Effect of routine administration of analgesia on energy expenditure in critically ill patients

Current Perspectives on the Assessment and Management of Pain in the Intensive Care Unit

Critical illness is often painful, both from the underlying source of illness, as well as necessary procedures performed for the monitoring and care of these patients. Pain is often under-recognized in the critically ill, especially among those who cannot self-report, so accurate assessment and management continue to be major consideration in their care. Pain management in the intensive care unit (ICU) is an evolving practice, with a focus on accurate and frequent pain assessment, and targeted pharmacologic and non-pharmacologic treatment methods to maximize analgesia and minimize sedation. In this review, we will evaluate several validated methods of pain assessment in the ICU and present management options. We will review the evidence-based recommendations put forth by the largest critical care societies and several high-quality studies related to both the in-hospital approach to pain, as well as the short- and long-term consequences of untreated pain in ICU patients. We conclude with future directions.

Stroke in critical COVID-19 patients: a cautionary tale from the frontlines

Introduction

Although Coronavirus Disease 2019 (COVID-19) is primarily a disease of the respiratory system in its transmission and clinical manifestations, physicians have also reported a tropism toward the nervous system.

Methods

Neurological symptoms can occur as one of many systemic manifestations of a critical form of the disease or in isolation as the predominant presenting complaint.

Results

We report a series of 6 patients who suffered significant cerebrovascular accidents while being treated for critical COVID-19 in the intensive care units of a quaternary care hospital in New York’s Hudson valley.

Conclusions

This series demonstrates how a relatively rare but catastrophic neurological complication can occur in patients with COVID-19 while they are being managed for their more common problems such as respiratory and renal failure.

Systematic review of factors associated with energy expenditure in the critically ill

BACKGROUND AND AIMS

Indirect calorimetry is the reference standard for energy expenditure measurement. Predictive formulae that replace it are inaccurate. Our aim was to review the patient and clinical factors associated with energy expenditure in critically ill patients.

METHODS

We conducted a systematic review of the literature. Eligible studies were those reporting an evaluation of factors and energy expenditure. Energy expenditure and factor associations with p-values were extracted from each study, and each factor was classified as either significantly, indeterminantly, or not associated with energy expenditure. Regression coefficients were summarized as measures of central tendency and spread. Metanalysis was performed on correlations.

RESULTS

The search strategy yielded 8521 unique articles, 307 underwent full text review, and 103 articles were included. Most studies were in adults. There were 95 factors with 352 evaluations. Minute volume, weight, age, % body surface area burn, sedation, post burn day, and caloric intake were significantly associated with energy expenditure. Heart rate, fraction of inspired oxygen, respiratory rate, respiratory disease diagnosis, positive end expiratory pressure, intensive care unit days, C- reactive protein, and size were not associated with energy expenditure. Multiple factors (n = 37) were identified with an unclear relationship with energy expenditure and require further evaluation.

CONCLUSIONS

An important interval step in the development of accurate formulae for energy expenditure estimation is a better understanding of relationships between patient and clinical factors and energy expenditure. The review highlights the limitations of currently available data, and identifies important factors that are not included in current prediction formulae of the critically ill.

Acute Respiratory Distress Syndrome: Etiology, Pathogenesis, and Summary on Management

The acute respiratory distress syndrome (ARDS) has multiple causes and is characterized by acute lung inflammation and increased pulmonary vascular permeability, leading to hypoxemic respiratory failure and bilateral pulmonary radiographic opacities. The acute respiratory distress syndrome is associated with substantial morbidity and mortality, and effective treatment strategies are limited. This review presents the current state of the literature regarding the etiology, pathogenesis, and management strategies for ARDS.

Role of Nutrition Support in Inflammatory Conditions

This review intends to summarize recent development on the potential nutrition implications of acute inflammation encountered during critical illness. Different aspects of the inflammatory response and their impact on nutrition management during critical illness will be discussed: the timing of the postinjury metabolic response, the integration of regulatory mechanisms involved in the metabolic response to stress, the oxidative stress, the metabolic and clinical consequences in terms of energy expenditure, use of energy, changes in body composition, and behavior.

Management of Pain in the Critically Ill

Analgesia for critically ill patients can be provided most effectively by the use of modern techniques. Under standing of the anatomical pathways for nociceptive sig nal transmission allows the use of techniques that mod ulate or block nociceptive information at several levels (periphery, spinal cord, and systemic). A comprehen sive discussion of analgesic techniques at each level is presented. Formulation of a treatment plan is discussed. Several examples are presented to show the decision- making process for the use of modern analgesic tech niques in critically ill patients.

Influence of inhalation injury on energy expenditure in severely burned children

OBJECTIVE

Determine the effect of inhalation injury on burn-induced hypermetabolism in children.

DESIGN

Prospective study comparing hypermetabolism (i.e., resting energy expenditure and oxygen consumption) in burned children with and without inhalation injury during acute hospitalization.

SETTING

Single pediatric burn center.

PATIENTS

Eighty-six children (1-18 years) with ≥40% total body surface area burns were stratified to two groups: no inhalation injury and inhalation injury.

INTERVENTIONS

None.

MAIN MEASUREMENTS AND RESULTS

Inhalation injury was diagnosed based on bronchoscopic evaluation. At admission, PaO2:FiO2 ratios (an index of respiratory distress) were significantly higher in patients with no inhalation injury than in patients with inhalation injury. No differences were detected in resting energy expenditure or percent of the predicted basal metabolic rate between groups. Additionally, oxygen consumption did not significantly differ between groups.

CONCLUSIONS

Inhalation injury does not augment the burn-induced hypermetabolic stress response in children, as reflected by resting energy expenditure and oxygen consumption.

