Article Notes
- Nonetheless 'lower-risk' groups still suffered significant 30-day mortality rates, eg. 30-49 year olds (6%), women (18%), ASA 1-2 (12%), no-comorbidities (7%).
- Being asymptomatic at admission did not have a significant protective effect (22% vs 27% mortality).
- Dyspnoea and/or sputum on admission were the only symptoms associated with worse outcomes.
- 20% of patients suffered ARDS, with a 63% mortality rate.
- Although emergency surgery was higher risk, elective surgery still carried a 19% mortality rate. Even minor surgery resulted in a 16% mortality rate!
- Even obstetrics (2% mortality) and gynaecology (5%) demonstrated orders of magnitude-higher mortality than expected.
- There was no statistically significant difference between local, regional or general anaesthesia.
- Pulmonary embolus was only seen in 2% at 30 days and when present did not appear to impact mortality.
- Rubber and plastic bullets
- Beanbag rounds
- Shot pellets
- Baton rounds
- Arrest of individuals engaged in unlawful behaviour, such as throwing rocks and;
- Crowd dispersal in riot situations that threaten public safety."
- Physical distancing
- Face masks
- Eye protection
- Hypotension following spinal or combined spinal-epidural anaesthesia at caesarean section causes both maternal and fetal/neonatal adverse effects.
- Hypotension is frequent – vasopressors should be used routinely and preferably prophylactically.
- α‐agonist drugs are the most appropriate agents to treat or prevent hypotension following spinal anaesthesia. Although those with a small amount of β‐agonist activity may have the best profile (noradrenaline (norepinephrine), metaraminol), phenylephrine is currently recommended due to the amount of supporting data. Single‐dilution techniques, and/or prefilled syringes should be considered.
- Left lateral uterine displacement and intravenous (i.v.) colloid pre‐loading or crystalloid coloading, should be used in addition to vasopressors.
- The aim should be to maintain systolic arterial pressure (SAP) at ≥ 90% of an accurate baseline obtained before spinal anaesthesia, and avoid a decrease to < 80% baseline. We recommend a variable rate prophylactic infusion of phenylephrine using a syringe pump. This should be started at 25–50 μg.min−1 immediately after the intrathecal local anaesthetic injection, and titrated to blood pressure and pulse rate. Top‐up boluses may be required.
- Maternal heart rate can be used as a surrogate for cardiac output if the latter is not being monitored; both tachycardia and bradycardia should be avoided.
- When using an α‐agonist as the first‐line vasopressor, small doses of ephedrine are suitable to manage SAP < 90% of baseline combined with a low heart rate. For bradycardia with hypotension, an anticholinergic drug (glycopyrronium (glycopyrrolate) or atropine) may be required. Adrenaline (epinephrine) should be used for circulatory collapse.
- The use of smart pumps and double (two drug) vasopressor infusions can lead to greater cardiovascular stability than that achieved with physician‐controlled infusions.
- Women with pre‐eclampsia develop less hypotension after spinal anaesthesia than healthy women. Abrupt decreases in blood pressure are undesirable because of the potential for decreased uteroplacental blood flow. A prophylactic vasopressor infusion may not be required but, if used, should be started at a lower rate than for healthy women.
- Women with cardiac disease should be assessed on an individual basis; some conditions are best managed with phenylephrine (an arterial constrictor without positive inotropic effect), whereas others respond best to ephedrine (producing positive inotropic and chronotropic effect).
- Consent, particularly around providing inadequate pre-procedure information of the risk of neurological injury1 and the challenges, medical and legal, to achieving informed consent.
- Nerve injury and it's mechanisms: non-anaesthetic causes2, direct trauma, chemical, and compression (abscess, haematoma).
- Complication recognition & management means timely follow-up and assessment, and maintaining a high index of suspicion for abnormalities. Remember the 4 hour rule: blocks should be regressing 4 hours after the last dose.
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Noting from NAP3 the risk of nerve injury ranges from, temporary injury 1:1,000, prolonged (>6 months) 1:13,000, to severe (including paralysis) 1:250,000. ↩
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'Obstetric palsy' (pelvic nerve compression) estimated by Bromage as occurring in 1:3000 deliveries; arterial obstruction & ischaemia 1:15,000; AV malformations 1:20,000. A prospective French study found postpartum neuropathy in 0.3%, 84% were femoral, and 69% resolved at 6 weeks. ↩
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Although generally accepted as being at the L4/5 interspace, in up to 50% of people the intercristal line might be at or above L2/3! ↩
- Only 29% identified the space correctly.
- 68% indicated the space was lower than actual.
- 51% were one space out in their estimate.
- 15.5% two spaces.
- 1% three spaces.
- 0.5% four spaces.
This massively-multicenter (235 hospitals, 24 countries; mainly Europe & N. America) cohort study investigated post-operative morbidity and mortality in those with confirmed SARS-CoV-2 infection.
Why is this significant?
Early data suggested that COVID-19 patients who underwent even minor elective surgery suffered worse post-operative outcomes, particularly higher mortality.
