TXA in burn

Q: What is the 20:40 rule for the use of Tranexamic acid (TXA) in burn patients who require surgical excisions?

Answer: 

Evidence supports the use of TXA for patients who require burn wound excisions. It potentially reduces blood loss and transfusion requirements.

• Patients who require over 20% TBSA of burn wound excisions are usually given a gram bolus of TXA
• Patients who require over 40% TBSA of burn wound excisions are usually given a gram bolus of TXA, followed by a 1-gram drip over eight hours

Topical TXA, with or without epinephrine, can also be used during surgery, depending on the surgeon's preference.

*Total Body Surface Area

#burn

#surgical-critical-care

References:

1. Tapking C, Hundeshagen G, Kirchner M, Fischer S, Kneser U, Bliesener B. Tranexamic acid reduced blood transfusions in acute burn surgery: A retrospective case-controlled trial. Burns. 2022 May;48(3):522-528. doi: 10.1016/j.burns.2022.03.002. Epub 2022 Mar 16. PMID: 35339324.

2. Fijany AJ, Givechian KB, Zago I, et al. Tranexamic acid in burn surgery: A systematic review and meta-analysis. Burns 2023; 49:1249.

3. Hesamirostami M, Ramezanpour E, Asadpour-Sorkhkolaee H, Jamali A, Amini M, Moghaddam MR. The effect of tranexamic acid on blood loss after surgical excision in burn patients. Burns. 2025 Dec;51(9):107682. doi: 10.1016/j.burns.2025.107682. Epub 2025 Aug 25. PMID: 41109167.

Oral valganciclovir and ganciclovir

Q: Valganciclovir gets converted to ganciclovir in? - select one

A) Intestinal wall

B) Kidney

C) Vessel (endothelium)

D) Stomach (Gastric acid)

Answer: A

Valganciclovir is an L-valyl ester of ganciclovir. It is taken orally, represents a major advance in the treatment of cytomegalovirus (CMV) infection, and is widely favored over ganciclovir. It's absolute bioavailability as ganciclovir from valganciclovir tablets, when taken with food, is about 60 percent.

After oral administration, it is rapidly hydrolyzed to ganciclovir in the intestinal wall and liver.

#pharmacology

#ID

References:

1. Cvetković RS, Wellington K. Valganciclovir: a review of its use in the management of CMV infection and disease in immunocompromised patients. Drugs 2005; 65:859.

2. Curran M, Noble S. Valganciclovir. Drugs. 2001;61(8):1145-50 ; discussion 1151-2. doi: 10.2165/00003495-200161080-00013. PMID: 11465875.

3. Suganuma E, Sakata H, Adachi N, Asanuma S, Furuichi M, Uejima Y, Sato S, Abe T, Matsumoto D, Takahashi R, Yamamoto S, Kawano Y, Arai T, Oh-Ishi T. Efficacy, safety, and pharmacokinetics of oral valganciclovir in patients with congenital cytomegalovirus infection. J Infect Chemother. 2021 Feb;27(2):185-191. doi: 10.1016/j.jiac.2020.08.019. Epub 2020 Sep 6. PMID: 32907793.

Hydrocortisone and Mineralocorticoid activity

Q: What is the ratio of Mineralocorticoid: Glucocorticoid activity in hydrocortisone? - select one

A) 1:1

B) 1:2

C) 1:3

D) 1:4

Answer: A

Hydrocortisone continues to be the favored drug in ICUs for stress dose steroids in sepsis and other clinical situations where adrenal insufficiency is suspected. This is due to a 1:1 ratio of mineralocorticoid: glucocorticoid activity.

Dexamethasone has the least, rather negligible, mineralocorticoid activity.

#pharmacology

#endocrinology

References:

1. Ekman B, Quinkler M, Zhang P, Isidori AM, Murray RD, Wahlberg J; EU-AIR investigators. Mineralocorticoid effects of fludrocortisone and hydrocortisone in primary adrenal insufficiency: EU-AIR patient data. J Endocrinol Invest. 2025 Oct;48(10):2381-2392. doi: 10.1007/s40618-025-02657-7. Epub 2025 Sep 6. PMID: 40913682; PMCID: PMC12518465.

2. Venkatesh B, Cohen J. Hydrocortisone in Vasodilatory Shock. Crit Care Clin. 2019 Apr;35(2):263-275. doi: 10.1016/j.ccc.2018.11.005. Epub 2019 Jan 28. PMID: 30784608.

3. Sattar NA, Gaw A. Mineralocorticoid effects of high dose hydrocortisone. BMJ. 1995 Jul 22;311(6999):260. doi: 10.1136/bmj.311.6999.260b. PMID: 7627063; PMCID: PMC2550311.

Basophilic stippling

Q: Basophilic stippling can be seen in all of the following EXCEPT? - select one

A) Hb C / Hb SC disease

B) Thalassemia

C) Alcohol abuse

D) Lead poisoning

E) Hereditary pyrimidine 5'-nucleotidase deficiency

Answer: A

The objective of this question is to continue to emphasize the basic teachings learned in early medical school to apply at the bedside later as a clinician! The slide-preparation training in early lab classes in med school remains highly relevant in practice later on.

Basophilic stippling refers to blue granules of various sizes dispersed throughout the RBC cytoplasm. They are actually precipitated ribosomes. They can be seen in thalassemia, excess alcohol use, lead and heavy metal poisoning, and in hereditary pyrimidine 5'-nucleotidase deficiency.

Hb C disease or Hb SC disease usually has hemoglobin crystals, especially if the blood sample has become dehydrated before the peripheral smear is made. The crystals are usually hexagonal or rhomboid in shape.

#hematology

#pathology

References:

1. Munoz J, Guo Y. Basophilic stippling: a lead to the diagnosis. Blood. 2011 Nov 17;118(20):5370. doi: 10.1182/blood-2010-12-320911. Erratum in: Blood. 2014 Jan 9;123(2):302. PMID: 22204026.

2. Cheson BD, Rom WN, Webber RC. Basophilic stippling of red blood cells: a nonspecific finding of multiple etiology. Am J Ind Med. 1984;5(4):327-34. doi: 10.1002/ajim.4700050409. PMID: 6202140.

Antidepressant Discontinuation Syndrome

Q: Which of the following is usually not present in the antidepressant discontinuation syndrome? - select one

A) Chills without fever

B) Rhinorrhea

C) Electric shock-like sensations

D) Vivid dreams

E) Pupillary dilation

Answer: E

The antidepressant discontinuation syndrome may cause new-onset somatic and neuropsychiatric symptoms. Importantly, discontinuation symptoms differ from any adverse effects that occurred during active treatment with the antidepressant. These symptoms include:

• Dizziness
• Headache
• Insomnia
• Irritability
• Nausea/vomiting
• Agitation
• Anxiety
• Chills without fever (choice A)
• Diaphoresis
• Dysphoria
• Fatigue
• Lethargy
• Myalgias
• Rhinorrhea (choice B)
• Paresthesias
• Electric shock-like sensations (choice C)
• Tremor
• Vivid dreams (choice D)
• Anorexia 
• Loss of balance 
• Cognitive impairment
• Crying spells
• Dry mouth 
• Hypertension 
• Hypomania and mania
• Psychosis (with auditory and/or visual hallucinations
• Sexual dysfunction 
• Suicidal ideation
• Tinnitus 

Pupillary dilation occurs in opioid withdrawal but not in antidepressant discontinuation syndrome.

