Does do not resuscitate (DNR) always mean DNR? Exploring DNR orders in small animal veterinary medicine

Abstract

This study investigated the use of and adherence to do not resuscitate (DNR) orders in small animal veterinary medicine. A link to a survey of respondent characteristics and clinical scenarios in which interpretation of the DNR order was questionable was distributed by e-mail to veterinarians in specialty and general practice, veterinary technicians, and veterinary students on veterinary e-mail lists in North America and Europe. Complete responses were obtained from 648 individuals, including 493 veterinarians, 58 veterinary technicians, and 97 veterinary students. Men, experienced veterinarians, and respondents participating in multiple cardiopulmonary resuscitation (CPR) events yearly were more likely to perform CPR despite DNR orders. Veterinarians in North America were more likely to provide CPR, compared to those elsewhere. Most respondents would override a DNR in the case of an in-hospital iatrogenic cardiac arrest or unexpected arrest during sedation, but would provide CPR when requested by owners, even if judged futile. Codes are not routinely suspended for patients undergoing anesthesia or regularly re-evaluated during hospitalization.

Key clinical message: Inconsistency surrounding the assignment of and adherence to DNR orders in veterinary patients should be considered when establishing protocols for discussion and implementation of CPR codes.

Introduction

Cardiopulmonary arrest (CPA) is commonly described in hospitalized, critically ill dogs and cats, those presenting to the ER, or those undergoing anesthesia. Because of the risk of CPA, hospitals may solicit a resuscitation code from pet owners, which indicates whether they elect for CPR to be conducted, and at what level. The code classification system used most often in veterinary practice consists of 3 codes, green for open chest cardiopulmonary resuscitation (CPR), yellow for closed chest CPR, or red, indicating do not resuscitate (DNR). Studies of success of CPR in veterinary patients report rates of survival to discharge of 3% to 22% (1–4). More recently, the RECOVER initiative published evidence and consensus based treatment recommendations for small animal CPR (5).

Few studies, however, have specifically addressed issues surrounding patient code assignments, in particular, DNR status. One study surveyed academic veterinarians on their approaches to CPR and found that quality of life had the most significant impact on veterinarians’ decisions to resuscitate a patient. In addition, they found that most veterinarians felt they should make recommendations to clients when discussing DNR, but that the final decision should be made by the owner (6). Additionally, survey results reported stress among veterinarians associated with discussing CPR and DNR choices with clients (7).

Despite widespread use of the term, uncertainty remains regarding whether an established DNR order should always be followed. This is particularly relevant in circumstances such as perianesthetic and iatrogenic CPA, in which CPR success is higher (8,9). Knowledge of higher success rates may cause clinicians to deviate from an existing DNR order. The topic of overriding a DNR code in the case of an iatrogenic, reversible CPA has been explored in human medicine, but has yet to be examined in the veterinary field (10).

In accordance with the most recent guidelines published by the American Society for Anesthesiologists, many human hospitals practice “required reconsideration,” in which DNR orders are re-evaluated before surgical procedures, to discuss the option of temporarily suspending these orders in the perioperative period (11). It is possible that protocols such as these exist in veterinary hospitals, or are completed on a patient-by-patient basis. Veterinary literature on the subject, however, is lacking.

The purpose of this study was to investigate the adherence of veterinarians, veterinary technicians, and veterinary students to established DNR orders in various clinical scenarios. Our hypothesis was that because DNR status is not always straightforward, there may be differences among these groups in how they respond to CPA.

Materials and methods

An internet questionnaire was developed to survey veterinarians, veterinary technicians, and veterinary students on the use of CPR codes and the clinical application of DNR orders. Survey participation was voluntary, and responses were anonymous. The survey was approved by the Institutional Review Board of Tufts University. The link to the survey was distributed by e-mail using mail listserv groups. These groups included veterinary students and technicians at the Cummings School of Veterinary Medicine at Tufts University, members of the Veterinary Emergency and Critical Care Society, and Diplomates of the American College of Veterinary Emergency & Critical Care, the American College of Veterinary Surgeons, the American College of Veterinary Anesthesia and Analgesia, and the American College of Veterinary Internal Medicine. The link was also distributed to the European Veterinary Emergency and Critical Care Society, the European College of Veterinary Emergency & Critical Care, the European College of Veterinary Anesthesia and Analgesia, the European College of Veterinary Surgeons, the European Society of Veterinary Internal Medicine, the European Society of Veterinary Cardiology, and the European Society of Veterinary Neurology. The total of listserv e-mail addresses was approximately 1800, but 1 technician group was a social media based listserv for which numbers were not available. Requests to participate in the survey were sent August 4, 2014 with a reminder August 21, 2014, and data were collected 2 wk following the reminder. On average, the survey was completed in 7 min.

