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Biomedical subjects

R M Nowak

Publications and source records attributed to R M Nowak.

At least 55 records · Page 3Linked to original sources
PubMed1987

Lactic acidosis during closed-chest CPR in dogs.

Survival after out-of-hospital cardiac arrest is intimately related to the time from cardiovascular collapse to the initiation of CPR, or downtime. Furthermore, the reperfusion technique that optimizes coronary and cerebral blood flow after cardiac arrest may also be dependent on downtime. Peak blood lactate levels have been shown to be unchanged throughout resuscitation and predictive of downtime in dogs subjected to cardiopulmonary arrest and open cardiac massage. The purpose of this study was to determine the course of arterial lactate levels in dogs subjected to a fibrillatory cardiopulmonary arrest and conventional closed-chest CPR (CCPR). Fourteen dogs were subjected to five minutes of cardiopulmonary arrest and 30 minutes of CCPR. Resuscitation was performed according to a standardized protocol. Arterial lactic acid samples were collected at timed intervals throughout the experiment. Mean arterial lactic acid levels increased significantly with each sampling interval during 30 minutes of CCPR (overall P less than .05). In nine dogs successfully resuscitated, there were no significant differences in mean arterial lactic acid levels after the return of spontaneous circulation (ROSC). Open-chest resuscitation after five minutes of ventricular fibrillation in dogs results in peak lactic acid levels that do not change significantly once internal cardiac massage is initiated. In contrast, CCPR in similarly arrested dogs does not appear to provide adequate tissue oxygenation and/or perfusion to prevent continuous lactic acid accumulation.

Acidosis, Lactic↗
PubMed1987

Selective venous hypercarbia during human CPR: implications regarding blood flow.

Thirty-five patients presenting to the emergency department in cardiopulmonary arrest had simultaneous measurement of central venous (cv) and arterial (a) blood gases during CPR with a pneumatic chest compressor and ventilator. The mean cv, arterial pH, and PCO2 values were markedly different (P less than .001). The mean pH gradient (pHa - pHcv) was .31 +/- .10 units and the mean PCO2 gradient (PcvCO2 - PaCO2) was 60.5 +/- 23.6 torr. This selective venous hypercarbia is probably due to a cardiac output that is inadequate to eliminate the CO2 produced from both residual aerobic metabolism and the buffering of anaerobically produced lactic acid. Central venous blood gases are probably a better reflection of actual tissue environment during prolonged cardiac arrest than are arterial blood gases.

Aged↗
PubMed1986

Catheter aspiration for simple pneumothorax.

A prospective study was conducted in the emergency setting to determine the efficacy of treatment of simple pneumothorax by catheter aspiration. Patients who were successfully treated were discharged to home. Sixty-one patients with a total of 76 pneumothoraces were involved in the study. The overall success rate was 75.6%, with an 82% success rate for needle-induced, 75% for traumatic, and 45% for spontaneous pneumothorax. The duration of symptoms, the size of the pneumothorax, the patient's age, and a prior history of pneumothorax did not affect the outcome. The poorest results were noted with spontaneous pneumothoraces, as would be expected since a majority of these patients have preexistent lung disease. Catheter aspiration of simple pneumothorax offers a cost-effective approach to this clinical problem.

Adult↗
PubMed1986

Aortic and right atrial pressures during standard and simultaneous compression and ventilation CPR in human beings.

