The Pulmonary Circulation In Ards

The acute respiratory distress syndrome (ARDS) is characterised by non-hydrostatic pulmonary oedema and refractory hypoxaemia, and complicates up to 25 of cases of the systemic inflammatory response syndrome The consensus definitions of ARDS and acute lung injury (ALI) are shown in table 14.2. PHT with increased pulmonary vascular resistance is common, even when systemic vascular resistance is low. The degree of pulmonary arterial hypertension is usually mild to moderate but promotes the...

Endotracheal intubation

Cardiopulmonary arrest and deteriorating consciousness are absolute indications for intubation and assisted ventilation. Hypercapnia, acidosis, and clinical signs of severe disease at presentation may not require immediate intubation before an aggressive trial of conventional bronchodilator therapy.57 58 Conversely, progressive deterioration with increasing distress or physical exhaustion may warrant intubation and mechanical ventilation without the presence of hypercapnia. Once it has been...

P Phipps C S Garrard

Most asthma exacerbations are managed in the community or emergency department while the more severe cases that fail to respond to bronchodilator and anti-inflammatory therapy require admission to high dependency (HDU) or intensive care units (ICU). Worldwide asthma prevalence is increasing, and with that the total number of admissions to hospital and intensive care. Although the time between the onset of symptoms and the requirement for ventilation is becoming shorter, the outcome is improving...

Topical drug delivery to the ventilated patient

Mechanical ventilation, whether invasive or non-invasive, may compromise the delivery of bronchodilator aerosols. The amount of nebulised drug reaching the airways depends on the nebuliser design, driving gas flow, characteristics of the ventilator tubing, and the size of the endotracheal tube.47 71 Drug delivery may vary from 0 to 42 in ventilated patients.72 The presence of humidification alone may reduce drug deposition by as much as 40 , but may be reversed by the addition of a spacer...

Recognising The Need For Ventilatory Support

The recognition that MV is required is commonly an end of the bed assessment by an experienced clinician. No one clinical feature or investigation is absolute except respiratory arrest or loss of consciousness.20 In most cases failure to improve with medical treatment in the hours following admission triggers ICU referral. Late failure several days after admission to hospital is less common and may indicate a worse prognosis.24 In many, a downward spiral of increasing carbon dioxide retention...

Assessment Of Severity

For the purposes of epidemiological studies, the definition of severe CAP as CAP needing ICU admission is adequate. In practical management terms, however, a more detailed method of assessment is needed. Severe CAP is almost always a multiorgan disease and patients with severe CAP at presentation will either already have, or will be rapidly developing, multiple organ failure. It is important that respiratory and other front line physicians appreciate this aspect of the disease. Apparent...

Bronchoscopy in specific conditions

The microbiological yield from bronchoscopy is low (13-48 ) in ventilated patients with community acquired pneumonia (CAP), possibly because of the frequency of antibiotic administration before admission to the ICU.28-30 By contrast, patients who have been mechanically ventilated for several days generally have extensive colonisation even of the lower respiratory tract. In these patients with suspected VAP, negative microbiological culture predicts the absence of pneumonia but false positives...

Clinical Factors Affecting Metabolic Rate And Oxygen Consumption

The cellular metabolic rate determines Vo2. The metabolic rate increases during physical activity, with shivering, hyperthermia and raised sympathetic drive (pain, anxiety). Similarly, certain drugs such as adrenaline4 and feeding regimens containing excessive glucose increase Vo2. Mechanical ventilation eliminates the metabolic cost of breathing which, although normally less than 5 of the total Vo2, may rise to 30 in the catabolic critically ill patient with respiratory distress. It allows the...

Respiratory muscle strength

Originally the tension of the respiratory muscles was tested in normal subjects by taking maximum pressure measurements at the mouth (Pimax),1617 while oesophageal and gastric balloon catheters allow the study of diaphragmatic strength. Contractions of the diaphragm can be obtained by electric or magnetic stimulation of the phrenic nerves.1819 In the intubated patient maximal pressure generation can be assessed during occluded maximal manoeuvres and this can be simply performed as the...

Inhaled Vasodilators

Nitric oxide (NO) is a free radical gas produced constitutively in the lung by nitric oxide synthase from L-arginine, NADPH, and oxygen. Endothelial cells constitutively release NO, causing pulmonary vasodilation primarily via the secondary messenger cyclic guanosine monophosphate. ARDS is characterised by ventilation-perfusion mismatching which produces arterial hypoxae-mia that may in part be caused by disordered endogenous NO activity. Patients with ARDS commonly have mild pulmonary...

Mask continuous positive airway pressure CPAP and noninvasive ventilation NIV

In spontaneously breathing patients the application of low levels of mask CPAP (3-8 cm H2O) may improve respiratory rate, dyspnoea, and work of breathing in asthma, particularly if there is evidence of smoking related lung disease.20 54 55 There is a danger that CPAP may worsen lung hyperinflation. If patients are intolerant of the mask or do not derive benefit, CPAP should be withdrawn. In hypercapnic patients CPAP alone may not improve ventilation. Few studies have looked specifically at NIV...

Inhalation Injury Epidemiology

Inhalation injury can be thermal and or chemical. It accompanies severe burns in up to 35 of those admitted to burn centres and accounts for 50-70 of burn related deaths.37-39 The first comprehensive description of inhalation injury resulted from the 1942 Boston Coconut Grove fire in which 491 people died.40 Furthermore, in the aftermath of the 2001 World Trade Center terrorist attack in New York, inhalation injury was the most frequent reason that survivors sought medical attention.41...