European journal of anaesthesiology
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Meta Analysis Comparative Study
Deep vs. moderate neuromuscular blockade during laparoscopic surgery: A systematic review and meta-analysis.
Previous studies have reported that deep neuromuscular block (posttetanic-count 1 to 2 twitches) improves surgical conditions during laparoscopy compared with moderate block (train-of-four count: 1 to 2 twitches). However, comparisons of surgical conditions were made using different scales and assessment intervals with variable results. ⋯ Deep block was associated with excellent or good surgical rating more frequently than moderate block. However, this finding was not consistent on subgroup analyses based on frequencies of assessment of surgical conditions and abdominal pressure. Further studies are required to address the heterogeneity and power shortage demonstrated by the trial sequential analysis.
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Comparative Study Observational Study
Intra-operative cutaneous temperature monitoring with zero-heat-flux technique (3M SpotOn) in comparison with oesophageal and arterial temperature: A prospective observational study.
Continuous monitoring of core temperature is essential during major surgery as a way of improving patient safety. Oesophageal probes or specific arterial catheters are invasive methods used in this setting. A new noninvasive device based on zero-heat-flux (ZHF) technique (SpotOn) seems promising but has been poorly investigated during rapid core temperature changes (RCTC). ⋯ A SpotOn sensor using the ZHF method seems reliable for core temperature monitoring during abdominal surgery when variations in core temperature are slow rather than rapid.
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Mechanisms of peri-operative ischaemic optic neuropathy remain poorly understood. Both specific pre-operative and intra-operative factors have been examined by retrospective studies, but no animal model currently exists. ⋯ An injury partly resembling human ischaemic optic neuropathy can be produced in rats by combining haemodilution and head-down tilt. Significant functional changes were also present with haemodilution alone. Future studies with this partial optic nerve injury may enable understanding of mechanisms of peri-operative ischaemic optic neuropathy and could help discover preventive or treatment strategies.
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Why is this important?
First, because it identifies new novel risk factors for residual neuromuscular block (experienced surgeon, non-CRNA anesthesia provider...) and secondly, because the subtext reveals the lengths our specialty goes to avoid simply monitoring using qualitative NMB monitoring (TOFR)!
What did they find?
Rudolph et al. created a REsidual neuromuscular block Prediction Score (REPS) using Massachusetts General PACU data, applying covariate analysis to identify 10 risk factors, some more surprising than others:
- Hepatic failure
- Neurological disease
- High-neostigmine dose > 60 mcg/kg
- Metastatic solid tumour
- Female sex
- Less than 120 min between NMBD administration and extubation
- Aminosteroid NMBD
- BMI more than 35
- Absence of nurse anaesthetist (CRNA)
- Having an experienced surgeon
Be smart:
These risk factors might suggest patients who need more careful monitoring, but you will probably be better off just using qualitative monitoring routinely. The utility of REPS itself is only modest with NPV & PPVs of 85% each.
The other takeaway is that rNMB is still demonstratably common, occurring in 20% of this cohort!
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This meta-analysis (unsurprisingly) confirms that pre-operative troponin levels are post-operatively associated with both major adverse cardiac events and mortality risk.
This sounds obvious, why should we care?
First, there's a difference between evidence and that vague feeling we call common-sense that a disproportionate number of our clinical decisions are based upon.
Surgical patients are getting older and sicker. We need better tools for risk stratifying patients before surgery to improve perioperative planning. Most importantly (though not exclusively) reliably identifying biomarkers for risk allows closer postoperative surveillance and monitoring – which may alter outcomes.
Why troponin?
We already know that troponin I and T are markers of cardiac damage, and unlike brain natriuretic peptide (BNP), troponin assays are readily available in most healthcare settings.
Ok, you convinced me... what did they find?
Analysing 10 studies totally 10,371 patients, they found an association between preoperative troponin elevation and MACE (OR 6.9), and short-term & long-term mortality (OR 4.2 & 2.5). Note though that the confidence intervals were quite wide.
There's always a but... the included studies were all observational in nature, used a variety of troponin assays, and the results were quite heterogenous across the 10. Most importantly, even assuming troponin is an accurate preop risk marker, we don't yet know whether that knowledge will allow us to alter outcomes for these patients.
summary