Palliative care in the ICU: relief of pain, dyspnea, and thirst--a report from the IPAL-ICU Advisory Board

PURPOSE

Pain, dyspnea, and thirst are three of the most prevalent, intense, and distressing symptoms of intensive care unit (ICU) patients. In this report, the interdisciplinary Advisory Board of the Improving Palliative Care in the ICU (IPAL-ICU) Project brings together expertise in both critical care and palliative care along with current information to address challenges in assessment and management.

METHODS

We conducted a comprehensive review of literature focusing on intensive care and palliative care research related to palliation of pain, dyspnea, and thirst.

RESULTS

Evidence-based methods to assess pain are the enlarged 0-10 Numeric Rating Scale (NRS) for ICU patients able to self-report and the Critical Care Pain Observation Tool or Behavior Pain Scale for patients who cannot report symptoms verbally or non-verbally. The Respiratory Distress Observation Scale is the only known behavioral scale for assessment of dyspnea, and thirst is evaluated by patient self-report using an 0-10 NRS. Opioids remain the mainstay for pain management, and all available intravenous opioids, when titrated to similar pain intensity end points, are equally effective. Dyspnea is treated (with or without invasive or noninvasive mechanical ventilation) by optimizing the underlying etiological condition, patient positioning and, sometimes, supplemental oxygen. Several oral interventions are recommended to alleviate thirst. Systematized improvement efforts addressing symptom management and assessment can be implemented in ICUs.

CONCLUSIONS

Relief of symptom distress is a key component of critical care for all ICU patients, regardless of condition or prognosis. Evidence-based approaches for assessment and treatment together with well-designed work systems can help ensure comfort and related favorable outcomes for the critically ill.

Hypocaloric considerations in patients with potentially hypometabolic disease States

The provision of nutrition has traditionally been driven by the desire to provide adequate calories. However, over the past decade it has become evident that provision of excess calories can be detrimental to patients' outcomes in both critical care and long-term care settings. This review examines patient populations for whom hypocaloric nutrition can be both appropriate and beneficial. In specific situations, critically ill patients, such as those with obesity, stroke, and spinal cord injury, may have decreased energy requirements. In patients with spinal cord injury, the level of injury significantly correlates with the extent of reduced caloric energy expenditure. Ventilator-dependent patients with amyotrophic lateral sclerosis (ALS) have decreased energy needs; energy expenditure for ALS patients is lower than the predictive equation value. Aging patients will have decreased energy needs relative to a reduction in lean body mass. Patients with cerebral palsy (CP) have significantly lower caloric requirements than anticipated using predictive equations. Patients with CP pose a particular challenge in nutrition assessment. Several studies demonstrate that patients with CP have significantly lower caloric requirements than anticipated using predictive equations; thus, patients with CP benefit from indirect calorimetry. Provision of nutrition for obese patients is briefly addressed, as this is an increasingly important consideration for nutrition support in both the critical care and long-term care settings. When indirect calorimetry is not available, clinicians should remember that most patients will have low resting energy expenditure regardless of functional status and require frequent evaluation during institution of nutrition recommendations to guard against overfeeding and obesity.

Increased energy expenditure and glucose oxidation during acute nontraumatic skin pain in humans

BACKGROUND AND OBJECTIVE

Tissue injury is accompanied by pain and results in increased energy expenditure, which may promote catabolism. The extent to which pain contributes to this sequence of events is not known.

METHODS

In a cross-over design, 10 healthy volunteers were examined on three occasions; first, during self-controlled nontraumatic electrical painful stimulus to the abdominal skin, maintaining an intensity of 8 on the visual analogue scale (0-10). Next, the electrical stimulus was reproduced during local analgesia and, finally, there was a control session without stimulus. Indirect calorimetry and blood and urine sampling was done in order to calculate energy expenditure and substrate utilization.

RESULTS

During pain stimulus, energy expenditure increased acutely and reversibly by 62% (95% confidence interval, 43-83), which was abolished by local analgesia. Energy expenditure paralleled both heart rate and blood catecholamine levels. The energy expenditure increase was fuelled by all energy sources, with the largest increase in glucose utilization.

CONCLUSION

The pain-related increase in energy expenditure was possibly mediated by adrenergic activity and was probably to a large extent due to increased muscle tone. These effects may be enhanced by cortical events related to the pain. The increase in glucose consumption favours catabolism. Our findings emphasize the clinical importance of pain management.

[Effects of sedative agents on metabolic demand]

Literature about the effects of sedative drugs on the metabolic demand of critically ill patients is relatively old and of relatively poor quality. Most are experimental or observational studies. Level of evidence is therefore relatively low corresponding to "expert opinion". The effects of analgesics and hypnotics on tissue metabolic demand associated remain difficult to be adequately quantified. They are essentially related to a decreased neuro-humoral response to stress. This response involves principally the sympathetic system, which could be effectively blocked by most of the anesthetic agents. Other factors could participate to the observed reduction in tissue metabolic demand, as a decrease in spontaneous muscular activity, a reduction in work of breathing and/or a decrease in body temperature. The relative contribution of these different factors will depend on the clinical situation of the patient. Proper effects of anesthetic agents on cellular metabolism are limited as they can only decrease the functional component of this metabolism especially at the level of the heart and to some extent, at the level of the brain. Although the control of the sympathetic activity may be beneficial in critically ill patient, complete sympathetic blockade could be detrimental. Indeed, when oxygen transport to the tissues is acutely reduced, the sympathetic system plays an important role in the redistribution of blood flow according of local metabolic demand. The complete blunting of the neuro-humoral response to stress and therefore of the sympathetic system alters this physiological mechanism and results in a decrease in tissue oxygen extraction capabilities. An imbalance between tissue oxygen demand and delivery could appear with the development of cellular hypoxia. The institution of sedation in a critically ill patient requires careful evaluation of the sedation level using an appropriate scale. In patients in whom a reduction in metabolic demand is specifically requested, but also in patients with limited oxygen transport, the effects of sedative agents on the oxygen consumption-oxygen delivery relationship must also be monitored. The choice of the different agents to be administered will depend on the predefined objectives. As far as intravenous agents are concerned, there is no evidence than one association is more efficient in reducing patient's metabolic demand.

