William Meadow

The effects of temperature and carbon dioxide breathing on ventilation and acid-base status of turtles

Abstract Respiratory minute volume (V e ) and oxygen consumption (V O 2 ) of freshwater turtles, Pseudemys scripta elegans , were measured at 10, 20 and 30 °C while the turtles breathed either air, 2, 4 or 6% CO 2 . In one series of animals arterial pH and P CO 2 , were measured as well and correlated with the ventilation. Inspired CO 2 caused hyperventilation which increased in proportion to either % inspired CO 2 or Pa CO 2 , and which reached about ten times the air-breathing ventilation when 6% CO 2 was breathed. The response was similar at each temperature. Ventilation (V e /V O 2 decreased with temperature with each breathing mixture, and, consequently, Pa CO 2 increased with temperature. The influence of temperature on the ventilatory control of Pa CO 2 when the turtles breathed air was the physiological mechanism responsible for the inverse relationship between blood pH and temperature.

End-of-Life After Birth: Death and Dying in a Neonatal Intensive Care Unit

Objective. In canonical modern bioethics, withholding and withdrawing medical interventions for dying patients are considered morally equivalent. However, electing not to administer cardiopulmonary resuscitation (CPR) struck us as easily distinguishable from withdrawing mechanical ventilation. Moreover, withdrawing mechanical ventilation from a moribund infant “feels” different from withdrawing mechanical ventilation from a hemodynamically stable child with a severe neurologic insult. Most previous descriptions of withdrawing and withholding intervention in the neonatal intensive care unit (NICU) have blurred many of these distinctions. We hypothesized that clarifying them would more accurately portray the process of end-of-life decision-making in the NICU. Methods. We reviewed the charts of all newborn infants who had birth weight >400 g and died in our hospital in 1988, 1993, and 1998 and extracted potential ethical issues (resuscitation, withdrawal, withholding, CPR, do-not-resuscitate orders, neurologic prognosis, ethics consult) surrounding each infants death. Results. Using traditional definitions, roughly half of all deaths in our NICU in 1993 and 1998 were associated with “withholding or withdrawing.” In addition, by 1998, >40% of our NICU deaths could be labeled “active withdrawal,” reflecting the extubation of infants regardless of their physiologic instability. This practice is growing over time. However, 2 important conclusions arise from our more richly elaborated descriptions of death in the NICU. First, when CPR was withheld, it most commonly occurred in the context of moribund infants who were already receiving ventilation and dopamine. Physiologically stable infants who were removed from mechanical ventilation for quality-of-life reasons accounted for only 3% of NICU deaths in 1988, 16% of NICU deaths in 1993, and 13% of NICU deaths in 1998. Moreover, virtually none of these active withdrawals took place in premature infants. Second, by 1998 infants, who died without CPR almost always had mechanical ventilation withdrawn. Finally, the median and average day of death for 100 nonsurvivors who received full intervention did not differ significantly from the 78 nonsurvivors for whom intervention was withheld. Conclusions. In our unit, a greater and greater percentage of doomed infants die without ever receiving chest compressions or epinephrine boluses. Rather, we have adopted a nuanced approach to withdrawing/withholding NICU intervention, providing what we hope is a humane approach to end-of-life decisions for doomed NICU infants. We suggest that ethical descriptions that reflect these nuances, distinguishing between withholding and withdrawing interventions from physiologically moribund infants or physiologically stable infants with morbid neurologic prognoses, provide a more accurate reflection of the circumstances of dying in the NICU.

Power and limitations of daily prognostications of death in the medical intensive care unit.

Objective:We tested the accuracy of predictions of impending death for medical intensive care unit patients, offered daily by their professional medical caretakers. Design:For 560 medical intensive care unit patients, on each medical intensive care unit day, we asked their attending physicians, fellows, residents, and registered nurses one question: “Do you think this patient will die in the hospital or survive to be discharged?” Results:We obtained >6,000 predictions on 2018 medical intensive care unit patient days. Seventy-five percent of MICU patients who stayed ≥4 days had discordant predictions; that is, at least one caretaker predicted survival, whereas others predicted death before discharge. Only 107 of 206 (52%) patients with a prediction of “death before discharge” actually died in hospital. This number rose to 66% (96 of 145) for patients with 1 day of corroborated (i.e., >1) prediction of “death,” and to 84% (79 of 94) with at least 1 unanimous day of predictions of death. However, although positive predictive value rose with increasingly stringent prediction criteria, sensitivity fell so that the area under the receiver-operator characteristic curve did not differ for single, corroborated, or unanimous predictions of death. Subsets of older (>65 yrs) and ventilated medical intensive care unit patients revealed parallel findings. Conclusions:1) Roughly half of all medical intensive care unit patients predicted to die in hospital survived to discharge nonetheless. 2) More highly corroborated predictions had better predictive value; although, approximately 15% of patients survived unexpectedly, even when predicted to die by all medical caretakers.