The survey included questions about participants’ demographics, experience with CPR, use of CPR codes, and interpretation of clinical scenarios involving DNR orders and CPA. Most questions were multiple choice style with 1 response allowed per question. Three questions allowed the option to write in an answer, including participant’s country, specialty, and an open-ended prompt requesting further comments on CPR and codes. Initial questions asked for respondent’s gender and occupation. The question regarding occupation subdivided respondents into categories, allowing specific follow-up questions to be asked of students, veterinary technicians, and veterinarians, independently (e.g., student year, length of time in practice, specialty, geographic location). All respondents were then asked about their experience with CPR, including whether they received formal education in CPR and number of CPR events participated in per year. Those who responded that CPR codes were assigned at their hospital were asked specific questions about assignment of those codes.

The last portion of the survey asked participants how they would respond to 5 clinical scenarios involving CPA (Appendix I). In the first 4, the patient in question has a DNR code in place at the time of the arrest. The scenarios chosen were intended to reflect those one might encounter in a veterinary hospital setting. Multiple choice options included various levels of intervention to account for the diverse responses that might be expected of clinicians encountering CPA.

Appendix I.

Scenarios given to survey respondents.

Scenario	Response choices
You have a dog under anesthesia for surgery for a solitary lung tumor. The dog has a DNR order which was entered by the ER vet the night before. You question the DNR order, and the ER team reports that this doctor always talks owners out of CPR. This is a routine surgery, so you continue as planned but make a note to address this with the ER the next day. During induction cardiac arrest occurs. Do you:	Provide full CPR (chest compressions, ventilation, medications) Provide limited support — provide ventilation but no chest compressions Provide no CPR
You have a dog under anesthesia for surgery for a solitary lung tumor. The dog has a DNR order which was entered by the ER vet the night before. You question the DNR order, and the ER team reports that this doctor always talks owners out of CPR. This is a routine surgery, so you continue as planned but make a note to address this with the ER the next day. During induction cardiac arrest occurs. Do you:	Provide full CPR (chest compressions, ventilation, naloxone) Provide naloxone and intubation but no chest compressions Administer naloxone only Provide no CPR
A dog with severe bite wounds is admitted to the ER. Due to the severity of the injuries, the owner elects a DNR at the time of admission. The dog recovers well from the wounds and is almost ready for discharge 5 days later. The dog unexpectedly experiences cardiac arrest during sedation with dexmedetomidine for a bandage change. Do you:	Provide full CPR (chest compressions, ventilation, reversal agents) Provide limited support — reversal agents and intubation but no chest compressions Administer reversal agents only Provide no CPR
A long-standing cardiology patient “Bella” with moderately severe DCM presents to the ER. The cardiologist has previously discussed with the owners the progression of congestive heart failure, and the owners decided in advance that they would not want Bella intubated in the instance of severe dyspnea, and so entered a DNR order in her medical record. She is presented by the pet sitter, who has accidentally administered a massive overdose of digoxin. She experiences CPA shortly after arriving in the hospital. Would you perform CPR on this patient?	Yes No
A patient with severe metastatic disease from hemangiosarcoma has been hospitalized in your ICU for the past 3 days. The dog has progressive azotemia and has become unresponsive to chemotherapy. The owners do not want to give up on their dog and believe in taking all measures to prolong her life — they ask for CPR to be performed, you disagree with their decision, but despite a detailed explanation of your reasons, the owners remain unconvinced. The dog gets progressively worse over the day and experiences CPA. Do you:	Provide full CPR according to the owners’ wishes Provide one round (3 minutes) of intensive CPR and stop if no immediate response Run a “slow code” so that you can say you tried Provide no CPR as it is futile and not in the dog’s best interests

Statistical analysis

Respondents identifying as specialists were asked to indicate the specialty to which they belonged. For the purpose of statistical analysis, respondents belonging to Internal Medicine, Cardiology, Neurology, or Oncology were combined into one Internal Medicine category. Respondents belonging to Surgery or those who chose “other, or if more than one” were combined to permit statistical analysis. Respondents from corresponding American and European veterinary specialty colleges were also combined into 1 group for this purpose, e.g., the American College of Veterinary Anesthesia and the European College of Veterinary Anesthesia and Analgesia. Finally, those respondents reporting that a student, social worker/counselor, or other team member was responsible for discussion of CPR codes were combined into 1 group.

Survey data including number of participants in each category and response for each clinical scenario were imported into a statistical analysis program (SAS version 9.3; SAS Institute, Cary, North Carolina, USA). Data are presented as counts and percentages (proportions). Differences in proportions of responses to each clinical scenario among groups were calculated using either Pearson’s χ² test or Fisher’s exact test. Statistical significance was defined as P < 0.05.

