Working out the expected compensatory response to an acid base disturbance often reveals a second acid-base problem that was otherwise hidden. I regularly use Winter’s formula when I see a metabolic acidosis, but I have trouble remembering the others, so here they are, from Harwood-Nuss’ Clinical Practice of Emergency Medicine (apologies if you ‘think’ in kilopascals): Formulas Describing Expected Compensatory Response to Primary Acid–Base Disturbances Simple Metabolic Acidosis
Predicted decreased PCO2 mm Hg = 1.2 × Δ(HCO3-) mEq/L
Predicted PCO2 mm Hg = 1.5(HCO3-) mEq/L + 8 ± 2
Anticipated PCO2 approximates last two digits of arterial pH
The UK’s National Institute for Health and Clinical Excellence (NICE) has produced guidelines on alcohol-related physical complications, including alcohol withdrawal syndrome, Wernicke’s encephalopathy, acute and chronic pancreatitis, and acute alcoholic hepatitis.
The acute alcohol withdrawal section includes the following recommendations:
Offer drug treatment for the symptoms of acute alcohol withdrawal, as follows:
Consider offering a benzodiazepine or carbamazepine.
Clomethiazole may be offered as an alternative to a benzodiazepine or carbamazepine. However, it should be used with caution, in inpatient settings only and according to the summary of product characteristics.
Follow a symptom-triggered regimen for the drug treatment of acute alcohol withdrawal in people who are:
in hospital or
in other settings where 24-hour assessment and monitoring are available.
Treatment for delirium tremens or seizures
Offer oral lorazepam as first-line treatment for delirium tremens. If symptoms persist or oral medication is declined, give parenteral lorazepam, haloperidol or olanzapine.
For people with alcohol withdrawal seizures, consider offering a quick-acting benzodiazepine (such as lorazepam) to reduce the likelihood of further seizures.
If delirium tremens or seizures develop in a person during treatment for alcohol withdrawal, review their withdrawal drug treatment.
Do not offer phenytoin to treat alcohol withdrawal seizures.
Alcohol-use disorders: Diagnosis and clinical management of alcohol-related physical complications Quick reference summary
Wouldn’t it be great to have a reliable, radiation-free way to diagnose pulmonary embolism? Unfortunately, Magnetic Resonance Angiography is not it. In a study of 371 patients across 7 hospitals from the PIOPED III (Prospective Investigation of Pulmonary Embolism Diagnosis III) investigators, the test was technically inadequate because of poor-quality images in 25% of cases. In those tests that were readable, the sensitivity was only 78%. Gadolinium-Enhanced Magnetic Resonance Angiography for Pulmonary Embolism: A Multicenter Prospective Study (PIOPED III) Ann Intern Med. 2010 Apr 6;152(7):434-43
A case report describes the improvement of a critically ill patient with H1N1 ‘flu after the administration of N-acetylcysteine in a dose similar to that used to treat paracetamol (acetaminophen) overdose.
Influenza virus induces reactive oxygen species that activate nuclear factor kappa B to produce cytokines. High-dose N-acetylcysteine, an antioxidant, is thought to reduce the production of this cytokine storm which contributes to the lethality of influenza. More studies are clearly needed. High-Dose N-Acetylcysteine Therapy for Novel H1N1 Influenza Pneumonia Ann Intern Med. 2010 May 18;152(10):687-8
Steroids are useful in asthma and COPD exacerbations, which are lung problems. Pneumonia is a lung infection, so steroids might help there too right? Erm… no.
A double blind randomised controlled trial demonstrated no benefit from steroids (prednisolone) versus placebo in patients with community acquired pneumonia, and late therapaeutic failure (>72 h after admission) was more common in the prednisolone group. Efficacy of Corticosteroids in Community-acquired Pneumonia: A Randomized Double-Blinded Clinical Trial Am J Respir Crit Care Med. 2010 May 1;181(9):975-82
Investigators at the Royal North Shore Hospital in Sydney (it’s good there) did a literature review to determine the best ‘gold standard’ way of performing a Valsalva manoeuvre for SVT, and assessed success rates before and after its introduction into the ED.
The technique required the patient to lie supine on the bed in a Trendelenberg position, and forcefully expire into a section of suction tubing and pressure gauge for at least 15 seconds and at a pressure of at least 40 mm Hg. The theory behind increased success in a supine position lies in augmenting the patients’ vagal tone and attenuating the sympathetic tone in addition to increased venous return during phase IV of Valsalva. The ‘standardised’ technique improved the rate of successful termination of SVT from 5.3% to 31.7%
Transjugular intrahepatic portosystemic shunt (TIPS) is often used as a rescue therapy in cirrhotic patients with variceal haemorrhage after vasoactive drug therapy and endoscopic ligation have failed. A randomised study compared this standard management with earlier TIPS within 72 hours after randomisation (and randomisation occurred within 24 hours of admission). The early use of TIPS was associated with significant reductions in treatment failure and in mortality.
Not sure what TIPS is? This video I found on YouTube explains it nicely..
[youtube]http://www.youtube.com/watch?v=pGA6KUgq7AI&feature=related[/youtube] Early Use of TIPS in Patients with Cirrhosis and Variceal Bleeding NEJM 2010;362:2370-2379
Image from the amazing Life in the Fast Lane website - click here to visit
A ‘BestBET‘ from the Emergency Medicine Journal examined the evidence for the use of sodium bicarbonate and/or mannitol in the management of rhabdomyolysis.
The clinical bottom line: there is no quality published evidence that alkaline diuresis is a superior treatment to normal saline alone. Rhabdomyolysis and the use of sodium bicarbonate and/or mannitol Emerg Med J. 2010 Apr;27(4):305-8 Full Text at the BestBets site
A Cochrane review examined the evidence from randomised controlled trials to establish whether routine use of inhaled oxygen in acute myocardial infarction (AMI) improves patient-centred outcomes, the primary outcomes being death, pain and complications.
Three trials involving 387 patients were included and 14 deaths occurred. The pooled relative risk (RR) of death was 2.88 (95% CI 0.88 to 9.39) in an intention-to-treat analysis and 3.03 (95% CI 0.93 to 9.83) in patients with confirmed AMI. While suggestive of harm, the small number of deaths recorded meant that this could be a chance occurrence. Pain was measured by analgesic use. The pooled RR for the use of analgesics was 0.97 (95% CI 0.78 to 1.20).
There is therefore no conclusive evidence from randomised controlled trials to support the routine use of inhaled oxygen in patients with acute AMI. A definitive randomised controlled trial is required. Oxygen therapy for acute myocardial infarction Cochrane Review
Vicki Noble’s Emergency Ultrasound team describe the resolution of Songraphic B lines on the lung ultrasound of a patient with end stage renal disease who presented with dyspnoea due to pumonary oedema which was treated with CPAP.
B-lines are hyperechoic vertical lines that originate at and slide with the pleura and extend radially to the edge of the screen without fading. Isolated B-lines may be seen in normal lungs, but diffuse B-lines in multiple zones indicate interstitial thickening, most commonly seen in congestive heart failure (CHF). Image from cardiovascularultrasound.com
This case is interesting because it describes real-time resolution of B-lines during therapy in the ED demonstrating that in CHF, B-lines reflect acute rather than chronic changes within lung parenchyma. Real-time resolution of sonographic B-lines in a patient with pulmonary edema on continuous positive airway pressure Am J Emerg Med. 2010 May;28(4):541.e5-8
