Does hypoxia or hypercarbia independently affect resuscitation from cardiac arrest?

STUDY OBJECTIVE: In a previous cardiopulmonary resuscitation (CPR) study in swine, ventilation was associated with improved rate of return of spontaneous circulation (ROSC) compared with nonventilated animals, which had greater hypoxia and hypercarbic acidosis. We used the same model to determine the independent effect of hypoxia and hypercarbic acidosis on ROSC after cardiac arrest. DESIGN: Laboratory model of cardiac arrest. SETTING: University teaching hospital laboratory. PARTICIPANTS: Domestic swine (23 to 61 kg). INTERVENTIONS: Twenty-four swine were randomly assigned to three groups receiving ventilation during CPR with 85% O2/15% N2 (control), 95% O2/5% CO2 (hypercarbia), or 10% O2/90% N2 (hypoxia). All animals had ventricular fibrillation for 6 min without CPR, then CPR with one of the ventilation gases for 10 min, then defibrillation. Animals without ROSC received epinephrine, 85% O2, CPR for another 3 min, and defibrillation. MEASUREMENTS AND RESULTS: During the tenth minute of CPR, the hypercarbic group had more mean (SD) arterial hypercarbia than the control group (PCO2, 47 +/- 6, compared with 34 +/- 6; p < 0.01), and greater mixed venous hypercarbia (PCO2, 72 +/- 14, compared with 59 +/- 8; p < 0.05), while mean arterial and mixed venous PO2 was not significantly different. The hypoxic group had significantly less mean arterial (43 +/- 9 compared with 228 +/- 103 mm Hg) and mixed venous (22 +/- 5 compared with 35 +/- 7 mm Hg) PO2 when compared with the control group (p < 0.01), while mean arterial and mixed venous PCO2 were not significantly different. Thus, the model succeeded in producing isolated hypercarbia without hypoxia in the hypercarbic group and isolated hypoxia without hypercarbia in the hypoxic group. The rate of ROSC was 6/8 (75%) for the control group, 1/8 (13%) for the hypercarbic group, and 1/8 (13%) for the hypoxic group (p < 0.02). CONCLUSIONS: Both hypoxia and hypercarbia independently had an adverse effect on resuscitation from cardiac arrest. In this model with a prolonged interval of untreated cardiac arrest, adequate ventilation was important for resuscitation.

Changes in arterial and mixed venous blood gases during untreated ventricular fibrillation and cardiopulmonary resuscitation.

This investigation was designed to evaluate the changes in arterial and mixed venous acid-base conditions during untreated ventricular fibrillation and after institution of cardiopulmonary resuscitation (CPR). Fifty-two swine (weight: 25-40 kg) were studied after induction of ventricular fibrillation. In a subgroup of 10 animals, 10-min CPR trials were performed. Arterial and mixed venous blood gases were monitored at baseline, after 5 min of untreated ventricular fibrillation (nonintervention interval) and after 10 min of mechanical CPR. Standard CPR was performed at compression rates of 100/min with a 60% duty cycle. Arterial pH, Pco2, and HCO3 were unchanged when baseline values were compared with those obtained after 5 min of untreated ventricular fibrillation, while arterial Po2 decreased from 81 to 69 torr. Mixed venous pH decreased from 7.41 to 7.35, Pco2 increased from 43 to 48 torr, Po2 decreased from 40 to 38 torr and HCO3 decreased from 28 to 26 mEq/l (P < 0.05). Although these changes were statistically significant, many remain in the normal range. Both arterial and mixed venous pH and HCO3 fell further after 9 min of CPR and Pco2 increased (P < 0.05). Alterations in mixed venous pH and Pco2 were more apparent than corresponding changes in arterial blood gas composition. We conclude that untreated cardiac arrest may be accompanied by normal arterial and mixed venous blood gas levels. Tissue acidosis is only revealed after tissue perfusion is restored and is most accurately reflected in the mixed venous blood gas composition. This apparent paradox provides insight into the relationship between tissue perfusion and arterial and mixed venous acid-based composition.

