Implementation of a novel postoperative monitoring system using automated Modified Early Warning Scores (MEWS) incorporating end-tidal capnography

Early Warning Systems for Critical Illness Outside the Intensive Care Unit

Early warning systems (EWSs) are designed and deployed to create a rapid assessment and response for patients with clinical deterioration outside the intensive care unit (ICU). These models incorporate patient-level data such as vital signs and laboratory values to detect or prevent adverse clinical events, such as vital signs and laboratories to allow detection and prevention of adverse clinical events such as cardiac arrest, intensive care transfer, or sepsis. The applicability, development, clinical utility, and general perception of EWS in clinical practice vary widely. Here, we review the field as it has grown from early vital sign-based scoring systems to contemporary multidimensional algorithms and predictive technologies for clinical decompensation outside the ICU.

Safer and more efficient vital signs monitoring protocols to identify the deteriorating patients in the general hospital ward: an observational study

Background

The frequency at which patients should have their vital signs (e.g. blood pressure, pulse, oxygen saturation) measured on hospital wards is currently unknown. Current National Health Service monitoring protocols are based on expert opinion but supported by little empirical evidence. The challenge is finding the balance between insufficient monitoring (risking missing early signs of deterioration and delays in treatment) and over-observation of stable patients (wasting resources needed in other aspects of care).

Objective

Provide an evidence-based approach to creating monitoring protocols based on a patient's risk of deterioration and link these to nursing workload and economic impact.

Design

Our study consisted of two parts: (1) an observational study of nursing staff to ascertain the time to perform vital sign observations; and (2) a retrospective study of historic data on patient admissions exploring the relationships between National Early Warning Score and risk of outcome over time. These were underpinned by opinions and experiences from stakeholders.

Setting and participants

Observational study: observed nursing staff on 16 randomly selected adult general wards at four acute National Health Service hospitals. Retrospective study: extracted, linked and analysed routinely collected data from two large National Health Service acute trusts; data from over 400,000 patient admissions and 9,000,000 vital sign observations.

Results

Observational study found a variety of practices, with two hospitals having registered nurses take the majority of vital sign observations and two favouring healthcare assistants or student nurses. However, whoever took the observations spent roughly the same length of time. The average was 5:01 minutes per observation over a 'round', including time to locate and prepare the equipment and travel to the patient area. Retrospective study created survival models predicting the risk of outcomes over time since the patient was last observed. For low-risk patients, there was little difference in risk between 4 hours and 24 hours post observation.

Conclusions

We explored several different scenarios with our stakeholders (clinicians and patients), based on how 'risk' could be managed in different ways. Vital sign observations are often done more frequently than necessary from a bald assessment of the patient's risk, and we show that a maximum threshold of risk could theoretically be achieved with less resource. Existing resources could therefore be redeployed within a changed protocol to achieve better outcomes for some patients without compromising the safety of the rest. Our work supports the approach of the current monitoring protocol, whereby patients' National Early Warning Score 2 guides observation frequency. Existing practice is to observe higher-risk patients more frequently and our findings have shown that this is objectively justified. It is worth noting that important nurse-patient interactions take place during vital sign monitoring and should not be eliminated under new monitoring processes. Our study contributes to the existing evidence on how vital sign observations should be scheduled. However, ultimately, it is for the relevant professionals to decide how our work should be used.

Study registration

This study is registered as ISRCTN10863045.

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Health and Social Care Delivery Research programme (NIHR award ref: 17/05/03) and is published in full in Health and Social Care Delivery Research; Vol. 12, No. 6. See the NIHR Funding and Awards website for further award information.

Clinical decision support for intervention reduction in neonatal patients: A usability assessment

Objective

This study investigated how effectively simplified cognitive walkthroughs, performed independently by four nonclinical researchers, can be used to assess the usability of clinical decision support software. It also helped illuminate the types of usability issues in clinical decision support software tools that cognitive walkthroughs can identify.

Method

A human factors professor and three research assistants each conducted an independent cognitive walkthrough of a web-based demonstration version of T3, a physiologic monitoring system featuring a new clinical decision support software tool called MAnagement Application (MAP). They accessed the demo on personal computers in their homes and used it to walk through several pre-specified tasks, answering three standard questions at each step. Then they met to review and prioritize the findings.

Results

Evaluators acknowledged several positive features including concise, helpful tooltips and an informative column in the patient overview which allows users direct (one-click) access to protocol eligibility and compliance criteria. Recommendations to improve usability include: modify the language to clarify what user actions are possible; visually indicate when eligibility flags are snoozed; and specify which protocol's data is currently being shown.

