Anesthesia Management

Safe Use Of High-Flow Nasal Oxygen (HFNO)

The Anesthesia Patient Safety Foundation provide an excellent overview of the popular and expanding use of High Flow Nasal Oxygen (HFNO), devices which are in many cases supplanting BIPAP, and  used to provide apneic ventilation during intubation, as well as post extubation and weaning from ventilation. This review also adds some caution, in particular the danger of fire, and contraindications.

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Post-Dural Puncture Headache

A small study based on chart reviews limits the findings of this study which should be tested in future controlled studies. Nonetheless an interesting approach to postdural puncture headache was performed in the form of a topical sphenopalatine ganglion block and compared to the standard epidural blood patch. This ganglion block is being tested for migraine and other headaches but remains investigational.  (These topical blocks are usually described as simply placing local anesthetic soaked swabs along the floor of the nose until reaching and stopping at the nasopharynx and left there for 10mins or so, more recently with syringes attached to nasal catheter).

These authors found a faster headache resolution at 30 and 60 minutes with sphenopalatine block.

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Graduated Compression Stockings and DVT

The Cochrane group weigh in on the common thromboembolism deterrent (TED), or graduated compression  stockings (GCS).

The evidence is supportive in surgical patients, not so clear in the medical setting.

“There is high‐quality evidence that GCS are effective in reducing the risk of DVT in hospitalised patients who have undergone general and orthopaedic surgery, with or without other methods of background thromboprophylaxis, where clinically appropriate. There is moderate‐quality evidence that GCS probably reduce the risk of proximal DVT, and low‐quality evidence that GCS may reduce the risk of PE. However, there remains a paucity of evidence to assess the effectiveness of GCS in diminishing the risk of DVT in medical patients”.

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Hydroxyethyl Starch Discontinuance and CABG Outcome

This study reflects the shift away from colloids, in particular Hydroxyethyl Starch (HES), due to its association with adverse outcomes particularly in sepsis and renal dysfunction. Its use during surgery has persisted somewhat, with evidence of improved or no different outcomes using HES in abdominal surgery, not necessarily translatable to cardiac or critical care settings.

While suffering from retrospective limitations, this study showed that “for patients undergoing CABG on CPB, disinvestment in HES was associated with a reduced length of hospital stay and reduced blood product transfusion, without measurable change in death, renal failure, or dialysis rate. This association suggests that the continued use of HES in the cardiac surgical setting should be carefully reconsidered”.

Cost savings is another advantage, and many would advocate removing HES from anesthesia carts, suggested in a correspondence in the same journal (CJA)

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Crystalloids, Colloids and Renal / Disability Outcome

Colloids have been out of fashion due to evidence of increased renal injury and mortality in the critically ill. However, some studies have failed to demonstrate harm in surgical patients.

This 1 year follow up study shows that in patients undergoing major open abdominal surgery, “there was no evidence of a statistically significant difference in long-term renal function between a balanced hydroxyethyl starch and a balanced crystalloid solution used as part of intraoperative goal-directed fluid therapy, although there was only limited power to rule out a clinically significant difference. However, disability-free survival was significantly higher in the colloid than in the crystalloid group”.

The study was fairly small, and baseline WHODAS (disability) scores were not available, and the study may not be applicable to those with pre-existing renal impairment. Goal-directed pulse contour analysis was used to guide fluid administration, not universally available. Nonetheless, the eternal crystalloid-colloid debate continues!

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Perioperative management of direct oral anticoagulants (DOACS) in cardiac surgery

An international consensus on managing new oral anticoagulants in patients having cardiac surgery provides pertinent information that will enlighten their use outside cardiac surgery also.

Measurement of DOACS may be useful in emergencies or uncertainty, or in significant renal or hepatic dysfunction; however, such measurement as well as routine coagulation testing is not recommended. Greater caution is also needed in the elderly. Dabigatran is particularly dependent on renal function.

Normal prothrombin time or activated partial thromboplastin time results exclude excess levels of dabigatran, rivaroxaban and edoxaban, but not apixaban. Normal thrombin time precludes significant dabigatran plasma levels, and the aPTT shows some correlation here also – for precise measurements, the diluted thrombin time (dTT), the ecarin clotting time or the ecarin chromogenic assay may be used. For the precise measurement of drug concentrations of all FXa inhibitors, chromogenic and calibrated anti‐FXa tests are recommended.

