Design and evaluation of a handheld impedance plethysmograph for measuring heart rate variability.

Heart rate variability (HRV) analysis from 10s ECGs has been shown to be reliable. However, the short examination time warrants a user-friendly system that can be used for ad-hoc examinations without normal preparation, unlike ECG. A handheld device has been developed that can measure ultra-short HRV from impedance plethysmographic recordings of the pulse wave in distal superficial arteries. The prototype device was made user-friendly through a compact, pen-like design and the use of integrated metal electrodes that were especially designed for dry operation. The main signal processing was performed by a digital signal processor, where the discrete heart beats were detected using a correlation algorithm that could adapt to individual pulse wave shapes to account for biological variation. The novel device was evaluated in 20 mainly young volunteers, using 10 s time-correlated ECG recordings as the reference method. Agreement between the two methods in measuring heart rate and root mean square of successive differences in the heart beat interval (RMSSD) was analysed using correlation coefficients (Pearson's R2), mean differences with 95% confidence intervals and 95% limits of agreement, and Bland-Altman plots. The correlation between the two methods was R2 = 1.00 and R2 = 0.99 when heart rate and RMSSD were measured, respectively. The Bland-Altman plots showed suitable agreement between the novel device and standard 10 s ECGs, which was substantiated by 95% limits of agreement of the difference of +/- 0.1 beats min(-1) and approximately +/- 10 ms for heart rate and RMSSD, respectively. Therefore the evaluation showed no significant systematic error of the novel device compared with ECG.

Rewarming from accidental hypothermia by extracorporeal circulation. A retrospective study.

OBJECTIVE: Twenty-six patients with accidental hypothermia combined with circulatory arrest or severe circulatory failure were rewarmed to normothermia by use of extracorporeal circulation (ECC). The aim of the present study was to evaluate our results. PATIENTS AND METHODS: The treatment of six female and 20 male patients (median age: 26.7 years; range 1.9--76.3 years) rewarmed in the period 1987--2000 was evaluated retrospectively. Hypothermia was related to immersion/submersion in cold water (n=17), avalanche (n=1) or prolonged exposure to cold surroundings (n=8). Prior to admission, the trachea was intubated and cardiopulmonary resuscitation (CPR) initiated in all patients with cardiorespiratory arrest (n=22), whereas in those with respiration/circulation (n=4) only oxygen therapy via a face mask was given. RESULTS: Nineteen of the 26 patients were weaned off ECC whereas seven died because of refractory respiratory and/or cardiac failure. Eight of the 19 successfully weaned patients were discharged from hospital after a median of 10 days. One patient died 3 days after circulatory arrest (complete atrioventricular block) resulting in severe cerebral injury. The remaining ten patients died following 1--2 days due to severe hypoxic brain injury (n=5), cerebral bleeding (n=1) or irreversible cardiopulmonary insufficiency (n=4). Based on the reports from the site of accident, two groups of patients were identified: the asphyxia group (n=15) (submersions (n=14); avalanche accident (n=1)) and the non-asphyxia group (n=11) (patients immersed or exposed to cold environment). Seven intact survivors discharged from hospital belonged to the non-asphyxia group whereas one with a severe neurological deficit was identified within the asphyxia group. CONCLUSION: Patients with non-asphyxiated deep accidental hypothermia have a reasonable prognosis and should be rewarmed before further therapeutic decisions are made. In contrast, drowned patients with secondary hypothermia have a very poor prognosis. The treatment protocol under such conditions should be the subject for further discussion.

[Rewarming of patients with accidental hypothermia with the help of heart-lung machine]. / Oppvarming av pasienter med aksidentell hypotermi ved hjelp av hjerte-lunge-maskin.

BACKGROUND: Different techniques have been used for treatment of victims with accidental hypothermia. We have used cardiopulmonary bypass (CPB) for rewarming hypothermic patients with circulatory failure or cardiac arrest. This report summarises our experiences with this patient group. MATERIAL AND METHODS: 23 patients, submersions (n = 15), avalanche (n = 1) and primary hypothermia (immersion/air cooling) (n = 7), were rewarmed using extracorporeal circulation with standard equipment for open-heart surgery. RESULTS: On a clinical basis, two patient populations could be identified; one group for whom asphyxia was probably present prior to and during cooling, and another group for whom asphyxia was unlikely. In the first group, one of 13 patients survived compared to the latter group where six out of ten survived. A search for laboratory and other variables that with certainty could contribute to the prediction of prognosis was unsuccessful. INTERPRETATION: Due to lack of safe prognostic predictors, all accidental hypothermic victims with circulatory failure should be rewarmed by cardiopulmonary bypass before further therapeutic decisions are made.

