My patient is allergic to eggs, can i use propofol? A case report and review

an interesting case report by Dr. Jamal Tashkandi

Rather than other drugs, propofol is more likely to be used for induction of anesthesia to cause an allergic reaction. Propofol is becoming the most common intravenous agent used for induction as well as maintenance of anaesthesia. Allergy to propofol is rarely reported. We present a case of 4–year-old boy presented for elective adenotonsillectomy with past medical history of eczema and multiple allergies to food. He developed what seems to be an allergic reaction to propofol. We concluded that anaesthetists should be alerted when using propofol in patients with history of atopy or several drug allergies. Current evidence suggests that egg allergic patients are not more likely to develop anaphylaxis when exposed to propofol. If reactions to drugs occurred, it is always advisable to ascertain the exact allergen in each individual case before deciding causality. Serum tryptase, skin prick, intradermal testing, or serologic testing should be done to confirm the diagnosis of an anaphylactic reaction.

source: Saudi Journal of Anesthesia

Anesthesia Awareness: Consciousness During Surgery

Dr. Orin Guidry, MUSC anesthesiologist, discusses intraoperative awareness -- the medical phenomenon commonly known as awareness under anesthesia. Dr. Guidry discusses the frequency of occurrences, gives an overview of what happens under intraoperative awareness and explains the various measures taken to decrease instances. This video is brought to you by the Medical University of South Carolina in Charleston, South Carolina.

from NEJM

Anesthesia Awareness and the Bispectral Index

Michael S. Avidan, M.B., B.Ch., Lini Zhang, M.D., Beth A. Burnside, B.A., Kevin J. Finkel, M.D., Adam C. Searleman, B.S., Jacqueline A. Selvidge, B.S., Leif Saager, M.D., Michelle S. Turner, B.S., Srikar Rao, B.A., Michael Bottros, M.D., Charles Hantler, M.D., Eric Jacobsohn, M.B., Ch.B., and Alex S. Evers, M.D.

BACKGROUND

Awareness during anesthesia is a serious complication with potential long-term psychological consequences. Use of the bispectral index (BIS), developed from a processed electroencephalogram, has been reported to decrease the incidence of anesthesia awareness when the BIS value is maintained below 60. In this trial, we sought to determine whether a BIS-based protocol is better than a protocol based on a measurement of end-tidal anesthetic gas (ETAG) for decreasing anesthesia awareness in patients at high risk for this complication.

METHODS

We randomly assigned 2000 patients to BIS-guided anesthesia (target BIS range, 40 to 60) or ETAG-guided anesthesia (target ETAG range, 0.7 to 1.3 minimum alveolar concentration [MAC]). Postoperatively, patients were assessed for anesthesia awareness at three intervals (0 to 24 hours, 24 to 72 hours, and 30 days after extubation).

RESULTS

We assessed 967 and 974 patients from the BIS and ETAG groups, respectively. Two cases of definite anesthesia awareness occurred in each group (absolute difference, 0%; 95% confidence interval [CI], −0.56 to 0.57%). The BIS value was greater than 60 in one case of definite anesthesia awareness, and the ETAG concentrations were less than 0.7 MAC in three cases. For all patients, the mean (±SD) time-averaged ETAG concentration was 0.81±0.25 MAC in the BIS group and 0.82±0.23 MAC in the ETAG group (P=0.10; 95% CI for the difference between the BIS and ETAG groups, −0.04 to 0.01 MAC).

CONCLUSIONS

We did not reproduce the results of previous studies that reported a lower incidence of anesthesia awareness with BIS monitoring, and the use of the BIS protocol was not associated with reduced administration of volatile anesthetic gases. Anesthesia awareness occurred even when BIS values and ETAG concentrations were within the target ranges. Our findings do not support routine BIS monitoring as part of standard practice. (ClinicalTrials.gov number, NCT00281489.)

N Engl J Med 2008; 358:1097-1108March 13, 2008

Anesthetic shortage worries hospitals, CBC says

"For many of the drugs that are short in the community pharmacy setting, there are other drugs available in the same classes," McKinnon said. "For drugs used for anesthesiology, the drugs are more limited." Many hospital pharmacies have been unable to get pentothal for months.

"We went from adequate stocks with no real concern that we were going to run out of them to having none of it virtually overnight," said Dr. Brian Warriner, head of anesthesiology, pharmacology and therapeutics at the University of British Columbia in Vancouver.

