Diagnostic Techniques

Tuesday, October 29 5:00-7:30

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Critical Care: ICU Monitoring/Diagnostic Techniques A NEW VOLUME ACCUMULATING EXPIRATORY GAS ANALYSIS SYSTEM S Miodownik, MEE, J Melendez, MD Memorial Sloan Kettering Cancer Center Cornell University Medical College New York, NY

FEEDING TOLERANCE IS ENHANCED BY NASOJEJUNAL PLACEMENT OF FEEDS IN CRITICALLY ILL PATIENTS William Cook MD, A Chendrasekhar MD, GA Timberlake MD--West Virginia University, Morgantown, WV, USA

PURPOSE: The measurement of 02 consumption, C02 production and other metabolic parameters can be useful in managing mechanically ventilated patients in the intensive care setting. A large number of constraints in this environment render conventional devices for this purpose ineffective and inaccurate. \Ve have developed a novel technique for the continuous measurement of gas exchange that requires no flow measuring device and can maintain an acceptable degree of accuracy over a wide range of FI02 . METHODS: Two 60 liter Douglas gas collection bags are alternately connected to the subject" s exhaled gases via an automated valve manifold system controlled by a laptop computer. As one bag is being analyzed, the other collects. Volume is determined by indicator dilution technique and is totally independent of the flow pattern of the expired ga•. Gas concentrations are automatically measured by a Marquette Electronics RAMS quadrupole Mass Spectrometer. At the completion of analysis, the collected bag is evacuated and made ready for the next collection. Each collection interval is 120 sec. long and results are displayed in comparable intervals. All results are expressed in meann ::!: S.D. RESULTS: The system and software were easy to use and, once initialized, measurements proceeded continuously and automatically. In simulations, we have successfully measured volumes over the range of 5 to 50 liters with aS .D. of l-3%. These volumes were collected at FI02 of 0.21, 0.4, 0.5, and 0.8. Additional tests with a methanol burning lung model yielded repeatable RQ values of0.67::!:0.0l. CONCLUSIONS: We have developed a novel and accurate system for collecting and measuring respired gases that has the potential to operate and provide accurate results in the demanding critical care environment of high Fi02. Unlike other systems, this method has the flexibility of studying other expiratory gases. CLINICAL IMPLICATIONS: The inaccuracy of gas exchange measurements in a high Fi0 2 setting has precluded the wide spread use of the metabolic monitoring of the critically ill patient. Our technique may provide the opportunity to study metabolics at high Fi02 . The integrated expired sample available via our technique may provide a window into many aspects of metabolic activity beyond vco2 and vo2.

Purpose: Aspiration with regard to location of feeds is often discussed. Tolerance to feeds by location within the gastrointestinal tract has not been completely evaluated. We hypothesized that feeding tube location effects feeding tolerance. Methods: A prospective cohort analysis of 61 surgical intensive care unit patients that were attempted to be fed enterally. Abdominal radiographs were reviewed to localize the feeding tube either into the stomach/proximal duodenum or distal duodenum/jejunum. The vertebral column was used to distinguish the proximal from distal duodenum. Tolerance was defined as being able to reach nutritionally targeted levels of enteral feeds within 48 hours of tube placement. Results: Twenty two patients had feeding tubes placed in the distal duodenum/jejunum. Thirty nine patients had their feeding tube placed in the stomach/proximal duodenum. The percentage of patients tolerating feeds in each group is listed below: Stomach/proximal duodenum = 16/39 (41.03%) Distal duodenum/jejunum= 19/22 (86.36%)* (p=0.0004). Conclusions: Critically ill surgical patients are significantly more tolerant of distal duodenal!jejunal placement of feedings than proximally placed feedings. Clinical Implications: Nasojejunal tube placement may avoid feeding intolerance and delays in attaining adequate enteral nutrition.

COMPARISON OF pHi AND MUCOSAL-ARTERIAL C02 GAP AS PREDICTORS OF OUTCOME IN TRAUMA PATIENTS Preston R Miller MD, MC Chang MD, JW Meredith MD Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, NC.

DOPPLER DERIVED DATA IN DETECTION OF COMPARTMENT SYNDROME Akella Chendrasekhar, MD; E Czinege, MD; GA Timberlake, MD West Virginia University, Morgantown, WV, USA

Purpose: Gastric intramucosal pH (pHi) has been used as an organ specific monitor and predictor of outcome during resuscitation. However, pHi has both systemic (arterial HC03) and organ-specific (intrarnucosal C02) determinants. Critics state tllis impairs the usefulness of pHi as a regional monitor, and an alternative value, the mucosal-arterial C02 gap (GAP) may be better. GAP widens with decreased gastric perfusion. Our purpose was to evaluate pHi and its components (HC03 and C02 expressed as GAP) as predictors of mortality and multiple organ failure (MOF) in trauma patients. Methods: Design: Cohort study of 79 trauma patients. Seymg: university level I trauma center. ~alysis: receiver operating characteristic curves or mortality and MOF were constructe using values at 24 hours of pHi, GAP (torr), and HC03 (mEq!L). Values maximizing specificity and sensitivity were determined from these curves. The ability of each variable to predict mortality and MOF was evaluated using odds ratios (OR) and chi-square. Significance is defined as p<0.05. Results: pHi< 7.25 predicted both death (n=l7) and MOF (n=l2). Low HC03 predicted death, but not MOF. Increased GAP alone predicted neither death nor MOF.

Purpose: Compartment syndrome is a condition that develops when elevated pressures within a limited space compromise the circulation and the function of the tissues within that space. The diagnosis of compartment syndrome is currently performed by an unreliable clinical exam or by invasive methods. We tested the utility of a doppler device in detecting compartment syndrome in a simulated model. Methods: We simulated compartment syndrome by placing a blood pressure cuff on the fore-arm of 15 volunteers and increased the cuff pressure up to the diastolic blood pressure of that person. Compartment pressure is within 30 mm Hg of the patient's diastolic pressure is traditionally diagnosed as compartment syndrome. Doppler measurement was taken at the wrist at each cuff pressure level. The doppler de~ved velocity tracing was analyzed for peak velocity (em/sec) and acceleration (em/sec ). Arterial saturation by pulse oximetry was also obtained distal to the pressure cuff. Statistical analysis of the data were performed by using one way analysis of variance with repeated measures comparing simulated compartment syndrome with baseline values (deflated

Table l. pHi vs. death pHi vs. MOF HC03 vs. death HC03vs. MOF GAP vs. death GAP vs. MOF

Cutoff <7.25 <7.25 <17.2 <17.2 <17.6 <12.1

OR 5.38 4.46 7.28 3.37 2.92 2.10

p <0.01 <0.05 <0.01

NS

NS NS

Conclusions: pHi is a better predictor of death and MOF than its constituents. A cutoff of 7.25 maximizes the positive and negative predictive value of pHi vs. outcome. Clinical Implications: Gastric tonometry is a useful predictor of outcome in trauma patients. pHi, not C02 gap, should be used because both the systemic and organ specific components of pHi are necessary for its use as a predictive tool. In addition, a cutoff of pHi<7.25 is better than previously proposed values (7.32 or 7.3) in predicting outcome. Further research should be directed towards defining the role of tonometry in guiding resuscitation.