Results

Sample characteristics

The survey generated a total of 733 responses. Eighty-five surveys were excluded from statistical analysis, as they were incomplete, leaving 648 respondents (Table I). Those analyzed versus those not analyzed were not significantly different by gender (P = 0.62) but were significantly more likely to be veterinarians (76%) compared to those who did not complete the survey (46% veterinarians), P < 0.0001.

Table 1.

Sample characteristics.

	Percentage
Gender (n = 641)
Female	73
Male	27
Profession (n = 648)
Veterinarian	76
Veterinary technician	9
Veterinary student	15
Student year (n = 96)
First	2
Second	43
Third	16
Fourth	40
Technician years in practice (n = 58)
< 5	16
5 to 10	24
> 10	60
Veterinarian years in practice (n = 494)
< 5	22
5 to 10	31
> 10	47
Technician — certified VTS (n = 58)
Anesthesia	9
ECC	17
No	71
Other	3
Veterinarian type of practice (n = 494)
Specialty	98
General	2
Veterinarian specialty (n = 445)
ECC	33
Anesthesia	17
Internal medicine	41
Other or > 1	8
Veterinarian location (n = 494)
North America	87
Other	13
Formal education in CPR (n = 648)
Yes	84
No	16
CPR events/year (n = 648)
0 to < 5	50
5 to 20	29
> 20	21
Are CPR codes assigned (n = 648)
Yes	75
No	13
I am not sure	12
Percent animals assigned code (n = 484)
< 25%	22
25% to < 50%	17
50% to < 75%	12
75% to 100%	49
Team member discussing code (n = 484)
Veterinarian	57
Veterinary technician	6
Veterinary student/social worker/counselor/other	2
More than one/depends on the case	35
Suspend DNR for surgery (n = 484)
Yes	21
No	58
I am not sure	21

CPR — cardiopulmonary resuscitation; DNR — do not resuscitate; VTS — Veterinary Technician Specialist; ECC — Emergency and Critical Care.

Of 648 respondents, 73% were female and 27% were male. Most of the respondents were veterinarians (76%), while 9% were veterinary technicians, and 15% were veterinary students. Most of the veterinarians surveyed worked in specialty practice (98%), with the most common specialties being emergency and critical care (33%) and internal medicine (41%), including the sub-specialties of internal medicine, neurology, oncology, and cardiology. Twenty-two percent of veterinarians had worked < 5 y in practice, 31% between 5 and 10 y, and 47% > 10 y. Most reported North America as their geographic location of practice (87%).

Eighty-four percent of respondents stated they had formal education in CPR. However, 50% reported that they only participate in 0 to 5 CPR events per year. Seventy-five percent of participants stated that their hospital assigns CPR codes to patients. Of these respondents, about 38% reported less than half the patients are assigned a code. Thirteen percent of respondents stated their hospital does not assign codes, and 12% said they were unsure. Fifty-seven percent of respondents reported that of the various veterinary team members (e.g., students, technicians, etc.), it is the veterinarian’s responsibility to discuss the code with the pet owner. Thirty-five percent reported that this discussion may be performed by more than 1 team member, or that the person responsible depends on the case. Twenty-one percent of respondents reported that DNR orders are routinely suspended before surgery, while 58% reported that they were not, and 21% were unsure.

DNR decision per clinical scenario by characteristics of practitioner

Scenario 1 — Dog with DNR order arrests during anesthesia induction

Among all respondents, 42% chose to perform full CPR, 22% chose to provide limited support, and 35% chose not to provide CPR. Men were significantly more likely to perform CPR than women (P = 0.01) (Table 2). Compared to veterinarians and veterinary technicians, veterinary students were significantly less likely to perform full CPR (P = 0.002). All respondents reporting participation in more than 5 CPR events per year were significantly more likely to perform CPR than those participating in less than 5 events (P = 0.03). Veterinarians working in general practice were significantly more likely than those in specialty practice to choose full CPR (P = 0.02). These results should be interpreted with caution given the small sample size of general practitioners. Those who indicated that their hospital assigns CPR codes were significantly more likely to choose CPR than those who did not (P = 0.05). Respondents who reported that their hospital suspends DNR orders for surgery were significantly more likely to perform CPR (P < 0.0001).

Table 2.

Comparison of different staff characteristics (e.g., Female/Male) with CPR responses (e.g., Full, Limited support, no CPR) in Scenario 1 — Dog with DNR order arrests during anesthesia induction.

