David H. Wong

Factors associated with postoperative pulmonary complications in patients with severe chronic obstructive pulmonary disease.

The purpose of this study was to determine the incidence of different postoperative pulmonary complications (PPCs) and their associated risk factors in patients with severe chronic obstructive pulmonary disease (COPD) (forced expiratory volume in 1 s [FEV1] <or=to1.2 L and FEV1/forced vital capacity (FVC) <75%) undergoing noncardiothoracic operations. Thirty-nine of 105 patients (37%) had one or more PPCs (death, pneumonia, prolonged intubation, refractory bronchospasm, or prolonged intensive care unit (ICU) stay). Thirty-eight of 39 patients (97%) with a PPC had an anesthetic duration >2 h. Our study patients had a 47% 2-yr mortality rate. We determined specific risk factors for each PPC by analyzing potential preoperative and intraoperative risk factors. Pulmonary factors alone do not predict the likelihood of PPCs in severe COPD patients. Multiple logistic regression identified composite scoring systems, such as the ASA physical status, as the best preoperative predictors of PPCs, probably because they include both pulmonary and nonpulmonary factors. During the intraoperative period, avoiding general anesthesia with tracheal intubation may decrease the risk of postoperative bronchospasm. Shortening the duration of surgery and anesthesia may decrease the risk of prolonged ICU stay. (Anesth Analg 1995;80:276-84)

Changes in intensive care unit nurse task activity after installation of a third-generation intensive care unit information system

ObjectiveTo determine the percentage of time that intensive care unit (ICU) nurses spend on documentation and other nursing activities before and after installation of a third-generation ICU information system. DesignProspective data collection using real-time time-motion analysis, before and after installation of the ICU information system. SettingA ten-bed surgical ICU at a Veterans Affairs medical center. SubjectsICU nurses. InterventionsInstallation of a third-generation ICU information system. Measurements and Main ResultsTen ICU nurses were studied before and after installation of the ICU information system. Each ICU nurse’s activities and tasks, during 4-hr observation periods, were categorized in real-time by a nurse observer and recorded in a laptop computer. Each recorded task was automatically time-stamped and logged into a data file. The percentage of time spent on documentation decreased from 35.1 ± 8.3% to 24.2 ± 7.6% (p = .025) after the ICU information system was installed. The percentage of time providing direct patient care increased from 31.3 ± 9.2% to 40.1 ± 11.7% (p = .085). The percentage of time doing patient assessment, a direct patient care task, increased from 4.0 ± 4.7% to 9.4 ± 4.4% (p = .001). ConclusionsInstallation of a third-generation ICU information system decreased the percentage of time ICU nurses spent on documentation by >30%. Almost half of the time saved on documentation was spent on patient assessment, a direct patient care task.

Noninvasive Cardiac Output: Simultaneous Comparison of Two Different Methods with Thermodilution

The authors attempted to simultaneously measure cardiac output by thermodilution (COtd), thoracic bioimpedance (CObi), and suprasternal Doppler ultrasound (COdopp) in 68 patients. Subgroups separately compared included patients whose lungs were mechanically ventilated, patients undergoing cardiac surgery, aortic surgery, patients with dysrhythmias, and patients with sepsis. The authors also studied the value of the ventricular ejection time (VET) in evaluating the agreement of CObi and COdopp with COtd. Simultaneous CObi and COtd were available in a total of 56 patients (416 data sets) with an overall correlation coefficient r = 0.61, regression slope (m) of 0.52, intercept (y) of 2.46, and mean (CObi-COtd) difference (bias) of -0.67 +/- 1.72 (SD) l/min. Simultaneous COdopp and COtd were available in 59 patients (446 data sets) with an overall r = 0.51, m of 0.53, y of 2.05, and bias of -0.79 +/- 1.95 l/min. CObi agreed most closely with COtd in patients whose lungs were mechanically ventilated, who had not undergone cardiac or aortic surgery, and with VET difference less than 40 ms (16 patients, 99 data sets; r = 0.74; m = 0.97; y = 0.15; bias = -0.02 +/- 1.53 l/min). COdopp agreed most closely with COtd in patients whose lungs were mechanically ventilated, who had not undergone cardiac or aortic surgery, and in sinus rhythm with VET difference less than 40 ms (10 patients, 45 data sets; r = 0.82; m = 0.98; y = -0.07; bias = -0.82 +/-1.03 l/min). VET by radial artery can help evaluate the reliability of CObi and COdopp.

Nasal colonization with methicillin-resistant Staphylococcus aureus on admission to the surgical intensive care unit increases the risk of infection.

We prospectively studied the relationship of perioperative methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization and subsequent infection in surgical intensive care unit (SICU) patients. In addition, risk factors for MRSA nasal colonization were examined. All patients admitted to the 15-bed SICU between August 1991 and July 1992 had their anterior nares cultured. Cultures positive for S. aureus were subsequently placed on oxacillin-containing plates to screen for methicillin-resistance. Of 484 patients, 19 had MRSA nasal colonization (3.9%). There were five infections in the 19 patients with positive perioperative nasal cultures versus six infections in the remaining 465 patients (P < 0.0001). Immunoblot typing confirmed the concordance of colonizing and infecting strains. Prior exposure to the spinal cord injury center (P < 0.001) and prior antibiotic therapy (P < 0.003) were also significant multivariate risk factors for perioperative nasal colonization. Patients with perioperative MRSA nasal colonization are at significantly increased risk of subsequent postoperative MRSA infection.

