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KEY POINTS

  • andomized trials have found that the use of a pulmonary artery catheter did not influence the mortality of critically ill patients with shock or acute respiratory distress syndrome.

  • Randomized trials have shown that protocols based on right atrial pressure (Pra) and superior vena cava oxygenation performed no better than usual care in managing patients with septic shock.

  • Partial wedging can lead to overestimation of the pulmonary artery wedge pressure (Ppw) and should be suspected when the measured Ppw exceeds the pulmonary artery diastolic pressure (Ppad). In patients with pulmonary hypertension, partial wedging may be present despite a positive Ppad–Ppw gradient.

  • Positive end-expiratory pressure (PEEP) and active expiration cause the measured Ppw and Pra to overestimate transmural pressure, with active expiration resulting in greater errors. Simultaneous recording of bladder pressure and Pra (or Ppw) can be used to assess the impact of active expiration on transmural pressure.

  • Hemodynamic waveforms may be helpful in the diagnosis of certain cardiac disorders: Large v waves in the Ppw tracing are seen in acute mitral regurgitation but can also occur with hypervolemia. Cardiac tamponade is characterized by equalization of the Ppw and Pra with blunting of the y descent. Tricuspid regurgitation often produces a broad c-v wave and a prominent y descent. Inspection of the Pra during narrow complex tachycardias may be helpful if flutter waves or regular cannon a waves (supraventricular reentrant tachycardia) are seen.

  • Neither the Pra nor the Ppw is a reliable predictor of fluid responsiveness over the range of values most often seen in the ICU. However, the failure of the Pra to fall with spontaneous inspiration suggests that the patient is unlikely to benefit from a fluid challenge.

INTRODUCTION

For several decades, decisions regarding therapy with fluids and vasoactive drugs in the ICU relied on intravascular pressures obtained with either a central venous catheter (CVC) or pulmonary artery catheter (PAC). Despite this widespread use, the value of invasive hemodynamic monitoring has been questioned.1–4 Randomized studies of the PAC in a variety of clinical settings found neither a positive nor a negative impact on mortality.5,6 To some, this provided compelling evidence against continued use of the PAC.1,2 Others have argued that these studies established the safety of the PAC and that an impact on mortality is an unreasonable benchmark for any bedside monitoring device.7,8 Use of the CVC for hemodynamic monitoring is also controversial. Although previous guidelines for management of septic shock recommended measurement of central venous pressure (CVP) and superior vena cava oxygen saturation as components of early goal-directed therapy,9 subsequent randomized trials found that this approach yielded outcomes that were no better than usual care.10 Some have suggested that use of the CVP should be abandoned,3 while others argue that it still has value if it is not interpreted in isolation and its limitations are fully understood.11–14

The ...

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