Assessment, physiological monitoring, and consequences of inadequately treated acute pain

Postoperative pain is a major health care issue. Several factors have contributed to inadequate postoperative pain control, including a lack of understanding of preemptive pain management strategies, mistaken beliefs and expectations of patients, inconsistencies in pain assessment practices, use of as-needed analgesics that patients must request, and lack of analgesic regimens that account for interindividual differences and requirements. Untreated acute pain has the potential to produce acute neurohumoral changes, neuronal remodeling, and long-lasting psychologic and emotional distress and may lead to prolonged chronic pain states. To effectively manage postoperative pain, nurses must be able to adequately assess pain severity in diverse patient populations, understand how to monitor physiologic changes associated with pain and its treatment, be prepared to address the psychosocial experiences accompanying pain, and know the consequences of inadequate analgesia. It is important for nurses to be aware of relevant research and evidence-based guidelines that are available to guide pain assessments and patient monitoring practices.

Assessment, physiological monitoring, and consequences of inadequately treated acute pain

Postoperative pain is a major health care issue. Several factors have contributed to inadequate postoperative pain control, including a lack of understanding of preemptive pain management strategies, mistaken beliefs and expectations of patients, inconsistencies in pain assessment practices, use of as-needed analgesics that patients must request, and lack of analgesic regimens that account for inter-individual differences and requirements. Untreated acute pain has the potential to produce acute neurohumoral changes, neuronal remodeling, and long-lasting psychological and emotional distress, and may lead to prolonged chronic pain states. To effectively manage postoperative pain, nurses must be able to adequately assess pain severity in diverse patient populations, understand how to monitor physiological changes associated with pain and its treatment, be prepared to address the psychosocial experiences accompanying pain, and know the consequences of inadequate analgesia. It is important for nurses to be aware of relevant research and evidence-based guidelines that are available to guide pain assessments and patient-monitoring practices.

Palliative Care Consultation, Quality-of-Life Measurements, and Bereavement for End-of-Life Care in Patients With Lung Cancer

OBJECTIVE

To develop clinical practice guidelines for application of palliative care consultation, quality-of-life measurements, and appropriate bereavement activities for patients with lung cancer.

METHODS

To review the pertinent medical literature on palliative care consultation, quality-of-life measurements, and bereavement for patients with lung cancer, developing multidisciplinary discussions with authorities in these areas, and evolving written guidelines for end-of-life care of these patients.

RESULTS

Palliative care consultation has developed into a new specialty with credentialing of experts in this field based on extensive experience with patients in end-of-life circumstances including those with lung cancer. Bereavement studies of the physical and emotional morbidity of family members and caregivers before, during, and after the death of a cancer patient have supported truthful communication, consideration of psychological problems, effective palliative care, understanding of the patient's spiritual and cultural background, and sufficient forewarning of impending death.

CONCLUSION

Multidisciplinary investigations and experiences, with emphasis on consultation and delivery of palliative care, timely use of quality-of-life measurements for morbidities of treatment modalities and prognosis, and an understanding of the multifaceted complexities of the bereavement process, have clarified additional responsibilities of the attending physician.

Resting energy expenditure during mechanical ventilation and its relationship with the type of lesion

BACKGROUND

Resting energy expenditure (REE) of critically ill patients is usually calculated according to basal energy expenditure obtained from Harris-Benedict equations traditionally corrected by different stress factors, resulting in a variable accuracy for the individual patient. The objective of this study was to investigate whether or not the type of lesion affects the metabolism level of critically ill patients treated with mechanical ventilation. We performed a retrospective study measuring the REE of critically ill patients with 3 different types of lesions (trauma, medical, surgical) who were treated with mechanical ventilation and sedation. Each lesion group of patients was matched with another group, differing in the type of lesion, according to gender, age, and weight.

METHODS

Eighty-seven from a database of 175 critically ill patients undergoing indirect calorimetry were necessary for matching. Twenty matched pairs of patients for each of the following different type of lesion were obtained: medical vs surgical, medical vs trauma, and surgical vs trauma.

RESULTS

The mean REE difference was 52 kcal/d (95% confidence interval [CI] of -136 -241 kcal/d) for the medical vs surgical group, 5 kcal/d (95% CI -236 -247 kcal/d) for the medical vs trauma group and 43 kcal/d (95% CI of -132-219 kcal/d) for the surgical vs trauma group. No statistically significant differences between groups were found in the measured REE. We did not find statistically significant differences in the measured REE of patients with and without infection.

CONCLUSIONS

Critically ill patients with different types of lesion treated with mechanical ventilation have similar measured REE.

Comparison of the standard predictive equation for calculation of resting energy expenditure with indirect calorimetry in hospitalized and healthy dogs

OBJECTIVE

To determine the level of clinical agreement between 2 methods for the measurement of resting energy expenditure (REE).

DESIGN

Prospective case series.

ANIMALS

77 dogs.

PROCEDURE

Oxygen consumption (Vo2) and CO2 production (Vco2) were measured with an open-flow indirect calorimeter in healthy (n = 10) and ill (67) dogs. Measurements were collected at 3 time periods on 2 days. The Vo2 and the Vco2 measurements were then used to calculate the REE values.

