Retrospective evaluation of the respiratory rate-oxygenation index to predict the outcome of high-flow nasal cannula oxygen therapy in dogs (2018-2021): 81 cases.

OBJECTIVE: To evaluate the respiratory rate-oxygenation index (ROX), modified ROX index (ROX-HR), and the ratio of pulse oximetry saturation (Spo2) to Fio2 (SF) to determine if these indices over time are predictive of outcome in dogs treated with high-flow nasal cannula oxygen therapy (HFNC). DESIGN: Retrospective study. SETTING: Two university teaching hospitals. ANIMALS: Eighty-one client-owned dogs treated with HFNC for hypoxemic respiratory failure. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The ROX was defined as the SF divided by the respiratory rate (RR), and the ROX-HR was defined as the ROX divided by the heart rate multiplied by 100. The overall success rate of HFNC was 44% (n = 36/81). Dogs weaned from HFNC had a significantly higher ROX (P < 0.0001) at 1-3, 5-10, 12, and 15 hours than dogs that failed HFNC. Both the ROX and SF showed excellent discriminatory power in predicting HFNC failure at 6 hours, with an area under receiver operating curve of 0.85 (95% confidence interval: 0.72-0.99; P < 0.002) and 0.86 (95% confidence interval: 0.73-0.99; P < 0.001), respectively. The optimal cutoff values for predicting HFNC failure at 6 hours were a ROX ≤3.68 (sensitivity 72%, specificity 92%) and an SF ≤143 (sensitivity 79%, specificity 93%). CONCLUSIONS: These results suggest that similar to people, the ROX and SF are useful predictors of HFNC failure. These indices are easy to measure at the bedside and may have clinical use. Future prospective studies are warranted to confirm the findings and to optimize cutoff values in a larger population of dogs undergoing HFNC.

High-flow nasal cannula improves hypoxemia in dogs failing conventional oxygen therapy.

OBJECTIVE: A prospective clinical trial was performed to evaluate the efficacy and tolerance of high-flow nasal cannula (HFNC) in dogs with hypoxemia. ANIMALS: 20 client-owned dogs failing conventional oxygen therapy (COT). PROCEDURES: Patients admitted to the ICU for treatment of hypoxemic respiratory failure were enrolled in the study. PaO2, SPO2, respiratory rate (RR), and acute patient physiologic and laboratory evaluation scores were obtained at the time of COT failure and after initiation of HFNC. Complications and patient tolerance while receiving HFNC were also recorded. RESULTS: Compared to COT, the median PaO2 and SO2 were significantly higher when dogs were receiving HFNC (60.8 vs 135.6 mm Hg and 90.7% vs 99.25%, respectively). Dogs receiving HFNC had a significant reduction in median RR as compared to dogs undergoing COT (52 vs 36 breaths per minute). After the initiation of HFNC, all dogs showed clinical improvement as measured by PaO2, SO2, and RR. Of 20 dogs, 6 ultimately failed HFNC and mechanical ventilation was recommended. Nine dogs undergoing HFNC survived to discharge, and acute patient physiologic and laboratory evaluation scores had a significant positive severity correlation with death. Complications included pneumothorax in 1 dog. CLINICAL RELEVANCE: COT has limited flow rates due to airway irritation caused by room temperature, nonhumidified oxygen. HFNC uses vapor humidification and heated oxygen, allowing for higher flow rates. In people, HFNC is used as escalation of oxygen therapy when COT fails. Dogs treated with HFNC had significant improvements in PaO2, SO2, and RR as compared to COT. HFNC is well tolerated and effective in treating hypoxemia in dogs.

A Review of High Flow Nasal Cannula Oxygen Therapy in Human and Veterinary Medicine.

Respiratory distress is a common ailment in small animal medicine. Oxygen supplementation is a mainstay of initial therapy. High Flow Nasal Cannula Oxygen Therapy (HFNCOT) has become increasingly popular as a treatment modality in human medicine, and more recently in canine patients. These devices deliver high flow rates of heated and humidified oxygen at an adjustable fraction of inspired oxygen . This article reviews current literature in human patients on HFNCOT as well as studies that have evaluated its use in veterinary patients. A discussion of the respiratory physiology that is associated with respiratory distress, in addition to an overview of currently available oxygen supplementation modalities is provided. The physiologic benefits of HFNCOT are explained, as are technical aspects associated with its use. Recommendations on initial settings, maintenance therapy, and weaning are also described.

Preliminary evaluation of the use of high-flow nasal cannula oxygen therapy during recovery from general anesthesia in dogs with obstructive upper airway breathing.

