Article Notes
Why is this interesting?
Lidocaine/lignocaine has been increasingly used intra- and perioperatively as an analgesic adjunct, with further research suggesting a potential neuroprotective effect. Cognitive decline is a common problem following cardiac surgery (40-50%), with lidocaine potentially offering a simple and safe intervention to reduce this complication. Past studies have showed conflicting results.
What did they do?
This Duke University team randomized 478 cardiac surgery patients across multiple centres to lidocaine intraoperatively (1 mg/kg bolus then decreasing infusions across 2.9 / 1.5 / 0.6 mg/kg/h over 48 hours) or blinded control. Cognitive function was assessed at 6 weeks and 1 year.
They found...
No difference in cognitive deficit between lidocaine infusion and saline control at either 6 weeks or 1 year.
Be smart
Intravenous lidocaine infusion remains relatively safe, practical and is still likely a useful analgesic adjunct. Similar to magnesium, which has been shown to be neuroprotective in premature infants but not adult cardiac patients, the problem for lidocaine may well be context rather than physiological benefit itself.
Daniel Jolley
Relevance?
Although anti-hypertension therapies are the domain of primary care physicians, because of their widespread use they are common medications for hospital patients. Previous studies have shown that nocturnal anti-hypertensive dosing improves BP control, although have not addressed major cardiac outcomes.
This 10-year, large, multicenter RCT demonstrates benefit of evening medication dosing that has implications perioperatively.
The study...
The Hygia Project randomised 19,084 patients (x̄=61y 56%♂ 34%♀) to take their anti-hypertensive medications (≥1) either at bed-time or on awakening. Patients were followed for a median 6.3 years, routinely using 48h ambulatory BP monitoring at each follow-up review.
They found that...
Patients taking anti-hypertensives in the evening experienced better BP control and 45% lower rates of major cardiovascular outcomes, including CVD death, infarct, coronary revascularisation, heart failure and stroke.
Interestingly the progressive decline in sleeping SBP during the study was the strongest predictor of cardiovascular risk, stronger than traditional risk markers such as age, gender, DM, CKD, cholesterol or even smoking!
Practice changing?
This is a significant finding from a large, high-quality study. It confirms the benefits of nocturnal dosing, also likely (though unconfirmed) to have intraoperative and perioperative benefits compared with morning dosing.
Daniel Jolley
Why the fuss?
Acute renal injury is a common post-operative complication among high-risk patients and after major surgery, particularly cardiac and major vascular surgery, as is relevant to this study. The clinical relevance of ischaemic preconditioning continues to be controversial.
Even mild post-operative acute kidney injury (AKI) is associated with a wide range of poor perioperative outcomes, and current interventions have struggled to reduce such risk.
What is remote ischaemic preconditioning (RIPC)?
In an effort to protect an at-risk end organ from ischaemia (eg. heart, brain, kidneys), RIPC cyclically induces ischaemia in a remote site (typically an arm using an NIBP cuff). This activates physiological protective mechanisms against hypoxia and reperfusion injury in the target organ. It is cheap, easy and safe.
RIPC as a technique is based upon Murray’s 1986 observations of dog LAD arteries.
Although remote ischaemic (pre)conditioning has been demonstrated in animal models, human studies have been contradictory.
What was done...
This Shanghai research team randomised 130 patients undergoing open aortic arch replacement to receive either remote ischaemic preconditioning (4x 5-min-up 5-min-down) or sham preconditioning.
They found...
Fewer patients demonstrated renal injury at 7 days in the treatment group (55% vs 74%, ARR 95% CI 2-35%), in addition to shortening mechanical ventilation duration (18 vs 25 hours).
Practice changing? No
Although this study has shown a marked reduction in AKI in a uniquely very-high-risk group, as a sole small single-centered study it can barely be applied to the actual study population, let alone generalised to other high-risk groups.
Even when AKI in the control group was a massive 74%, the confidence interval for absolute risk reduction (2-35%) is so wide as to cast doubt on the credibility of this result.
Go deeper:
Meybohm (NEJM 2015), Hausenloy (NEJM 2015), and Menting (Cochrane 2017) failed to show any significant renoprotective effect from RIC in other high-risk groups.
Daniel Jolley
Why is this relevant?
Sore throat following endotracheal intubation is common (reported in up to 68%), and along with postoperative nausea & vomiting, negatively impacts postoperative well-being.
Small studies have previously suggested that IV dexamethasone reduces sore throat due to intubation. It is thought this occurs by reducing mucosal inflammation at the point of tracheal cuff contact, the presumed aetiology of the majority of post-ETT sore throat.
Kuriyama and Maeda conducted a systematic review and meta-analysis of 15 RCTs totalling 1,849 patients.
And they found?
Preoperative dexamethasone IV (~4-10 mg across the studies) reduced the incidence of sore throat by almost 40% (RR 95% CI 0.51-0.75) and mean severity by 1.1 (SMD 95% CI 1.8-0.3).
Take-home...
Given the established effectiveness of preoperative dexamethasone to safely reduce post-operative nausea and vomiting, this meta-analysis affirms another important indication for the routine use of dexamethasone in intubated patients who do not have contraindications to steroid use.
Daniel Jolley