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cuff).

Results: Doppler and pulse oximetry derived data are listed below:

Peak Velocity Acceleration Arterial Saturation *p < 0.0001, mean values ::':: SEM

Baseline 13.9::'::0.9 191.7::'::6.9 98.1::'::0.2

Compartment syndrome 4.9::'::0.9* 190.0::'::6.9 98.5::'::0.2

Conclusions: Doppler derived peak velocity is a noninvasive technique that tracks tllis simulated compartment syndrome model with tremendous accuracy. The lack of change in acceleration may provide a new approach to differentiate compartment syndrome from arterial occlusion as arterial occlusion has been shown to reduce acceleration.

Clinical Implications: Bedside doppler is a noninvasive technique for monitoring patients at risk for compartment syndrome.

Abstracts of Original Investigations, CHEST 1996

Tuesday, October 29 5:00-7:30

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Critical Care: /CU Monitoring/Diagnostic Techniques, continued ADVERSE EFFECTS OF SUDDEN DISCONTINUATION OF INHALED NITRIC OXIDE An nick Lavoie, S. Bhorade, M . O 'Connor, A. Pohlman, J. Hall-University of Chicago, Chicago, IL. USA.

NUTRITIONAL PARAMETERS AS PREDICTORS OF VENTILATOR DEPENDENCE Akella Chendrasekhar MD, GA Timberlake MD West Virginia University, Morgantown, WV, USA

Purpose: Inhaled nitric oxide (NO), a selective pulmonatyvasodilator, has been r eported to have beneficial effects in patients with adult respiratory distress syndrome and acute right heart syndrome. However, sudden discontinuation could cause acute pulmonary hype rtension leading to he modynamic instability and arterial oxygen desaturation. The consequences of acute withdrawal of inhaled NO in patients has not been well studied. Methods: Thirty four patients requi1ing mechanical ventilation for either acute hypoxic respiratory failure or acute right heart failure were treated with inhaled NO. Patients that initially benefited from inhaled NO were maintained on NO and had daily discontinuation of therapy to confirm ongoing benefit. Can:hovascular and gas exchange parameters were monitored before and after NO withdrawal. Results: 56% (19/34) patients initially showed an improve ment with inhaled NO and subsequently underwent daily trials of NO withdrawal. 63% (12119) patients manifested evidence of decompensation 'vithin minutes of NO withdrawal. Four patients developed h emodynamic instability as documented by SBP<90. Eight patients desaturated to 85% or below. Seven patie nts who initially decompensated after withdrawal of inhaled NO had their dose of NO gradually reduced and subsequent measure ments made. Of these patients, four were able to be weaned from the NO. Conclusions: We conclude that 1) decompensation after withdrawal of inhaled NO occurs in a significant proportion of patients who initially sustained a benefit from this therapy, 2) the degree of the decompensation is variable, causing desaturation in some patients , but leading to he modynamic compromise and cardiovascular collapse in extreme cases; 3) decompensation can be seen as early as three hours after initiating NO; 4) some patients with this decompensation may benefit from weaning inhaled NO therapy. Clinical Implication: Patients receiving inhaled NO may decompensate during withdrawal of the rapy and must be carefully monitored to avoid this problem.

Introduction: Ventilator dependence is commonly seen in malnourished critically ill surgical patients. We hypothesized that there is a relationship between initial nutritional parameters and duration of mechanical ventilation (MV) in a surgical intensive care unit population. Methods: A prospective cohort analysis on 49 consecutive critically ill trauma patients (ISS > 20) was pe1formed. Nutritional parameters (serum albumin and serum pre-albumin) obtained within 48 hours of initiation of mechanical ventilation. Total duration of mechanical ventilation and routine parameters such as age and sex were also obtained on all patients. A bivariate analysis with a 95% confidence el vel was pe1formed to assess correlation between data, one way analysis of variance (ANOVA) was used to mmpare data between elderly (age> 65) and young (age <65) patients Results: The age of the population evaluated ranged from 18 to 85. Duration of MV inversely correlated with pre-albumin (p=0.018). Albumin level failed to correlate with duration of MV. There was no difference related to the sex of the patients. A comparison of data from elderly and young patients is listed below:

RECTAL MUCOSAL SURFACE PH CORRELATES WITH GASTRIC INTRAMUCOSAL PH IN SEVERELY TRAUMATIZED PATIENTS Akella Chendrasekhar MD, G Prabhakar MD , JC Fage rli MD, GA Timberlake MD \'Vest Virginia University, Iowa Methodist Me dical Center, DesMoines, IA, USA Introduction: Gastric intramucosal pH as de rived by tonometry is currently an accepted modality for tracking gastrointestinal perfusion. Rectal mucosal surface pH has been shown to correlate with tonometrically derived values in both endotoxic and he morrhagic shock states. We hypothesized that rectal mucosal surface pH correlates with tonometrically de rived intramucosal pH in both shock and resuscitated states in trauma patie nts. Methods: We performed a prospective evaluation of 12 severely traumatized patients (ISS>20). After informed consent was obtained, a gastric tonometer and rectal pH probe were placed in all patients. Rectal mucosal pH measure ments we re take n within 5 minutes of tonometric measurements. Bivariate analysis was performed to assess the degree of correlation between tonom etric data and rectal mucosal surface pH. Results: Six men and six women were enrolled in the study. Ages range d between 18 to 64 with a mean age of 42.3 years. A total of 280 sets of data points were obtained. Rectal mucosal surface pH showed a high degree of correlation with tonometrically derived gastric intramucosal pH (R 2 =0.8l, p < 0.0001). Conclusions: Rectal mucosal surface pH correlates with tonometrically derived gastric intramucosal pH. Clinical Implications: Rectal mucosal surface pH is a simple method to obtain data regarding gastrointestinal pe rfusion.

