Safe Post-op Recovery: The Importance of Respiratory Rate Monitoring

Intermittent monitoring of vital signs on post-operative ward patients is a mainstay of nursing care following surgery. While traditional vital signs such as heart rate, respiratory rate, blood pressure, temperature, and blood oxygen saturation are routinely captured, they may fluctuate substantially throughout the day and night. Utilizing the traditional nursing model of spot-checking vital signs on 4- to 6- or even 12-hour intervals may miss a substantial amount of abnormal vital sign events.^{1, 2}

In a recent interview with Frederic Michard, MD, PhD, a leading expert on post-operative monitoring and safety, he spoke of the importance of respiratory rate monitoring in post-operative ward patients.

Dr. Michard stated,

“Several studies show respiratory rate monitoring is the best predictor of clinical deterioration on the wards since it increases in many conditions like sepsis, acidosis, shock, pneumonia, etc.”

Post-operative patients often require opioids to manage surgical pain on the wards. Overdyk et al. found alarming rates of blood oxygen desaturation events and periods of slow respiratory rate in patients receiving patient-controlled analgesia post-operatively.³ To this point, Dr. Michard suggests,

“Opioid-induced respiratory depression is indeed a classical postoperative complication that could be prevented by more rational use of opioids and that could be detected at an early stage if we were monitoring respiratory rate continuously.”

Dr. Michard went on to describe the shortcomings of intermittent spot-checking of vital signs, pointing out that if a nurse checks on a patient for 5 minutes every 4 hours, that only accounts for 2% of that patient’s time on the ward.

Several technologies already exist that may be used for continuous monitoring of ward patients, however, each solution has its shortcomings. Continuous respiratory rate monitoring may be accomplished using capnographic, acoustic, thoracic impedance or piezo-electric techniques.⁴ Capnographic systems limit mobility by virtue of them requiring a cable connected from the patient to a medical device, while acoustic sensors are better tolerated by patients but may be less accurate during speaking, swallowing as well as other activities awake patients may engage in.⁵ Thoracic impedance monitors are also well tolerated by patients but require multiple electrodes which may become mispositioned leading to incorrect data.⁶ Finally, contact-free piezo-electric sensors are effective for measuring respiratory rate and heart rate but require the patient to remain in bed.⁶

Any continuous monitoring solution must possess high core measurement performance which is crucial in preventing false alarms that can increase the nursing workload substantially and create alarm fatigue, desensitizing nurses to alarms and potentially leading to missed real alerts.⁷ Dr. Michard believes that a major limitation of currently available continuous monitoring solutions is that they limit patient mobility which is in direct opposition to enhanced recovery after surgery (ERAS) protocols calling for early mobility in post-operative patients.

Concerns over the appropriateness of continuous monitoring outside of the intensive care unit (ICU) along with the possibility of increased costs and the need for extensive training have called into question the feasibility of implementing continuous monitoring on the wards. Dr. Michard points out that if the monitoring system is seamless and intuitive, providing a single early warning score sent directly to the appropriate person, workload should not increase but instead be redistributed with more adverse events being managed by ward clinicians and less by critical care specialists.⁷ With regards to cost, continuous monitoring on the wards may generate significant savings associated with a reduction in ICU transfers and hospital lengths of stay.^{8, 9}

Dr. Michard believes that a continuous ward monitoring system must meet specific requirements in order to be effective and successfully implemented by hospitals. In an effort to simplify and promote awareness of the potential benefits of continuous ward monitoring, Dr. Michard has distilled these requirements into the acronym WARD.⁷

W- The monitoring solution must be Wearable and Wireless, promoting comfort and ease of use for ambulatory patients.

A- The monitoring solution must be Accurate and Affordable, able to measure respiratory rate and other vital signs in a way that facilitates hospital adoption.

R- The monitoring solution must be Robust and Reliable, with stable connections between hardware and software leading to early detection of clinical deterioration.

D- The monitoring solution should incorporate Design elements that streamline Data flow adapted to the ward’s unique workflow filtering and fusing Data to decrease alarm burden.

This is an exciting time for post-operative patient safety. Dr. Michard believes that, thanks to recent hardware (wireless sensors) and software (data filtering and fusion, predictive analytics) innovations, it should become possible to adopt continuous ward monitoring without significantly increasing nursing workload.⁷ Dr. Michard states,

“The beauty of these smart algorithms is that they also take into account the trends, the evolution over time and are able to accredit additional points to the deterioration index if they realize that respiratory rate is going up or blood pressure is going down, even if they are not yet in the very abnormal zone.”

These innovations are not only exciting from a technology standpoint but also may lead to a significant reduction in failure to rescue events with an immeasurable positive impact on the lives of patients and their families.

References

1. Postoperative hypoxemia is common and persistent: a prospective blinded observational study. Anesth Analg 2015. Last accessed 11/26/2019.
2. The incidence, severity and detection of blood pressure perturbations after abdominal surgery. Anesthesiology 2019. Last accessed 11/26/2019.
3. Continuous oximetry/capnometry monitoring reveals frequent desaturation and bradypnea during patient-controlled analgesia. Anesth Analg 2007.
4. Digital innovations and emerging technologies for enhanced recovery programmes. Br J Anaesth 2017. Last accessed 11/26/2017.
5. Accuracy of respiratory rate monitoring using a non-invasive acoustic method after general anaesthesia. Brit J Anaesth, 2012. Last accessed 11/26/2019.
6. Early recognition of acutely deteriorating patients in non-intensive care units: assessment of an innovative monitoring technology. J Hosp Med, 2012.
7. Protecting ward patients. ICU Mgmt & Practice, 2019. Last accessed 11/26/2019.
8. Postoperative monitoring – The Dartmouth experience. Anesthesia Patient Safety Foundation Newsletter, 2012. Last accessed 11/26/2019.
9. The return on investment of implementing a continuous monitoring system in general medical-surgical units. Crit Care Med, 2014. Last accessed 11/26/2019.