#psychiatry

#pharmacology

References:

1. Fornaro M, Cattaneo CI, De Berardis D, Ressico FV, Martinotti G, Vieta E. Antidepressant discontinuation syndrome: A state-of-the-art clinical review. Eur Neuropsychopharmacol. 2023 Jan;66:1-10. doi: 10.1016/j.euroneuro.2022.10.005. Epub 2022 Nov 4. PMID: 36345093.

2. Gabriel M, Sharma V. Antidepressant discontinuation syndrome. CMAJ. 2017 May 29;189(21):E747. doi: 10.1503/cmaj.160991. PMID: 28554948; PMCID: PMC5449237.

3. Kalfas M, Tsapekos D, Butler M, McCutcheon RA, Pillinger T, Strawbridge R, Bhat BB, Haddad PM, Cowen PJ, Howes OD, Joyce DW, Nutt DJ, Baldwin DS, Pariante CM, Lewis G, Young AH, Lewis G, Hayes JF, Jauhar S. Incidence and Nature of Antidepressant Discontinuation Symptoms: A Systematic Review and Meta-Analysis. JAMA Psychiatry. 2025 Sep 1;82(9):896-904. doi: 10.1001/jamapsychiatry.2025.1362. Erratum in: JAMA Psychiatry. 2025 Nov 1;82(11):1153. doi: 10.1001/jamapsychiatry.2025.2398. PMID: 40632531; PMCID: PMC12242823.

VQI prohibitive risk

Q: What is a prohibitive risk in vascular surgery?

Answer: Patients with high mortality where less invasive intervention is preferred 

There are a few risk calculators to estimate the risk of perioperative vascular morbidity and mortality. The updated guidelines from the Society for Vascular Surgery (SVS) endorse the use of a scoring system based on data from the Vascular Study Group of New England, part of the National Vascular Quality Initiative (VQI). 

Per the VQI risk calculator, there are four risk categories: low, moderate, high, and prohibitive.

There have been further sub-group categories, such as 

• Respiratory Risk Groups (RAE): Low, Intermediate-Low, Intermediate-High, and High.
• Cardiac Risk Index (VQI CRI): Predicts myocardial infarction based on pre-operative patient characteristics and procedure type (CEA, EVAR, INFRA, SUPRA, OAAA).
• Frailty Assessment (VQI-FS): Uses seven variables (CHF, renal impairment, COPD, non-home dwelling, non-ambulatory, anemia, underweight) to predict 9-month mortality.
• Adverse Outcomes Categories (General): Used in research, these include 1-year follow-up, 30-day mortality, composite perioperative adverse events, and 12-month mortality.

Calculators are available at: https://www.vqi.org/

#surgical-critical-care

References:

1. Chaikof EL, Dalman RL, Eskandari MK, et al. The Society for Vascular Surgery practice guidelines on the care of patients with an abdominal aortic aneurysm. J Vasc Surg 2018; 67:2.

2. Cronenwett JL, Kraiss LW, Cambria RP. The Society for Vascular Surgery Vascular Quality Initiative. J Vasc Surg. 2012 May;55(5):1529-37. doi: 10.1016/j.jvs.2012.03.016. PMID: 22542349.

3. Bertges DJ, Neal D, Schanzer A, Scali ST, Goodney PP, Eldrup-Jorgensen J, Cronenwett JL; Vascular Quality Initiative. The Vascular Quality Initiative Cardiac Risk Index for prediction of myocardial infarction after vascular surgery. J Vasc Surg. 2016 Nov;64(5):1411-1421.e4. doi: 10.1016/j.jvs.2016.04.045. Epub 2016 Jul 19. PMID: 27449347; PMCID: PMC5079798.

HILI and Causality Assessment Tools

Q: In case of suspected herb-induced liver injury (HILI), different causality assessment models may help in differential diagnosis of such products.

A) True

B) False

Answer: B

Different causality assessment models have been developed for the assessment of Drug-Induced Liver Injury (DILI), which include:

• Roussel Uclaf Causality Assessment Method (RUCAM)
• Drug-Induced Liver Injury Network (DILIN) Causality Scoring System 
• Maria and Victorino scale 
• Naranjo scale

Unfortunately, none provides a good assessment of HILI due to product variability and contamination.

HILI due to herbal and dietary supplements (HDS) requires the following elements to be satisfied:

• Exposure must precede the onset of liver injury* 
• Underlying liver disease should be excluded^
• Injury may improve when the HDS is stopped 

* Although the latent period is highly variable

^ In some cases, injury may initially worsen for days or weeks, and in cases of acute liver failure, declining liver biochemical tests may indicate deterioration rather than improvement

#hepatology

References:

Hayashi PH. Causality assessment in drug-induced liver injury. Semin Liver Dis 2009; 29:348.

Chalasani NP, Maddur H, Russo MW, et al. ACG Clinical Guideline: Diagnosis and Management of Idiosyncratic Drug-Induced Liver Injury. Am J Gastroenterol 2021; 116:878.

Hayashi PH, Lucena MI, Fontana RJ. RECAM: A New and Improved, Computerized Causality Assessment Tool for DILI Diagnosis. Am J Gastroenterol 2022; 117:1387.

St John's Wort and Clopidogrel

Q: 54 years old Asian male, recently discharged from the hospital after cardiac intervention due to an acute myocardial infarction, and on Dual Antiplatelet Therapy (DAPT), presented with severe upper GI bleed. Patient reports depressive mental health issue after his 'heart attack', and starts taking herbal medicines to feel better. Which widely used non-prescription drug should be suspected?

Answer: St. John's wort

The botanical name of St. John's Wort is Hypericum Perforatum. It is one of the most widely used herbal antidepressants worldwide. In the United States, an estimated 4.4 million adults are using it. It is particularly very popular in Eastern and Asian cultures. Frequently, its use goes unreported. 

St. John's wort increases the activity of clopidogrel by inducing CYP P450 enzymes, and can put patients at higher risk of bleeding. The objective of this question is to highlight patients' education on the risk of over-the-counter (OTC) and non-prescription herbal products when they are on life-saving drugs.

But here is the curveball: Some physicians use it in patients who are non-responders to clopidogrel to enhance its activity! The authors of this question would advise against such an adventure.

