Clinical Research Directory

Remifentanil Versus Rocuronium for Optimizing Video Laryngoscopy-assisted Tracheal Intubation

Globally, we are approaching 1 million surgical procedures each day. Tracheal intubation is the mainstay of securing the patient's airway and breathing during general anaesthesia. Approximately 100.000 tracheal intubations are performed annually in Denmark. Airway management remains the primary reason for anaesthesia-related morbidity and mortality. It has been traditionally accepted that best tracheal intubation conditions are obtained by paralysing the patient's muscles, including vocal cords, using a neuromuscular blocking agent (NMBA) such as rocuronium. However, using NBMA may increase the risk of pulmonary complications, intra-operative awareness, in which the patient is paralysed but awake during surgery, anaphylaxis, and re-intubation. In addition, there is a risk of residual neuromuscular blockade postoperatively. In the US, prolonged ventilation and unplanned intubation are the top two most costly perioperative complications. An alternative to NMBA is a large dose of opioids to depress laryngeal reflexes during intubation. The most commonly used non-NMBA modality includes bolus administration of remifentanil. However, remifentanil may cause bradycardia and hypotension. Even short periods of hypotension have been shown to increase the risk of myocardial injury and other serious adverse events such as renal failure, delirium, and even mortality. Evidence also indicates that intubation conditions using only opioids to facilitate intubation, including remifentanil, are inferior to NMBA. However, these trials are underpowered to assess effects on patient-important outcomes and are mostly at high risk of bias. A recent trial has suggested that remifentanil intubation conditions may not be very different. Almost all existing research comparing NMBA to opioids has focused on intubation conditions for direct laryngoscopy using a conventional Macintosh laryngoscopy blade. In recent years, the implementation and availability of the video laryngoscope have grown exponentially and become universal. The video laryngoscope has vastly improved the ease of tracheal intubation, and the number of failed intubations has decreased by two-thirds in Denmark, where a rapid implementation of the video laryngoscope took place. However, limited evidence exists on whether NMBA improves intubation conditions compared to remifentanil when performing video laryngoscope-assisted tracheal intubation.

Developing a Physiology-Pharmacodynamic Model of Rocuronium Dose and Cardiac Output to Investigate the Onset Time of Neuromuscular Relaxation

After a patient is put to sleep, a breathing tube is often placed through the larynx (voice box) into the trachea (windpipe). To place a breathing tube requires the muscles of the jaw, voice box, and diaphragm to be relaxed. This relaxation is usually done with muscle relaxant drugs and called paralysis. Which paralysis drug and what dose should be used has been the subject of many studies. In certain situations it is important for the patient to be fully paralysed before being intubated. Trying to intubate a partially paralysed person may result in coughing that could spread aerosols (e.g. COVID-19), patient desaturation (dropping oxygen levels), greater physiological response to intubation (heart rate, blood pressure and intra-cranial pressure rises) as well as expose the patient to risk of harm through repeated intubation attempts. Current standard practice for patients needing critical care is to use the drug rocuronium at 1-1.2 mg/kg and wait 60 seconds for paralysis to occur. Unfortunately, 1.2mg/kg rocuronium often fails to provide good intubating conditions at 60s in some patients. The early studies revealed that 1 mg/kg rocuronium paralysis at 60s to be 'adequate' rather than 'excellent', as judged by those doing the intubation. One suggestion from 2000, was that a dose of 1.8 - 2.3 mg/kg rocuronium may be required to achieve 'excellent' intubating conditions at 60s in the vast majority of patients as is necessary clinically. The question of whether larger doses might be better has not been further investigated. One of the reasons that the paralysis does not seem to work as fast in some patients may be related to the speed with which the drug travels round the body, pumped around the circulation, to the muscles, by the heart. This speed of circulation called cardiac output can be measured in patients at the time of injection. It may be possible to create a mathematical model for onset of paralysis by combining the information cardiac output, patient size, rocuronium dose administered, and time to paralysis. Such a model has been started by earlier researchers. The model needs further data for completion. Once available, the model may be able to explain how fast the onset of paralysis might be in certain cardiac outputs. It might also deduce whether giving larger doses might help speed up the onset of paralysis in those patients.