Animal research has revealed the main pathophysiological mechanisms by which positive pressure ventilation can cause pulmonary barotrauma accompanying the distention of the lungs, and ultimately lead to permeability pulmonary edema. The significance of these mechanisms in the clinical setting has been recognized in recent years, and the publication of studies on acute respiratory distress syndrome (ARDS) patients has focused attention on the importance of using methods of ventilation that do not cause barotrauma. Possible mechanisms behind barotrauma include the overdistention of the lungs by high peak airway pressures or large tidal volumes, shear stress caused by the repeated opening and closing of small airways or alveolar ducts, and the inflammatory process. The importance of preventing overdistention by limiting tidal volume, and preventing small airway closure by the use of positive end-expiratory pressure (PEEP) over the lower inflection point is now known. However, further studies into ventilation methods that minimize barotrauma are needed.

View full abstract

We assessed the skills of basic life support (BLS) maneuvers of the medical school students, and made the current problems of resuscitation teaching apparent. The subjects were the 5th year students who were before clinical training and two classes of the 6th year students who were after the training. As an objective structured clinical examination (OSCE), we imposed three minutes' manikin BLS on them. The required time for the first assessment, heart massage, ventilation, and other 15 measurements were obtained from the recordings of the manikin. Both classes of the 6th year students were more skillful than the 5th year students, probably because they received practical training more. However all subjects lacked quickness in their movements in 4-cycled set of 2:15 maneuvers. We conclude that the present training may improve each skill of BLS but may not facilitate efficient performance in combination. A BLS guideline should clearly indicate the standard time for each process.

View full abstract

Purpose: To evaluate a possibility that the brain temperature (brain T) monitoring can be predictive for prognosis immediately after severe brain damage.
Method: The brain temperatures of 41 patients with severe brain damage due to a various insults, including cerebrovasular accident, head trauma and cardiopulmonary arrest, were monitored. Simultaneously, bladder temperature (bladder T), intracranial pressure (ICP), oxygen saturation of the internal jugular venous blood (SjO₂) and systemic blood pressure were measured. Subsequently, the temperature gradients (ΔT) between the brain and bladder and the cerebral perfusion pressure (CPP) were calculated. The prognosis was retrospectively evaluated by Glasgow outcome scale (GOS). The perfusion volume and its geometry in the brain were measured by scintigrams.
Results: The patients with a persistently positive ΔT survived, having good recovery or suffered only moderate disability according to GOS. On the other hand, brain death occurred in the patients with continuously negative ΔT. The patients with fluctuating ΔT had a variable GOS. Differences in brain insults had no effect on these results. In patients with CPP of more than 50mmHg throughout the entire course of the measurement, the ΔT was constant with good correlation (r²=0.910). No correlation was identified in patients with CPP of less than 50mmHg (r²<0.50). The patients with a positive ΔT had a good cerebral perfusion volume (≥20ml·100g^-1·min^-1). On the other hand, in the patients with a negative ΔT, the brain perfusion volume was significantly diminished (≤10ml·100g^-1·min^-1). In the patients with a fluctuating ΔT, SjO₂ was helpful in evaluating the severity of brain damage.
Conclusion: Brain temperature monitoring is effective in making a prognosis of brain damage because brain temperature depends on the CPP and the cerebral blood flow.

View full abstract

There are two sensing systems in ventilators, namely a flow trigger system and a pressure trigger system to synchronize the spontaneous breathing of a patient. A flow trigger system requires constant oxygen “bias flow” and therefore assumed to spend more oxygen and to be less cost effective than a pressure trigger system. In order to compare the running cost of these two types, we measured oxygen expenditure of eight ventilators.
Each ventilator was connected to a test lung and set in a synchronized intermittent positive pressure (SIMV) mode. Oxygen expenditure was measured by a digital addition flow meter (Air-Water Co. Japan) after 30 minutes of mechanical ventilation with oxygen concentration of 100%, 60%, 40%, or 21%. In some ventilators, the expenditure was calculated from the internal pressure loss of an oxygen tank connected to them.
As a result ventilators were divided into two groups according to oxygen expenditure. A “low” expenditure group includes Servo 900C, Evita 2, and Servo 300, and a “high” expenditure group includes Bennett 740, T-Bird VSO₂, Bird 8400STi, and CV4000a. This result does not depend on the triggering system. In 100% oxygen, the maximum oxygen expenditure was recorded by a Bird 8400STi (16.98l·min^-1). This is more than three times higher than the smallest, record by an Servo 900C (4.10l·min^-1). Two of the three pressure trigger type ventilators showed higher oxygen expenditure than the flow trigger ones. This result may be attributed to the character of oxygen-air blenders or the structure of the ventilators. We calculated the reimbursement covered by the national health insurance system and the cost of oxygen used by the ventilators in condition of 100% oxygen for 200 days of operation per year. A Bird 8400STi was estimated to make about 540 thousand yen's annual loss to the hospital, while the “low” group may bring the income of 10-60 thousand yen per year.
In conclusion we call intensivists' attention to the oxygen costs of a long term ventilator therapy.