Just, in Time: Ethical Implications of Serial Predictions of Death and Morbidity for Ventilated Premature Infants

OBJECTIVES. For a cohort of extremely premature, ventilated, newborn infants, we determined the power of either serial caretaker intuitions of “die before discharge” or serial illness severity scores to predict the outcomes of death in the NICU or neurologic performance at corrected age of 2 years. METHODS. We identified 268 premature infants who were admitted to our NICU in 1999–2004 and required mechanical ventilation. For each infant on each day of mechanical ventilation, we asked nurses, residents, fellows, and attending physicians the following question: “Do you think this child is going to live to go home or die before hospital discharge?” In addition, we calculated illness severity scores until either death or extubation. RESULTS. A total of 17066 intuition profiles were obtained on 5609 days of mechanical ventilation in the NICU. One hundred (37%) of 268 profiled infants had ≥1 intuition of die before discharge. Only 33 infants (33%) with an intuition of die actually died in the NICU. Of 48 infants with even 1 day of corroborated intuition of die in the NICU, only 7 (14%) were alive with both Mental Developmental Index and Psychomotor Developmental Index scores of >69, and only 2 (4%) were alive with both Mental Developmental Index and Psychomotor Developmental Index Scores of >79 at corrected age of 2 years. On day of life 1, the Score for Neonatal Acute Physiology II value for nonsurvivors (38.2 ± 18.1) was significantly higher than that for survivors (26.3 ± 12.7). However, this difference decreased steadily over time as scores improved for both groups. CONCLUSIONS. Illness severity scores become progressively less helpful over time in distinguishing infants who will either die in the NICU or survive with low Mental Developmental Index/Psychomotor Developmental Index scores. Serial caretaker intuitions of die before discharge also fail to identify prospective nonsurviving infants. However, corroborated intuitions of die before discharge identify a subset of infants whose likelihood of surviving to 2 years with both MDI and PDI >80 is approximately 4%.

Use of vasopressin in refractory hypotension in children with vasodilatory shock: five cases and a review of the literature.

This article describes case studies of five children treated with vasopressin for refractory hypotension. In addition, physiology and pharmacology of vasopressin are reviewed in a comprehensive survey of the literature from 1966 until the present. In all five children, blood pressure increased immediately after vasopressin administration. The preliminary success of vasopressin for hypotension the setting of vasodilatory shock is promising. This limited use of vasopressin in the setting of refractory hypotension in these patients appears to be safe; the appropriate patient population and dose regimen are not yet determined.

The OHRP and SUPPORT

A group of medical ethicists and pediatricians asks for reconsideration of the recent Office for Human Research Protections decision about informed consent in SUPPORT.

Whom are we comforting? An analysis of comfort medications delivered to dying neonates.

OBJECTIVES To clarify the use of end-of-life comfort medications or neuromuscular blockers (NMBs) in culturally different neonatal intensive care units (NICUs). STUDY DESIGN Review of medical files of newborns > 22 weeks gestation who died in the delivery room or the NICU during 12 months in four NICUs (Chicago, Milwaukee, Montreal, and Groningen). We compared use of end-of-life comfort medications and NMBs. RESULTS None of the babies who died in the delivery room received comfort medications. The use of opiods (77%) or benzodiazepines (41%) around death was similar in all NICUs. Increasing this medication around extubation occurred most often in Montreal, rarely in Milwaukee and Groningen, and never in Chicago. Comfort medications use had no significant impact on the time between extubation and death. NMBs were never used around death in Chicago, once in Montreal, and more frequently in Milwaukee and Groningen. Initiation of NMB after extubation occurred only in Groningen. CONCLUSION Comfort medications were administered to almost all dying infants in each NICU. Some, but not all, centers were comfortable increasing these medications around or after extubation. In three centers, NMBs were at times present at the time of death. However, only in Holland were NMBs initiated after extubation.