A structured approach to clinical education in a dietetic curriculum.

The successful integration of clinical and didactic elements to achieve a well coordinated clinical education program is a complex, ongoing task in undergraduate dietetics education, involving both educational and managerial considerations. One effort to achieve improvements in these two areas was the development of a structured learning experience recently field tested with undergraduate dietetics students and clinical dietitians during clinical rotations. The structured experience defined roles, responsibilities, and activities for students, clinical dietitians, and course instructors and included scheduled review meetings attended by all participants. It was implemented with nine students during pediatric rotations. At the end of the course, students completed a standardized course evaluation form to assess course content, educational strategies, and effectiveness. They also rated the structured rotation, unstructured rotations, and their "ideal" rotation on 16 instructional factors. Clinical dietitians were interviewed by the course coordinator to elicit reactions and commitment to future participation. When it was compared with the traditional, non-structured approach utilized in surgery, gastroenterology, obesity/diabetes, and cardiovascular disease rotations, the structured learning experience received superior evaluations by participating students and dietitians. Correlations between ratings of structured, non-structured, and "ideal" approaches indicated directions for further educational and managerial improvements.

A nutrition/health training program for Peace Corps volunteers.

Nutrition and health education is a crucial component of the overall mission of the Peace Corps program. Individuals selected to work as Peace Corps volunteers need to be well prepared to perform this complex and challenging job in recipient countries. This article presents a model for a training program for Peace Corps trainees that was conducted over a 5-week period. The program was planned in accordance with some specific training guidelines that were provided by the Peace Corps. The trainees included nine women ranging in age from 22 to 61 years with diverse backgrounds; however, all had a BA/BS in a health-related discipline. Training curriculum included fundamental nutrition and health-related areas: basic nutrition, foods, clinical nutrition, maternal and child health, communicable diseases and sanitation, health strategies, and community development. Fifty percent of the curriculum was devoted to "hands-on" practical and clinical activities. Maternal and child health was emphasized in the training curriculum as this is an area of concern in all developing countries. The trainees were evaluated by weekly quizzes as well as completion of a special project involving applications of all their newly acquired skills. Implications of the training program are discussed.

[HIV infection es IgA nephropathy]. / A HIV-fertózés és az IgA nephropathia.

Similar immunological abnormalities exist in IgA nephropathy and HIV infection and several IgA nephropathy cases were reported in HIV-infected patients. To estimate the number of HIV-infected patients in IgA nephropathy, 80 patients with IgA nephropathy were studied for HIV-1 and HIV-2 antibody seropositivity. Although they failed to detect HIV positivity among their IgA nephropathy patients, because of the increasing number of people are being infected with HIV, the screening of IgA nephropathy patients for HIV infection would warrant.

Influence of different half-field stimulations on the pattern reversal visually evoked cortical potential.

In 30 healthy subjects the visually evoked cortical potential following full-field and upper, lower, temporal and nasal half-field pattern-reversal stimulation was registered. No significantly differing latencies for peak N90 were to be seen. The responses of peak P120 for upper half-field stimulation showed a significantly longer latency than for full-field, lower, temporal and nasal half-field stimulation. Responses to upper and lower half-field stimulation showed no potential reversal. Nasal and temporal half-field stimulation evoked responses with no significantly differing P120 latencies.

Amplitudes of visually evoked cortical responses due to full-field stimulation and to stimulation with four half-fields.

In 30 healthy subjects the VECP following full-fields, upper, lower, nasal and temporal half-field stimulation was recorded. The full-field amplitudes is significantly larger than each of the half-field responses. For peak P120, the amplitudes following lower half-field stimulation is significantly larger than the amplitude due to upper, nasal and temporal half-field stimulation. The sum two half-field amplitude is significantly larger than the full-field response.

[Motion-onset visually evoked potential with nasal and temporal half- and full-field stimulation]. / Durch Bewegungsbeginn visuell evozierte Potentiale bei Stimulation von nasalen und temporalen Halbfeldern sowie bei Ganzfeldreizung.

