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Table 2 Limitations with the use of pulse pressure variation (PPV) to predict fluid responsiveness

From: Use of ‘tidal volume challenge’ to improve the reliability of pulse pressure variation

  Limitations Mechanisms for failure Type of error
1 Spontaneous breathing activity Irregular variations in intrathoracic pressure and thus the variation in stroke volume cannot correlate with preload dependency False positive
(may occasionally be false negative depending on the type of breathing)
2 Cardiac arrhythmias The variation in stroke volume is related more to the irregularity in diastole than to the heart‐lung interactions False positive
3 Mechanical ventilation using low tidal volume (<8 ml/kg) The small variations in intrathoracic pressure due to the low tidal volume are insufficient to produce significant changes in the intrathoracic pressure False negative
4 Low lung compliance The transmission of changes in alveolar pressure to the intrathoracic structures is attenuated False negative
5 Open thorax No change in intrathoracic pressure during the respiratory cycle False negative
6 Increased intra‐abdominal pressure Threshold values of PPV will be elevated False positive
7 Low HR/RR ratio < 3.6 (severe bradycardia or high frequency ventilation) If the RR is very high, the number of cardiac cycles per respiratory cycle may be too low to allow variation in stroke volume False negative
  1. HR heart rate, RR respiratory rate