6.2 Laparoscopy + Effects

Question 1

A 45-year-old man is scheduled for a laparoscopic Nissen fundoplication under general anaesthesia.
He is graded ASA 1.
a) Describe how laparoscopy can cause adverse effects in this patient. (70%)

Lap
posoition

B C

Answer 1

Trocars:
» Unintended visceral or vascular injury.
» Risk of intravascular carbon dioxide embolus.
» Surgical emphysema.

Steep head-up position:
» Airway: accidental extubation.
» Cardiovascular: venous pooling, decreased venous return, decreased cardiac output, hypotension, myocardial ischaemia.
» Neurological:
reduced intracerebral perfusion pressure.
» Cutaneomusculoskeletal:
pressure points, security on table.

Pneumoperitoneum:
» Respiratory:
• Reduced functional residual capacity (already reduced due to
anaesthesia), atelectasis, V/Q mismatch, reduced compliance.
• Carbon dioxide absorption increasing PaCO2.
• Risk of barotrauma due to elevated airway pressures used to maintain
tidal volume and etCO2 against raised intraperitoneal pressure.

> > Cardiac:
• On inflation, autotransfusion from splanchnic vessels.

• Then, compression of inferior vena cava causing reduced venous return in the face of increased intrathoracic pressure. Stroke volume
falls resulting in reflex tachycardia.

• Compression of aorta and release of neurohumoral factors (renin– angiotensin–aldosterone system, catecholamines)
cause an increase in systemic vascular resistance and so cardiac output is maintained
overall. Myocardial workload is therefore increased, risking ischaemia in susceptible individuals

Question 2

Neuro to hepatic

A 45-year-old man is scheduled for a laparoscopic Nissen fundoplication under general anaesthesia.
He is graded ASA 1.
a) Describe how laparoscopy can cause adverse effects in this patient. (70%)

Answer 2

> > Neurological:
• Raised PaCO2 (if uncorrected) causes
cerebral vasodilatation.

• If cardiac output is significantly
reduced in the head-up position, may
compromise cerebral perfusion pressure.

> > Gastrointestinal:
• Patient already at risk of reflux as evidenced by the need for this surgery –
further risk due to raised intra-abdominal pressure.

• Compromised splanchnic blood flow.

> > Haematological:
• Venous stasis, risk of deep vein thrombosis.

> > Renal:
• Raised intra-abdominal pressure causes increased renal vascular resistance, with raised renal venous pressure causing reduced glomerular flow rate, reduced urine output.

• Risk of acute kidney injury in susceptible individuals or with prolonged surgery.

> > Hepatic:
• Reduced liver perfusion.

Question 3

b) How may these effects be minimised? (30%)

Answer 3

Patient selection (ensure that the patient has sufficient cardiac and respiratory reserve to cope with the process),

good surgical technique
(thus minimising risk of trocar damage and limiting duration and pressure of pneumoperitoneum).

A: Check tube position after movement, inflation of abdomen.

B: Intubate, positive pressure ventilation to control PaO2 and PaCO2, use PEEP.

C: Ensure adequate circulating volume, management of hypotension with inotropic rather than vasopressor drugs, ensure that airway pressures do not
further compromise cardiac output. Consider intra-arterial blood pressure monitoring and cardiac output monitoring for long procedures or in patients
with cardiac comorbidities. Avoid excessive intraperitoneal pressure and limit duration.

D: Adequate filling and blood pressure.

G: Minimise face mask ventilation pre-intubation to reduce gastric distension and obscuration of surgical field, thus reducing risk of stomach injury.
Deflate
stomach with oro- or nasogastric tube if this has occurred. Intubation reduces risk of reflux due to raised intra-abdominal pressure.

Rapid sequence or modified rapid sequence induction may be indicated for preexisting
reflux.

H: Thromboembolic deterrent stockings, pneumatic compression devices, postoperative low-molecular-weight heparin.

J: Padding, ensure secure positioning on the table.

K: Adequate filling and blood pressure.

L: Adequate filling and blood pressure.