There are two firms currently producing propofol for the U.S., APP and Hospira, said Karen Riley, a spokeswoman for the U.S. Food and Drug Administration.

Teva Pharmaceutical announced in May 2010 that it won't make more of the sedative, because propofol is hard to manufacture and the company gets little or no profit from it, company spokeswoman Denise Bradley said at the time.

Read more: http://www.cbc.ca/health/story/2011/01/06/anesthesia-drug-shortage-hospitals-pharmacists.html#ixzz1AN0Bv7GC

General Anesthesia: A Reversible Coma, Not Sleep

December 29, 2010 — Despite what anesthesiologists may tell surgery patients, the brain under general anesthesia is not "asleep," it is placed in a reversible drug-induced coma, according to 3 neuroscientists who reviewed and synthesized the latest research in general anesthesia, sleep, and coma.

Their review, 3 years in the making, appears in the December 30 issue of The New England Journal of Medicine.

"Anesthesiologists use the term 'sleep' so as not to scare patients with the word 'coma,' " Emery N. Brown, MD, PhD, from the Department of Anesthesia, Critical Care, and Pain Medicine at Massachusetts General Hospital and Harvard Medical School, Boston, pointed out in correspondence with Medscape Medical News. In reality, however, general anesthesia is a type of coma.

Dr. Brown's coauthors on the review are Ralph Lydic, PhD, from the University of Michigan, Ann Arbor, whose expertise is sleep medicine, and Nicholas D. Schiff, MD, from Weill Cornell Medical College in New York City, who specializes in recovery from coma.

"This review was prompted by a recognition that common brain circuit mechanisms may underlie aspects of general anesthesia and recovery from coma and that thinking through the links across these phenomena and their distinction from the natural processes of sleep would reveal important insights," Dr. Schiff told Medscape Medical News.

The realization that general anesthesia and coma have more in common with each other than differences "is very exciting," Dr. Schiff said, "because it gives us new ways to understand each of these states.

"Measuring brain circuit mechanisms may lead to greater diagnostic accuracy and targeted therapeutic strategies for predicting and supporting the recovery process from coma after severe brain injuries," he added. Monitoring brain function under general anesthesia may also help in developing new sleep aids.

Nothing Mysterious About the Anesthetized Brain

The scientists note in their article that there is substantial overlap between the electroencephalograms of patients in coma and of patients during general anesthesia. "The [electroencephalogram] of the states of coma recovery can resemble those of the awake, general anesthesia, or sleep state, depending on how extensive the brain injury is and where the patient is in terms of recovery," Dr. Brown noted.

The team also notes that anesthetic drugs induce unconsciousness or alter arousal through actions at multiple sites in the cerebral cortex, brainstem, and thalamus.

Contrary to what is commonly stated, how these drugs create the state of general anesthesia "is not mysterious," Dr. Brown explained, and "there are multiple mechanisms even for a single drug."

General anesthesia, the scientists say, is functionally equivalent to brainstem death, and perhaps explains why some patients do not fully recover consciousness for several hours after general anesthesia, as well as why postoperative cognitive dysfunction could persist in elderly patients for several months afterward.

"One thing which is evident regarding recovery from general anesthesia is that it tracks the return of function in the brainstem from bottom (respiration) to top (eye-movements and arousal centers)," Dr. Brown noted.

Dr. Brown, Dr. Lydic, and Dr. Schiff hope their article will facilitate more informed discussions among anesthesiology, sleep, and coma researchers and lead to new approaches to creating the state of general anesthesia, sedation, and sleep, as well as new approaches to facilitating coma recovery.

They hope it will also lead to better education of the public about general anesthesia.

This research was supported by the National Institutes of Health, the James S. McDonnell Foundation, Massachusetts General Hospital Department of Anesthesia, Critical Care and Pain Medicine, and University of Michigan Department of Anesthesiology.

N Engl J Med. 2010;363:2638-2650.

General Anesthesia: A Reversible Coma, Not Sleep

Malignant Hyperthermia: Are we becoming less suspicious?

Guidelines from the European Malignant Hyperthermia Group
K. P. E. Glahn; F. R. Ellis; P. J. Halsall; C. R. Müller; M. M. J. Snoeck; A. Urwyler; F. Wappler

Key points

• MH is rare, but its incidence may be increasing.
• Prompt recognition is the key to a safe outcome.
• These guidelines provide a template for diagnosis and treatment.
• Suspected cases and their relatives should be followed up and investigated for MH.