Changes in cardiac output after acute blood loss and position change in man

Thoracic bioimpedance cardiac output (Qtbi) was measured at 1-min intervals in 27 volunteers before, during, and after withdrawing 500 ml (3.7 to 8.5 ml/kg; mean 5.8) of blood. The effects of passive leg raising (PLR) and standing on Qtbi were measured before and after blood withdrawal. Arterial oxygen saturation (SaO2), transcutaneous oxygen tension (PtcO2), mean arterial BP (MAP), and heart rate (HR) were also measured before and after blood withdrawal. Thoracic bioimpedance cardiac index (CI) decreased 18% (0.8 +/- 0.1 L/min.m2, p less than .0001) and stroke volume index (SI) decreased 22% (14.8 +/- 2.7 ml/beat.m2, p less than .0001) after blood withdrawal. HR, MAP, SaO2, and PtcO2 were not significantly different after blood withdrawal. Before blood withdrawal PLR increased CI 6.8% (0.3 +/- 0.1 L/min.m2, p less than .0001); after blood withdrawal PLR increased CI 11.1% (0.4 +/- 0.1 L/min.m2, p less than .0001). PLR can increase stroke volume and cardiac output in hypovolemic humans.

Acute cardiovascular response to passive leg raising

Cardiac output by thoracic bioimpedance, heart rate, BP, oxygen saturation, and transcutaneous oxygen tension were measured at 1-min intervals in 45 patients before and after passive leg raising (PLR). Mean cardiac index increased only 0.09 ± 0.02 (SEM) L/min ċ m2 (p < .001), mean transcutaneous oxy

Comparison of changes in transit time ultrasound, esophageal Doppler, and thermodilution cardiac output after changes in preload, afterload, and contractility in pigs

The purpose of this study was to compare how well changes in cardiac output (CO) measured by esophageal Doppler (Doppler) and thermodilution (TD) followed changes in CO measured by transit time ultrasound (TTU). Simultaneous Doppler, TD, and TTU measurements of CO were made before and after changes in preload, afterload, or contractility in seven piglets. Mean changes in each CO method for each type of change in CO were compared by analysis of variance. Changes in TTU CO, TD CO, and Doppler CO were compared by correlation, linear regression, and bias and precision statistics.Of 86 TTU changes in CO > 10%, Doppler changed the same direction as TTU 59 times, changed in an opposite direction 6 times, and changed > 10% 21 times. Thermodilution changed in the same direction as TTU 72 times, in the opposite direction 4 times, and changed < 10% 10 times.Changes (%Δ) in TTU and TD measurements of CO were not significantly different in any group. Changes in Doppler CO and TTU CO were different for two afterload and contractility groups. Percent changes in Doppler CO had a correlation coefficient (r) = 0.74, m = 0.72, and bias (mean % Δ Doppler CO - mean %Δ TTU CO) = 6.3 ± 29.7 with % Δ TTU CO. Percent changes in TD CO had an r = 0.90, m = 0.92, and bias = 5.7 ± 19.1 with %Δ TTU CO. Cardiac output measured by Doppler underestimated changes in CO due to changes in preload and contractility and exaggerated changes in CO due to changes in afterload.

Incidence of perioperative myocardial ischemia in TURP patients

STUDY OBJECTIVE To determine the incidence of new episodes of myocardial ischemia in patients undergoing transurethral resection of the prostate (TURP). DESIGN Prospective, nonrandomized study. SETTING Veterans Administration medical center. PATIENTS 39 patients undergoing elective TURP. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Myocardial ischemia was detected with a 3-channel ambulatory ECG recorded. The ambulatory ECG recorder was applied preoperatively and removed when the patient left the recovery room. New myocardial ischemia was defined as a 1 mm or greater ST depression or a 2 mm or greater ST elevation from baseline, lasting for 1 minute or longer in at least one lead at the J point plus 60 msec unless this point fell within the T wave, in which case the J point 40 msec or greater was used. ST changes consistent with myocardial ischemia were confirmed by a cardiologist blinded to the patients clinical course. Seven of 39 TURP patients (18%) had ST segment changes indicative of new myocardial ischemia. These seven patients had more prostate tissue resected and more blood loss than the 32 patients who did not have any myocardial ischemia (p < 0.05). CONCLUSIONS Patients undergoing TURP have an 18% incidence of myocardial ischemia. Patients undergoing TURP with more prostate tissue resected and greater blood loss are at increased risk for perioperative myocardial ischemia.

Changes in renal vein, renal surface, and urine oxygen tension during hypoxia in pigs

AbstractTo determine whether ureteral urine oxygen tension could serve as a monitor of renal hypoxia and its relationship to other renal O2 tension parameters, we simultaneously measured femoral artery (PaO2), renal vein (Pr