#pharmacology

#cardiology

References:

1. Monteiro MD, Dias ACP, Costa D, Almeida-Dias A, Criado MB. Hypericum perforatum and Its Potential Antiplatelet Effect. Healthcare (Basel). 2022 Sep 15;10(9):1774. doi: 10.3390/healthcare10091774. PMID: 36141386; PMCID: PMC9498564.

2. Trana C, Toth G, Wijns W, Barbato E. St. John's Wort in patients non-responders to clopidogrel undergoing percutaneous coronary intervention: a single-center randomized open-label trial (St. John's Trial). J Cardiovasc Transl Res. 2013 Jun;6(3):411-4. doi: 10.1007/s12265-013-9455-2. Epub 2013 Mar 6. PMID: 23463297.

3. Lau WC, Welch TD, Shields T, Rubenfire M, Tantry US, Gurbel PA. The effect of St John's Wort on the pharmacodynamic response of clopidogrel in hyporesponsive volunteers and patients: increased platelet inhibition by enhancement of CYP3A4 metabolic activity. J Cardiovasc Pharmacol. 2011 Jan;57(1):86-93. doi: 10.1097/FJC.0b013e3181ffe8d0. PMID: 20980920.

Trivia: St. John's wort plant is named after John the Baptist. The plant blooms around the feast of St. John the Baptist in late June.

Dexmedetomidine and Shivering

Q: Dexmedetomidine can __________ shivering. - Select one

A) exacerbate

B) suppress

Answer: B

Shivering is a common problem in the ICU, particularly post-op patients. Forced-air warming system (Bair Hugger), sedation, meperidine, and occasionally neuromuscular blocking agents (NMBAs) are used.

Dexmedetomidine is less commonly used for this indication, although it can effectively suppress shivering; the patient should be monitored for hypotension and bradycardia.

#surgical-critical-care

References:

1. Shokri M, Bakhtiari Z, Kargar B, Hajialigol A. The Effect of Intravenous Dexmedetomidine During Surgery in the Prevention of Shivering After General Anesthesia in Patients Undergoing Spinal Surgery: A Randomized Clinical Trial. Anesth Pain Med. 2025 May 18;15(2):e159077. doi: 10.5812/aapm-159077. PMID: 40717905; PMCID: PMC12297032.

2. Nesioonpour S, Bayat S, Ghomeishi A, Behaeen K, Savaie M, Ahmadzadeh A. Effect of Intravenous Dexmedetomidine on Shivering in Cesarean Section under Intrathecal Anesthesia: Randomized Clinical Trial. Anesth Pain Med. 2022 Jun 19;12(3):e122735. doi: 10.5812/aapm-122735. PMID: 36818484; PMCID: PMC9923329.

3. Callaway CW, Elmer J, Guyette FX, et al. Dexmedetomidine Reduces Shivering during Mild Hypothermia in Waking Subjects. PLoS One 2015; 10:e0129709.

Death Rattle

Q: An eye drop can help minimize the death rattle.

A) True

B) False

Answer: A

Patients in the end-of-life process lose their ability to clear oral secretions. As air moves over secretions that have pooled in the respiratory tract, the resulting turbulence produces noisy ventilation, known as a death rattle. This can be of great psychological distress to the family, though it does not usually affect the patient.

1% Atropine ophthalmic drops given sublingually can help to minimize the death rattle. The onset of action is about 30 minutes, and it can be given every 2 hours PRN.

Other treatments are:

• Scopolamine patch placed behind the ear once every three days
• Benadryl 25-100 mg every 4 to 6 hours PRN 
• Glycopyrrolate- 400 mcg SC every 8 hours PRN

#palliative-care

#end-of life-care

References:

1. McEvoy T. Atropine: Terminal Respiratory Secretions. Hosp Pharm. 2016 Jan;51(1):39-41. doi: 10.1310/hpj5101-39. Epub 2016 Jan 1. PMID: 38745721; PMCID: PMC11089618.

2. Shinjo T, Okada M. Atropine eyedrops for death rattle in a terminal cancer patient. J Palliat Med. 2013 Feb;16(2):212-3. doi: 10.1089/jpm.2011.0537. Epub 2012 Jun 29. PMID: 22747099.

3. Lokker ME, van Zuylen L, van der Rijt CC, van der Heide A. Prevalence, impact, and treatment of death rattle: a systematic review. J Pain Symptom Manage. 2014 Jan;47(1):105-22. doi: 10.1016/j.jpainsymman.2013.03.011. Epub 2013 Jun 18. PMID: 23790419.

A note on intermittent sigh in mechanical ventilation

Intermittent sigh is rarely used in the ICU during mechanical ventilation. In fact, many trainees do not even know about it! Also, not all ventilator brands can deliver intermittent sigh.

Intermittent sigh is a maneuver of delivering a deep breath once every few minutes. Theoretically, it was practiced under the assumption that it would maintain lung volume, avoid atelectasis, and improve lung compliance. After ARDS network trials showing that low tidal volumes (TV) are lung-protective, intermittent sigh eventually becomes obsolete, given that such high breaths, even once every few minutes or after 6-8 breaths, may cause volutrauma. 

But in 2021, Mauri T. et al. showed that it is at least not harmful and can be considered in selected patients with limited, controlled lower-volume. Oxygenation was improved, whereas tidal volume, respiratory rate, and corrected minute ventilation were lower over the first 7 days from randomization in the sigh vs no-sigh group. Though there was no significant difference in terms of mortality and ventilator-free days for the sigh vs no-sigh group. 

Albert RK et al. in 2023 reported a potentially favourable reduction in 28-day mortality. As a secondary outcome, patients randomized to sighs had 28-day mortality of 11.6% (30/259) vs 17.6% (46/261).

This may be an area still untapped in 'vent. management' and may need further exploration.

#Mechanical-ventilation

#pulmonary

References:

1. Mauri T, Foti G, Fornari C, et al. Sigh in Patients With Acute Hypoxemic Respiratory Failure and ARDS: The PROTECTION Pilot Randomized Clinical Trial. Chest 2021; 159:1426.

2. Albert RK, Jurkovich GJ, Connett J, et al. Sigh Ventilation in Patients With Trauma: The SiVent Randomized Clinical Trial. JAMA 2023; 330:1982.

'poor man test' for septic arthritis

Q: What is the 'poor man's test' for septic arthritis?

Answer: Measuring the strength of synovial fluid leukocyte esterase in the urine "dipstick" test

It is an art to practice Medicine in a resource-limited country(RLC)! Septic arthritis is more common in RLCs. 

Exotic tests like polymerase chain reaction (PCR) or matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectometry may not be available at many places. Aspirating synovial fluid and measuring the strength of synovial fluid leukocyte esterase using a simple urine "dipstick" test, usually available in units/wards, can guide a clinician in initiating antibiotics.