Characteristic	Full CPR	Limited support	No CPR	P-valuea
Gender
Female (n = 470)	41%	25	34	0.01
Male (n = 171)	45%	15	40
Profession
Veterinarian (n = 494)	45%	20	35	0.002
Veterinary technician (n = 58)	45%	24	31
Veterinary student (n = 96)	25%	34	41
Student year
First (n = 2)	0%	100	0	0.21
Second (n = 41)	15%	39	46
Third (n = 15)	33%	33	33
Fourth (n = 38)	34%	26	40
Technician years in practice
< 5 (n = 9)	44%	44	11	0.32
5 to 10 (n = 14)	57%	21	21
> 10 (n = 35)	40%	20	40
Veterinarian years in practice
< 5 (n = 108)	46%	19	35	0.85
5 to 10 (n = 155)	42%	23	34
> 10 (n = 231)	47%	19	35
Technician certified VTS
Anesthesia (n = 5)	60%	40	0	0.63
ECC (n = 10)	50%	30	20
Other (n = 2)	50%	0	50
No (n = 41)	41%	22	37
Veterinarian type of practice
Specialty (n = 485)	44%	20	36	0.02
General (n = 9)	89%	11	0
Veterinarian specialty
Anesthesia (n = 77)	49%	14	37	0.77
Emergency (n = 149)	46%	22	32
Internal medicine (n = 183)	43%	18	39
Other (n = 36)	42%	22	36
Veterinarian location
North America (n = 428)	45%	21	34	0.08
Other (n = 66)	45%	11	44
Formal education in CPR
Yes (n = 546)	43%	23	34	0.56
No (n = 102)	39%	21	40
CPR events/year
0 to 5 (n = 323)	36%	25	39	0.03
5 to 10 (n = 187)	48%	20	32
> 20 (n = 138)	49%	18	33
Are CPR codes assigned
Yes (n = 484)	45%	22	33	0.05
No (n = 87)	40%	16	44
I am not sure (n = 77)	30%	30	40
Percent animals assigned code
< 25% (n = 105)	52%	16	32	0.33
25% to 50% (n = 80)	44%	25	31
50% to 75% (n = 60)	40%	32	28
75% to 100% (n = 239)	43%	22	35
Team member discussing code
Veterinarian	42%	22	36	0.4
Veterinary technician	38%	24	38
Veterinary student/social worker/counselor/other	78%	11	11
More than one/depends on the case	47%	24	29
Suspend DNR for surgery
Yes (n = 102)	69%	15	16	0.0001
No (n = 281)	35%	23	42
I am not sure (n = 101)	45%	28	27

^aGlobal P-value for the contingency table.

CPR — cardiopulmonary resuscitation; DNR — do not resuscitate; VTS — Veterinary Technician Specialist; ECC — Emergency and Critical Care.

Scenario 2 — Dog with DNR order arrests after fentanyl overdose

Among all respondents, 75% elected full CPR and 16% chose to provide naloxone and intubation without chest compressions (Table 3). Only 6% and 3% elected naloxone only or no CPR, respectively. Respondents who reported that their hospital suspends DNR orders for surgery were significantly more likely to perform CPR (P = 0.01) (Table 3).

Table 3.

Comparison of different staff characteristics (e.g., Female/Male) with CPR responses (e.g. Full CPR, Naloxone and intubation, Naloxone only, no CPR) in Scenario 2 — Dog with DNR order arrests after fentanyl overdose.

Characteristic	Full CPR	Naloxone and intubation	Naloxone only	No CPR	P-valuea
Gender
Female (n = 470)	75%	16	7	2	0.19
Male (n = 171)	77%	15	4	4
Profession
Veterinarian (n = 494)	78%	14	5	3	0.17
Veterinary technician (n = 58)	69%	19	10	2
Veterinary student (n = 96)	67%	23	7	3
Student year
First (n = 2)	50%	0	0	50	0.23
Second (n = 41)	76%	17	5	2
Third (n = 15)	73%	20	7	0
Fourth (n = 38)	55%	32	10	3
Technician years in practice
< 5 (n = 9)	56%	11	33	0	0.42
5 to 10 (n = 14)	71%	21	7	0
> 10 (n = 35)	71%	20	6	3
Veterinarian years in practice
< 5 (n = 108)	68%	18	11	3	0.07
5 to 10 (n = 155)	81%	12	4	3
> 10 (n = 231)	79%	14	4	3
Technician certified VTS
Anesthesia (n = 5)	80%	20	0	0	0.99
ECC (n = 10)	80%	10	10	0
Other (n = 2)	100%	0	0	0
No (n = 41)	63%	23	12	2
Veterinarian type of practice
Specialty (n = 485)	77%	15	5	3	0.71
General (n = 9)	100%	0	0	0
Veterinarian specialty
Anesthesia (n = 77)	77%	15	4	4	0.78
Emergency (n = 149)	74%	17	5	4
Internal medicine (n = 1 83)	79%	13	5	3
Other (n = 36)	89%	5	6	0
Veterinarian location
North America (n = 428)	77%	15	6	2	0.01
Other (n = 66)	79%	9	3	9
Formal education in CPR
Yes (n = 546)	75%	15	7	3	0.23
No (n = 102)	75%	20	2	3
CPR events/year
0 to 5 (n = 323)	72%	20	5	3	0.27
5 to 10 (n = 187)	78%	12	7	3
> 20 (n = 138)	78%	13	6	3
Are CPR codes assigned
Yes (n = 484)	74%	17	7	2	0.57
No (n = 87)	79%	14	2	5
I am not sure (n = 77)	78%	15	4	3
Percent animals assigned code
< 25% (n = 105)	75%	17	3	5	0.27
25% to 50% (n = 80)	71%	21	5	3
50% to 75% (n = 60)	72%	17	12	0
75% to 100% (n = 239)	75%	15	8	2
Team member discussing code
Veterinarian	74%	15	7	4	0.27
Veterinary technician	62%	21	17	0
Veterinary student/social worker/counselor/other	78%	22	0	0
More than one/depends on the case	75%	19	5	1
Suspend DNR for surgery
Yes (n = 102)	85%	11	3	1	0.01
No (n = 281)	70%	16	10	4
I am not sure (n = 101)	73%	23	3	1

