Anesthesia Management

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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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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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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Perioperative Methadone for Analgesia

While Methadone is well known for its role in medication assisted treatment for substance use disorders, its long duration of analgesia has perhaps been under-appreciated for surgical analgesia. In addition to its opioid action it has anti-hyperalgesic and anti-allodynic properties through NMDA antagonism, and Serotonin-Norepinephrine re-uptake inhibition. Doses generally given are 20mg or 0.2mg/kg. Studies indicate 24 hours or more analgesia with reduced need for supplemental analgesia.

Studies are ongoing as to its safety in different at-risk populations, e.g. coexisting medications, older, frail, cardiorespiratory disease, OSA, but this APSF article provides a great primer on Methadone in the perioperative period.

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WHO Surgical Safety Checklist In Emergency Laparotomy

A global cohort study explored the use and impact of the WHO Surgical Safety Checklist in emergency laparotomy. Once again, the findings were striking in that checklist use in emergency laparotomy was associated with a significantly lower perioperative mortality rate. Checklist use in low‐Human Development Index (HDI) countries was half that in high‐HDI countries.

The authors importantly note that the association with lower mortality “is likely to reflect broader health system differences that prioritize safe and effective surgical care, yet the checklist plays an important part”. It focuses a team on better communication, collaboration, empowerment and behavioural changes.

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