Implementation of goal-directed fluid therapy during hip revision arthroplasty
This matched cohort study aimed to determine whether a goal-directed fluid therapy (GDFT) intervention, delivered intraoperatively, would reduce post-operative morbidity in patients undergoing hip revision surgery. The study was a mix of prospective and retrospective design, and used invasive monitoring to determine cardiac stroke volume and adjust fluid management accordingly. They found that patients treated with their GDFT protocol had significantly less post-operative morbidity, as well as reduced stay in hospital and intensive-care.
Major surgery carries significant risk of morbidity. Given how many major procedures take place, optimising care to minimise risk has the potential to have a wide-ranging impact. The current picture is not unanimous, but some studies have shown that a protocol of GDFT may improve outcomes and reduce complications. The current data largely relate to major abdominal or vascular surgery, and little exists in the literature with direct relevance to orthopaedic surgery.
The authors prospectively enrolled 130 patients who were over 18 years old, and were scheduled for one of the following:
- Hip revision arthroplasty
- Hip revision with change of prosthesis
- Explantation of existing arthroplasty
- Post-Girdlestone procedure – undergoing new hip implantation.
These patients were then matched for age, ASA score and P-POSSUM score (see box below) to 130 of 258 patients from the preceding 2 years. Patients in both cohorts underwent general anaesthetic per local protocol, standard monitoring was used, with the control group receiving either non-invasive or invasive blood pressure (BP) monitoring at the anaesthetist’s discretion. For the GDFT group, invasive BP was standard, and stroke volume (SV) was calculated using a pulse contour method with pressure transducer. Repeated colloid boluses of 250 mL were given until stroke volume plateaued, with optimal SV recorded as the SV prior to the final fluid bolus. The trigger point for SV was recorded as 10% below the optimum, with the target SV remaining above that level. Ionotropes were used where further fluid boluses were insufficient, unless contraindicated.
P-POSSUM
The physiological and operative severity score for the enumeration of mortality and morbidity is a scoring tool to estimate operative risk. Originally developed in 1991 by Copeland et al., the modified ‘Portsmouth’ version was introduced in 1998 by Prytherch et al. The system uses multiple datapoints relating to the patient (e.g. age, ECG abnormalities, haemoglobin level) and the operation (e.g. expected blood loss volume, emergency or elective, operative complexity) to estimate surgical risk.
ASA score
Classification system developed by the American Society of Anaesthesiologists that broadly groups patients into 6 categories, from ASA I – healthy individual, to ASA VI – declared brain dead. It is less detailed than P-POSSUM, but is another tool to estimate operative risk.
The primary outcome was the proportion of patients developing post-operative complications during their hospital stay. Secondary outcomes included: post-operative need for vasopressors; specific complications; length of stay in recovery, intensive care; and hospital mortality.
Adherence to GDFT was generally good, with a review determining that the protocol was followed in 87.3% of patients. Post-operative morbidity was significantly lower in the GDFT cohort; 49.2% versus 66.9% (p=0.006). Length of stay was also shorter with GDFT (results expressed as median with 25th–75th percentiles); 9 (8–12) versus 11 (9–15) days (p=0.003). Post-operative intensive care stay was also significantly reduced; 400 min (207–825) versus 960 min (360–1210) (p<0.001); while there was no mortality difference detected.
In their discussion, the authors note the successful adherence to protocol of 87% as a particular strength of the study. Recent meta-analyses of randomised trials have suggested a 25–50% morbidity reduction, which is held up by the current findings. Of particular note was the improvement in the rate of cardiac adverse events with GDFT, despite a higher use of ionotropes – the authors suggest this may be related to the protocol avoiding their use in at-risk patients. The study is limited in the respect that causality cannot be established due to the study design, and the presence of confounders, however the paper provides ‘real-world’ data that show the practicality of careful fluid management.
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