In addition to standard anaesthetic monitoring, true core temperature monitoring is highly recommended, ideally with an oesophageal temperature probe (if the prone position is used, a rectal temperature probe may be placed after turning prone). The length of the procedure predisposes patients to intraoperative hypothermia [7, 8, 29] with its attendant risks, and active patient warming and temperature monitoring is mandatory; forced air or equivalent warming should be applied to as much of the body surface area as possible whilst maintaining surgical access. This can be more difficult to achieve in the supine position as continued access to the perineum is desired by the surgeon and the legs are more difficult to warm in the lithotomy position. Intravenous fluids should be warmed, as should surgical irrigation which can amount to many tens of litres. Despite these measures mild intraoperative hypothermia is common; however, occasional patients may become pyrexial, either due to overly effective warming or due to release of organisms or toxins from the stone, and may even require cooling measures. Core temperature monitoring gives effective warning of these problems.

Fortunately major blood loss during PNL is not common, although the large proportion of cardiac output taken by the kidneys emphasises the potential for major haemorrhage on occasion. Venous access should be of sufficiently large bore to cope with this, especially as patient access to allow insertion of additional cannulae may be difficult. Serum samples should have been saved preoperatively to allow provision of cross-matched blood in a timely fashion should it be required. Blood loss is difficult to assess due to the large volumes of irrigating fluid in which lost blood is diluted. Modern point-of-care instruments allow rapid assessment of haemoglobin concentration from capillary blood obtained by fingerprick which may help guide the requirement for intraoperative transfusion. Due to the risk of significant intraoperative fluid shifts, including occult or occasional brisk bleeding and involving the inability to monitor urine output, central venous pressure monitoring may be considered in patients with significant heart failure to avoid fluid overload, haemorrhagic anaemia and intraoperative ischaemia.

Mention has already been made of the possibility of intraoperative sepsis, and it is helpful if the organisms responsible for an individual patient’s previous episodes of urosepsis, and their antibiotic sensitivities, are known in order to allow the provision of rational prophylactic and therapeutic antibiotic treatments intraoperatively and postoperatively.