Oxygen management in mechanically ventilated patients: A multicenter prospective observational study

Closed-loop ventilation

PURPOSE OF REVIEW

The last 25 years have seen considerable development in modes of closed-loop ventilation and there are now several of them commercially available. They not only offer potential benefits for the individual patient, but may also improve the organization within the intensive care unit (ICU). Clinicians are showing both greater interest and willingness to address the issues of a caregiver shortage and overload of bedside work in the ICU. This article reviews the clinical benefits of using closed-loop ventilation modes, with a focus on control of oxygenation, lung protection, and weaning.

RECENT FINDINGS

Closed-loop ventilation modes are able to maintain important physiological variables, such as oxygen saturation measured by pulse oximetry, tidal volume (VT), driving pressure (ΔP), and mechanical power (MP), within target ranges aimed at ensuring continuous lung protection. In addition, these modes adapt the ventilator support to the patient's needs, promoting diaphragm activity and preventing over-assistance. Some studies have shown the potential of these modes to reduce the duration of both weaning and mechanical ventilation.

SUMMARY

Recent studies have primarily demonstrated the safety, efficacy, and feasibility of using closed-loop ventilation modes in the ICU and postsurgery patients. Large, multicenter randomized controlled trials are needed to assess their impact on important short- and long-term clinical outcomes, the organization of the ICU, and cost-effectiveness.

The ability of Oxygen Reserve Index® to detect hyperoxia in critically ill patients

Background

Hyperoxia is associated with increased morbidity and mortality in the intensive care unit. Classical noninvasive measurements of oxygen saturation with pulse oximeters are unable to detect hyperoxia. The Oxygen Reserve Index (ORI) is a continuous noninvasive parameter provided by a multi-wave pulse oximeter that can detect hyperoxia. Primary objective was to evaluate the diagnostic accuracy of the ORI for detecting arterial oxygen tension (PaO₂) > 100 mmHg in neurocritical care patients. Secondary objectives were to test the ability of ORI to detect PaO₂ > 120 mmHg and the ability of pulse oximetry (SpO₂) to detect PaO₂ > 100 mmHg and PaO₂ > 120 mmHg.

Methods

In this single-center study, we collected ORI and arterial blood samples every 6 h for 3 consecutive days. Diagnostic performance was estimated using the area under the receiver operating characteristic curve (AUROC).

Results

There were 696 simultaneous measurements of ORI and PaO₂ in 62 patients. Considering the repeated measurements, the correlation between ORI and PaO₂ was r = 0.13. The area under the receiver operating characteristic curve (AUROC), obtained to test the ability of ORI to detect PaO₂ > 100 mmHg, was 0.567 (95% confidence interval = 0.566–0.569) with a sensitivity of 0.233 (95%CI = 0.230–0.235) and a specificity of 0.909 (95%CI = 0.907–0.910). The AUROC value obtained to test the ability of SpO₂ to detect a PaO₂ > 100 mmHg was 0.771 (95%CI = 0.770–0.773) with a sensitivity of 0.715 (95%CI = 0.712–0.718) and a specificity of 0.700 (95%CI = 0.697–0.703). The diagnostic performance of ORI and SpO₂ for detecting PaO₂ > 120 mmHg was AUROC = 0.584 (95%CI = 0.582–0.586) and 0.764 (95%CI = 0.762–0.766), respectively. The AUROC obtained for SpO₂ was significantly higher than that for ORI (p < 0.01). Diagnostic performance was not affected by sedation, norepinephrine infusion, arterial partial pressure of carbon dioxide, hemoglobin level and perfusion index.

Conclusion

In a specific population of brain-injured patients hospitalized in a neurointensive care unit, our results suggest that the ability of ORI to diagnose hyperoxia is relatively low and that SpO₂ provides better detection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-022-01012-w.

Intensivists' response to hyperoxemia in mechanical ventilation patients: The status quo and related factors

BACKGROUND

Due to the still sparse literature in China, the investigation of hyperoxemia management is required. Thus, we aim to conduct a retrospective study to provide more information about hyperoxemia management in intensive care unit (ICU) patients.

METHODS

We retrospectively screened the medical records of adult patients (age ≥18 years) who required mechanical ventilation (MV) ≥24 hours from January 1, 2018, to December 31, 2018. All arterial blood gas (ABG) tested during MV was retrieved, and MV settings were recorded. The median arterial partial pressure of oxygen (PaO₂) >120 mmHg (1 mmHg=0.133 kPa) was defined as mild to moderate hyperoxemia, and PaO₂ >300 mmHg as extreme hyperoxemia. Intensivists' response to hyperoxemia was assessed based on the reduction of fraction of inspired oxygen (FiO₂) within one hour after hyperoxemia was recorded. Multivariable logistic regression analysis was performed to determine the independent factors associated with the intensivists' response to hyperoxemia.

RESULTS

A total of 592 patients were finally analyzed. The median Acute Physiology and Chronic Health Evaluation II (APACHE II) score was 21 (15-26). The PaO₂, arterial oxygen saturation (SaO₂), FiO₂, and positive end expiratory pressure (PEEP) were 96.4 (74.0-126.0) mmHg, 97.8% (95.2%-99.1%), 0.4 (0.4-0.5), and 5 (3-6) cmH₂O, respectively. Totally 174 (29.39%) patients had PaO₂ >120 mmHg, and 19 (3.21%) patients had extreme hyperoxemia at PaO₂ >300 mmHg. In cases of mild to moderate hyperoxemia with FiO₂ ≤0.4, only 13 (2.20%) patients had a decrease in FiO₂ within one hour. The multivariable logistic regression analysis showed that a positive response was independently associated with FiO₂ (odds ratio [OR] 1.09, 95% confidence interval [CI] 1.06-1.12, P<0.001), PaO₂ (OR 1.01, 95% CI 1.00-1.01, P=0.002), and working shifts (OR 5.09, 95% CI 1.87-13.80, P=0.001).

CONCLUSIONS

Hyperoxemia occurs frequently and is neglected in most cases, particularly when mild to moderate hyperoxemia, hyperoxemia with lower FiO₂, hyperoxemia during night and middle-night shifts, or FiO₂ less likely to be decreased. Patients may be at a risk of oxygen toxicity because of the liberal oxygen strategy. Therefore, further research is needed to improve oxygen management for patients with MV in the ICUs.

Point-of-care testing (POCT) and IT security concepts

Point-of-care testing (POCT) has been an essential service in hospitals for many years with a main focus on reliability, classical laboratory quality criteria and easy handling. Hospital information technology (IT) security regulations, however, have not yet been adapted to the specificities of POCT. Following the POCT Symposium in Munich, the “1st Round Table POCT-IT-Security Meeting” held in October 2019 in Cologne addressed these issues and managed to establish first consensus results in the essential fields of user, data and update management, as well as network connections and user-friendliness. First practical steps include optimizing the user management by connection to a directory service and definition of access control (including emergency authorization). Patient data economy on analyzers in combination with data and data transmission encryption as well as technically secure communication protocols are relevant steps in the fields of data management and network connections. An update management needs to be contractually defined for remote services and generally includes testing in a protocol-based scenario. Providing an organizational structure for POCT-IT security is a necessary prerequisite, as are continuous training and awareness for this topic with a strong focus on usability.