Decision Support for Intraoperative Low Blood Pressure
Condition: Hypotension
MeSH terms: Hypotension
Study type: Interventional

Summary: 
      The purpose of this study is to determine whether a decision support system can improve the
      adherence to thresholds for low blood pressure by anesthesia providers, which in turn
      prevents their patients from having organ injury.
    

Detailed description: 
      Blood pressure management is an important part of anesthesia. Many factors contribute to a
      change in blood pressure during a surgical procedure, such as blood loss, manipulation by
      surgeons, and there are several mechanisms through which anesthesia itself changes blood
      pressure. Although a high blood pressure also occurs during anesthesia, most of these factors
      lower a patient's blood pressure. When a patient's blood pressure becomes too low, the
      internal organs become at risk of receiving not enough blood (low perfusion or
      hypoperfusion). This low perfusion state can result in organ damage (ischemia) because of an
      insufficient supply of oxygen and glucose. Hence the important task of anesthesia providers
      to maintain the blood pressure of patients, using a wide range of drugs and other
      interventions.

      A big challenge in blood pressure management is to know when a low blood pressure indeed
      results in low perfusion of organs. There is a large variation between patients in how
      susceptible they are to low blood pressure, as well as a difference between the organs in how
      easily they are damaged because of low perfusion. Elder patients, or patients with
      preexisting hypertension, heart problems or other cardiovascular diseases are more prone to a
      low blood pressure and are more likely to develop organ ischemia when there is a low blood
      pressure. The kidneys, the heart and the brain are the organs that are most at risk of organ
      damage. As one cannot measure the perfusion states of individual organs in individual
      patients, it is very difficult to know 'how low to go' with a patient's blood pressure.

      Recent studies have used large datasets of patients to demonstrate that there is statistical
      association between low blood pressure during surgery and various types of organ injury. As
      patients are already treated for low blood pressure by anesthesia providers, this suggests
      that patients have low organ perfusion states despite the current treatment standards. A
      patient's blood pressure is not simply a dial that can be adjusted to a specific level.
      Finding the right level of interventions can be difficult in some patients. Consequently,
      lower blood pressures are common in anesthesia, even with the current standards of blood
      pressure management.

      In this proposed study the investigators will implement two forms of decision support to
      assist anesthesia providers in blood pressure management. The decision support aims to
      educate anesthesia providers about the risks of low blood pressures in direct relation to the
      patients that they treat. One form of decision support will provide automated notifications
      through pagers and through the anesthesia information management system. These automated
      notifications pop up when the patient's blood pressure drops below a level that is associated
      with a risk of organ injury, and thus alerts the anesthesia provider of the blood pressure
      and its associated risk. The second form of decision support will send a postoperative email
      the day after the procedure when the patient has had a low blood pressure for particular
      duration. This email then provides feedback to the anesthesia provider by informing them of
      the increased risks of organ injury that are associated with that low blood pressure.

      The study will look at both a change in patient outcome and a change in blood pressure
      management and will be performed at the Vanderbilt University Medical Center (VUMC). The
      change in patient outcome will primarily be studied through the occurrence of acute kidney
      injury in the first days following the procedure at the VUMC. The change in blood pressure
      management (provider behavior) will be studied by observing the depth and duration of low
      pressures during anesthesia, and the number of interventions that have been used to treat the
      blood pressure. Patient outcome will be studied by comparison of a baseline phase - before
      the decision support is implemented and uses historic data- and the intervention phase - the
      period during which the intervention is active. Only routinely collected clinical data will
      be used for these analyses: no additional data collection is required.

      As it is impossible to know which form of decision support will be the most effective, the
      first three months of the intervention period will be a 'nested cluster-randomized trial'.
      The anesthesia providers (not the patients) will be randomized to either the automated
      notifications or the feedback emails. After three months all anesthesia providers will
      receive both forms of decision support for the remainder of the intervention period. The
      reason why anesthesia providers are randomized only during the first three months is that
      cross-over or contamination between the two groups is expected. This contamination could make
      it impossible to study the effect of the decision support on patient outcome, as there will
      be no longer any difference between the study groups.
    

