Julian M. Goldman

Deliberate Perioperative Systems Design Improves Operating Room Throughput

Background:New operating room (OR) design focuses more on the surgical environment than on the process of care. The authors sought to improve OR throughput and reduce time per case by goal-directed design of a demonstration OR and the perioperative processes occurring within and around it. Methods:The authors constructed a three-room suite including an OR, an induction room, and an early recovery area. Traditionally sequential activities were run in parallel, and nonsurgical activities were moved from the OR to the supporting spaces. The new workflow was supported by additional anesthesia and nursing personnel. The authors used a retrospective, case- and surgeon-matched design to compare the throughput, cost, and revenue performance of the new OR to traditional ORs. Results:For surgeons performing the same case mix in both environments, the new OR processed more cases per day than traditional ORs and used less time per case. Throughput improvement came from superior nonoperative performance. Nonoperative Time was reduced from 67 min (95% confidence interval, 64–70 min) to 38 min (95% confidence interval, 35–40 min) in the new OR. All components of Nonoperative Time were meaningfully reduced. Operative Time decreased by approximately 5%. Hospital and anesthesia costs per case increased, but the increased throughput offset costs and the global net margin was unchanged. Conclusions:Deliberate OR and perioperative process redesign improved throughput. Performance improvement derived from relocating and reorganizing nonoperative activities. Better OR throughput entailed additional costs but allowed additional patients to be accommodated in the OR while generating revenue that balanced these additional costs.

Communication in critical care environments: mobile telephones improve patient care.

Most hospital policies prohibiting the use of wireless devices cite reports of disruption of medical equipment by cellular telephones. There have been no studies to determine whether mobile telephones may have a beneficial impact on safety. At the 2003 meeting of the American Society of Anesthesiologists 7878 surveys were distributed to attendees. The five-question survey polled anesthesiologists regarding modes of communication used in the operating room/intensive care unit and experience with communications delays and medical errors. Survey reliability was verified using test-retest analysis and proportion agreement in a convenience sample of 17 anesthesiologists. Four-thousand-eighteen responses were received. The test-retest reliability of the survey instrument was excellent (Kappa = 0.75; 95% confidence interval, 0.56–0.94). Sixty-five percent of surveyed anesthesiologists reported using pagers as their primary mode of communications, whereas only 17% used cellular telephones. Forty-five percent of respondents who use pagers reported delays in communications compared with 31% of cellular telephone users. Cellular telephone use by anesthesiologists is associated with a reduction in the risk of medical error or injury resulting from communication delay (relative risk = 0.78; 95% confidence interval, 0.6234–0.9649). The small risks of electromagnetic interference between mobile telephones and medical devices should be weighed against the potential benefits of improved communication.

Toward patient safety in closed-loop medical device systems

A model-driven design and validation of closed-loop medical device systems is presented. Currently, few if any medical systems on the market support closed-loop control of interconnected medical devices, and mechanisms for regulatory approval of such systems are lacking. We present a system implementing a clinical scenario where closed-loop control may reduce the possibility of human error and improve safety of the patient. The safety of the system is studied with a simple controller proposed in the literature. We demonstrate that, under certain failure conditions, safety of the patient is not guaranteed. Finally, a more complex controller is described and ensures safety even when failures are possible. This investigation is an early attempt to introduce automatic control in clinical scenarios and to delineate a methodology to validate such patient-in-the-loop systems for safe and correct operation.

Model-Driven Safety Analysis of Closed-Loop Medical Systems

In modern hospitals, patients are treated using a wide array of medical devices that are increasingly interacting with each other over the network, thus offering a perfect example of a cyber-physical system. We study the safety of a medical device system for the physiologic closed-loop control of drug infusion. The main contribution of the paper is the verification approach for the safety properties of closed-loop medical device systems. We demonstrate, using a case study, that the approach can be applied to a system of clinical importance. Our method combines simulation-based analysis of a detailed model of the system that contains continuous patient dynamics with model checking of a more abstract timed automata model. We show that the relationship between the two models preserves the crucial aspect of the timing behavior that ensures the conservativeness of the safety analysis. We also describe system design that can provide open-loop safety under network failure.

Plug-and-Play for Medical Devices: Experiences from a Case Study

Medical devices are pervasive throughout modern healthcare, but each device works on its own and in isolation. Interoperable medical devices would lead to clear benefits for the care provider and the patient, such as more accurate assessment of the patient’s health and safety interlocks that would enable error-resilient systems. The Center for Integration of Medicine & Innovative Technology (www.CIMIT.org) sponsors the Medical Device Plug-and-Play Interoperability program (www.MDPnP.org), which is leading the development and adoption of standards for medical device interoperability. Such interoperable medical devices will lead to increased patient safety and enable new treatment options, and the aim of this project is to show the benefits of interoperable and interconnected medical devices.

Low-dose intrathecal morphine for postoperative pain control in patients undergoing transurethral resection of the prostate.

