Category Archives: Complications during anesthesia

AEQ1: Revised Cardiac Risk Index (RCRI) and ACS-NSQIP

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  • Anaesthesia Exam Question:1
  • Revised Cardiac Risk Index (RCRI) is one of the commonly used perioperative risk indices
  • The RCRI determines preoperative risk based on risk of surgery, history of ischemic heart disease, congestive heart failure, cerebrovascular disease, preoperative use of insulin and creatinine greater than 2.0 mg/ dL. 
  • The total score ranges from 0 to 6, with higher scores indicating a higher risk of major adverse cardiac events (MACE). The risk categories and their corresponding scores are as follows:
  • 0 points: Low risk (MACE rate <1%)
  • 1-2 points: Intermediate risk (MACE rate 1-5%)
  • 3-6 points: High risk (MACE rate >5%)
  • RCRI is less accurate in patients undergoing vascular, noncardiac surgery. In addition, as RCRI does not capture risk factors for noncardiac causes of perioperative mortality, it does not predict all-cause mortality well
  • American College of Surgeons’ National Surgical Quality Improvement Program (ACS-NSQIP) is a universal surgical risk calculator model developed using a web-based tool . The ACS-NSQIP calculator incorporates 20 patient risk factors in addition to the surgical procedure. From this input, it calculates the percentage risk of a MACE, death, and 8 other outcomes. This risk calculator may offer the best estimation of surgery-specific risk of a MACE and death. It has excellent performance for predicting mortality and morbidity. It has not been validated in an external population outside the NSQIP. This classification has poor inter-rater reliability
  • Surgery-specific risk calculation using ACS-NSQIP report the rate of cardiac death or non-fatal MI and are noted to be greater than 5% in high-risk procedures, 1% to 5% in intermediate-risk procedures, and less than 1% in low-risk procedures. Emergency surgery is associated with higher risk of MACEs compared with elective procedures. 

Complications of Laparoscopy

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  • The commonest structure that can be injured by the laparoscope is the distended stomach. So pass a nasogastric tube and aspirate the stomach contents especially if the induction has involved prolonged bag and mask ventilation.
  • Regurgitation of gastric contents can happen
  • Pulmonary oedema from fluid infusions and the head-down position
  • Insufflation is the most hazardous phase; A demonstrable gas embolism can occur in 1 out of 2000 patients; so watch for high insufflating pressures and low flow. Signs of gas embolism include arrhythmia, hypotension, cyanosis and cardiac arrest. The safest technique is to use CO2 for the pneumoperitoneum rather than N2O, because CO2 is more soluble and if an embolism occurs, it will resolve faster. Watch the indicators on the insufflating machine continuously during inflation. Pressure over 3 kPa or total volume insufflated exceeding 5 litres are hazardous. Caval compression and reduced venous return, with lowered cardiac output, may be a consequence of intra-abdominal pressure exceeding 4 kPa.
  • The pressure effect of the insufflating gas will also splint the diaphragm and impede the mechanism of breathing.
  • Avoid excessive head down tilt, and always be prepared for laparotomy.
  • The end-tidal CO2 will rise during the course of a prolonged procedure and minute volume should be adjusted to compensate.
  • Pneumothorax and surgical emphysema have been described, associated with prolonged surgery.
  • Shoulder-tip pain, from diaphragmatic irritation, is a common postoperative problem.

Cricoarytenoid arthritis: an ominous entity for the anesthesiologist

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  • Rheumatoid arthritis is the most common cause of this condition
  • Can also may be associated with bacterial infections, mumps, diphtheria, tuberculosis and ankylosing spondylitis,systemic lupus erythematosus, gout, progressive systemic sclerosis
  • The cricoarytenoid joint has a synovial lining and bursa. Its mobility is vital for speech, respiration, and protection from aspiration.
  • Effusion, pannus formation, joint erosion, and ankylosis may compromise the joint’s functions.
  • Its involvement may be unsuspected or mistaken for asthma until intubation or after extubation and may necessitate a surgical airway.
  • Dysphonia, dyspnea, or stridor should raise suspicion of this possibility.
  • Complete airway obstruction is a well described but an uncommon complication
  • Laryngoscopy may reveal a rough and thick mucosa with narrowing of the vocal chink.
  • Airway obstruction occurs most commonly in patients with long-standing rheumatoid arthritis with polyarticular and systemic involvement
  • But laryngeal stridor has been described as the sole manifestation of this disease too!
  • Always anticipate this as a cause for postoperative stridor in such patients.