Ideally, synovial fluid and blood cultures x2 should be obtained before starting antibiotics, and synovial fluid should be sent for Gram stain, bacterial culture, white blood cell count with differential, and assessment of crystals (monosodium urate and calcium pyrophosphate crystal deposition) with a polarizing microscope.

Another tip is NOT to rely on synovial fluid glucose, lactate, or pH, as they are very unreliable in septic arthritis.

#ID

#procedures

References: 

1. Aslani H, Pasha Zanoosi MR, Navali AM. Urine Dipstick Leukocyte Esterase in the Rapid Diagnosis of Septic Arthritis. Arch Bone Jt Surg. 2022 Jan;10(1):38-44. doi: 10.22038/ABJS.2021.47573.2334. PMID: 35291247; PMCID: PMC8889425.

2. Mirghaderi P, Pahlevan-Fallahy MT, Mahmoudi J, Mortazavi SMJ. Determining the accuracy of the leukocyte esterase reagent strip test in the rapid diagnosis of adult septic arthritis. Adv Rheumatol. 2024 Aug 30;64(1):65. doi: 10.1186/s42358-024-00409-4. PMID: 39215379.

3. Dey M, Al-Attar M, Peruffo L, et al. Assessment and diagnosis of the acute hot joint: a systematic review and meta-analysis. Rheumatology (Oxford) 2023; 62:1740.

anisocoria

Case: A 22-year-old male is admitted to the ICU with exacerbation of asthma. The patient has been started on intravenous steroids and aerosolized bronchodilators. Medical student reports the finding of unilateral mydriasis (anisocoria).

Discussion: Pharmacologic pupillary changes are very common in the ICU. Commonly used drugs in the ICU may cause mydriasis. It occurs due to different drugs, either by stimulation of the sympathetic innervation of the dilator pupillae or inhibition of the parasympathetic innervation to the sphincter pupillae. These drugs include atropine, homatropine, phenylephrine, clonidine, and glycopyrrolate.

Aerosolized anticholinergic drugs (eg, ipratropium) administered through ventilator masks may produce unilateral mydriasis.

Pharmacologic mydriasis is, by definition, asymptomatic.

# ophthalmology

#pulmonary

#pharmacology

References:

1. Iosson N. Images in clinical medicine. Nebulizer-associated anisocoria. N Engl J Med 2006; 354:e8.

2. Lust K, Livingstone I. Nebulizer-induced anisocoria. Ann Intern Med 1998; 128:327.

3. Openshaw H. Unilateral mydriasis from ipratropium in transplant patients. Neurology 2006; 67:914.

SS in MDMA

Q: A 22-year-old female is admitted to the ICU with a clinical diagnosis of serotonin syndrome (SS) after being found having trismus and 'acting weird' at a dance club on Saturday night. Friends informed about ingesting 'ecstasy' prior to the party. Which concomitant drug is suspected to increase the risk of SS with ecstasy (MDMA)?

Answer: SSRI

Unfortunately, 3,4-methylenedioxymethamphetamine (MDMA), popularly known as ecstasy or Molly, is widely available in society. With the rise of use of Selective Serotonin Reuptake Inhibitors (SSRIs) in society, particularly among college-going students, the concurrent use of MDMA and SSRIs greatly increases the risk of SS. 

MDMA causes SS via stimulation of massive serotonin release. 

#toxicity

#pharmacology

References:

1. Mueller PD, Korey WS. Death by "ecstasy": the serotonin syndrome? Ann Emerg Med 1998; 32:377.

2. Singh AN, Catalan J. Rave drug (ecstasy) and selective serotonin reuptake inhibitor anti-depressants. Indian J Psychiatry. 2000 Apr;42(2):195-7. PMID: 21407935; PMCID: PMC2957712.

3. Dobry Y, Rice T, Sher L. Ecstasy use and serotonin syndrome: a neglected danger to adolescents and young adults prescribed selective serotonin reuptake inhibitors. Int J Adolesc Med Health. 2013;25(3):193-9. doi: 10.1515/ijamh-2013-0052. PMID: 24006318.

NSF and kidney

Q: Patients with a history of a kidney transplant are at risk for nephrogenic systemic fibrosis (NSF) when exposed to gadolinium-based contrast agents (GBCA).

A) True

B) False

Answer: B

Although NSF is a true dreaded complication of GBCA, in various ways, it has been blown out of proportion in clinical practice. Deciding to have GBCA during MRI for patients with kidney dysfunction is always based on clinical judgement for risks vs benefits. Few patients are definitely at high risk and require a nephrologist's consent. In descending order, risk is highest in:

• End-stage kidney disease (ESRD) patients on dialysis of any type
• Acute kidney injury (AKI) 
• eGFR less than 30 mL/min per 1.73 m2

One important point that is often missed is that although a single dose of GBCA can induce NSF, it's usually multiple, cumulative, or higher-than-usual doses of GBCA that are responsible for NSF.

Prior kidney transplant, hepatorenal syndrome, perioperative liver transplantation, exposure to lanthanum carbonate, high-dose erythropoietin treatment, metabolic acidosis, proinflammatory conditions, and elevated iron or phosphate levels were proposed in the past as risk factors for NSF but were found to be unproven.

#nephrology

#radiology

#dermatology

References:

1. Shabana WM, Cohan RH, Ellis JH, et al. Nephrogenic systemic fibrosis: a report of 29 cases. AJR Am J Roentgenol 2008; 190:736.

2. Prince MR, Zhang HL, Roditi GH, et al. Risk factors for NSF: a literature review. J Magn Reson Imaging 2009; 30:1298.

3. Abu-Alfa AK. Nephrogenic systemic fibrosis and gadolinium-based contrast agents. Adv Chronic Kidney Dis 2011; 18:188.

4. Malikova H. Nephrogenic systemic fibrosis: the end of the story? Quant Imaging Med Surg. 2019 Aug;9(8):1470-1474. doi: 10.21037/qims.2019.07.11. PMID: 31559176; PMCID: PMC6732068.

DD in alcohol poisoning

Q: 34 years old patient presents with known ingested alcohol at home. Which of the following toxins may cause cranial nerve palsies and tetany? - select one

A) Ethylene glycol 

B) Methanol 

Answer: A

There is usually no luxury of time in initiating alcohol management. History and clinical exam play a vital role in determining the actual type of alcohol toxicity, particularly if sophisticated, reliable, or fast labs are not available, like in free-standing Emergency Rooms (ERs) and Urgent Cares. 

Cranial nerve palsies and tetany are almost exclusively limited to ethylene glycol toxicity and occur due to oxalate-induced hypocalcemia.

Similarly, an afferent pupillary defect is almost always due to advanced methanol poisoning and demonstrates mydriasis, a retinal sheen (a glossy or metallic reflex) due to retinal edema, and hyperemia of the optic disk.

