Humidification performance of two high-flow nasal cannula devices: a bench study

INTRODUCTION

Delivering heated and humidified medical gas at 20-60 L/min, high-flow nasal cannula (HFNC) creates low levels of PEEP and ameliorates respiratory mechanics. It has become a common therapy for patients with respiratory failure. However, independent measurement of heat and humidity during HFNC and comparison of HFNC devices are lacking.

METHODS

We evaluated 2 HFNC (Airvo 2 and Optiflow system) devices. Each HFNC was connected to simulated external nares using the manufacturer's standard circuit. The Airvo 2 outlet-chamber temperature was set at 37°C. The Optiflow system incorporated an O2/air blender and a heated humidifier, which was set at 40°C/3. For both systems, HFNC flow was tested at 20, 40, and 50 L/min. Simulating spontaneous breathing using a mechanical ventilator and TTL test lung, we tested tidal volumes (VT) of 300, 500, and 700 mL, and breathing frequencies of 10 and 20 breaths/min. The TTL was connected to the simulated external nares with a standard ventilator circuit. To prevent condensation, the circuit was placed in an incubator maintained at 37°C. Small, medium, and large nasal prongs were tested. Absolute humidity (AH) of inspired gas was measured at the simulated external nares.

RESULTS

At 20, 40, and 50 L/min of flow, respective AH values for the Airvo 2 were 35.3 ± 2.0, 37.1 ± 2.2, and 37.6 ± 2.1 mg/L, and for the Optiflow system, 33.1 ± 1.5, 35.9 ± 1.7, and 36.2 ± 1.8 mg/L. AH was lower at 20 L/min of HFNC flow than at 40 and 50 L/min (P < .01). While AH remained constant at 40 and 50 L/min, at 20 L/min of HFNC flow, AH decreased as VT increased for both devices.

CONCLUSIONS

During bench use of HFNC, AH increased with increasing HFNC flow. When the inspiratory flow of spontaneous breathing exceeded the HFNC flow, AH was influenced by VT. At all experimental settings, AH remained > 30 mg/L.

[Vocal cord paralysis associated with tracheal intubation: incidence, risk analysis, and classification of severity]

Vocal cord paralysis after tracheal intubation is rare. It causes severe hoarseness and aspiration, and delays recovery and discharge. Arytenoid cartilage dislocation and recurrent nerve paralysis are main causes of vocal cord paralysis. Physical stimulation of the tracheal tube as well as patient and surgical characteristics also contribute. Vocal cord paralysis occurs in 1 (0.07%) of 1,500 general surgery patients and on the left side in 70% of cases. It is associated with surgery/anesthesia time (two-fold, 3-6 hours; 15-fold, over 6 hours), age (three-fold, over 50 years), and diabetes mellitus or hypertension (two-fold). Symptoms resolve in 2-3 months. In adult cardiovascular surgery, vocal cord paralysis occurs in 1 (0.7-2%) of 50-100 cardiac surgery patients and 1 (8.6-32%) of 3-10 thoracic aortic surgery patients. In pediatric cardiac surgery, vocal cord paralysis occurs in 1 (0.1-0.5%) of 200-1,000 patients. We classified the severity of vocal cord paralysis as I, severe hoarseness; II, aspiration or dysphagia; and III, bilateral vocal cord paralysis, aspiration pneumonia, or the need for tracheal re-intubation or tracheotomy. We discuss the importance of informed consent for the patient and family.

Hyperoxemia in mechanically ventilated, critically ill subjects: incidence and related factors

BACKGROUND

Excessive supplemental oxygen causes injurious hyperoxemia. Before establishing the best P(aO2) targets for mechanically ventilated patients, it is important to understand the incidence of hyperoxemia and related factors. We investigated oxygenation in mechanically ventilated subjects in our ICU and evaluated factors related to hyperoxemia (P(aO2) > 120 mm Hg) at 48 h after initiation of mechanical ventilation.

METHODS

We retrospectively reviewed the medical records of patients admitted to our ICU from January 2010 to May 2013. Inclusion criteria were 15 y of age or older and administration of mechanical ventilation for > 48 h. Patients at risk of imminent death on admission or who had received noninvasive ventilation were excluded. We collected subject demographics, reasons for mechanical ventilation, and during mechanical ventilation, we collected arterial blood gas data and ventilator settings on the first day of intubation (T1), 48 h after initiation of mechanical ventilation (T2), and on the day of extubation (T3). Multivariable logistic regression analysis was performed to clarify independent variables related to hyperoxemia at T2.