Coronary perfusion pressure, as reflected by the diastolic aortic to right atrial (Ao-RA) pressure gradient, has been shown to correlate well with coronary blood flow during standard external CPR (SE-CPR) and is an important determinant of successful cardiac resuscitation. Few studies have documented such Ao-RA gradients in human beings, however. Twenty patients sustaining out-of-hospital cardiopulmonary arrests and basic cardiac life support were instrumented with thoracic aortic and right atrial catheters on arrival in the emergency department. The mean time from arrival in the ED to catheter placement was 16.5 +/- 6.0 minutes. With SE-CPR, peak systolic aortic and right atrial pressures were 73.7 +/- 20.2 mm Hg and 69.6 +/- 18.3 mm Hg, respectively. End diastolic aortic and right atrial pressures were 27.9 +/- 7.3 mm Hg and 20.3 +/- 7.2 mm Hg, respectively, with an end diastolic gradient of 7.9 +/- 9.1 mm Hg. Three patients had systolic Ao-RA gradients of more than 25 mm Hg, which is consistent with some cardiac compression as a mechanism of flow. Five patients also had one-minute trials of simultaneous compression and ventilation CPR (SCV-CPR). Ao-RA end diastolic gradients decreased in four of the five during SCV-CPR. No patient in this study was resuscitated successfully. We conclude that ED SE-CPR provides little coronary perfusion for victims of prehospital cardiac arrest. Although SCV-CPR has been shown to improve carotid blood flow in human beings, it appears to have an adverse effect on the already minimal myocardial perfusion provided by SE-CPR.

Aged↗
PubMed1986

Alternate therapy for traumatic pneumothorax in "pocket shooters".

Traumatic pneumothorax is a common complication of the IV drug abusers in Detroit who utilize the "pocket shot" (the central approach to the internal jugular vein). Fourteen patients who sustained a total of 16 pneumothoraces (two with bilateral collapse) and who underwent catheter aspiration of a simple pneumothorax (CASP) were studied prospectively. The sizes ranged from less than 10% to 100%. In addition, there was one tension pneumothorax and one pneumomediastinum. The 16 CASP procedures produced 13 successful lung expansions (82%). The remaining three were treated with tube thoracostomy and admission. Twelve of the 13 patients in whom the procedure was successful returned for followup, and all of these had 100% continued full expansion. CASP appears to be a safe, efficacious, and cost-effective treatment for the drug abuser with simple traumatic pneumothorax. With the current pressures of cost containment, this less-invasive approach with outpatient management should be studied as initial potential treatment for any simple pneumothorax.

Adult↗
PubMed1986

Use of bretylium tosylate as prophylaxis and treatment in hypothermic ventricular fibrillation in the canine model.

We conducted a study to determine if bretylium tosylate (BT) is effective in the prophylaxis and treatment of hypothermic ventricular fibrillation (VF) in the setting of various maneuvers thought to induce this lethal arrhythmia. Twenty-two mongrel dogs were cooled to 24 C after being placed in a cold room. At 24 C, a double-blinded placebo or BT solution was infused. The dogs then were removed from the cold. They underwent the following sequential maneuvers: oral endotracheal extubation and intubation, central line and nasogastric tube placement, vigorous movement, and Swan-Ganz catheter insertion. If VF ensued, arterial blood gases were drawn, and BT was given only if refractory to countershock and epinephrine. Of the dogs that were given placebo, six of 11 (55%) fibrillated with manipulation, as compared with one of 11 (9%) dogs pretreated with BT (P = .067). Three of the 11 dogs that received BT fibrillated within minutes of its infusion. In the placebo dogs that fibrillated, four required BT and two defibrillated with countershock alone or with epinephrine prior to achieving stable rhythms.

Animals↗
PubMed1986

Hyperkalemia during cardiac arrest and resuscitation in the canine model.

Although recent clinical reports have noted hypokalemia after resuscitation from cardiac arrest, extensive animal work indicates that potassium is released from cells during ischemia. This study was undertaken to define the changes that occur in serum potassium ion during cardiac arrest and resuscitation in a canine model. Fourteen dogs were subjected to 5 min of cardiac arrest followed by 30 min of closed-chest CPR (CCPR). Resuscitation was performed according to a standardized protocol. Serum potassium increased significantly (p less than .001) from baseline, remained elevated 5 min after return of spontaneous circulation (ROSC), but declined to baseline levels at 15 min post-ROSC. Increases in interstitial potassium would be expected to be even greater due to the poor exchange between interstitial and intravascular compartments during CCPR. Interstitial hyperkalemia may play a role in the genesis of wide-complex electromechanical dissociation and may explain the reported success of calcium chloride in treating this problem.