^aGlobal P-value for the contingency table.

CPR — cardiopulmonary resuscitation; DNR — do not resuscitate; VTS — Veterinary Technician Specialist; ECC — Emergency and Critical Care.

Scenario 3 — Dog with DNR order arrests during sedation

Among all respondents, 60% elected full CPR and 21% chose to provide limited support. Eleven percent of respondents elected to administer reversal agents only, while 8% elected not to provide CPR. Men were significantly more likely to perform CPR than women (P = 0.001) (Table 4). Compared to veterinarians and veterinary technicians, veterinary students were significantly less likely to perform full CPR (P < 0.0001). Veterinarians reporting more years in practice were significantly more likely to perform CPR than those with less experience (P = 0.01), while technicians did not report such a difference. Veterinarians outside of North America were significantly more likely to choose not to perform CPR more often than those within North America (P = 0.01). Respondents who reported that their hospital suspends DNR orders for surgery were significantly more likely to perform CPR (P = 0.01).

Table 4.

Comparison of different staff characteristics (e.g., Female/Male) with CPR responses (e.g., full CPR, reversal and intubation, reversal only, no CPR) in Scenario 3 — Dog with DNR order arrests during sedation.

	Full CPR	Reversal and intubation	Reversal only	No CPR	P-valuea
Gender
Female (n = 470)	58%	23	13	6	0.001
Male (n = 171)	64%	16	6	14
Profession
Veterinarian (n = 494)	64%	20	8	8	0.001
Veterinary technician (n = 58)	55%	12	24	9
Veterinary student (n = 96)	39%	32	20	9
Student year
First (n = 2)	50%	0	50	0	0.96
Second (n = 41)	39%	32	17	12
Third (n = 15)	46.6%	26.6	20	6.6
Fourth (n = 38)	34%	37	21	8
Technician years in practice
< 5 (n = 9)	45%	22	22	11	0.68
5 to 10 (n = 14)	72%	0	21	7
> 10 (n = 35)	51%	14	26	9
Veterinarian years in practice
< 5 (n = 108)	53%	30	13	4	0.01
5 to 10 (n = 155)	66%	19	6	9
> 10 (n = 231)	68%	16	7	9
Technician certified VTS
Anesthesia (n = 5)	100%	0	0	0	0.5
ECC (n = 10)	50%	20	30	0
Other (n = 2)	50%	50	0	0
No (n = 41)	51%	10	27	12
Veterinarian type of practice
Specialty (n = 485)	64%	20	8	8	P = 0.72
General (n = 9)	89%	11	0	0
Veterinarian specialty
Anesthesia (n = 77)	71%	13	8	8	0.79
Emergency (n = 149)	63%	17	11	9
Internal medicine (n = 183)	63%	21	7	9
Other (n = 36)	72%	14	8	6
Veterinarian location
North America (n = 428)	62%	22	8	8	0.08
Other (n = 66)	77%	9	6	8
Formal education in CPR
Yes (n = 546)	61%	21	10	8	0.19
No (n = 102)	52%	22	16	10
CPR events/year
0 to 5 (n = 323)	54%	25	12	9	0.09
5 to 10 (n = 187)	67%	16	9	8
> 20 (n = 138)	61%	18	14	7
Are CPR codes assigned
Yes (n = 484)	61%	20	10	9	0.11
No (n = 87)	62%	22	9	7
I am not sure (n = 77)	47%	24	21	8
Percent animals assigned code
< 25% (n = 105)	72%	11	9	8	0.12
25% to 50% (n = 80)	64%	17	9	10
50% to 75% (n = 60)	47%	28	15	10
75% to 100% (n = 239)	59%	23	10	8
Team member discussing code
Veterinarian	63%	19	9	9	0.15
Veterinary technician	45%	35	10	10
Veterinary student/social worker/counselor/other	100%	0	0	0
More than one/depends on the case	59%	21	13	7
Suspend DNR for surgery
Yes (n = 102)	76%	16	6	2	0.01
No (n = 281)	55%	22	12	11
I am not sure (n = 101)	64%	19	9	8

^aGlobal P-value for the contingency table.