#toxicity

#physical-exam

#differential-diagnosis

References:

1. Cohen ET, Su MK, Biary R, Hoffman RS. Distinguishing between toxic alcohol ingestion vs alcoholic ketoacidosis: how can we tell the difference? Clin Toxicol (Phila). 2021 Aug;59(8):715-720. doi: 10.1080/15563650.2020.1865542. Epub 2021 Jan 21. PMID: 33475435.

2. Leth PM, Gregersen M. Ethylene glycol poisoning. Forensic Sci Int. 2005 Dec 20;155(2-3):179-84. doi: 10.1016/j.forsciint.2004.11.012. Epub 2005 Jan 21. PMID: 16226155.

3. Alrashed M, Aldeghaither NS, Almutairi SY, Almutairi M, Alghamdi A, Alqahtani T, Almojathel GH, Alnassar NA, Alghadeer SM, Alshehri A, Alnuhait M, Almohammed OA. The Perils of Methanol Exposure: Insights into Toxicity and Clinical Management. Toxics. 2024 Dec 20;12(12):924. doi: 10.3390/toxics12120924. PMID: 39771139; PMCID: PMC11728796.

Cutaneous Lesions

 

Steroids and KS

Q: Steroids _______________ Kaposi Sarcoma (KS)? - select one

A) exacerbates

B) suppresses 

Answer: A

Steroids may induce as well as exacerbate preexisting KS. This is true for HIV, transplant patients, autoimmune disorders, and lymphoproliferative diseases.

HIV patients are particularly at risk as steroid is frequently used in them for immune thrombocytopenia and Pneumocystis jirovecii pneumonia PJC - previous PCP). 

Fortunately, KS lesions regress on reduction or withdrawal of steroids.

Besides steroids, opportunistic infections have also been associated with the induction or exacerbation of preexisting KS due to high levels of proinflammatory cytokines.

#ID

References:

1. Fernández-Sánchez M, Iglesias MC, Ablanedo-Terrazas Y, Ormsby CE, Alvarado-de la Barrera C, Reyes-Terán G. Steroids are a risk factor for Kaposi's sarcoma-immune reconstitution inflammatory syndrome and mortality in HIV infection. AIDS. 2016 Mar 27;30(6):909-14. doi: 10.1097/QAD.0000000000000993. PMID: 26636923; PMCID: PMC4794188.

2. Trattner A, Hodak E, David M, Sandbank M. The appearance of Kaposi sarcoma during corticosteroid therapy. Cancer 1993; 72:1779.

3. Gill PS, Loureiro C, Bernstein-Singer M, et al. Clinical effect of glucocorticoids on Kaposi sarcoma related to the acquired immunodeficiency syndrome (AIDS). Ann Intern Med 1989; 110:937.

Proper handling of SV fluid analysis

Q: Mention at least one precaution that should be taken while evaluating crystals in synovial (SV) fluid analysis.

Answer: Talc-free gloves

Synovial fluid analysis is a delicate process that requires strict precautions when handling the specimen. Talc gloves are still the norm in many countries. Contamination of the slide with birefringent talc particles can make microscopic examination for pathogenetically important crystals difficult. A few other important precautions are:

• Aspiration under aseptic conditions
• Quick transfer of specimen to sterile tubes*
• As early as possible platation
• Avoid contamination of the synovial fluid sample with injectable corticosteroid 
• Either EDTA or heparinized tubes should be used for inflammatory joint fluids, which often contain high fibrinogen and fibrin

* Some experts directly place a drop of fresh synovial fluid on a slide with a cover slip and expedite viewing under a microscope in the lab.

#rheumatology

#pathology

References:

1. Dieppe P, Swan A. Identification of crystals in synovial fluid. Ann Rheum Dis 1999; 58:261.

2. Miller JM, Binnicker MJ, Campbell S, et al. A Guide to Utilization of the Microbiology Laboratory for Diagnosis of Infectious Diseases: 2018 Update by the Infectious Diseases Society of America and the American Society for Microbiology. Clin Infect Dis 2018; 67:e1.

3. Freemont AJ. Microscopic analysis of synovial fluid--the perfect diagnostic test? Ann Rheum Dis 1996; 55:695.

4. Graf SW, Buchbinder R, Zochling J, Whittle SL. The accuracy of methods for urate crystal detection in synovial fluid and the effect of sample handling: a systematic review. Clin Rheumatol 2013; 32:225.

Attrition Bias

Q: What is the usual threshold to be considered as a high rate of attrition in a Randomized Control Trial (RCT)? 

Answer: 20%

Attrition refers to participants dropping out of a study, which can occur in any medical study. Contrary to popular belief, it's not only the participants leaving the study, but it also includes patients who die or are lost to follow-up during the study. 

The authors are obliged to report the level of attrition so readers and critics can assess the validity and bias (attrition bias), and the effect on statistical power and confidence intervals of the (probably skewed) results. Attrition bias may overestimate the results. There is a high probability that participants who leave the study may differ from those who remain or survive during the study period.

A minor level, i.e., up to 5%, is expected in long-term studies, but >20% is considered high. Attrition may occur due to higher mortality, negative experiences, complicated protocols, side effects, logistical issues, relocations, and the length of the study.

#statistics

References:

1. Dumville JC, Torgerson DJ, Hewitt CE. Reporting attrition in randomised controlled trials. BMJ. 2006 Apr 22;332(7547):969-71. doi: 10.1136/bmj.332.7547.969. PMID: 16627519; PMCID: PMC1444839.

2. Nunan D, Aronson J, Bankhead C. Catalogue of bias: attrition bias. BMJ Evid Based Med. 2018 Feb;23(1):21-22. doi: 10.1136/ebmed-2017-110883. PMID: 29367321.

3. Rees JS, Somi S. A guide to the clinical management of attrition. Br Dent J. 2018 Mar 9;224(5):319-323. doi: 10.1038/sj.bdj.2018.169. Epub 2018 Mar 2. PMID: 29495028.

4. Linardon J. Rates of attrition and engagement in randomized controlled trials of mindfulness apps: Systematic review and meta-analysis. Behav Res Ther. 2023 Nov;170:104421. doi: 10.1016/j.brat.2023.104421. Epub 2023 Oct 14. PMID: 37862854.

In mitral valve IE

Q: Which of the leaflets is more prone to embolization in Mitral valve endocarditis (IE)? - select one

A) Anterior

B) Posterior

Answer: A

Vegetation characteristics, including location, play an important role in the risk of embolization in IE. The major risk factors are:

• vegetation size >10 mm 
• vegetation mobility
• vegetation on the anterior leaflet
• prior embolization
• infection with S. aureus, Streptococcus bovis, or fungus

Although cardiac surgical service should be consulted as soon as possible (ASAP!), the importance of starting antibiotics as early as possible is extremely vital, as the risk of embolization tends to decline rapidly after initiation of effective antimicrobial therapy, and becomes uncommon after a week of antibiotics.