Animals↗
PubMed1986

Procedures for respiratory function.

The emergency practitioner has a wide array of procedures in his armamentarium for the diagnosis of pulmonary dysfunction. The combination of blood gas analysis, spirometry, peak expiratory measurements, and trans-tissue monitors, coupled with clinical and radiographic findings, can offer a concise picture of pulmonary status. Further emergency medicine research in these areas will provide exciting methods of assessing and monitoring treatment responses for patients with pulmonary dysfunction.

Blood Gas Analysis↗
PubMed1985

Lactic acidosis as a predictor of downtime during cardiopulmonary arrest in dogs.

Studies have shown that over 50% of cardiovascular deaths occur before hospitalization. A major factor associated with survival in cases of out-of-hospital cardiac arrest is the time from cardiovascular collapse to the initiation of cardiopulmonary resuscitation (CPR) or "downtime." The purpose of this study was to determine whether blood lactate levels could be used to predict downtime in the canine cardiac arrest model. Femoral arterial and Swan-Ganz catheters were placed in 22 mongrel dogs, and ventricular fibrillation was electrically induced. The dogs remained in ventricular fibrillation without ventilation for 5, 10, 15, 30, or 60 minutes. After the predetermined fibrillation time, a left anterolateral thoracotomy was performed, and open-chest cardiac massage was begun. Arterial and mixed venous lactate levels were determined for every 5 minutes during 30 minutes of cardiopulmonary resuscitation. The correlation coefficient between the mixed venous and arterial lactate levels was 0.96 or greater during all stages of resuscitation. Peak serum lactate level increased linearly in relation to downtime. The increase in lactate level was not evident until after CPR was begun, and it remained at peak levels or decreased insignificantly, despite optimal open-chest CPR. Linear regression analysis revealed that 84% of the variability in serum lactate levels could be explained by downtime differences. In this model, blood lactate level is a reliable and objective measure of downtime and may be a useful indicator of the adequacy of CPR if levels decrease or remain stable. The clinical implications of this study lie with the use of blood lactate levels in the emergency department to guide the aggressiveness of resuscitative efforts.

Acidosis↗
PubMed1985

Central venous and mixed venous oxygen saturation: comparison during canine open-chest cardiopulmonary resuscitation.

Mixed venous oxygen saturation (MVO2) is a valuable parameter in monitoring critically ill patients because it serves as an index of the adequacy of the oxygen delivery system. Mixed venous oxygen saturation as reflected by the easily obtainable central venous oxygen saturation (CVO2) may prove useful during cardiopulmonary resuscitation (CPR) as an indicator of both the adequacy of varying CPR regimens and the efficacy of pharmacological interventions. This study investigates the relationship between CVO2 and MVO2 and its clinical usefulness during CPR. Swan-Ganz and central venous catheters were placed in 20 mongrel dogs. Ventricular fibrillation was then induced and, after predetermined downtimes ranging from 5 to 60 minutes, thoracotomy was performed, and open-chest bimanual cardiac massage was started. Central venous and mixed venous blood-gas samples were drawn every five minutes during a 30-minute period of CPR. The correlation between CVO2 and MVO2 was 0.8719 (P less than 0.001) before arrest but deteriorated at all times during CPR with values ranging from 0.1589 (P = 0.542) to 0.5781 (P = 0.024). Although statistically significant at times, the correlation between CVO2 and MVO2 during CPR is not consistently high enough to enable the routine substitution of CVO2 for MVO2 in assessing the oxygen delivery system.

Animals↗
PubMed1985

Insulin and glucose levels during CPR in the canine model.