Vent days Pre-albumin Albumin *p=0.012, **p=0.0019, •p=n.s.

Elderly patients (n=l9) 18.7::'::2.1 * 11.6::'::1.2** 2.3::'::0.1 +

Young patients (n=30) 11.5::'::1.7 16.5::'::0.9 2.7::'::0.1

Conclusions: Elderly patients had initial prealbumin levels lower than younger patients consistent with poorer nutritional status. Elderly patients also had longer duration of MV as compared to younger patients. Albumin level failed to correlate with duration of MV. Serum pre-albumin level accurately predicts need for prolonged mechanical ventilation. Clinical Implications: Early nutritional evaluation may be critically important in the elderly patient.

PERIOPERATIVE MYOCARDIAL INFARCTION MORTALITY IS SIMILAR TO MORTALITY FROM ACUTE MYOCARDIAL INFARCTION Samuel K Appavu, MD, FCCP; T R Haley, MD and S R Patel, MD-Division of Surgical Critical Care, Cook County Hospital and the University of Illinois College of Medicine, Chicago, Illinois, USA Purpose: Perioperative myocardial infarction (PMI ) has been shown to cause a very high mortality rate ranging from 92% (Vormittag, 1965-1972) to 23% (Rao, 1987-1989). We perfonned this prospective study to determine whether or not this high rate of PMI mortality continues to prevail. We hypothesized that PMI mortality has remained unchanged since the last decade. Methods: Non-cardiac surgical patients entering the Surgical Intensive Care Unit postoperatively, with age>40 years, pre-existing cardiadvascular disease, prolonged operations, major blood loss or suspicion of PMI were studied. PMI workup included 3sets of electrocardiograms (ECG) and 3 sets of creatine kinase MB fraction (CK-MB) determinations performed at 8 hour intervals. Data collection included age, diagnoses, preoperative ECG, durations of anesthesia and surgery, operative blood loss, intraoperative electrocardiographic and hemodynamic events, results of PMI workup and patient outcome. Statistical analysis consisted of calculation of descriptive statistics and comparison of patients without and with PMI by Student t test. A P value of <0.05 was considered to be significant. Results: One hundred fifteen patients, 51 males and 64 females with the mean age of 63.6::'::10.6 (SO) years entered the study. There were 55 vascular, 35 abdominal and 25 other operative procedures. There were 65 prolonged intraoperative hypotensive episodes and 57 incidences of hemorrhage (>500 ml). Intraoperative ECG changes occurred in 2 patients only. PMI occurred in 7 patients. A statistical comparison of patients without and with PMI with respect to age, durations of anesthesia and surgery, intraoperative vital signs and blood loss demonstrated no significant difference except for mean operative blood loss (1032-9 ml for non PMI patients vs 3333-3 ml for PMI patients, P<-001 ). One of 7 (14.3%) PMI patients and 6 of 108 (5.5%) non PMI patients died. Conclusions: The mortality rate of PMI (14%) is similar to the mortality rate for patients with acute myocardial infarction who reach the hospital alive (15%). Clinical Implications: Aggressive monitoring and management of PMI can greatly reduce its mortality rate.

CHEST I 110 I 4 I OCTOBER, 1996 SUPPLEMENT

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Tuesday, October 29 5:00-7:30

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Critical Care: ICU Monitoring/Diagnostic Techniques, continued A PILOT STUDY OF INTENSIVE CARE UNIT ARCHITECTURAL DESIGN ON PATIENT MORTALITY AND LENGTH OF STAY Michelle C Tenhengel, RN, BSN; MS Forshag, MD; MJ Boyle, MS- Carolinas Medical Center, Charlotte, North Carolina, USA

ARE POST-INTUBATION CHEST X-RAYS NECESSARY? David R Gerber, DO, FCCP CR Aseron, MD, R Ranasinghe, Mii MR Pratter, MD, FCCP Division of Pulmonary and Critical Care Medicine Cooper Hospital!UMC UMDNJIRWJMS, Camden, NJ USA

Purpose: Design guidelines for intensive care units stress a direct lineof-sight (DLOS) from the nursing station into each room. The premise is that this will enhance patient outcomes through a higher level of visual monitoring of the patient and the in-room monitors. However, there is no study documenting such a benefit. Older hospitals often were designed with long, narrow wards. Retrofitting such a hospital with a DLOS ICU may be difficult and expensive. This study was designed to compare the effect of a DLOS on patient mortality and length of stay in the ICU. Methods: One ICU of Carolinas Medical Center has its rooms arrayed linearly on both sides of a long hallway. Patients in four rooms with DLOS were compared with those in four rooms out of direct sight from the nursing station. This was done by a retrospective review of all admissions lasting greater than 24 hours to these rooms between September 1, 1995 and November 26, 1995. Data collected included room assignment, basic demographics, primary admission diagnosis, APACHE II score, length of stay, and mortality. Results: Thirty-nine patients were collected from DLOS rooms and 55 from out-of-sight (OOS) rooms. These groups were comparable for age, gender, race, primary admission diagnosis, and APACHE II score. The P value from the \il/ilcoxon rank sum test for comparing smvival of patients by APACHE II score was .0017. Mortality in the DLOS group was 5.1 %; in the OOS group it was 10.9% (P value=.46). Also, room location did not have effect on length of stay (P value = .73). Conclusions: The effect of DLOS or OOS room location appears to have small or no effect on mortality and length of stay, relative to degree of illness as measured by APACHE II score. Clinical Implications: Extensive and costly renovations of existing structures may not be merited. Further study, including remote monitoring options, should be considered.

