Exercise 10-1: Simulating Liquid Injection

A closed-circuit liquid anesthetic injection induction can be simulated with Gas Man.

SETUP

Parameter Selection Agent Isoflurane To simulate a closed-circuit, liquid¬- DEL (%) 0 injection anesthetic induction, adjust the Circuit Closed Gas Man parameters as shown. If Uptake FGF (L/min) 0.25 and Delivered show cost in the Picture Panel, click the “$” button on the toolbar VA (L/min) 4 (turn it off) to show Uptake and Delivered in CO (L/min) 5 L (liters of vapor). View (min) 15 Speed 5x Special none

To demonstrate a closed-circuit induction, click the Begin button, move the cursor and click on the anesthetic syringe icon four times over a period of a simulated minute or two. Each click will inject 0.5 mL of liquid isoflurane. The unit dose injected can be changed with the Anesthesia menu, by selecting Unit Dose.

Observation

Figure 10-1 shows the Picture and Graph of Exercise 10-1, demonstrating four injections of 0.5 ml liquid isoflurane into the breathing circuit.

Note in the Graph that inspired anesthetic tension reaches approximately 4% and then trails off to 1% near 7 minutes. Note the Update and Delivered quantities of anesthetic vapor. To see these expressed as cost, click the “$” button on the toolbar. The monetary value depends on the anesthetic cost, which can be changed via the Set Cost… command on the Anesthesia menu.

The values Gas Man offers (if they have not been changed at your site) are USA bottle volume and bottle cost as of March 5, 2008.

Exercise 10-2: Liquid Injection Can Produce Optimum Anesthesia

Closed-circuit liquid injection can produce optimum anesthesia, achieving and maintaining 1 MAC in the brain.

SETUP

Parameter Selection Agent Isoflurane To simulate closed-circuit induction and DEL (%) 0 maintenance at 1 MAC using liquid Circuit Closed injection, adjust the parameters as shown. FGF (L/min) 0.25 If Uptake and Delivered show cost in the Picture Panel, click the “$” button on the VA (L/min) 4 toolbar (turn it off) to show Uptake and CO (L/min) 5 Delivered in L (liters of vapor). View (min) 15 Speed 5x Special none

Make liquid injections by clicking on the syringe icon at appropriate times to produce anesthetic induction and maintenance similar to Exercise 72a, which demonstrated constant brain tension. Each time the inspired tension falls below the desired level, click on the syringe icon again.

Figure 10-2a displays the Picture and Graph of Exercise 10-2, shouting a simulated closed-circuit anesthetic with isoflurane.

You will note that about four injections, or 2 mL, of liquid anesthetic is required to elevate inspired tension and that 0.5 mL increments are then required with decreasing frequency. Try similar inductions for enflurane and halothane and observe results analogous to those shown in Figure 10-2a. Note the volumes delivered and taken up, and consider the potential monetary savings as well as the elegance of the technique. To see these expressed as cost, click the “$” button on the toolbar. The monetary value depends on the anesthetic cost, which can be changed via the Set Cost… command on the Anesthesia menu. The values Gas Man offers (if they have not been changed at your site) are USA bottle volume and bottle cost as of March 5, 2008.

Figure 10-2b displays the Picture and Graph of Exercise 10-2, showing a simulated closed-circuit anesthetic with enflurane.

Figure 10-2c displays the Picture and Graph of Exercise 10-2, showing a simulated closed-circuit anesthetic with halothane.