Prospective observational study to evaluate the significance of rapid shallow breathing index rate at extubation for patient undergoing general anaesthesia.

Intubation and extubation are the main concerns of anaesthetist. The process of successful post anaesthesia extubation is a great challenge for the anaesthesiologist working in the operation theater. As an anesthesiologist when we are extubating the surgical patient, three things we keep in our mind (make sure that are fulfilled).1st is patient respiratory muscle power is back to normal so that he can breathe independently without any aid. This is done by normal extubation criteria which are subjective like lifting the head, moving all four limbs etc. and its indirectly indicate that respiratory muscle power is also back to normal. 2nd wakefulness, obeying command, answering by nodding the head, Ramsey sedation score. 3rd hemodynamic stability. All the above three criteria have to be fulfilled before extubation.  Despite several advances in the care of post anaesthesia extubation, failed extubation remains a significant problem faced by the anaesthesiologist that may result into poor patient outcomes. Concerns have been highlighted by different airway societies in their guidelines. Extubation concerns have been well emphasized in the American society of anaesthesiologist closed claims analysis and national audit project 4 (NAP4). The NAP4 report studied the airway-related issues and observed a mortality rate of 5% in patients with extubation failure after general anaesthesia. They reported an incidence of 13% for severe outcomes after extubation failure.

Rapid shallow breathing index (RSBI) is a tool that is use in the weaning of mechanical ventilation in intensive care units. The rapid shallow breathing index (RSBI) is defined as the ratio of respiratory frequency to tidal volume in liter (f/VT). And RSBI rate is defined as sum total of [(RSBI1min – RSBIextubation) / RSBI1min] x 100. The cut-off point of RSBI in an Intensive care unit setup is 105. If the cut-off for the patient is more than 105 the patient is not ready for extubation. This fact has been successfully proved well beyond doubt in intensive care setup as a major tool used for weaning the ventilated patient gradually and keeping them independent of any aid for ventilator. Most Of the existing extubation criteria are subjective except train of four ratio (TOF) which is objective. Its already established gold standard in anaesthesia but for that you Need to purchase peripheral nerve stimulator, electrode cost will be incurred by the patient, might be painful manier time as patient is coming out of anaesthesia, extra work for an anesthetist. While the RSBI is an objective, no any extra machine requirement, easy to calculate, cost free, no extra work involved and not painful. We have kept the TOF ratio constant for all our patients at 0.9 which is an optimum point at which reversal is generally considered. After reversal the conventional, time tested, clinical extubation criteria are assessed.  At this time sequential RSBI at every minute and at extubation RSBI is noted based on this rapid shallow breathing index rate will be calculated. And the time lapse between reversal and extubation is also noted. Recent anaesthesia machines easily display tidal volume and the respiratory rate generated by the patient which makes it easy to calculate RSBI. The RSBI is noninvasive, easy to calculate, no additional cost involved and an objective parameter. This can be a very useful additional tool to existing post anaesthesia extubation criteria.