580 CHAPTER 16 Urological surgery and equipment

Fluid balance and management of shock in the surgical patient

Daily fluid requirement

This can be calculated according to patient weight:

•For the first 10 kg: 100 mL/kg per 24 hours (= 1000 mL)

•For the next 10 kg (i.e., 10–20 kg): 50 mL/kg per 24 hours (= 500 mL)

•For every kg above 20 kg: 20 mL/kg per 24 hours (= 1000 mL for a patient weighing 70 kg).

Thus, for every 24 hours, a 70 kg adult will require 1000 mL for their first 10 kg of weight, plus 500 mL for their next 10 kg of weight, and 1000 mL for their last 50 kg of weight = total 24-hour fluid requirement, 2500 mL.

Daily sodium requirement is ~100 mmol, and for potassium, 770 mmol. Thus, a standard 24-hour fluid regimen is 2 L of 5% dextrose + 1 L of normal saline (equivalent to about 150 mmol Na+), with 20 mmol K+ for every liter of infused fluid.

Fluid losses from drains or nasogastric aspirate are similar in composition to plasma and should be replaced principally with normal saline.

Shock due to blood loss

Inadequate organ perfusion and tissue oxygenation occur. The causes are hypovolemia, cardiogenic, septic, anaphylactic, and neurogenic. The most common cause in the surgical patient is hypovolemia due to blood and other fluid loss. Hemorrhage is an acute loss of circulating blood volume.

Hemorrhagic shock may be classified as follows:

•Class I: up to 750 mL of blood loss (15% of blood volume); normal pulse rate (PR), respiratory rate (RR), blood pressure (BP), urine output, and mental status

•Class II: 750–1500 mL (15–30% of blood volume); PR >100; decreased pulse pressure due to increased diastolic pressure; RR 20–30; urinary output 20–30 mL/hr

•Class III: 1500–2000 mL (30–40% of blood volume); PR >120; decreased BP and pulse pressure due to decreased systolic pressure; RR 30–40; urine output 5–15 mL/hr; confusion

•Class IV: >2000 mL (>40% of blood volume); PR >140; decreased pulse pressure and BP; RR >35; urine output <5 mL/hr; cold, clammy skin

Management

•Remember ABC (Airway, Breathing, Circulation): 100% oxygen to improve tissue oxygenation

•ECG, cardiac monitor, pulse oximetry

•Insert two short and wide IV cannulae in the antecubital fossa (e.g., 16G). A central venous line may be required.

•Infuse 1 L of warm Hartmann’s solution or, if severe hemorrhage, then start a colloid instead. Aim for a urinary output of 0.5 mL/kg/hr and maintenance of blood pressure.

FLUID BALANCE AND MANAGEMENT OF SHOCK 581

•Check complete blood count (CBC), coagulation screen, and cardiac enzymes.

•Cross-match 6 units of blood.

•Obtain arterial blood gases (ABG) to assess oxygenation and pH.

Obvious and excessive blood loss may be seen from drains, but drains can also block, so assume there is covert bleeding if there is a tachycardia (and low blood pressure).

If this regimen fails to stabilize pulse and blood pressure, return the patient to the operating room for exploratory surgery.

Further reading

American College of Surgeons Committee on Trauma (1999). Advanced Trauma Life Support for Doctors—Student Course Manual, 6th Edition.

582 CHAPTER 16 Urological surgery and equipment

Patient safety in the operating room

It is a fundamental part of safe surgical practice to cross-check that the following have been done prior to starting an operation or procedure. The process of cross-checking should be done with another member of staff (time out).

•Patient identification. Confirm that you are operating on the right patient by a process of active identification (i.e., ask the patient their name, date of birth, and their address to confirm that you are talking to the correct patient).

•Ensure you are doing the correct procedure and on the correct side by cross-checking with the notes and X-rays. For lateralized procedures (e.g., nephrectomy, PCNL), the correct side of the

operation should be confirmed by cross-checking with the X-rays and with the X-ray report, as well as referring to the notes. Where it is possible for the sides of an IVP to be incorrectly labeled, this cannot happen with a CT scan, where the location of the liver (right side) and the spleen (left side) provide confirmation of what side is what. In addition, the patient should have the correct side mark on their body by the operating surgical team in the holding area.

•Check that appropriate antibiotic prophylaxis has been given.

•Check that DVT prophylaxis has been administered (e.g., heparin, AK-TEDS, intermittent pneumatic compression boots).

•Ensure that blood is available, if appropriate.

•The patient should be safely and securely positioned on the operating table—pressure points are padded, not touching metal (to avoid diathermy burns), body straps are securely in place.

Develop an approach to operating that involves members of your team. Listen to the opinions of staff members who are junior to you. They may sometimes be able to identify errors that are not obvious to you.

Cultivate the respect of the recovery room staff. They may express concern about a patient under their care—listen to their concerns, take them seriously, and, if all is well, reassure them.

It does no harm to your patients or to your reputation for you to develop the habit of visiting every patient in the recovery room in order to check that all is well. You may be able to identify a problem before it has developed into a crisis, and, at the very least, you will gain a reputation for being a caring surgeon.

TRANSURETHRAL RESECTION (TUR) SYNDROME 583

Transurethral resection (TUR) syndrome

TUR syndrome arises from the infusion of a large volume of hypotonic irrigating solution into the circulation during endoscopic procedures (e.g., TURP, TURBT, PCNL). It occurs in 0.5% of TURPs.

Pathophysiology

Biochemical, hemodynamic, and neurological disturbances occur:

•Dilutional hyponatremia is the most important—and serious—factor leading to the symptoms and signs. The serum sodium usually has to fall to <125 mmol/L before the patient becomes unwell.

•Hypertension is due to fluid overload.

•Visual disturbances may be due to the fact that glycine is a neurotransmitter in the retina.

Diagnosis—symptoms, signs, and tests

These include confusion, nausea, vomiting, hypertension, bradycardia and visual disturbances, and seizures. If the patient is awake (spinal anesthesia), they may report visual disturbances (e.g., flashing lights).

Preventing development of TUR syndrome and definitive treatment

Use a continuous irrigating cystoscope (provides low-pressure irrigation), limit resection time, avoid aggressive resection near the capsule, and reduce the height of the irrigant solution.1

For prolonged procedures, where a greater degree of fluid absorption may occur, measure serum Na and give 20–40 mg of IV furosemide to start off-loading the excess fluid that has been absorbed. If the serum sodium comes back as being normal, you will have done little harm by giving the furosemide, but if it comes back at <125mmol/L, you will have started treatment already and thereby may have prevented the development of severe TUR syndrome.

Techniques for measuring fluid overload (not commonly done)

•Weighing machines can be added to the ordinary operating table.2

•Adding a little alcohol to the irrigating fluid and constantly monitoring the expired air with a breathalyser3 allows an estimation of the volume of excess fluid that has been absorbed.

1 Madsen PO, Naber KG (1973). The importance of the pressure in the prostatic fossa and absorption of irrigating fluid during transurethral resection of the prostate. J Urol 109:446–452.

2 Coppinger SW, Lewis CA, Milroy EJG (1995). A method of measuring fluid balance during transurethral resection of the prostate. Br J Urol 76:66–72.

3 Hahn RG (1993). Ethanol monitoring of extravascular absorption of irrigating fluid. Br J Urol 72:766–769.