VTS — Veterinary Technician Specialist.

Scenario 4 — Dog with DNR order arrests after digoxin overdose

Among all respondents, the majority (63%) did not choose to perform CPR. There were no significant differences in responses to this clinical scenario among any of the groups (Table 5).

Table 5.

Comparison of different staff characteristics (e.g., Female/Male) with CPR response (would they provide CPR) in Scenario 4 — Dog with DNR order arrests after digoxin overdose.

	CPR	P-valuea
Gender
Female (n = 470)	37%	0.93
Male (n = 171)	37%
Profession
Veterinarian (n = 494)	37%	0.7
Veterinary technician (n = 58)	33%
Veterinary student (n = 96)	40%
Student year
First (n = 2)	100%	0.43
Second (n = 41)	39%
Third (n = 15)	33%
Fourth (n = 38)	39%
Technician years in practice
< 5 (n = 9)	44%	0.68
5 to 10 (n = 14)	36%
> 10 (n = 35)	29%
Veterinarian years in practice
< 5 (n = 108)	38%	0.32
5 to 10 (n = 155)	41%
> 10 (n = 231)	34%
Technician certified VTS
Anesthesia (n = 5)	20%	0.64
ECC (n = 10)	20%
Other (n = 2)	50%
No (n = 41)	37%
Veterinarian type of practice
Specialty (n = 485)	37%	0.73
General (n = 9)	44%
Veterinarian specialty
Anesthesia (n = 77)	38%	0.91
Emergency (n = 149)	35%
Internal medicine (n = 183)	39%
Other (n = 36)	36%
Veterinarian location
North America (n = 428)	37%	0.88
Other (n = 66)	38%
Formal education in CPR
Yes (n = 546)	36%	0.47
No (n = 102)	40%
CPR events/year
0 to 5 (n = 323)	40%	0.28
5 to 10 (n = 187)	33%
> 20 (n = 138)	36%
Are CPR codes assigned
Yes (n = 484)	37%	0.47
No (n = 87)	43%
I am not sure (n = 77)	34%
Percent animals assigned code
< 25% (n = 105)	39%	0.65
25% to 50% (n = 80)	41%
50% to 75% (n = 60)	33%
75% to 100% (n = 239)	35%
Team member discussing code
Veterinarian	40%	0.35
Veterinary technician	38%
Veterinary student/social worker/counselor/other	22%
More than one/depends on the case	32%
Suspend DNR for surgery
Yes (n = 102)	38%	0.27
No (n = 281)	34%
I am not sure (n = 101)	43%

^aGlobal P-value for the contingency table.

CPR — cardiopulmonary resuscitation; DNR — do not resuscitate; VTS — Veterinary Technician Specialist; ECC — Emergency and Critical Care.

Scenario 5 — Dog with metastatic neoplasia arrests, owners request CPR

Among all respondents, 63% elected to provide full CPR, 26% chose to provide 1 round of CPR and stop if there was no immediate response, 9% chose to run a “slow code,” and 2% elected not to perform CPR. Men were less likely to provide full CPR than were women (P < 0.0001) (Table 6). Students were more likely than veterinarians and veterinary technicians to choose full CPR (P = 0.04). All respondents reporting participation in more than 5 CPR events per year were significantly less likely to provide CPR than those participating in less than 5 (P < 0.0001). Veterinarian respondents within North America were significantly more likely to provide CPR, compared to those outside of North America (P < 0.0001). Most respondents (Anesthesia: 60%, Emergency and Critical Care: 58%, Internal Medicine: 62%, Other: 67%) from all specialties would choose to perform full CPR. However, emergency and critical care specialists were significantly more likely to run a “slow code” (P = 0.008). Respondents who reported a code assignment rate of 75% to 100% were more likely to provide full CPR than those reporting rates less than 75% (P = 0.001).

Table 6.

Comparison of different staff characteristics (e.g., Female/Male) with CPR responses (e.g., Full CPR, One round only, Slow code, No CPR) in Scenario 5 — Dog with metastatic neoplasia arrests, owners request CPR.