The first known case of malignant hyperthermia (MH) survived because the anaesthetist quickly stopped anaesthesia and surgery when he observed a set of strange clinical signs. However, he was already alerted to a potential problem because of a preoperative history of several anaesthesia-related deaths in the patient's family. The key lesson learnt from this event is as relevant today as it was back in 1960: survival from an MH crisis is highly dependent on early recognition and prompt action.

MH crises are very rare and an increasing use of total i.v. anaesthesia (TIVA) using non-triggering agents in many Western European countries is likely to make it even rarer, leading to the potential risk of reduced awareness of MH among anaesthetists and theatre staff. However, recent reports showed that the frequency of MH episodes has increased, and due to the autosomal-dominant inheritance in humans, prevalence of MH can be estimated up to 1:3000. In addition, dantrolene, the cornerstone of successful MH treatment, is unavailable in many institutions in Eastern European countries and in large areas around the world due to its cost, thereby increasing the risk of MH fatalities in these areas.

The European Malignant Hyperthermia Group (EMHG), a leading international society working on MH, has therefore decided to publish guidelines for the detection and handling of an MH crisis. Many institutions have drawn up local guidelines and most countries with an MH Investigation Unit have developed national guidelines. The EMHG Executive committee collected and reviewed all guidelines available from the various MH centres in order to provide a consensus document. It is hoped that this will be helpful, especially for countries having no MH centre and therefore no national guidelines.

While recognizing that it is impossible to stipulate the exact set-up for dealing with MH for each institution worldwide, we are, nevertheless, convinced that the EMHG guidelines will provide a sound basis to help anaesthetists and theatre staff in Europe and around the world ensure that best practice is followed and enable them to plan ahead.

The guidelines consist of two textboxes: Box 1 on recognizing MH and Box 2 on the treatment of an MH crisis.

Box 1 EMHG Guidelines: Recognizing an MH crisis

Early recognition of an impending MH crisis and its immediate treatment is essential for the patient's survival. As the clinical signs associated with MH are not unique, anaesthetists must be able to recognize a pattern of signs in order to make a rapid diagnosis.

Any patient may develop MH during or shortly after an anaesthetic where trigger agents are used—this can occur even in patients who have had uneventful general anaesthesia previously.

Trigger agents are

• all volatile (inhalation) anaesthetic agents;
• succinylcholine.

Clinical signs

Early signs

• Metabolic
  
  • Inappropriately elevated CO₂ production (raised end-tidal CO₂ on capnography, tachypnoea if breathing spontaneously).
  • Increased O₂ consumption.
  • Mixed metabolic and respiratory acidosis.
  • Profuse sweating.
  • Mottling of skin.
• Cardiovascular
  
  • Inappropriate tachycardia.
  • Cardiac arrhythmias (especially ectopic ventricular beats and ventricular bigemini).
  • Unstable arterial pressure.
• Muscle
  
  • Masseter spasm if succinylcholine has been used.
  • Generalized muscle rigidity.

Later signs

• Hyperkalaemia.
• Rapid increase in core body temperature.
• Grossly elevated blood creatine phosphokinase levels.
• Grossly elevated blood myoglobin levels.
• Dark-coloured urine due to myoglobinuria.
• Severe cardiac arrhythmias and cardiac arrest.
• Disseminated intravascular coagulation.

Differential diagnosis

• Insufficient anaesthesia, analgesia, or both.
• Infection or septicaemia.
• Insufficient ventilation or fresh gas flow.
• Anaesthetic machine malfunction.
• Anaphylactic reaction.
• Phaeochromocytoma.
• Thyroid crisis.
• Cerebral ischaemia.
• Neuromuscular disorders.
• Elevated end-tidal CO₂ due to laparoscopic surgery.
• Ecstasy or other dangerous recreational drugs.
• Malignant neuroleptic syndrome.

Box 2 EMHG Guidelines: Managing an MH Crisis

Start treatment as soon as an MH crisis is suspected.

The clinical presentation of MH varies and treatment should be modified accordingly.

