Increased requirement for minute ventilation and negative arterial to end-tidal carbon dioxide gradient may indicate malignant hyperthermia

Abstract

Characteristic signs of malignant hyperthermia (MH) include unexplained tachycardia, increased end-tidal carbon dioxide (Etco₂) concentration, metabolic and respiratory acidosis, and an increase in body temperature above 38.8°C. We present the case of a patient with highly probable MH. In addition to sinus tachycardia and metabolic and respiratory acidosis, this patient also had a negative arterial to Etco₂ gradient and an increased requirement for minute ventilation to maintain a normal Etco₂ concentration, with signs of increased CO₂ production. Despite these signs of MH, the patient's rectal temperature monitoring equipment did not show an increase in temperature, although the temperature measured in the mouth was increased. This case illustrates the unreliability of measuring rectal temperature as a means of reflecting body temperature during MH and the usefulness of increased CO₂ production signs in helping to diagnose MH.

A Complicated Case of COVID-19 and Hyperglycemic Hyperosmolar Syndrome in an Adolescent Male

“…In the setting of malignant hyperthermia, increased muscle metabolism results in rapid carbon dioxide production. In patients who are not intubated, they can compensate for this by increasing their minute ventilation; but they should not have difficulties oxygenating, which this patient developed [20]. In retrospect, this patient’s initial fever and elevated creatine kinase were most consistent with the early viral syndrome of COVID-19.…”

Mind the gap!!: Reversal of arterial to end-tidal CO2gradient in thoracoscopic bronchogenic cyst excision

“…Other causes are mechanical ventilation with large tidal volumes and low frequency, increased cardiac output and CO 2 production, low functional residual capacity (FRC) and total lung compliance. [ 1 ] Thoracoscopy involves CO 2 insufflation in the thorax for better visualisation and access. If there is a preexisting communication between the pleura and the bronchial tree, there can be direct absorption of CO 2 and falsely high EtCO 2 readings.…”

“…There are reported cases of negative arterial to end-tidal gradient in cases of malignant hyperthermia (MH). [ 1 3 ] The PCO 2 of most alveolar gas is less than PaCO 2 , but in the terminal part of the expirate, the alveolar PCO 2 may increase rapidly towards mixed venous PCO 2 and exceeds PaCO 2 in the presence of MH because a large amount of CO 2 is discharged into the lungs. [ 3 ] In our case, the reasons could be multiple, i.e., bronchopleural communication, and low FRC under anaesthesia.…”