Bedside Pulmonary Rehabilitation – Mandatory and Cost- Effective Tools

Introduction

The diaphragm and chest wall compliance comes down as a result of the respiratory effects of general anesthesia, which significantly reduces the thoracic volume and functional residual capacity (FRC). Even though the lung volume which has decreased is typically clinically minor, it promotes atelectasis. Atelectasis develops in the dependent lung regions, as a result of this decreased compliance, diminished regional ventilation, and retained airway secretions, and it lasts longer than 24 hours in 50% of patients. As a result, higher shunt fraction and V/ Q mismatching may cause arterial hypoxemia. Because atelectasis reduces lung volume, inspiration-expiration cycles start at a lower FRC, which increases the work of breathing. Clearing mucus plugs and secretions with a good cough can encourage the recruitment of collapsing alveoli [1, 2]. However, the reduction in lung volume can affect one’s ability to breathe deeply and cough strongly, as indicated by vital capacity (VC).

Low-flow anesthesia is chosen over high-flow for many reasons, including being more affordable and lowering theatre pollution. It has also been shown to be effective in reducing mucus blockage and the subsequent collapse of alveoli. The first second of expiration’s forced expiratory volume (FEV1) and forced vital capacity (FVC)  which were lower in high-flow anesthetic groups, were used to demonstrate this effect earlier [3]. To prevent respiratory difficulties in the immediate postoperative period, maximum sustained inspiration (MSI) with a respirometer is advised. However, the execution of this maneuver depends on VC, which can be compromised by atelectasis that already exists.

Vital capacity (VC) and inspiratory reserve volume (IRV) measurement is a quick and easy way to keep track of pulmonary functions following surgery. Numerous studies on the effects of high-flow and low-flow on pulmonary functions produced contradictory or ambiguous results [3, 4]. Spirometry has been proven to be a reliable method for measuring FVC and FEV1 measurements of lung function. Even with atelectasis present, the spo2 was maintained between the high-flow and low-flow groups, demonstrating that the Alveolar exchange currently available is sufficient to maintain oxygenation. [4] Since tidal volumes tend to decrease following abdominal procedures, incentive spirometry (IS) (Figure 1) encourages patients to breathe for longer periods in order to cause the lungs to expand. Consequently, IS can be used as an easy way to track lung function, in particular IRV, during spontaneous breathing after surgery. Peak expiratory flow meters (PEFR) are used to identify atelectasis-related obstructions and patients’ maximum effort during forceful exhalation. It serves as a gauge of adequate lung function in the immediate aftermath of surgery. Few studies have been conducted on the effects of anesthesia and atelectasis on Vital Capacity.

Click to enlarge

The maximum flow rate produced during a forceful exhalation, beginning with full lung inflation, is known as the peak expiratory flow rate (PEFR). PEFR depicts significant airway flow and depends on the patient’s willpower and physical prowess. It has been shown that the PEFR and the forced expiratory volume over 1s correlate well (FEV1). Spirometric maneuvers like IRV, VC, and PEFR and its measurement become easier and more efficient tools in preventing postoperative lung complications in patients undergoing anaesthesia [5]. In a hospital setting like the preoperative assessment room, surgical/ medical ward, and postoperative ward, we recommend Inspiratory spirometry and a Peak flow meter (Figure 2) to be available. They are cost-effective and easily usable. It doesn’t need a skilled medical professional to describe the performance. Several methods of respiratory physiotherapy include inspiratory muscle training and preoperative spirometric exercises.

Click to enlarge

Conclusion

It is recommended that simple incentive spirometry and peak flow meter are valuable tools to prepare a patient’s pulmonary functions and to prevent further pulmonary complications. It reduces hospital stays when started preoperatively. It prevents oxygen consumption in the immediate post-operative period. Oxygen requirement was predominantly less when used judiciously.