Thirty patients undergoing lidocaine spinal anesthesia for transurethral resection of the prostate (TURP) were studied to evaluate the effectiveness of low-dose intrathecal morphine (ITM) for postoperative analgesia. In a double-blinded fashion, groups of ten patients received either 0.1 mg morphine, 0.2 mg morphine, or placebo (control group) intrathecally with lidocaine 75 mg. Standard postoperative analgesics were available to all patients. Patients receiving 0.1 mg or 0.2 mg morphine reported significantly less postoperative pain as assessed by an inverse numerical visual pain scale and required significantly fewer postoperative analgesic interventions than the control group. There was no difference between the 0.1 mg ITM and 0.2 mg ITM groups with regard to severity of postoperative pain or analgesic requirements. The incidence of nausea and vomiting was significantly higher in the group receiving 0.2 mg ITM than in the control group. Six patients (60%) in the 0.2 mg ITM group, two patients (20%) in the 0.1 mg ITM group, and one patient (10%) in the control group experienced nausea and vomiting. No clinically evident respiratory depression occurred in any of the subjects. The authors conclude that administration of 0.1 mg or 0.2 mg of morphine intrathecally is effective in reducing postoperative pain following TURP and that 0.1 mg ITM is not associated with nausea and vomiting.

OpenICE: An Open, Interoperable Platform for Medical Cyber-Physical Systems

Medical devices in hospitals and other clinical settings are not yet networked with each other. This leads to compartmentalization and siloing of information, false positive alarms where stand-alone devices are not aware of the patients context, and worsened patient outcomes when novel, life-saving algorithms cannot even be prototyped. In response to this situation, we have developed an open source implementation of the Integrated Clinical Environment (ICE) standard ASTM 2761-09(2013). The platform consists of software device adapters for medical devices (including anesthesia machines, ventilators, and patient monitors), OMG DDS standard middleware, and demonstration applications. Applications can be built on this platform to implement smart alarms, physiologic closed-loop control algorithms, data visualization, and clinical research data collection. The ICE standard defines an architecture for building a safe patient-centric Integrated Clinical Environment. It defines roles for device adapters, a network controller that mediates traffic, a supervisor capable of hosting applications, a data logger for forensic analysis, and external interfaces to hospital resources such as an EHR, ADT, or pharmacy system. Over the last 8 years, working with a broad team of collaborators, we have built numerous prototype medical distributed systems. These have ranged from a deterministic, hard real-time network implemented on custom FPGA hardware to approaches built on web services. There exist many different middlewares, and our requirements allow us to choose an appropriate one. An ideal middleware would support an abstract API that would permit many instantiations on varying hardware and software platforms. Safe interoperability requires that participants on the network all play by the same rules. DDS was chosen as the middleware for this prototype because it supports the expression of a wide range of quality of service parameters, allowing us to support a variety of clinical scenarios suggested by our user community. Data published by apps can be indistinguishable from that provided by physical medical devices, enabling sophisticated data processing apps that may generate data for use by other system components. Matching publishers to subscribers requires that all of the participants use a common set of terms. For this work, a subset of the ISO/IEEE 11073-10101 nomenclature was used. This allows for components (applications or devices) to be interoperable. Using this approach, device manufacturers will be able to produce devices with electronic interfaces that will work with any ICE application, and any ICE application will work with any device that provides the necessary data elements. We are presenting an initial implementation here in anticipation of useful feedback from the CPS community furthering future versions that will be suitable for mainstream clinical use. Updates will be available to the community at mdpnp.sourceforge.net, and we are working on an ICE Application exchange (ICE AX) site where clinical researchers can post and download ICE applications.

Smart checklists for human-intensive medical systems

Human-intensive cyber-physical systems involve software applications and hardware devices, but also depend upon the expertise of human participants to achieve their goal. In this paper. we describe a project we have started to improve the effectiveness of such systems by providing Smart Checklists to support and guide human participants in carrying out their tasks, including their interactions with the devices and software applications.

A Treatment Validation Protocol for Cyber-Physical-Human Medical Systems

In cyber-physical-human medical environments, coordinating supervisory medical systems and medical staff to perform treatments in in accordance with best practice is essential for patient safety. However, the dynamics of patient conditions and the non-deterministic nature of potential side effects of treatments pose significant challenges. In this paper, we propose a validation protocol to enforce the correct execution sequence of performing treatment, regarding preconditions validation, side effects monitoring, and expected responses checking based on the path physiological models. The proposed protocol organizes the medical information concisely and comprehensively to help medical staff validate treatments. Unlike traditional validation mechanism for cyber systems, the medical system cannot lock or rollback the states of physical components, such as patient conditions. Therefore, the proposed protocol dynamically adapts to the patient conditions and side effects of treatments. Moreover, a cardiac arrest scenario is used as a case study to verify the safety and correctness properties of the proposed protocol.

A low complexity coordination architecture for networked supervisory medical systems

Cooperating medical devices, envisioned by Integrated Clinical Environment (ICE) of Medical Device Plug-and-Play (MDPnP), is expected to improve the safety and the quality of patient care. To ensure safety, the cooperating medical devices must be thoroughly verified and tested. However, concurrent control of devices without proper coordination poses a significant challenge for the verification of the safety, since complex interaction patterns between devices might cause the explosion of the verification state space. In this paper, we propose a low-complexity coordination architecture and protocol for networked supervisory medical systems. The proposed architecture organizes the systems in a hierarchical and organ-based manner in accordance to human physiology and home-ostasis. Further, the proposed protocol avoids potential conflicts and unsafe controls, while allowing efficient concurrent operations of medical devices. The evaluation results show that our approach reduce the complexity by several orders of magnitude.