6 research outputs found
The use of volume kinetics as a method to optimise fluid therapy
Background: This thesis presents a new application of pharmacokinetic
analysis, usually applied to drugs, to the disposition of intravenous
fluid. One-volume and two-volume models were developed and non-linear
regression was used to characterise the blood marker dilution versus
time, relative to the administered dose of intravenous fluid. The
pharmacokinetic, or rather volume kinetic, behaviour of fluids were
examined under different conditions. This model makes it possible for the
scientist to distinguish between expendable and non-expandable fluid
spaces in the body.
Methods: I: Eight healthy male volunteers were given Ringer's solution 25
ml kg-1, dextran 5 ml kg-1 and hypertonic saline 3 ml kg-1 for 30 minutes
during three different sessions. Plasma dilution was measured by three
different indices: blood haemoglobin, blood water and serum albun-lin.
The results were fitted to the volume Idnetic models. II: Fifteen healthy
male volunteers and six female volunteers were given Ringer's solution 25
ml kg-1 for 30 minutes (males) and over 30, 45 and 80 min (females). The
plasma dilution following various other infusion rates were simulated by
computer using the mean values of the kinetic analysis. Ill: The volume
kinetics of patients with a standardized trauma were studied. Ten
patients suffering from a umhantefic fracture were compared to healthy
controls. A fluid load of 12.5 ml kg-1 of Ringer's solution was given the
day after closed reduction and surgical repair. Bioelectrical impedance
values were measured to establish the fluid balance status. IV: The
effect of endotoxin on the volume kinetic parameters was examined. Ten
rabbits, which were their own controls, were used. In the first session
the rabbits were given a fluid load of 25 ml kg-'. In the next session
the rabbits were given the same fluid load but were preinjected with
endotoxins 20 µg kg-1. V: To investigate whether fluid therapy changes
the prerequisites for the development of oedema, four intravenous
infusions of Ringer's solution of 25 n-d kg-'were given over 15 or 30
niin in a randoniised cross-over study to 10 healthy male volunteers.
Results: I: Ringer'solution gave the most pronounced dilution. Blood
haemoglobin and blood water correlated closely. The two-volume space
model was statistically justified especially when Ringer's solution was
given. II: Nomograms for obtaining and maintains a certain plasma
dilution for both men and women could be constructed. III: The results
show that the elimination of fluid is slower in a trauma population. The
bioelectrical impedance analysis showed that the extracellular fluid
space and the total body water volumes did not differ between the two
groups at the time of the study. IV: The dilution of the plasma volume
had a markedly variable volume effect after endotoxin had been given. The
expanded fluid space was smaller after the injection of endotoxin. V: The
volume kinetics analysis shows that the elimination rate was higher when
another infusion had been given earlier on the same day. The size of the
primary fluid space was slightly larger during the 15-min infusions.
Conclusions: It is possible to use a volume kinetic model to study the
behaviour of intravenous fluids. The dilution profiles have an
exponential appearance and could therefore be handled according to
pharmacokinetic principles
Post-anaesthesia pulmonary complications after use of muscle relaxants (POPULAR): a multicentre, prospective observational study
Background Results from retrospective studies suggest that use of neuromuscular blocking agents during general
anaesthesia might be linked to postoperative pulmonary complications. We therefore aimed to assess whether the use
of neuromuscular blocking agents is associated with postoperative pulmonary complications.
Methods We did a multicentre, prospective observational cohort study. Patients were recruited from 211 hospitals in
28 European countries. We included patients (aged ≥18 years) who received general anaesthesia for any in-hospital
procedure except cardiac surgery. Patient characteristics, surgical and anaesthetic details, and chart review at discharge
were prospectively collected over 2 weeks. Additionally, each patient underwent postoperative physical examination
within 3 days of surgery to check for adverse pulmonary events. The study outcome was the incidence of postoperative
pulmonary complications from the end of surgery up to postoperative day 28. Logistic regression analyses were
adjusted for surgical factors and patients’ preoperative physical status, providing adjusted odds ratios (ORadj) and
adjusted absolute risk reduction (ARRadj). This study is registered with ClinicalTrials.gov, number NCT01865513.
Findings Between June 16, 2014, and April 29, 2015, data from 22803 patients were collected. The use of neuromuscular
blocking agents was associated with an increased incidence of postoperative pulmonary complications in patients who
had undergone general anaesthesia (1658 [7·6%] of 21694); ORadj 1·86, 95% CI 1·53–2·26; ARRadj –4·4%, 95% CI
–5·5 to –3·2). Only 2·3% of high-risk surgical patients and those with adverse respiratory profiles were anaesthetised
without neuromuscular blocking agents. The use of neuromuscular monitoring (ORadj 1·31, 95% CI 1·15–1·49;
ARRadj –2·6%, 95% CI –3·9 to –1·4) and the administration of reversal agents (1·23, 1·07–1·41; –1·9%, –3·2 to –0·7)
were not associated with a decreased risk of postoperative pulmonary complications. Neither the choice of sugammadex
instead of neostigmine for reversal (ORadj 1·03, 95% CI 0·85–1·25; ARRadj –0·3%, 95% CI –2·4 to 1·5) nor extubation at
a train-of-four ratio of 0·9 or more (1·03, 0·82–1·31; –0·4%, –3·5 to 2·2) was associated with better pulmonary outcomes.
Interpretation We showed that the use of neuromuscular blocking drugs in general anaesthesia is associated with an
increased risk of postoperative pulmonary complications. Anaesthetists must balance the potential benefits of
neuromuscular blockade against the increased risk of postoperative pulmonary complications