Cardiopulmonary arrest and resuscitation produces tremendous physiological stress with resultant biochemical derangements. We undertook this study to determine insulin and glucose levels during cardiopulmonary arrest in the canine model. Baseline insulin and glucose levels were obtained from an ascending aortic arch catheter in six mongrel dogs. Ventricular fibrillation was induced by an electrical stimulus and ventilation was terminated. After five minutes of fibrillation, cardiopulmonary resuscitation (CPR) was initiated using external, mechanical CPR and a continuous epinephrine infusion at 5 micrograms/kg/min. Serum insulin and glucose levels were repeated 15 minutes after beginning CPR. Mean blood glucose 15 minutes after initiation of resuscitation (379 +/- 114 mg/dL) was significantly increased from prearrest levels (124 +/- 29 mg/dL, P less than .01). Mean serum insulin 15 minutes after initiation of resuscitation (11.3 +/- 3.3 microU/mL) was significantly decreased compared to prearrest levels (16.2 +/- 6.0 microU/mL, P less than .05). During ischemia, the myocardium becomes dependent primarily on glucose as a source of energy. Inappropriately low insulin levels during CPR may adversely affect an already compromised myocardial glucose metabolism. Further investigation is needed to determine the utility of insulin infusion during CPR.

Animals↗
PubMed1985

Immediate emergency department external cardiac pacing for prehospital bradyasystolic arrest.

Approximately 25% of patients in prehospital cardiac arrest present in bradyasystolic rhythms, and their long-term prognosis is very poor. Our study was undertaken to determine the utility of immediate emergency department (ED) external cardiac pacing in this situation. Twenty patients presenting with bradyasystolic prehospital cardiac arrest were entered in the study. All received the usual advanced cardiac life support therapy, but also were externally paced immediately using an automated external defibrillator and pacemaker (AEDP). Only two of 20 patients showed evidence of electrical capture, and none developed pulses with pacing. Four of the 20 patients developed a sinus rhythm and blood pressure during resuscitation. Three survived to leave the ED, but none survived to leave the hospital. An increase in the rate of bradycardia and pulseless idioventricular rhythms that was independent of electrical capture or pharmacologic therapy was noted occasionally. Although survival was not enhanced using the AEDP, the device was reliable, easy to use, and free of complications. External cardiac pacing warrants further investigation in the prehospital setting.

Adult↗
PubMed1985

Comparison of central venous and arterial pH and PCO2 during open-chest CPR in the canine model.

Arterial blood gases are difficult to obtain during cardiopulmonary resuscitation (CPR) in human beings, and the possibility of venous sampling is raised frequently. The reliability of central venous gases as a substitute for arterial blood gases in assessing acid base status, however, has not been investigated adequately under conditions of CPR. Therefore, femoral arterial and central venous catheters were placed in 24 mongrel dogs, and ventricular fibrillation was electrically induced. After varying predetermined downtimes from five to 60 minutes, open-chest CPR was begun, and arterial and central venous blood gases were simultaneously drawn every five minutes during a 30-minute period. Arterial pH (pHa) was consistently higher than central venous pH (pHcv) by an average of .048 units. A significant correlation existed between the pHa and pHcv at all times during CPR, with an overall r = .9771 (P less than .0001). The difference between central venous PCO2 (PcvCO2) and arterial PCO2 (PaCO2) was 5.17 mm Hg prior to cardiac arrest, but it increased 300% to a mean of 15.51 mm Hg during CPR. Correction of pHcv using conventional methods to account for this respiratory component decreased the correlation between pHa and pHcv to r = .6905. The ability of pHcv to substitute for pHa was assessed, and showed a sensitivity of 100% when pHa of 7.2 was used as a criterion for treatment. In this model, pHcv is a sensitive indicator of pHa and it may be used to guide bicarbonate therapy. The increased PcvCO2 during CPR probably results from the marked tissue lactic acid production and subsequent shift of the bicarbonate buffer into free carbon dioxide.

Analysis of Variance↗