POSTOPERATIVE VISUAL LOSS

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Corneal abrasion is the most common ocular complication after general anesthesia

Ischemic Optic neuropathy (ION) and Central Retinal Artery Occlusion (CRAO) are the commonest causes for postoperative visual loss

ISCHEMIC OPTIC NEUROPATHY (ION)

More common among the two

Most often seen after prolonged surgery in prone position

Venous congestion–> Raised Intra Ocular Pressure (IOP) due to Raised Intra Orbital Pressure –> Intra Orbital ‘Compartment Syndrome’

Hypotension, Diabetes, Vascular disease, Smoking etc also may be important in the etiopathogenesis

Treatment:

Reduce optic nerve edema as it passes through posterior scleral foramen with steroids and mannitol

Optimal oxygen delivery by ensuring normal blood pressure and hematocrit

Clear all obstruction to venous drainage

Chance of visual recovery is less

CENTRAL RETINAL ARTERY OCCLUSION (CRAO)

External pressure on eye and embolism are risk factors

An echocardiogram and carotid ultrasound may help us to find an embolic source

Reference: White E, David DB. Care of the eye during anaesthesia and intensive care. Anaesth Intens Care Med. 2007; 8(9): 383–386.

Anaphylactic Reactions on Muscle Relaxants

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Neuromuscular blocking agents (NMBAs) represent the most frequently incriminated substances for allergic reactions among all drugs used in the perioperative period, ranging from 50 to 70% (1)

They are substances responsible for IgE-mediated anaphylaxis. Among NMBAs, the following substances have been incriminated, in decreasing order of importance: suxamethonium, vecuronium, atracurium, pancuronium, rocuronium, mivacurium and cisatracurium.(1)

Incidence of anaphylactic reactions are seen more with suxamethonium and rocuronium. (2) (3)

These reactions are more severe than with latex allergy

Seem to occur more frequently in women than in men.

If rapid-sequence induction is not mandatory, safer alternatives like cisatracurium can be used , in place of Rocuronium

Regarding suxamethonium, more frequently it causes histamine release from mast cells and basophils, resulting in flushing and urticaria (without anaphylactic reactions)(4)

Regarding atracurium , histamine release is observed in 40% of patients who receive doses over 0.5 mg/kg, resulting in transient hypotension and tachycardia; this can be prevented by injecting the drug slowly over 75 seconds, reducing the dose or prior treatment with 0.1 mg/kg chlorpheniramine and 2 mg/kg cimetidine i.v. (4)

Cisatracurium will not cause histamine release in clinical dose range. Cisatracurium had the lowest rate of cross-reactivity in patients who had previously suffered anaphylaxis to rocuronium or vecuronium.(4)

Mivacurium causes transient fall in b.p. due to histamine release with doses above 0.2 mg/kg(4)

The estimated sensitivity of skin tests for muscle relaxants is approximately 94 to 97 %. (1)

#anaphylaxis , #allergy , #anaesthesia , #MuscleRelaxants , #criticalcare , #nmba , #AnaesthesiaComplications , #pharmacology ,#rocuronium , #cisatracurium

Reference:

(1) www.worldallergy.org , Allergy to Anesthetic Agents, Mertes Paul Michel, Demoly Pascal, Stenger Rodolphe , Updated May 2013 ,Originally posted: October 2007, Reviewed by: Mario Sánchez-Borges
(2)A. Gullo(Editor) Anaesthesia, Pain, Intensive Care and Emergency – A.P.I.C.E.
(3) Proceedings of the 22 nd Postgraduate Course in Critical Care Medicine, Incidents Provoked Specifically by Certain Drugs Used in Anaesthesia M. K LIMEK , T.H. O TTENS ,F.G RÜNE
(4) Lee’s Synopsis of Anaesthesia,13/e, p:191-193
(5) Br J Anaesth. 2013 Jun;110(6):981-7. Anaphylaxis to neuromuscular blocking drugs: incidence and cross-reactivity in Western Australia from 2002 to 2011., Sadleir PH1, Clarke RC, Bunning DL, Platt PR.