The known proportional increase in the amplitude of the pattern reversal visually evoked potential (VEP) with increasing stimulus area does not occur for the motion-onset VEP. When the stimulus area of the total field (6 degrees x 6 degrees) is compared to that of the half-field (6 degrees x 3 degrees), the N200 amplitude of the motion-onset VEP is not changed proportionally but remains almost constant. Reducing the pattern contrast beyond the saturation value for the motion-VEP yields essentially the same results. Contrary to the pattern reversal VEP, the amplitudes of the motion-onset VEP are found to be more pronounced for the nasal than for the temporal hemiretina. Our results support the notion of a genuine difference between the pattern- and the motion-analyzing visual system.

The choice of thrombolytic agents in the emergency department.

STUDY OBJECTIVE: To assess the choice of thrombolytic agents in emergency departments and whether administrators and third-party payers are influencing choices because of cost differences. DESIGN: A telephone survey. TYPE OF PARTICIPANTS: ED medical directors, stratifying for hospital ownership, size, and regions of the United States. MEASUREMENTS AND MAIN RESULTS: One hundred twenty-three ED medical directors completed the interview. Findings indicate that formularies include recombinant tissue-type plasminogen activator (rt-PA) in 94.3% of surveyed hospitals and streptokinase in 63.4%. Public hospitals were significantly less likely to have rt-PA on the formulary (P = .0001). Based on payer type, 68.9% to 77.5% of patients requiring thrombolysis receive rt-PA, with approximately 15% of EDs using it for 1% to 25% of patients and an additional 15% using it for 26% to 50% of patients. Fourteen medical directors (11%) reported that they delay treatment with rt-PA until authorization is provided by the health maintenance organization, and 40% indicated they would change their choice of agents if rt-PA was denied. Cardiologists were the primary decision makers regarding thrombolytic agents in all types of hospitals. CONCLUSION: Although rt-PA is the most frequently selected thrombolytic agent, significant practice variations exist among hospitals. To avoid interference from third-party payers and administrators, physicians may need to make decisions regarding such expensive agents in more objective forums (eg, pharmacy and therapeutics committees) and be better prepared to defend the resulting practice guidelines.

Composite hyoid-sternohyoid interposition graft in the surgical treatment of laryngotracheal stenosis.

This article reports six patients with severe laryngotracheal stenosis. The causes of stenosis were tracheotomy (two cases); prolonged endotracheal intubation (one case); laryngeal trauma (two cases); and surgery with postoperative chemo- and radiotherapy, addressing a thyroid gland follicular adenocarcinoma (one case). Two patients were already tracheotomized. The main postoperative complication was necrosis of the graft in a female patient who had previously undergone treatment for thyroid follicular adenocarcinoma. All patients were decannulated 6 months postoperatively. Five patients were then regularly followed up, but we lost contact with one patient. Comparison between pre- and postoperative pulmonary function testing revealed an increased maximum inspiratory flow (Vi max50) in five cases between 0.57 l/s and 2.18 l/s. A helical scan with 3-dimensional reconstruction of the cervical area in four patients confirmed the presence and preservation of the hyoid bone graft. Four patients remained satisfied with their postoperative voice quality, one patient was dissatisfied, and one patient was not followed up. This technique is effective in adults with severe laryngotracheal stenosis, restricted to the first tracheal rings, providing one takes into consideration the main contraindications of the procedure: past history of radiotherapy and thyroid surgery.

Application of the Cardiotrak pacemaker monitor to prehospital care.

The Cardiotrak is a small, lightweight device originally developed for use by pacemaker patients to transmit their electrocardiograms (ECGs) by telephone to their doctor or to a hospital. The Cardiotrak seemed well suited for use by paramedics and was field tested on 76 patients. In 69 patients, clear ECGs were transmitted with ease; in the remaining seven, only minor, correctable problems were noted. The Cardiotrak appears to have advantages over other devices used to transmit ECGs to base station hospitals from paramedics.

Esophageal perforation following use of esophageal obturator airway (EOA).