Purpose: To evaluate the ability of critical care (CC M) physicians to predict post-intubation chest x-ray results, to help determine whether such x-rays are routinely required in the ICU. Methods: Prospective observational study of all patients intubated by CCM staff and fellows, in a 10 bed medical/surgical ICU and 9 b ed intermediate ICU. Following intubation a data form was filled out with patient, operator, and procedural data and predicted x-ray findings (endotracheal [ET] tube position, pulmonary complications of intubation). All patients then had stat post -procedural films performed as per our unit protocol. Films were reviewed by the CCM team, and the results were then recorded. Results: 34 cases have been recorded thus far. ET placement of the tube was confirmed by end-tidal C02 and physical findings (bilateral breath sounds, condensation, etc.) in all. None had obvious complications atthe time of intubation. All x-rays were predicted to demonstrate correct ET tube position. 27/34 x-rays demonstrated correct tube placement, 6/34 showed high tube placement, and in 1/34 the tube was low, but above the carina. Although new pathology such as infiltrates and pulmonary edema was detected on some fllms, no abnormalities attributable to the intubation have been identified. Conclusions: Thus far, clinically uncomplicated intubations have not been associated with pulmonary complications on chest x-ray. Although minor tube malpositions have been identified (7/34), none was clinically significant or would have acutely impacted patient well being or care. There appears to be ahigh degree of confidence on the part of the operators in the correct performance of ET intubation when the procedure is clinically uncomplicated. Clinical Implications: These preliminary results suggest that apparently uncomplicated intubations, performed by experienced operators, may not require stat x-rays solely to confirm placement and evaluate for otherwise undetected complications. Minimizing the number of such x-rays performed could result in significant cost savings.

CARDIOVASCULAR EFFECTS OF NON-INVASIVE MECHANICAL VENTILATION Akella Chendrasekhar MD, A Toughanipour MD, GA Timberlake MD, 'Nest Virginia University, Iowa Methodist Medical Center, DesMoines, lA, USA

KETOROLAC: PHARMACOKINETlCS AND EFFICACY IN THE TREATMENT OF PAIN IN CRITICALLY-ILL CHILDREN Mary Lieh-Lai, MD: R. Kauffman, MD: H. Uy, MD; P. Simpson, PhD; M. Danjin, RN-ChUdren's HospofMI!Wayne State Univ, Det., MI, USA; Children's Mercy Hosp!UnivofMissouri, K. C., MO, USA

Introduction: Invasive (endotracheal) Positive pressure ventilation has been shown to depress cardiovascular function. We hypothesized that noninvasive mechanical ventilation has no adverse hemodynamic consequences in critically ill surgical patients. Methods: We performed a prospective cohort analysis of lO critically ill patients that had a pulmonary artery catheter in place and were ventilated with non-invasive mechanical ventilation (Bipap). Bipap was initiated in all patients with 15/5 mmHg pressure support. Cardiopulmonary profiles were performed 15 minutes before initiating bipap and were repeated once the patient was on bipap for 15-20 minutes. No additional fluid boluses or inotrope changes were made during the study. Statistical analysis was performed using ANOVA. Results: The mean data for cardiac index (CI) and pulmonary capillary wedge pressure (PCWP) are listed below: CI (l!min) PCWP (mmHg) 10.3::'::1.3 3.31::'::0.18 Baseline 11.0::'::1.3* 3.25::'::0.18* Bipap *p=n.s. Conclusions: Cardiac index and PCWP during non-invasive ventilation were unchanged from baseline values. Clinical Implications: Non-invasive mechanical ventilation does not have the negative hemodynamic consequences demonstrated by endotracheal ventilation.

1405

Purpose: Ketorolac (KT) is a parenteral anti-inflammatory analgesic used for the treatment of severe pain. We studied the efficacy, safety, pharmacokinetics (PK) and metabolism of intravenous (IV) KT compared to IV morphine (MS) in children. Methods: 101 children, 3-18 yr. who were admitted to the ICU were randomized to receive a single TV dose of KT or MS. Pain was measured using the Oucher and Children's Hospital of Eastern Ontario Pain Scales (CHEOPS). Pain scores and need for remedication were compared hetween the h~o grps. Bleeding time (BT ), SGOT, BUN, creatinine, urine output and <.:om plaints of nau sea & vomiting were recorded. PK was studied in 50 children following a single IV 0.6 mglkg infusion of KT. Serial plasma samples and urine were collected following KT infusion. Racemic KT was measured in plasma; KT, KT-OH and KT-glucuronide were measured in urine.

Results: Median age was 10.8 (3-18) yr. Differen~-es behveen KT and MS in time to pain relief, and need for remedication were not significant (table 1). There we re no differences in BT, BUN, creatinine, urine output, or the incidence of nausea & vomiting between grps.

Table 1 MS (N=48) KT (N=53) P Time to pain relief 20.35±1.75 21.25±2.1 0.7 (min) Time to remed (hr) 3.1±3.0 3.5±3.0 0.34 Plasma kinetics of KT were best described by a model incorporating zero order infusion and biexponential decay. There was no correlation betvveen age and volume of distribution (Vd ), elim T\2, or clearance (CI ). A comparison of our data with KT kinetics reported in adults -is sho\-vn in table 2. Table 2 C hildren Adults 1.1±0.07 0.55 C I (mVmin!kg) Vd (llkg) 0.35 ±0.03 0.11 4.0±0.3 5.2 Elim T\2 (hr) A median of 40.6% (14.5-92.8%) of the dose was recovered in the urine: 22.8% (7.3-44%) parent drug; 9.3% (0.8-54.6%) KT-OH; and 8.7% (1.8-33.2%) as KT-gluc. Conclusions: KT is as efficacious as MS in relieving severe pain. A single dose of KT does not prolong BT, or alter renal function. Elim T\2 is shorte r, Vd larger, and C I greater in children compared to adults. Clinical Implications: KT is effective for short tenn relief of severe pain. Because of a shorter elim T \2 and larger Vd and CI, large r mglkg doses may be required in children to achieve comparable plasma cone over time. Supported in part by NICHD grant #HD31313.

