Changes in pulmonary mechanics after fiberoptic bronchoalveolar lavage in mechanically ventilated patients

We describe perinatal findings in a female fetus with partial trisomy 8q(8q24.1-->8qter) and partial monosomy 15q(15q26.1-->15qter) resulting from a paternal t(8;15) reciprocal translocation. Prenatal sonographic examination showed intra-uterine growth retardation, bilateral ventriculomegaly, cardiomegaly with arrhythmia, anhydramnios, and absent kidney and urinary bladder images. The pregnancy was terminated at 28 weeks of gestation. At birth, the infant manifested typical dysmorphic features of partial trisomy 8q. Necropsy further revealed hydrocephalus, congenital diaphragmatic hernia, ventricular septal defect, a horseshoe kidney with renal hypoplasia, and kyphoscoliosis. Our case shows that the coexistence of partial trisomy 8q24.1-->8qter and partial monosomy 15q26.1-->15qter are more detrimental than either defect alone and can result in a complex of major malformations. Prenatal ultrasound examination and cytogenetic assessment should be offered in subsequent pregnancies.     

Effects of intravenous medium-chain triglycerides on pulmonary gas exchanges in mechanically ventilated patients

OBJECTIVE: In mechanically ventilated patients, pulmonary gas exchange was investigated during the administration of total parenteral nutrition containing medium-chain triglycerides or long-chain triglycerides as fat emulsions. DESIGN: Prospective, randomized, crossover trial (two lipid infusion periods of 8 hrs). SETTING: Intensive care unit in a university hospital. PATIENTS: Six mechanically ventilated patients, using the pressure-support mode. INTERVENTIONS: Total caloric intake was adapted according to measured energy expenditure. Fat emulsion provided 50% of the energy expenditure. Patients were infused with 50% medium-chain/50% long-chain triglycerides or 100% long-chain triglycerides in a random sequence. MEASUREMENTS AND MAIN RESULTS: Oxygen consumption, CO2 production, and minute ventilation were measured by indirect calorimetry. PaO2 and PaCO2 were determined in blood samples. Medium-chain triglycerides increased oxygen consumption by 27.8% and minute ventilation by 14.3% at the end of the protocol. CO2 production, PaO2, and PaCO2 were not different between groups. CONCLUSIONS: Medium-chain triglycerides cause an increase in metabolic demand in mechanically ventilated patients when they are infused over a short period. Postoperative or intensive care unit patients with a low pulmonary reserve should receive infusions of medium-chain triglycerides over a more prolonged period than long-chain triglycerides.     

Assessment of ventilation-perfusion mismatching in mechanically ventilated patients

The multiple inert gas elimination technique (MIGET) is a robust tool to assess both ventilation-perfusion (V'A/Q') distributions and the role of extrapulmonary factors determining arterial oxygenation during spontaneous breathing and in mechanically ventilated patients. Mixed expired gas sampling used in the MIGET is most often obtained from a 10-L mixing box (10L-MB) placed in the expiratory side of the ventilator circuit. Consequently, a considerable increase in the compression volume (Vc) would be expected which, in turn, can give rise to potential errors in the estimation of the effective tidal volume delivered to the patient. The effects of the 10L-MB on the Vc were compared with those produced by a newly designed 1-L, mixing box (IL-MB). At a given peak pressure (Ppeak) within the ventilator circuit, the Vc generated by the 10L-MB was about six-times higher than that produced by the 1L-MB. At a Ppeak =50 cmH2O, the Vc were 377 mL (10L-MB) and 67 mL (1L-MB) (p<0.001). In six patients, the mixed expired partial pressures of the six inert gases simultaneously collected from the two mixing boxes fell on the identity line. V'A/Q' distributions recovered using each of the two mixing boxes were equivalent. With the IL-MB, the effects of different positive end-expiratory pressure levels (0, 6 and 12 cmH2O) on Vc and arterial carbon dioxide tension were negligible. In conclusion, the new 1-L mixing box provides efficient gas mixing and substantially decreases the compression volume. It is, therefore, recommended when studies requiring mixed expired gas are performed in ventilated patients.     

Radiographic estimation of intracuff pressure in mechanically ventilated patients

We evaluated the usefulness of roentgenographic tracheal tube cuff shadow to tracheal wall diameter ratio (CTW ratio) and cuff minus tracheal diameter difference (C-T diameter) in estimating intracuff pressure (ICP) in intubated and mechanically ventilated patients. Seventy-one measurements of ICP, CTW ratio and C-T diameter were obtained from 20 mechanically ventilated male patients intubated with high volume low pressure cuffs in the surgical and medical intensive care units. The mean age was 61 years (range 30 to 83 years). ICP was measured by one observer, while CTW ratio and C-T diameter was measured by another observer. No significant relationship was seen between ICP and CTW ration (r = 0.092, p = 0.873), or between ICP and C-T diameter (r = 0.093, p = 0.42) by linear regression analysis. In conclusion, roentgenographic estimation of ICP by portable plain chest films in intensive care units was not found useful in this study.     

