Month: January 2019

Preoperative Cardiac Optimization

Another Anaesthesia review discusses the approach to preoperative cardiac risk stratification, hypertension, heart failure, murmurs, beta-blockers and other medication management, and implantable electronic cardiac devices.

Also discussed is the role of preoperative investigation such as EKG, CXR, and Echocardiography, as well as serial monitoring of Troponins and BNP. Some evidence for exercise therapy as a preoperative cardiac prehabilitation is reviewed.

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Emergency Laparotomy Preoptimization

Anaesthesia journal continues its preoptimization series. More than half of emergency laparotomies are over 70 years old and have an ASA status > 3. Bowel obstrction, adhesions, peritonitis, perforation, among others comprise a large proportion. The preoptimization window is smaller for emergency surgery.

Timely antibiotics, standard or geared for sepsis are needed. Balanced crystalloids for fluid sequestration in the bowel are preferred over normal saline for better renal outcome. Starches are out of fashion for similar renal adverse effects and mortality in sepsis, gelatins reported as potential allergic reactions, and Albumin not of proven benefit. Concomitant distributive shock from sepsis may require vasopressors like Norepinephrine, and CVP (and newer cardiac output and volume assessment tools) may be needed. Electrolytes, especially Potassium may need replacement.

Acute hemorrhage necessitates blood rather than excessive fluids. Cardiovascular medications need review and management, and nephrotoxic agents eliminated due to the high incidence of renal injury in this scenario.

Nutritional supplementation should begin early. Diabetes needs insulin infusion usually, but overly tight control is now discouraged, aiming for around 8mmol/L.

The National Emergency Laparotomy Audit (NELA)  2016-2017 identified delays, and timely Operating Room transfer is important. (It also flagged early antibiotics, presence of senior attending physicians and failure to refer for geriatric assessment. Risk assessment was recommended using tools such as P‐POSSUM model or the NELA risk prediction model).

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OR Fires

Another (gated) review seeks to bring attention to the issue of Operating Room fires. It reviews the “fire triangle” of ignition, fuel and oxidizer; the contribution and risks of such factors as electrosurgery, laser, drills, fibreoptic light sources, defibrillators, alcohol skin prep, intestinal gas, drapes and oxygen.

Oxygen is one of the key modifiable factors and advice is to maintain FiO2 below 30%. Over 80% of all OR fires are in surgery on the head, neck and upper chest and a similar percentage under sedation, where local oxygen concentrations can easily increase with nasal cannula flow above (or even less with draping) 4l/min. A lethal combination of oxygen, drapes and alcohol based preps can develop waiting for the cautery to spark a fire, particularly lethal near the patient airway.

Should a fire occur, recommendations are to stop the flow of all airway gases, disconnect the breathing circuit, remove tracheal tubes in airway fires and irrigate with saline, and remove burning materials, extinguish the fire and restore room air breathing.

Fire risk should be included in checklists at briefing and/or timeouts.

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A (free!) guideline is also available from the FDA here

Intrathecal Fentanyl for Cesarean Delivery

This study validates the common use of Fentanyl in spinal anesthesia for Cesarean delivery. It reduces the need for intraoperative supplemental analgesia, reduces nausea and vomiting, with longer time for postoperative first analgesia request, and similar benefits were observed when added to Bupivacaine-Morphine spinals.

There was no difference in conversion to GA, hypotension, the onset of sensory block, or the duration of motor block. The only downside was an increase in pruritus.

The study was a systematic review and meta-analysis.

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Dementia and Perioperative Care

New guidelines published in Anaesthesia deal with the perioperative care of patients with dementia. Concepts such as post-operative cognitive disorder and delirium are also discussed and their risk factors. Emphasis is on assessment, legal implications, communication and liaison with family and patients, as well as non-disorienting environments. The unproven relationship between anesthesia and dementia is discussed, as well as judicious use of anesthesia and sedatives, although again little conclusive evidence is available to choose general or regional anesthesia. The potential benefits of brain monitoring and/or regional cerebral oxygenation is reviewed. Frailty, comorbidities and polypharmacy are common issues to be managed.

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Early Postoperative Desaturation and Discharge Outcome

A large retrospective study reviewed oxygen desaturation < 90% in the 10mins after extubation in non-cardiac surgery. It was associated with higher odds of being discharged to a nursing facility, a higher risk of respiratory, renal and cardiovascular complications, as well as increased duration of hospital stay, postoperative intensive care unit admission frequency, and cost. Associated risk factors included high intraoperative FiO2, low FiO2 before extubation, high Neostigmine dose, and higher intraoperative long-acting opioid administration.

