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At least 775 records · Page 43Linked to original sources
PubMed1987

Influence of sequential pneumatic compression on postoperative venous function.

Sequential external pneumatic compression (SEPC) has been reported to decrease the incidence of acute deep venous thrombosis in postoperative patients by a direct mechanical action on the lower extremity veins and/or by inducing alterations in systemic fibrinolysis. To evaluate the effect of SEPC on venous function in the postoperative patient, pre- and postoperative venous capacitance (VC) and outflow (VO) were measured in a series of general surgical patients. In phase I, 17 limbs were evaluated in patients who had been fully ambulatory preoperatively and at complete bed rest postoperatively. VC decreased from 3.19 +/- 0.43 cc/100 cc of tissue (mean +/- standard error of the mean) preoperatively to 2.08 +/- 0.34 cc/100 cc of tissue postoperatively (p less than 0.05) and VO decreased from 87.2 +/- 10.6 cc/100 cc of tissue/min preoperatively to 58.1 +/- 8.7 cc/100 cc of tissue/min postoperatively (p less than 0.025). In phase II SEPC was begun preoperatively and continued for 24 hours postoperatively on one limb of 20 patients. SEPC prevented the decrease in VC and VO both in the pumped leg (VC-2.65 +/- 0.26 cc/100 cc of tissue preop, 2.40 +/- 0.18 cc/100 cc of tissue postop, p greater than 0.2; VO-72.3 +/- 5.9 cc/100 cc of tissue/min preop, 66.2 +/- 5.3 cc/100 cc of tissue/min postop, p greater than 0.2) and in the unpumped limb (VC-2.85 +/- 0.18 cc/100 cc of tissue preop, 2.41 +/- 0.24 cc/100 cc of tissue postop, p greater than 0.05; VO-66.1 +/- 5.2 cc/100 cc of tissue/min preop, 66.7 +/- 6.7 cc/100 cc of tissue/min postop, p greater than 0.5).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Influence of inspired oxygen concentration on acceleration atelectasis.

The USAF is developing an On Board Oxygen Generation System (OBOGS) for use in fighter aircraft. This study was conducted to determine the inert gas dilution requirements of the OBOGS necessary to prevent acceleration atelectasis. Human subjects were exposed to either 21, 50, 70, 82.5, 95 or 100% inspired oxygen, along with an increased +Gz Simulated Aerial Combat Maneuver (SACM) profile using the USAF School of Aerospace Medicine human centrifuge. The SACM profile utilized four +4.5z peaks (136 s at this +Gz) superimposed on a +3 Gz baseline, representing a total ride time of 276 s. A significant reduction in vital capacity (VC) occurred at inspired oxygen concentrations of 70% and greater. The addition of 5% argon (a natural product of OBOGS) to pure oxygen did not reduce the magnitude of acceleration atelectasis observed, nor the severity of breathing symptoms. A 30-s exposure to positive pressure breathing at 30 mm Hg during the end of the SACM reduced the level of VC reduction caused by subjects breathing 100% oxygen during +Gz.

Acceleration↗
PubMed1986

Continuous external counterpressure during closed-chest resuscitation: a critical appraisal of the military antishock trouser garment and abdominal binder.

Blood flow during closed-chest CPR may result from variations in intrathoracic pressure rather than selective compression of the cardiac ventricles. During chest compression, the thoracic and abdominal cavities are subjected to positive pressure fluctuations. It has been suggested that compression of the abdomen may improve left heart outflow during CPR by limiting diaphragmatic movement or improving venous return. Abdominal compression has been performed experimentally with pneumatic abdominal binders and with the abdominal compartment of the conventional military antishock trouser (MAST) garment. The MAST garment might also improve cardiac output with CPR through an "autotransfusion" effect. In animal studies, MAST-augmented CPR has improved systolic pressures; it has not been shown to improve vital organ perfusion. In the only available clinical study, CPR with the MAST did not improve survival from prehospital cardiac arrest when compared with conventional CPR alone. If inflation of the MAST does produce blood displacement from the peripheral to the central venous circulation, such an effect may be detrimental in that the arteriovenous pressure gradients necessary for vital organ flow may be adversely affected. Inflation of the MAST during CPR may also adversely effect artificial ventilation. Selective abdominal binding also increases systolic pressures during CPR but does not improve subdiaphragmatic venous return. Although abdominal binding may increase common carotid flow, it has not been shown to improve cerebral or myocardial perfusion when compared with conventional CPR alone. These CPR adjunct techniques have not been shown to improve outcome from cardiac arrest and should remain experimental until further well-designed studies addressing regional vital organ flow and outcome of resuscitation are performed.

