Diaphragm Ultrasound in Cardiac Surgery: State of the Art

Ultrasound analysis of hemidiaphragm function in case of pleural effusion

Background

Diaphragm dysfunction is frequently observed in patients with pleural effusion. The aim of the study was to determine the criteria for estimating the impact of pleural fluid on diaphragm function and detecting impairment of diaphragmatic muscle.

Methods

This was a retrospective observational study carried out in a university hospital. Cases of free pleural effusion were recruited from the ultrasound consultation of the lung function test laboratory. The quantification of pleural effusion and analysis of diaphragmatic function were performed using chest ultrasound performed while sitting. In case of abnormal diaphragmatic motion, the examination was repeated in supine position.

Results

109 pleural effusions (57 left, 52 right) were included in the analysis. Pleural effusions were detected after thoracic surgery in 89% of cases and in the context of medical disease in other cases. Excursion during deep inspiration was reduced by the amount of fluid (4.3 ± 2.1 cm for small effusions, 3.2 ± 1.7 cm for moderate effusions and 1.1 ± 1.8 cm for large effusions). In 23 cases of large pleural effusion, the excursions during deep inspiration were always below the lower limit of normal. In some cases, a paradoxical motion suggesting hemidiaphragm paralysis was observed. When the inspiratory thickening was normal, the paradoxical excursions disappeared in supine position. In moderate pleural effusion (53 cases), hemidiaphragm excursion was above lower limit of normal in 68% of cases. In cases of paradoxical motions, repeated ultrasound examinations were in favor of hemidiaphragm paralysis. In small pleural effusion (32 cases) the excursion was most often normal.

Conclusion

The ultrasound analysis of diaphragm excursion and thickening in sitting and supine positions is useful to assess the impact of pleural effusion and detect impairment in diaphragm muscle function.

Diaphragmatic and pericardial reconstruction using a Gore-Tex® patch in a patient with an invasive liver malignancy

The Gore-Tex® polytetrafluoroethylene patch is one of the most used prostheses for diaphragm, vessel, and pericardial reconstruction. It is strong, flexible, and relatively inexpensive and can be fitted to match the size of the resected area. In addition, it can be used to reconstruct the pericardium and diaphragm following resection to treat diffuse malignant pleural mesothelioma or repair large hiatal hernias. However, the use of polytetrafluoroethylene for hepatocellular carcinoma with diaphragmatic and pericardial invasion has not yet been reported. We report the case of a 72-year-old man with hepatocellular carcinoma with diaphragmatic and pericardial invasion. Subsequently, laparotomic liver subsegmentectomy of segment 3 and resection of the diaphragm and pericardium were performed. The defects were successfully reconstructed using the polytetrafluoroethylene patch, without postoperative complications. This is the first report describing a case of invasive liver malignancy that required simultaneous diaphragmatic and pericardial reconstruction using a polytetrafluoroethylene patch, indicating that the polytetrafluoroethylene patch could effectively and directly treat invasive liver malignancies.

Risk Factors and Predictors of Prolonged Mechanical Ventilation Following Cardiac Surgery: A Narrative Review

The subset of patients requiring prolonged mechanical ventilation is significantly high worldwide, making it an important topic of continuous and ongoing research. Over the years, various articles have shown that there may be predictors of prolonged ventilation that could be applied in healthcare to make it more patient-centered. The available literature suggests that authors have different definitions of "prolonged" ventilation. However, most critical care units embrace caution if a patient needs mechanical ventilation for more than 48 to 72 hours. The major benefits of mechanical ventilation are an overall decrease in the work of breathing and the facilitation of relatively easier pumping from an ailing heart. An elevated risk of prolonged ventilation after cardiac surgery exists in patients with higher classes of heart failure (as classified by the New York Heart Association (NYHA) or Canadian Cardiovascular Society (CCS)), a pre-existing congenital or acquired cardiac abnormality, and patients with renal failure, to name a few. The impact on quality of life has also been widely studied; as mortality rates increase with factors like age and days dependent on ventilation. Patients undergoing prolonged ventilation constitute an administrative challenge for critical care units, highlighting how multiple patients in this bracket can overwhelm the healthcare system. The use of prediction models in this context can aid healthcare delivery tremendously. Using different predictors, we can craft tailor-made treatment options and achieve the goal of more ventilator-free days per patient.