RESULTS

Mean values of measured (MREE) and predicted (PREE) REEs in healthy dogs and a dog with medical illnesses or trauma were not significantly different. There was a significant difference on day 2 between the MREE and PREE in the group of dogs recovering from major surgery. More importantly, there was significant variation between the PREE and MREE on an individual-dog basis. The PREE only agreed to within +/- 20% of the MREE in 51% to 57% of the dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

The level of agreement between these two methods for determining the 24-hour REE was poor in individual dogs. The level of disagreement between the 2 methods indicates that these methods may not be used interchangeably in a clinical setting. Measurement of REE by use of indirect calorimetry may be the only reliable method of determining REE in an individual ill or healthy dog.

The symptom burden of chronic critical illness

OBJECTIVE

To assess self-reported symptom burden of chronic critical illness.

DESIGN

Prospective cohort study.

SETTING

Respiratory care unit for treatment of chronically critically ill patients at an academic, tertiary-care, urban medical center.

PATIENTS

Fifty patients who underwent elective tracheotomy and transfer from an adult intensive care unit to the respiratory care unit for weaning from mechanical ventilation.

INTERVENTIONS

Assessment of physical and psychological symptoms through patients' self-reports using a modification of the Condensed Form of the Memorial Symptom Assessment Scale.

MEASUREMENTS AND MAIN RESULTS

We measured self-reported symptom burden, ventilator outcomes, and vital status and functional status at discharge and 3 and 6 months after discharge. Half of the patients were successfully liberated from mechanical ventilation, but most hospital survivors were discharged to skilled nursing facilities and more than half of the cohort was dead at 3 months after discharge. Seventy-two percent (36 of 50) of patients were able to self-report symptoms during the period of respiratory care unit treatment. Among patients responding to symptom assessment, approximately 90% were symptomatic. Forty-four percent of patients reported pain at the highest levels. More than 60% reported psychological symptoms at these levels, and approximately 90% of patients reported severe distress due to difficulty communicating.

CONCLUSIONS

Physical and psychological symptom distress is common and severe among patients receiving treatment for chronic critical illness. The majority of these patients die soon after hospital discharge. Given the level of distress in our study patients and the high mortality rate that we and others have observed, greater attention should be given to relief of pain and other distressing symptoms and to assessment of burdens and benefits of treatment for the chronically critically ill.

Narcotic and benzodiazepine use after withdrawal of life support: association with time to death?

OBJECTIVE

To determine whether the dose of narcotics and benzodiazepines is associated with length of time from mechanical ventilation withdrawal to death in the setting of withdrawal of life-sustaining treatment in the ICU.

DESIGN

Retrospective chart review.

SETTING

University-affiliated, level I trauma center.

PATIENTS

Consecutive critically ill patients who had mechanical ventilation withdrawn and subsequently died in the ICU during two study time periods.

RESULTS

There were 75 eligible patients with a mean age of 59 years. The primary ICU admission diagnoses included intracranial hemorrhage (37%), trauma (27%), acute respiratory failure (27%), and acute renal failure (20%). Patients died during a median of 35 min (range, 1 to 890 min) after ventilator withdrawal. On average, 16.2 mg/h opiates in morphine equivalents and 7.5 mg/h benzodiazepine in lorazepam equivalents were administered during the time period starting 1 h before ventilator withdrawal and ending at death. There was no statistically significant relationship between the average hourly narcotic and benzodiazepine use during the 1-h period prior to ventilator withdrawal until death, and the time from ventilator withdrawal to death. The restriction of medication assessment in the last 2 h of life showed an inverse association between the use of benzodiazepines and time to death. For every 1 mg/h increase in benzodiazepine use, time to death was increased by 13 min (p = 0.015). There was no relationship between narcotic dose and time to death during the last 2 h of life (p = 0.11).

CONCLUSIONS

We found no evidence that the use of narcotics or benzodiazepines to treat discomfort after the withdrawal of life support hastens death in critically ill patients at our center. Clinicians should strive to control patient symptoms in this setting and should document the rationale for escalating drug doses.

Assessment of resting energy expenditure in mechanically ventilated patients

BACKGROUND

Usual equations for predicting resting energy expenditure (REE) are not appropriate for critically ill patients, and indirect calorimetry criteria render its routine use difficult.

OBJECTIVE

Variables that might influence the REE of mechanically ventilated patients were evaluated to establish a predictive relation between these variables and REE.

DESIGN

The REE of 70 metabolically stable, mechanically ventilated patients was prospectively measured by indirect calorimetry and calculated with the use of standard predictive models (Harris and Benedict's equations corrected for hypermetabolism factors). Patient data that might influence REE were assessed, and multivariate analysis was conducted to determine the relations between measured REE and these data. Measured and calculated REE were compared by using the Bland-Altman method.

RESULTS

Multivariate analysis retained 4 independent variables defining REE: body weight (r(2) = 0.14, P < 0.0001), height (r(2) = 0.11, P = 0.0002), minute ventilation (r(2) = 0.04, P = 0.01), and body temperature (r(2) = 0.07, P = 0.002): REE (kcal/d) = 8 x body weight + 14 x height + 32 x minute ventilation + 94 x body temperature - 4834. REE calculated with this equation was well correlated with measured REE (r(2) = 0.61, P < 0.0001). Bland-Altman plots showed a mean bias approaching zero, and the limits of agreement between measured and predicted REE were clinically acceptable.

CONCLUSION

Our results suggest that REE estimated on the basis of body weight, height, minute ventilation, and body temperature is clinically more relevant than are the usual predictive equations for metabolically stable, mechanically ventilated patients.

