopy with
local anesthesia, PaCO2 remains unchanged but minute
ventilation significantly increases.
mean gradients (Δa-ETCO2) between PaCO2 and the endtidal carbon dioxide tension (PETCO2) do not change
significantly during peritoneal insufflation of CO2.
the lack of correlation between PaCO2 and PETCO2 in sick
patients, particularly those with impaired CO2 excretion
capacity. Consequently, hypercapnia can develop, even in
the absence of abnormal PETCO2.
Postoperative intra-abdominal CO2 retention results in
increased respiratory rate and PETCO2 of patients breathing
spontaneously after laparoscopic cholecystectomy as
compared with open cholecystectomy.
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the increase of PaCO2 may be multifactorial: absorption
of CO2 from the peritoneal cavity, impairment of
pulmonary ventilation and perfusion by mechanical
factors such as abdominal distention, patient position,
and volume-controlled mechanical ventilation, the main
mechanism being absorption of CO2.
absorption of a gas from the peritoneal cavity depends
on its diffusibility, the absorption area, and the
perfusion of the walls of that cavity. Because CO2
diffusibility is high, absorption of large quantities of CO2
into the blood and the subsequent marked increases in
PaCO2 would be expected to occur. The limited rise of
PaCO2 actually observed can be explained by the
capacity of the body to store CO2 and by impaired local
perfusion due to increased IAP.
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Respiratory changes during the laparoscopic procedure
may contribute to increasing CO2 tension. Mismatched
ventilation and pulmonary perfusion can result from the
position of the patient and from the increased airway
pressures associated with abdominal distention.
At higher IAPs, the continued rise of PaCO2 without a
corresponding increase in results from an increase in
respiratory dead space. If controlled ventilation is not
adjusted in response to the increased dead space,
alveolar ventilation will decrease and PaCO2 will rise.
PaCO2 should be maintained within a physiologic range
by adjusting the mechanical ventilation. Except in
special circumstances, such as when CO2 subcutaneous
emphysema occurs, correction of increased PaCO2 can be
easily achieved by a 10% to 25% increase in alveolar
ventilation.
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Multifactorial: result from the combined effects of
pneumoperitoneum, patient position, anesthesia, and
hypercapnia from the absorbed CO2, reflex increases of
vagal tone and arrhythmias.
IN HEALTHY PATIENTS:
IAP higher than 10 mm Hg induces significant alterations of
hemodynamics. Results in decrease in cardiac output (10 to
30%), increased arterial pressures, and elevation of
systemic and pulmonary vascular resistances.
Heart rates remain unchanged or increased only slightly.
The decrease in cardiac output is proportional to the
increase in IAP. Cardiac output has also been reported to
be increased or unchanged during pneumoperitoneum.
changes in cardiac output are well tolerated by healthy
patients. Cardiac outputs, which decrease shortly after the
beginning of the peritoneal insufflation, subsequently
increase, probably as a result of surgical stress.
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mechanism of the decrease of cardiac output is
multifactorial: dec venous return (venacaval
compression, pooling of blood in the legs, and an
increase in venous resistance)
reduction in left ventricular end-diastolic volume
Cardiac filling pressures rise during peritoneal
insufflation due to increased intrathoracic pressure.
Right atrial pressure and pulmonary artery
occlusion pressure not reliable indices of cardiac filling
pressures during pneumoperitoneum.
Increased filling pressures can be achieved by fluid
loading or tilting the patient to a slight head-down
position before peritoneal insufflation, by preventing
the pooling of blood with intermittent sequential
pneumatic compression device,or by wrapping the legs
with elastic bandages.
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increase in systemic vascular resistance during the
existence of the pneumoperitoneum. not a reflex
sympathetic response to the decreased cardiac output.
Although the normal heart tolerates increases in afterload
under physiologic conditions,can be deleterious to patients
with cardiac disease.
The Trendelenburg position attenuates this increase in SVR,
the head-up position aggravates it. The increase in systemic
vascular resistance can be corrected by the administration
of vasodilating anesthetic agents, such as isoflurane, or
direct vasodilating drugs, such as nitroglycerin or
nicardipine.
mediated by mechanical and neurohumoral factors.
Catecholamines, the renin-angiotensin system, and
especially vasopressin contribute to increasing the
afterload.
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Increases in plasma vasopressin concentrations correlate
with changes in intrathoracic pressure and transmural right
atrial pressure. Mechanical stimulation of peritoneal
receptors also results in increased vasopressin release,
systemic vascular resistance, and arterial pressure.