Treatment

• Immediately
  
  • Stop all trigger agents.
  • Hyperventilate (use a minute volume 2–3 times normal) with 100% O₂ at high flow.
  • Declare an emergency and call for help.
  • Change to non-trigger anaesthesia (TIVA).
  • Inform the surgeon and ask for termination/postponement of surgery.
  • Disconnect the vaporizer—do not waste time changing the circuit/anaesthetic machine.
• Dantrolene
  
  • Give dantrolene 2 mg kg⁻¹ i.v. (ampoules of 20 mg are mixed with 60 ml sterile water).
  • Obtain dantrolene from other sources, for example, pharmacy/nearby hospitals—at least 36–50 ampoules may be needed for an adult patient.
  • Dantrolene infusions should be repeated until the cardiac and respiratory systems stabilize.
  • The maximum dose (10 mg kg⁻¹) may need to be exceeded.
• Monitoring
  
  • Continue routine anaesthetic monitoring (Sa_o2, ECG, NIAP, e′_co2).
  • Measure core temperature.
  • Establish good i.v. lines with wide-bore cannulas.
  • Consider inserting an arterial and central venous line, and a urinary catheter.
  • Obtain samples for measurement of K⁺, CK, arterial blood gases, myoglobin, and glucose.
  • Check renal and hepatic function and coagulation.
  • Check for signs of compartment syndrome.
  • Monitor the patient for a minimum of 24 h (ICU, HDU, or in a recovery unit).

Symptomatic treatment

• Treat hyperthermia
  
  • 2000–3000 ml of chilled (4°C) 0.9% saline at i.v.
  • Surface cooling: wet, cold sheets, fans, and ice packs placed in the axillae and groin.
  • Other cooling devices if available.
  • Stop cooling once temperature <38.5°C
• Treat hyperkalaemia
  
  • Dextrose: 50%, 50 ml with 50 IU insulin (adult dose).
  • CaCl₂: 0.1 mmol kg⁻¹ i.v. (e.g. 7 mmol=10 ml for a 70 kg adult).
  • Dialysis may be required.
• Treat acidosis
  
  • Hyperventilate to normocapnoea.
  • Give sodium bicarbonate i.v. if pH < 7.2.
• Treat arrhythmias
  
  • Amiodarone: 300 mg for an adult (3 mg kg⁻¹ i.v.).
  • β-blockers (e.g. propranolol/metoprolol/esmolol)—if tachycardia persists.
• Maintain urinary output >2 ml kg⁻¹ h⁻¹
  
  • Furosemide 0.5–1 mg kg⁻¹.
  • Mannitol 1 g kg⁻¹.
  • Fluids: crystalloids (e.g. lactated Ringer's solution or 0.9% saline) i.v.

Consult your local Malignant Hyperthermia Investigation Unit about the case

Patients suspected of being MH-susceptible should undergo diagnostic testing using in vitro contracture testing (IVCT) at a designated MH-laboratory (www.emhg.org).

Action cards adapted for local conditions and resources can be extremely helpful in dealing with an MH crisis. Such a system, designed by the Australian and New Zealand MH group (MHANZ), has proved to be a success in full-scale simulation and can save valuable time.

It is important that once a case of MH is suspected, either because of a full-blown MH crisis or a set of symptoms suggestive of MH which resolved on stopping any trigger agents, the patient and their relatives should always be referred to a regional or national MH centre for further investigation wherever possible. The EMHG has previously published guidelines for diagnosing MH susceptibility using the IVCT test and genetic testing when indicated.

source: Br J Anaesth. 2010;105(4):417-420.

Lipid Reversal of Bupivacaine Cardiac Arrest: A Step Forward in Patient Safety?

The question remains, then, what will now be your response when a patient shows signs and symptoms of local anesthetic toxicity with, or even before, failing CPR? Does the growing number of case reports documenting successful resuscitation via the use of lipid emulsion therapy intrigue you enough to have the drug readily available where blocks are performed in your practice? Will you abide the wise counsel from de Jong that lipid therapy is not a panacea for all forms of toxicity?Will you proceed with the surgical case after your patient has recovered from a local anesthetic overdose by treatment with lipid emulsion? The weight of the evidence, based upon case report quality data, is not overwhelming, but must we wait for more detailed research to specify all of the clinical innuendos for using this treatment?