RESULTS

For the study period, data for 328 subjects were analyzed. P(aO2) statistically significantly increased over time to 90 (interquartile range of 74-109) mm Hg at T1, 105 (89-120) mm Hg at T2, and 103 (91-119) mm Hg at T3 (P < .001), coincident with decreases in F(IO2) of 0.4 (0.3-0.5) at T1, 0.3 (0.3-0.4) at T2, and 0.3 (0.3-0.35) at T3 (P < .001). Hyperoxemia occurred in 15.6% (T1), 25.3% (T2), and 22.4% (T3) of subjects. Multivariable logistic regression analysis revealed that hyperoxemia was independently associated with age of < 40 y (odds ratio 2.6, 95% CI 1.1-6.0), Acute Physiology and Chronic Health Evaluation II scores of ≥ 30 (odds ratio 0.53, 95% CI 0.3-1.0), and decompensated heart failure (odds ratio 1.9, 95% CI 1.1 to 3.5).

CONCLUSIONS

During mechanical ventilation of critically ill subjects, P(aO2) increased, and F(IO2) decreased. One in 4 subjects were hyperoxemic at T2, and hyperoxemia persisted until T3.

[Delayed discharge from the intensive care unit]

BACKGROUND

Delayed discharge from ICU to the general ward can exert an adverse effect. We researched whether patients are discharged smoothly from our ICU to the general ward.

METHODS

We defined that patients were eligible for discharge if they are without administration of catecholamine, being assisted by mechanical ventilation and having blood purification therapy.

RESULTS

Average time from actual discharge to the time patient was considered eligible for discharge was fifteen hours. This study was retrospective.

CONCLUSIONS

We need to investigate further the reasons why delayed discharge occurred. It is im portant that patients are discharged from the ICU to the general ward properly. Delayed discharge can delay the recovery and expose the patient to multi-resistant microorganisms. We studied whether patients are discharged smoothly from the ICU to the general ward.

Complete bronchial obstruction by granuloma in a paediatric patient with translaryngeal endotracheal tube: a case report

Introduction

Although continuous or frequent stimuli in tracheostomized patients may cause tracheal granulomas, little is known about management of patients with translaryngeal intubation.

Case presentation

A 1-month-old Japanese boy, weighing 3.5kg, was admitted to our hospital owing to cardiac failure caused by an atrial septal defect and intractable arrhythmia. To treat his unstable cardiovascular status, surgery was performed to close his atrial septal defect. After the operation, stenosis was detected by auscultation and flow limitation worsened. A bronchoscopy revealed granulomas completely obstructing his right bronchus and partially obstructing his left bronchus. Dexamethasone infusion partially reduced the mass, after which removal by yttrium aluminium garnet laser was tried. The airway obstruction was not resolved, however, because of granuloma reproliferation. Budesonide (aerosol liquid) inhalation was started, and tissue was reduced using an yttrium aluminium garnet laser and physically removed using forceps. After continued budesonide inhalation, he was successfully liberated from the ventilator.

Conclusions

Life-threatening airway obstruction by granulomas developed in a translaryngeally intubated paediatric patient. The granuloma was detected after a couple of weeks of intubation. A bronchial granuloma is rare in paediatric patients. It should be suspected with evidence of bronchial obstruction. Treatment with corticosteroids and surgery using a laser maybe indicated.

Successful use of extracorporeal membrane oxygenation in the reversal of cardiorespiratory failure induced by atonic uterine bleeding: a case report

Introduction

Although extracorporeal membrane oxygenation has made sufficient progress to be considered for the management of life-threatening cardiac and respiratory failure, the risk of hemorrhagic complications may outweigh the benefits for patients with bleeding tendencies. We report, to the best of our knowledge, the first case of successful treatment by extracorporeal membrane oxygenation, without any hemorrhagic complications, of postpartum cardiorespiratory failure after massive uterine bleeding.

