Pneumoperitoneum Flashcards
Define pneumoperitoneum
Insufflation of gas (usually CO2) into the peritoneal cavity to separate the visceral contents from the abdominal wall
Why is CO2 the gas of choice
Non combustible (can use diathermy and laser)
colourless
Non-toxic
Highly soluble
What is the usual initial insufflation rate and pressure
4-6L/min to a pressure of 10-20mmHg
What is the usual maintenance gas flow rate
200-400mL/min
What are the usual maximal IAP for abdominal and pelvic surgeries
Abdominal - 14mmHg
Pelvic - 25mmHg
Outline the major respiratory complications on initiation of the pneumoperitoneum
Risk of ETT displacement (bronchial intubation) with upward shift of Thx organs
Inc IAP reduces Thx compliance and inc airway pressures, dec Tv -> dec ventilation
Dec FRC, basal atelectasis and inc V/Q mismatch -> hypoxia
Pulmonary gas embolus
Pneumothorax
Risk of aspiration from regurgitation
CO2 absorption -> inc PaCO2
Outline the major CVS complications on initiation of the pneumoperitoneum
Peritoneal stretch -> stimulate intense vagally mediated bradycardia
Initial inc in VR -> inc CO
Later dec CO from dec VR and dec myocardial contractility
Inc IAP -> inc SVR & inc catecholamine release -> inc afterload
MAP can inc or dec depending on above factors
Poor cardiac reserve = tachycardia and dec coronary blood flow and possible cardiac ischaemia
Major abdo vessel injury -> severe haemorrhage
What thoracic complications may occur
Extra-peritoneal gas insufflation (misplaced trocar, anatomical defects, gas under high pressure)
Pneumomediastinum, pneumopericardiam, pneumothorax, subcut emphysema
What are the clinical signs of a possible pneumomediastinum or pneumothorax
and how is it managed
Rapidly rising EtCO2, rising airway pressures and falling SpO2
Evacuate the pneumoperitoneum, wait, resume surgery at lower insufflation
If significant cardiac or respiratory compromise may need needle decompression