The increase in SVR also explains why the arterial pressure
increases but the cardiac output falls. α2-adrenergic
agonists such as clonidine or dexmedetomidine and of βblocking agents significantly reduces hemodynamic changes
and anesthetic requirements. Use of high doses of
remifentanil almost completely prevents the hemodynamic
changes.
Increased IAP and the head-up position result in lower limb
venous stasis. may predispose to the development of
thromboembolic complications.
Urine output, renal plasma flow, and glomerular filtration
rate decrease to less than 50% of baseline values during
laparoscopic cholecystectomy.
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IN HIGH RISK CARDIAC PATIENTS: In patients with mild to
severe cardiac disease, the pattern of change in
haemodynamic parameters is qualitatively similar to that in
healthy patients but Quantitatively, these changes are
more marked.
IV nitroglycerin, nicardipine, or dobutamine has been used
in selected patients with heart disease. Nitroglycerin was
chosen to correct the reduction in cardiac output
associated with increased pulmonary capillary occlusion
pressures and systemic vascular resistance.
nicardipine may be more appropriate than nitroglycerin as
it acts selectively on arterial resistance vessels and does
not compromise venous return.This drug is beneficial in
case of congestive heart failure which can develop in the
early postoperative period Because normalization of
hemodynamic variables does not occur for at least 1 hour
postoperatively.
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CARDIAC ARRHYTHMIAS DURING LAPAROSCOPY: The
increased PaCO2 may not be the cause of the arrhythmias
occurring during laparoscopy. Arrhythmias do not correlate
with the level of the PaCO2 and may develop early during
insufflation, when high PaCO2 is not present.
Reflex increases of vagal tone may result from sudden
stretching of the peritoneum and during electrocoagulation
of the fallopian tubes. Bradycardia, cardiac arrhythmias,
and asystole can develop. Vagal stimulation is accentuated
if the level of anesthesia is too superficial or if the patient
is taking β-blocking drugs. Treatment consists of
interruption of insufflation, atropine administration, and
deepening of anesthesia.
arrhythmias may also reflect intolerance of the
hemodynamic disturbances in patients with known or
latent cardiac disease. Gas embolism can also result in
cardiac arrhythmias.
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the head-down position results in an increase in central
venous pressure and cardiac output. The baroreceptor
reflex consists of systemic vasodilation and bradycardia.
elevation of the intraocular venous pressure can worsen
acute glaucoma. Although the intravascular pressure
increases in the upper torso, the head-down position
decreases transmural pressures in the pelvic viscera,
reducing blood loss but increasing the risk of gas embolism.
With the head-up position, a decrease in cardiac output
and mean arterial pressure results from the reduction in
venous return. This compounds the hemodynamic changes
induced by pneumoperitoneum. The steeper the tilt, the
greater the fall in cardiac output.
The head-down position facilitates the development of
atelectasis. Steep head-down tilt results in decreases in the
functional residual capacity, the total lung volume, and the
pulmonary compliance. These changes are more marked in
obese, elderly, and debilitated patients.
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the laparoscopic approach allows for a reduction of the
acute phase reaction seen after open cholecystectomy. The
metabolic response is also reduced after laparoscopy. It
avoids prolonged exposure and manipulation of the
intestines and decreases the need for peritoneal incision
and trauma. Consequently, postoperative ileus and fasting,
duration of intravenous infusion, and hospital stay are
significantly reduced after laparoscopy.
Laparoscopy allows a significant reduction in postoperative
pain and analgesic consumption.
after laparotomy, patients complain more of parietal pain ,
whereas after laparoscopic cholecystectomy, patients
report also visceral pain, pelvic spasm , and shoulder-tip
pain resulting from diaphragmatic irritation. Residual CO2
pneumoperitoneum contributes to postoperative pain.
Benefits of intraperitoneal local anesthetic are greater after
gynecologic laparoscopy. Preoperative administration of
nonsteroidal anti-inflammatory drugs (NSAIDs) and of
cyclooxygenase-2 inhibitors decreases pain. Dexamethasone is
also effective in reducing postoperative pain.
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Respiratory dysfunction is less severe and recovery is quicker
after laparoscopy but diaphragmatic function remains significantly
impaired after laparoscopy. Thoracic epidural analgesia does not
improve lung function after laparoscopic cholecystectomy.
Postoperative pulmonary function of these patients, however, is
improved after laparoscopy as compared with laparotomy.
postoperative nausea and vomiting (PONV) (40% to 75% of
patients). Whereas perioperative opioids increase the incidence of
PONV, propofol anesthesia can markedly reduce the high incidence
of these side effects.
Intraoperative drainage of gastric contents also reduces PONV.