Case presentation

A 25-year-old Japanese woman experienced massive atonic bleeding after delivering her second baby. Recovery from hemorrhagic shock was managed by conservative treatments, but she developed decompensated heart failure and refractory hypoxia. Because we could not obtain hemodynamic stability and proper oxygenation even with high doses of catecholamines and maximal ventilator settings, we administered venoarterial extracorporeal membrane oxygenation, whereupon her hemodynamic status immediately stabilized. After 72 hours of support without major bleeding, extracorporeal membrane oxygenation was successfully withdrawn.

Conclusion

Even in cases of obstetric bleeding, if clotting status is stringently monitored, extracorporeal membrane oxygenation can be considered as an ultimate means of life support.

A novel method of post-pyloric feeding tube placement at bedside

PURPOSE

Post-pyloric feeding tube placement is often difficult, and special equipment or peristalsis agents are used to aid insertion. Although several reports have described blind techniques for post-pyloric feeding-tube placement, no general consensus about method preference has been achieved.

MATERIALS AND METHODS

The technique is performed as follows: via the nostril, a stylet-tipped feeding tube is advanced about 70 cm; to confirm tip location to the right of the epigastric area, towards the right hypochondriac region, 5 mL shots of air are injected to enable touch detection of bubbling; finally, the tube is advanced to a length of 100 cm, during which the strength of bubbling seems to diminish under palpation.

RESULTS

We prospectively enrolled consecutive patients whose oral intake was expected to be difficult for 48 hours in the intensive care unit. Forty-one patients were enrolled and the rate of successful placement at first attempt was 95.1%. Mean duration for successful placement was 15 minutes.

CONCLUSIONS

With a novel technique, from the bedside, without special tools or drugs, we successfully placed post-pyloric feeding tubes. Essential points when inserting the tube are confirmation of the location of the tube tip by palpation of injected air, and to avoid deflection and looping.

Effect of high-flow nasal cannula on thoraco-abdominal synchrony in adult critically ill patients

BACKGROUND

High-flow nasal cannula (HFNC) creates positive oropharyngeal airway pressure and improves oxygenation. It remains unclear, however, whether HFNC improves thoraco-abdominal synchrony in patients with mild to moderate respiratory failure. Using respiratory inductive plethysmography, we investigated the effects of HFNC on thoraco-abdominal synchrony.

METHODS

We studied 40 adult subjects requiring oxygen therapy in the ICU. Low-flow oxygen (up to 8 L/min) was administered via oronasal mask for 30 min, followed by HFNC at 30-50 L/min. Respiratory inductive plethysmography transducer bands were circumferentially placed: one around the rib cage, and one around the abdomen. We measured the movement of the rib-cage and abdomen, and used the sum signal to represent tidal volume (V(T)) during mask breathing, and at 30 min during HFNC. We calculated the ratio of maximum compartmental amplitude (MCA) to V(T), and the phase angle. We assessed arterial blood gas and vital signs at each period, and mouth status during HFNC. We used multiple regression analysis to identify factors associated with improvement in thoraco-abdominal synchrony.

RESULTS

During HFNC, breathing frequency significantly decreased from 25 breaths/min (IQR 22-27 breaths/min) to 21 breaths/min (IQR 18-24 breaths/min) (P < .001), and MCA/VT (P < .001) and phase angle (P = .047) significantly improved.

CONCLUSIONS

HFNC improved thoraco-abdominal synchrony in adult subjects with mild to moderate respiratory failure.

Molecular identification of Fasciola spp. (Digenea: Platyhelminthes) in cattle from Vietnam

Fasciola spp. were collected from naturally infected cattle at a local abattoir of Khanh Hoa province, Vietnam, for morphological and genetic investigations. Microscopic examination detected no sperm cells in the seminal vesicles, suggesting a parthenogenetic reproduction of the flukes. Analyses of sequences from the first and second internal transcribed spacers (ITS1 and ITS2) of the ribosomal RNA revealed that 13 out of 16 isolates were of Fasciola gigantica type, whereas three isolates presented a hybrid sequence from F. gigantica and Fasciola hepatica. Interestingly, all the mitochondrial sequences (partial COI and NDI) were of F. gigantica type, suggesting that the maternal lineage of the hybrid form is from F. gigantica. No intra-sequence variation was detected.

