Critical care medicine
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Determining adequacy of mechanical ventilation is as important during CPR as in a more stable situation (such as, a patient on a ventilator in an ICU). Yet, such assessment during CPR usually only means listening for breath sounds, checking chest excursion, and blood gases. Exhaled tidal volume (VT) was measured on 45 intubated adult patients during resuscitation using a Wright's spirometer attached to a T-valve above the endotracheal tube. ⋯ Our findings suggest that lung compliance is markedly reduced within a short time after cardiac arrest. Fifty-five % of patients in this series could not be adequately oxygenated (PaO2 less than 50 torr) despite an FIO2 of 0.8 and adequate ventilation. Due to the reduced cardiac output during CPR causing venoarterial shunting, it is speculated that pulmonary edema is the most plausible explanation for this observation.
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Critical care medicine · Feb 1983
Comparative StudyEffect of the dynamic response of transducer-tubing system on accuracy of direct blood pressure measurement in patients.
The dynamic responses of 3 transducer-tubing systems (TTS) were documented using square and sine wave generators. The TTS tested were P23 ID with 5 feet tubing (P23-5'), P23 ID with 6 inches tubing (P23-6") and P50A transducer with no tubing (P50). Natural frequencies were 45, 33, and 7 Hz for P50, P23-6", and P23-5', respectively. ⋯ However, the differences were greater with radial, compared to brachial arterial cannulation (p less than 0.02). There were no differences in systolic pressures measured with P23-6" and P50. There were no differences in diastolic or electronic mean pressures recorded by the 3 TTS.
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One hundred seventy-one patients admitted to a Medical ICU and who received treatment for respiratory failure with mechanical ventilation were studied for the development of pulmonary barotrauma (PBT) as manifested by pneumomediastinum, subcutaneous emphysema, or pneumothorax. Fourteen patients (8%; group A) developed this complication; they were younger, had higher maximal peak inspiratory airway pressures (PIP); and higher levels of maximal PEEP. We conclude that for medical patients treated for respiratory failure with mechanical ventilation, the incidence of PBT is 8% and that younger age, higher levels of PIP and PEEP seem to pose an increased risk for developing PBT.
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Critical care medicine · Feb 1983
Tidal volume and airway pressure on high frequency jet ventilation.
The principle of jet injector indicates that large tidal volumes may be delivered on high frequency jet ventilation (HFJV) without increasing airway pressure. Fifteen dogs were ventilated on HFJV in 2 separate experiments. In the first one, tidal volume was maintained constant at 10 ml/kg, while PEEP, respiratory rate, and cannula size were changed in 16 different experimental conditions. ⋯ Tidal volume was twice as high with the 1.62 mm injector, as compared to the 1.06 mm injector, although resistances are 6 times higher with the smaller injector. The difference is related to the higher entrainment, which is observed when jet flow velocity increases, as is the case when the injector cannula is smaller. The experiments confirmed that HFJV follows the physical principles of jet mixing and entrainment.
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Critical care medicine · Feb 1983
Emergency cricothyroidotomy in the patient with massive neck swelling: Part 1: Anatomical aspects.
A method for localizing the hyoid bone in normal adult and children subjects is presented. The reliability of this calculated value in permitting localization of the hyoid was examined in 200 adult subjects in relationship to age, sex, neck size, and ethnic origin. ⋯ It was found to be a constant and remarkably predictable dimension which was unaffected by any of these variables. Because the hyoid serves as a frame from which the respiratory passage is suspended, it can be easily located and used to stabilize and retract superiorly and anteriorly the larynx and trachea, allowing easier access to these structures by a tracheotomy or cricothyroidotomy in the patient with massive neck swelling where emergency tracheotomy or cricothyroidotomy are difficult.