BACKGROUND: Brachycephalic airway syndrome can pose a risk of complicated recovery from anesthesia as a result of irritation to the excess pharyngeal andlaryngeal tissue present in affected dogs. High-flow nasal cannula (HFNC) oxygen therapy is a respiratory support modality that offers provision of continuous positive airway pressure via high gas flow rates. The HFNC system actively warms and humidifies inspired gases, which improves comfort and facilitates tolerance of the high flow rates in people and dogs. HFNC oxygen therapy was applied to brachycephalic dogs that developed increased work of breathing or hypoxemia in the recovery phase of anesthesia to determine if this device would be tolerable and effective for relief of upper respiratory difficulty. KEY FINDINGS: The HFNC nasal prong interface is well suited to the brachycephalic facial structure. The application of HFNC was found to reduce dyspnea scores in patients with signs of upper airway obstruction after general anesthesia. Aerophagia and changes in PCO2 were noted. SIGNIFICANCE: Application of HFNC in the recovery period may result in improved airflow during times of somnolent obstructive breathing, not unlike the use of continuous positive airway pressure therapy in sleep-disordered breathing in people.

Improved simple T-cannula technique to facilitate surgery and daily skin care of growing pigs.

In order to further increase the stability of the cannula behind the ribs and to facilitate cannula exteriorization in growing pigs, the present study aimed to evaluate whether elongation of the cannula flange could increase the stability of the cannula behind the ribs and to develop a tool to improve the exteriorization of the cannula through the ribs. Moreover, it was assessed whether a special skin protection paste and soft polyurethane foam material used in daily skin care could prevent erythema around the fistula. The feasibility of both, the modified simple T-cannula and daily skin care procedure, was evaluated in a digestibility experiment. Simple T-cannulae were made of high-molecular-weight polyethylene and inserted into the distal ileum of eight growing pigs (average body weight at surgery 30 kg). Modifications in the cannula design included a longer flange (11 cm) that was narrowed from the center to the ends and a bending of the flange to adapt it to the curve of the costal arch. In order to reduce the damage to the thread on the outer cannula barrel during surgery, a special surgical plug in conjunction with a screw thread on the inside of the barrel was developed. With respect to the daily cleaning of the fistula, a special skin protection paste was applied on the skin around the fistula to create a waterproof film that entirely sealed the skin. Additionally, foam material was inserted between the retaining ring and the skin to absorb the leaking digesta. Monitoring of the pigs throughout the trial showed that modifications in cannula design proved to be useful as they facilitated exteriorization of the cannula through the ribs and stability of the cannula behind the ribs. Moreover, the use of the skin protection paste and foam material during postsurgical treatment of growing pigs effectively prevented skin irritation around the flank area.

Comparison of high flow nasal cannula oxygen administration to traditional nasal cannula oxygen therapy in healthy dogs.

OBJECTIVE: To determine the feasibility, degree of respiratory support, and safety of high flow nasal cannula (HFNC) oxygen therapy in sedated and awake healthy dogs, when compared to traditional nasal cannula (TNC) oxygen administration. DESIGN: Randomized experimental crossover study. SETTING: University research facility. ANIMALS: Eight healthy dogs. INTERVENTIONS: Variable flow rates (L/kg/min) were assessed, TNC: 0.1, 0.2, and 0.4 and HFNC: 0.4, 1.0, 2.0, and 2.5. HFNC was assessed in sedated and awake dogs. MEASUREMENTS: Variables measured included: inspiratory/expiratory airway pressures, fraction of inspired oxygen (FiO2 ), end-tidal oxygen (ETO2 ), end-tidal carbon dioxide (ETCO2 ), partial pressure of oxygen (PaO2 ), partial pressure of carbon dioxide (PaCO2 ), temperature, heart/respiratory rate, arterial blood pressure, and pulse oximetry. Sedation status, complications, and predefined tolerance and respiratory scores were recorded. MAIN RESULTS: Using HFNC, continuous positive airway pressure (CPAP) was achieved at 1 and 2 L/kg/min. CPAP was not higher at 2.5 than 2 L/kg/min, with worse tolerance scores. Expiratory airway pressures were increased when sedated (P = 0.006). FiO2 at 0.4 L/kg/min for both methods was 72%. FiO2 with TNC 0.1 L/kg/min was 27% and not different from room air. The FiO2 at all HFNC flow rates ≥1 L/kg/min was 95%. PaO2 for HFNC 0.4 L/kg/min was lower than at other flow rates (P = 0.005). The only noted complication was aerophagia. PaCO2 was increased with sedation and use of HFNC when compared to baseline (P = 0.006; P < 0.01). CONCLUSIONS: Use of HFNC in dogs is feasible and safe, provides predictable oxygen support and provides CPAP, but may cause a mild increase in PaCO2 . Flow rates of 1-2 L/kg/min are recommended. If using TNC, flow rates above 0.1 L/kg/min may attain higher FiO2 .

Duodenal infusions of isoleucine influence pancreatic exocrine function in dairy heifers.

