1. Postoperative intravenous morphine titration
F. Aubrun, J.-X. Mazoit, B. Riou 
British Journal of Anaesthesia 
Volume 108, Issue 2, Pages (February 2012)
DOI: /bja/aer458
Copyright © 2012 The Author(s) Terms and Conditions

2. Fig 1
Simulations of morphine concentration in the central plasma compartment (Cp, green) and in the effect compartment (Ce, blue) after various schemes of administration (a–c). (a) Because morphine kinetics are linear, three successive i.v. boluses of 3 mg at 5 min interval lead to a three times higher Ce when compared with a single 3 mg injection. (b) Cp and Ce after i.m. injections of 10 mg morphine every 4 h. Because the kinetics are linear, steady state is not attained before the third injection. In addition, the delay of action after injection is important (time to maximum Ce=2 h) and the peak-and-valley phenomenon of large magnitude. (c) The administration of three titration doses of 3 mg at 5 min interval, followed by 1 mg by patient-controlled analgesia every 10 min from 20 to 90 min after initiation of titration and every 20 min after the 90th min. Ce 5 min after the third i.v. injection (15 min after initiation) is the same as Ce obtained 4.5 h after the first i.m. injection. Note the different time scale. Simulations have been performed with the data from Mazoit and colleagues.13
British Journal of Anaesthesia  , DOI: ( /bja/aer458)
Copyright © 2012 The Author(s) Terms and Conditions

3. Fig 2
Simulations of Ce obtained after i.v. injection of alfentanil/remifentanil (blue), sufentanil/fentanyl (green), and morphine (pink). Units are arbitrarily normalized by the area under the Ce–time curve. The time to Cemax, the peak concentration in the effect compartment, is 2, 6, and 20 min, respectively, for alfentanil/remifentanil, sufentanil/fentanyl, and morphine, respectively. The relative duration of analgesia, the time for which Ce exceeds 80% of its maximum value,5 is 2.5, 7.5, and 78 min for alfentanil/remifentanil, sufentanil/fentanyl, and morphine, respectively. Simulations have been performed with the data from Mazoit and colleagues13 and Lötsch and colleagues.12 t1/2ke0=1.65 h, ka=1 h−1 for morphine, and t1/2ke0=1 min for alfentanil/remifentanil and 6 min for sufentanil/fentanyl.
British Journal of Anaesthesia  , DOI: ( /bja/aer458)
Copyright © 2012 The Author(s) Terms and Conditions

4. Fig 3
Protocol for i.v. morphine titration in adults. VAS, visual analogue scale; RR, respiratory rate; AP, arterial pressure; HR, heart rate.
British Journal of Anaesthesia  , DOI: ( /bja/aer458)
Copyright © 2012 The Author(s) Terms and Conditions

5. Fig 4
Relationship between the VAS score [mean (sd)] and time (interval between two boluses was 5 min) during morphine titration and thus pain relief. (a) Global population. (b) Patients separated into groups according to the number of boluses needed to obtain pain relief.9
British Journal of Anaesthesia  , DOI: ( /bja/aer458)
Copyright © 2012 The Author(s) Terms and Conditions

6. Fig 5
Comparison of postoperative morphine requirement in young (n=224) and elderly (n=105, ≥70 yr) patients in the PACU (i.v. morphine titration) and in the ward (s.c. administration). Data are mean (sem). *P<0.05 vs young patients. From Aubrun and colleagues.32
British Journal of Anaesthesia  , DOI: ( /bja/aer458)
Copyright © 2012 The Author(s) Terms and Conditions