The number of elderly patients (>80 years) is increasing and a large proportion of these patients will require surgery and anaestheasia within the next decades.

During anaesthesia NMBAs are used to facilitate tracheal intubation, from former studies it is reported that elderly patients are more sensitive towards muscle relaxants.

It is unknown if there are differences in onset times of NMBAs between younger patients and elderly.

The aim of this study is to determine the onset time, duration of action and effect on intubating conditions for rocuronium 0.6 mg/kg in patients aged 18-40 years and in patiens >80 years. The hypothesis of this study is that rocuronium administered in elderly patients (>80 years) has a longer onset time compared to younger patients.

The number of elderly patients (>80 years) is increasing and a large proportion of these patients will require surgery and anesthesia within the next decades. Elderly patients are at higher risk of major morbidity and mortality and are characterized by a reduction in cardiac output, liver function and renal function. These physiological changes influence pharmacodynamics and pharmacokinetics of drugs administered during anesthesia as for example neuromuscular blocking agents (NMBA).

During anesthesia NMBAs are used to facilitate tracheal intubation, establish muscle relaxation and suppress reflexes during surgery. Elderly patients are more sensitive towards muscle relaxants. In addition studies have reported prolonged duration of NMBAs and an observational study found that elderly patients are more prone to experience residual neuromuscular blockade in the post anesthesia care unit. However, most studies have been conducted in elderly below 80 years.

It is unknown if there are differences in onset times of NMBAs e.g. rocuronium, mivacurium and cisatracurium between younger patients and elderly. Onset time for NMBAs in the elderly is of importance since it may influence intubating conditions, especially during rapid sequence induction. For example it is unknown in the elderly if an increased dose of NMBA reduces the onset time. There remains a need for studies investigating the optimal dose for facilitating intubation in the elderly, both during rapid sequence induction and during elective procedures.

The aim of this study is to determine the onset time, duration of action and effect on intubating conditions for rocuronium 0.6 mg/kg in patients aged 18-40 years and in patients with age > 80 years. The hypothesis of this study is that rocuronium administered in elderly patients (>80 years) has a longer onset in the elderly compared to younger patients.

Inclusion Criteria:

• Patients > 18 years old
• Informed consent
• Scheduled for elective surgery (>1 hour) under general anaesthesia with intubation and use of rocuronium.
• American Society of Anaesthesiologists (ASA) physical status classification I to III
• Can read and understand Danish

Exclusion Criteria:

• Known allergy to rocuronium
• Neuromuscular disease that may interfere with neuromuscular data
• Indication for rapid sequence induction

32 patients Group young: 16 patients age between 18-40 years receiving rocuronium 0.6 mg/kg Group elderly: 16 patients age >80 years receiving rocuronium 0.6 mg/kg

From induction of anesthesia to departure from the operating room.

In both groups the patients will receive rocuronium in a dose aiming to provide optimal intubating conditions. It is not regarded as a disadvantage to use rocuronium, since the effect is monitored through surgery and if needed fully reversed by a reversal agent upon end of surgery.

It is an observational study why the patients mortality was not affected by the trial. Furthermore, patients at high risk for serious adverse events were excluded due to the criteria.