Abstracts of Original Investigations, CHEST 1996

Tuesday, October 29 5:00-7:30

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Critical Care: ICU Monitoring/Diagnostic Techniques, continued DIGITAL COMPARED TO GRAPHICAL PULMONARY WEDGE PRESSURE MEASUREMENTS IN DIFFERENT VENTILATORY MODES Anthony C Campagna, MD; WA jensen, MD; RC Silveslli , MD; MB Bader, MD; C O 'Donnell, SeD- Division of Pulmonary and Critical Care Medicine, Deaconess Hospital, Harvard Medical School, Boston, Massachusetts, USA

ESTIMATION OF ARTERIAL PH FROM END-EXHALED PC02 AND TOTAL C02 CONTENTTeny Fagan, MD; Deepak P atel, MD; Ramesh Shah, MD FCCP- VA Me dical Ce nte r, Wilkes-Barre, Pennsylvania, USA

Purpose: In many hospitals, pulmonary capillary wedge pressure (PCWP) is assessed with the aid of digi tal monitors instead of graphical paper tracings. Can PCWP be estimated with acceptable accuracy fro m bedside digital monitors? Methods: For 60 critically ill patie nts, we compared PCWP measureme nts dete rmined from a Hewlett-Packard bedside digital monitor [Model 78205 A, B,CorD (n=53) or Model 78354 A (n= 7)] \vi th those dete nn ined from a desl-1op graphical strip nx:o rder. Among diffe rent patients, these measureme nt techniques w e re compared d uring spontaneous v entilation (SV, n=20), intermittent mandatory ventilation (IMV, n=17), assist/control ventilation (AC, n=13) and controlled mechanical ventilation (CV, n=IO). Assuming graphically determined measures (GW) to be the most valid estimate of PCWP , we compared those values to digital dete rminations of either systolic (SW), diastolic (OW), and mean wedge (MW) pressure fro m the bedside monitor. We oompared group mean values as we ll as cli nically s ignificant differences (CSD ) which we re defined as a graphical to digital diffe rence of "=4 mmHg. Results: Values are mean :<:: SD (rnmH g)

Purpose: This study was done to investigate whethe r arte rial pH could be estimated with reliability in a no n-invasive manner, in patie nts w ho already had a measure ment of serum total C02 content. a rial blood gases and total C0 2 Methods: Thirty patie nts w ho had rte content measured (SMA7), had in addition a mea sure me nt of end-exhaled PC0 2 using a continuously sampling infra-red capnometer. The pC0 2 measurement required a forced exhalation to full end-expiration. Using the Henderson-H asselbach equation as a model, multiple linear regression was done with the arte rial pH as the depende nt variable, and the lo garithm of the total C02 and logarithm of the end-exhaled pC02 as independent variables. Results: The patient pH values ranged from 7.29 to 7.51 and pC02 values ranged from 26 to 62. The multiple regression coeffici ent was 0.83 (R squared= 0.68). The s tandard error of the pH estimate was 0.027. All thirty patients had an estimated pH from the regression equation that was within 0.05 of their measured pH . Conclusion: In this small sample of patie nts multiple regression allowed a reasonably accurate estimation of arterial pH from total C0 2 conte nt and ger group of e nd-exhaled p C02. This te chnique will be exte nded t o a lar patie nts. Clinical Implications: A reasonably reliable estimate ofarte rial pH was seem to be possible using end-exhaled p C02, in instances where a near simultaneous total C02 content has been m easured. When pulse oximetry is also done, an estimate o f p02, pC02, and pH are thus possible.

Group

SV 20

IMV 17

AC 13

cv

SW OW MW GW Total# CSD

19.2:<:: 11.0* 10.5:<::6.5* 14.7:<::8.4* 16.8 :<:: 10.0

19.4 :<::4.1* 13.0 :<::4.4* 16.8 :<::3.3 16.4 :<::3.6

22.7 :<:: 7.6* 15.7:<::6.0 18.8:<::6. 1* 16.6:<::5.3

18.8:<::4.3 14.9:<:: 3. 7 17.7:<::3.3 15.9:<::2.9

N

4

0

10

0

*p <0.003 Conclusions: Although several graphical versus digital PCWP meas urements w ere significantly di ffere nt on statistical comparison, the rates o f lci nically significant differences were acceptably ol w among all but the spontaneously breathing patie nts. Clinical Implications: Routine use of appropriate digital wedge pressure measure ments de rived from these bedside monitors may safely be used to estimate PCVIIP in mechanically ventUated but not spontaneously breathing patients.

BEDSIDE SONOGRAPHIC GUIDED VS BLIND POSTPYLORIC FEEDING TUBE PLACEMENT IN CRITICALLY ILL PATIENTS Sergio Ruiz-Santana, MD, FCCP; CR H ernandez Socorro, MD; J Marin MD; JL Santana, MD; 0 Suarez, MD; VJ Pena, MD - Hospital del Pino, Las Palmas de G .C., SPAIN Purpose: To compare a blind manual bedside method for placing fe eding tubes into the small bowel to a sonographic be dside technique . Methods: 47 patients, hemodynamically s table, mechanically ventilated and which required anasoenteric tube placement for enteral feeding. A blind bedside method for postpyloric placement was always atte mpted first and the technique was conside red successful when a postpyloric location of the tip of the tube was achieved as shown by an abdominal roentgenogram . Howto enter the small bowel we atte mpted a f ever, if after 30 minutes w e ailed sonographic bedside technique. Finally, a nasogastric tube was inserted into the stomach . Results: The blind method was successful in 13 (27.6%) of the 47 patients and the final location of these tubes was the proximal jejunum. The a ve rage time for placement was 11.1:±::7.4 min (range 5 to 30). The sonographic technique was successful in 28 (82.3%) of the remaining patients and the final in the ( location was 7 (20%) in the second portion ofthe duodenum, 9 26%) third, and 12 (35%) in the proximal jejunum. The average time forplaceme nt was 17.9 ± 7.4 min (range 5 t o 3 5).The pyloric outlet w as os nographically severely hypokinetic in 17 patients and in 6 o f them we were unable to achieve r,ostpyloric tube placement. Cone usions: The sonographic bedside te chnique has a s uccess rate o f 82.36% (confidence interval; 65% - 93% ) after the failure o f the blind method , proving that the forme r is sig nificantly more s uc cessful. Clinical Implications: This sonographic te chnique facilitates the bedside insertion of feeding tubes in patients who cannot b e moved and in those with severe impairment of the peristaltic activity of the stomach .

POOR CORRELATION BETWEEN ARTERIAL OXYGENATION AND ABNORMALITIES ON THE CHEST RADIOGRAPH IN CRITICALLY ILL PATIENTS Scott Flanders, MD; M.Smith, MD; G. Gamsu,MD; S. Kee, MD; M.A. Matthay, MD; Cardiovascular Research Institute, Depts. of Medicine & Anesthesiology, University of California, San Francisco, CA.