The reforming states group and the promotion of federalism.

Since 1991, leaders in health policy from the legislative and executive branches of state government have come together, with financial support and staff collaboration from the Milbank Memorial Fund, to share their experiences and to work on practical solutions to pressing health care problems. What began with a handful of states at the forefront of health reform is now the Reforming States Group (RSG), a bipartisan, voluntary association that includes leaders from over 40 states. This article describes the origins, history, and future prospects of the RSG.

Surgical treatment of spontaneous pneumothorax by wedge resection without pleurodesis or pleurectomy.

OBJECTIVE: Evaluation of wedge resection of the lung without pleurodesis or pleurectomy as a method of surgical treatment for spontaneous pneumothorax in terms of complications, recurrence rate and postoperative complaints. METHODS: Retrospective study of 132 operations for spontaneous pneumothorax in 120 patients (84 men and 36 women: mean age 34 years, range 14-77) performed between 1974 and 1993. The mean observation time was 84 months (range 6-229) and a 100% follow-up rate of all survivors (97%) was achieved. RESULTS: The indications for surgery were recurrent pneumothorax (52%), persisting air leak during first episode (45%), or hemothorax (3%). Perioperative findings were single bullous disease (86%), 2-3 bullae (6%), diffuse bullous disease (5%) and no bullous disease in 3% of the cases. The overall complication rate was 16% (30-day mortality 1%, reoperation for postoperative bleeding 2%, bronchopneumonia 8%, new pneumothorax during hospital stay 5%). The late recurrence rate (operated lung) was 5%. All recurrences were successfully treated by drainage (n = 3), exsufflation (n = 1) or observation only (n = 3). Reoperation was not necessary. Thirty-seven percent of the patients had postoperative complaints which they associated with the operation. CONCLUSION: Lung resection without pleurodesis or pleurectomy is a simple, safe and effective method of the surgical treatment of spontaneous pneumothorax in terms of complications and recurrence rate in patients with limited bullous disease.

[Antibiotic prevention and occurrence of wound infections in heart surgery and vascular surgery]. / Antibiotikaprofylakse og forekomst av sårinfeksjoner ved hjerte- og karkirurgi.

Post-operative wound infections are serious complications in cardiovascular surgery. In order to examine the routines for prophylactic antibiotics and frequency of wound infections, questionnaires were sent to heart and vascular surgery units in Norway. In heart surgery, the sternal wound infection rate registered during stay in hospital varied between 0-1.2%. Seven clinics used cephalothin prophylaxis and one cloxacillin and penicillin. One clinic added vancomycin in the case of valvular surgery. The duration of prophylaxis varied from six hours to four days. In vascular surgery, superficial wound infection rates of 1.5-4.0%, and deep infection rates of 0.8-2.0%, were reported. Seven clinics used cephalothin and three cefuroxime as prophylaxis. The duration of prophylaxis varied from one single dose to several days. In conclusion, the reported infection rates indicate that the antibiotic prophylaxis regimens used help to provide satisfactory protection against wound infections.

Dilation of the internal mammary artery by external papaverine application to the pedicle--an improved method.

Spasm of the internal mammary artery (IMA) during coronary bypass grafting may cause inadequate graft flow and makes accurate placement of sutures difficult. In addition, IMAs with poor intraoperative flow rates are more likely to occlude. In this study three methods for spasm prevention were compared in 51 patients undergoing coronary bypass surgery. In group 1, IMA pedicles were covered with a sponge soaked with papaverine solution (0.8 mg/ml of papaverine in 0.9% saline) and left intact distally, thus allowing continuous blood flow until used for bypass. In group 2, the IMAs were divided and clamped distally and the pedicle tucked into a papaverine-soaked sponge. In group 3, the IMAs were also divided distally, clamped, and placed under the upper sternum submerged in papaverine solution (0.8 mg/ml) inside a surgical glove. Free flow from the IMA was higher in group 3 than in groups 1 and 2 (60 ml/min vs. 44 and 30, respectively, P < 0.03). Morphometric measurements disclosed a larger luminal area and less folding of the internal elastic lamina in group 3 compared with groups 1 and 2 (0.73 mm2 vs 0.33 and 0.37, respectively, P < 0.03). Submersion in papaverine solution thus provides better procurement of IMA grafts than storage of the pedicle in a papaverine-soaked sponge.

