Letter to the Editor: Lidocaine-Based Local Anesthesia Is Essential During Radial Arterial Puncture for Arterial Blood Gas Sampling in a High-Altitude Environment

To the Editor:

Whether to administer local anesthesia before arterial puncture for arterial blood sampling is currently controversial. Furthermore, there is no documentation suggesting that local anesthetic can be given in a high-altitude setting before the artery puncture.

To begin a military assignment, a 20-year-old male soldier ascended from 500 m to 4,010 m in 6 hours, taking a 2-hour flight and a 4-hour bus ride. He experienced headache, dizziness, anorexia, weakness, coughing, shortness of breath, and a fluttering sensation in his chest on the second day. He was tachypneic (22 breaths/min), tachycardic (120 beats/min), febrile (38.0°C), normotensive (118/81 mmHg), and severely hypoxic (SpO₂, 66% on room air). He was really nervous, yet he was awake and aware. His lips were cyanotic. Harsh breath sounds were heard bilaterally with rales at both lung bases and a third heart sound at the heart apex.

Based on the 2018 Lake Louise Acute Mountain Sickness Score system (Roach et al., 2018), the soldier’s total score was seven points. Considering the symptoms, the patient may be diagnosed with severe acute mountain sickness (high-altitude pulmonary edema), pulmonary infection, respiratory failure, etc. To establish a definitive diagnosis, further tests are required, with arterial blood gas testing being one of the most critical tests.

The nurse explained to the patient why he needed the arterial blood gas testing, the procedure of an arterial sample collection, and the potential risks of arterial puncture. He signed the informed written consent but still felt nervous. The modified Allen test was used to assess collateral circulation to the left hand, and the patient’s test result was positive. The nurse cleaned the puncture site. Using a disposable arterial blood collection device (BD Preset^TM, equipped with a 22 G needle; Becton, Dickinson and Company, Plymouth, UK), the nurse’s attempt to puncture the radial artery was unsuccessful, despite the reorientation of the needle. Due to pain, the patient experienced a vasovagal reaction. The nurse reassured the patient, and after a short rest, the patient’s vasovagal reaction disappeared. The nurse then tried puncturing the patient’s brachial and femoral arteries, but the patient experienced a vasovagal reaction again, and neither puncture was successful.

A cardiologist patiently calmed the soldier again. He applied local anesthesia before puncturing the artery, opting to use the left radial artery and sterilizing it once again. After injecting 0.2 ml of 2% lidocaine hydrochloride injection (CSPC, China) subcutaneously into the radial artery pulsation, about 1.5 cm above the transverse carpal tunnel, the cardiologist successfully performed the puncture, and the specimen was collected. The patient did not report any further pain or experience a vasovagal reaction.

Studies have shown that local anesthesia before a puncture is effective in relieving pain (Gonella et al., 2022) and reducing the time needed to complete the procedure and puncture attempts. Contrary findings have been reported as well. In clinical practice standards for arterial blood gas analysis in adults (second edition), local anesthesia at the point of puncture is not recommended to avoid further puncture failure, even if the patient experiences vasospasm that results in a failed puncture (Sun and Li, 2022). In Chinese hospitals today, arterial blood gas sampling is usually performed without the need of local anesthetic beforehand.

As West China develops, many people, particularly Chinese youth, ascend to high altitudes for various activities (e.g., work, military operations, travel). However, exposure to high altitudes, especially with rapid ascent, may induce severe acute high-altitude disease. Arterial blood gas analysis is crucial for critically ill patients (e.g., acute pulmonary edema) but factors like dehydration and vasospasm can lead to failure of arterial puncture (Latham et al., 2014). Lidocaine can help with pain during the puncture and improve success (Kong et al., 2022). Based on our existing clinical practice, using a 1-ml disposable syringe (HD, Jiangxi, China) fitted with a relatively narrow needle (26 G), local anesthesia with 2% lidocaine before arterial blood gas sampling can reduce the pain perception of the patient and shorten the time of sampling, which is worthwhile to be implemented in critically ill patients in a high-altitude environment. It would be beneficial to do a randomized controlled trial on this method in a high-altitude setting in the future.