Although the hazards of the doses of lipid given in this therapy are not known, for a patient in the desperate circumstance of local anesthetic toxicity and failing or failed resuscitation, lipid emulsion therapy seems to be a worthy and effective consideration. It would be naive to substitute this treatment for standard CPR, but it is not premature to apply it once it is clear that the likely explanation for a patient’s cardiovascular collapse is local anesthetic toxicity and when conventional resuscitation efforts are not generating success. This conclusion is not based on a flash-in-a-pan experiment but rather, on a methodical, scientific evolution of a concept tested in more than one animal model, and now showing dramatic results in a few humans. 

see the full-text HERE

Oncologic Surgery: Anesthetic Techniques and Implications

Should we re-evaluate our classical techniques for oncologic surgery?

Effect of anaesthetic technique and other perioperative factors on cancer recurrence

1. G. L. Snyder (1,2,*) and
2. S. Greenberg (1,2)

1. ¹Department of Anesthesia and Perioperative Medicine and
2. ²Department of Oncology and Hematology, University of California San Francisco, 505 Parnassus Ave., San Francisco, CA 94143, USA

Surgical excision is the mainstay of treatment for potentially curable solid tumours. Metastatic disease is the most important cause of cancer-related death in these patients. The likelihood of tumour metastases depends on the balance between the metastatic potential of the tumour and the anti-metastatic host defences, of which cell-mediated immunity, and natural killer cell function in particular, is a critical component. It is increasingly recognized that anaesthetic technique and other perioperative factors have the potential to effect long-term outcome after cancer surgery. 

Surgery can inhibit important host defences and promote the development of metastases. Anaesthetic technique and drug choice can interact with the cellular immune system and effect long-term outcome. The potential effect of i.v. anaesthetics, volatile agents, local anaesthetic drugs, opiates, and non-steroidal anti-inflammatory drugs are reviewed here. 

There is particular interest at present in the effect of regional anaesthesia, which appears to be beneficial. Retrospective analyses have shown an outcome benefit for paravertebral analgesia for breast cancer surgery and epidural analgesia for prostatectomy. Blood transfusion, pain, stress, and hypothermia are other potentially important perioperative factors to consider. 

Key points

• Metastatic disease is the most important cause of cancer-related death in patients after cancer surgery.
• Drugs and techniques used perioperatively may influence outcome.
• In vitro and animal study evidence suggests potential mechanisms altered by anaesthetic drugs.
• Human studies are limited but regional anaesthesia may be beneficial.
• There is a need for large-scale prospective studies.

full-text HERE

Sugammadex - finally something new to the anesthesiologist's toolbox

Sugammadex is a modified gamma-cyclodextrin molecule, which is in essence a ring of sugar molecules that form a doughnut shape with a hole in the middle. 

Its ability to reverse the effects of NMBAs was discovered during a 'eureka' moment when a team of Scottish-based Schering-Plough researchers were investigating how to dissolve rocuronium in the laboratory. It was discovered that gamma-cyclodextrin has a structure that allows it to encapsulate rocuronium and vecuronium by trapping these NMBA molecules in the hole at the centre of the molecule, forming a new, inactive complex which can then be excreted from the body. 

Following the discovery, the Schering-Plough team refined the cyclodextrin structure to make it as effective as possible and created the sugammadex molecule. The research was awarded the prestigious Royal Society of Chemistry's Malcolm Campbell Memorial prize in June 2007.

The Very Basics of General Anesthesia

General anesthesia is used to block pain, put the body to sleep, and regulate bodily functions during surgery. This 3D medial animation demonstrates the different ways general anesthesia can be administered prior to a surgical operation.

RSI - Rapid Sequence Induction

Often advocated for patients at risk for aspiration, ex. obstetrical patients, those with intraabdominal processes, etc., several considerations must be taken into account: first, what is the risk of aspiration? Second, how effective are techniques designed to reduce aspiration risk? Third, do these techniques require a tradeoff in terms of airway safety? Fourth, how do different airway equipment affect the risk of aspiration? 

Propofol, please rescue me! Unusual application on Cardiac Anesthesia

Aside from low blood pressure (mainly through vasodilation) and transient apnea following induction doses, one of propofol's most frequent side effects is pain on injection, especially in smaller veins. This pain can be mitigated by pretreatment with lidocaine. Patients show great variability in their response to propofol, at times showing profound sedation with small doses. A more serious but rare side effect is dystonia. Mild myoclonic movements are common, as with other intravenous hypnotic agents. Propofol appears to be safe for use in porphyria, and has not been known to trigger malignant hyperpyrexia.