#surgical-critical-care

#cardiology

#ID

References:

1. Yanagawa B, Pettersson GB, Habib G, et al. Surgical Management of Infective Endocarditis Complicated by Embolic Stroke: Practical Recommendations for Clinicians. Circulation 2016; 134:1280.

2. Mohananey D, Mohadjer A, Pettersson G, et al. Association of Vegetation Size With Embolic Risk in Patients With Infective Endocarditis: A Systematic Review and Meta-analysis. JAMA Intern Med 2018; 178:502.

3. Weber C, Marin-Cuartas M, Tugtekin SM, Diab M, Saha S, Akhyari P, Elderia A, Muench F, Petrov A, Aubin H, Misfeld M, Lichtenberg A, Hagl C, Doenst T, Matschke K, Borger MA, Wahlers T, Luehr M; Study Group “Clinical, Multicenter Project of Analysis of Infective Endocarditis in Germany” (CAMPAIGN). Aortic and Mitral Valve Endocarditis-Simply Left-Sided Endocarditis or Different Entities Requiring Individual Consideration?-Insights from the CAMPAIGN Database. J Clin Med. 2024 Sep 30;13(19):5841. doi: 10.3390/jcm13195841. PMID: 39407901; PMCID: PMC11477404.

4. Cabezon G, Pulido P, López Díaz J, de Miguel-Álava M, Vilacosta I, García-Azorin D, Lozano A, Oña A, Arenillas JF, San Román JA. Embolic Events in Infective Endocarditis: A Comprehensive Review. Rev Cardiovasc Med. 2024 Mar 7;25(3):97. doi: 10.31083/j.rcm2503097. PMID: 39076945; PMCID: PMC11263858.

Nephrotoxins in AKI

Q: A 62-year-old patient with a past history of hypertension (HTN) and Diabetes Mellitus (DM) is admitted to the ICU with severe community-acquired pneumonia (CAP) and septic shock. Patient required intubation, and in the next 48 hours, went into Acute Kidney Injury (AKI). Which of his following medications should be discontinued? - select one

A) Angiotensin-converting enzyme (ACE) inhibitors

B) Sodium-glucose cotransporter 2 (SGLT2) inhibitors

C) Both A and B

Answer: C

In case of severe illness and AKI, all nephrotoxic meds, like nonsteroidal anti-inflammatory drugs (NSAIDs), should be stopped. Many of these patients are usually on ACE inhibitors, ARBs, and SGLT2 inhibitors - they all should be stopped. 

SGLT2 inhibitors are relatively new agents, and there remains limited understanding about their role. Although they have shown to reduce the rate of AKI, once AKI and severe hemodynamic instability ensues they should be stopped. To date, the scientific evidence is mixed, and the jury is still out on this! 

ACE inhibitors and ARBs, as well as SGLT2 inhibitors, alter the kidney's ability to autoregulate blood flow during AKI and reduce kidney perfusion. This results in exacerbation of hemodynamically mediated AKI. It is rarely appreciated that if ACE inhibitors or ARBs are discontinued in hospital-acquired AKI within the first 48 hours of admission, there is an overall statistically significant 30-day mortality. The only exception is scleroderma renal crisis. 

A few other harmful drugs in AKI that should be stopped are metformin and gabapentin. All renally excreted drugs should be dose-adjusted.

#nephrology

#pharmacology

#endocrinology

References:

1. Nie S, Li Y, Sun Y, et al. Discontinuation of Renin-Angiotensin System Inhibitors during Acute Kidney Injury Episode and All-Cause Mortality: Target Trial Emulation Studies. J Am Soc Nephrol 2025; 36:2410.

2. Nakao Y, Mori M, Mori Y, Bonventre JV. SGLT2 inhibitors and acute kidney injury. Nephrol Dial Transplant. 2026 Jan 30;41(2):243-254. doi: 10.1093/ndt/gfaf132. PMID: 40736512; PMCID: PMC12855603.

3. Dong Z, Mo W, Ling Z, Hou L, Deng T. Efficacy of SGLT2 inhibitors on acute kidney injury in patients with chronic kidney disease, cardiovascular disease, and type 2 diabetes: A meta-analysis. J Natl Med Assoc. 2025 Dec;117(6):458-469. doi: 10.1016/j.jnma.2025.08.110. Epub 2025 Sep 16. PMID: 40962701.

SUP in head trauma

Q: Why are patients with head trauma at increased risk for Gastrointestinal bleed (GIB) and require stress ulcer prophylaxis (SUP)?

Answer: The head trauma patients are usually pointed out in all review articles to be at high risk for GIB in the ICU. The data is decades old, but still applicable. This is due to the pathophysiology of high gastrin stimulation of parietal cells in patients with head trauma. Some clinicians put all ICU patients on SUP, but this practice is flawed and not evidence-based. This practice may expose patients with low or no risk of GIB in the ICU to the risk of nosocomial infections. That said, all patients with risk of stress-related GIB should be placed on SUP till risk exists. 

Discontinuation of SUP is also an important clinical decision for each patient and should be discussed every day.

# neurosurgery

#GI

#patient-safety

References:

1. Bowen JC, Fleming WH, Thompson JC. Increased gastrin release following penetrating central nervous system injury. Surgery 1974; 75:720.

2. Stremple JF, Molot MD, McNamara JJ, et al. Posttraumatic gastric bleeding: prospective gastric secretion composition. Arch Surg 1972; 105:177.

3. Watts CC, Clark K. Gastric acidity in the comatose patient. J Neurosurg 1969; 30:107.

4. McGraw C, Briscoe A, Reynolds C, Carrick M, Palacio CH, Waswick W, Miller A, Trujillo L, Bar-Or D. Outcomes of patients with traumatic brain injury after stress ulcer prophylaxis: a retrospective multicenter study. Trauma Surg Acute Care Open. 2024 Feb 23;9(1):e001285. doi: 10.1136/tsaco-2023-001285. PMID: 38410756; PMCID: PMC10895230.

5. Liu B, Liu S, Yin A, Siddiqi J. Risks and benefits of stress ulcer prophylaxis in adult neurocritical care patients: a systematic review and meta-analysis of randomized controlled trials. Crit Care. 2015 Nov 17;19:409. doi: 10.1186/s13054-015-1107-2. PMID: 26577436; PMCID: PMC4650140.

Defining Neutropenia

Q: Neutropenia is defined as an absolute neutrophil count (ANC) of less than? -select one

A) 500/microL

B) 1500/microL

Answer: B

Neutropenia is defined as an absolute neutrophil count (ANC) of less than 1500/microL. The formula to calculate ANC is 

ANC = WBC (cells/microL) x percent (PMNs + bands) ÷ 100

Where:

WBC = white blood cell count

PMNs = polymorphonuclear cells 

There are various online calculators available.

An ANC below 500 cells/L (choice B) does not define ANC, but at this level, the risk of infection is very high.

