Blood loss calculation
The amount of blood lost by the patient during surgery should be calculated, as it can affect how the patient recovers and may mean that additional treatments, such as a blood transfusion, are needed. If the VS or anaesthetist is concerned about blood loss during surgery, it is often the job of the circulating nurse to calculate the amount of blood lost.
For blood loss calculations, the used swabs are weighed to determine the weight of blood they contain; 1 g is equivalent to 1 ml of blood. Weighing swabs has been shown to be an accurate way to calculate blood loss. The steps for performing a blood loss calculation are as follows.
1. Estimate the patient ' s total blood volume. This is usually approximately 66 ml / kg for cats and 88 ml / kg for dogs.
2. Weigh and count all the used swabs.
3. Calculate the approximate dry weight of the swabs by multiplying the number of swabs used by the weight of a dry swab.
4. Subtract the approximate dry weight of the swabs used from the weight of the used swabs. This will give the weight of blood in the swabs( in g), which is equal to the volume( in ml).
5. Measure the volume of fluid in the suction canister. If possible, add all of the flush fluid from the table to the volume in the canister to help with the calculation in step 8.
6. Estimate the amount of blood on the floor and drapes. This step can be difficult, as accurately estimating fluid volumes is challenging.
7. To give the total fluid volume, add the total volume of blood in the swabs to the volume in the suction canister and on the table, and the volume on the drapes and floor.
8. Subtract the volume of flush used during the surgery from the total fluid volume. This will give the total blood loss in ml.
9. Calculate the percentage of blood loss as follows [ 11 ]: total blood lost ÷ estimated total blood volume × 100.
Role of the scrub nurse
The scrub nurse is a sterile team member who can assist the VS in several ways during surgery. Their role can include assisting with draping, passing surgical instruments, retracting tissues, and taking extra surgical materials or equipment from the circulating nurse.
Preparing the kit trolley
One of the scrub nurse ' s roles is to prepare the surgical instruments on a sterile surface, such as a Mayo trolley covered with a sterile drape, ready for surgery. This can be done before the patient enters the theatre, allowing the surgery to begin as quickly as possible and minimising the time during which the patient is anaesthetised.
All instruments and other materials should be laid out neatly and logically. Any sharps, such as scalpels, should be placed on a sharps pad to minimise the risk of piercing through the sterile drape and breaking sterility. The scrub nurse should also perform a swab and sharps count in preparation for the surgical safety checklist( as discussed earlier).
Draping the patient
Once the surgical site has received the final preparation for surgery, the patient can be draped ready for surgery. The scrub nurse can assist the VS by passing or placing the drapes. There are several types of drapes:
• Reusable cotton drapes
• Non-reusable drapes
• Plain drapes
• Fenestrated drapes.
A comparison of reusable and non-reusable drapes is shown in Table 4.
Table 4. Comparison of reusable and non-reusable drapes.
Reusable drape Cheaper
More porous( may lead to strikethrough and a break in sterility)
Quality deteriorates with repeated use – can lead to loose threads getting into the surgical site
More environmentally friendly
Non-reusable drape More expensive Water repellent
Quality remains consistent as a new drape is always used
Less environmentally friendly
Depending on the type of drape, a different technique may be required. When using plain drapes, a fourquarter draping technique should be used. Each drape is placed to create a‘ window’ around the surgical site( Figure 5, page 57). The drapes are secured to the patient using the adhesive on the drape or towel clips, such as Backhaus towel clips.
56 Veterinary Nursing Journal