The authors note: There was substantial provider variability between anaesthetists in the incidence of postoperative desaturation unexplained by patient‐ and procedure‐related factors. This highlights the difficulty in interpreting retrospective studies, but should at least prompt reflecting on extubation readiness criteria as well as the role of oxygen saturation.

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Medical and Health News Weekly

Children still receive inadequate pain relief link

There are economic consequences for patients and families after cardiac and stroke events in terms of loss of employment and earnings link

GoFundMe crowdfunding is going to bogus and useless alternative treatments link

Genetic testing popularity now extends to individualized diet and weight loss – totally unproven use for such tests link

Draft of upcoming Canadian Food Guide to emphasize fruits, vegetables and whole grains, include plant-based protein, and upset the meat, dairy, processed food and beverage industry link

After decades of progress, US seeing a dramatic rise in sexually transmitted infections link

Transdermal treatment was the safest type of hormone replacement therapy when risk of venous thromboembolism was assessed link

Common medications like statins, calcium channel blockers and biguanides associated with reduced psychiatric hospitalization in those with mental illness, not necessarily causal link

Eat at least 25-30g fibre daily to decrease cardiovascular, diabetic, hypertensive diseases, cholesterol, cancers…but not much to recommend low-carb link

Influenza taking a serious toll on children link

Drug overdose deaths from prescription and illicit drugs in middle aged women sharply increasing link

Residual Neuromuscular Blockade

The incidence of residual neuromuscular blockade after anesthesia is, in short, too high and this retrospective study sought to establish its relationship to hospital costs. While there was not an independent association with hospital cost, there was a greater odds of ICU admission, along with a trend towards increased hospital length of stay.

The findings continue to support rigorous quantitative monitoring of neuromuscular function during anesthesia and adequate reversal to a minimum Train-of-Four of 0.9, and probably more optimally 1.

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Sepsis-Associated Acute Kidney Injury

The BMJ provides a comprehensive article on Sepsis-associated acute kidney injury (AKI). It discusses risk factors such as advanced age, chronic kidney disease, cardiovascular disease, diabetes, and liver disease. Review of sepsis definitions and kidney injury scores like RIFLE, AKIN and KDIGO are discussed. Markers beyond creatinine are surveyed, like albuminuria, urine microscopy for casts, NGAL etc.

As well as early detection, early resuscitation is important, with balanced electrolyte solutions rather than 0.9% Saline; controversy exists as to the Surviving Sepsis recommendations of 20mL or more per kg fluid, and the potential negative effects of excess fluid are highlighted.

Vasopressor choices to maintain mean arterial pressure include Norepinephrine and Vasopressin. Dopamine and Phenylephrine have not achieved comparable results or safety. Angiotensin II may have promise in future studies.

Mechanical ventilation, although unavoidable often, may increase AKI risk from multiple mechanisms like changes in intrathoracic pressure, reducing venous return, cardiac output, and renal perfusion, as well as neurohormonal and inflammatory pathways.

Pharmacological treatments for AKI are largely preliminary. Renal Replacememt therapy should not begin too early from recent trials, optimal dose being 20-25mL/kg/hour. Removal of toxins via hemoperfusion has not been proven effective. Nephrotoxic agents should be avoided (NSAIDS, contrast, Hydroxyethyl Starch).

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Preoperative Nutrition Optimization

Anaesthesia continues its preoperative optimization articles.

The frequent occurrence of malnutrition in pre-operative patients results in functional impairment, decreased immune defence, delayed wound healing and organ dysfunction. It increases infectious and non-infectious complications, length of stay, cost, readmission, and mortality. Muscle loss and fatty infiltration occur from disease, stress responses and treatment.

Evidence exists that correcting malnutrition can decrease complications and improve outcome. Assessing malnutrition may involve BMI, weight loss and dietary history and albumin measurement. Tools such as the Duke Peri‐operative Malnutrition Score, and Peri‐Operative Enhancement pathway are discussed. References are also provided to guidelines from the European Society for Clinical Nutrition and Metabolism, American Society of Parenteral Enteral Nutrition, and the American Society for Enhanced Recovery with Peri‐operative Quality Initiative.

Treatment involves protein supplementation and Vitamin D, omega-3 fatty acids, as well as immunonutrition with glutamine, arginine and cysteine. The authors advise a more equal distribution of protein through the day in synergy with exercise.

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