Four healthy Holstein heifers (235 ± 12 kg) fitted with duodenal and pancreatic cannulas were used to investigate infusion of isoleucine (Ile) on the pancreatic exocrine function in a 4 × 4 Latin square design. Three doses of Ile, 10, 20 and 30 g in 2500 ml water, respectively, were infused into the duodenum over a period of 12 h in Experiment (Exp) 1 and over 10 d in Exp 2. Hourly pancreatic juice and jugular blood were taken during the infusion period in Exp 1, and the blood samples were taken in 2-h intervals over the last 2 d in Exp 2. Compared with no Ile infusion, the Ile infusions in both experiments increased the concentration and secretion rate of the protein, activity of ɑ-amylase and trypsin and plasma cholecystokinin. The secretion rate of ɑ-amylase and the activity of trypsin linearly increased with the Ile doses. The pancreatic juice secretion linearly increased with Ile in Exp 2 but not in Exp 1. Isoleucine linearly increased plasma insulin in Exp 1, but not in Exp 2. No effects of Ile on pH of pancreatic juice, the activity of chymotrypsin and lipase and plasma glucose were found. In conclusion, duodenal Ile infusion could increase the pancreatic exocrine function of Holstein heifers, especially ɑ-amylase, and the increment appeared to be dose and time dependent.

Evaluation of oxygen administration with a high-flow nasal cannula to clinically normal dogs.

OBJECTIVE To evaluate the safety and efficacy of oxygen administration by use of a high-flow nasal cannula (HFNC) in sedated clinically normal dogs. ANIMALS 6 healthy adult dogs undergoing routine dental prophylaxis. PROCEDURES Dogs were sedated with butorphanol tartrate and dexmedetomidine. An esophageal balloon catheter was inserted into the esophagus, a double-pronged nasal cannula was inserted into the nares, and a catheter was inserted into the dorsal pedal artery. Dogs were positioned in right lateral recumbency. After a 6-minute acclimation period, baseline blood gas values and transpulmonary pressure were measured. Dogs then received supplemental oxygen via conventional oxygen therapy (COT) at a rate of 100 mL/kg/min (COT-100 treatment) and an HFNC at a rate of 20 L/min (HF-20 treatment) and 30 L/min (HF-30 treatment). Arterial blood gas and transpulmonary pressure were measured after a 6-minute acclimation period for each oxygen delivery method. Radiographs were obtained before and after oxygen administration to evaluate gastric distension. RESULTS Median Pao2 was significantly higher for HF-20 (519.9 mm Hg) and HF-30 (538.1 mm Hg) treatments, compared with median Pao2 for the COT-100 treatment (202.9 mm Hg). The Pao2 did not differ significantly between the HF-20 and HF-30 treatments. There was no significant difference in Paco2 or change in transpulmonary pressure between baseline and any oxygen delivery method. CONCLUSIONS AND CLINICAL RELEVANCE In this study, HFNC appeared to be a safe and effective method for oxygen delivery to sedated healthy dogs. Further studies are needed to evaluate use of HFNCs for oxygen administration to hypoxemic patients.

Retrospective evaluation of the effect of high flow oxygen therapy delivered by nasal cannula on PaO2 in dogs with moderate-to-severe hypoxemia.

OBJECTIVE: To describe the effects of high flow oxygen therapy (HFOT) in canine patients failing traditional oxygen therapy (TOT). DESIGN: Retrospective study. SETTING: Private referral practice. ANIMALS: Six client-owned dogs with primary pulmonary hypoxemia. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: High flow oxygen was delivered by high flow nasal prongs to dogs assessed clinically to be failing TOTs. HFOT was able to significantly improve PaO2 compared to TOT in severely hypoxemic dogs (median, 133.75 mm Hg; range, 109.2-304.8) versus median 61.85 mm Hg (range, 52.3-71.8; xsP = 0.0412). Flow rates were significantly higher with HFOT compared to TOT (median, 688 mL/kg/min; range, 523-1,667 mL/kg/min) versus median 122 mL/kg/min (range, 80-208; P = 0.0412). Complications included patient discomfort requiring light sedation in 1/6 dogs and persistence of a pneumothorax in 1 dog. Hypoxemia resolved in 4/6 dogs. CONCLUSION: These data suggest HFOT is a viable clinical intervention for dogs with moderate-to-severe hypoxemia assessed to be failing TOT. Further studies are needed to determine if HFOT can be used as an alternative to mechanical ventilation in resource limited settings and to characterize the complications associated with this therapy.

A retrospective evaluation of polyurethane, long-stay, peripheral venous cannulae in dogs undergoing radiotherapy.

OBJECTIVES: The aim of this retrospective study was to review placement duration and associated complications of long-stay, peripheral venous cannulae in dogs undergoing a radiotherapy protocol. Factors affecting duration of stay of the cannulae were evaluated. METHODS: The records of patients which had a single-lumen, 16-gauge, 16-cm polyurethane cannulae inserted into a peripheral vein between 2010 and 2014 were reviewed. RESULTS: Forty-one cannulae were placed in 41 patients. Median duration of cannula stay was 14 days (range 2 to 26). In 14 cases (~34%) the cannula was removed at the end of the radiotherapy course. In 13 (~32%) cases, cannula-related complications resulted in premature removal. Use of steroids and antibiotics appeared to be associated with a longer median duration of stay. CLINICAL SIGNIFICANCE: No life-threatening complications were encountered. Indwelling, polyurethane, saphenous cannulae were an effective and safe way to maintain venous access in this group of patients. Prednisolone and antibiotics were typically commenced for acute radiation side effects -midway through the protocol; therefore their association with length of stay may not be a direct result of their administration.