Prevalence of intestinal parasites and genotyping of Giardia intestinalis in pet shop puppies in east Japan

The current study examined the prevalence of intestinal parasites and genotypes of Giardia intestinalis in puppies from nine pet shops in east Japan. Fresh fecal samples from 1794 puppies (≦3 months old) were collected on one occasion. Giardia spp. was examined for specific coproantigen using ELISA kit (SNAP®Giardia, IDEXX Laboratories, Inc., USA). Other intestinal parasites were detected microscopically using the formalin-ethyl acetate sedimentation technique. Genotyping was determined for the random 29 stool samples identified as Giardia spp. positive using PCR and direct sequencing of the glutamate dehydrogenase (gdh) gene. Overall prevalence of protozoan Giardia spp. and Cystoisospora spp. revealed 23.4% and 11.3%, respectively. Prevalence of ascarids, Strongyloides spp. and hookworms were recorded 1.8%, 1.1% and 0.1%, respectively. Protozoan Giardia spp. and Cystoisospora spp., thus, represent important pathogens among pet shop puppies. All genotyped G. intestinalis isolates were belonged to assemblage C or D, identified as dog-specific genotypes. Zoonotic assemblage A and B were not demonstrated. The result suggests that the risk of zoonotic transmission of G. intestinalis from pet shops puppies to humans may be quite low in Japan.

[Inadvertent thoracic duct puncture during right axially central venous cannulation]

A case of inadvertent thoracic duct puncture during right axially central venous cannulation is reported. The catheterization was performed under the real time ultrasound guidance technique and the coronal view image was continuously displayed. After confirming the feelings of venous puncture, clear yellow fluid was aspired into the connected syringe to the needle. Initially, an accidental thoracic puncture with subsequent pleural fluid aspiration was suspected;however, no finding of pleural effusion was observed with ultrasound imaging and computed tomography. Thus, an accidental thoracic duct puncture and the subsequent lymph fluid aspiration were suspected. Even in a right side approach for central venous catheterization, thoracic duct injury might ensure.

[Successful extubation in a patient with alacepril-induced tongue angioedema]

We describe a case of marked swelling of the tongue in a patient after a long prone position neurosurgery, who was treated for hypertension with alacepril. The tongue was not congestive and history of taking an angiotensin-converting enzyme inhibitor suggested an alacepril-induced angioedema. The day after surgery, the patient's tongue was still swollen; however, fibrescopic observation of the larynx and pharynx through the nasal cavity revealed that the edema was limited to anterior tongue, and the oral cavity and oropharynx were not involved. Although, tongue angioedema was observed, we introduced a 3-mm tube exchanger to the patient's trachea and removed the endotracheal tube. The ventilation and oxygenation were maintained, and 30 min later, the exchanger was detached. On the second postoperative day, the angioedema disappeared completely and the patient was transferred to a ward without any complication.

[Nasogastric tube syndrome suspected at the end of anesthesia]

The case of a patient who might have developed nasogastric tube syndrome at the end of anesthesia is presented. A 62-year-old woman was scheduled for a general anesthesia with fiberscopic oro-tracheal intubation because of a predicted difficult airway. After the smooth and gentle intubation without any trauma and injury, a nasogastric tube was inserted blindly. At the end of surgery, the anesthesiologists observed the pharyngeal tissue and found significant edema on the epiglottis and arytenoids. Extubation was cancelled and the patient was moved to an intensive care unit for respiratory management. On the next day, fiberscopic observation revealed a complete recovery and the endotracheal tube was removed without any difficulty. We strongly suspected the pharyngeal injury as acute nasogastric tube syndrome and an attention to this rare complication is required by anesthesiologists.

[Apnea and severe respiratory depression induced by dexmedetomidine after general anesthesia in intensive care unit]

Dexmedetomidine (DEX) is widely used in intensive care unit for perioperative sedation. The one advantage of DEX administration for sedation is the lack of significant respiratory depression. However, DEX shows significant interaction with anesthetics and narcotics, and we present a case in which post-anesthetic administration of DEX induced apnea and severe respiratory depression after extubation. A 74-year-old, 38.3 kg, 148 cm woman was scheduled to undergo implantation of internal cardiac defibrillator. General anesthesia was maintained by sevoflurane, remifentanil and intermittent administration of fentanyl. After the surgery, she was transferred to intensive care unit with intubation, and DEX administration was commenced. After 3.5 hr from the end of anesthesia, the patient's trachea was extubated under continuous infusion of DEX (0.26 microg x kg(-1) x hr(-1)). Ninety min later, she showed apnea and severe respiratory depression. The interaction of DEX and residual narcotics might have induced life-threatening respiratory complication.