Intraoperative administration of droperidol and a 5hydroxytryptamine type 3 antagonist appears to be helpful in the
prevention and treatment of these side effects. Transdermal
scopolamine reduces nausea and vomiting after outpatient
laparoscopy.
Perioperative liberal intravenous fluid therapy can contribute to
decreasing these symptoms and to improve postoperative
recovery.
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Insufflation of inert gas (e.g., helium, argon) instead of CO2
avoids the increase in PaCO2 from absorption so
hyperventilation is not required. Also, the ventilatory
consequences of the increased IAP persist. The
hemodynamic changes are similar to those observed with
CO2. However, the use of these gases accentuates the
decrease in cardiac output, whereas the increase in
arterial pressure is attenuated.
Unfortunately, the low blood solubility of the inert gases
raises the issue of safety in the event of gas embolism.
Another alternative is gasless laparoscopy. The peritoneal
cavity is expanded using abdominal wall lift obtained with a
fan retractor. This technique avoids the hemodynamic and
respiratory repercussions of increased IAP and the
consequences of the use of CO2. gasless laparoscopy
compromises surgical exposure and increases technical
difficulty
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CO2 Subcutaneous Emphysema: can develop as a
complication of accidental extraperitoneal insufflation but
can also an unavoidable side effect of certain procedures
that require intentional extraperitoneal insufflation, such
as inguinal hernia repair, renal surgery, and pelvic
lymphadenectomy.
Any increase in PETCO2 occurring after PETCO2 has plateaued
should suggest this complication. prevention of
hypercapnia by adjustment of ventilation becomes almost
impossible.
laparoscopy must be temporarily interrupted to allow CO2
elimination and can be resumed after correction of
hypercapnia using a lower insufflation pressure.CO2
pressure determines the extent of the emphysema and the
magnitude of CO2 absorption.
patient may be mechanically ventilated until hypercapnia
is corrected, particularly in COPD patients, to avoid an
excessive increase in the work of breathing.
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Pneumothorax, Pneumomediastinum, Pneumopericardium:
Embryonic remnants constitute potential channels of
communication between the peritoneal cavity and the pleural and
pericardial sacs, which can open when intraperitoneal pressure
increases. Defects in the diaphragm or weak points in the aortic
and esophageal hiatus may allow gas passage into the thorax.
Pneumothoraces may also develop secondary to pleural tears
during laparoscopic surgical procedures at the level of the
gastroesophageal junction.
Capnothorax (CO2 causing a pneumothorax) reduces
thoracopulmonary compliance and increases airway pressures.
absorption from the pleural cavity is greater than from the
peritoneal cavity; PaCO2 and PETCO2 also increase.
spontaneous resolution of the pneumothorax occurs within 30 to
60 minutes without thoracocentesis. When capnothorax develops
during laparoscopy, treatment with positive end-expiratory
pressure (PEEP) is an alternative to chest tube placement, but if
the pneumothorax is secondary to rupture of preexisting bullae,
PEEP must not be applied and thoracocentesis is mandatory.
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Endobronchial Intubation: Cephalad displacement of the
diaphragm during pneumoperitoneum results in cephalad
movement of the carina potentially leading to an
endobronchial intubation. Generally occurs during
procedures in the head-down position and in the head-up
position. results in a decrease in the oxygen saturation
with an increase in plateau airway pressure.
Risk of Aspiration of Gastric Contents: Patients undergoing
laparoscopy might be considered to be at risk for acid
aspiration syndrome . However, the increased IAP results in
changes of the lower esophageal sphincter that allow
maintenance of the pressure gradient across the
gastroesophageal junction and that may therefore reduce
the risk of regurgitation. Furthermore, the head-down
position should help to prevent any regurgitated fluid from
entering the airway, provided airway is secured or airway
reflexes are not obtunded.
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Gas Embolism: most feared and dangerous complication of
laparoscopy. Intravascular injection of gas may follow
direct needle or trocar placement into a vessel, or it may
occur as a consequence of gas insufflation into an
abdominal organ. develops principally during the induction
of pneumoperitoneum, particularly in patients with
previous abdominal surgery.
CO2 is used most frequently as it is more soluble in blood.
Rapid elimination also increases the margin of safety in
case of intravenous injection of CO2. this explains the
rapid reversal of the clinical signs of CO2 embolism with
treatment. Consequently, the lethal dose of embolized CO2
is approximately five times greater than that of air.
Volume preload diminishes the risk of gas embolism and of
paradoxical embolism. Ventilation-perfusion mismatching
develops with increases in physiologic dead space and
hypoxemia.