Purpose: The primary objective of this study was to evaluate the relationship between abnormalities on the c hest r adiograph and deficits in arterial oxygenation in critically ill patients. Methods: 90 patients were randomly identified prospectively. All patients were intubated and had an arterial blood gas drawn within 2h of their routine morning anterior-posterior portable c hest r adiograph. The c hest radiograph was scored b y 3 independent reviewers w howere blinded to the clinical data. The radiographs were scored quantitatively for the extent and severity of edema, consolidation, atelectasis, and pleural effusions. I nte robserver variability was assessed with a Kappa statistic. The correlation between the c hest radiographic score and the alveolar-arterial oxygen gradient was determined for all patients. Regression analysis was used to test the relationship in specific subgroups such as sepsis, COPD, post-cardiac surgery, and heart failure. Results: The quantitative assessment of chest radiographic abnormalities among the 3 r veiewers was similar (mean scores of 5.9::'::4.2, 7.7::'::5.4, 7.4::':: 4.4; overall mean 7.0 ::':: 4.3.) The interobserver agreement for specific c hest r adiographic diagnostic categories (predominant edema, consolidation, a telectasis, or effusion) was faire (Kappa=.3), but improved significantly when only the more abnormal chest r adiographs (scores> 6) were inCluded (Kappa= .6). The correlation between the mean chest r adiographic score and the alveolar-arterial m.ygen gradient was poor (R= .l 7), and was not significantly improved in subgroups analyzed according to age, diagnosis, the use of vasodilators, or ventilatory parameters. Conclusions: While c hest r adiographs are an important method f or f ollowing the development and progression of acute lung disease in critically ill patients, they are a n unreliable method for estimating the severity of oxygenation d efect. Clinical Implications: The most likely explanation for this poor correlation is that distribution of pulmonary blood flow in critically ill patients with acute lung disease is not uniform , thus resulting in widely different oxygenation d efects. The chest radiograph should not b e used as a surrogate marker f orarterial oxygenation. Supported in part by NIH HL 51856. CHEST I 110 I 4 I OCTOBER, 1996 SUPPLEMENT

1415

Tuesday, October 29 5:00-7:30

PM

Critical Care: ICU Monitoring/Diagnostic Techniques, continued ROLE OF BRONCHOALVEOLAR LAVAGE IN PATIENTS WITH VENTILATOR-ASSOCIATED PNEUMONIA ON ANTIBIOTICS Chiara E. Conrado, MD ; RP Baughman- University of Cincinnati Medical Center, Cincinnati , Ohio, USA

THE "OPEN ABDOMEN" IS NOT A CONTRAINDICATION TO PRONE POSITIONI NG FOR SEVERE ARDS Henry J. Schiller, PM Rei lly, H L A nderson Ill, CW Schwab - University of Pennsylvania Medical Center Philadelphia, PA, USA

Purpose: Bronchoalveolar lavage has been useful but the yield has been reported t o be ow l in patients on prior antibiotics. In the Intensive Care Unit, nosocomial pneumonia usually occurs in patients with chronic purulent secretions and concurrent antibiotics. The purpose of this studywas to ide ntify t hose patients with ventilator-associated pneu monia w ho would benefit from a diagnostic BAL. Methods: Bronchoscopy records from our institution f or 111/87 to 10/31/95 were reviewed. Patients w ho underwent h ronchoscopy with BAL while on mechanical ventilation were selecte d. All BAL samples were handled using a previously described standardized technique introduced at ou r institution in 1985. Semiquantitative bacterial cult ures were conside red positive if they yielded > 10,000 C F U/ml BAL. Results: One hundred thirty-five patients were identified. Fifty-six (42%) had acquired immune deficiency syndrome (AIDS ). C hest film s were ecorded r for all patients. Results of microbiologic c ult ures and cytologic examination were available fo r 103 and results o fdifferential cell count fo r 104. Forty-one of 110 patients (37%) had a diagnostic BAL: Pne umocystis carinii pneumonia (PcP )-21; bacterial pneu monia- 14; Cytomegalovirus (CMV) pneumonia-10; fungal pneumonia-3; tuberculous-2; and atypical Mycobacteria-l (patients could have more than one diagnosis). Seven of 21 patie nts diagnosed with PeP had associated infections \vith other pathogens: C MV-6; M. tuberculous-1; and bacte1i a-1 (one patient was infected with 3 pathogens). Most patients were on prior antibiotics (85%), had purulent secretions (PM N >9) (76%) , and radiographic pattern consistent with pne umonia (96% ). The presence or absence of these factors did not predict a diagnostic BAL. Of 14 patients with bacte rial p neu monia, l l were on antibiotics, 1 was not, and this information was not available fo r 2. The yield of BALwas significantly higher in p taients with AIDS (59% vs 22%, p
Purpose: Prone positioning has been described as a maneuver by which oxygenation may be mproved i in t he patient with ARDS. Because of the fear of e'isceration, some clinicians have been reluctant to use this maneuver in trauma patients \vith "open abdomens ." It was our contention that these patients could be managed in the prone position without undue abdominal complications. Methods: \Ve reviewed the charts of 4 trauma patients w ith "open abdomens" who we managed in the prone position for ARDS and refractory hypoxemia. T he patients had u ndergone re cent laparotomy in which the skin and fascia of the abdomen w ere eft l open secondary to bowel ede ma. All of these patients were chemically paralyzed and mechanically ventilated. The a bdominal wound was dressed with a cotton surgical towel covered by a large Ioban® skin adhesive dressing which cove red the anterior t orso. All 4 p atients had severe ARD S, and remained hypoxic despite maximum conventional the rapy in the supine position. Results: The average age was 31.8 years (15 to 45 years), the mean admission APAC HE score was 25.5, and, at the time of p rone positioning, the mean Murray's Score was 3. 7. Three of the patients showed improvement in their hypoxemia "~ th a decrease in mean A-a gradient from 458 to 301 mm Hg. 2 o fthese patients eventually died ofmultiple o rgan fai lure. One patient with p rofound hypoxemia who had previously sustained a bradycardic arrest failed to im prove with this mane uver, and ultimately su ffered a second cardiac arrest while in the prone position. No evisceration, abdominal wound or abdominal viscera complications were note d as a result of prone positioning. Conclusions: With a secure adhesive dressing i n p ace, l p rone positioning can be used effectively in the patient with a n "open abdomen" without fear of evis-