Palliative care of the chronically critically ill patient

Evidence is accumulating that distressing physical and emotional symptoms are prevalent among patients with critical illness, including those requiring prolonged mechanical ventilation, and that suffering is underestimated and undertreated by caregivers. Although patients and their families rank communication as a preeminent concern, it remains deficient in process and content, even when the illness requires weeks of critical care. Strategies are available to improve symptom management and communication about appropriate goals of care. For the CCI, whose risks of death, disability, and suffering are so high, it is essential that excellent palliative care be provided along with restorative treatment in an integrated way.

Energy expenditure and intake in children with sickle cell disease during acute illness

BACKGROUND

Children with sickle cell disease have frequent bouts of pain and infection which may increase energy expenditure, decrease energy intake and lead to a subsequent energy deficit.

METHODS

Two groups of African-American children with sickle cell disease-SS genotype were enrolled in this study upon hospital admission for a sickle cell disease related illness: a younger (<6 years, n=14, 7 M) and older group (> or =6 years, n=17, 8 M). Body composition and dietary intake were assessed, and sleeping (younger) or resting energy expenditure (older) were measured by indirect calorimetry at admission and one month later at steady state.

RESULTS

Energy expenditure was not different between the two timepoints for younger children, but was slightly elevated at steady state (+50 kcal/d, P=0.049) in the older group. After controlling for gender, changes in fat-free mass and dietary intake, the significance disappeared. Energy intake in both groups was significantly depressed at admission compared to follow-up (P<0.01).

CONCLUSIONS

These children and adolescents did not expend excess energy during their acute illness, however, an energy deficit was observed secondary to poor energy intake. Since 20% of patients with sickle cell disease have multiple hospitalizations per year, these results provide justification for the development and evaluation of nutrition care protocols to maintain adequate caloric intake during hospitalization and recovery.

End-of-life care in the intensive care unit: where are we now?

A growing body of evidence and experience has effaced what were once thought to be clear distinctions between "critical illness" and "terminal illness" and has exposed the problems of postponing palliative care for intensive care patients until death is obviously imminent. Integration of palliative care as a component of comprehensive intensive care is now seen as more appropriate for all critically ill patients, including those pursuing aggressive treatments to prolong life. At present, however, data on which to base practice in this integrated model remain insufficient, and forces of the healthcare economy and other factors may constrain its application. The purpose of this article is to map where we are now in seeking to improve palliative care in the intensive care unit. We review existing evidence, which suggests that both symptom management and communication about preferences and goals of care warrant improvement and that prevailing practices for limitation of life-sustaining treatments are inconsistent and possibly irrational. We also address the need for assessment tools for research and quality improvement. We discuss recent initiatives and ongoing obstacles. Finally, we identify areas for further exploration and suggest guiding principles.

Effect of neuromuscular blockade on oxygen consumption and energy expenditure in sedated, mechanically ventilated children

OBJECTIVE

To quantify the effects of neuromuscular blockade (NMB) on energy expenditure for intubated, mechanically ventilated, critically ill children.

DESIGN

A prospective, unblinded clinical study. Each subject was studied twice, before and after establishment of NMB.

SETTING

A tertiary care pediatric intensive care unit.

PATIENTS

Critically ill children undergoing mechanical ventilation and receiving ongoing sedation were eligible, if they had a cuffed endotracheal tube and were physiologically stable.

INTERVENTIONS

A total of 20 children (age, 1 to 15 yrs) were studied in an unblinded, crossover fashion. All were mechanically ventilated via a cuffed endotracheal tube, with ventilator rate and tidal volume adequate to provide complete ventilation, and F(IO2) <0.6. Absence of gas leak around the endotracheal tube was assured, and all patients were sedated using continuous infusions of midazolam and/or fentanyl; no changes in ventilator settings, nutritional input, or inotropic drug dose were permitted during the study period. Each patient underwent indirect calorimetry immediately before establishment of NMB. NMB was then induced, and indirect calorimetry was repeated. Complete blockade was verified using a peripheral nerve stimulator. In each case, the two sets of measurements were completed within a 1-hr period.

MEASUREMENTS AND MAIN RESULTS

Data analyzed included identifying and diagnostic information, oxygen consumption, and carbon dioxide production. Energy expenditure was calculated using standard formulas. Oxygen consumption and energy expenditure values obtained before and after the establishment of NMB were compared by using paired Student's t-test. NMB reduced oxygen consumption from 6.54+/-0.49 mL/kg/min to 5.90+/-0.40 ml/kg/min, and energy expenditure was reduced from 46.5+/-3.7 kcal/kg/24 hrs to 41.0+/-2.8 kcal/kg/24 hrs (p < .001 in each case). The reduction in oxygen consumption was 8.7+/-1.7%, and that in energy expenditure 10.3+/-1.8%, of pre-NMB values, respectively.

CONCLUSION

NMB significantly reduces oxygen consumption and energy expenditure in critically ill children who are sedated and mechanically ventilated; the degree of reduction is small.

Energy expenditure in acetaminophen-induced fulminant hepatic failure

OBJECTIVE

To determine energy expenditure in critically ill patients suffering from acetaminophen-induced fulminant hepatic failure and compare it with values obtained in matched, healthy control subjects and in patients studied during the anhepatic period of elective liver transplantation.

DESIGN

Prospective, controlled, observational study.

SETTING

A ten-bed intensive therapy unit and a liver transplant unit at a University teaching hospital.