Small airway closure and positive end-expiratory pressure in mechanically ventilated patients with chronic obstructive pulmonary disease

The effects of positive end-expiratory pressure (PEEP) on alveolar recruitment and closing volume were studied in ten supine, sedated, and paralyzed patients with chronic obstructive respiratory disease and acute respiratory failure. We applied PEEP (0, 5, 10, and 15 cm H2O) and constructed inflation static volume-pressure (V-P) curves. In all patients, the static V-P curves obtained at different PEEP levels were superimposed on each other, indicating that with PEEP there was no recruitment of previously atelectatic lung units. However, the static V-P curves exhibited an inflection point, which should reflect the critical pressure (Po) required to reopen all closed airways, whilst the corresponding lung volume (Vo) reflects the opening volume. On average, Vo was 0.71 L above the relaxation volume of the respiratory system (Vr). All patients, however, exhibited dynamic hyperinflation, i.e., with zero PEEP (ZEEP) the end-expiratory lung volume (EELV) was 0.54 L above Vr. Nevertheless, in seven patients the EELV on ZEEP was below Vo, resulting in cyclic reopening and closure of small airways with each breathing cycle, with concomitant mechanical stresses on the peripheral airways that may lead to low-volume barotrauma. Such barotrauma may be prevented by increasing with PEEP the EELV to Vo.     

Concealed lung abscess in critically ill, mechanically ventilated patients

This article reports on phenomenological research designed to discover how caring was taught in a nursing education program. The basic questions were: 1) What is the meaning of caring to the faculty and students; 2) How do the faculty communicate this meaning to the students; and 3) How does this meaning shape the experience of the students? Data were collected from a small associate degree nursing program using: a) semi-structured interviews with all faculty and a selected group of students, b) classroom observations, and c) review of documents. Data were analyzed for and found to have content explaining the meaning of caring, how caring was being taught, and what students were learning about caring as the essence of nursing. Implications derived speak to the need for faculty and administrators to have caring as a way of being if they wish to communicate caring as the essence of nursing to students.     

Flow resistance in mechanically ventilated patients with severe neurological injury

In 5 mechanically ventilated patients with severe neurological injury (SNI), we measured the respiratory system's flow resistance (Rrs) over a range of inspiratory flows between 0.2 to 2 L/s, at inflation volumes (delta V) ranging from 0.1 to 1 L. Under baseline ventilatory conditions (V = 1 L/s; delta V = 0.95 L), we also partitioned Rrs into airway resistance (Raw) and the additional resistance offered by the tissues of the lung and chest wall (delta Rrs). At all inflation volumes, Rrs decreased hyperbolically with increasing flow but was higher than in normal anesthetized paralyzed subjects (N). At V of 1 L/s and delta V of 0.5 L, Rrs was significantly greater in SNI than in N (7.7 +/- 1.5 v 4.2 +/- 0.5 cm H2O/L/s; P < .01). This discrepancy was due to higher Raw in SNI. Indeed, at V of 1 L/s, Raw (mean +/- SEM) was significantly higher in SNI than in N (4.0 +/- 0.9 v 2.4 +/- 0.2 cm H2O/L/s; P < .001), whereas delta Rrs did not differ significantly. The increased Raw in SNI was due to the fact that these patients were therapeutically hyperventilated (PaCO2 = 30.4 +/- 4.2 mm Hg) and as a result their airways were bronchoconstricted. We conclude that in the intensive care unit setting, hyperventilated patients with severe neurological injury can not be considered to be adequate controls in terms of Rrs and Raw, because hypocapnia induces an increase of Raw and consequently also in Rrs (= Raw+delta Rrs).     

