PNEUMOPERITONEUM, POSITION AND SPINAL ANAESTHESIA
“Trendelenburg-Lagerung” by Willy Meyer
(Original text : Archiv für Chirurgie 1885). Licensed under Public domain via Wikimedia Commons –
Oesophageal Doppler monitoring has been used widely in laparoscopic surgery [1-8] and has the best precision to see small changes in SV following fluid challenges, carefully and safely guiding the user to give the correct amount for individual patients. It is also capable of preventing over filling which could develop into a ‘heart failure’ situation.
Laparoscopic surgery results in smaller incisions and shorter length of stay as well as less preoperative pain. A pneumoperitoneum is formed by the surgical team in order to perform laparoscopic surgery. This is achieved by insufflating the abdomen with carbon dioxide (CO). The main haemodynamic changes expected would be a decrease in cardiac output/index and increases in mean arterial pressure and systemic vascular resistance, followed possibly by some partial restoration of cardiac output/index, yet blood pressure and heart rate may not change. This often results because of the interaction between increased abdominal pressure, neurohumoral responses and the absorption of CO. Different patients may respond to a greater or lesser degree depending on their age and any existing comorbidities as well as the current clinical situation.
Note: Dynamic predictors of fluid responsiveness (SVV and PPV) have been found to vary notably with pneumoperitoneum, and their performance in this condition is at best understudied. 
Deltex Medical suggests:
The clinician should be aware of any potential haemodynamic changes following abdominal insufflation, taking into account any underlying medical conditions as well as the current clinical situation and try to fluid optimise as early as possible during surgery ,  and ideally before pneumoperitoneum.
If there is a suspicion of hypovolaemia after abdominal insufflation, the user may consider that a fluid challenge should be given, but a new baseline of ODM+ results should be set and not compared to previous results. Fluid optimisation can be continued once the abdomen has been desufflated, if required.
It is suggested that if fluid optimisation has been done early, the patient may have less of a change in parameters during the pnuemoperitoneum.
In the Trendelenburg position, the body is laid flat on the back (supine) with the feet higher than the head by 15-30 degrees and is used in abdominal and gynaecological surgery for example to allow better access to the pelvic organs. With reverse Trendelenburg position, the body is tilted in the opposite direction. It was named after the German surgeon Friedrich Trendelenburg . It is not recommended for the treatment of hypovolemic shock .
There are however many positions that are used for patients in the operating theatre and are specific to surgery types. Each is likely to have different effects on the cardiovascular system. Knight  suggests that “Each position carries some degree of risk and this is magnified in the anaesthetised patient who cannot make others aware of compromised positions”
Some expected cardiovascular changes with Trendelenburg could be an increase in venous return to the heart because of a redistribution of pooled venous blood in the lower limbs. An increase in cardiac output may then occur but could partially offset some of the cardiovascular depressant effects of the anaesthetic techniques . Makic  summarises the expected haemodynamic responses to Trendelenburg positioning in hypotensive patients and include a slight increase in mean arterial pressure, no increase in preload, dilation of the right ventricle, decrease in right ventricular ejection fraction, decrease in cardiac output and an increase in systemic vascular resistance.
Deltex Medical suggests:
The clinician should be aware of any potential haemodynamic changes associated with positional changes, taking into account any underlying medical conditions as well as the current clinical situation. Fluid optimisation is ideally performed early during surgery ,  and where possible before any major position change. If there is a suspicion of hypovolaemia after change of position, the user may consider that a fluid challenge should be given, but a new baseline of ODM+ results should be set and not compared to previous results. Fluid optimisation can then be continued once the patient is returned to a supine position, if required.
Leather  describes the redistribution of blood flow when lumbar epidural anaesthesia is used and suggest that ODM+ may overestimate cardiac output during this time. They report “Lumbar epidural anaesthesia (LEA) increases blood flow to the lower body by sympathetic nerve block, and reduces
flow to the upper body by compensatory vasoconstriction caused by increased sympathetic nerve activity.”
Deltex Medical suggests:
Linear measurements (SD, FTc, PV etc) instead of volumetric parameters (SV, CO etc) can be used when a clinician is concerned about the ODM+ results in this situation. Linear measurements do not rely on the percent of cardiac output that flows to descending aorta nor on aortic size to estimate SV, CO etc. Use SD as a surrogate of SV since this correlates well with SV and can be used to observe the 10% change following a fluid challenge .
Deltex Medical Take Home Messages
The user should consider:
- The expected haemodynamic changes with pnuemoperitoneum and/or different patient positions and/or with the use of spinal anaesthesia.
- The age of the patient and any underlying comorbidities.
- The current clinical situation.
- Try to fluid optimise as early as possible.
- Monitor during surgery and only give fluid during change of position or pnuemoperitoneum if there is evidence of hypovolaemia and a clinical need.
- If fluid is given during pnumoperitoneum or when the position is changing, create new ODM+ parameter baselines and generally these data should not be compared periods outside of these i.e. do not ‘chase’ or compare previous values.
- Further fluid optimisation may be required towards the end of surgery when the patient is supine and desufflation of the abdomen has occurred.
- SD can be used instead of SV to manage fluid and/or vasoactive drugs if required.
1. Brandstrup, B., et al., Which goal for fluid therapy during colorectal surgery is followed by the best outcome: near-maximal stroke volume or zero fluid balance? Br J Anaesth, 2012. 109(2): p. 191-9.
2. Challand, C., et al., Randomized controlled trial of intraoperative goal-directed fluid therapy in aerobically fit and unfit patients having major colorectal surgery. Br J Anaesth, 2012. 108(1): p. 53-62.
6. Senagore, A.J., et al., Fluid management for laparoscopic colectomy: a prospective, randomized assessment of goal-directed administration of balanced salt solution or hetastarch coupled with an enhanced recovery program. Dis Colon Rectum, 2009. 52(12): p. 1935-40.
9. Høiseth LØ1, Hoff IE, Myre K, Landsverk SA, Kirkebøen KA. Dynamic variables of fluid responsiveness during pneumoperitoneum and laparoscopic surgery. Acta Anaesthesiol Scand. 2012 Jul;56(6):777-86.
14. Pillai, P., et al., A double-blind randomized controlled clinical trial to assess the effect of Doppler optimized intraoperative fluid management on outcome following radical cystectomy. J Urol, 2011. 6(6): p. 2201-6.