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Early events, occurring with 0.5 mL/kg of air or less,
include changes in Doppler sounds and increased mean
pulmonary artery pressure. When the size of the embolus
increases (2 mL/kg of air), tachycardia, cardiac
arrhythmias, hypotension, increased central venous
pressure, alteration in heart tones (i.e., millwheel
murmur), cyanosis, and ECG changes of right-sided heart
strain can develop.
Pulmonary edema can also be an early sign. pulse oximetry,
capnometry and capnography are valuable in providing
early diagnosis of gas embolism and determining the extent
of the embolism. PETCO2 decreases in the case of embolism
due to fall in cardiac output and the enlargement of the
physiologic dead space.
Initially there may be increase in PETCO2 secondary to
pulmonary excretion of the CO2, which has been absorbed
into the blood. Aspiration of gas or foamy blood from a
central venous line is also confirmatory.
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Management: immediate cessation of insufflation and
release of the pneumoperitoneum. The patient is placed in
steep head-down and left lateral decubitus (Durant)
position.
Discontinue N2O to allow ventilation with 100% O2 to
correct hypoxemia and reduce the size of the gas embolus.
Hyperventilation increases CO2 excretion and is required
for increased physiologic dead space.
a central venous or pulmonary artery catheter may be
introduced for aspiration of the gas.
Cardiopulmonary resuscitation must be initiated if
necessary. External cardiac massage may be helpful in
fragmenting CO2 emboli into small bubbles.
The high solubility of CO2 in blood, results in rapid
absorption from the bloodstream,and clinical signs of CO2
embolism revert rapidly.
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Intestinal injuries account for 30% to 50% of these and
remain undiagnosed during laparoscopy in one half of the
cases. Vascular complications also account for 30% to 50%.
Burns were responsible for 15% to 20% of the reported
complications.
Bowel perforation, common bile duct injury, and significant
hemorrhage are seen in lap cholecystectomy. Laparoscopic
cholecystectomy was accompanied by a greater frequency
of minor operative complications, whereas open
cholecystectomy had a more frequent rate of minor general
complications.
retroperitoneal hematoma can develop insidiously and
result in significant blood loss without major
intraperitoneal effusion, leading to delayed diagnosis.
During gynecologic laparoscopy, complications occur more
frequently during the creation of pneumoperitoneum and
the introduction of trocars, whereas during gastrointestinal
surgery they are more closely related to the surgical
procedure itself.
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Pneumoperitoneum is undesirable in patients with
increased intracranial pressure (e.g., tumor,
hydrocephalus, head trauma) and hypovolemia.
Laparoscopy can be performed safely in patients with
ventricular peritoneal shunt and peritoneojugular shunt
that are provided with unidirectional valve resistant to
IAPs used during pneumoperitoneum.
In patients with heart disease, cardiac function should
be evaluated , particularly in case of compromised
ventricular function . Patients with severe congestive
heart failure and terminal valvular insufficiency are
more prone to develop cardiac complications than
patients with ischemic cardiac disease during
laparoscopy.
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If left ventricular ejection fraction < 30%: pre op
echocardiography. Intraoperative monitoring: Intraarterial line, Pulmonary artery catheter,Transesophageal
echocardiography, Continuous ST-segment analysis.
Gasless laparoscopy or laparotomy may be considered.
Intraoperative Management: Slow insufflation,Low intraabdominal pressure ,Hemodynamic optimization before
pneumoperitoneum (preload augmentation) Patient tilt
after insufflation. Use of remifentanil, vasodilating
anesthetic and drugs (nicardipine, nitroglycerin),
cardiotonic agents. Preferably an experienced surgeon.
patients with renal failure deserve special care to
optimize hemodynamics during pneumoperitoneum, and
the concomitant use of nephrotoxic drugs should be
avoided.
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General anaesthesia: General anesthesia with endotracheal
intubation and controlled ventilation is the safest and most
commonly used technique and therefore is recommended for
inpatients and for long laparoscopic procedures.
controlled ventilation must be adjusted to maintain PETCO2
between 35 and 40 mm Hg;15% to 25% increase of minute
ventilation, except when CO2 subcutaneous emphysema develops.
Increase of respiratory rate rather than of tidal volume may be
preferable in patients with COPD and in patients with a history of
spontaneous pneumothorax or bullous emphysema.
The laryngeal mask airway results in fewer cases of sore throat
and may be proposed as an alternative to endotracheal intubation;
does not protect the airway from aspiration of gastric contents.
decreased thoracopulmonary compliance during
pneumoperitoneum frequently results in airway pressures
exceeding 20 cm H2O. The ProSeal laryngeal mask airway may be
an alternative to guarantee an airway seal up to 30 cm H2O.
Local and regional anesthesia