Abdomen↗
PubMed1986

Alternative approaches to external chest compression.

The finding that blood flow during external chest compression may be due to increased intrathoracic pressure, and the subsequent reporting of increased carotid blood flow with simultaneous ventilation and chest compression or with abdominal binding during CPR ignited a flurry of investigations into alternative approaches to CPR. A number of alterations of the conventional CPR technique were proposed, many resulting in improved hemodynamics when compared with standard CPR techniques in the same subject. However, some of the proposed methods increased cerebral blood flow but decreased myocardial perfusion. Others improved systolic pressures but decreased vital organ blood flow. More importantly, most studies with survival as an end point failed to show a benefit when alternative approaches to CPR were used. Therefore, it is unlikely that there will be significant changes in the recommendations for the use of adjuncts during CPR. Not all studies support the conclusion that blood flow during closed-chest compression is secondary to increased intrathoracic pressure. It is probable that in man there is a spectrum. In some individuals the predominant mechanism of blood flow during CPR may be cardiac and/or vascular compression, and in others flow may be secondary to an increased intrathoracic pressure.

Animals↗
PubMed1987

Efficacy of military antishock trousers in compensatory and decompensatory hemorrhagic hypotension.

The compensatory cardiovascular response to hemorrhage includes a baroreceptor-induced activation of the sympathetic nervous system resulting in an attempt to reestablish MAP through peripheral vasoconstriction. If the hypotension is not reversed this compensatory vasoconstriction will progress to a loss of vascular tone known as vascular decompensation. The primary purpose of the present study was to compare the effectiveness of military antishock trousers (MAST) applied during the compensatory and decompensatory stages of hemorrhagic hypotension. MAST pressures of 30, 50, 70, and 90 mm Hg were applied during control, compensation, and decompensation. The results showed that MAST pressures up to 90 mm Hg were ineffective at raising mean arterial blood pressure (MAP) when applied to normotensive dogs; MAP increased 62% when MAST were applied during compensation as the result of a significant augmentation of cardiac output (stroke volume and heart rate) with no change in TPR; and a modest increase in MAP from 40 to 55 mm Hg occurred when MAST pressure was increased to 70 mm Hg during decompensation, which was accounted for entirely on the basis of an increased total peripheral resistance with no significant change in CO.

Animals↗
PubMed1986

Shock.

Inevitably, a patient in shock will present to your office. The findings may be obvious, or they may show the more subtle changes of mild tachypnea, tachycardia, and/or changes in mental status. In either event, the perfusion pressure either has already decompensated or will do so momentarily. Whether you initiate therapy then and there might well determine whether your patient will survive. Accordingly, each office should have available for the pre-hospital management of shock those items listed in Table 3. As clinicians, you must be prepared to begin treatment in your office. Although the hospital, particularly the intensive or coronary care unit, is the appropriate setting for the management of shock, therapy must be initiated as soon as and wherever the diagnosis is made. In this situation, an ounce of prevention is indeed worth a pound of cure. Shock, whether it develops insidiously or precipitously, is a state of inadequate tissue perfusion that, if misdiagnosed or treated inadequately, will inevitably result in death.

Blood Volume↗
PubMed1987

Postmastectomy lymphedema treated with the Wright linear pump.

