From the Guidelines
Tidal percussion is not a recommended technique for detecting ascites due to its low sensitivity and specificity, and instead, shifting dullness should be used as it has 83% sensitivity and 56% specificity in detecting ascites 1. The physical examination for detecting ascites is crucial, and several techniques can be used. However, tidal percussion is not mentioned in the provided evidence as a reliable method for detecting ascites.
- The presence of a full, bulging abdomen should lead to percussion of the flanks to check for shifting dullness.
- Shifting dullness is a more reliable technique, with 83% sensitivity and 56% specificity in detecting ascites 1.
- Approximately 1500 mL of fluid must be present before flank dullness is detected, and if no flank dullness is present, the patient has less than a 10% chance of having ascites 1.
- Other techniques like the fluid wave and puddle sign are cumbersome and perform less well when compared to shifting dullness 1. The diagnosis of new-onset ascites is suspected on the basis of the history and physical examination and usually confirmed by successful abdominal paracentesis and/or ultrasound 1.
- Abdominal ultrasound may be required to determine with certainty if fluid is present, especially in obese patients where physical examination is problematic 1.
- The liver is commonly imaged to screen for hepatocellular carcinoma, portal vein thrombosis, and hepatic vein thrombosis 1.
From the Research
Significance of Tidal Percussion
- Tidal percussion is a technique used in physical examinations to evaluate the size, consistency, borders, and presence of fluid/air in the lungs and abdomen 2.
- The technique involves tapping body parts with fingers or small instruments to produce sounds that can be used to diagnose various conditions, including pulmonary injuries and diseases 2.
- Tidal percussion is significant in diagnosing potentially lethal conditions such as traumatic and tension pneumothorax 2.
Limitations and Applications
- The traditional technique of tidal percussion has limitations, including the subjectivity of the administrator and the limitations of the human ear, which can lead to low sensitivity 2.
- Automation of the method using a standardized percussion source and computerized classification of digitized signals can remove the subjective factor and other limitations, enabling rapid on-site diagnostics of pulmonary traumas 2.
- Tidal percussion can be used in conjunction with other techniques, such as auscultatory percussion, to detect lung abnormalities 3.
- The technique can also be used to measure tidal volume during non-invasive respiratory support, such as continuous-flow helmet CPAP 4.
Related Techniques and Measurements
- Auscultatory percussion is a related technique that involves tapping lightly the manubrium sterni while listening over the chest wall posteriorly with a stethoscope 3.
- Opto-electronic plethysmography (OEP) is a non-invasive technique that can be used to measure tidal volume during non-invasive respiratory support 4.
- Changes in thoracic and abdominal circumferences can be measured using a tape measure and rotary encoder band system to assess muscular recruitment patterns and breathing effort 5.