[Deep accidental hypothermia with asystole. A successful treatment with heart-lung machine after prolonged cardiopulmonary resuscitation]. / Dyp aksidentell hypotermi med asystoli. Vellykket behandling med hjerte-lunge-maskin etter langvarig kardiopulmonal resuscitering.

Extracorporeal circulation can be utilized successfully to rewarm accidental hypothermia victims. This paper describes a 51 year-old man who had been immersed in cold sea water for about 45 minutes. At the time of rescue his ECG was isoelectric. The core temperature was 27 degrees C. Cardiopulmonary resuscitation was performed for 190 minutes before extracorporeal circulation was established. Without active surface rewarming the temperature had dropped to 24 degrees C. Biventricular heart failure became evident during rewarming. Sternotomy and pericardiotomy were carried out to exclude cardiac tamponade, which was not found. After two hours of reperfusion the patient could be weaned from bypass supported by high-dose vasopressor infusion. He was extubated the following day. He was discharged after 12 days without any signs of permanent damage to organs.

Accidental hypothermia with cardiac arrest: complete recovery after prolonged resuscitation and rewarming by extracorporeal circulation.

A 51-year-old male remained immersed in sea water (6 degrees C) for 40 min. Brought ashore, the ECG showed asystole. Advanced life support was immediately commenced. On arrival in hospital his rectal temperature was 27 degrees C, but continued to fall to 24 degrees C. The ECG remained isoelectric. Cardiopulmonary resuscitation was continued until extracorporeal circulation was established 190 min after rescue. Upon rewarming ventricular fibrillation occurred which was converted to sinus rhythm with a bolus of lignocaine followed by D.C. conversion at 31.5 degrees C. When rewarming was complete after 60 min, signs of severe heart failure became evident. Sternotomy and pericardiotomy were performed to exclude cardiac tamponade. After 60 min of re-perfusion the patient was be weaned from bypass supported by a high-dose vasopressor infusion and nitroglycerine. He was discharged after 13 days with no evidence of any permanent organ damage. Given the advantage of providing circulatory support, extracorporeal circulation may be useful when rewarming hypothermic victims with cardiac arrest.

Intensive home health care in the United States. Financing as technology.

This paper assesses the impact of mechanisms for financing intensive home health care services in the United States on their utilization. As lengths of stay have decreased in response to prospective payment methods for hospitals, demand has increased for intensive and complex services provided to patients in the home. Third-party payers, however, are willing to satisfy only some of this potential demand that their reimbursement policies have generated. It is the policies of payers rather than the safety and effectiveness of devices and procedures that are the major constraints on the expansion of intensive home health care. We describe the effects of these policies on who receives intensive home health care services, who provides them, what services are provided, how their quality is monitored, and what they cost.

Is reduced cardiac performance the only mechanism for myocardial infarct size reduction during beta adrenergic blockade?

Equal reductions in heart rate (44 beats X min-1) were obtained in cats by treatment with either the beta blocking agent timolol or alinidine, an agent claimed to cause bradycardia without interfering with beta adrenoceptor function. Infarct size was measured by staining with triphenyltetrazolium-chloride after 5 h of coronary occlusion and related to the area of hypoperfused myocardium as measured by autoradiography. Regional myocardial blood flow was measured by 15 micron radiolabelled microspheres. Compared with the control cats, in whom 87.4 (SEM 2.2)% of hypoperfused myocardium developed into necrosis, timolol reduced infarct size to 65.8 (SEM 2.6)% (p less than 0.001) and alinidine to 76.2 (SEM 3.1)% (p less than 0.01) of the hypoperfused area. Timolol reduced infarct size more than did alinidine (p less than 0.01). Necrosis was more extensive in the endocardium than in the epicardium in all groups. In the subendocardium timolol and alinidine reduced infarct size to the same extent, whereas timolol reduced infarct size more than alinidine in the subepicardium. Although heart rate proved to be the dominant haemodynamic predictor of infarct size, this study indicates that mechanisms other than reduced oxygen demand associated with bradycardia and cardiodepression are operating in the ischaemic myocardium during beta adrenergic blockade.

Does infarct size influence loss of embolised 15-micrometer microspheres from ischaemic myocardium?

