Article Notes
- Safety concerns regarding respiratory depression cannot be ignored, and because managing this relies upon staff vigilance, increased PCA use may conversely lead to a normalisation of risk and institutional complacency, rather than safety improvement.
- Analgesia is still inferior to epidural, even if maternal satisfaction is comparable.
- Technique acceptability might not be as good in communities with high pre-existing epidural use.
- Post-operative complications occur in 25-40% of patients, making this the most important focus for improving perioperative outcomes.
- Failure to rescue is a common problem, and few postoperative patients actually experience sudden deterioration, instead hindsight shows a slow and steady decline leading to the critical event that generates an emergency response.
- Remote monitoring uses medical-grade biosensors wirelessly linked to a central receiver, integrated with an electronic patient record, allowing patients free movement.
- The handful of currently available systems monitor combinations of heart rate ± variability, ECG, respiratory rate, pulse oximetry, blood pressure, temperature, posture and activity.
- Continuous monitoring may then be integrated with systems that calculate an Early Warning Score, automatically notify staff of early deterioration, or in more advanced future systems, allow prediction of deterioration.
- Although feasible, all current systems suffer from practical and technical issues that can limit their sensitivity and specificity.
- Evidence of benefit is still very patchy, although data suggests that automated notification of deterioration leads to earlier responses by treating teams, with small interventions, reducing the burden on rapid response / MET systems.
- No actual morbidity or mortality outcome data is yet available.
- They note that there is no gold standard to measure frailty, although there are many attempts to reliably identify and measure frailty across its many domains.
Nonetheless frailty is strongly associated with perioperative morbidity and mortality.
One proposed indicator of physical frailty is the presence of three of Fried's five factors: unintentional weight loss; grip strength weakness; exhaustion; slow walking speed; and low physical activity.
Frailty is "...a multidimensional state of reduced physiological reserve, resulting in increased vulnerability to stressors, decreased resilience, and loss of adaptive capacity."
Prehabilitation aims to increase physiological reserve through pre-operative intervention, including but not limited to exercise, nutrition and inspiratory muscle training.
- β-lactam allergy, particularly penicillin allergy is the most common perioperative patient-reported sensitivity, in up to 35% of patients.
- Unneccessary switching to non-β-lactams for surgical prophylaxis is not cost-free, and is contributing to the rise of c. difficile and vancomycin-resistant Enterococcus (VRE).
Patient history of penicillin allergy is of variable quality, and often does not allow the allergy to be ruled-out.
Step 1 – differentiate drug side effects from allergy. Isolated nausea, vomiting or diarrhoea are usually side effects.
Step 2 – identify the type of hypersensitivity.
- Most drug reactions are Type 4 (T-cell mediated), delayed from 2 hours to days after exposure. Mostly benign cutaneous symptoms (eg. rash) that do not necessarily require avoiding future β-lactam exposure, except in the case of Stevens-Johnson syndrome.
- Type 1 (IgE-mediated) hypersensitivities are immediate (minutes to 2 hours) but less common, causing urticaria, angioedema and/or anaphylaxis. Future exposure should be avoided.
- Type 2 (cytotoxic) and Type 3 (immune complex) are much less common, and present with more serious, though delayed, reactions (days to weeks).
Take home: Mild symptoms (eg. rash developing more than 2h after exposure) probably do not require β-lactam avoidance. If there is a history of moderate or severe reaction, then avoiding all β-lactams is wise.
Of interest: Although R1 side-chain similarity is the main contributor to penicillin-cephalosporin cross-reactivity, importantly, 1st generation cephazolin has a different R1 side-chain and has been reported to not cross-react. Other cephalosporins share side-chains with specific penicillins.
Finally, stop giving IV test doses. It makes no sense from a safety point of view and offers no useful information.
Why should you care?
Not only is venous cannulation a common procedure, but so is resultant thrombophlebitis – occurring in up to 75% of patients. This has important morbidity, patient-experience and economic consequences.
What does this study add?
Although many risk factors have been identified (insertion sterility, location, access technique, drug use, micro-particles, etc.), Villa and friends investigated whether in-line filters would reduce phlebitis incidence.
This modest, single-center trial randomized surgical patients between in-line filter (for 96 hours) or standard line, before anesthesia induction. Filter user reduced thrombophlebitis 13-fold at 48 hours, and at 96 hours sustained potency of 50% more of the cannulae.
What sort of filters did they use?
