**3. Infiltration techniques evolution**

#### **3.1 The dry technique**

Fournier described the dry technique of liposuction in 1983, however, due to the significant volume of blood loss in the lipoaspirate reaching 20-40%, the technique has fallen out of favour [18].

#### **3.2 The wet technique**

Illouz introduced this technique and it included infiltrating 200–300 cc of infusate fluid regardless of the volume to be aspirated. The blood loss in the lipoaspirate was reduced to 8-10% [4, 5].

The wet technique evolved by introducing the addition of epinephrine further reducing the blood loss in the infranatant of the lipoaspirate as a result of the vasoconstriction of vessels, this blood loss was 4-8% [19].

#### **3.3 The superwet technique**

The superwet technique meant injecting 1 cc of infusion to 1.5 cc of lipoaspirate; Fodor 1986 described this technique. The technique meant the blood loss in the lipoaspirate was reduced to ~1% [20].

#### **3.4 The tumescent technique**

Klein, a dermatologist, introduced the tumescent technique, which lead to significant advances in performing liposuction and later liposcultpure including high definition body contouring under local anaesthetic as day cases. The lipocrit was low at 1%, which is not unlike the superwet technique. The tumescent technique was popularised in 1990s [9].

The tumescent infiltration technique uses the skin turgor and it colour change to white as end points on the volume injected in the area of liposculpture, allowing for larger volumes to be removed than other wetting solutions. The infusate to lipoaspirate is usually 2-3:1. It uses a mixture of 50 cc of 1% Lidocaine infiltrated in 1 litre

of normal saline, 1 cc of 1:1000 adrenaline with 10 cc of 8.4% sodium bicarbonate solution, the later helps reduce the pain at infiltration. The pH of normal saline is 5; adding bicarbonate makes it less acidic and leaves less ionised Lidocaine outside the cell for absorption [21].

This means large volume of dilute Lidocaine with concentration of up to 35 mg/kg can be injected into the fat. This is much higher than the toxic doses when injecting undiluted Lidocaine mixture at 7 mg/kg. An added advantage of the tumescent infiltration is decreased need for intravenous fluid replacement [21].

It is of grave importance to consider the estimated volume to be removed when performing aspiration of fat. Hence, in our experience although we use the tumescent mixture of infusate; however, we tend to use infusate to lipoaspirate ration of 1:1, i.e. the superwet technique.

In our experience using the superwet technique equates to less fluid load, lower risks of local anaesthetic toxicity at diluted concentrations of Lidocaine not exceeding 35 mg/kg and limiting the infusate to no more than 4-5 litre for lipoaspirate of 4 litres.

When infusing large volumes and aspirating large volumes for example 3 litres or more one must replace for each ml of aspirated fat ~2 mls of fluid in the first 24 hours. For example in a case of 3 litres injected for 3 litres aspirated; it is estimated that ~20% of the injected fluid will be removed with the lipoaspirate. This will leave 2.4 litres in the extracellular space warranting a total fluid volume replacement of 3.6 litres in the first 24 hours.

It is important to stress that in such large volume lipoaspiration, urine output should be monitored for the first 24 hours, adding safety to the patient management.