View full abstract

Right atrial thrombus is an infrequent but nevertheless life-threatening disease. We have detected right atrial thrombi by transesophageal echocardiography (TEE) in two patients with acute respiratory failure. The first patient was a 45-year-old male who was transferred to treat respiratory failure. In the ICU, he underwent TEE and was found to have some atrial thrombi in the right atrium. Although anticoagulant therapy was started, he passed away on the 5th ICU day. In the autopsy his lungs revealed many infarct lesions especially in the right lower lobe.
Another patient was a 65-year-old male who suffered from sudden dyspnea in a ward and was transported to the ICU. The right atrial thrombi was found by TEE, and heparin and urokinase were administrated immediately. Pulmonary scintigraphy showed perfusion defects in the right upper lobe. He was discharged on the 7th ICU day and was further evaluated in the ward. We conclude that TEE was useful in detecting atrial thrombi and in diagnosing pulmonary embolism in an ICU.

View full abstract

We report on acute intensive care of two cases of successful heart transplantation for dilated cardiomyopathy. After the surgery the patients were kept in a clean room where only limited number of staffs were allowed to enter.
We administered low dose of either dopamine or dobutamine to prevent heart failure. We also applied cardiac pacing with continuous infusion of isoproterenol to maintain heart rate. Our observation suggests that administration of atrial natriuretic peptide may have be effective for preservation of renal function in the two cases. Our management policy is summarized as follows: (1) to minimize chances of infection such as early removal of catheters and early implementation of physical rehabilitation in a clean room, (2) to extend conventional postoperative cares for hemodynamics with special emphasis on heart rate control, and (3) to carefully adjust immunosuppression therapy. Both patients recovered smoothly and were discharged from the ICU after thier endomyocardial biopsy studies revealed no sign of rejection.

View full abstract

Increased heart rate and elevated blood pressure were incidentally recorded with elevated end-tidal CO₂ pressure (P_ETCO₂) following dietary intake in a patient with amyotrophic lateral sclerosis (ALS) mechanically ventilated under predetermined condition.
A series of examinations were carried out to evaluate the effects of dietary ingestion on metabolic, hemodynamic and sympathetic conditions in the same patient, An amount of 400ml (400 kcal) of liquid food was given via a nasogastric tube. In response to diet intake, PaCO₂ rose from 33mmHg to 43mmHg on fixed ventilator setting in contrast with constant PaCO₂ on adjusted ventilator setting in which the initial level of P_ETCO₂ was maintained.
Carbon dioxide production (VCO₂) increased by 40% on both ventilator settings and oxygen consumption (VO₂) increased by 26% on fixed ventilator setting and by 38% on adjusted ventilator setting. Heart rate increased without elevation of mean blood pressure on adjusted ventilator setting, although the increases in heart rate and mean blood pressure were observed on fixed ventilator setting.
Both plasma concentrations of norepinephrine and dopamine were elevated after dietary ingestion but that of epinephrine remained unchanged.
Dietary ingestion provoked stimulated metabolic state and enhanced sympathetic activity. Elevation of blood pressure might be due to enhanced response of sympathetic nervous system to elevated PaCO₂, on a basis of a fact that patients with ALS are in a state of autonomic hyperreflexia. It must be taken into consideration that measurements of VO₂ and VCO₂ by indirect calorimetry after ventilator resetting such as an acute change in respiratory rate can not be used reliably for the evaluation of metabolic rate.

View full abstract

We developed an ICU database using an online database of the hospital ordering system, stored in the host computer. The patient data from the host computer are taken into a gateway machine (Mate Server NX^TM) by using a commercially available application, Microsoft Access^TM and then transferred to an ICU database through a local area network by using FileMaker Pro 4.0^TM on Power Macintosh^TM.
An ICU database consists of a patient database and a laboratory database. Many of the patient data are automatically inputted in selfmade mastertables of an ICU database from the host computer. An ICU doctor clicks a mouse on the tables and makes a patient summary with a keyboard.
An ICU database system linked to the hospital computer database system could be useful for electronic recording and saves labor of ICU doctors.

View full abstract