The relationship between myocardial infarct size and loss of 15-micron microspheres from ischaemic tissue was investigated in anaesthetized cats. Radioactive microspheres were injected in the left atrium before and 5 h after left anterior descending coronary artery occlusion. Left ventricular hypoperfused zone (HZ) averaged 36.6% and infarct size (IS) 31.6%. Thus, 86% of HZ evolved into necrosis. Preocclusion blood flow was lower in ischaemic (1.62 ml/min per g) compared with non-ischaemic myocardium (2.09, p = 0.002), indicating 22% microsphere loss. In ischaemic subendocardium, oedema (3.7%) could account for the apparent loss. In ischaemic subepicardium, oedema was less pronounced and 18% physical sphere loss occurred. Subepicardial loss increased in proportion to IS and IS/HZ ratio (r2 = 0.71; p less than 0.005). Non-entrapment of 15-micron spheres in coronary circulation averaged 0.6%, and preocclusion spheres appeared in coronary sinus blood throughout the ischaemic period. In systemic circulation, non-entrapment during injection of preocclusion spheres was 7.8%, but only 1.8% 5 h later. Release of postocclusion spheres took place during KCl injection. Thus, myocardial ischaemia is associated with alterations in microvascular function allowing release of entrapped 15-micron spheres. Also, the magnitude of microsphere loss per gram tissue is related to infarct size.

Treating handicapped newborns: suggestions for institutional policy.

KIE: In October 1984 a conference of physicians and other health professionals, attorneys, members of the press, ethicists, and social scientists met at the State University of New York at Stony Brook to consider the medical, ethical, and social issues raised by the treatment of handicapped newborns. Presented here is a summary of guidelines for the implementation of their most important recommendation--the establishment of institutional policies concerning the internal decision making process regarding treatment and the procedures for sharing information about controversial cases with the public. The guidelines address the medical problems of diagnosis, prognosis, and clinical decision making; institutional responses to controversy within the institution and to the media and the public; and the composition and role of institutional review committees.^ieng

Myocardial blood flow conditions at re-perfusion following acute ischaemia.

The purpose of this study was to investigate the effect of re-perfusion upon distribution of radioactive microspheres in ischaemic myocardium. Ten anaesthetized cats were given 15-micron microspheres prior to left anterior coronary artery occlusion, at 1 h of occlusion, and after 1 h of subsequent re-perfusion. Pre-occlusion blood flow estimates were lower in tissue which had been ischaemic compared with nonischaemic regions in the same heart (1.44 versus 1.87 ml X min-1 X g-1, p less than 0.001), corresponding to 23% apparent loss. Loss also occurred in ischaemic right ventricular tissue (32%). In left ventricular ischaemic endocardium, apparent loss was due to development of oedema. Oedema was also significant in epicardial ischaemic tissue. Correction for oedema eliminated two-fifths of the loss, while three-fifths was due to physical loss. Oedema increased linearly with the level of re-perfusion. During re-perfusion, myocardial blood flow in previously ischaemic tissue was inhomogeneously distributed and, on average, 28% lower than in non-ischaemic myocardium. The 15-micron spheres appeared to pass through capillaries in the ischaemic subepicardium, but this process was not enhanced by reperfusion.

Measurement of local blood flow in acute myocardial infarction: loss of 15-micron microspheres during the first hour.

Distribution of radiolabelled microspheres is widely utilized for determination of regional blood flow in experimental myocardial infarction studies. The purpose of this investigation was evaluation of the microsphere method during 1 h of regional ischaemia. Special attention was focused upon loss of preocclusion microspheres from ischaemic myocardium; mechanisms for loss and blood flow distribution in non-ischaemic left ventricle. Microspheres (15 micron) were injected into the left atrium in nine pentobarbital anaesthetized cats prior to coronary artery occlusion and again after 1 h of occlusion. Preocclusion blood flow estimates were lower in ischaemic compared with non-ischaemic myocardium (1.36 vs. 1.62 cm3 X min-1 X g-1, P = 0.002), corresponding to 16% apparent loss. In endocardial ischaemic tissue, development of oedema could account for the loss. In epicardial ischaemic tissue, oedema was not present and loss was therefore due to migration of microspheres. Epicardial loss increased in proportion to restoration of left ventricular contractility. There was no evidence for significant microsphere loss through lymphatic pathways. In non-ischaemic left ventricular tissue, myocardial blood flow was evenly distributed from apex to base, and also between endocardial and epicardial layers. This study quantitates an important limitation to measurements of local blood flow in ischaemic myocardium by radiolabelled microspheres.