Ultrasound-guided identification of the cricothyroid membrane in a patient with a difficult airway: a case report

Abstract Background Surgical cricothyroidotomy is considered to be the last resort for management of the difficult airway. A major point for a successful surgical cricothyroidotomy is to identify the location of the cricothyroid membrane. Case presentation We encountered a patient with progressive respiratory distress who was anticipated to have a difficult airway due to a large neck abscess. We prepared for both awake intubation and surgical cricothyroidotomy. The cricothyroid membrane could not be identified by palpation, but was readily identified using ultrasound. Conclusion Ultrasound-guided identification of the cricothyroid membrane may be useful in a patient with a difficult airway due to neck swelling

Accuracy of pulse oximeters in detecting hypoxemia in patients with chronic thromboembolic pulmonary hypertension.

Pulse oximetry is routinely used to continuously and non-invasively monitor arterial oxygen saturation (SaO2). When oxygen saturation by pulse oximeter (SpO2) overestimates SaO2, hypoxemia may be overlooked. We compared the SpO2 - SaO2 differences among three pulse oximeters in patients with chronic thromboembolic pulmonary hypertension (CTEPH) who spent their daily lives in a poor oxygen state.This prospective observational study recruited 32 patients with CTEPH undergoing elective cardiac catheterization. As we collected arterial blood samples in the catheter laboratory, SpO2 values were simultaneously recorded. Three pulse oximeters were used on each patient, and SpO2 values were compared with oximetry readings using a blood gas analyzer. To determine the optimal SpO2 value by which to detect hypoxemia (SaO2≦90%), we generated receiver operating characteristic (ROC) curves for each pulse oximeter.The root mean square of each pulse oximeter was 1.79 (OLV-3100), 1.64 (N-BS), and 2.50 (Masimo Radical). The mean bias (SpO2 - SaO2) for the 90%-95% saturation range was significantly higher for Masimo Radical (0.19 +/- 1.78% [OLV-3100], 0.18 +/- 1.63% [N-BS], and 1.61 +/- 1.91% [Masimo Radical]; p<0.0001). The optimal SpO2 value to detect hypoxemia (SaO2≦90%) was 89% for OLV-3100, 90% for N-BS, and 92% for Masimo Radical.We found that the biases and precision with which to detect hypoxemia differed among the three pulse oximeters. To avoid hypoxemia, the optimal SpO2 should be determined for each pulse oximeter

Demographics and laboratory data of the patients.

<p>The demographics and results of blood gas sampling obtained immediately after arterial catheter placement are shown. Data are presented as the means ± SD.</p><p><i>SaO</i>_<i>2</i> oxyhemoglobin saturation measured by blood gas analyzer (ABL 825), <i>PaO</i>_<i>2</i> partial pressure of oxygen in arterial blood, <i>PaCO</i>_<i>2</i> partial pressure of arterial carbon dioxide, <i>Hb</i> hemoglobin</p><p>Demographics and laboratory data of the patients.</p

Calculated biases between SaO₂ (oxyhemoglobin saturation measured by blood gas analyzer [ABL 825]) and SpO₂ (oxyhemoglobin saturation measured by 3 pulse oximeters).

<p>The calculated mean biases (SpO2—SaO2) measured by 3 pulse oximeters for the 85%–100% saturation range are shown. Data are presented as the mean ± SD and analyzed by one-way analysis of variance followed by Tukey’s test.</p><p>*p<0.0001 vs. Nihonkohden OLV-3100 and Nellcor N-BS</p><p>Calculated biases between SaO₂ (oxyhemoglobin saturation measured by blood gas analyzer [ABL 825]) and SpO₂ (oxyhemoglobin saturation measured by 3 pulse oximeters).</p

Calculated biases between SaO₂ (oxyhemoglobin saturation measured by blood gas analyzer [ABL 825]) and SpO₂ (oxyhemoglobin saturation measured by 3 pulse oximeters) among 5 healthy volunteers.

<p>The calculated mean biases (SpO2—SaO2) measured by 3 pulse oximeters are shown. Data are presented as the mean ± SD.</p><p>Calculated biases between SaO₂ (oxyhemoglobin saturation measured by blood gas analyzer [ABL 825]) and SpO₂ (oxyhemoglobin saturation measured by 3 pulse oximeters) among 5 healthy volunteers.</p