the potential bicarbonate. If the p

the potential bicarbonate. If the potential bicarbonate
was not calculated, the metabolic acidosis with high
AG combining with metabolic alkalosis would have
been missed and so would the TABD. In our findings,
before we calculated potential bicarbonate, there were
only 8 patients with TABD and the missing rate was
as high as 88.7% (63 out of 71 cases). This is even
worse than that due to non-calculation of AG (83.1%).
TABD is a serious metabolic derangement not to be
missed in critical care. Although treatment of TABD
should be directed to the underlying cause, timely
diagnosis of TABD allows us to understand more about
the factors contributing to the patients' conditions and
minimise treatment failure.
Among the 745 cases with ABD, DABD was the
commonest (N=525, 70.5%) with 371 (70.7%) of
them having metabolic acidosis combining with
respiratory alkalosis and 136 (25.9%) of them having
respiratory acidosis combining with metabolic acidosis.
Among SABD patients, metabolic acidosis was the
commonest (N=96, 64.4%). There were 71 patients
(9.5%) having TABD and most of them were of type
of respiratory alkalosis (N=63, 88.7%). These
suggested that majority of patients who suffered from
ABD could keep their plasma pH to nearly normal
level (7.35~7.45) by body compensation mechanism
in early phase. The reason that most SABD were
metabolic acidosis could be explained by hypoxaemia
and poor systemic perfusion which induced pathophysiological
injury with more acid production and
less acid removal. For TABD patients, the commonest
type was respiratory alkalosis which indicated that
respiratory compensatory mechanism would play a
major role.10 Some iatrogenic factors should be
considered in addition to body compensatory
mechanism. Among the 71 cases of TABD, nearly half
of them (N=36, 50.7%) suffered from TABD in the
initial stage and half of them (N=35, 49.3%) during
resuscitation. In general, taking glucocorticoid or
especially potassium wasting diuretic can induce
various types of ABD or exacerbate a pre-existing ABD
by inducing serum electrolyte imbalance. Some studies
suggested that inappropriate intake of potassium
wasting diuretic, inadequate potassium replacement,
excessive bicarbonate intake, prolonged gastrointestinal
suction, excessive gastric lavage and mechanical
ventilation are common iatrogenic factors inducing