The general rule of thumb suggests that if ANC:

• 1000 to 1500/microL = No significant risk of infection; fever can be managed on an outpatient basis
• 500 to 999/microL = Some risk of infection; fever can occasionally be managed on an outpatient basis
• 200 to 499/microL = Significant risk of infection; fever should always be managed on an inpatient basis with parenteral antibiotics, despite few clinical signs of infection
• less than 200/microL = Very significant risk of infection; fever should always be managed on an inpatient basis with parenteral antibiotics, despite few or no clinical signs of infection

The objective of the above question is to identify the common mistakes clinicians make while defining neutropenia.

References:

1. Min KI, Byeon S. Diagnosis and management of neutropenia. Blood Res. 2025 May 26;60(1):30. doi: 10.1007/s44313-025-00079-1. PMID: 40418265; PMCID: PMC12106181.

2. Patel S. Calculated decisions: Absolute neutrophil count. Emerg Med Pract. 2018 Jan 2;20(Suppl 1):1-2. PMID: 29323858.

3. Al-Gwaiz LA, Babay HH. The diagnostic value of absolute neutrophil count, band count and morphologic changes of neutrophils in predicting bacterial infections. Med Princ Pract. 2007;16(5):344-7. doi: 10.1159/000104806. PMID: 17709921.

ICS and voice

Q: Inhaled glucocorticoids (ICS) may cause dysphonia.

A) True

B) False

Answer: A

Unfortunately, dysphonia manifested as a hoarse voice is common among patients who use long-term ICS. It occurs due to laryngeal myopathy, leading to incomplete closure or bowing of the vocal cords during adduction. Other contributing factors are mucosal irritation and frequent laryngeal candidiasis. Fortunately, it is reversible on discontinuation of ICS.

Strategies to keep dysphonia to a minimum are using the lowest ICS dose, using drugs known to cause the least dysphonia, and adjusting technique to decrease laryngeal deposition.

#pulmonary

#pharmacology

References:

1. Roland NJ, Bhalla RK, Earis J. The local side effects of inhaled corticosteroids: current understanding and review of the literature. Chest 2004; 126:213.

2. Buhl R. Local oropharyngeal side effects of inhaled corticosteroids in patients with asthma. Allergy 2006; 61:518.

3. Galván CA, Guarderas JC. Practical considerations for dysphonia caused by inhaled corticosteroids. Mayo Clin Proc 2012; 87:901.

4. Rachelefsky GS, Liao Y, Faruqi R. Impact of inhaled corticosteroid-induced oropharyngeal adverse events: results from a meta-analysis. Ann Allergy Asthma Immunol 2007; 98:225.

Asthma and ACE-I

Q: Asthma patients are more prone to get cough from Angiotensin Converting Enzyme inhibitor (ACE-I).

A) True

B) False

Answer: B

Patients with asthma are not at high risk of developing additional cough, but they may experience increased bronchospasm, so it's still a watchful situation!

A dry hacking cough associated with ACE-I therapy remained an enigma for clinicians. For some reason, females are affected more. It resolves with discontinuation but may recur when challenged with the same ACE-I or a different name. A genetic component is highly suspected.

Interestingly, nonsteroidal antiinflammatory drugs (NSAIDs) and aspirin have shown to decrease or improve the tendency of cough due to ACE-I, but they come with the risk of hyperkalemia, particularly in patients with renal insufficiency.

#pharmacology

#toxicology

#pulmonary

References:

1. Wood R. Bronchospasm and cough as adverse reactions to the ACE inhibitors captopril, enalapril and lisinopril. A controlled retrospective cohort study. Br J Clin Pharmacol 1995; 39:265.

2. Lunde H, Hedner T, Samuelsson O, et al. Dyspnoea, asthma, and bronchospasm in relation to treatment with angiotensin converting enzyme inhibitors. BMJ 1994; 308:18.

3. Tenenbaum A, Grossman E, Shemesh J, et al. Intermediate but not low doses of aspirin can suppress angiotensin-converting enzyme inhibitor-induced cough. Am J Hypertens 2000; 13:776.

4. Ghouse J, Tragante V, Muhammad A, et al. Polygenic risk score for ACE-inhibitor-associated cough based on the discovery of new genetic loci. Eur Heart J 2022; 43:4707.

Indium Scan vs Gallium scan

Q: What is the difference between an Indium Scan and a Gallium scan?

Answer: The indium scan is a procedure in which WBCs (neutrophils) are removed from the patient, tagged with the radioisotope Indium-111, and then injected back into the patient. The tagged leukocytes subsequently enhance areas of relatively new infection, where live neutrophils are still rapidly and actively localizing.

A gallium scan has an advantage over the indium scan because gallium binds to neutrophil membranes, even after neutrophil death. This makes gallium more broadly sensitive, allowing it to localize to other sources of fever, such as chronic infections and tumors.

#nuclear-medicine

#ID

References:

1. Lewis SS, Cox GM, Stout JE. Clinical utility of indium 111-labeled white blood cell scintigraphy for evaluation of suspected infection. Open Forum Infect Dis. 2014 Sep 17;1(2):ofu089. doi: 10.1093/ofid/ofu089. PMID: 25734155; PMCID: PMC4281781.

2. Merkel KD, Brown ML, Dewanjee MK, Fitzgerald RH Jr. Comparison of indium-labeled-leukocyte imaging with sequential technetium-gallium scanning in the diagnosis of low-grade musculoskeletal sepsis. A prospective study. J Bone Joint Surg Am. 1985 Mar;67(3):465-76. PMID: 3919029.

3. Dittrich RP, De Jesus O. Gallium Scan. 2022 Dec 26. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan–. PMID: 33620825.

End-Tidal CO2

Q: Why its called "End-Tidal" CO2?

Answer: It's the point in the respiratory cycle where CO2 is at the highest level (End of the tide)

There are five phases of respiration when it comes to end-tidal Co2 analysis

1. Dead space ventilation
2. Ascending expiratory phase
3. Alveolar Plateau
4. End-tidal CO2
5. Descending inspiratory phase

These five phases are marked in the pic as

A - B: Dead space ventilation

B - C: Ascending expiratory phase

C - D: Alveolar Plateau

D: End-tidal CO2 (highest)

D - E: Descending inspiratory phase

#pulmonary

#procedures

References:

1. Krauss B, Deykin A, Lam A, et al. Capnogram shape in obstructive lung disease. Anesth Analg 2005; 100:884. Copyright © 2005 Lippincott Williams & Wilkins.

2. Zwerneman K. End-tidal carbon dioxide monitoring: a VITAL sign worth watching. Crit Care Nurs Clin North Am. 2006 Jun;18(2):217-25, xi. doi: 10.1016/j.ccell.2006.02.002. PMID: 16728308.

3. Benumof JL. Abnormal end-tidal CO2 waveforms. Can J Anaesth. 2003 Aug-Sep;50(7):754. doi: 10.1007/BF03018728. PMID: 12944461.

