Anesthesia & Co-existing Disease

Perioperative Acute Kidney Injury

An update article surveys the complex interplay of factors affecting kidney function in the perioperative period, discussing hemodynamics, fluids, diuretics, serum markers etc. “The Kidney Disease: Improving Global Outcomes guidelines suggest implementing preventive strategies in high-risk patients, which include optimization of hemodynamics, restoration of the circulating volume, institution of functional hemodynamic monitoring, and avoidance of nephrotoxic agents and hyperglycemia.”

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Another study links intraoperative oliguria to acute kidney injury, in contrast to previous work. This presents a conundrum in an ERAS era of restrictive fluid administration. Oliguria should should at least direct closer monitoring of renal function especially in those with risk factors, along with minimizing nephrotoxic sgents.

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Cricoid Pressure and Aspiration

A study throws doubt once again on the utility of cricoid pressure in preventing aspiration of gastric contents.

“The inclusion criteria were patients 18 years and older with a full stomach (<6 hours fasting) or the presence of at least 1 risk factor for pulmonary aspiration (emergency conditions, body mass index >30, previous gastric surgery [sleeve, bypass, or gastrectomy], ileus, early [<48 hours] postpartum, diabetic gastroparesia, gastroesophageal reflux, hiatus hernia, preoperative nausea/vomiting, and pain)”.

There was no difference in aspiration compared with a sham procedure but cricoid made intubation slower and more difficult. The authors caution that further study is needed in Obstetrics and outside the Operating Room.

However this study had a non-inferiority design that was underpowered with the low aspiration rates as well as defining a 50% difference threshold. It is unlikely to consign cricoid pressure to the history books but will perhaps confirm biases in the anti-cricoid camp!

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Post-Operative Atrial Fibrillation

Post-operative atrial fibrillation has been viewed as a transient or more benign phenomenon than non-valvular atrial fibrillation in chronic settings. This registry study showed that it occurred in 0.4% after non-cardiac surgery, more common after thoracic, vascular and abdominal surgery, and more likely in older patients with co-morbidities. After follow-up for some 3 years, the rate of thromboembolism was similar to those with non-valvular atrial fibrillation.

The authors recommend reconsideration of guidelines for anticoagulation in these patients at risk of thromboembolism and stroke.

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Anticoagulants and antiplateles in hip fracture surgery

Delay in hip fracture surgery can increase mortality (link ).

A Scottish Consensus statement on the management of patients on anticoagulants (and antiplatelet agents) presenting for hip fracture surgery incorporates current knowledge and views on when to proceed and how to expedite anticoagulant reversal with Vitamin K and/or Prothrombin Complex Concentrate, as well as antiplatelet agent considerations. Caution may also be needed with neuraxial techniques in such patients.

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Post-Operative Anemia Management

An international consensus on the management of post-operative anemia encourages a more proactive strategy to complement more restrictive blood transfusion practices.

All patients having major surgery with pre-operative anemia or significant blood loss need Hemoglobin assessment for 1-3 days along with Ferritin measurement. “iron deficiency should be defined by ferritin concentration < 100 μg.l−1, ferritin < 100–300 μg.l−1 and transferrin saturation < 20%, or reticulocyte haemoglobin content < 28 pg”.

Intravenous Iron is favoured as more effective, and off-label Erythropoiesis stimulating agents should be considered. A full exposition of the subject is at the link.

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Resuming Beta Blockers Post-op

For those taking chronic beta-blockers in non-cardiothoracic, non-vascular surgery, resumption on post op day 1 reduces the risk of Atrial Fibrillation (although no evidence supported resuming earlier, on surgery day).

Chronic medications frequently fall through the cracks in the peri-operative setting and efforts to resume these agents in the absence of contraindications should be encouraged. Thromboembolic events could occur even in the brief peri-operative setting.

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Antiplatelet Duration for Stent after MI

Current recommendations specify 6 months dual antiplatelet therapy (DAPT) after PCI in stable ischemic heart disease and 12 months after acute coronary syndromes. This new study looked at DAPT after STEMI and found: “Limiting DAPT duration to six months in patients with STEMI that are event-free results in a non-inferior clinical outcome, as assessed by a patient-oriented composite clinical endpoint versus 12 months of DAPT”. Aspirin was continued after this 6 month period.

While the guidelines remain, these findings are reassuring in that a shorter duration of DAPT may be reasonable especially insofar as surgical procedures are impacted often by delaying for 12 months.

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Prediction of Disability Free Survival

This sub-study sought to evaluate the 6 Minute Walk Test prediction of disability free survival. Of the risk assessment tools analysed, the Duke Activity Status Index was the most predictive of  disability free survival. “The 6MWT was safe and comparable with cardiopulmonary exercise testing for all predictive assessments. Future research should aim to determine the optimal 6MWT distance thresholds for risk prediction”.

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See previous study also: link