Intervention name(s): Attending real-time decision support; In-room real-time decision support; Attending feedback emails; In-room provider feedback emails; Anesthesia Information Management System (AIMS); Perioperative Data Warehouse (PDW); General anesthesia; Pager system; Central neuraxial anesthesia; Non-cardiac surgery; Propofol; Sevoflurane; Desflurane; Isoflurane; Ephedrine; Phenylephrine; Norepinephrine; Epinephrine; Dobutamine; Dopamine; Isoproterenol; Milrinone; Atropine; Glycopyrrolate; Vasopressin; Terlipressin; Sodium Chloride 0.9%; Ringer's lactate; Hydroxyethyl starch solutions; Fresh Frozen Plasma; Packed Red Blood Cells; Albumin solutions; Plasma-Lyte; Lidocaine; Bupivacaine; Levobupivacaine; Ropivacaine; Mepivacaine; Tetracaine; Prilocaine; Procaine; Chloroprocaine; Benzocaine; Articaine
Intervention type(s): Procedure; Procedure; Procedure; Procedure; Device; Device; Procedure; Device; Procedure; Procedure; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug; Drug
Intervention description(s): Near real-time decision support elements will notify the attending anesthesiologists of a blood pressure drop below the threshold for intraoperative hypotension (mean arterial pressure below 60 mmHg). The notification is presented through the pager system. The page will also display the associated increased risk of organ injury due to organ ischemia.; Near real-time decision support elements will notify the in-room anesthesia provider of a blood pressure drop below the threshold for intraoperative hypotension (mean arterial pressure below 60 mmHg). The notification is presented through the anesthesia information management system. The decision support system will display the associated increased risk of organ injury due to organ ischemia.; Attending anesthesiologists will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension (mean arterial pressure below 60 mmHg or lower for a particular duration) that is associated with an increased risk of organ injury due to organ ischemia.; In-room anesthesia providers will be notified through email within 24 hours after the end of an anesthetic case, when the patient had an episode of intraoperative hypotension (mean arterial pressure below 60 mmHg or lower for a particular duration) that is associated with an increased risk of organ injury due to organ ischemia.; The anesthesia electronic record keeping system; The data warehouse that is used to gather perioperative data and create user reports. In this instance the PDW will be used to send the postoperative feedback emails.; Any anesthetic drugs that are used to induce general anesthesia above the level of sedation.; The mobile pager system through which alerts can be sent; Regional anesthesia effectuated through the placement of local anesthetics around the nerves of the central nervous system, e.g. spinal anesthesia and epidural anesthesia.; Any surgical intervention that is not aimed at surgical correction of the heart; Anesthetic drug used to maintain general anesthesia; Anesthetic drug used to maintain general anesthesia; Anesthetic drug used to maintain general anesthesia; Anesthetic drug used to maintain general anesthesia; Cardiovascular drug used to treat intraoperative hypotension; Cardiovascular drug used to treat intraoperative hypotension; Cardiovascular drug used to treat intraoperative hypotension; Cardiovascular drug used to treat intraoperative hypotension; Cardiovascular drug used to treat intraoperative hypotension; Cardiovascular drug used to treat intraoperative hypotension; Cardiovascular drug used to treat intraoperative hypotension; Cardiovascular drug used to treat intraoperative hypotension; Cardiovascular drugs used to treat intraoperative hypotension; Cardiovascular drug used to treat intraoperative hypotension; Cardiovascular drug used to treat intraoperative hypotension; Cardiovascular drug used to treat intraoperative hypotension; Intravenous fluid used to treat intraoperative hypotension; Intravenous fluid used to treat intraoperative hypotension; Intravenous fluid used to treat intraoperative hypotension; Intravenous fluid used to treat intraoperative hypotension; Intravenous fluid used to treat intraoperative hypotension; Intravenous fluid used to treat intraoperative hypotension; Intravenous fluid used to treat intraoperative hypotension; Local anesthetic used for central neuraxial anesthesia.; Local anesthetic used for central neuraxial anesthesia.; Local anesthetic used for central neuraxial anesthesia.; Local anesthetic used for central neuraxial anesthesia.; Local anesthetic used for central neuraxial anesthesia.; Local anesthetic used for central neuraxial anesthesia.; Local anesthetic used for central neuraxial anesthesia.; Local anesthetic used for central neuraxial anesthesia.; Local anesthetic used for central neuraxial anesthesia.; Local anesthetic used for central neuraxial anesthesia.; Local anesthetic used for central neuraxial anesthesia.
Other intervention name(s): Regional anesthesia; Spinal anesthesia; Intrathecal anesthesia; Subarachnoid anesthesia; Epidural anesthesia; Central neuraxial blockade; Lignocaine
Intervention MeSH terms: Lidocaine; Atropine; Terlipressin; Phenylephrine; Dobutamine; Dopamine; Milrinone; Isoproterenol; Vasopressins; Epinephrine; Norepinephrine; Ephedrine; Glycopyrrolate; Bupivacaine; Ropivacaine; Levobupivacaine; Tetracaine; Prilocaine; Mepivacaine; Benzocaine; Chloroprocaine; Procaine; Anesthetics; Propofol; Sevoflurane; Desflurane; Isoflurane; Pharmaceutical Solutions; Plasma-lyte 148
Allocation: Non-Randomized
Intervention model: Sequential Assignment
Intervention model description: It is an interrupted time-series of a decision support package intervention that aims to study the the effect of the decision support package on patient outcome. The effects of the individual decision support components of the package on healthcare provider behavior will be studied in a nested cluster-randomized trial: in the first month the attending anesthesiologists will be randomized to near-realtime notifications or feedback emails; in the second month in-room providers will be randomized to near-realtime notifications or feedback emails. Starting month four all providers will receive both near-realtime notifications and feedback emails.
Masking: None (Open Label)
Primary purpose: Prevention
Keywords: Decision support; Decision Support Systems, Clinical; Decision Support Techniques; Hypotension; Intraoperative Hypotension; Acute Kidney Injury; Postoperative Mortality; Blood Pressure