Bronchial Sleeve Resection

Q: What is sleeve resection of the lung?

Answer: A sleeve resection is a kind of maximum lung/tissue-sparing surgery, or an alternative to a pneumonectomy. This procedure is performed by removing a lobe containing a target lesion (mostly a tumor) with a portion of the lobar bronchus to an uninvolved lobe. The remaining bronchus to the uninvolved lobe is anastomosed to the remaining proximal airway.

#pulmonary

#surgical-critical-care

References:

1. Deslauriers J, Mehran RJ, Guimont C, Brisson J. Staging and management of lung cancer: sleeve resection. World J Surg. 1993 Nov-Dec;17(6):712-8. doi: 10.1007/BF01659080. PMID: 8109107.

2. Suzuki K. Extended Sleeve Resection for Lung Cancer. Thorac Surg Clin. 2018 Aug;28(3):291-297. doi: 10.1016/j.thorsurg.2018.03.004. PMID: 30054066.

3. Duan J, Cai H, Huang W, Lin L, Wu L, Fan J. Bronchial Sleeve Resection with Complete Pulmonary Preservation: A Single-Center Experience. Cancer Manag Res. 2020 Dec 16;12:12975-12982. doi: 10.2147/CMAR.S286934. PMID: 33364843; PMCID: PMC7751305.

Ventilator mode and sleep in ICU

Q; Which of the ventilator modes has so far shown that it causes more sleep disturbances in the ICU patients? - select one

A) Assist Controlled (AC)

B) Pressure Controlled (PC)

C) Synchronized Intermittent Mandatory Ventilation (SIMV)

Answer: B

Although the data is not robust and the evidence is weak, PC mode has so far shown to cause most sleep disturbances in the ICU. Unfortunately, sedation is not equivalent to a normal sleep cycle in ICU patients.

AC mode is widely believed to be easiest for the patient because it has the least impact on the patient's contribution to ventilation.

Although intensivists are hopeful that future data will show greater promise for other modes, such as Adaptive Support Ventilation (ASV) or Neurally adjusted ventilatory assist (NAVA).

#ventilators

#sleep

References:

1. Parthasarathy S, Tobin MJ. Effect of ventilator mode on sleep quality in critically ill patients. Am J Respir Crit Care Med 2002; 166:1423.

2. Cabello B, Thille AW, Drouot X, et al. Sleep quality in mechanically ventilated patients: comparison of three ventilatory modes. Crit Care Med 2008; 36:1749.

3. Locihová H, Žiaková K. The effects of mechanical ventilation on the quality of sleep of hospitalised patients in the Intensive Care Unit. Rom J Anaesth Intensive Care. 2018 Apr;25(1):61-72. doi: 10.21454/rjaic.7518.251.ven. PMID: 29756065; PMCID: PMC5931186.

Paradoxical Effect of Acetazolamide in the Kidneys and Lungs

Acetazolamide is a carbonic anhydrase inhibitor and is frequently used to treat hypercarbia and metabolic alkalosis. Acetazolamide affects three major organs of the body: the brain, lungs, and kidneys. It is imperative to understand the paradoxical effect of acetazolamide in kidneys and lungs.

In the kidneys, acetazolamide increases hydrogen ion retention and bicarbonate excretion, causing metabolic acidosis over several hours. This also has a secondary effect: metabolic acidosis further increases respiratory drive.

In the lungs, acetazolamide blocks the reciprocal conversion of bicarbonate to CO2 in pulmonary capillaries and impairs the lungs' ability to excrete the CO2. The intended effect is to increase minute ventilation and thereby reduce hypercarbia. But the patients who are not able to increase their ventilation, like patients on ventilators, and, to make it worse, on neuromuscular blockade, may have further deterioration in hypercarbia.

Clinical significance: In the ICU, acetazolamide may 'fire back' if the patient's kidneys are not working well and the patient is on a ventilator. Therefore, it should be used with much greater caution.

Centrally, acetazolamide blocks the CO2 conversion to bicarbonate in tissue capillaries and acutely raises the local tissue partial pressure of carbon dioxide (PCO2). This locally elevated PCO2 and lower pH in the brain increase the central ventilatory drive and lower PaCO2. This central effect, combined with its pulmonary effect, makes acetazolamide an effective prophylactic and therapeutic agent for acute and chronic mountain sickness in healthy individuals.

#pulmonary

#acid-base

References:

1. Swenson ER, Hughes JM. Effects of acute and chronic acetazolamide on resting ventilation and ventilatory responses in men. J Appl Physiol (1985) 1993; 74:230.

2. Richalet JP, Rivera M, Bouchet P, et al. Acetazolamide: a treatment for chronic mountain sickness. Am J Respir Crit Care Med 2005; 172:1427.

3. Alkhuzaee FS, Aldardeer NF, Althobaiti OA, Aljuaid AS, Alshehri AM. Acetazolamide for the Management of Diuretic-Induced Chloride Depletion Alkalosis: A Systematic Review. J Clin Med. 2025 Feb 7;14(4):1041. doi: 10.3390/jcm14041041. PMID: 40004571; PMCID: PMC11857046.

4. Van Berkel MA, Elefritz JL. Evaluating off-label uses of acetazolamide. Am J Health Syst Pharm. 2018 Apr 15;75(8):524-531. doi: 10.2146/ajhp170279. PMID: 29626002.

Wrist BP

Q: Blood Pressure (BP) taken at the wrist level is usually? - select one

A) falsely elevated

B) falsely lowered

Answer: A

Measuring non-invasive BP at the radial artery, i.e., wrist level, is not desirable, though it may be necessary in a few patients, such as those with axillary lymph node resection.

BP at wrist level is falsely elevated due to the hydrostatic pressure related to the lower position of the wrist relative to the heart. Additionally, the relatively small-diameter vessels in older adults are calcified and exhibit reduced elastance. Although BP can be measured with the wrist at heart level, wrist flexion may interfere with sensor positioning.

Wrist BP measurement requires equipment specifically designed for wrist BP, and devices used for brachial BP measurement should not be used.

#hemodynamics

References:

1. Muntner P, Shimbo D, Carey RM, et al. Measurement of Blood Pressure in Humans: A Scientific Statement From the American Heart Association. Hypertension 2019; 73:e35.

2. Palatini P, Asmar R, O'Brien E, et al. Recommendations for blood pressure measurement in large arms in research and clinical practice: position paper of the European society of hypertension working group on blood pressure monitoring and cardiovascular variability. J Hypertens 2020; 38:1244.

3. Zweiker R, Schumacher M, Fruhwald FM, Watzinger N, Klein W. Comparison of wrist blood pressure measurement with conventional sphygmomanometry at a cardiology outpatient clinic. J Hypertens. 2000 Aug;18(8):1013-8. doi: 10.1097/00004872-200018080-00004. PMID: 10953991.