	Full CPR	One round only	Slow code	No CPR	P-valuea
Gender
Female (n = 470)	64%	27	8	1	0.0001
Male (n = 171)	59%	22	12	7
Profession
Veterinarian (n = 494)	61%	25	11	3	0.04
Veterinary technician (n = 58)	64%	26	8	2
Veterinary student (n = 96)	71%	28	1	0
Student year
First (n = 2)	100%	0	0	0	0.65
Second (n = 41)	76%	24	0	0
Third (n = 15)	60%	40	0	0
Fourth (n = 38)	68%	29	3	0
Technician years in practice
< 5 (n = 9)	56%	44	0	0	0.43
5 to 10 (n = 14)	64%	14	22	0
> 10 (n = 35)	66%	26	5	3
Veterinarian years in practice
< 5 (n = 108)	68%	25	7	0	0.24
5 to 10 (n = 155)	58%	25	14	3
> 10 (n = 231)	60%	26	10	4
Technician certified VTS
Anesthesia (n = 5)	60%	40	0	0	0.26
ECC (n = 10)	30%	50	20	0
Other (n = 2)	100%	0	0	0
No (n = 41)	71%	20	7	2
Veterinarian type of practice
Specialty (n = 485)	61%	25	11	3	0.45
General (n = 9)	44%	44	12	0
Veterinarian specialty
Anesthesia (n = 77)	60%	31	6	3	0.008
Emergency (n = 149)	58%	20	21	1
Internal medicine (n = 183)	62%	26	8	4
Other (n = 36)	67%	22	5	6
Veterinarian location
North America (n = 428)	64%	24	10	2	0.0001
Other (n = 66)	44%	32	4	10
Formal education in CPR
Yes (n = 546)	61%	27	10	2	0.37
No (n = 102)	71%	20	7	2
CPR events/year
0 to 5 (n = 323)	69%	26	4	1	0.0001
5 to 10 (n = 187)	54%	29	13	4
> 20 (n = 138)	62%	20	17	1
Are CPR codes assigned
Yes (n = 484)	63%	23	11	3	0.27
No (n = 87)	61%	31	7	1
I am not sure (n = 77)	64%	31	4	1
Percent animals assigned code
< 25% (n = 105)	55%	28	11	6	0.002
25% to 50% (n = 80)	53%	31	12	4
50% to 75% (n = 60)	55%	37	8	0
75% to 100% (n = 239)	72%	16	10	2
Team member discussing code
Veterinarian	59%	27	10	4	0.09
Veterinary technician	79%	17	4	0
Veterinary student/social worker/counselor/other	45%	22	33	0
More than one/depends on the case	68%	19	11	2
Suspend DNR for surgery
Yes (n = 102)	54%	29	13	4	0.16
No (n = 281)	68%	22	8	2
I am not sure (n = 101)	58%	24	15	3

^aGlobal P-value for the contingency table.

CPR — cardiopulmonary resuscitation; DNR — do not resuscitate; VTS — Veterinary Technician Specialist; ECC — Emergency and Critical Care.

In all scenarios, there were no significant differences in responses to the clinical scenarios among veterinary students of different years, or technicians with various years in practice or levels of certification. No significant differences were found among respondents with varied education in CPR. The team member discussing the code did not significantly affect responses to any of the clinical scenarios.

Discussion

In this study, we evaluated the use of CPR codes and adherence to DNR orders in small animal veterinary medicine. To our knowledge, this is the first international survey of veterinary practitioners investigating their clinical decisions related to patients with DNR orders experiencing CPA.

The assignment of CPR codes is variable across hospitals. Most respondents indicated that their hospital assigns codes, though some participants were unsure of the system at their practice. It is possible that in these circumstances there is no requirement, or the policy is not addressed directly with employees. Even among those who reported a policy requiring patients to have a code, only 50% indicated that a code is always assigned. Perceived lack of time to discuss CPR status or attempts to avoid this potentially difficult topic may be causes for this discrepancy.

Most participants reported that it is the responsibility of the veterinarian to discuss the code status with an owner. These results are similar to a previous study, which found that the majority of respondents felt that veterinarians should be part of the discussion, with fewer desiring technicians and students to be involved (6).

Anesthesia holds additional risks for CPA, and therefore many human hospitals require reconsideration of CPR codes before surgery. Although these risks are also present in veterinary patients, only 21% of respondents indicated that they automatically suspend DNR orders before a surgical procedure requiring anesthesia. Based on specific comments in the survey, it appears that many practitioners do not automatically suspend a DNR code. However, many discuss with the owner beforehand the possible complications associated with anesthesia in relation to a patient’s CPR code. Suspending DNR orders before surgery suggests a perception that DNR orders should not be universally applied in all circumstances. This concept could be extrapolated to iatrogenic arrests and those associated with sedation, as described in the other scenarios.

Responses to the clinical scenarios varied with some participant demographics. Men chose to perform CPR more often than women, even in cases in which this overrode an owner’s wishes. Veterinary students were less likely to choose CPR for patients with an existing DNR code. Given that students often have less clinical experience than technicians and veterinarians, it is possible that they are less comfortable with performing CPR. This correlates with the finding that less experienced veterinarians were also less likely to select the CPR option in the clinical scenarios provided. In the first 4 cases presented, choosing to provide full CPR meant overriding the wishes of the owner. With limited experience, students and less experienced veterinarians may not feel as comfortable as technicians and doctors making a judgment call that may contradict an owner’s decision. In the opposite scenario, students were more likely to act in accordance with the owner’s wishes and provide full measures for a patient they did not believe would receive any benefit from CPR. Fear of conflict with an owner could explain students’ choices in these clinical situations. It is also possible that students have had less time to form their own opinions on CPR, its effectiveness, and their own success rate, which may all play a role in willingness to perform resuscitation efforts on a terminally ill patient with a short life expectancy.