This large cohort study confirms these concerns and will assist decision making around the timing of surgery for COVID-19 patients and the process for re-commencing elective surgery in communities hardest hit by the pandemic.
What did they do?
Over a 3 month period in early 2020 the researchers analysed 1,128 patients who underwent emergency (74%) or elective (25%) surgery across 24 countries. Patients diagnosed with COVID seven days pre-op or 30 days post-op were included, although the majority of patients (74%) had SARS-CoV-2 infection diagnosed post-operatively.
And they found?
30-day mortality was extremely high (24%).
Pulmonary complications (pneumonia, ARDS or unexpected post-op ventilation) were very common (51%) and were associated with an even higher mortality (38%; and 83% of all deaths).
Mortality was unsurprisingly associated with older age ≥ 70 years, male sex, ASA ≥ 3, emergency surgery, major surgery, and malignancy.
Other interesting observations...
Why such high post-operative COVID mortality?
The authors suggest this could be due to the combination of pro-inflammatory cytokine and immunosuppressive responses to surgery, and/or mechanical ventilation associated with general anaesthesia (although the later was not significantly associated with higher mortality).
Implications
Surgery for those with known or suspected COVID-19 should be avoided or delayed until after recovery from infection, as allowed by the underlying surgical pathology. When surgery cannot be delayed less-invasive surgery is preferable, and post-operative recovery should be closely monitored.
Keep in mind
Although RT-PCR testing was the main diagnostic test, in some settings clinical criteria (6%) and/or chest CT (7%) were instead used for diagnosis. Additionally, hospital data collection during a pandemic emergency carries higher risk of error, although this should not effect the broad validity of the research conclusions.
This systematic review out of Berkeley investigated data on death, injury and disability resulting from crowd control projectiles:
The researchers looked at published data from a 27 year period in the US, UK/N Ireland, Israel, Palestine, Switzerland, Turkey, Kashmir and Nepal.
The study was part of a larger effort from Physicians for Human Rights and the International Network of Civil Liberties Organizations.
What did they find?
Analysing 26 articles (mainly cohort studies) including 1,984 injured people, they identified 53 (3%) deaths and 300 (15%) permanently disabled. Half of total deaths and 83% of disabilities were due to head or neck strikes.
More than half (56%) of the deaths were from penetrative injuries, and 27% from chest or abdominal trauma.
The majority of permanent disability was vision loss, or abdominal injuries resulting in splenectomy or colostomy.
71% of survived injuries were severe, mostly to skin or extremities.
"Given their inherent inaccuracy, potential for misuse and associated health consequences of severe injury, disability and death, KIPs do not appear to be appropriate weapons for use in crowd-control settings."
Take-home
Although colloquially called 'non-lethal weapons', it would be more accurate to label kinetic impact projectiles (KIPs) as less-lethal weapons given the high risk of severe injury, permanent disability or even death.
"We identified only two basic contexts in which CCWs should be used in crowd-control settings:
Compounding issue...
Several articles highlighted the effect on morbidity of delays in accessing medical care due to police action and civil unrest.
"There is an urgent need to establish international guidelines on the use of CCWs to prevent unnecessary injury, disability and death, particularly in the use of operational models that avoid the use of weapons."
This important WHO-funded review and meta-analysis from Canada's COVID-19 SURGE group (Systematic Urgent Review Group Effort) looked at the effect of three non-pharmacological interventions on coronavirus transmission:
Why is this important?
The speed of both the global spread of SARS-CoV-2 and national responses has lead to a bundled-approach to public health interventions for which the evidence-base is still catching up. This review provides reassurance that the core recommendations are likely beneficial.
What did they do?
Reflecting the lack of data, the review group analysed research covering not just SARS-CoV-2, but also SARS and MERS, capturing 172 observational studies with over 25,000 patients in both community and healthcare settings.
What did they find?
Perhaps unsurprisingly (though reassuring!) physical distancing > 1 meter was associated with lower transmission risk (risk difference 95% CI -11.5 to -7.5%) with increasing protection as distance increased beyond 2 meters.
Face-masks were also associated with reduced transmission (risk difference 95% CI -14.3% to -15.9%, though with low certainty), as was eye protection (risk difference 95% CI -12.5% to -7.7%).
N95 masks were even more strongly associated with risk reduction, as was mask use in a health-care setting vs non-health-care. Both N95 and multi-layer surgical masks were more protective than single-layer masks.
Bottom-line?
Simple protective behavioural changes, namely physical distancing, face-mask use and eye protection, are associated with a significant risk reduction in coronavirus transmission.
“...recognize, as an aspect of health worker safety, the precautionary principle that reasonable action to reduce risk, such as the use of a fitted N95 respirator, need not await scientific certainty”.
Campbell (2006) SARS Commission final report
Keep in mind...
Most of the 172 studies reported on bundled interventions (ie. PPE and distancing) so multi-factor analysis was required to tease out the individual contributions to risk reduction. Randomised trials are still pending...