Impaired gastric emptying in mechanically ventilated, critically ill patients

OBJECTIVE: To measure gastric emptying in critically ill patients using an acetaminophen absorption model and determine which variables are associated with impaired gastric emptying. DESIGN: A prospective, cohort study. SETTING: A medical/surgical ICU at a tertiary care hospital: Hamilton General Hospital, Hamilton, Ontario. PATIENTS AND PARTICIPANTS: We recruited 72 mechanically ventilated patients expected to remain in the ICU for more than 48 h. Our results were compared to those in healthy volunteers. INTERVENTION: Within 48 h of admission to the ICU, 1.6 g acetaminophen suspension were administered via a nasogastric tube into the stomach. Blood samples were drawn a t = 0, 30, 60, 90, and 120 min for measurement of plasma acetaminophen levels determined by the enzymatic degradation method. MEASUREMENTS AND RESULTS: Maximal concentration of acetaminophen was 94.1 (75.3) mumol/l compared to 208.4 (33.1) mumol/l in a control population (p < 0.0001). The time to reach the maximal concentration was 105 min (60-180) compared to 30 min (15-90) in controls (p < 0.0001). The area under the time-acetaminophen concentration curve t = 120 was 9301 (7343) mumol/min per l compared to 11644 (1336) mumol/min per l in the controls (p = 0.28). The variables associated with delayed gastric emptying were age, sex and use of opioids for analgesia and sedation. CONCLUSIONS: Gastric emptying is delayed in critically ill patients. The important consequences of this phenomenon include intolerance to enteral nutrition and gastric colonization. Strategies to minimize the use of narcotics may improve gastric emptying. Studies to examine the effect of gastrointestinal prokinetic agents on gastric emptying are needed.     

Effects of tracheal suctioning on respiratory resistances in mechanically ventilated patients

OBJECTIVE: To evaluate the effects of tracheal suctioning (TS) on respiratory resistances in sedated critical care patients receiving mechanical ventilation (MV). SETTING: Surgical ICU of Bichat Hospital, Paris. PATIENTS AND PARTICIPANTS: Thirteen sedated critical care patients receiving MV for various conditions. MEASUREMENTS AND RESULTS: Airway resistances (R1), airway and pulmonary resistances (R2), and intrinsic positive end-expiratory pressure (PEEPint) were measured according to the end-inspiratory and end-expiratory occlusion methods before and after TS. R1 and R2 increased by 49.1% and 46.3%, respectively, 0.5 min after TS (p<0.01) but returned to baseline values at 1 min without any change thereafter. PEEPint decreased progressively following TS to reach a significant level (-13.3%) at 10 min (p<0.05) and was persistently reduced at 30 min (p<0.01). Nine patients received 500 microg of inhaled albuterol before another suctioning procedure. R1 and R2 decreased by 11.5% and 9.9%, respectively, 20 min after inhalation (p<0.05), but the R1 and R2 initial increase following TS did not differ between the two suctioning procedures. CONCLUSIONS: TS evokes only a transient bronchoconstrictor response, but thereafter, does not reduce respiratory resistances below presuctioning values. However, the decrease of PEEPint following TS suggests an increase of expiratory flow. Effective beta2-adrenergic receptor blockade fails to suppress the TS-induced bronchoconstrictor response.     

Ultrasonographic bedside evaluation of maxillary sinus disease in mechanically ventilated patients

GABA modulates dopamine concentrations in the nucleus accumbens and corpus striatum. Using in vivo microdialysis techniques we examined this modulatory role and the extent to which three different GABAergic drugs can attenuate cocaine's ability to increase extracellular dopamine concentrations and gross locomotor activity. Ethanol, lorazepam (Ativan), and gamma-vinyl GABA (GVG) significantly and dose-dependently attenuated cocaine-induced dopamine release in the corpus striatum of freely moving animals. Unlike ethanol or lorazepam, however, GVG is not a sedative hypnotic in the doses used, and hence the strategy of selectively increasing GABAergic activity by suicide inhibition of the catabolic enzyme, GABA-transaminase, offers the unique advantage of attenuating cocaine-induced dopamine release without the apparent side effects typically associated with sedative hypnotics.     

Effects of extrinsic positive end-expiratory pressure on mechanically ventilated patients with chronic obstructive pulmonary disease and dynamic hyperinflation