VID EOSCOPIC PLACEMENT OF FEED ING TUBES: D EVELOPMENT OF A THROUGH THE TUBE TECHNIQUE Kurt W G rathwohl, MD; James W. Thompson, MD ; Bernard J. Roth, MD ; and Thom as A Dillard, MD ; Pulmonary Disease Se rvice, D e partme nt of Me dicine , Madigan Army Medical Cente r, Tacom a, W A 98431 USA

Purpose: To d escribe the d eve lopme nt of a be dside videoscopic tech nique for feeding tube placem ent using fibe roptics through the tube . Methods: Nine critically ill patie nts (6 males, 3 fem ales; 8 intubate d ) participate d in placem e nt of standard 10 Fre nch (3.3 mm) fe eding tubes. A total of 11 feeding tubes w e re placed into t h e small bowe l b y the oral (n=4) or nasal (n =7) route unde r direct visio n u sing a 6.7 French (2.2 mm ) fiberoptic scope through the fe eding tube. T ranspylo ric tube placem e nt was confinned videoscopically and radiographically. R e sults: Visually we advanced the fe eding tubes into the distal duod e num and b eyond in 8 atte mpts (73%) and into the second po rtion o f the duodenum in 3. The time require d f or placement ranged from 2 to 43minutes with a mean±standard de viation of 18 ± 12 m inutes. The fe eding tubes re m ained in place 10 ± 4 days and p atie nts m et their estimate d caloric need s \vithin 24 ho urs . Residues we re minimal and there were no docume nte d episod es of aspiration. Conclusions: This te chnique has the potential fo r rapid, accurate a n dsafe feeding tube placem ent. Clinical Imp lication s: Transpyloric small intestine fe eding tube placem ent can b e difficult and te dious. C u rrently accepte d techniques are associate d \vith disad vantages and risk. This te chnique has the potential to offe r clin icians a safe and rapid m eans with w hich t o place feeding tubes in p atie nts requiring nutritional support.

ceration.

C linical Implications: Trauma patients re present a severely injured patient population who may particularly benefit from aggressive therapy for ARDS because of their young age, good physiologic reserve, and the potentially reversible nature o f the ir pulmonary dysfunction. In these patients \\~th a large and secure adhesive abdominal dressing in place, the presence of an "open abdomen" should not limit the use of p rone positioning. Prone positioning may be a usefi.,J mane uver to improve o"ygenation in pati ents with severe ARDS.

ACCURACY OF D IRECT MEASUREMENT OF INJECTATE TEMPERATUREBYAPULMONARYARTERYCATHETER Steven Stites MD, *J. Barnes MD, J. Overman, P. O'Boynick MD University of Kansas Medical Center Kansas City, Kansas USA

Purpose: Accurate measurement of thermodilution cardiac output (CO) as defin ed by the Stewart-Hamilton equation depends upon calculation of injectate temperature (IT). A standard heat coefficient is used to estimate temperature c hanges from the point of measurement to the right atrium . Apulmonary artery catheter (PAC) has been designed with a thermistor moutlted in the right atrial injectate port to directly measure IT. \ Ve evaluated this mounted thermistor over a wide range of flow states and temperatures to de termine its respo nse characte ristics and accuracy.

Me thods: Initially, the mounted thermistor response time was evaluated by im mersion into a water bath at known temperature. The accuracy of the thermistor mounted on the PAC (B. Braun Dualthermistor RD3924) was then determined using a bench model. The catheter was immersed in a c irculating flow loop with known heat trallSfer characteristics. The ol op bath was kept at njectate i temperature. Accuracy wa_< tested witl1 ei ed, mid-range (10-15°C), and room temperature injectate. Results: The fi rst time constant for the thermistor mounted on the PAC was 180 msec. The accuracy data was determi ned from10 PACs in the circulating ol op using high, medium , and

lo\~1

flow states:

Di/J

lnjectate Temp Icc

0.19:!:0.09 0.06:!: 0.03 0.3 2 :!: 0.05

Midrange Room Te m p

Diff = Aventge diffe rence between bath temp corrected fo r thenna1 change in the ci rculating loop and measured IT

Conclusion : The thennistor mounted in t he right atrial port of the PAC had ade-

quate response ti me and dernonstrated accurate measurement of IT over a wide range

of flow and t emperature. Clinical Implications: Accurate measurement of IT is essential in detennining CO. Direct measurement of IT eliminates the need f ora thermal loss coefficient and should improve the accuracy and reproducibility of cardiac output in a broad range of clinical

states.

Supported b y a grant from B. Braun

1425

Abstracts of Original Investigations, CHEST 1996

Tuesday, October 29 5:00-7:30

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Critical Care: /CU Monitoring/Diagnostic Techniques, continued PULMONARY FUNCTION TESTS POST MEDIALIZATION FOR UNILATERAL VOCAL CORD PARALYSIS Frank Sorhage, R Barrera, D Kraus, D Stover. Department of Pulmonary Medicine, Memorial Sloan Kettering Cancer Center, New York, New York 10021 Purpose: To evaluate changes in pre and post operative pulmonary function tests and 02 % saturation in patients undergoing silastic cord medialization and to subjectively evaluate the quality of voice and cough. Methods: Patients with intrathoracic malignancies and unilateral vocal cord paralysis who underwent silastic vocal cord medialization were evaluated. Pulmonary function tests (PFTs) pre and post vocal cord medialization were performed. The variables evaluated were FEV1 (%pred), FEF50/ FIF50, FEFmax (%pred) and PIFR (US). The Flow Volume Loops (FVL) and 02% saturation were compared. A quality of voice and cough questionnaire was answered by the patients. Means were compared with t-test for paired samples. All data are presented as means±SD. Result.~: Ten consecutive patients requiring medialization were entered into the study. No statistically significant changes occurred in the parameters evaluated. Thirty percent of patients developed new FVL abnormalities after medialization consistent with either a variable or fixed extra thoracic upper airway obstruction (UAO). All patients had subjective improvement in their quality of voice and cough. FEVl (%pred)

FEF50/ FIF50

FEFmax (%pred)

PIFR (US)

PRE

65±24

83±65

55±16

2.92±0.98

POST

64±32

87±60

48±16

2.46±0.80

ConclusiOn: There IS no stgruficant change m PFT s after silastic vocal cord medialization. All of the patients had a subjective improvement in their quality of voice and cough. Clinical Impression: Successful amelioration of symptoms in all of the cases coupled with limited morbidity justifies treatment of this condition.

