The Editor-in-Chief would like to correct some errors in the above published article that have been pointed out by readers of BJA Education, and provide further explanation.
The elastance curve depicted in Figure 1 relates to the changes in ICP in response to an intracranial mass that is increasing in volume. According to the Monro-Kellie doctrine, an increase in the volume of one intracranial compartment will lead to a rise in ICP unless it is matched by an equal reduction in the volume of another compartment. Since the total intracranial volume is constant, the volume depicted on the X-axis is effectively the volume (of blood, CSF, and brain tissue) displaced and could be labelled as such. In fact the shape of the curve reflects the sequential displacement of venous blood and CSF; decreased CSF production and increased reabsorption; and the effects of arterial vasoconstriction. ICP remains relatively constant (i.e. the curve is flat until these mechanisms have become exhausted); arterial blood and then brain tissue are displaced with a rapid increase in ICP in response to further small increases in the volume of the intracranial mass. In the text this was described as an exponential increase, though this is not correct as the relationship is not a mathematical exponential function. The Editors also recognise that the precise relationship of the curve is also affected by other factors (e.g. posterior fossa lesions, age, and other physiological factors) and so the curve should not have included numerical values and units on the axes.
In Table 1, the recommended doses and volumes of mannitol and hypertonic saline were incorrect.1 The corrected table is presented below. The Editorial team would like to apologise for these errors and any inconvenience caused.
1. Brain Trauma Foundation. Guidelines for the management of severe TBI, 4th Edn. Available from https://braintrauma.org/guidelines/guidelines-for-the-management-of-severe-tbi-4th-ed#/
Jonathan Thompson
Editor-in-Chief
BJA Education
Table 1 (Revised) Comparison of different concentrations of hypertonic saline available for clinical use, and mannitol as a 10% and 20% preparation
| Solution | Sodium concentration (mmol L−1) | Osmolarity (mOsmol L−1) | Equiosmolar dose ml (275 mOsmol) | Dose (ml kg−1) for 80 kg person | Recommended dose in intracranial hypertension |
|---|---|---|---|---|---|
| NaCl 0.9% | 154 | 308 | 892 | 11.0 | N/A |
| Ringer’s lactate | 130 | 275 | 1000 | 12.5 | N/A |
| Saline 1.7% | 291 | 582 | 472 | 5.9 | |
| Saline 3% | 513 | 1027 | 268 | 3–6 ml kg−1=240–480 ml | 3–6 ml kg−1 |
| Saline 5% | 856 | 1711 | 161 | 2 | 1–2 ml kg−1 |
| Saline 7.2%/HES 6% (200/0.6) | 1232 | 2464 | 112 | 1.4 | |
| 7.5% saline | 1283 | 2566 | 107 | 1.3 | 1–2 ml kg−1 |
| Saline 7.5%/dextran 70 6% | 1283 | 2568 | 107 | 1.3 | |
| Saline 10% | 1712 | 3424 | 80 | 1 | |
| Saline 23% | 4004 | 8008 | 34 | 0.43 | |
| Saline 30% | 5000 | 10,000 | 27.5 | 0.34 | |
| Mannitol 10% (0.1 g ml−1) | 549 | 502 | 2.5–10 ml kg−1=200–800 ml | 0.25–1 g kg−1 over 30–60 min | |
| Mannitol 20% (0.2 g ml−1) | 1098 | 251 | 1.25–5 ml kg−1=100–400 ml | 0.25–1 g kg−1 over 30–60 min |