Post-Myocardial Infarction Rehabilitation: The Absence in the Rehabilitation Process of the Diaphragm Muscle

Myocardial infarction (MI) is one of the leading causes of death worldwide. There can be many reasons that cause MI, such as a sedentary lifestyle, a disordered diet, harmful habits such as smoking and alcoholism, concomitant congenital or acquired systemic pathologies. Patients who survive the acute event suffer a functional alteration of multiple body systems. The various cardiology associations recommend starting a rehabilitation process, pursuing the main objective of improving the patient's health status. A negative consequence that can be linked to MI is the dysfunction of the main breathing muscle, the diaphragm. The diaphragm is essential not only for respiratory mechanisms but also for adequate production of cardiac pressures. Post-MI patients present a reduction in the performance of the diaphragm muscle, and this condition can become a risk factor for further relapses or for the onset of heart failure. The article reviews the rehabilitation path for post-MI patients, to highlight the absence given to the diaphragm in the recovery of the patient's health status. The text reviews the post-MI diaphragmatic adaptation to highlight the importance of including targeted training for the diaphragm muscle in the rehabilitation process.

Diaphragmatic elevations following cardiac surgery

Background

This study aims to investigate the incidence, prognosis, and etiology of diaphragmatic elevation following cardiac surgery.

Methods

Between February 2019 and December 2019, a total of 888 patients (631 males, 257 females; mean age: 58.4±12.1 years; range, 19 to 84 years) who underwent cardiac surgery were retrospectively analyzed. A series of chest X-rays taken before and after surgery were analyzed to detect diaphragmatic elevation. The patients were divided into two groups: those without diaphragmatic elevation (Group 1, n=789) and those with diaphragmatic elevation (Group 2, n=99).

Results

Diaphragmatic elevation occurred in 11.14% of patients. Of these patients, 85% recovered within a year. Patients with concomitant chronic obstructive pulmonary disease and diaphragmatic elevation exhibited prolonged mechanical ventilation compared to chronic obstructive pulmonary disease patients without elevation. The incidence of diaphragmatic elevation was higher in coronary artery bypass grafting patients compared to others (p<0.001). A secondary analysis utilizing propensity score matching revealed topical cold slush as an independent risk factor for diaphragmatic elevation. Incidence and hospitalization duration were higher among patients exposed to topical cold slush (p=0.011 and p=0.002, respectively). Left internal mammary artery harvesting and diabetes mellitus were associated with increased incidence of diaphragmatic elevation.

Conclusion

Diaphragmatic elevation is frequent following cardiac surgery, particularly in coronary artery bypass grafting patients with diabetes mellitus. Among chronic obstructive pulmonary disease patients, diaphragmatic elevation can lead to unfavorable clinical outcomes. Minimizing the use of topical cold slush and considering beating heart surgery may be prudent in high-risk groups to reduce diaphragmatic elevation incidence.

Symptoms Arising From the Diaphragm Muscle: Function and Dysfunction

There can be many reasons that damage the function of the diaphragm, either transiently or permanently, involving one hemilate or both muscle portions. The diaphragm is associated only with breathing, but many other functions are related to it. The patient is not always aware of the presence of diaphragmatic dysfunction, and it is not always immediate to identify non-respiratory diaphragmatic symptoms. Pseudoanginal pain, night sweats, difficulty memorizing, or muscular and visceral problems of the pelvic floor are just some of the disorders linked to reduced diaphragmatic contractility. A decline in respiratory contractile force can be the basis for further pathological conditions that can increase the rate of mortality and morbidity. The article reviews the possible symptoms that may be presented by the patient, which are not necessarily related to lung function.

Difficult Respiratory Weaning after Cardiac Surgery: A Narrative Review

Respiratory weaning after cardiac surgery can be difficult or prolonged in up to 22.7% of patients. The inability to wean from a ventilator within the first 48 h after surgery is related to increased short- and long-term morbidity and mortality. Risk factors are mainly non-modifiable and include preoperative renal failure, New York Heart Association, and Canadian Cardiac Society classes as well as surgery and cardio-pulmonary bypass time. The positive effects of pressure ventilation on the cardiovascular system progressively fade during the progression of weaning, possibly leading to pulmonary oedema and failure of spontaneous breathing trials. To prevent this scenario, some parameters such as pulmonary artery occlusion pressure, echography-assessed diastolic function, brain-derived natriuretic peptide, and extravascular lung water can be monitored during weaning to early detect hemodynamic decompensation. Tracheostomy is considered for patients with difficult and prolonged weaning. In such cases, optimal patient selection, timing, and technique may be important to try to reduce morbidity and mortality in this high-risk population.