Conclusion

Independent, simplified cognitive walkthroughs can help ensure that clinical decision support software tools will appropriately support clinicians. Four researchers used this technique to quickly, inexpensively, and effectively assess T3's new MAP tool, which suggests positive actions, such as removing a patient from a ventilator. Results indicate that, while there is room for usability improvements, the MAP tool may help reduce clinician's cognitive load, facilitating improved care. The study also confirmed that cognitive walkthroughs identify issues that make clinical decision support software hard to learn or remember to use.

Examining Causes and Prevention Strategies of Adverse Events in Deceased Hospital Patients: A Retrospective Patient Record Review Study in the Netherlands

OBJECTIVE

To improve patient safety and possibly prevent mortality from adverse events (AEs) in hospitals, it is important to gain insight in their underlying causes. We aimed to examine root causes and potential prevention strategies of AEs in deceased hospital patients.

METHODS

Data on 571 AEs were used from two retrospective patient record review studies of patients who died during hospitalization in the Netherlands. Trained reviewers assessed contributing factors and potential prevention strategies. The results were analyzed together with data on preventability of the AE and the relationship of the AE with the death of the patient.

RESULTS

In 47% of the AEs, patient-related causes were identified, in 35% human causes, in 9% organizational causes, and in 3% technical causes. Preventable AEs were caused by technical, organizational, and human causes (78%, 74%, and 74%, respectively) more often than by patient-related causes (33%). In addition, technical factors caused AEs leading to preventable death (78%) relatively often. Recommended strategies to prevent AEs were quality assurance/peer review, evaluation of safety behavior, improving procedures, and improving information and communication structures.

CONCLUSIONS

Human failures played an important role in the causation of AEs in Dutch hospitals, because they occurred frequently and they were frequently the cause of preventable AEs. To a lesser extent, latent organizational and technical factors were identified. Patient-related factors were often identified, but the preventability of the AEs with these causes was low. For future research into causes of AEs, we recommend combining record review with interviewing.

Assessment of Respiratory Function in Infants and Young Children Wearing Face Masks During the COVID-19 Pandemic

IMPORTANCE

Face masks have been associated with effective prevention of diffusion of viruses via droplets. However, the use of face masks among children, especially those aged younger than 3 years, is debated, and the US Centers for Disease Control and American Academy of Physicians recommend the use of face mask only among individuals aged 3 years or older.

OBJECTIVE

To examine whether the use of surgical facial masks among children is associated with episodes of oxygen desaturation or respiratory distress.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was conducted from May through June 2020 in a secondary-level hospital pediatric unit in Italy. Included participants were 47 healthy children divided by age (ie, group A, aged ≤24 months, and group B, aged >24 months to ≤144 months). Data were analyzed from May through June 2020.

INTERVENTIONS

All participants were monitored every 15 minutes for changes in respiratory parameters for the first 30 minutes while not wearing a surgical face mask and for the next 30 minutes while wearing a face mask. Children aged 24 months and older then participated in a walking test for 12 minutes.

MAIN OUTCOMES AND MEASURES

Changes in respiratory parameters during the use of surgical masks were evaluated.

RESULTS

Among 47 children, 22 children (46.8%) were aged 24 months or younger (ie, group A), with 11 boys (50.0%) and median (interquartile range [IQR]) age 12.5 (10.0-17.5) months, and 25 children (53.2%) were aged older than 24 months to 144 months or younger, with 13 boys (52.0%) and median (IQR) age 100.0 (72.0-120.0) months. During the first 60 minutes of evaluation in the 2 groups, there was no significant change in group A in median (IQR) partial pressure of end-tidal carbon dioxide (Petco2; 33.0 [32.0-34.0] mm Hg; P for Kruskal Wallis = .59), oxygen saturation (Sao2; 98.0% [97.0%-99.0%]; P for Kruskal Wallis = .61), pulse rate (PR; 130.0 [115.0-140.0] pulsations/min; P for Kruskal Wallis = .99), or respiratory rate (RR; 30.0 [28.0-33.0] breaths/min; P for Kruskal Wallis = .69) or for group B in median (IQR) Petco2 (36.0 [34.0-38.0] mm Hg; P for Kruskal Wallis = .97), Sao2 (98.0% [97.0%-98.0%]; P for Kruskal Wallis = .52), PR (96.0 [84.0-104.5] pulsations/min; P for Kruskal Wallis test = .48), or RR (22.0 [20.0-25.0] breaths/min; P for Kruskal Wallis = .55). After the group B walking test, compared with before the walking test, there was a significant increase in median (IQR) PR (96.0 [84.0-104.5] pulsations/min vs 105.0 [100.0-115.0] pulsations/min; P < .02) and RR (22.0 [20.0-25.0] breaths/min vs 26.0 [24.0-29.0] breaths/min; P < .05).

