Diaphragm ultrasound as a predictor of patients at risk of pulmonary postoperative complications after phrenic nerve compromise.
L. Rovira Soriano, P. Kot, I. Leon, J. Hernandez, S. Pozo , J. De Andres
1Hospital General Universitario de Valencia - Valencia (Spain)

Background and Goal of Study:In some patient, procedures(anesthetic or surgical) that could produce phrenic nerve palsy should be avoided because it produces ipsilateral hemidiaphragm palsy, this significantly reduces FVC and FEV1 by 30%.Currently, the use of diaphragmatic ultrasound applied during
weaning in critical care patients has shown that after unilateral phrenic nerve injury, extubation was possible when there was a contralateral health hemidiaphragm with at least diaphragmatic thickening Fraction (DTF)>30%(1) and diaphragmatic excursion (DE)>25mm. Diaphragm evaluation using DTF and DE during the perioperative period can be useful in detecting patients at risk of suffering postoperative pulmonary complications(PPC) if hemidiaphragm palsy occurs.
Materials and Methods: We conducted an observational study in 6 patients with ipsilateral hemidiaphragm palsy due to interscalenic block(ISB) for shoulder surgery at post-anesthesia care unit (PACU). In all the patients DTF and DE were obtained pre and postoperative. DTF was calculated measuring diaphragm thick at TLC and FRC in aposition zone(5-8th intercostal space at axillary line) with a linear 12Mhz probe. DE measures diaphragm movement with a convex 3-5 Mhz probe at subcostal space; we recorded SaO2/FiO2,
FR, and PPC at PACU.
Results and Discussion: The echographic evaluation of the diaphragm lasted 8±3 minutes. 83% of patients (5/6) has postoperative complete palsy of ipsilateral hemidiaphragm after ISB. But only 16% of patients (1/6) has postoperative pulmonary complications. Patient ID2 has Dyspnoea, tachypnoea of 34 rpm, and SaO2/FiO2 reduction from 466 to 247 at PACU. Diaphragm evaluation of ID2 shows DTF=28% and DE=14mm. In this small case report series study, patients with ipsilateral hemidiaphragm palsy after ISB
were common, this fact didn´t produce PPC because contralateral healthy hemidiaphragm has DTF>30% and DE>25mm. the only patient with PPC has DTF<30% and E<25mm. This cut point is only validated for weaning not for PPC prediction, a new study is granted to validate this test because this evaluation could increase patient safety.

Conclusions: When phrenic palsy could be produced, perioperative Point-of-Care Ultrasound measuring DTF and DE of contralateral healthy hemidiaphragm seem a fast and simple test to detect and prevent complications.

References: DiNino E, et al. Diaphragm ultrasound as a predictor of successful extubation from mechanical ventilation.Thorax.2014 May;69(5):423-7

09 / Diaphragm ultrasound as a predictor of patients at risk of pulmonary postoperative complications after phrenic nerve compromise.