Kreienbühl L, Elia N, Pfeil-Beun E et al.
Anesthesia & Analgesia 2018: 127 (4): 873-880.
Aim and Hypothesis
- Objective: to establish the relative safety of propofol-based patient-controlled sedation (PCS) as an alternative to clinician-controlled sedation (CCS) for provision of sedation in moderately invasive procedures.
- Hypothesis: that PCS may provide a safer method of sedation control as compared to CCS, and in particular for the particular outcomes outlined below.
Primary Outcomes
- Desaturations (with and without oxygen supplement)
- Arterial hypotension – SBP of <90 mm Hg or <80 mm Hg or a drop of >30% from baseline
- Bradycardia – PR <60bpm,<40 bpm, or a decrease of >10% from baseline
- Rescue interventions – chin lift maneuvers, bag-mask ventilation, sympathomimetic drugs for hypotension,and atropine for bradycardia
Secondary Outcomes
- Total propofol administration
- Risk of over-sedation
- Operator satisfaction
- Patient satisfaction
Background
- Functionally comparable to PCA
- Implemented extensively in Scandinavia, Switzerland, Australia, etc.
- Also commonplace in dentistry
- Typical agent combination propofol +/- alfentanil; as opposed to fast-acting benzodiazepines
- Patient autonomy hypothesised to also confer physiological placebo as feeling of control
Cohort and Study Inclusion
- Procedures included – ERCPs, ECSW lithotripsies, Colonoscopies, Cataract surgery
- Total 13 RCTs included in meta-analysis, 1103 patients
- Patient cohort
- ASA I – III
- Age range 36 to 68
- BMI 23.4 to 29.6
Statistical Analysis
- Use of cumulative z-curve analysis in order to determine either:
- Definitive statistical significance/insignificance given sufficient cumulative data (optimal information size) has been reached
- The likelihood of statistical significance being achieved with further accumulation of data if the optimal information size has not yet been reached
Results
(* denotes significant or potentially significant result)
Desaturation
- Cohort: 11 trials, 929 patients – short of optimal information size (1152)
- Net result: 6.9% PCS patients vs 9.6% CCS patients
- Significance:
- RR 0.74 (98% CI, 0.35 to 1.56)
- Cumulative Z-curve entered futility as of 2010 Mandel et al study addition, so unlikely benefit from further studies
Arterial hypotension*
- Cohort: 6 trials, 688 patients – short of optimal information size (957)
- Net result: 6.6% PCS patients vs 11.5% CCS patients
- Significance:
- RR 0.56 (98% CI, 0.34 to 0.93)
- Cumulative Z-curve not entered conclusive benefit boundary after 688, would benefit from further data
Bradycardias
- Cohort: 4 trials, 451 patients – short of optimal information size (2319)
- Net result: 5.1% PCS patients vs 5.0% CCS patients
- Significance
- RR 0.86 (98% CI, 0.35 to 2.09)
- Generally inconclusive due to lack of data pool as compared to optimal information size
Rescue therapies*
- Cohort: 11 trials, 931 patients – over optimal information size (713)
- Net result: 6.5% PCS patients vs 15.4% CCS patients
- Significance
- RR 0.45 (98% CI, 0.25 to 0.81)
- Statistically conclusive, cumulative Z-curve over optimum information line so further studies unlikely to alter this result
Secondary outcomes
- Total propofol dose: weighted mean difference (WMD) -21.8mg in PCS vs CCS (98% CI, -44.3 to 0.73); not significant
- Over-sedation*: RR 0.37 (98% CI, 0.21 – 0.63); significant
- Operator satisfaction: WMD -0.18cm (98% CI, -0.46 to 0.11); not significant
- Patient satisfaction: WMD -0.05cm (98% CI, -0.49 to 0.39); not significant
Limitations
- Lack of standardised parameters across studies to define outcome thresholds (i.e. different definitions/leniencies for hypotension, over-sedation, etc.)
- No physiological extremes included
- Lack of data exposition regarding different specific sedation regimes i.e. dose-response or agent-response correlations
Strengths
- Highly demanding statistical scrutiny, i.e. CI 98% rather than 95% due to end-point refinement
- Z curve analysis to qualify validity of cumulative data as well as practical implementation of future data
- Large scope and heterogeneity of data compiled
- Study defines potential for further research in this area
Discussion
- Little effort has been made to implement patient controlled sedation in appropriate settings, where studies have shown that it is at least as effective as CCS in providing adequate sedation
- We must differentiate scenarios in which sedation plays a beneficial role for the patient alone, and when it also benefits the clinician in terms of procedural ease
- Should we consider the way we deliver sedation more so than the actual agents we are using for the purpose?
- Would we lose expertise in managing patient sedation if PCS became the mainstay, and how much would that matter?
Summary by Dr L Alvarez Belon. Journal Club Meeting 11 October 2018.
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