CONCLUSIONS AND RELEVANCE

This cohort study among infants and young children in Italy found that the use of facial masks was not associated with significant changes in Sao2 or Petco2, including among children aged 24 months and younger.

Effects of capnometry monitoring during recovery in the post-anaesthesia care unit: a randomized controlled trial in adults (CAPNOSSPI)

PURPOSE

Continuous capnography should be used on patients admitted to post-anaesthesia care units (PACUs) with endotracheal tubes, but this monitoring is not always performed. Optimized ventilation in the PACU could be part of the global standards of practice to maintain the benefits of perioperative ventilation. The main objective was to study the rate of patients with alveolar hypoventilation before tracheal extubation or Laryngeal Mask Airway (LMA) removal upon the measurement of continuous capnography.

METHODS

In this prospective, parallel-group, randomized controlled study, we enrolled adult patients admitted to the PACU after general anaesthesia with an endotracheal tube or LMA in place. Patients were randomly assigned to two groups: in the Capno + group, nurses managed the patients with access to the capnometer and end-tidal carbon dioxide pressure (PETCO₂) measurements; in the Capno- group, nurses monitored the patients without seeing PETCO₂ measurements. The primary outcome was the percentage of patients with PETCO₂ measurements above 45 mm Hg during the minute before extubation. Secondary endpoints included the delay in recovering spontaneous breathing, rate of hypoxemia, delay before extubation, and length of stay in the PACU.

RESULTS

Forty-eight patients were randomized into the two groups. The percentage of patients with PETCO₂ > 45 mm Hg the minute before extubation was significantly decreased in the Capno + group (83.3% versus 54,1% in the Capno- and Capno + groups respectively, p = 0.029). There were no significant differences concerning secondary endpoints.

CONCLUSIONS

The use of PETCO₂ monitoring improves patient safety by decreasing the incidence of CO₂ retention during recovery from general anaesthesia. This study suggests that this monitoring should be integrated in the PACU. The risk of hypoxemia can also be prevented through the early recognition of apnoea.Clinical Trial registry: clinicaltrial.gov. identifier: NCT03370081.

Update on early warning scores

Early warning scores (EWS) have the objective to provide a preventive approach for detecting those patients in general wards at risk of deterioration before it begins. Well implemented and combined with a tiered response, the EWS expect to be a relevant tool for patient safety. Most of the evidence for their use has been published for the general EWS. Their strengths, such as objectivity and systematic response, health provider training, universal applicability and automatization potential need to be highlighted to counterbalance the weakness and limitations that have also been described. The near future will probably increase availability of EWS, reliability and predictive value through the spread and acceptability of continuous monitoring in general ward, its integration in decision support algorithms with automatic alerts and the elaboration of temporal vital signs patterns that will finally allow to perform a personal modelling depending on individual patient characteristics.

A Pilot Study of End-Tidal Carbon Dioxide in Prediction of Inhospital Cardiac Arrests

A validated means to predict inhospital cardiac arrest is lacking. The purpose of this study was to evaluate the changes in end-tidal carbon dioxide, as it correlates with the progression to inhospital cardiac arrest in ICU patients.

Detection of deteriorating patients after Whipple surgery by a modified early warning score (MEWS)

Background

The modified early warning score (MEWS) was set up to supply prompt recognition of clinically deteriorating patients before they undergo a severe and life-threatening event. The study aimed to describe the probable usefulness of the MEWS in identifying deteriorating post-Whipple patients in hospital wards.

Methods

We performed a study to analyze the relationship between the vital parameters and postoperative severe adverse events of patients after Whipple surgery in Guangdong Provincial People's Hospital from 2000 to 2017. In the retrospective study, a total of 13,651 sets of vital parameters in 236 Whipple postoperative patients were included. Subsequently, we applied a MEWS scoring system and explored the accuracy of the MEWS in evaluating the patients' final events versus advanced mathematical models. We then put the MEWS into the ward warning system and confirmed the accuracy of the MEWS based on the results of prospective studies again.

Results

We assessed the ability of the MEWS to predict postoperative complications with an accuracy rate of 90.86-91.23%, a sensitivity of 83.04-90.88%, and a specificity of 90.85-95.73%.

Conclusions

The MEWS model was applied to identify post-Whipple patients at risk of complication. Once the MEWS ≥2, interventions were needed to minimize the adverse events. Our data suggest that the MEWS is comparable to the advanced mathematical models, but MEWS is more accessible to perform and more generally applicable.

