The Value of Peripheral Arterial Resistive Index in Evaluation of Tissue Perfusion in Patients With Septic Shock
Condition: Shock, Septic
MeSH terms: Shock, Septic; Shock
Study type: Observational

Summary: 
      In patients with septic shock, routine arterial blood pressure and central venous pressure
      are monitored in ICU. Conventional methods such as blood pressure and central venous pressure
      in septic patients cannot provide sufficient information in the follow-up due to the body's
      compensation mechanisms. The systemic vascular resistance index, which can be measured
      invasively or non-invasively with advanced hemodynamic monitoring methods, is a parameter
      that plays an important role in the management of septic patients.

      Resistive index (Pourcelot Index) is an ultrasonic measurement method used to evaluate tissue
      perfusion and microcirculation. Since peripheral tissue perfusion is impaired in septic
      patients, the investigators think resistive index may be useful for management of sepsis.
      There are studies in the literature on the use of resistive index in the follow-up of
      patients.

      The study will be about whether there is a correlation between the systemic vascular
      resistance index measured by cardiac output measurement, which is one of the advanced
      monitoring methods routinely used in the group requiring mechanical ventilation support in
      patients with septic shock, and the peripheral arterial resistive index, which is routinely
      used to evaluate tissue perfusion and microcirculation.
    

Detailed description: 
      Sepsis is not a specific disease but abnormal response for infection, leading to organ
      dysfunction. It is a clinical syndrome consisting of biological, biochemical, and
      physiological abnormalities which pathophysiology has not yet been fully determined. Sepsis
      is shaped by pathogenic factors and host factors (eg, gender, race and other genetic
      determinants, age, comorbidities, environment) and its features evolve over time. What
      distinguishes sepsis from infection is the presence of abnormal and/or irregular host
      response and organ dysfunction. It is one of the leading health problems worldwide and one of
      the leading causes of mortality in hospitalizations. Its estimated that there were 48.9
      million cases and 11 million sepsis-related deaths worldwide in 2017, accounting for almost
      20% of all global deaths. In an epidemiological study conducted in European intensive care
      units (ICU), the incidence of sepsis was reported as 38%. Pneumonia, urinary tract, and
      intra-abdominal infections account for more than 65% of all sepsis cases. According to the
      Surviving Sepsis Campaign (SSC) data, mortality rates in sepsis are 41% in Europe and 28.3%
      in the United States (USA). In a multicenter study involving 101,064 critically ill patients
      in Australia and New Zealand between 2002 and 2012, mortality rates due to sepsis were found
      to decrease over the years and finally to 18-20%. Recognition of sepsis, which can be very
      mortal, especially if not recognized fast and treatment not started, requires urgent
      attention.

      Due to the lack of treatment options targeting microcirculatory and mitochondrial
      dysfunction, treatment has been focused on correcting the macrocirculatory dysfunction in
      addition to treating the underlying cause during septic shock. In the early phase of septic
      shock, external losses and hypovolemia are seen because of capillary leakage. Therefore,
      fluid resuscitation is often recommended to increase cardiac output and improve tissue
      perfusion. However, large boluses of fluids (>30 ml/kg) do not reliably increase blood
      pressure, urine output, and end-organ perfusion, and may lead to iatrogenic damage. Sepsis is
      characterized by disruptions in tissue perfusion and abnormal peripheral vascular resistance,
      because of disruptions in microcirculation. therefore, improving vascular function and organ
      damage is crucial in the management of septic shock. For treatment of hypotension; the need
      for fluid should be determined and the right amount of fluid resuscitation should be provided
      to the right patient.

      Systemic vascular resistance is a parameter that depends on the afterload of the heart and
      corresponds to the resistance of the heart while it is working. It is the resistance the
      heart has to overcome to pump blood to the rest of the body except the lungs. The systemic
      vascular resistance index (SVRI) is defined as the ratio of mean arterial pressure (MAP) and
      central venous pressure (CVP) to cardiac index (CI) (SVRI= 80 x (MAP-CVP) / CI). In general,
      SVRI is proportional to MAP. It decreases due to vasodilation in septic patients. Compared to
      previous studies, lower SVRI in septic shock was associated with adverse outcomes and
      increased mortality. Invasive methods such as pulmonary artery catheters or relatively
      expensive methods such as PICCO are required for SVRI measurement.

      Can a more cost-effective and rapid alternative to the systemic vascular resistance index
      measured by expensive or high-risk methods be found? Ultrasound, as modern stethoscope, is a
      need especially in every 3 level ICU.