OBJECTIVE: To examine the circulatory and respiratory effects of extrinsic positive end-expiratory pressure (PEEPe) in patients with chronic obstructive pulmonary disease (COPD) and dynamic hyperinflation during controlled mechanical ventilation. DESIGN: Different levels of PEEPe were applied randomly in mechanically ventilated patients with COPD and dynamic hyperinflation. SETTING: Respiratory Intensive Care Unit of a University Hospital. PATIENTS: 9 patients with acute respiratory failure and dynamic hyperinflation due to acute exacerbation of COPD. INTERVENTIONS: PEEPe 35%, 58% and 86% of intrinsic PEEP (PEEPi) were applied. MEASUREMENTS AND RESULTS: Using flow-directed pulmonary artery catheters hemodynamic measurements were obtained, while simultaneously lung volumes, airflows and airway pressures were recorded. In order to estimate alveolar pressures (Palv), rapid airway occlusions during passive expiration were also performed. At no level of PEEPe were significant changes in cardiac output, gas exchange variables, dead space, airways inflation resistances and respiratory system static end-inspiratory compliance observed. At high level of PEEPe central venous, mean pulmonary arterial and pulmonary capillary wedge pressures were increased significantly. All but one patient were flow-limited during passive expiration. PEEPe 86% of PEEPi caused a significant increase in end-expiratory lung volume and total PEEP. Iso-volume pressure-flow curves showed volume-dependence expiratory flow limitation in 2 patients, while in 8 patients volume-dependence of critical driving pressure (Palv-mouth pressure) that decreased flows was also observed. CONCLUSIONS: The effects of PEEPe on iso-volume flow and hence on lung mechanics and hemodynamics, depend on many factors, such as airways resistances, lung volumes and airway characteristics, making the patient response to PEEPe unpredictable.     

Quantification of aortic stenosis in mechanically ventilated patients using multiplane transesophageal Doppler echocardiography

OBJECTIVE: The development of sudden postoperative hearing loss as a complication of microvascular decompression (MVD) operations in the cerebellopontine angle has already been reported. A sudden hearing loss of vascular origin may also occur hours or days after such operations, but even in such cases an improvement of hearing over the following weeks is possible. Here we report on a gradual deterioration of hearing over a period of two weeks after MVD which has not been described in the literature up to now. CLINICAL PRESENTATION: A MVD operation was performed twice on a 36 year old patient with trigeminal neuralgia. After the second operation the patient developed a slight hearing impairment 3 days postoperatively which increased over a period of two weeks and ended up with total deafness. The course of intra-operative brainstem auditory evoked potentials and postoperative audiograms is documented. CONCLUSION: Because of gradual development of the delayed hearing loss, we conclude that postoperative tissue scarring may be the underlying pathology.     

Gastric intramucosal acidosis in mechanically ventilated patients: role of mucosal blood flow

To examine the roles of Arg-vasopressin (AVP)- and vasoactive intestinal peptide (VIP)-containing neurons in the suprachiasmatic nucleus (SCN) in production of circadian rhythmicity of locomotor activity, variations in the contents of AVP and VIP in punched-out SCN tissue and locomotor activity were measured under a light-dark cycle as well as under conditions of constant light for up to 3 weeks. Under the light-dark cycle, contents of AVP and VIP, and locomotor activity showed marked circadian rhythmicity. Under constant light, AVP content showed circadian rhythmicity until 3 weeks, while VIP rhythm disappeared from the first week with decreases in its content. Locomotor activity showed a free-running circadian rhythm for more than 3 weeks under constant light conditions in most cases. These results suggest that AVP but not VIP in the SCN may be involved in the generation of locomotor activity rhythm under conditions of constant light.     

Topical antimicrobial prophylaxis of nosocomial pneumonia in mechanically ventilated patients. Microbiological observations

Generally, reduction of colonization and infection with potentially pathogenic microorganisms in intensive care units (ICU) is attempted by a combination of antimicrobial agents administered topically in the digestive tract and systematically. We tested the efficacy of topical antimicrobial prophylaxis of the oropharynx and stomach administered in combination with sucralfate without systemic prophylaxis in 25 mechanically ventilated ICU patients. The regimen successfully reduced colonization with potentially pathogenic microorganisms in the oropharynx and trachea without modifying the intestinal flora. However, colonization and infections with gram-positive cocci and gram-negative rods other than Enterobacteriaceae and Pseudomonadaceae and resistant to one or both the antimicrobial agents used were observed.     

Characteristics of airway colonization in mechanically ventilated newborn infants

A predominant mutation within the BRCA1 predisposition gene, 185delAG, has been detected in about 1% of the Ashkenazi population, considered a high-risk group for breast and ovarian cancers. We examined 639 unrelated healthy Jews of Iraqi extraction, a presumed low-risk group, for the existence of this mutation. Three individuals were identified as 185delAG mutation carriers, and haplotype analysis of the Iraqi mutation carriers revealed that 2 of the Iraqis shared a common haplotype with 6 Ashkenazi mutation carriers, and 1 had a haplotype which differed by a single marker. This study suggests that the BRCA1 185delAG mutation also occurs in populations considered at low-risk for breast and ovarian cancers, and that it might have occurred prior to the dispersion of the Jewish people in the Diaspora, at least at the time of Christ.     

