Spurious hypoxemia

Pseudohypoxemia From Leukocyte Larceny in a Patient With Chronic Myelogenous Leukemia

Arterial blood gas (ABG) analysis is a generally reliable and frequently employed test for evaluating blood oxygen content. False readings of low oxygen content are rare but can be expected in specific clinical scenarios such as leukemia patients with marked leukocytosis who can develop “leukocyte larceny,” a phenomenon of excess oxygen consumption by leukocytes. Awareness of this phenomenon may lead to early recognition and avoidance of unnecessary diagnostic and therapeutic interventions. This case report presents a patient with marked leukocytosis from chronic myelogenous leukemia whose extubation was briefly delayed due to pseudohypoxemia on ABG measurements.

Hyperleukocytosis Complicated by Intracerebral Hemorrhage and Spurious Hypoxemia: A Case Report and Literature Review

We present the management of a 15-year-old girl with acute myeloid leukemia who presented with massive hyperleukocytosis and neurological deficit due to intracerebral hemorrhage. Surgical intervention was considered but ultimately not undertaken because of the presence of massive hyperleukocytosis, thrombocytopenia, hypokalemia, and considerable discrepancy between the oxygen saturation values determined mechanically and by peripheral oximetry. Aggressive treatment of the hyperleukocytosis was immediately started, which improved the patient's overall condition and rendered surgical intervention unnecessary. This report shows that immediate treatment of massive hyperleukocytosis and critical interpretation of laboratory results in patients with hyperleukocytosis are warranted.

Preanalytical considerations in blood gas analysis

Blood gas testing is a commonly ordered test in hospital settings, where the results almost always have the potential to dictate an immediate or urgent response. The preanalytical steps in testing, from choosing the correct tests to ensuring the specimen is introduced into the instrument correctly, must be perfectly coordinated to ensure that the patient receives appropriate and timely therapy in response to the analytical results. While many of the preanalytical steps in blood gas testing are common to all laboratory tests, such as accurate specimen labeling, some are unique to this testing because of the physicochemical properties of the analytes being measured. The common sources of preanalytical variation in blood gas testing are reviewed here.

[Extreme leucocytosis can lead to an erroneous diagnosis of severe hypoxaemia. Description of a case]

The diagnosis and treatment of respiratory failure is a part of the anaesthesist's daily practice, as well as the hypoxaemia that is one of its physiological and analytical consequences. Patients with an extreme leucocytosis secondary to leukaemia can suffer an incorrect diagnosis of hypoxemia, called "pseudohypoxaemia". This is basically due to the rapid in vitro oxygen consumption, and is characterized by a low partial pressure of oxygen in arterial blood (PaO2) despite a normal oxygen saturation (SpO2) measured by pulse oximetry. Pseudohypoxaemia appears in patients with thrombocytosis or hyper-leucocytosis occurring during blastic crisis of a leukaemia. It must be suspected in patients with a discrepancy between the SpO2 measured by oximetry and the PaO2. In this context, pulse oximetry is the most accurate way to establish the diagnosis and to avoid unnecessary actions. We report the case of a patient with chronic myeloid leukaemia and extreme leucocytosis requiring emergency surgery, and diagnosed with pseudohypoxaemia during the perioperative period that led to a delay in the extubation of the patient.

[Therapeutic of respiratory manifestations at the early phase of acute myeloid leukaemia]

The effective management of the respiratory manifestations at the early phase of acute myeloid hemopathies, especially acute myeloid leukaemia, frequently requires a close collaboration between hematologists, pulmonologists and intensivists. Dominated by infectious etiologies, there are however "specific" disease entities that should not be neglected in the diagnostic and therapeutic approach. These include lung leukostasis, leukemic lung infiltration, the cell lysis pneumopathy and the secondary alveolar proteinosis. These were the subject of a review in the Revue des Maladies Respiratoires published in 2010. We wished to review the management of these clinical situations, the severity of which mean patients frequently require intensive care unit admission. We are only able to make proposals for management here as there is little consensus, except in the metabolic care of tumour lysis syndrome. These data must therefore be reinterpreted regularly as new publications become available.

Myeloproliferative disorders and the hyperviscosity syndrome

Myeloproliferative disorders and the serum hyperviscosity syndrome can rapidly manifest with emergent presentations. Hyperviscosity occurs from pathologic elevations of either the cellular or acellular (protein) fractions of the circulating blood. Classic hyperviscosity syndrome presents with the triad of bleeding diathesis, visual disturbances, and focal neurologic signs. Emergency medicine providers should be aware of these conditions and be prepared to rapidly initiate supportive and early definitive management, including plasma exchange and apharesis. Early consultation with a hematologist is essential to managing these complex patients.

Spurious hypokalaemia and hypophosphataemia due to extreme hyperleukocytosis in a patient with a haematological malignancy

Serious hyperleukocytosis can strongly affect laboratory results of potassium, phosphate and arterial oxygen tension. A 40-year-old woman is presented with an acute myeloid leukaemia and a strongly elevated leukocyte count (310 × 109/L). Apart from this hyperleukocytosis, initial blood tests showed hypokalaemia, hypophosphataemia and serious hypoxaemia without any corresponding complaints. Blood sampled and transported on ice or directly analysed showed no electrolyte abnormalities and hypoxaemia. The observed discrepancy in laboratory results is probably due to the metabolic activity of the leukocytes in vitro. Spurious laboratory results can be a reason for incorrect decisions concerning additional diagnostics and treatment. In conclusion, hyperleukocytosis can cause pseudohypokalaemia, pseudohypophosphataemia and pseudohypoxaemia, which can be prevented by correct sampling and immediate analysis.

Factitious biochemical measurements resulting from hematologic conditions

Factitious laboratory results often lead to unnecessary testing or treatment. This brief review of factitious biochemical results due to preexisting hematologic conditions focuses on the mechanisms underlying the factitious results and suggests ways to prevent them. An observant pathologist identifies these errors, intervenes in a timely fashion, investigates the sources of error diligently, and institutes measures to prevent their recurrence.