      The resistive index (RI) (Pourcelot index) is a noninvasive measurement used to evaluate
      vessel compliance with Doppler ultrasound. It is determined by a formula calculated between
      the systolic peak flow rate (PSV) and the end-diastolic flow rate (EDV) ((PSV-EDV)/PSV).
      Today RI is using for measure to assess tissue perfusion, particularly on the kidney. Renal
      RI shows changes in renal intravascular volume and hemodynamics. An inverse relationship has
      been shown between renal RI and MAP in acute kidney injury. Measurement of RI on the
      peripheral artery correlated with SVRI in a study of patients who had undergone cardiac
      surgery.

      In this study the investigators will compare RI on radial artery in wrist snuffbox (SBRI)
      with SVRI for primary outcome. Also compare SBRI with MAP, CVP, diastolic shock index, pleth
      variability index, delta stroke volume index, central venous oxygen saturation (ScvO2) and
      partial carbon dioxide gap (Pv-aCO2) for secondary outcome.

      Each patient will be followed for sepsis and septic shock. In the investigators ICU all
      sepsis patients has invasive artery canula for real-time monitoring and central venous
      catheter for blood sampling and need of vasopressor so there won't be any extra risk for this
      study. If a septic shock patient needs to mechanically ventilated and meets inclusion
      criteria, the investigators will carry out measurements just after intubation. Or, a
      mechanical ventilated patient who has developed septic shock; if patient has no spontaneous
      breathing effort, the investigators will carry out measurements. Also, arterial and central
      venous blood samples are taken after intubation or septic shock for every 6 hours, daily
      complete blood count (CBC), C-reactive protein, renal and hepatic blood analysis, and 2 times
      per week procalcitonin levels as routine at the hospital where the study is taking place in
      ICU.

      Demographic parameters, physical examination notes (capillary refill time, mottling score,
      urine output, skin turgor), systolic, diastolic and mean arterial pressure, central venous
      pressure, arterial and central venous blood gas analysis, CBC and biochemistry blood
      analysis, Acute Physiology and Chronic Health Evaluation II (APACHE II) score, Sequential
      Organ Failure Assesment (SOFA) score and Nutrition Risk in the Critically Ill (NUTRIC) Score
      will be noted. For cardiac output monitoring Baxter Starling non-invasive monitor will be
      used and all hemodynamic parameters will be noted for study during examination.. For
      measuring SBRI Philips CX50 ultrasound device L12-3 linear probe will be used. Starling
      monitors 4 electrodes will be placed as specified by the manufacturer. Masimo Rad-87 probe
      will place hand index or middle finger. SBRI will measure for three times successive with 1.5
      centimeters depth and 3 same measurement will be recorded. At the same time baseline
      evaluation will be started with Starling monitor and all parameters will be noted. After
      completion of baseline measurement Starling fluid challenge will be initiated as passive leg
      raising as specified by manufacturer. This procedure takes 3 minutes to calculate and after
      2.5 minutes SBRI will be measured again as described above. At the end of fluid challenge all
      parameters will be noted.
    

Intervention name(s): hemodynamic monitoring; resistive index; Pleth variability index
Intervention type(s): Diagnostic Test; Diagnostic Test; Diagnostic Test
Intervention description(s): Baxter Starling Monitor for measuring cardiac output and systemic vascular resistance (SVRI) which is using bioreactance technology. We need to place four electrodes on chest wall (upper left, upper right, down left, down right) and input monitor demographic parameters. Also enter mean arterial pressure (MAP) for calculating SVRI so we input MAP every minute.Patient bed set as 45 degree head elevated and legs 0 degree. Just after start measuring, monitor needs to synchronize itself for patient. After synchronisation we start fluid challenge with passive leg raising option. This test has two stages. First stage calculating baseline parameters which takes 3 minutes and second stage is measuring difference with fluid challenge which also takes 3 minutes. At the end of first stage monitor shows to perform passive leg raise and we perform trendelenburg maneuver till head comes to 0 degree. After second stage measurement has finished.; We use ultrasonography at the same time with cardiac output monitor in both stages. First we determine the location of radial artery at wrist snuffbox at 1.5 centimeters depth with linear probe and confirm pulsatile flow with color mode. In Starling's baseline stage we measure and calculate resistive index with doppler P-mode in triplex setting 3 times. When received 3 same result successively we noted as SBRI-1. Second measurement is initiated at last 30 seconds of passive leg raising as described before and we noted our measurement as SBRI-2; During all stages Masimo Rad-87 rainbow probe is placed patients index or middle finger and we note PVI-1 and PVI-2 at the same time with SBRI-1 and SBRI-2
Other intervention name(s): Non Invasive Cardiac Output Monitor (NICOM); SBRI; Snuffbox resistive index; Pourcelot index; doppler ultrasonography; PVI; Rad-87
Observational model: Case-Only
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Patients who admited to intensive care unit of Bezmialem Vakıf Univesity Hospital
      
Keywords: Septic shock; SBRI; SVRI; systemic vascular resistance index; resistive index; Pourcelot index