Marketing Fast Food: Impact of Fast Food Restaurants in Children’s Hospitals

OBJECTIVES. The objectives of this study were (1) to determine fast food restaurant prevalence in hospitals with pediatric residencies and (2) to evaluate how hospital environment affects purchase and perception of fast food. METHODS. We first surveyed pediatric residency programs regarding fast food restaurants in their hospitals to determine the prevalence of fast food restaurants in these hospitals. We then surveyed adults with children after pediatric outpatient visits at 3 hospitals: hospital M with an on-site McDonald’s restaurant, hospital R without McDonald’s on site but with McDonald’s branding, and hospital X with neither on-site McDonald’s nor branding. We sought to determine attitudes toward, consumption of, and influences on purchase of fast food and McDonald’s food. RESULTS. Fifty-nine of 200 hospitals with pediatric residencies had fast food restaurants. A total of 386 outpatient surveys were analyzed. Fast food consumption on the survey day was most common among hospital M respondents (56%; hospital R: 29%; hospital X: 33%), as was the purchase of McDonald’s food (hospital M: 53%; hospital R: 14%; hospital X: 22%). McDonald’s accounted for 95% of fast food consumed by hospital M respondents, and 83% of them bought their food at the on-site McDonald’s. Using logistic regression analysis, hospital M respondents were 4 times more likely than respondents at the other hospitals to have purchased McDonald’s food on the survey day. Visitors to hospitals M and R were more likely than those at hospital X to believe that McDonald’s supported the hospital financially. Respondents at hospital M rated McDonald’s food healthier than did respondents at the other hospitals. CONCLUSIONS. Fast food restaurants are fairly common in hospitals that sponsor pediatric residency programs. A McDonald’s restaurant in a children’s hospital was associated with significantly increased purchase of McDonald’s food by outpatients, belief that the McDonald’s Corporation supported the hospital financially, and higher rating of the healthiness of McDonald’s food.

Should the “Slow Code” Be Resuscitated?

Most bioethicists and professional medical societies condemn the practice of “slow codes.” The American College of Physicians ethics manual states, “Because it is deceptive, physicians or nurses should not perform half-hearted resuscitation efforts (‘slow codes’).” A leading textbook calls slow codes “dishonest, crass dissimulation, and unethical.” A medical sociologist describes them as “deplorable, dishonest and inconsistent with established ethical principles.” Nevertheless, we believe that slow codes may be appropriate and ethically defensible in situations in which cardiopulmonary resuscitation (CPR) is likely to be ineffective, the family decision makers understand and accept that death is inevitable, and those family members cannot bring themselves to consent or even assent to a do-not-resuscitate (DNR) order. In such cases, we argue, physicians may best serve both the patient and the family by having a carefully ambiguous discussion about end-of-life options and then providing resuscitation efforts that are less vigorous or prolonged than usual.

Acute hemodynamic effects of caffeine administration in premature infants

Objective:Administration of caffeine citrate (caffeine) has been a central component of the treatment of apnea of prematurity. However, given its multiple pharmacologic effects, caffeine might be expected to produce hemodynamic changes in heart rate, stroke volume, cardiac output and vascular resistance.Study Design:In this prospective observational study, we report the hemodynamic effects of intravenous caffeine administration in a population of premature infants who received caffeine to correct or prevent apnea of prematurity.Methods:Hemodynamic effects of caffeine were determined in 31 infants. Stroke volume was measured via echocardiogram, using velocity time integral at the aortic root diameter. Statistically univariate analyses were performed parametrically using paired t-test and nonparametrically (sign test). Multivariate linear regression models were used to identify subgroup covariate effects.Results:After intravenous caffeine, cardiac index increased in 31 of 31 trials, by an average of 14.6±16.3% (s.d.); stroke volume increased in 24 of 31 trials, by 7.8±12.2%; heart rate increased in 28 of 31 trials by 7.7±7.2 beats per min; and blood pressure increased in 25 of 31 trials, by 4.1±5.8 mm Hg (all P<0.001). Multivariate linear regression revealed no significant effect of dose, birth weight, gestational age or postnatal age.Conclusions:Intravenous caffeine consistently increases cardiac output and blood pressure in relatively stable premature infants, when given to treat or prevent apnea of prematurity. We speculate that there may be a role for caffeine in the hemodynamic treatment of hypotensive/hypoperfused infants.