Extracorporeal membrane oxygenation (ECMO) for severe acute respiratory failure was proposed more than 40 years ago. Despite the publication of the ARDSNet study and adoption of lung protective ventilation, the mortality for acute respiratory failure due to acute respiratory distress syndrome has continued to remain high. This technology has evolved over the past couple of decades and has been noted to be safe and successful, especially during the worldwide H1N1 influenza pandemic with good survival rates. The primary indications for ECMO in acute respiratory failure include severe refractory hypoxemic and hypercarbic respiratory failure in spite of maximum lung protective ventilatory support. Various triage criteria have been described and published. Contraindications exist when application of ECMO may be futile or technically impossible. Knowledge and appreciation of the circuit, cannulae, and the physiology of gas exchange with ECMO are necessary to ensure lung rest, efficiency of oxygenation, and ventilation as well as troubleshooting problems. Anticoagulation is a major concern with ECMO, and the evidence is evolving with respect to diagnostic testing and use of anticoagulants. Clinical management of the patient includes comprehensive critical care addressing sedation and neurologic issues, ensuring lung recruitment, diuresis, early enteral nutrition, treatment and surveillance of infections, and multisystem organ support. Newer technology that delinks oxygenation and ventilation by extracorporeal carbon dioxide removal may lead to ultra-lung protective ventilation, avoidance of endotracheal intubation in some situations, and ambulatory therapies as a bridge to lung transplantation. Risks, complications, and long-term outcomes and resources need to be considered and weighed in before widespread application. Ethical challenges are a reality and a multidisciplinary approach that should be adopted for every case in consideration.
Endotracheal intubation is one of the most common, yet most dangerous procedure performed in the intensive care unit (ICU). Complications of ICU intubations include severe hypotension, hypoxemia, and cardiac arrest. Multiple observational studies have evaluated risk factors associated with these complications. Among the risk factors identified, the choice of sedative agents administered, a modifiable risk factor, has been reported to affect these complications (hypotension). Propofol, etomidate, and ketamine or in combination with benzodiazepines and opioids are commonly used sedative agents administered for endotracheal intubation. Propofol demonstrates rapid onset and offset, however, has drawbacks of profound vasodilation and associated cardiac depression. Etomidate is commonly used in the critically ill population. However, it is known to cause reversible inhibition of 11 β-hydroxylase which suppresses the adrenal production of cortisol for at least 24 h. This added organ impairment with the use of etomidate has been a potential contributing factor for the associated increased morbidity and mortality observed with its use. Ketamine is known to provide analgesia with sedation and has minimal respiratory and cardiovascular effects. However, its use can lead to tachycardia and hypertension which may be deleterious in a patient with heart disease or cause unpleasant hallucinations. Moreover, unlike propofol or etomidate, ketamine requires organ dependent elimination by the liver and kidney which may be problematic in the critically ill. Lately, a combination of ketamine and propofol, “Ketofol”, has been increasingly used as it provides a balancing effect on hemodynamics without any of the side effects known to be associated with the parent drugs. Furthermore, the doses of both drugs are reduced. In situations where a difficult airway is anticipated, awake intubation with the help of a fiberoptic scope or video laryngoscope is considered. Dexmedetomidine is a commonly used sedative agent for these procedures.
Background:Confirmation of placement of Double lumen endobronchial tubes (DLETT) and bronchial blockers (BBs) with the pediatric fiberoptic bronchoscope (FOB) is the most preferred practice worldwide. Most centers possess standard adult FOBs, some, particularly in developing countries might not have access to the pediatric-sized devices. We have evaluated the role of preintubation airway assessment using the former, measuring the distance from the incisors to the carina and from carina to the left and right upper lobe bronchus in deciding the depth of insertion of the lung isolation device.Methods:The study was a randomized, controlled, double-blind trial consisting of 84 patients (all >18 years) undergoing thoracic surgery over a 12-month period. In the study group (n = 38), measurements obtained during FOB with the adult bronchoscope decided the depth of insertion of the lung isolation device. In the control group (n = 46), DLETTs and BBs were placed blindly followed by clinical confirmation by auscultation. Selection of the type and size of the lung isolation device was at the discretion of the anesthesiologist conducting the case. In all cases, pediatric FOB was used to confirm accurate placement of devices.Results:Of 84 patients (DLETT used in 76 patients; BB used in 8 patients), preintubation airway measurements significantly improved the success rate of optimal placement of lung isolation device from 25% (11/44) to 50% (18/36) (P = 0.04). Our incidence of failed device placement at initial insertion was 4.7% (4/84). Incidence of malposition was 10% (8/80) with 4 cases in each group. The incidence of suboptimal placement was lower in the study group at 38.9% (14/36) versus 65.9% (29/44).Conclusions:Preintubation airway measurements with the adult FOB reduces airway manipulations and improves the success rate of optimal placement of DLETT and BB.
Umbilical cord blood gas along with the Apgar score is a useful tool to assess fetal well-being. Both umbilical artery and venous blood samples should be obtained, especially in case of fetal distress, to differentiate placental insufficiency from cord abnormalities. There is a strong correlation between umbilical cord gas abnormalities and fetal morbidity and mortality, but no proven predictive value has been found. Choice of anesthesia for labor analgesia and cesarean section and its effect on umbilical cord gas has been extensively studied but failed to show any consistent correlation. Factors that are deemed predictive of decreasing umbilical arterial pH are maternal body mass index (BMI), noncephalic presentation, spinal start to delivery interval, uterine incision to delivery, and maximum reduction in blood pressure from baseline.
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