PATIENTS AND SUBJECTS

Sixteen patients suffering from acetaminophen-induced fulminant hepatic failure who were sedated, paralyzed, and mechanically ventilated; 16 age-, gender-, and weight-matched, awake, healthy control subjects; and 16 patients with chronic liver disease, undergoing elective liver transplantation, who were studied during the anhepatic period of surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The mean energy expenditure was calculated in each case for a 30-min period, using indirect calorimetry. In the patients undergoing liver transplantation, measurements were performed after clamping the hepatic veins and recipient hepatectomy. Energy expenditure was markedly increased in the fulminant hepatic failure group (mean energy expenditure, 4.05 [SD 0.52] kJ x kg(-1) x hr(-1)), in comparison with healthy control subjects (mean, 3.44 [0.27] kJ x kg(-1) x hr(-1); mean difference, 18%; p < .001) and in comparison with patients during the anhepatic period of liver transplantation (mean, 3.15 [0.61] kJ x kg(-1) x hr(-1); mean difference, 29%; p < .001). These differences were even more pronounced when a correction factor for differences in core temperature was included in the calculation. Harris-Benedict predictions of energy expenditure were unreliable in the patients with acute liver failure. No correlations were found among energy expenditure and hemodynamic variables, the requirement for vasoconstrictors, or the presence of renal failure.

CONCLUSIONS

Despite the loss of functioning liver cell mass, the metabolic rate is substantially increased in patients with acetaminophen-induced fulminant hepatic failure. This finding is consistent with the marked systemic inflammatory response, which accompanies acute hepatic failure. The Harris-Benedict equation is unreliable when an estimation of energy expenditure is required in patients with this condition.

Impact of acute illness on nutritional status of infants and young children with sickle cell disease

OBJECTIVE

To evaluate changes in growth, nutritional status, body composition, and energy and nutrient intakes during illness and usual state of health in infants and young children with sickle cell disease.

DESIGN

Sixteen children, aged 0.4 to 5.6 years, with SS type sickle cell disease (SCD-SS) were assessed at the time of hospital admission for an acute illness episode and during an 18-hour overnight follow-up visit 2 to 6 weeks after the acute illness episode when in a state of usual health. Main outcome measures included growth in height and weight compared with reference standards, body composition determined by the skinfold thickness technique and total body electrical conductivity, and dietary intake determined by 24-hour recall during hospital admission and at follow-up.

RESULTS

Height, weight, and weight-for-height z scores did not differ from national reference data; triceps skinfold thickness and arm fat area z scores were less. Mean +/- standard error body fat was 15.6 +/- 2.1% at the time of hospital admission, as measured by total body electrical conductivity, and was not significantly different from the follow-up value (16.2 +/- 2.2%). Mean energy intake was 44 +/- 9% of Recommended Dietary Allowances at the time of admission and differed significantly from the follow-up value of 90 +/- 9% (P < .05).

APPLICATIONS

Infants and children with sickle cell disease appear to be at nutritional risk during an acute illness episode, as indicated by body fat measures and inadequate intakes of energy and macronutrients. Energy intake may be suboptimal for several days surrounding an admission for an acute illness in children with sickle cell disease. Physicians and other health practitioners should be alert to inadequate nutrient intakes of their patients during this time period and may consider supplemental energy to avoid a potential net negative energy balance.

Oxygen consumption in the early postinjury period: use of continuous, on-line indirect calorimetry

OBJECTIVE

To determine the patterns of oxygen consumption (Vo2) using indirect calorimetry (IC) for the first 24 hrs after serious blunt traumatic injury.

DESIGN

Prospective, observational study.

SETTING

Surgical intensive care unit of a Level 1 trauma center.

PATIENTS

Sixty-six mechanically ventilated patients with blunt traumatic injury and Injury Severity Score >15.

INTERVENTIONS

IC for 24 hrs postinjury. Patients were resuscitated to standard parameters of perfusion.

MEASUREMENTS AND MAIN RESULTS

Mean patient age was 50.1+/-18.7 yrs with a mean Injury Severity Score 30.7+/-11.3). Mean Vo2 for all patients for the 24-hr study period was 168.5+/-29.5 mL/min/m2. The level of Vo2 was not related to Injury Severity Score, the number or combination of organ systems injured, or to the use of vasoactive agents. Patients >65 yrs of age had significantly lower Vo2 (P = .0038) compared with patients < or =50 yrs. Vo2 did not change over time after resuscitation to normal parameters of perfusion. Mean Vo2 was 156.5+/-63.2 mL/min/m2 in patients who developed multiple organ dysfunction, and 172.4+/-33.3 mL/min/m2 in those who did not develop multiple organ dysfunction (p = .16).

CONCLUSIONS

Seriously injured patients are hypermetabolic in the early postinjury period. The level of Vo2 is unrelated to injury severity or number of organ systems involved. Elderly patients can be expected to have lower levels of Vo2. Vo2 does not change significantly in response to resuscitation to normal parameters of perfusion. Vo2 measured by IC did not predict the development of multiple organ dysfunction.

Energy expenditure and severity of injury and illness indices in multiple trauma patients

OBJECTIVE

To determine whether the energy expenditure of mechanically ventilated multiple trauma patients correlates with the severity of injury and illness indices before important systemic infection has complicated the clinical course, and to compare the energy expenditure with the energy expenditure expected from the Harris-Benedict equation adjusted with correction factors for trauma.

DESIGN

Prospective, clinical study.

SETTING

General intensive care unit of a university teaching hospital.

PATIENTS

Immediate multiple trauma adult patients who required mechanical ventilation.

INTERVENTIONS

Metabolic cart connected to the ventilator.

MEASUREMENTS AND MAIN RESULTS

Data on admission to the emergency department and during the first 24 hrs of intensive care unit admission were collected for computation of severity of injury and illness indices, respectively. Resting and total energy expenditures were derived at least 48 hrs after intensive care unit admission by continuous indirect calorimetry. Predicted basal energy expenditure was obtained using the Harris-Benedict equation and predicted total energy expenditure was calculated using the Harris-Benedict value adjusted with correction factors for trauma. Twenty-six multiple trauma adult patients completed the study. No statistically significant correlations were observed between both the resting energy expenditure and the total energy expenditure and the Injury Severity Score, Revised Trauma Score, Simplified Acute Physiologic Score II, Acute Physiology and Chronic Health Evaluation II score, and Glasgow Coma Scale score. A regression model of total energy expenditure was developed with the following variables: Harris-Benedict equation, heart rate, and minute ventilation (p = .01; r2 = .74). The resting energy expenditure/predicted basal energy expenditure ratio was 1.17+/-0.2 and the total energy expenditure/predicted total energy expenditure ratio was 0.76+/-0.1.