Esophageal perforation following use of the esophageal obturator airway (EOA) has been reported in a small number of patients. However, it has generally been discovered only in the presence of obvious clinical signs in patients otherwise resuscitated from cardiac arrest. Since it may well be overlooked in patients who succumb following the combined insult or primary cardiac arrest and secondary esophageal perforation, the true incidence of this adverse consequence of EOA use is unknown. We present a case of esophageal intubation with the EOA, and review in detail previous reported cases. We further suggest possible mechanisms leading to this catastrophic consequence of intubation with the EOA, and comment on its significance with regard to the controversy over EOA versus endotracheal (ET) tube training for paramedic pre-hospital personnel.

The antrochoanal polyp.

The different varieties of choanal polyps are reviewed by the authors according to their implantation pedicle. Their histology, possible pathogenesis, the various symptoms, steps in the diagnostic procedure and differential diagnoses are also described. Finally, the various modes of treatment are discussed, focussing in particular on the surgical methods and the new possibilities offered by developments in the field of endoscopy.

Automatic mechanical device to standardize active compression-decompression CPR.

STUDY OBJECTIVE: To develop an automatic mechanical device capable of performing active compression-decompression (ACD) CPR in laboratory animals. DESIGN: A swine model was used to study standard and ACD CPR. One-minute periods of standard mechanical chest compressions were alternated with mechanical ACD CPR. SETTING: University hospital laboratory. INTERVENTIONS: A commercially available device that provided standard chest compressions only was modified to deliver ACD CPR. RESULTS: The absolute difference in intrapleural pressure and tidal volume almost doubled during ACD CPR compared with that with standard CPR. CONCLUSION: The presence of a greater negative change in intrapleural pressure confirmed that active decompression of the chest had occurred and that the device was capable of performing ACD CPR. The device provides consistent rate, depth, force, and duty cycle.

Effect of ventilation on resuscitation in an animal model of cardiac arrest.

BACKGROUND: The need for ventilation during the initial management of cardiac arrest is an important public health problem that is being debated. The present study was designed to determine whether ventilation affects return of spontaneous circulation from cardiac arrest in a swine model with an interval of untreated ventricular fibrillation of 6 minutes, as reported in witnessed out-of-hospital human cardiac arrest. METHODS AND RESULTS: Twenty-four animals were randomly assigned to two groups: one that received ventilation during the first 10 minutes of chest compression and one that did not. Coronary perfusion pressure and minute ventilation were continuously recorded. Arterial and mixed venous blood gases were measured at intervals. Return of spontaneous circulation was defined prospectively as an aortic systolic blood pressure of > 80 mm Hg for > 5 minutes and was the primary outcome variable. All animals were anesthetized, paralyzed, and intubated. Ventricular fibrillation was induced and persisted for 6 minutes without chest compression, followed by mechanical chest compression for 10 minutes and then attempted defibrillation. Animals without return of spontaneous circulation were given epinephrine, ventilation, and chest compression for an additional 3 minutes. Defibrillation was again attempted, and animals were assessed for return of spontaneous circulation. There were no significant differences between the two groups in baseline prearrest mean cardiac index, coronary perfusion pressure, or arterial and mixed venous blood gases. However, after 9 minutes of chest compression, significant differences were noted between the ventilated and nonventilated groups. The nonventilated group had significantly (P < .05) lower mean arterial PO2 (38 +/- 17 mm Hg compared with 216 +/- 104 mm Hg) and higher PCO2 (62 +/- 16 mm Hg compared with 35 +/- 8 mm Hg), lower mixed venous PO2 (15 +/- 7 mm Hg compared with 60 +/- 7 mm Hg). Nine of 12 (75%) of the ventilated animals, and only 1 of 12 (8%) of the nonventilated animals had return of spontaneous circulation after cardiac arrest (P < .002). CONCLUSIONS: In this animal model of cardiac arrest, ventilation was important for resuscitation. The importance of ventilation could be related to the prolonged duration of untreated ventricular fibrillation and the significantly greater hypoxia and hypercarbic acidosis found in the nonventilated animals.