[Serotonin syndrome caused by an overdose of dextromethorphan, Medicon]

We report the first case of serotonin syndrome caused by overdose of dextromethorphan in Japan. A 34-year-old woman with schizophrenia received a dextromethorphan (Medicon) for a catarrhal symptom from two individual departments of the university hospital by chance. The daily amount of dextromethorphan was up to 180 mg for several days in addition to other regular antipsychotic drugs including risperidone, amitriptyline and levomepromazine. Finally, she was found in deep comatose state (GCS coma scale: E1V1M1) and the trachea was intubated in the emergency room. After admission to intensive care unit, the consciousness gradually improved; however, she was confused and agitated. The situation was normalized within next 24 hours and she was weaned from the mechanical ventilation next day. Serotonin syndrome demonstrates various signs and might be overlooked in an emergency room. Dextromethorphan is considered as a safe antitussive drug; however, the unexpected interaction should be suspected during chronic medical treatment.

Nafamostat prevents hypothermia and improves survival time after administration of lipopolysaccharide in a mouse surgical model

Lipopolysaccharide (LPS) is an endotoxin known to induce disseminated intravascular coagulation and multiple organ failure followed by septic shock in animals. Nafamostat is a synthetic protease inhibitor with anticoagulant effects. This study investigated the effect of systemic administration of nafamostat on thermogenic homeostasis and survival time in a mouse surgical model. Male C57Bl/6 mice were anesthetized with sevoflurane and implanted with intraabdominal telemetry transmitters. Following the surgery, three groups of animals were administered Escherichia coli LPS (0127: B8) subcutaneously at doses of 0.3, 1.0, or 3.0 mg kg(-1), and one group received saline without LPS. Three other groups received 3 mg.kg(-1) LPS with 1, 3, or 10 mg kg(-1) of nafamostat. In another group 10 mg kg(-1)1 of nafamostat only was administered. The times to the onset of hypothermia (body temperature < 30 degrees C) and death were determined. L LPS significantly shortened the duration of both normothermia and survival, and nafamostat prolonged the normothermic periods that were reduced b 3 mg.kg(-1) LPS. Survival time was significantly correlated with the duration of normothermia (n = 48; r (2) = 0.779; P < 0.000001). The results demonstrated the effect of systemic administration of nafamostat against LPS-induced hypothermia. Nafamostat prevented hypothermia, and the consequent normal thermoregulation may have prolonged the survival period.

[Multiple difficulties for central venous access required the distal femoral vein catheterization: a case report]

The low femoral approach for catheterization of the central venous line is a difficult procedure because the surface landmark technique is not helpful. We report a case of patient who required the distal femoral cannulation. Re-catheter cannulation was planned for the patient after the major cardiovascular surgery. The right internal jugular vein showed the venous thrombus attributed to the previous catheter placement for the operation. The left internal, jugular vein had anatomical anomaly at the level of cricoid cartilage and the last approach for cannulation was not feasible. The right subclavian and right femoral regions were scarred with the surgical procedure. Finally, we performed the distal femoral cannulation using real time ultrasound guidance. When multiple difficulties for venous access are present, ultrasound-guided low approach of femoral vein might be one of the solutions.

[Two cases of anesthesia mumps in the upper parotid gland after general anesthesia in the lateral position]

We describe two cases of acute transient swelling of the upper side of parotid glands of the patients after general anesthesia in the lateral position. The serum amylase levels in the patients were not increased and the enlargement of the parotid gland was diagnosed as anesthesia mumps. Previous reports suggested that mechanical compression might produce the swelling of the secreting organ, but our patients showed temporal parotid enlargement in the upper free side. Although, pre-medication with atropine might become a cause of parotid gland swelling, we anesthetized these patients without anti-cholinergic drugs. Procedures of oro-tracheal intubation and stimuli of endotracheal tube may induce impairment of the normal flow of saliva and lead to enlargement of the parotid gland.