CONCLUSIONS

In mechanically ventilated multiple trauma patients the energy expenditure is not correlated to the severity of injury and illness indices but is dependent on the Harris-Benedict equation in addition to heart rate and minute ventilation. Furthermore, this patient population is characterized by a moderate state of hypermetabolism, and the Harris-Benedict prediction modified with correction factors for trauma systematically overestimates the total energy expenditure.

Effects of ventilator resetting on indirect calorimetry measurement in the critically ill surgical patient

OBJECTIVE

To evaluate the effect of acute changes in minute ventilation (VE) on oxygen consumption (VO2), carbon dioxide production (VCO2), respiratory quotient, and energy expenditure during volume-controlled mechanical ventilation in the critically ill surgical patient. The effects on some oxygen transport variables were assessed as well.

DESIGN

Prospective, randomized clinical study

SETTING

Adult surgical intensive care unit of a university teaching hospital.

PATIENTS

Twenty adult critically ill surgical patients were studied during volume-controlled mechanical ventilation.

INTERVENTIONS

After a basal period of stability (no changes over time in body temperature, energy expenditure, blood gases, acid-base status, cardiac output, and ventilatory parameters), VE was then randomly either increased or reduced (+/-35%) by a change in tidal volume (VT), while respiratory rate and inspiratory/expiratory ratio were kept constant. Settings were then maintained for 120 mins. During the study, patients were sedated and paralyzed.

MEASUREMENTS AND MAIN RESULTS

VO2, VCO2, and respiratory quotient were measured continuously by a Nellcor Puritan Bennett 7250 metabolic monitor (Nellcor Puritan Bennett, Carlsbad, CA). Hemodynamic and oxygen transport parameters were obtained every 15 mins during the study. Despite large changes in VE, VO2 and energy expenditure did not change significantly either in the increased or in the reduced VE groups. After 15 mins, VCO2 and respiratory quotient changed significantly after ventilator resetting. VCO2 increased by 10.5 +/- 1.1% (from 2.5 +/- 0.10 to 2.8 +/- 0.12 mL/min/kg, p< .01) in the increased VE group and decreased by 12.4 +/- 2.1% (from 2.7 +/- 0.17 to 2.4 +/- 0.16 mL/min/kg, p< .01) in the reduced VE group. Similarly, respiratory quotient increased by 16.2% +/- 2.2% (from 0.87 +/- 0.02 to 1.02 +/- 0.02, p< .01) and decreased by 17.2% +/- 1.8% (from 0.88 +/- 0.02 to 0.73 +/- 0.02, p< .01). VCO2 normalized in the reduced VE group, but remained higher than baseline in the increased VE group. Respiratory quotient did not normalize in both groups and remained significantly different from baseline at the end of the study. Cardiac index, oxygen delivery, and mixed venous oxygen saturation increased, while oxygen extraction index decreased significantly in the reduced VE group. Neither of the mentioned parameters changed significantly in the increased VE group.

CONCLUSIONS

We conclude that, during controlled mechanical ventilation, the time course and the magnitude of the effect on gas exchange and energy expenditure measurements caused by acute changes in VE suggest that VO2 and energy expenditure measurements can be used reliably to evaluate and quantify metabolic events and that VCO2 and respiratory quotient measurements are useless for metabolic purposes at least for 120 mins after ventilator resetting.

Evaluation of pain in the critically ill patient

This article reviews the evaluation of pain in critically ill patients of all ages. Sources of pain and its physiologic significance are discussed. Factors influencing pain, perception, and behavior are also addressed to broaden health care professionals' vision of the difficulties associated with accurate pain assessment. The evaluation process, including a discussion of several tools ranging from visual analog scales to bispectral analysis, as well as goals of therapy are discussed. Finally, a practical approach to the assessment process, which supports the need for established, regularly used evaluation and treatment protocols, is proposed.

Adverse responses to analgesia, sedation, and neuromuscular blocking agents in infants and children

Analgesics, sedation, and neuromuscular blocking agents are commonly used in treating critically ill infants and children. Although these medications are beneficial and imperative to the care of the child, their use is not risk free. Adverse responses occur in these children. With improved methods for use and monitoring, adverse responses can be minimized.

Energy expenditure in patients with multiple organ failure

We measured the level of resting energy expenditure (BEE) and its evolution in patients with multiple organ failure (MOF). We studied 30 patients requiring mechanical ventilation and sedation. REE was measured by means of a closed circuit method on days 1-5, 7, 10 and 14 after initiating the protocol. REE values between 115% and 145% of the REE calculated from the Harris-Benedict's formula were considered as moderate hypermetabolism and values above 145% as severe hypermetabolism. A predictive formula for determining caloric requirements was developed and validated in another 25 MOF patients. In the study group, 25 patients presented moderate hypermetabolism (83%) and two severe hypermetabolism(7%). Mean REE in the whole group was stable but individual patients may have had a large variability in REE. The anthropometric variables, body temperature and reason for admission predicted the REE with a coefficient of determination of 0.73, according to the model: REE= -3295 + 105.5S - 8A + 11.7 W + 7.7 H + 93.2 T + 123.1 Tr - 145.6 Su where: S = sex (male = 1, female = 0); A: age in years; W: weight in Kg; H: height in cm; T: temperature in degrees C; Tr: trauma (Tr = 1); Su: surgical (Su = 1). The reliability of the model, taken from the validation group, showed that the shrinkage was 0.8%. In conclusion, when MOF patients are sedated they present moderate hypermetabolism. Day-to-day variability of REE in the individual patients and the large variability in estimating REE with our formula preclude its clinical utility and we recommend to measure REE in MOF patients.

