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Biomedical subjects

N H Cohen

Publications and source records attributed to N H Cohen.

35 records · Page 2Linked to original sources
PubMed1989

Postoperative pulse oximetry of patients in maxillomandibular fixation.

Following oral and maxillofacial surgery requiring maxillomandibular fixation (MMF), patients are at risk for respiratory problems that may result in decreased arterial oxygen saturation. As a pilot study, oxygen saturation was continuously monitored for 36 hours in 34 patients having 37 procedures requiring MMF. There were 28 hypoxic episodes in 12 patients. These observations emphasize the need for continuous respiratory monitoring during the postoperative period for patients in MMF, even when supplemental oxygen is used.

Adolescent↗
PubMed1989

Washin and washout of isoflurane administered via bubble oxygenators during hypothermic cardiopulmonary bypass.

Washin and washout of a volatile anesthetic given through the oxygenator during hypothermic (23.4 +/- 2.1 degrees C) cardiopulmonary bypass were studied in nine patients. The authors administered isoflurane and measured its partial pressure in arterial (Pa) and venous (Pv) blood and the gas exhausted from the oxygenator (PE) at 1, 2, 4, 8, 16, 32, and 48 min during washin. These measurements were repeated during washout, which coincided with rewarming. During washin, PE, Pa, and Pv progressively rose toward inlet gas partial pressure (PI). Equilibration of Pa with PI was 41% after 16 min, 51% after 32 min, and 57% after 48 min of washin. During washout, Pa declined to 24% of its peak after 16 min and to 13% after 32 min. Washin and washout were considerably slower in mixed venous blood. Washin of isoflurane appeared to occur more slowly during cardiopulmonary bypass than during administration via the lungs in normothermic patients, presumably because hypothermia increases tissue capacity, compensating for the effect of hemodilution that otherwise would decrease the blood/gas partition coefficient. During rewarming, washout appeared to occur as rapidly as from the lungs of normothermic patients. This may have resulted from the declining blood/gas partition coefficient (due to rewarming) and relatively limited tissue stores of isoflurane. The relationship between exhaust and arterial partial pressures was reasonably consistent; for clinical purposes, measurement of PE can be used to estimate Pa.

Cardiopulmonary Bypass↗
PubMed1989

Assessment of routine chest roentgenograms and the physical examination to confirm endotracheal tube position.

We consecutively and prospectively studied 219 critically ill patients to evaluate the accuracy of the physical examination in assessing ETT position and the appropriateness of taking routine chest x-ray films after intubation in the ICU. As a result of x-ray findings, 14 percent of the patients required ETT repositioning, and 5 percent had main-stem intubations. Endobronchial intubation was more common in females than in males, and frequently occurred after emergency intubations. Sixty percent of the main-stem intubations occurred despite the presence of equal breath sounds on examination. Techniques to minimize the risk of tube malposition, such as cuff ballottement in the suprasternal notch and referencing the ETT centimeter markings, were not completely reliable. This study confirms the unreliability of the physical examination to assess ETT position. Chest x-ray films after intubation are indicated to verify tube position, particularly after emergency intubations. Other techniques such as use of a lighted stylet require evaluation to determine whether they are more cost-effective in verifying ETT placement in patients who have no other indication for postintubation x-ray films.

Cost-Benefit Analysis↗
PubMed1989

Use of pulse oximetry in critically ill adults.

Pulse oximetry represents a major advance in noninvasive oxygenation monitoring in critically ill adults. Its technology has given practitioners a safe, accurate, and continuous method for assessing arterial oxygen saturation. A comprehensive understanding of the variables of oxygen transport and hypoxemia is essential to ensure correct data interpretation. The accuracy and clinical limitations of pulse oximeters and sensors are presented in this article. The clinical utility of pulse oximetry monitoring in critically ill adults is discussed, with consideration given to patient selection and specific procedures that incur hypoxemic risk. Issues of quality assurance and risk management that surround the use of pulse oximetry are addressed.

Critical Care↗
PubMed1988

In vitro anesthetic washin and washout via bubble oxygenators: influence of anesthetic solubility and rates of carrier gas inflow and pump blood flow.

The uptake and elimination of volatile anesthetic agents administered to patients under conditions of hemodilution and hypothermia during cardiopulmonary bypass have not been determined. To define the limitations imposed by oxygenators, we defined washin and washout curves for volatile anesthetic agents administered to bubble oxygenators primed with diluted blood (without connection to a patient). There was rapid equilibration of anesthetic partial pressure between delivered gas and blood (85-90% within 16 minutes). Increasing the gas inflow to the oxygenator from 3 to 12 L/min hastened washin and washout slightly, while increasing the pump blood flow from 3 to 5 L/min had no effect. Rates of washin and washout of anesthetics differed as a function of their blood/gas solubilities: enflurane greater than isoflurane greater than halothane during washin; isoflurane greater than enflurane greater than halothane during washout. However, these differences were small. Oxygenator exhaust partial pressures of anesthetic correlated with simultaneously obtained blood partial pressures, suggesting that monitoring exhaust gas may be useful clinically.

Anesthetics↗
PubMedDate not supplied

Ethical dilemmas about intensive care for patients with AIDS.

AIDS presents ethical dilemmas about intensive care. Even with intensive care the outcome for patients with AIDS is poor. Care givers have no ethical or medical obligation to provide futile care. Decisions concerning competent patients should be made jointly by physicians and the informed patients themselves. For incompetent patients decisions should be made jointly by physicians and appropriate patient-surrogates in light of the previously expressed wishes of the patients. Care givers should encourage patients with AIDS to express their preferences about life-sustaining treatment in order to avoid dilemmas should these patients later become incompetent. The AIDS epidemic may force more explicit discussions about the allocation of limited health-care resources, such as intensive care. Such allocation decisions should not discriminate against patients with AIDS.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Pancuronium reduces halothane requirement in man.

We studied the contribution of pancuronium to anesthetic requirement in man by comparing MAC for halothane alone in 18 patients, with that after intravenous administration of pancuronium, 0.1 mg/kg, in 17 patients. In each group, movement was observed in limbs isolated from the circulation by tourniquet. In patients receiving pancuronium, halothane MAC was 0.55%, whereas the control value was 0.73%. Thus pancuronium reduces halothane MAC by 25%.

Adult↗
PubMedDate not supplied

Cardiac rehabilitation in the coronary care unit. Part II.

The rehabilitation of the complicated-MI patient in the CCU should consist of early use of the bedside chair and progressive activity with the level and rate of advancement determined by frequent assessment of the clinical state. Patient education is an important part of the rehabilitation program, especially in the patient with complicated MI.

Coronary Care Units↗
PubMedDate not supplied

Carotid cross-over bypass. Cerebral revascularization after ligation of common carotid artery.

A rationale is presented for extra-anatomic carotid cross-over bypass to maintain or restore blood flow to the internal carotid artery distal to sites of disruption and ligation of a common carotid artery. Anatomic evidence indicates that the attachment of the carotid sheath to the hyoid bone is a barrier to spread of infection cephalad to that level. A patient with infected and disrupted right common carotid artery associated with an esophageal fistula was treated by double ligation of the artery. Contralateral hemiplegia 48 hours later forced consideration of cerebral revascularization. Left carotid angiography demonstrated patent cerebral vessels on the right, with retrograde filling of the right internal carotid artery to the bifurcation. These findings were interpreted as consistent with technical feasibility of external carotid to external carotid cross-over vein bypass in a suprahyoid location, avoiding reconstruction in an infected area and resulting in prompt recovery of function.

Brain↗