Those participants who reported involvement in more than 5 CPR cases per year chose to provide CPR to patients with existing DNR orders more often than respondents reporting participation in fewer events. Reasonably, the more experience one has with CPR, the more comfortable one becomes performing it. However, these respondents are likely more familiar firsthand with the low success rate of CPR in veterinary patients. Therefore, it is not surprising that participants with more experience were also less likely to perform CPR in a terminally ill patient.

Respondents working where codes are assigned were, overall, more likely to choose to perform CPR. Perhaps hospitals that require codes are places in which CPA is more common. If so, these respondents would be more familiar with performing CPR, which would support the hypothesis that the more experienced, the more likely one is to choose this option. It is unclear why a technician’s years in practice did not correlate with likelihood to perform CPR. It is possible that a low sample size may have skewed these results. Furthermore, among the technicians who responded, a greater percentage reported fewer years in practice. Therefore, results may have been more representative of a population of technicians with less experience.

Veterinarians practicing in North America were more likely to choose to provide CPR in the case in which owners request resuscitation against the veterinarian’s advice. Similarly, veterinarians outside of North America were more likely to not perform CPR for a dog that arrests under sedation. This could reflect a difference in the way students are taught about CPR in various geographic regions. However, these results should be interpreted with caution given that the sample size of those within North America (87% of respondents) far outweighs that of those outside.

Significant differences in willingness to perform full CPR versus not were found most often in the scenarios involving the dog under anesthesia and the dog under sedation. In the case of the dog under anesthesia, over 60% of respondents elected to provide intervention despite a DNR order. Although there is an inherently higher risk of experiencing CPA in the peri-anesthetic period, a previous study showed dogs that were anesthetized at the time of CPA were more likely to have return of spontaneous circulation and survive until discharge than those not anesthetized when CPA occurred. Similarly, in humans, CPR has a higher rate of success in these cases, as changes in cardiovascular status are noted earlier, and generally personnel and necessary supplies are closer at hand. It is reasonable that, given the higher likelihood of reviving the patient, respondents were more inclined to override the DNR in this case. One may also consider what defines a DNR order when deciding whether it is appropriate to override it. For example, if the belief is that DNR orders should only apply to arrests due to a patient’s underlying condition, then a perianesthetic arrest may not qualify.

In the case of the patient under sedation, the dog is in relatively good health compared to those in the other scenarios, as well as those patients generally at risk of CPA. It is possible that the clinical status of the animal may play a role in the choice to perform CPR. Another important consideration is the owner’s reasoning behind choosing a DNR order. In this case, the owners chose DNR based on the initial severity of the patient’s wounds. However, at the time of arrest, the patient’s status had improved significantly. One may consider if asked again, if the owners would now choose CPR, given his improved condition. Many respondents commented that DNR status should be reassessed with the owner as the patient’s status changes. Most respondents in this case, as well as with the dog that received the fentanyl overdose, chose to provide full CPR despite a DNR order. These scenarios may also be considered by some respondents to fall under the category of arrests not related to a patient’s underlying disease.

There are limitations to this study. First, although we know the total number of respondents, we do not know the response rate. Our survey was also limited largely to specialty practice, so our results may not be representative of all veterinarians. Specialty practitioners, especially those in emergency and critical care, likely deal with CPR more often than those in general practice. Although we found significant differences when evaluating veterinarians’ years in practice and experience participating in CPR, these may not have been present if we had a more even distribution between specialists and generalists. As stated before, our student and veterinary technician sample sizes were small, and therefore results may not be representative of these populations. This is also the case with veterinarians practicing outside of North America. Also, there may be a concern for multiple hypothesis testing given the number of scenarios examined in this study. Statistically significant results with P-values close to the 0.05 level should thus be interpreted with caution. Last, we did not systematically require qualitative responses to each scenario. Therefore, we are forced to speculate what aspects of the scenarios led respondents to choose the options they did.

In conclusion, there is inconsistency among practitioners not only in the use of CPR codes but also in the adherence to DNR orders. Based on these findings, it may be prudent for hospitals to establish protocols for addressing arrests not directly caused by a patient’s underlying disease as well as re-evaluating code status as a patient’s condition changes. Further research aimed at investigating owners’ general perception of CPR success and reasoning behind choosing DNR orders would be helpful for the development of more consistent policies on assignment and reconsideration of code status. CVJ