Spontaneous haemothorax: an unusual presentation of primary lung cancer

An unusual case of spontaneous haemothorax caused by a subpleural primary lung cancer is reported. Tumour invasion of the pulmonary vessels and visceral pleura was the possible cause.

Thermogenic response to total parenteral nutrition in depleted patients with multiple organ failure

Nutrient-induced thermogenesis was studied in eight patients with severe nutritional depletion and multiple organ failure after abdominal surgery. Energy expenditure (EE) and RQ were recorded continuously over a period of 4 days. On each study day balanced total parenteral nutrition was administered during a period of approximately 16 h, followed by a period of low-energy glucose infusion. The total energy supply was in the order of 110% of the measured EE and the supply of glucose, fat and amino-acids was 2.6 +/- 0.4, 2.6 +/- 0.2 and 0.84 +/- 0.2 kJ x kg BW(-1) x h(-1) (mean +/- SD), respectively. The nutrient-induced thermogenesis, expressed as the rise in EE in percent of the energy content of the administered nutrients, was approximately 5%, which appears to be lower than previously observed in healthy individuals. A plateau in energy expenditure was reached after 6-8 h in response to parenteral nutrition. It is hypothesized that this plateau reflects the oxidative capacity and thus may be used as a guideline for nutritional therapy.

Total parenteral nutrition in patients with intra-aortic balloon counterpulsation

The effects of total parenteral nutrition (TPN) were studied in nine of 19 patients with intra-aortic balloon pumping TPN (c. 27 kcal/kg/day) was begun 3 hours after the start of pumping. The non-protein caloric source was composed of hypertonic dextrose and fat emulsion (60% and 40%). The nitrogen intake was 1 g/150-200 kcal/day. The ten control patients received 5% dextrose in corresponding volume/hour. Hemodynamic studies were performed before and 24, 48 and 72 hours after the start of counterpulsation. The predicted and the observed resting energy expenditure were recorded in both patient groups during counter-pulsation. Systemic and pulmonary vascular resistance differed significantly between the groups. Cardiac function improved in both groups. In the TPN group the measured resting energy expenditure increased by 33% more than predicted on day 2 and by 56% on day 3 and in the controls the figures were 31% and 40%--all rises significant. Total parenteral nutrition with low fat content thus alters the hemodynamic equilibrium without clinically significant effects in patients undergoing intra-aortic balloon pumping. These patients are hypermetabolic and should receive artificial nutrition as soon as possible.

Energy expenditure and outcome in patients with multiple organ failure following abdominal surgery

A possible relationship between hypermetabolism (energy expenditure expressed as percentage above the estimated basal metabolic rate) and clinical outcome was investigated in 29 artificially ventilated patients with infection and multiple organ failure following abdominal surgery. The average energy expenditure and hypermetabolism were 126 +/- 19 kJ (30 +/- 5 kcal)/kg/24 h and 36 +/- 12%, respectively. Survivors of the intensive care period (n = 20) had a 15% higher hypermetabolism (41 +/- 11 vs 26 +/- 8%, p less than 0.01) than patients who died in the intensive care unit (n = 9). Six of the patients died after intensive care. On comparing hypermetabolism in survivors (n = 14) and non-survivors (n = 15) of the period of hospitalization, no significant difference was discernible. The results demonstrate that patients with multiple organ failure have a moderate hypermetabolism and suggest that the hypermetabolism is comparatively reduced in patients with a fatal outcome during intensive care.

Oxygen homeostasis: theory, measurement, and therapeutic implications

The ultimate goal of therapeutic intervention in a critically ill patient is to maintain oxygen homeostasis where delivery of oxygen to the cells is greater than, or at least equal to, the oxygen demand of the cells. Oxygen demand varies from organ to organ. Total body oxygen demand is the sum of all oxygen required by all tissues and organs for aerobic cellular function. Oxygen consumption (VO2) is the quantity of oxygen actually used by the cells. VO2 may be calculated if the values of cardiac output (CO), hemoglobin concentration, and arterial and venous oxygen saturations (SaO2 and SvO2, respectively) are known. Under normal circumstances, the quantities of oxygen demanded and oxygen consumed are equal, but in situations of inadequate oxygen delivery, oxygen demand may not be satisfied and the quantity of oxygen actually consumed will be governed by the quantity delivered. This then may result in an oxygen deficit and, ultimately, cellular death. This article discusses the principles of oxygen homeostasis, techniques for measuring VO2, CO, and SvO2, and the relevance of these principles and techniques to clinical practice.

Nutritional support in the critical care setting (Part 1)

Over the past two decades nutritional support has rapidly become an integral part of the medical care of critically ill patients. As scientific evidence accumulates supporting the important role of underlying nutritional status in determining the eventual outcome of many illnesses, aggressive nutritional intervention has become commonplace in our medical and surgical ICUs. However, nutritional support, particularly parenteral alimentation, is expensive and associated with important morbidity and even mortality. Furthermore, definite evidence of its clinical efficacy under certain specific conditions is often lacking and in need of properly done prospective studies. This review summarizes the basic principles of nutrition as applied to the critically ill patient in the clinical setting. Special emphasis is on practical considerations regarding cost, efficacy (or lack thereof), and potential advantages, disadvantages, and risk of complications of each proposed approach.