They used an 11 cm2 positively-charged 0.2 µm filter for fluid and most drugs, a 4.5 cm2 1.2 µm filter for propofol infusions, and a positively-charged 1.65 cm2 0.2 µm for opioid infusions.
The filters did slow gravity-fed infusion rates as they aged, however this was not clinically significant when using a peristaltic pump.
The take-home...
We should be better stewards of our patient's IV access. For short-term access <48h focus should be on technique and sterility, but for access needed for 48h or longer, an inline filter offers significant benefit with limited downside.
Daniel Jolley
Chris Tan
Accurately identifying the cricothyroid membrane is foundational for front-of-neck rescue of airway misadventure. Yet the very patients who are at risk of a cannot intubate, cannot oxygenate scenario (eg. obese, neck pathology) are also likely to make identifying the cricothyroid membrane (CTM) difficult.
Naveed and co. compared the accuracy of CTM palpation to ultrasound in a single-blinded randomized trial of 223 patients, with poorly defined landmarks, undergoing CT neck.
The ultrasound group showed a 10-time greater success in identifying the CTM (correct within 5 mm of actual; 81% vs 8%), along with a 5-times smaller mean distance from actual to estimated, than did the palpation group.
So what's the take home?
Given the wide-availability of ultrasound and it's acceptability to patients, any pre-induction marking of the CTM in an anticipated difficult airway should employ neck ultrasound in all but the most obviously-palpable necks.
In an emergent CICO situation, neck ultrasound likely has utility, though at the potential cost of procedural complexity and delay.
Daniel Jolley
The more I think about these results, the more interesting it is.
Reducing instrumental delivery rate is a real benefit for women, though is this due to avoiding epidurals or some other difference? How do we balance the issues of safety, analgesia, perineal trauma and maternal satisfaction? And how do we communicate this to labouring women in a meaningful way?
Questions questions...
Daniel Jolley
What did they do?
Wilson et al randomized 401 laboring women across multiple centers to either remifentanil PCA or pethidine/meperidine IM, then compared the progression of these women to labour epidural.
On the surface... this might appear disingenuous, as it compares remifentanil PCA to widely-shown-to-be-ineffective parenteral pethidine – rather than to the gold standard labour epidural. But it's also a study of how the technique might practically be used in the real world.
What they found
Women with remifentanil PCA progressed half as often to require epidural analgesia than those receiving pethidine (19% vs 41%).
Though it's one of the secondary findings that is most interesting: the remifentanil group were less likely to need instrumental delivery (15% vs 26%).
But don't get carried away
Despite the demonstrated superiority of remi PCA to pethidine, the technique is not without it's issues:
And finally... why are we so eager to do away with the labour epidural? Serious complications are very uncommon to rare, the technique is widely acceptable to women, and it is more effective than any other modality.
Is this change driven by the needs of pregnant women, or the health system's limited resources?
Daniel Jolley
What did they do?
Using a randmoized, double-blind crossover study, Fong et al anaesthetized eight male volunteers twice with 1.2% isoflurane for 1 hour, after propofol induction. In the final 10 minutes subjects were randomized to IV caffeine or placebo. No opioids were administered.
Receiving IV caffeine hastened emergence by over 40%, as measured by BIS and psychomotor testing.
Return of gag reflex was used as the marker of emergence, although time to emergence was consistent with eye opening and BIS.
How much caffeine did they give?!?
15 mg/kg of caffeine citrate, equivalent to 7.5 mg/kg of base caffeine – the same caffeine as in two large cups of coffee for a 70 kg male.
Come on, surely this isn't that important?
Although the mean 7 min difference may not appear clinically significant, especially when using more modern volatiles, this study is a good proof of concept of how caffeine may be a useful clinical tool when faced with delayed emergence after anesthesia and for patients at greatest risk of persistent psychomotor depression post-anesthesia, such as the elderly.
Daniel Jolley
Boer, Touw and Loer describe the concept of continuous, remote vital sign monitoring and the current level of evidence for it's proposed benefit.
We know that...
Continuous remote vital sign monitoring on surgical wards may improve early recognition of deterioration.
So, any real evidence?
Be cautious...
While the hope is that remote monitoring can improve patient safety, it could disingenuously be used to justify reduced ward staffing and hospital stay length by normalizing the risk of our current postoperative harm status quo.
Daniel Jolley
A useful review of the role of rehabilitation in frail patients by Milder, Pillinger and Kam.
Final word: although attractive, prehab has not yet been shown to improve outcomes in frail patients, though this is likely due to the absence of high quality studies.
Daniel Jolley
Daniel Jolley