Reversal agents: for dabigatran, idarucizumab is available; for the FXa inhibitors, andexanet alpha has been approved in the US, and ciraparantag is currently under investigation. Ultrafiltration and Hemodialysis are also discussed for Dabigatran, and non-specific approaches of varying efficacy include prothrombin complex concentrate, fibrinogen concentrate, tranexamic acid and/or factor VIIa.

In general, withholding for 2 days is appropriate. For Dabigatran, this may need 3-5 days depending on renal function. Resumption at therapeutic doses is recommended after 2-3 days and after removal of chest drains. (In the non-cardiac surgery setting, resumption may be sooner depending on bleeding risk). Prophylactic doses may be needed sooner after surgery for thromboembolic prophylaxis. Bridging agents are not recommended for interruptions less than 4 days, as increased bleeding without lower thromboembolism is reported. Individualized approaches may be needed based on CHA2DS2‐VASc Score and bleeding risk.

From an anesthesia perspective, neuraxial anesthesia performance should be equated with high bleeding risk and longer interruption may be the preferred – the ASRA provides one such set of guidelines.

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Sugammadex in the Elderly

A study using low dose Sugammadex (0.4mg/kg) showed that recovery of train-of-four ratios was slower and recurarization was more common in the elderly after Rocuronium neuromuscular blockade. Renal dysfunction and obesity imposed a higher risk; even 4mg/kg may not suffice in some. The bottom line in all elderly patients is that neuromuscular monitoring is just as imperative with Sugammadex as other agents in ensuring adequate reversal.

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Propofol vs. Inhalational Anesthesia

A systematic review and meta-analysis finds that Propofol anesthesia provides better patient satisfaction, pain scores and an especially better nausea and vomiting outcome as compared with inhalational anesthesia, with a marginal increase in time for respiratory recovery and extubation.

While some recent studies have yielded opposing results on the effect of total intravenous anesthesia on cancer recurrence and mortality, there seems ample reason to choose Propofol based anesthesia. Further prospective validating studies are suggested.

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National Emergency Laparotomy Audit (NELA)

The National Emergency Laparotomy Audit (NELA)  2016-2017 is released and provides information on how performance in England and Wales matches benchmarks, and how institutions can compare their performance.

Overall, compared with 2013:

  • hospital stays are about 15 days (4 days less)
  • 30 day mortality 9.5% (down from 11.8%)
  • 87% received a pre-operative CT Scan (up from 80%)
  • One year mortality was 77%, and three year mortality 66%
  • 75% of patients now receive an assessment of risk (up from 71% last year, and 56% in Year 1).

More negative findings were:

  • 76% of patients with sepsis did not receive antibiotics in the one-hour time frame.
  • 77% did not receive geriatric consult even though half were over 70 years old
  • 27% of patients needing the most urgent surgery did not get to the Operating Room in the recommended timeframes
  • Only 66% of consultant anesthesiologists and surgeons (attending physicians) were present in the OR after hours, and 90% during daytime.

NELA Recommendations include:

1. improving outcomes and reducing complications
2. ensuring all patients receive an assessment of their risk of death
3. delivering care within agreed timeframes for all patients
4. enabling consultant input in the perioperative period for all high risk patients
5. effective multidisciplinary working
6. supporting quality improvement.

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Acute Pain in Buprenorphine-Maintained Patients

Buprenorphine is increasingly encountered as a maintenance agent in substance use disorders rather than Methadone. Analgesia in such patients is challenging due to the complex partial agonist and antagonist properties of this agent.  Strategies include continuing buprenorphine for minor surgeries – often dividing the daily dose, or stopping it before surgery and using other opioids for analgesia in major surgery.

This study found that in those maintained on 12-16mg daily with last dose c. 17 hours ago,  up to 32mg of either IV Hydromorphine or Buprenorphine was effective. “However, the use of hydromorphone for analgesia in buprenorphine-maintained individuals confers greater abuse liability and side effects than does supplemental intravenous buprenorphine”. Analgesia requirement, side effects, drug interactions and factors like whether Buprenorphine is stopped or continued must all be taken into account.