Mechanical ventilation is provided in intensive care unit when the  patient is unable to

maintain spontaneous  respiration on their own in order to sustain life.Weaning is a process

of  gradual  liberalization from the  ventilator support after  the  resolution of  primary illness.

Weaning failure is defined as failure in tolerating spontaneous  breathing trial (SBT ) or the

need for  invasive or non- invasive ventilation within 48 hours of extubation. Neuro-muscular

disease, nutritional deficiency,metabolic disturbance,Cardiac dysfunction and  respiratory

disease are the various causes of weaning failure.

Liu et al, conducted a study in critically ill patients and found that weaning  induced

pulmonary edema attributed to 40% of unsuccessful SBT. Although the patho-physiology of

weaning induced pulmonary edema remains complex ,transition from mechanical ventilator

support to spontaneous breathing leads to physiological changes like  increased pre-load

,after - load ,work of  breathing ,adrenergic tone  and  increased myocardial oxygen

consumption thereby leading  to elevated pulmonary venous pressure and pulmonary edema

effectuating weaning failure.Patients  with  borderline left  ventricular systolic and diastolic

function, Chronic obstructive pulmonary disease, especially with  positive cumulative fluid

balance are at increased risk  for  weaning failure. Weaning  failure  results  in  prolonged

ventilatory demand , lengthened  intensive care unit stay and  hence increased morbidity

and mortality.Since the  incidence of  weaning failure  remains high ,a profound  knowledge

regarding  the  risk  factors,pathogenesis ,prediction ,diagnosis and management of

weaning failure  is very  much essential to curtail it. Hence  a  detailed  assessment done

before  SBT, during  and  after  SBT could  help us  in preventing  weaning  failure.

Lung ultrasound score (LUS) is a useful tool  in  predicting weaning failure. Higher baseline

LUS  score and Loss of lung aeration during SBT are associated with high failure rates.A

LUS score < 13 % was associated with successful weaning. An integrated use of  lung usg,

diaphragmatic thickness fraction and trans -thoracic echo has shown a promising role in

predicting weaning  failure .Since there is no ideal single parameter to predict weaning

failure, a combination of methods is essential to assess neurology ,cardiovascular and

respiratory status.

Recently Thoracic fluid content, a novel parameter which  measures the whole fluid

(intravascular,extravascular)component in the thoracic cavity is analysed in predicting

weaning failure.A higher TFC value is associated with increased lung congestion and

hypervolemia, which is considered as a risk factor for difficult weaning.Thoracic fluid content

has advantages like easy measurement by the physician and paramedics, lack of  inter-

observer variations because of minimal fluctuations in the numerical value.

We hypothesize that Thoracic fluid content measured by cardiometry  has a promising role

and can be used as an adjuvant non invasive tool in  predicting weaning failure.Hence in our

study we combine  measuring the Thoracic fluid content along with Lung utrasound score

Echocardiography, Pulmonary vascular permeability index and Extravascular lung water

index to ascertain the efficacy of  thoracic fluid content  measured  by cardiometry  in

predicting  weaning failure .