Although there is some evidence of different efficacy among commonly used vasopressors, translating this to clinically-significant outcome differences is still uncertain.
Singh's 2020 Bayesian network meta-analysis is the most comprehensive study to date investigating this issue. The researchers concluded that norepinephrine, metaraminol, and mephentermine showed the lowest probability of adverse neonatal acid-base effects, and ephedrine showed the greatest.
Previously phenylephrine infusion has been the consensus recommendation.
Nonetheless, other than ephedrine which should not be a first-choice pressor during Caesarean section, there is not enough evidence to strongly recommend one pressor over another. Clinical familiarity and institutional availability are probably the most important factors when choosing a vasopressor.
Why is this important?
Hypotension associated with spinal anaesthesia for Caesarean section is common. Increased interested over the past decade has resulted in some consensus recommending phenylephrine infusions, however there are few studies that directly compare this to other vasopressors.
What did Singh and team do?
By analysing 52 high-to-moderate quality RCTs and over 4,000 patients, Singh performed a Bayesian network meta-analysis to indirectly compare various vasopressors.
It's notable that umbilical artery base excess was used as the primary outcome, although other neonatal and maternal outcomes (nausea, vomiting, bradycardia) were secondarily assessed. Nonetheless, this study prioritised the fetal effects of hypotension management.
"We selected umbilical arterial BE as our primary outcome because it is thought to represent the effect of pronounced fetal hypoxaemia, anaerobic metabolism, and accumulation of non-volatile acids, that is the metabolic component of acidaemia."
Ok, what's a Bayesian network meta-analysis anyway?
A network meta-analysis compares trial interventions indirectly, when researchers are interested in a comparison between two factors (eg. use of metaraminol vs phenylephrine) that have not been directly compared by included RCTs (eg. a study comparing metaraminol vs ephedrine, and a study of phenylepherine vs ephedrine). A Bayesian NMA allows simultaneous comparison of multiple-arm trials, considering prior probability along with the likelihood of outcome rank between interventions.
A Bayesian NMA acknowledges the uncertainty of research conclusions and the probabilistic nature of clinical decision making.
Singh concluded...
Norepinephrine (noradrenaline), metaraminol, and mephentermine showed the lowest likelihood of adverse neonatal acid-base effects, and ephedrine the greatest.
"...norepinephrine, metaraminol, and mephentermine had the lowest probability of adversely affecting the fetal acid-base status as assessed by their effect on umbilical arterial base excess (probability rank order: norepinephrine > mephentermine > metaraminol > phenylephrine > ephedrine)."
When combined, there was a 66% probability that norepinephrine & mephentermine are the best agents for supporting umbilical a. BE.
There was a 66% probability that metaraminol is the best treatment for optimising umbilical artery pH, an 85% combined-probability that metaraminol & norepinephrine are best for umbilical a. pCO2, and 85% that they are the two best agents for avoiding maternal nausea and vomiting.
Be smart
Given the very nature of meta-analyses and the challenge of indirect comparison among agents from heterogenous studies, the conclusions are only suggestive of the benefits of phenylephrine alternatives. A large RCT is still needed! (And despite it's popularity in some countries, there are still only a small number of trials of metaraminol.)
Nevertheless, other than for bradycardia, ephedrine was most likely the worst for all outcomes, reinforcing past conclusions that there are better pressor choices.
Recommendations from the guidelines:
McCombe and Bogod report on their analysis of 55 medicolegal claims relating to obstetric neuraxial anaesthesia and analgesia.
Why is this important?
Not only is neurological injury the second most common reason for obstetric anaesthetic claims (behind inadequate regional anaesthesia resulting in pain during Caesarean section), the average claim cost is greater.
McCombe and Bogod provide a factful exploration of many of the causes of neurological complications.
Which themes emerged from their analysis?
Important reminders
The level of spinal cord termination varies a lot among individuals, as does the level of Tuffier's line3. Considering the inaccuracy of spinal level identification by anaesthetists, there is a lot of potential to place a needle higher than expected.
Bottom-line: the intrathecal space should be accessed at the lowest possible level, and "the L2/3 interspace should not be an option."
And never allow chlorhexidine to contaminate gloves, the sterile workspace or neuraxial equipment.
When anaesthetists were assessed on their ability to correctly identify a lumbar interspace level in 100 patients undergoing spinal MRI:
What did they do?
Chambers et al. compared ventilation parameters and respiratory complications in 104 children randomly allocated to ventilation with either a cuffed or non-cuffed ETT. They primarily investigated airway leak as measured by the difference between inspiratory and expiratory volumes.
And they found?
For both volume and pressure-controlled ventilation, leakage was lower for cuffed tubes than uncuffed. Notably leak was stable with cuffed tubes and PCV, but progressively increased over 30 minutes after intubation with an uncuffed tube.
Cuffed tubes required fewer intubations and changes, and resulted in fewer short-term complications (coughing, desaturation, hoarseness or sore throat).
Take-home message
Modern cuffed paediatric endotracheal tubes offer significant clinical advantages over uncuffed ETTs.