Efficacy of dead-space washout in mechanically ventilated premature newborns

The prosthetic dead space makes a significant contribution to the total dead space in low-birth-weight premature newborns receiving artificial ventilation in response to respiratory distress. Use of an endotracheal tube with capillaries molded into the tube wall enables washout of the dead space without insertion of a tracheal catheter. In 10 premature newborns (mean gestational age, 27.5 +/- 2.2 wk; mean weight, 890 +/- 260 g) receiving continuous positive-pressure ventilation (Paw = 12.7 +/- 1.8 cm H2O; FIO2 = 39 +/- 17%), tracheal gas insufflation (TGI) for CO2 washout was conducted using this technique. The flow of tracheal insufflation (0.5 L/min) was derived from the inspiratory line of the ventilator circuit and blown into the trachea. Intratracheal pressures showed little or no TGI-related modification ( < 1 cm H2O). A control system enabled TGI discontinuation in the event of a pressure rise. At constant ventilation pressure, PaCO2 decreased by 12.1 +/- 5.9 mm Hg (delta PaCO2 = -26 +/- 12%) under TGI, whereas PaO2 remained unchanged. While maintaining PaCO2 constant, peak inspiratory pressure (PIP) was decreased by 5.4 +/- 1.7 cm H2O (delta PIP = -22.0 +/- 8.3%). TGI showed immediate efficacy (PCO2 reduction of at least 5 mm Hg) in nine of the 10 newborns who then received chronic TGI (14 to 138 h). TGI appears to be an effective method, suitable for long-term clinical application, enabling a reduction in the aggressive nature of conventional ventilation.     

Formulaic methods of estimating calorie requirements in mechanically ventilated obese patients: a reappraisal

We reviewed 410 cases, 365 males and 45 females, mean age 64 years, of inguinal and femoral hernia, from 1/1/1991 to 31/12/1994, repaired with Lichtenstein and Trabucco techniques. Recurrent hernias repaired were 36 (8,8%). Local anesthesia was used in 82% and follow-up has ranged from 6 months to 4 years. The meshes used are made with a single layer of polipropylene and the Trabucco plugs T1 were made by hand at the operating table. In our experience these two techniques are simple, but is very important, before application of the mesh, a correct dissection of inguinal region. We made a complete excision of cremasteric fibers preservig, if possible, the genital branch of the genitofemoral nerve. The transversalis fascia is introflected and sutured in direct hernia repair or when there are a loss of tissues. The preliminary results obtained with the "tension free" hernioplasty are satisfying. The most important complications were 9 hematomas and an important and persistent inguinal neuralgia in 1 case. There were no recurrences, but we must considered the short follow-up period.     

Exposure to chlorine gas: effects on pulmonary function and morphology in anaesthetised and mechanically ventilated pigs

We report on a child with a 'new' syndrome characterized by multiple congenital anomalies, mental retardation, sensorineural deafness, talon cusps of upper central incisors, growth retardation, bilateral symmetrical digital anomalies mainly in the form of preaxial brachydactyly and hyperphalangism of digits I-III. Because he had a similarly affected brother and his parents were cousins we suggest autosomal recessive inheritance, X-linked recessive inheritance cannot be excluded. Differential diagnosis from other syndromes with preaxial brachydactyly and hyperphalangism is presented.     

Clinical examination reliably detects intrinsic positive end-expiratory pressure in critically ill, mechanically ventilated patients

Critically ill patients requiring mechanical ventilation often develop intrinsic positive end-expiratory pressure (PEEPi). Methods for its detection include an expiratory flow waveform display (not always available), an esophageal pressure transducer (invasive), or a relaxed or paralyzed patient. We sought to determine the accuracy of clinical examination for detecting PEEPi. Examiners blinded to waveform analysis assessed patients for the presence of PEEPi by inspection/palpation and auscultation. If either inspection/palpation or auscultation demonstrated PEEPi, it was said to be present by clinical exam. Clinicians with various levels of experience (attending, resident, student) made 503 observations of 71 patients. Sensitivity (SENS), specificity (SPEC), positive predictive value (PPV), negative predictive value (NPV), and likelihood ratios were determined for inspection/palpation, auscultation, and clinical exam. PEEPi was present during 69.8% of observations. SENS, SPEC, and PPV of clinical exam were 0.72, 0.91, and 0.95 respectively for the examiners as a whole. Likelihood ratio for PEEPi detection by clinical exam was 8.35. Attending intensivists displayed SPEC and PPV of 1.0. NPV was only 0.58 (likelihood ratio 0.31). We conclude that the clinical exam is very good for detecting PEEPi at all experience levels; and further, that the clinical exam is only modestly useful for ruling out PEEPi, therefore, other tests should be used if PEEPi is not detected by clinical exam.