DOES COUGH NORMALLY CAUSE Sp02 TO FALL? Stephen Tan, B.Sc., and Arthur R Macneil, M.D. F.C.C.P. Faculty of Medicine, Dalhousie University, Halifax, Canada Purpose: Although precipitous falls in Sp02 with long recovery periods frequently accompany cough in those with cardiopulmonary impairment, the reaction of normal subjects to coughing is not well described. We attempted to determine the response of normal subjects to coughing. Methods: After observing the Sp02 for one minute, twelve healthy volunteers (mean age 26.8) were prompted to cough for intervals of 10, 20 and 30 seconds, the sequence being randomized. While coughing, the Sp02 was recorded every 2 seconds, and at lO second intervals for five minutes after coughing ceased. Results: During the lO sec. coughing spell 9 subjects desaturated. When coughing for 20 sec., 8 subjects showed desaturation, and 9 of the 12 desaturated during the 30sec. interlude. Although one subject desaturated to 6% less than baseline, the average fall in saturation was less than 1%. In the minute following cessation of cough, 10 subjects increased their Sp02 relative to baseline following a 10 sec. cough, 11 subjects increased their Sp02 following the 20 sec. and 30 sec. cough episodes. The average increase approached 1%. The consistency of the increase supports belief that the phenomenon is real. Conclusions: Although normal subjects frequently desaturate with cough the degree of change typically small and clinically negligible. There is an apparent increase in Sp02 during recovery from cough. Clinical Implications: Desaturation during coughing episodes is more typically viewed as a manifestation of disease.

INDICATORS OF LUNG ABNORMALITIES IN ACUTE SPINAL CORD INJURY Wilham T. Peruzzi, M.D.; M .L. Ault, M.D.; M.L. Franklin, M.D.; B.A. Shapiro, M.D.- Department of Anesthesiology, Northweste rn University Medical School, Chicago, IL 60611 Introduction: Using chest roentge nographs (CXR) to evaluate the presence of pulmonary abnonnahties is common practice. Bedside parameters such as vital capacity (VC) and negative inspiratory force (NIF) are used to assess respiratory reserves. We beheve a correlation should exist between measured ventilatory parameters and CXR abnonnahties. Methods: All unintubated patients admitted to the SCI intensive care unit over one year were studied. Daily meas urements of VC, forced expiratory pressure (FEP), and NIF were obtained for up to 5 days in enrolled patients. CXR's were obtained per ICU chnical protocols over the same time period and read by attending radiologists bhnded to the study. The average VC, FEP, and NIF values were then compared between the two roentgenographic groups classilled as either absence (CLR) or presence (POS) of atelectasis and/or infiltrate. Statistical analysis was then performed using an unpaired Student's t-test. Data from patients who demonstrated a change in their CXR from CLR to POS or POS to CLR were analyzed to determine the rehability of ventilatory parameters as a predictor of CXR changes. Results: Seventy-six patients with cervical and thoracic SCI were enrolled. A total of 123 CXR's were evaluated. There was a significant difference in mean VC, but not FEP or NIF, between the two roentgenographic groups (Table). Eight patie nts developed a cha nge in their CXR (CLR to POS; POS to CLR). These patients also demonstrated a significant change in their VC measurements (mean difference of 341 mL:t236, 95% C.I.) in association with the CXR changes. Conclusion: These data indicate that VC is a predictor of respiratory comphcations following acute SCI. Additionally, VC can be used as a clinical indicator of new or resolving roentgenographic abnonnahties in individual patients. VC is dependent upon both respiratory muscle function and functional lung parenchyma and is a sensitive indicator of pulmonary abnonnahties in acute SCI. X POS (n=35)

SD

xCLR (n=88)

SD

p-value

1400

:t531

1785

:t831

0.012

FEP

76

:t34

72

:t31

0.540

NIF

-84

:t41

-88

:t43

0.706

VC

Funding: U.S. Department of Education, NIDRR Grant #4133M-00008, Frankel Foundation.

INTERCHANGEABILITY OF PAIN MANAGEMENT SCALES FOR CRITICALLYILL CHILDREN Mary Lieh-Lai, MD; P. Simpson, PhD; R. Kauffman, MD; H. Uy, MD; M . Danjin, RN -Children's Hosp. of MI/Wayne State Univ, Det., MI, USA; Children's Mercy Hosp!Univ of Missouri, K.C. , MO, USA Purpose: The majority of children admitted to the intensive care unit (ICU ) post-operatively suffer moderate to severe pain. In order to institute treatment, objective pain measures are necessary. This can be difficult in children who are intubated and unable to cry or speak. We compared the Faces-Oucher (FO), self Oucher (SO), Children's Hospital of Eastern Ontario Pain Scale (CHEOPS) and the pressure aesthesiometer (PA) to assess correlation between scales, and if so, whethe r one scale can be used in place of another. Methods: Pain was assessed in 101 children age 3-18 yrs. admitted to the ICU for post-op care. Pain was measured serially after analgesic administration. Pain relief was defined as <60 (0-100) for SO in children '27 yr., <3 (0-5) for FO in those <7 yr., and <7 (4-13) for CH EOPS. Results: Agreement for Kappa statistics between the SO and CHEOPS was 0.38-0.74 (p<0.001 in all cases). However, despite this agreement, it would be incorrect to inte rchange the scales because even when scores were dichotomized at least 14% did not agree. The lack of agreement increased when the original scores were compared. This is best 1. illustrated in the scatter plot • Poinlleli.t (figure), where not only is 12 NoPainldief the re considerable scatter, but misclassification is evi~ i! 10 dent as well. The re was a tendency for P A scores to the agree more with CHEOPS in children <7 yr., but this correlation was not significant. R2=0.6M8 Conclusions: Although s me correlation 120 the re is o 100 80 60 20 ·20 between the Oucher and CHEOPS when measuring pain, the substitution of one pain scale for the other may lead to inaccurate conclusions regarding pain relief. Clinical Implications: When measuring pain, caregivers should not substitute one pain scale for another during the assessment period since this may lead to misinterpretation of the degree of pain and may result in inappropriate pain management. Supported by The Ronald McDonald Children's Charities and NICHD grant #HD31313.

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