Fifteen patients with postmastectomy lymphedema of the arm were treated with the Wright linear pump, a programmable, gradient pressure, sequential, intermittent compression pump. The group comprised volunteers in whom conservative measures had failed. This is a phase II trial to determine the efficacy of the pump. All patients had subjective improvement. Objectively, all showed a reduction in edema, but this was of variable degree and depended on the amount of pre-existing lymphedema in the arm. The Wright linear pump is easy to use and treatment was well tolerated. No fluid overload occurred due to treatment and no other medical problems were encountered. The Wright linear pump seems more effective than other pneumatic intermittent compression pumps available.

Adult↗
PubMed1987

Regimen for improved effectiveness of intermittent pneumatic compression in deep venous thrombosis prophylaxis.

The incidence of deep venous thrombosis (DVT) was assessed in a series of 78 patients undergoing major surgical operations to compare the prophylactic effectiveness of intermittent sequential pneumatic compression alone with the simultaneous use of graduated compression stockings and intermittent sequential pneumatic compression. The diagnosis of DVT was determined with the I-125 fibrinogen-uptake test, Doppler ultrasound, maximum venous outflow by strain-gauge plethysmography, and contrast venography. The incidence of DVT in nonstockinged legs was 9% while that in the stockinged legs was 1%. The simultaneous use of graduated elastic compression stockings and intermittent pneumatic compression is more effective than pneumatic compression alone in the prevention of postoperative DVT.

Adult↗
PubMed1986

The pneumatic antishock garment: use in experimental acute cardiac tamponade.

Acute cardiac tamponade was created in a large animal model in an effort to investigate the hemodynamic and oxygen transport variables during the inflation of the pneumatic antishock garment (PASG) to two different pressures (60 and 80 mm Hg). Inflation of PASG to either pressure under these conditions had no significant effects on filing pressures to the right or left heart, cardiac index, arterial blood gases, oxygen delivery, indexed pulmonary, and systemic vascular resistances. We conclude in this animal model of acute cardiac tamponade that no beneficial or harmful effects were demonstrated during the application and inflation of the pneumatic antishock garment to 60 or 80 mm Hg.

Animals↗
PubMed1986

Trendelenburg versus PASG application--hemodynamic response in man.

Diminished venous return is the primary determinant of reduced cardiac output in hemorrhagic hypoperfusion. In this study the hemodynamic response of two therapies commonly employed to increase venous return in hemorrhagic hypoperfusion--pneumatic antishock garment (PASG) application and Trendelenburg (TREND) positioning--were compared in normovolemic man. Five patients had PASG pressure of 20 mm Hg compared with 10 degrees Trendelenburg, eight patients had 20 and 40 mm Hg PASG application compared with 10 degrees Trendelenburg. PASG application at both 20 and 40 mm Hg resulted in a significant increase in CVP (11.1 +/- 1.9 baseline to 16.0 +/- 2.7 PASG 40; p less than 0.01) left atrial pressure (LAP) (10.1 +/- 1.3 baseline to 14.4 +/- 1.8 PASG 20; p less than 0.01) pulmonary capillary wedge pressure (PCWP) (11.6 +/- 2.0 baseline to 16.8 +/- 3.4 PASG 40; p less than 0.01) and esophageal pressure (Pes) (5.0 +/- 0.8 baseline to 8.6 +/- 0.9 PASG 40; p less than 0.01). However, transmural right and left atrial pressure (RATP, LATP) and cardiac index (CI) were unchanged. Ten degrees of Trendelenburg resulted in no increase in CVP, PCWP, RATP, or LATP, but CI (2.67 +/- 0.07 baseline to 2.82 +/- 0.1 TREND; p less than 0.01) was significantly increased. Systemic vascular resistance index (570 +/- 46 TREND vs. 668 +/- 53 PASG 40; p less than 0.01) was significantly less in Trendelenburg compared to PASG at 40 mm Hg. The data demonstrate that elevation in CVP, LAP, and PCWP following PASG application is secondary to an increase in intrathoracic pressure (as measured by Pes).(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