Perioperative intensive care medicine

Surgery represents one of the main therapeutic references in the world, affording greater survival and life expectancy for many patients. In general, the estimated postoperative mortality is low (around 1-4%). Thirteen percent of the surgical procedures have a high risk of complications, accounting for 80% of all postoperative deaths. Recently, there have been significant advances related to organizational aspects, new anesthetic and surgical techniques, prognostic scales, perioperative management and greater participation and involvement of the patient. This new series of Medicina Intensiva will address fundamental aspects of how Departments of Intensive Care Medicine can add value to the surgical process, in a coordinated manner with other services. Institutional policies are required to ensure the detection of patients at risk in hospitalization wards, with early admission to the ICU of those patients in whom admission is indicated, adapting the treatment in the ICU and optimizing the criteria for discharge. The detection and prevention of post-ICU syndrome in patients and relatives, and the follow-up of ICU discharge and hospitalization in a multidisciplinary manner can reduce the sequelae among critical surgical patients, improving the outcomes and quality of life, and restoring the patient to society. In future publications of this series directed to the surgical patient, updates will be provided on the perioperative management of some of the most complex surgeries.

Using the capnogram to assess pulmonary perfusion during a lobectomy: case studies

Capnography is an effective and non-invasive method for monitoring patients during general anesthesia and can reflect the changes in both the respiratory function as well as the circulatory function. In this paper, we present four cases of lobectomy in which we observed a "chair-like" waveform on performing capnography after the surgery. In all the cases, the appearance of this "chair-like" waveform led to the suspicion of a blockage in the pulmonary artery perfusion, which was then confirmed to be an obstruction in the pulmonary artery on further investigation. This suggests that during lobectomy, capnography can help confirm that the pulmonary circulation is unobstructed. We believe that it is very important to observe the changes of end-tidal carbon dioxide pressure and capnogram during one-lung ventilation, particularly in cases of pulmonary artery anastomosis.

Journal of Clinical Monitoring and Computing 2017 end of year summary: respiration

This paper reviews 32 papers or commentaries published in Journal of Clinical Monitoring and Computing in 2016, within the field of respiration. Papers were published covering airway management, ventilation and respiratory rate monitoring, lung mechanics and gas exchange monitoring, in vitro monitoring of lung mechanics, CO₂ monitoring, and respiratory and metabolic monitoring techniques.

Linshom thermodynamic sensor is a reliable alternative to capnography for monitoring respiratory rate

Monitoring ventilation accurately is a technically challenging, yet indispensable aspect of patient care in the intra- and post-procedural settings. A new prototypical device known as the Linshom Respiratory Monitoring Device (LRMD) has been recently designed to non-invasively, inexpensively, and portably measure respiratory rate. The purpose of this study was to measure the accuracy and variability of LRMD measurements of respiratory rate relative to the measurement of capnography. In this prospective study, participants were enrolled and individually fitted with a face mask monitored by the LRMD and capnography. With a baseline oxygen flow rate and digital metronome to pace their respiratory rate, the participants were instructed to breathe at 10 breaths per minute (bpm) for 3 min, 20 bpm for 3 min, 30 bpm for 3 min, 0 bpm for 30 s, and resume regular breathing for 30 s. Both sensors were connected to a computer for continuous temperature and carbon dioxide waveform recordings. The data were then retrospectively analyzed. Twenty-six healthy volunteers, mean (range) age 27.8 (23-37) and mean (range) BMI 23.1 (18.8-29.2) kg/m² were recruited. There were 15 males (57.7%) and 11 females (42.3%). After excluding 3 subjects for technical reasons, 13,800 s of breathing and 4,140 expiratory breaths were recorded. Throughout the protocol, the average standard deviation (SD) for the LRMD and capnography was 1.11 and 1.81 bpm, respectively. The overall mean bias (±2SD) between LRMD and capnography was -0.33 (±0.1.56) bpm. At the lowest and intermediate breathing rates reflective of hypoventilation and normal ventilation, the LRMD variance was 0.55 and 1.23 respectively, compared to capnography with 5.54 and 7.47, respectively. At higher breathing rates indicative of hyperventilation, the variance of the test device was 4.52, still less than that of capnography at 5.73. This study demonstrated a promising correlation between the LRMD and capnography for use as a respiratory rate monitor. The LRMD technology may be a significant addition to monitoring vital signs because it offers a minimally intrusive opportunity to detect respiratory rate and apnea, without expensive or complex anesthetic equipment, before the need for life-saving resuscitation arises.